/* * QEMU System Emulator block driver * * Copyright (c) 2003 Fabrice Bellard * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "qemu/osdep.h" #include "block/trace.h" #include "block/block_int.h" #include "block/blockjob.h" #include "block/fuse.h" #include "block/nbd.h" #include "block/qdict.h" #include "qemu/error-report.h" #include "block/module_block.h" #include "qemu/main-loop.h" #include "qemu/module.h" #include "qapi/error.h" #include "qapi/qmp/qdict.h" #include "qapi/qmp/qjson.h" #include "qapi/qmp/qnull.h" #include "qapi/qmp/qstring.h" #include "qapi/qobject-output-visitor.h" #include "qapi/qapi-visit-block-core.h" #include "sysemu/block-backend.h" #include "sysemu/sysemu.h" #include "qemu/notify.h" #include "qemu/option.h" #include "qemu/coroutine.h" #include "block/qapi.h" #include "qemu/timer.h" #include "qemu/cutils.h" #include "qemu/id.h" #include "qemu/transactions.h" #include "block/coroutines.h" #ifdef CONFIG_BSD #include #include #ifndef __DragonFly__ #include #endif #endif #ifdef _WIN32 #include #endif #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */ static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states = QTAILQ_HEAD_INITIALIZER(graph_bdrv_states); static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states = QTAILQ_HEAD_INITIALIZER(all_bdrv_states); static QLIST_HEAD(, BlockDriver) bdrv_drivers = QLIST_HEAD_INITIALIZER(bdrv_drivers); static BlockDriverState *bdrv_open_inherit(const char *filename, const char *reference, QDict *options, int flags, BlockDriverState *parent, const BdrvChildClass *child_class, BdrvChildRole child_role, Error **errp); static void bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs); static int bdrv_attach_child_noperm(BlockDriverState *parent_bs, BlockDriverState *child_bs, const char *child_name, const BdrvChildClass *child_class, BdrvChildRole child_role, BdrvChild **child, Transaction *tran, Error **errp); static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, Error **errp); static void bdrv_reopen_commit(BDRVReopenState *reopen_state); static void bdrv_reopen_abort(BDRVReopenState *reopen_state); /* If non-zero, use only whitelisted block drivers */ static int use_bdrv_whitelist; #ifdef _WIN32 static int is_windows_drive_prefix(const char *filename) { return (((filename[0] >= 'a' && filename[0] <= 'z') || (filename[0] >= 'A' && filename[0] <= 'Z')) && filename[1] == ':'); } int is_windows_drive(const char *filename) { if (is_windows_drive_prefix(filename) && filename[2] == '\0') return 1; if (strstart(filename, "\\\\.\\", NULL) || strstart(filename, "//./", NULL)) return 1; return 0; } #endif size_t bdrv_opt_mem_align(BlockDriverState *bs) { if (!bs || !bs->drv) { /* page size or 4k (hdd sector size) should be on the safe side */ return MAX(4096, qemu_real_host_page_size); } return bs->bl.opt_mem_alignment; } size_t bdrv_min_mem_align(BlockDriverState *bs) { if (!bs || !bs->drv) { /* page size or 4k (hdd sector size) should be on the safe side */ return MAX(4096, qemu_real_host_page_size); } return bs->bl.min_mem_alignment; } /* check if the path starts with ":" */ int path_has_protocol(const char *path) { const char *p; #ifdef _WIN32 if (is_windows_drive(path) || is_windows_drive_prefix(path)) { return 0; } p = path + strcspn(path, ":/\\"); #else p = path + strcspn(path, ":/"); #endif return *p == ':'; } int path_is_absolute(const char *path) { #ifdef _WIN32 /* specific case for names like: "\\.\d:" */ if (is_windows_drive(path) || is_windows_drive_prefix(path)) { return 1; } return (*path == '/' || *path == '\\'); #else return (*path == '/'); #endif } /* if filename is absolute, just return its duplicate. Otherwise, build a path to it by considering it is relative to base_path. URL are supported. */ char *path_combine(const char *base_path, const char *filename) { const char *protocol_stripped = NULL; const char *p, *p1; char *result; int len; if (path_is_absolute(filename)) { return g_strdup(filename); } if (path_has_protocol(base_path)) { protocol_stripped = strchr(base_path, ':'); if (protocol_stripped) { protocol_stripped++; } } p = protocol_stripped ?: base_path; p1 = strrchr(base_path, '/'); #ifdef _WIN32 { const char *p2; p2 = strrchr(base_path, '\\'); if (!p1 || p2 > p1) { p1 = p2; } } #endif if (p1) { p1++; } else { p1 = base_path; } if (p1 > p) { p = p1; } len = p - base_path; result = g_malloc(len + strlen(filename) + 1); memcpy(result, base_path, len); strcpy(result + len, filename); return result; } /* * Helper function for bdrv_parse_filename() implementations to remove optional * protocol prefixes (especially "file:") from a filename and for putting the * stripped filename into the options QDict if there is such a prefix. */ void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix, QDict *options) { if (strstart(filename, prefix, &filename)) { /* Stripping the explicit protocol prefix may result in a protocol * prefix being (wrongly) detected (if the filename contains a colon) */ if (path_has_protocol(filename)) { GString *fat_filename; /* This means there is some colon before the first slash; therefore, * this cannot be an absolute path */ assert(!path_is_absolute(filename)); /* And we can thus fix the protocol detection issue by prefixing it * by "./" */ fat_filename = g_string_new("./"); g_string_append(fat_filename, filename); assert(!path_has_protocol(fat_filename->str)); qdict_put(options, "filename", qstring_from_gstring(fat_filename)); } else { /* If no protocol prefix was detected, we can use the shortened * filename as-is */ qdict_put_str(options, "filename", filename); } } } /* Returns whether the image file is opened as read-only. Note that this can * return false and writing to the image file is still not possible because the * image is inactivated. */ bool bdrv_is_read_only(BlockDriverState *bs) { return bs->read_only; } int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, bool ignore_allow_rdw, Error **errp) { /* Do not set read_only if copy_on_read is enabled */ if (bs->copy_on_read && read_only) { error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled", bdrv_get_device_or_node_name(bs)); return -EINVAL; } /* Do not clear read_only if it is prohibited */ if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) && !ignore_allow_rdw) { error_setg(errp, "Node '%s' is read only", bdrv_get_device_or_node_name(bs)); return -EPERM; } return 0; } /* * Called by a driver that can only provide a read-only image. * * Returns 0 if the node is already read-only or it could switch the node to * read-only because BDRV_O_AUTO_RDONLY is set. * * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg * is not NULL, it is used as the error message for the Error object. */ int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg, Error **errp) { int ret = 0; if (!(bs->open_flags & BDRV_O_RDWR)) { return 0; } if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) { goto fail; } ret = bdrv_can_set_read_only(bs, true, false, NULL); if (ret < 0) { goto fail; } bs->read_only = true; bs->open_flags &= ~BDRV_O_RDWR; return 0; fail: error_setg(errp, "%s", errmsg ?: "Image is read-only"); return -EACCES; } /* * If @backing is empty, this function returns NULL without setting * @errp. In all other cases, NULL will only be returned with @errp * set. * * Therefore, a return value of NULL without @errp set means that * there is no backing file; if @errp is set, there is one but its * absolute filename cannot be generated. */ char *bdrv_get_full_backing_filename_from_filename(const char *backed, const char *backing, Error **errp) { if (backing[0] == '\0') { return NULL; } else if (path_has_protocol(backing) || path_is_absolute(backing)) { return g_strdup(backing); } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) { error_setg(errp, "Cannot use relative backing file names for '%s'", backed); return NULL; } else { return path_combine(backed, backing); } } /* * If @filename is empty or NULL, this function returns NULL without * setting @errp. In all other cases, NULL will only be returned with * @errp set. */ static char *bdrv_make_absolute_filename(BlockDriverState *relative_to, const char *filename, Error **errp) { char *dir, *full_name; if (!filename || filename[0] == '\0') { return NULL; } else if (path_has_protocol(filename) || path_is_absolute(filename)) { return g_strdup(filename); } dir = bdrv_dirname(relative_to, errp); if (!dir) { return NULL; } full_name = g_strconcat(dir, filename, NULL); g_free(dir); return full_name; } char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp) { return bdrv_make_absolute_filename(bs, bs->backing_file, errp); } void bdrv_register(BlockDriver *bdrv) { assert(bdrv->format_name); QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list); } BlockDriverState *bdrv_new(void) { BlockDriverState *bs; int i; bs = g_new0(BlockDriverState, 1); QLIST_INIT(&bs->dirty_bitmaps); for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { QLIST_INIT(&bs->op_blockers[i]); } notifier_with_return_list_init(&bs->before_write_notifiers); qemu_co_mutex_init(&bs->reqs_lock); qemu_mutex_init(&bs->dirty_bitmap_mutex); bs->refcnt = 1; bs->aio_context = qemu_get_aio_context(); qemu_co_queue_init(&bs->flush_queue); for (i = 0; i < bdrv_drain_all_count; i++) { bdrv_drained_begin(bs); } QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list); return bs; } static BlockDriver *bdrv_do_find_format(const char *format_name) { BlockDriver *drv1; QLIST_FOREACH(drv1, &bdrv_drivers, list) { if (!strcmp(drv1->format_name, format_name)) { return drv1; } } return NULL; } BlockDriver *bdrv_find_format(const char *format_name) { BlockDriver *drv1; int i; drv1 = bdrv_do_find_format(format_name); if (drv1) { return drv1; } /* The driver isn't registered, maybe we need to load a module */ for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { if (!strcmp(block_driver_modules[i].format_name, format_name)) { block_module_load_one(block_driver_modules[i].library_name); break; } } return bdrv_do_find_format(format_name); } static int bdrv_format_is_whitelisted(const char *format_name, bool read_only) { static const char *whitelist_rw[] = { CONFIG_BDRV_RW_WHITELIST NULL }; static const char *whitelist_ro[] = { CONFIG_BDRV_RO_WHITELIST NULL }; const char **p; if (!whitelist_rw[0] && !whitelist_ro[0]) { return 1; /* no whitelist, anything goes */ } for (p = whitelist_rw; *p; p++) { if (!strcmp(format_name, *p)) { return 1; } } if (read_only) { for (p = whitelist_ro; *p; p++) { if (!strcmp(format_name, *p)) { return 1; } } } return 0; } int bdrv_is_whitelisted(BlockDriver *drv, bool read_only) { return bdrv_format_is_whitelisted(drv->format_name, read_only); } bool bdrv_uses_whitelist(void) { return use_bdrv_whitelist; } typedef struct CreateCo { BlockDriver *drv; char *filename; QemuOpts *opts; int ret; Error *err; } CreateCo; static void coroutine_fn bdrv_create_co_entry(void *opaque) { Error *local_err = NULL; int ret; CreateCo *cco = opaque; assert(cco->drv); ret = cco->drv->bdrv_co_create_opts(cco->drv, cco->filename, cco->opts, &local_err); error_propagate(&cco->err, local_err); cco->ret = ret; } int bdrv_create(BlockDriver *drv, const char* filename, QemuOpts *opts, Error **errp) { int ret; Coroutine *co; CreateCo cco = { .drv = drv, .filename = g_strdup(filename), .opts = opts, .ret = NOT_DONE, .err = NULL, }; if (!drv->bdrv_co_create_opts) { error_setg(errp, "Driver '%s' does not support image creation", drv->format_name); ret = -ENOTSUP; goto out; } if (qemu_in_coroutine()) { /* Fast-path if already in coroutine context */ bdrv_create_co_entry(&cco); } else { co = qemu_coroutine_create(bdrv_create_co_entry, &cco); qemu_coroutine_enter(co); while (cco.ret == NOT_DONE) { aio_poll(qemu_get_aio_context(), true); } } ret = cco.ret; if (ret < 0) { if (cco.err) { error_propagate(errp, cco.err); } else { error_setg_errno(errp, -ret, "Could not create image"); } } out: g_free(cco.filename); return ret; } /** * Helper function for bdrv_create_file_fallback(): Resize @blk to at * least the given @minimum_size. * * On success, return @blk's actual length. * Otherwise, return -errno. */ static int64_t create_file_fallback_truncate(BlockBackend *blk, int64_t minimum_size, Error **errp) { Error *local_err = NULL; int64_t size; int ret; ret = blk_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0, &local_err); if (ret < 0 && ret != -ENOTSUP) { error_propagate(errp, local_err); return ret; } size = blk_getlength(blk); if (size < 0) { error_free(local_err); error_setg_errno(errp, -size, "Failed to inquire the new image file's length"); return size; } if (size < minimum_size) { /* Need to grow the image, but we failed to do that */ error_propagate(errp, local_err); return -ENOTSUP; } error_free(local_err); local_err = NULL; return size; } /** * Helper function for bdrv_create_file_fallback(): Zero the first * sector to remove any potentially pre-existing image header. */ static int create_file_fallback_zero_first_sector(BlockBackend *blk, int64_t current_size, Error **errp) { int64_t bytes_to_clear; int ret; bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE); if (bytes_to_clear) { ret = blk_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP); if (ret < 0) { error_setg_errno(errp, -ret, "Failed to clear the new image's first sector"); return ret; } } return 0; } /** * Simple implementation of bdrv_co_create_opts for protocol drivers * which only support creation via opening a file * (usually existing raw storage device) */ int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv, const char *filename, QemuOpts *opts, Error **errp) { BlockBackend *blk; QDict *options; int64_t size = 0; char *buf = NULL; PreallocMode prealloc; Error *local_err = NULL; int ret; size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0); buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC); prealloc = qapi_enum_parse(&PreallocMode_lookup, buf, PREALLOC_MODE_OFF, &local_err); g_free(buf); if (local_err) { error_propagate(errp, local_err); return -EINVAL; } if (prealloc != PREALLOC_MODE_OFF) { error_setg(errp, "Unsupported preallocation mode '%s'", PreallocMode_str(prealloc)); return -ENOTSUP; } options = qdict_new(); qdict_put_str(options, "driver", drv->format_name); blk = blk_new_open(filename, NULL, options, BDRV_O_RDWR | BDRV_O_RESIZE, errp); if (!blk) { error_prepend(errp, "Protocol driver '%s' does not support image " "creation, and opening the image failed: ", drv->format_name); return -EINVAL; } size = create_file_fallback_truncate(blk, size, errp); if (size < 0) { ret = size; goto out; } ret = create_file_fallback_zero_first_sector(blk, size, errp); if (ret < 0) { goto out; } ret = 0; out: blk_unref(blk); return ret; } int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp) { QemuOpts *protocol_opts; BlockDriver *drv; QDict *qdict; int ret; drv = bdrv_find_protocol(filename, true, errp); if (drv == NULL) { return -ENOENT; } if (!drv->create_opts) { error_setg(errp, "Driver '%s' does not support image creation", drv->format_name); return -ENOTSUP; } /* * 'opts' contains a QemuOptsList with a combination of format and protocol * default values. * * The format properly removes its options, but the default values remain * in 'opts->list'. So if the protocol has options with the same name * (e.g. rbd has 'cluster_size' as qcow2), it will see the default values * of the format, since for overlapping options, the format wins. * * To avoid this issue, lets convert QemuOpts to QDict, in this way we take * only the set options, and then convert it back to QemuOpts, using the * create_opts of the protocol. So the new QemuOpts, will contain only the * protocol defaults. */ qdict = qemu_opts_to_qdict(opts, NULL); protocol_opts = qemu_opts_from_qdict(drv->create_opts, qdict, errp); if (protocol_opts == NULL) { ret = -EINVAL; goto out; } ret = bdrv_create(drv, filename, protocol_opts, errp); out: qemu_opts_del(protocol_opts); qobject_unref(qdict); return ret; } int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp) { Error *local_err = NULL; int ret; assert(bs != NULL); if (!bs->drv) { error_setg(errp, "Block node '%s' is not opened", bs->filename); return -ENOMEDIUM; } if (!bs->drv->bdrv_co_delete_file) { error_setg(errp, "Driver '%s' does not support image deletion", bs->drv->format_name); return -ENOTSUP; } ret = bs->drv->bdrv_co_delete_file(bs, &local_err); if (ret < 0) { error_propagate(errp, local_err); } return ret; } void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs) { Error *local_err = NULL; int ret; if (!bs) { return; } ret = bdrv_co_delete_file(bs, &local_err); /* * ENOTSUP will happen if the block driver doesn't support * the 'bdrv_co_delete_file' interface. This is a predictable * scenario and shouldn't be reported back to the user. */ if (ret == -ENOTSUP) { error_free(local_err); } else if (ret < 0) { error_report_err(local_err); } } /** * Try to get @bs's logical and physical block size. * On success, store them in @bsz struct and return 0. * On failure return -errno. * @bs must not be empty. */ int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz) { BlockDriver *drv = bs->drv; BlockDriverState *filtered = bdrv_filter_bs(bs); if (drv && drv->bdrv_probe_blocksizes) { return drv->bdrv_probe_blocksizes(bs, bsz); } else if (filtered) { return bdrv_probe_blocksizes(filtered, bsz); } return -ENOTSUP; } /** * Try to get @bs's geometry (cyls, heads, sectors). * On success, store them in @geo struct and return 0. * On failure return -errno. * @bs must not be empty. */ int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo) { BlockDriver *drv = bs->drv; BlockDriverState *filtered = bdrv_filter_bs(bs); if (drv && drv->bdrv_probe_geometry) { return drv->bdrv_probe_geometry(bs, geo); } else if (filtered) { return bdrv_probe_geometry(filtered, geo); } return -ENOTSUP; } /* * Create a uniquely-named empty temporary file. * Return 0 upon success, otherwise a negative errno value. */ int get_tmp_filename(char *filename, int size) { #ifdef _WIN32 char temp_dir[MAX_PATH]; /* GetTempFileName requires that its output buffer (4th param) have length MAX_PATH or greater. */ assert(size >= MAX_PATH); return (GetTempPath(MAX_PATH, temp_dir) && GetTempFileName(temp_dir, "qem", 0, filename) ? 0 : -GetLastError()); #else int fd; const char *tmpdir; tmpdir = getenv("TMPDIR"); if (!tmpdir) { tmpdir = "/var/tmp"; } if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) { return -EOVERFLOW; } fd = mkstemp(filename); if (fd < 0) { return -errno; } if (close(fd) != 0) { unlink(filename); return -errno; } return 0; #endif } /* * Detect host devices. By convention, /dev/cdrom[N] is always * recognized as a host CDROM. */ static BlockDriver *find_hdev_driver(const char *filename) { int score_max = 0, score; BlockDriver *drv = NULL, *d; QLIST_FOREACH(d, &bdrv_drivers, list) { if (d->bdrv_probe_device) { score = d->bdrv_probe_device(filename); if (score > score_max) { score_max = score; drv = d; } } } return drv; } static BlockDriver *bdrv_do_find_protocol(const char *protocol) { BlockDriver *drv1; QLIST_FOREACH(drv1, &bdrv_drivers, list) { if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) { return drv1; } } return NULL; } BlockDriver *bdrv_find_protocol(const char *filename, bool allow_protocol_prefix, Error **errp) { BlockDriver *drv1; char protocol[128]; int len; const char *p; int i; /* TODO Drivers without bdrv_file_open must be specified explicitly */ /* * XXX(hch): we really should not let host device detection * override an explicit protocol specification, but moving this * later breaks access to device names with colons in them. * Thanks to the brain-dead persistent naming schemes on udev- * based Linux systems those actually are quite common. */ drv1 = find_hdev_driver(filename); if (drv1) { return drv1; } if (!path_has_protocol(filename) || !allow_protocol_prefix) { return &bdrv_file; } p = strchr(filename, ':'); assert(p != NULL); len = p - filename; if (len > sizeof(protocol) - 1) len = sizeof(protocol) - 1; memcpy(protocol, filename, len); protocol[len] = '\0'; drv1 = bdrv_do_find_protocol(protocol); if (drv1) { return drv1; } for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { if (block_driver_modules[i].protocol_name && !strcmp(block_driver_modules[i].protocol_name, protocol)) { block_module_load_one(block_driver_modules[i].library_name); break; } } drv1 = bdrv_do_find_protocol(protocol); if (!drv1) { error_setg(errp, "Unknown protocol '%s'", protocol); } return drv1; } /* * Guess image format by probing its contents. * This is not a good idea when your image is raw (CVE-2008-2004), but * we do it anyway for backward compatibility. * * @buf contains the image's first @buf_size bytes. * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE, * but can be smaller if the image file is smaller) * @filename is its filename. * * For all block drivers, call the bdrv_probe() method to get its * probing score. * Return the first block driver with the highest probing score. */ BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size, const char *filename) { int score_max = 0, score; BlockDriver *drv = NULL, *d; QLIST_FOREACH(d, &bdrv_drivers, list) { if (d->bdrv_probe) { score = d->bdrv_probe(buf, buf_size, filename); if (score > score_max) { score_max = score; drv = d; } } } return drv; } static int find_image_format(BlockBackend *file, const char *filename, BlockDriver **pdrv, Error **errp) { BlockDriver *drv; uint8_t buf[BLOCK_PROBE_BUF_SIZE]; int ret = 0; /* Return the raw BlockDriver * to scsi-generic devices or empty drives */ if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) { *pdrv = &bdrv_raw; return ret; } ret = blk_pread(file, 0, buf, sizeof(buf)); if (ret < 0) { error_setg_errno(errp, -ret, "Could not read image for determining its " "format"); *pdrv = NULL; return ret; } drv = bdrv_probe_all(buf, ret, filename); if (!drv) { error_setg(errp, "Could not determine image format: No compatible " "driver found"); ret = -ENOENT; } *pdrv = drv; return ret; } /** * Set the current 'total_sectors' value * Return 0 on success, -errno on error. */ int refresh_total_sectors(BlockDriverState *bs, int64_t hint) { BlockDriver *drv = bs->drv; if (!drv) { return -ENOMEDIUM; } /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */ if (bdrv_is_sg(bs)) return 0; /* query actual device if possible, otherwise just trust the hint */ if (drv->bdrv_getlength) { int64_t length = drv->bdrv_getlength(bs); if (length < 0) { return length; } hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE); } bs->total_sectors = hint; if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) { return -EFBIG; } return 0; } /** * Combines a QDict of new block driver @options with any missing options taken * from @old_options, so that leaving out an option defaults to its old value. */ static void bdrv_join_options(BlockDriverState *bs, QDict *options, QDict *old_options) { if (bs->drv && bs->drv->bdrv_join_options) { bs->drv->bdrv_join_options(options, old_options); } else { qdict_join(options, old_options, false); } } static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts, int open_flags, Error **errp) { Error *local_err = NULL; char *value = qemu_opt_get_del(opts, "detect-zeroes"); BlockdevDetectZeroesOptions detect_zeroes = qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value, BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err); g_free(value); if (local_err) { error_propagate(errp, local_err); return detect_zeroes; } if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP && !(open_flags & BDRV_O_UNMAP)) { error_setg(errp, "setting detect-zeroes to unmap is not allowed " "without setting discard operation to unmap"); } return detect_zeroes; } /** * Set open flags for aio engine * * Return 0 on success, -1 if the engine specified is invalid */ int bdrv_parse_aio(const char *mode, int *flags) { if (!strcmp(mode, "threads")) { /* do nothing, default */ } else if (!strcmp(mode, "native")) { *flags |= BDRV_O_NATIVE_AIO; #ifdef CONFIG_LINUX_IO_URING } else if (!strcmp(mode, "io_uring")) { *flags |= BDRV_O_IO_URING; #endif } else { return -1; } return 0; } /** * Set open flags for a given discard mode * * Return 0 on success, -1 if the discard mode was invalid. */ int bdrv_parse_discard_flags(const char *mode, int *flags) { *flags &= ~BDRV_O_UNMAP; if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) { /* do nothing */ } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) { *flags |= BDRV_O_UNMAP; } else { return -1; } return 0; } /** * Set open flags for a given cache mode * * Return 0 on success, -1 if the cache mode was invalid. */ int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough) { *flags &= ~BDRV_O_CACHE_MASK; if (!strcmp(mode, "off") || !strcmp(mode, "none")) { *writethrough = false; *flags |= BDRV_O_NOCACHE; } else if (!strcmp(mode, "directsync")) { *writethrough = true; *flags |= BDRV_O_NOCACHE; } else if (!strcmp(mode, "writeback")) { *writethrough = false; } else if (!strcmp(mode, "unsafe")) { *writethrough = false; *flags |= BDRV_O_NO_FLUSH; } else if (!strcmp(mode, "writethrough")) { *writethrough = true; } else { return -1; } return 0; } static char *bdrv_child_get_parent_desc(BdrvChild *c) { BlockDriverState *parent = c->opaque; return g_strdup(bdrv_get_device_or_node_name(parent)); } static void bdrv_child_cb_drained_begin(BdrvChild *child) { BlockDriverState *bs = child->opaque; bdrv_do_drained_begin_quiesce(bs, NULL, false); } static bool bdrv_child_cb_drained_poll(BdrvChild *child) { BlockDriverState *bs = child->opaque; return bdrv_drain_poll(bs, false, NULL, false); } static void bdrv_child_cb_drained_end(BdrvChild *child, int *drained_end_counter) { BlockDriverState *bs = child->opaque; bdrv_drained_end_no_poll(bs, drained_end_counter); } static int bdrv_child_cb_inactivate(BdrvChild *child) { BlockDriverState *bs = child->opaque; assert(bs->open_flags & BDRV_O_INACTIVE); return 0; } static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx, GSList **ignore, Error **errp) { BlockDriverState *bs = child->opaque; return bdrv_can_set_aio_context(bs, ctx, ignore, errp); } static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx, GSList **ignore) { BlockDriverState *bs = child->opaque; return bdrv_set_aio_context_ignore(bs, ctx, ignore); } /* * Returns the options and flags that a temporary snapshot should get, based on * the originally requested flags (the originally requested image will have * flags like a backing file) */ static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options, int parent_flags, QDict *parent_options) { *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY; /* For temporary files, unconditional cache=unsafe is fine */ qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off"); qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on"); /* Copy the read-only and discard options from the parent */ qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD); /* aio=native doesn't work for cache.direct=off, so disable it for the * temporary snapshot */ *child_flags &= ~BDRV_O_NATIVE_AIO; } static void bdrv_backing_attach(BdrvChild *c) { BlockDriverState *parent = c->opaque; BlockDriverState *backing_hd = c->bs; assert(!parent->backing_blocker); error_setg(&parent->backing_blocker, "node is used as backing hd of '%s'", bdrv_get_device_or_node_name(parent)); bdrv_refresh_filename(backing_hd); parent->open_flags &= ~BDRV_O_NO_BACKING; bdrv_op_block_all(backing_hd, parent->backing_blocker); /* Otherwise we won't be able to commit or stream */ bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET, parent->backing_blocker); bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM, parent->backing_blocker); /* * We do backup in 3 ways: * 1. drive backup * The target bs is new opened, and the source is top BDS * 2. blockdev backup * Both the source and the target are top BDSes. * 3. internal backup(used for block replication) * Both the source and the target are backing file * * In case 1 and 2, neither the source nor the target is the backing file. * In case 3, we will block the top BDS, so there is only one block job * for the top BDS and its backing chain. */ bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE, parent->backing_blocker); bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET, parent->backing_blocker); } static void bdrv_backing_detach(BdrvChild *c) { BlockDriverState *parent = c->opaque; assert(parent->backing_blocker); bdrv_op_unblock_all(c->bs, parent->backing_blocker); error_free(parent->backing_blocker); parent->backing_blocker = NULL; } static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base, const char *filename, Error **errp) { BlockDriverState *parent = c->opaque; bool read_only = bdrv_is_read_only(parent); int ret; if (read_only) { ret = bdrv_reopen_set_read_only(parent, false, errp); if (ret < 0) { return ret; } } ret = bdrv_change_backing_file(parent, filename, base->drv ? base->drv->format_name : "", false); if (ret < 0) { error_setg_errno(errp, -ret, "Could not update backing file link"); } if (read_only) { bdrv_reopen_set_read_only(parent, true, NULL); } return ret; } /* * Returns the options and flags that a generic child of a BDS should * get, based on the given options and flags for the parent BDS. */ static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format, int *child_flags, QDict *child_options, int parent_flags, QDict *parent_options) { int flags = parent_flags; /* * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL. * Generally, the question to answer is: Should this child be * format-probed by default? */ /* * Pure and non-filtered data children of non-format nodes should * be probed by default (even when the node itself has BDRV_O_PROTOCOL * set). This only affects a very limited set of drivers (namely * quorum and blkverify when this comment was written). * Force-clear BDRV_O_PROTOCOL then. */ if (!parent_is_format && (role & BDRV_CHILD_DATA) && !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED))) { flags &= ~BDRV_O_PROTOCOL; } /* * All children of format nodes (except for COW children) and all * metadata children in general should never be format-probed. * Force-set BDRV_O_PROTOCOL then. */ if ((parent_is_format && !(role & BDRV_CHILD_COW)) || (role & BDRV_CHILD_METADATA)) { flags |= BDRV_O_PROTOCOL; } /* * If the cache mode isn't explicitly set, inherit direct and no-flush from * the parent. */ qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT); qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH); qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE); if (role & BDRV_CHILD_COW) { /* backing files are opened read-only by default */ qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on"); qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off"); } else { /* Inherit the read-only option from the parent if it's not set */ qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); qdict_copy_default(child_options, parent_options, BDRV_OPT_AUTO_READ_ONLY); } /* * bdrv_co_pdiscard() respects unmap policy for the parent, so we * can default to enable it on lower layers regardless of the * parent option. */ qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap"); /* Clear flags that only apply to the top layer */ flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ); if (role & BDRV_CHILD_METADATA) { flags &= ~BDRV_O_NO_IO; } if (role & BDRV_CHILD_COW) { flags &= ~BDRV_O_TEMPORARY; } *child_flags = flags; } static void bdrv_child_cb_attach(BdrvChild *child) { BlockDriverState *bs = child->opaque; if (child->role & BDRV_CHILD_COW) { bdrv_backing_attach(child); } bdrv_apply_subtree_drain(child, bs); } static void bdrv_child_cb_detach(BdrvChild *child) { BlockDriverState *bs = child->opaque; if (child->role & BDRV_CHILD_COW) { bdrv_backing_detach(child); } bdrv_unapply_subtree_drain(child, bs); } static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base, const char *filename, Error **errp) { if (c->role & BDRV_CHILD_COW) { return bdrv_backing_update_filename(c, base, filename, errp); } return 0; } static AioContext *bdrv_child_cb_get_parent_aio_context(BdrvChild *c) { BlockDriverState *bs = c->opaque; return bdrv_get_aio_context(bs); } const BdrvChildClass child_of_bds = { .parent_is_bds = true, .get_parent_desc = bdrv_child_get_parent_desc, .inherit_options = bdrv_inherited_options, .drained_begin = bdrv_child_cb_drained_begin, .drained_poll = bdrv_child_cb_drained_poll, .drained_end = bdrv_child_cb_drained_end, .attach = bdrv_child_cb_attach, .detach = bdrv_child_cb_detach, .inactivate = bdrv_child_cb_inactivate, .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx, .set_aio_ctx = bdrv_child_cb_set_aio_ctx, .update_filename = bdrv_child_cb_update_filename, .get_parent_aio_context = bdrv_child_cb_get_parent_aio_context, }; AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c) { return c->klass->get_parent_aio_context(c); } static int bdrv_open_flags(BlockDriverState *bs, int flags) { int open_flags = flags; /* * Clear flags that are internal to the block layer before opening the * image. */ open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL); return open_flags; } static void update_flags_from_options(int *flags, QemuOpts *opts) { *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY); if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) { *flags |= BDRV_O_NO_FLUSH; } if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) { *flags |= BDRV_O_NOCACHE; } if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) { *flags |= BDRV_O_RDWR; } if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) { *flags |= BDRV_O_AUTO_RDONLY; } } static void update_options_from_flags(QDict *options, int flags) { if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) { qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE); } if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) { qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH, flags & BDRV_O_NO_FLUSH); } if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) { qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR)); } if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) { qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY, flags & BDRV_O_AUTO_RDONLY); } } static void bdrv_assign_node_name(BlockDriverState *bs, const char *node_name, Error **errp) { char *gen_node_name = NULL; if (!node_name) { node_name = gen_node_name = id_generate(ID_BLOCK); } else if (!id_wellformed(node_name)) { /* * Check for empty string or invalid characters, but not if it is * generated (generated names use characters not available to the user) */ error_setg(errp, "Invalid node-name: '%s'", node_name); return; } /* takes care of avoiding namespaces collisions */ if (blk_by_name(node_name)) { error_setg(errp, "node-name=%s is conflicting with a device id", node_name); goto out; } /* takes care of avoiding duplicates node names */ if (bdrv_find_node(node_name)) { error_setg(errp, "Duplicate nodes with node-name='%s'", node_name); goto out; } /* Make sure that the node name isn't truncated */ if (strlen(node_name) >= sizeof(bs->node_name)) { error_setg(errp, "Node name too long"); goto out; } /* copy node name into the bs and insert it into the graph list */ pstrcpy(bs->node_name, sizeof(bs->node_name), node_name); QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list); out: g_free(gen_node_name); } static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name, QDict *options, int open_flags, Error **errp) { Error *local_err = NULL; int i, ret; bdrv_assign_node_name(bs, node_name, &local_err); if (local_err) { error_propagate(errp, local_err); return -EINVAL; } bs->drv = drv; bs->read_only = !(bs->open_flags & BDRV_O_RDWR); bs->opaque = g_malloc0(drv->instance_size); if (drv->bdrv_file_open) { assert(!drv->bdrv_needs_filename || bs->filename[0]); ret = drv->bdrv_file_open(bs, options, open_flags, &local_err); } else if (drv->bdrv_open) { ret = drv->bdrv_open(bs, options, open_flags, &local_err); } else { ret = 0; } if (ret < 0) { if (local_err) { error_propagate(errp, local_err); } else if (bs->filename[0]) { error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename); } else { error_setg_errno(errp, -ret, "Could not open image"); } goto open_failed; } ret = refresh_total_sectors(bs, bs->total_sectors); if (ret < 0) { error_setg_errno(errp, -ret, "Could not refresh total sector count"); return ret; } bdrv_refresh_limits(bs, &local_err); if (local_err) { error_propagate(errp, local_err); return -EINVAL; } assert(bdrv_opt_mem_align(bs) != 0); assert(bdrv_min_mem_align(bs) != 0); assert(is_power_of_2(bs->bl.request_alignment)); for (i = 0; i < bs->quiesce_counter; i++) { if (drv->bdrv_co_drain_begin) { drv->bdrv_co_drain_begin(bs); } } return 0; open_failed: bs->drv = NULL; if (bs->file != NULL) { bdrv_unref_child(bs, bs->file); bs->file = NULL; } g_free(bs->opaque); bs->opaque = NULL; return ret; } BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name, int flags, Error **errp) { BlockDriverState *bs; int ret; bs = bdrv_new(); bs->open_flags = flags; bs->explicit_options = qdict_new(); bs->options = qdict_new(); bs->opaque = NULL; update_options_from_flags(bs->options, flags); ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp); if (ret < 0) { qobject_unref(bs->explicit_options); bs->explicit_options = NULL; qobject_unref(bs->options); bs->options = NULL; bdrv_unref(bs); return NULL; } return bs; } QemuOptsList bdrv_runtime_opts = { .name = "bdrv_common", .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head), .desc = { { .name = "node-name", .type = QEMU_OPT_STRING, .help = "Node name of the block device node", }, { .name = "driver", .type = QEMU_OPT_STRING, .help = "Block driver to use for the node", }, { .name = BDRV_OPT_CACHE_DIRECT, .type = QEMU_OPT_BOOL, .help = "Bypass software writeback cache on the host", }, { .name = BDRV_OPT_CACHE_NO_FLUSH, .type = QEMU_OPT_BOOL, .help = "Ignore flush requests", }, { .name = BDRV_OPT_READ_ONLY, .type = QEMU_OPT_BOOL, .help = "Node is opened in read-only mode", }, { .name = BDRV_OPT_AUTO_READ_ONLY, .type = QEMU_OPT_BOOL, .help = "Node can become read-only if opening read-write fails", }, { .name = "detect-zeroes", .type = QEMU_OPT_STRING, .help = "try to optimize zero writes (off, on, unmap)", }, { .name = BDRV_OPT_DISCARD, .type = QEMU_OPT_STRING, .help = "discard operation (ignore/off, unmap/on)", }, { .name = BDRV_OPT_FORCE_SHARE, .type = QEMU_OPT_BOOL, .help = "always accept other writers (default: off)", }, { /* end of list */ } }, }; QemuOptsList bdrv_create_opts_simple = { .name = "simple-create-opts", .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head), .desc = { { .name = BLOCK_OPT_SIZE, .type = QEMU_OPT_SIZE, .help = "Virtual disk size" }, { .name = BLOCK_OPT_PREALLOC, .type = QEMU_OPT_STRING, .help = "Preallocation mode (allowed values: off)" }, { /* end of list */ } } }; /* * Common part for opening disk images and files * * Removes all processed options from *options. */ static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file, QDict *options, Error **errp) { int ret, open_flags; const char *filename; const char *driver_name = NULL; const char *node_name = NULL; const char *discard; QemuOpts *opts; BlockDriver *drv; Error *local_err = NULL; assert(bs->file == NULL); assert(options != NULL && bs->options != options); opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); if (!qemu_opts_absorb_qdict(opts, options, errp)) { ret = -EINVAL; goto fail_opts; } update_flags_from_options(&bs->open_flags, opts); driver_name = qemu_opt_get(opts, "driver"); drv = bdrv_find_format(driver_name); assert(drv != NULL); bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false); if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) { error_setg(errp, BDRV_OPT_FORCE_SHARE "=on can only be used with read-only images"); ret = -EINVAL; goto fail_opts; } if (file != NULL) { bdrv_refresh_filename(blk_bs(file)); filename = blk_bs(file)->filename; } else { /* * Caution: while qdict_get_try_str() is fine, getting * non-string types would require more care. When @options * come from -blockdev or blockdev_add, its members are typed * according to the QAPI schema, but when they come from * -drive, they're all QString. */ filename = qdict_get_try_str(options, "filename"); } if (drv->bdrv_needs_filename && (!filename || !filename[0])) { error_setg(errp, "The '%s' block driver requires a file name", drv->format_name); ret = -EINVAL; goto fail_opts; } trace_bdrv_open_common(bs, filename ?: "", bs->open_flags, drv->format_name); bs->read_only = !(bs->open_flags & BDRV_O_RDWR); if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) { if (!bs->read_only && bdrv_is_whitelisted(drv, true)) { ret = bdrv_apply_auto_read_only(bs, NULL, NULL); } else { ret = -ENOTSUP; } if (ret < 0) { error_setg(errp, !bs->read_only && bdrv_is_whitelisted(drv, true) ? "Driver '%s' can only be used for read-only devices" : "Driver '%s' is not whitelisted", drv->format_name); goto fail_opts; } } /* bdrv_new() and bdrv_close() make it so */ assert(qatomic_read(&bs->copy_on_read) == 0); if (bs->open_flags & BDRV_O_COPY_ON_READ) { if (!bs->read_only) { bdrv_enable_copy_on_read(bs); } else { error_setg(errp, "Can't use copy-on-read on read-only device"); ret = -EINVAL; goto fail_opts; } } discard = qemu_opt_get(opts, BDRV_OPT_DISCARD); if (discard != NULL) { if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) { error_setg(errp, "Invalid discard option"); ret = -EINVAL; goto fail_opts; } } bs->detect_zeroes = bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err); if (local_err) { error_propagate(errp, local_err); ret = -EINVAL; goto fail_opts; } if (filename != NULL) { pstrcpy(bs->filename, sizeof(bs->filename), filename); } else { bs->filename[0] = '\0'; } pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename); /* Open the image, either directly or using a protocol */ open_flags = bdrv_open_flags(bs, bs->open_flags); node_name = qemu_opt_get(opts, "node-name"); assert(!drv->bdrv_file_open || file == NULL); ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp); if (ret < 0) { goto fail_opts; } qemu_opts_del(opts); return 0; fail_opts: qemu_opts_del(opts); return ret; } static QDict *parse_json_filename(const char *filename, Error **errp) { QObject *options_obj; QDict *options; int ret; ret = strstart(filename, "json:", &filename); assert(ret); options_obj = qobject_from_json(filename, errp); if (!options_obj) { error_prepend(errp, "Could not parse the JSON options: "); return NULL; } options = qobject_to(QDict, options_obj); if (!options) { qobject_unref(options_obj); error_setg(errp, "Invalid JSON object given"); return NULL; } qdict_flatten(options); return options; } static void parse_json_protocol(QDict *options, const char **pfilename, Error **errp) { QDict *json_options; Error *local_err = NULL; /* Parse json: pseudo-protocol */ if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) { return; } json_options = parse_json_filename(*pfilename, &local_err); if (local_err) { error_propagate(errp, local_err); return; } /* Options given in the filename have lower priority than options * specified directly */ qdict_join(options, json_options, false); qobject_unref(json_options); *pfilename = NULL; } /* * Fills in default options for opening images and converts the legacy * filename/flags pair to option QDict entries. * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a * block driver has been specified explicitly. */ static int bdrv_fill_options(QDict **options, const char *filename, int *flags, Error **errp) { const char *drvname; bool protocol = *flags & BDRV_O_PROTOCOL; bool parse_filename = false; BlockDriver *drv = NULL; Error *local_err = NULL; /* * Caution: while qdict_get_try_str() is fine, getting non-string * types would require more care. When @options come from * -blockdev or blockdev_add, its members are typed according to * the QAPI schema, but when they come from -drive, they're all * QString. */ drvname = qdict_get_try_str(*options, "driver"); if (drvname) { drv = bdrv_find_format(drvname); if (!drv) { error_setg(errp, "Unknown driver '%s'", drvname); return -ENOENT; } /* If the user has explicitly specified the driver, this choice should * override the BDRV_O_PROTOCOL flag */ protocol = drv->bdrv_file_open; } if (protocol) { *flags |= BDRV_O_PROTOCOL; } else { *flags &= ~BDRV_O_PROTOCOL; } /* Translate cache options from flags into options */ update_options_from_flags(*options, *flags); /* Fetch the file name from the options QDict if necessary */ if (protocol && filename) { if (!qdict_haskey(*options, "filename")) { qdict_put_str(*options, "filename", filename); parse_filename = true; } else { error_setg(errp, "Can't specify 'file' and 'filename' options at " "the same time"); return -EINVAL; } } /* Find the right block driver */ /* See cautionary note on accessing @options above */ filename = qdict_get_try_str(*options, "filename"); if (!drvname && protocol) { if (filename) { drv = bdrv_find_protocol(filename, parse_filename, errp); if (!drv) { return -EINVAL; } drvname = drv->format_name; qdict_put_str(*options, "driver", drvname); } else { error_setg(errp, "Must specify either driver or file"); return -EINVAL; } } assert(drv || !protocol); /* Driver-specific filename parsing */ if (drv && drv->bdrv_parse_filename && parse_filename) { drv->bdrv_parse_filename(filename, *options, &local_err); if (local_err) { error_propagate(errp, local_err); return -EINVAL; } if (!drv->bdrv_needs_filename) { qdict_del(*options, "filename"); } } return 0; } static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q, uint64_t new_used_perm, uint64_t new_shared_perm, GSList *ignore_children, Error **errp); typedef struct BlockReopenQueueEntry { bool prepared; bool perms_checked; BDRVReopenState state; QTAILQ_ENTRY(BlockReopenQueueEntry) entry; } BlockReopenQueueEntry; /* * Return the flags that @bs will have after the reopens in @q have * successfully completed. If @q is NULL (or @bs is not contained in @q), * return the current flags. */ static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs) { BlockReopenQueueEntry *entry; if (q != NULL) { QTAILQ_FOREACH(entry, q, entry) { if (entry->state.bs == bs) { return entry->state.flags; } } } return bs->open_flags; } /* Returns whether the image file can be written to after the reopen queue @q * has been successfully applied, or right now if @q is NULL. */ static bool bdrv_is_writable_after_reopen(BlockDriverState *bs, BlockReopenQueue *q) { int flags = bdrv_reopen_get_flags(q, bs); return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR; } /* * Return whether the BDS can be written to. This is not necessarily * the same as !bdrv_is_read_only(bs), as inactivated images may not * be written to but do not count as read-only images. */ bool bdrv_is_writable(BlockDriverState *bs) { return bdrv_is_writable_after_reopen(bs, NULL); } static char *bdrv_child_user_desc(BdrvChild *c) { if (c->klass->get_parent_desc) { return c->klass->get_parent_desc(c); } return g_strdup("another user"); } static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp) { g_autofree char *user = NULL; g_autofree char *perm_names = NULL; if ((b->perm & a->shared_perm) == b->perm) { return true; } perm_names = bdrv_perm_names(b->perm & ~a->shared_perm); user = bdrv_child_user_desc(a); error_setg(errp, "Conflicts with use by %s as '%s', which does not " "allow '%s' on %s", user, a->name, perm_names, bdrv_get_node_name(b->bs)); return false; } static bool bdrv_parent_perms_conflict(BlockDriverState *bs, GSList *ignore_children, Error **errp) { BdrvChild *a, *b; /* * During the loop we'll look at each pair twice. That's correct because * bdrv_a_allow_b() is asymmetric and we should check each pair in both * directions. */ QLIST_FOREACH(a, &bs->parents, next_parent) { if (g_slist_find(ignore_children, a)) { continue; } QLIST_FOREACH(b, &bs->parents, next_parent) { if (a == b || g_slist_find(ignore_children, b)) { continue; } if (!bdrv_a_allow_b(a, b, errp)) { return true; } } } return false; } static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs, BdrvChild *c, BdrvChildRole role, BlockReopenQueue *reopen_queue, uint64_t parent_perm, uint64_t parent_shared, uint64_t *nperm, uint64_t *nshared) { assert(bs->drv && bs->drv->bdrv_child_perm); bs->drv->bdrv_child_perm(bs, c, role, reopen_queue, parent_perm, parent_shared, nperm, nshared); /* TODO Take force_share from reopen_queue */ if (child_bs && child_bs->force_share) { *nshared = BLK_PERM_ALL; } } /* * Adds the whole subtree of @bs (including @bs itself) to the @list (except for * nodes that are already in the @list, of course) so that final list is * topologically sorted. Return the result (GSList @list object is updated, so * don't use old reference after function call). * * On function start @list must be already topologically sorted and for any node * in the @list the whole subtree of the node must be in the @list as well. The * simplest way to satisfy this criteria: use only result of * bdrv_topological_dfs() or NULL as @list parameter. */ static GSList *bdrv_topological_dfs(GSList *list, GHashTable *found, BlockDriverState *bs) { BdrvChild *child; g_autoptr(GHashTable) local_found = NULL; if (!found) { assert(!list); found = local_found = g_hash_table_new(NULL, NULL); } if (g_hash_table_contains(found, bs)) { return list; } g_hash_table_add(found, bs); QLIST_FOREACH(child, &bs->children, next) { list = bdrv_topological_dfs(list, found, child->bs); } return g_slist_prepend(list, bs); } static void bdrv_child_set_perm_commit(void *opaque) { BdrvChild *c = opaque; c->has_backup_perm = false; } static void bdrv_child_set_perm_abort(void *opaque) { BdrvChild *c = opaque; /* * We may have child->has_backup_perm unset at this point, as in case of * _check_ stage of permission update failure we may _check_ not the whole * subtree. Still, _abort_ is called on the whole subtree anyway. */ if (c->has_backup_perm) { c->perm = c->backup_perm; c->shared_perm = c->backup_shared_perm; c->has_backup_perm = false; } } static TransactionActionDrv bdrv_child_set_pem_drv = { .abort = bdrv_child_set_perm_abort, .commit = bdrv_child_set_perm_commit, }; /* * With tran=NULL needs to be followed by direct call to either * bdrv_child_set_perm_commit() or bdrv_child_set_perm_abort(). * * With non-NULL tran needs to be followed by tran_abort() or tran_commit() * instead. */ static void bdrv_child_set_perm_safe(BdrvChild *c, uint64_t perm, uint64_t shared, Transaction *tran) { if (!c->has_backup_perm) { c->has_backup_perm = true; c->backup_perm = c->perm; c->backup_shared_perm = c->shared_perm; } /* * Note: it's OK if c->has_backup_perm was already set, as we can find the * same c twice during check_perm procedure */ c->perm = perm; c->shared_perm = shared; if (tran) { tran_add(tran, &bdrv_child_set_pem_drv, c); } } static void bdrv_drv_set_perm_commit(void *opaque) { BlockDriverState *bs = opaque; uint64_t cumulative_perms, cumulative_shared_perms; if (bs->drv->bdrv_set_perm) { bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms); bs->drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms); } } static void bdrv_drv_set_perm_abort(void *opaque) { BlockDriverState *bs = opaque; if (bs->drv->bdrv_abort_perm_update) { bs->drv->bdrv_abort_perm_update(bs); } } TransactionActionDrv bdrv_drv_set_perm_drv = { .abort = bdrv_drv_set_perm_abort, .commit = bdrv_drv_set_perm_commit, }; static int bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared_perm, Transaction *tran, Error **errp) { if (!bs->drv) { return 0; } if (bs->drv->bdrv_check_perm) { int ret = bs->drv->bdrv_check_perm(bs, perm, shared_perm, errp); if (ret < 0) { return ret; } } if (tran) { tran_add(tran, &bdrv_drv_set_perm_drv, bs); } return 0; } typedef struct BdrvReplaceChildState { BdrvChild *child; BlockDriverState *old_bs; } BdrvReplaceChildState; static void bdrv_replace_child_commit(void *opaque) { BdrvReplaceChildState *s = opaque; bdrv_unref(s->old_bs); } static void bdrv_replace_child_abort(void *opaque) { BdrvReplaceChildState *s = opaque; BlockDriverState *new_bs = s->child->bs; /* old_bs reference is transparently moved from @s to @s->child */ bdrv_replace_child_noperm(s->child, s->old_bs); bdrv_unref(new_bs); } static TransactionActionDrv bdrv_replace_child_drv = { .commit = bdrv_replace_child_commit, .abort = bdrv_replace_child_abort, .clean = g_free, }; /* * bdrv_replace_child_safe * * Note: real unref of old_bs is done only on commit. */ static void bdrv_replace_child_safe(BdrvChild *child, BlockDriverState *new_bs, Transaction *tran) { BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1); *s = (BdrvReplaceChildState) { .child = child, .old_bs = child->bs, }; tran_add(tran, &bdrv_replace_child_drv, s); if (new_bs) { bdrv_ref(new_bs); } bdrv_replace_child_noperm(child, new_bs); /* old_bs reference is transparently moved from @child to @s */ } /* * Check whether permissions on this node can be changed in a way that * @cumulative_perms and @cumulative_shared_perms are the new cumulative * permissions of all its parents. This involves checking whether all necessary * permission changes to child nodes can be performed. * * A call to this function must always be followed by a call to bdrv_set_perm() * or bdrv_abort_perm_update(). */ static int bdrv_node_check_perm(BlockDriverState *bs, BlockReopenQueue *q, uint64_t cumulative_perms, uint64_t cumulative_shared_perms, GSList *ignore_children, Transaction *tran, Error **errp) { BlockDriver *drv = bs->drv; BdrvChild *c; int ret; /* Write permissions never work with read-only images */ if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && !bdrv_is_writable_after_reopen(bs, q)) { if (!bdrv_is_writable_after_reopen(bs, NULL)) { error_setg(errp, "Block node is read-only"); } else { uint64_t current_perms, current_shared; bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared); if (current_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) { error_setg(errp, "Cannot make block node read-only, there is " "a writer on it"); } else { error_setg(errp, "Cannot make block node read-only and create " "a writer on it"); } } return -EPERM; } /* * Unaligned requests will automatically be aligned to bl.request_alignment * and without RESIZE we can't extend requests to write to space beyond the * end of the image, so it's required that the image size is aligned. */ if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && !(cumulative_perms & BLK_PERM_RESIZE)) { if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) { error_setg(errp, "Cannot get 'write' permission without 'resize': " "Image size is not a multiple of request " "alignment"); return -EPERM; } } /* Check this node */ if (!drv) { return 0; } ret = bdrv_drv_set_perm(bs, cumulative_perms, cumulative_shared_perms, tran, errp); if (ret < 0) { return ret; } /* Drivers that never have children can omit .bdrv_child_perm() */ if (!drv->bdrv_child_perm) { assert(QLIST_EMPTY(&bs->children)); return 0; } /* Check all children */ QLIST_FOREACH(c, &bs->children, next) { uint64_t cur_perm, cur_shared; bdrv_child_perm(bs, c->bs, c, c->role, q, cumulative_perms, cumulative_shared_perms, &cur_perm, &cur_shared); bdrv_child_set_perm_safe(c, cur_perm, cur_shared, tran); } return 0; } /* * If use_cumulative_perms is true, use cumulative_perms and * cumulative_shared_perms for first element of the list. Otherwise just refresh * all permissions. */ static int bdrv_check_perm_common(GSList *list, BlockReopenQueue *q, bool use_cumulative_perms, uint64_t cumulative_perms, uint64_t cumulative_shared_perms, GSList *ignore_children, Transaction *tran, Error **errp) { int ret; BlockDriverState *bs; if (use_cumulative_perms) { bs = list->data; ret = bdrv_node_check_perm(bs, q, cumulative_perms, cumulative_shared_perms, ignore_children, tran, errp); if (ret < 0) { return ret; } list = list->next; } for ( ; list; list = list->next) { bs = list->data; if (bdrv_parent_perms_conflict(bs, ignore_children, errp)) { return -EINVAL; } bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms); ret = bdrv_node_check_perm(bs, q, cumulative_perms, cumulative_shared_perms, ignore_children, tran, errp); if (ret < 0) { return ret; } } return 0; } static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q, uint64_t cumulative_perms, uint64_t cumulative_shared_perms, GSList *ignore_children, Error **errp) { g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs); return bdrv_check_perm_common(list, q, true, cumulative_perms, cumulative_shared_perms, ignore_children, NULL, errp); } static int bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran, Error **errp) { return bdrv_check_perm_common(list, q, false, 0, 0, NULL, tran, errp); } /* * Notifies drivers that after a previous bdrv_check_perm() call, the * permission update is not performed and any preparations made for it (e.g. * taken file locks) need to be undone. */ static void bdrv_node_abort_perm_update(BlockDriverState *bs) { BlockDriver *drv = bs->drv; BdrvChild *c; if (!drv) { return; } bdrv_drv_set_perm_abort(bs); QLIST_FOREACH(c, &bs->children, next) { bdrv_child_set_perm_abort(c); } } static void bdrv_list_abort_perm_update(GSList *list) { for ( ; list; list = list->next) { bdrv_node_abort_perm_update((BlockDriverState *)list->data); } } static void bdrv_abort_perm_update(BlockDriverState *bs) { g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs); return bdrv_list_abort_perm_update(list); } static void bdrv_node_set_perm(BlockDriverState *bs) { BlockDriver *drv = bs->drv; BdrvChild *c; if (!drv) { return; } bdrv_drv_set_perm_commit(bs); /* Drivers that never have children can omit .bdrv_child_perm() */ if (!drv->bdrv_child_perm) { assert(QLIST_EMPTY(&bs->children)); return; } /* Update all children */ QLIST_FOREACH(c, &bs->children, next) { bdrv_child_set_perm_commit(c); } } static void bdrv_list_set_perm(GSList *list) { for ( ; list; list = list->next) { bdrv_node_set_perm((BlockDriverState *)list->data); } } static void bdrv_set_perm(BlockDriverState *bs) { g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs); return bdrv_list_set_perm(list); } void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm, uint64_t *shared_perm) { BdrvChild *c; uint64_t cumulative_perms = 0; uint64_t cumulative_shared_perms = BLK_PERM_ALL; QLIST_FOREACH(c, &bs->parents, next_parent) { cumulative_perms |= c->perm; cumulative_shared_perms &= c->shared_perm; } *perm = cumulative_perms; *shared_perm = cumulative_shared_perms; } char *bdrv_perm_names(uint64_t perm) { struct perm_name { uint64_t perm; const char *name; } permissions[] = { { BLK_PERM_CONSISTENT_READ, "consistent read" }, { BLK_PERM_WRITE, "write" }, { BLK_PERM_WRITE_UNCHANGED, "write unchanged" }, { BLK_PERM_RESIZE, "resize" }, { BLK_PERM_GRAPH_MOD, "change children" }, { 0, NULL } }; GString *result = g_string_sized_new(30); struct perm_name *p; for (p = permissions; p->name; p++) { if (perm & p->perm) { if (result->len > 0) { g_string_append(result, ", "); } g_string_append(result, p->name); } } return g_string_free(result, FALSE); } /* * Checks whether a new reference to @bs can be added if the new user requires * @new_used_perm/@new_shared_perm as its permissions. If @ignore_children is * set, the BdrvChild objects in this list are ignored in the calculations; * this allows checking permission updates for an existing reference. * * Needs to be followed by a call to either bdrv_set_perm() or * bdrv_abort_perm_update(). */ static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q, uint64_t new_used_perm, uint64_t new_shared_perm, GSList *ignore_children, Error **errp) { BdrvChild *c; uint64_t cumulative_perms = new_used_perm; uint64_t cumulative_shared_perms = new_shared_perm; /* There is no reason why anyone couldn't tolerate write_unchanged */ assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED); QLIST_FOREACH(c, &bs->parents, next_parent) { if (g_slist_find(ignore_children, c)) { continue; } if ((new_used_perm & c->shared_perm) != new_used_perm) { char *user = bdrv_child_user_desc(c); char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm); error_setg(errp, "Conflicts with use by %s as '%s', which does not " "allow '%s' on %s", user, c->name, perm_names, bdrv_get_node_name(c->bs)); g_free(user); g_free(perm_names); return -EPERM; } if ((c->perm & new_shared_perm) != c->perm) { char *user = bdrv_child_user_desc(c); char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm); error_setg(errp, "Conflicts with use by %s as '%s', which uses " "'%s' on %s", user, c->name, perm_names, bdrv_get_node_name(c->bs)); g_free(user); g_free(perm_names); return -EPERM; } cumulative_perms |= c->perm; cumulative_shared_perms &= c->shared_perm; } return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_perms, ignore_children, errp); } static int bdrv_refresh_perms(BlockDriverState *bs, Error **errp) { int ret; Transaction *tran = tran_new(); g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs); ret = bdrv_list_refresh_perms(list, NULL, tran, errp); tran_finalize(tran, ret); return ret; } int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared, Error **errp) { Error *local_err = NULL; Transaction *tran = tran_new(); int ret; bdrv_child_set_perm_safe(c, perm, shared, tran); ret = bdrv_refresh_perms(c->bs, &local_err); tran_finalize(tran, ret); if (ret < 0) { if ((perm & ~c->perm) || (c->shared_perm & ~shared)) { /* tighten permissions */ error_propagate(errp, local_err); } else { /* * Our caller may intend to only loosen restrictions and * does not expect this function to fail. Errors are not * fatal in such a case, so we can just hide them from our * caller. */ error_free(local_err); ret = 0; } } return ret; } int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp) { uint64_t parent_perms, parent_shared; uint64_t perms, shared; bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared); bdrv_child_perm(bs, c->bs, c, c->role, NULL, parent_perms, parent_shared, &perms, &shared); return bdrv_child_try_set_perm(c, perms, shared, errp); } /* * Default implementation for .bdrv_child_perm() for block filters: * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the * filtered child. */ static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, BlockReopenQueue *reopen_queue, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared) { *nperm = perm & DEFAULT_PERM_PASSTHROUGH; *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED; } static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, BlockReopenQueue *reopen_queue, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared) { assert(role & BDRV_CHILD_COW); /* * We want consistent read from backing files if the parent needs it. * No other operations are performed on backing files. */ perm &= BLK_PERM_CONSISTENT_READ; /* * If the parent can deal with changing data, we're okay with a * writable and resizable backing file. * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too? */ if (shared & BLK_PERM_WRITE) { shared = BLK_PERM_WRITE | BLK_PERM_RESIZE; } else { shared = 0; } shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD | BLK_PERM_WRITE_UNCHANGED; if (bs->open_flags & BDRV_O_INACTIVE) { shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; } *nperm = perm; *nshared = shared; } static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, BlockReopenQueue *reopen_queue, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared) { int flags; assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)); flags = bdrv_reopen_get_flags(reopen_queue, bs); /* * Apart from the modifications below, the same permissions are * forwarded and left alone as for filters */ bdrv_filter_default_perms(bs, c, role, reopen_queue, perm, shared, &perm, &shared); if (role & BDRV_CHILD_METADATA) { /* Format drivers may touch metadata even if the guest doesn't write */ if (bdrv_is_writable_after_reopen(bs, reopen_queue)) { perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE; } /* * bs->file always needs to be consistent because of the * metadata. We can never allow other users to resize or write * to it. */ if (!(flags & BDRV_O_NO_IO)) { perm |= BLK_PERM_CONSISTENT_READ; } shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE); } if (role & BDRV_CHILD_DATA) { /* * Technically, everything in this block is a subset of the * BDRV_CHILD_METADATA path taken above, and so this could * be an "else if" branch. However, that is not obvious, and * this function is not performance critical, therefore we let * this be an independent "if". */ /* * We cannot allow other users to resize the file because the * format driver might have some assumptions about the size * (e.g. because it is stored in metadata, or because the file * is split into fixed-size data files). */ shared &= ~BLK_PERM_RESIZE; /* * WRITE_UNCHANGED often cannot be performed as such on the * data file. For example, the qcow2 driver may still need to * write copied clusters on copy-on-read. */ if (perm & BLK_PERM_WRITE_UNCHANGED) { perm |= BLK_PERM_WRITE; } /* * If the data file is written to, the format driver may * expect to be able to resize it by writing beyond the EOF. */ if (perm & BLK_PERM_WRITE) { perm |= BLK_PERM_RESIZE; } } if (bs->open_flags & BDRV_O_INACTIVE) { shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; } *nperm = perm; *nshared = shared; } void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, BlockReopenQueue *reopen_queue, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared) { if (role & BDRV_CHILD_FILTERED) { assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | BDRV_CHILD_COW))); bdrv_filter_default_perms(bs, c, role, reopen_queue, perm, shared, nperm, nshared); } else if (role & BDRV_CHILD_COW) { assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA))); bdrv_default_perms_for_cow(bs, c, role, reopen_queue, perm, shared, nperm, nshared); } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) { bdrv_default_perms_for_storage(bs, c, role, reopen_queue, perm, shared, nperm, nshared); } else { g_assert_not_reached(); } } uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm) { static const uint64_t permissions[] = { [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ, [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE, [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED, [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE, [BLOCK_PERMISSION_GRAPH_MOD] = BLK_PERM_GRAPH_MOD, }; QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX); QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1); assert(qapi_perm < BLOCK_PERMISSION__MAX); return permissions[qapi_perm]; } static void bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs) { BlockDriverState *old_bs = child->bs; int new_bs_quiesce_counter; int drain_saldo; assert(!child->frozen); if (old_bs && new_bs) { assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs)); } new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0); drain_saldo = new_bs_quiesce_counter - child->parent_quiesce_counter; /* * If the new child node is drained but the old one was not, flush * all outstanding requests to the old child node. */ while (drain_saldo > 0 && child->klass->drained_begin) { bdrv_parent_drained_begin_single(child, true); drain_saldo--; } if (old_bs) { /* Detach first so that the recursive drain sections coming from @child * are already gone and we only end the drain sections that came from * elsewhere. */ if (child->klass->detach) { child->klass->detach(child); } QLIST_REMOVE(child, next_parent); } child->bs = new_bs; if (new_bs) { QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); /* * Detaching the old node may have led to the new node's * quiesce_counter having been decreased. Not a problem, we * just need to recognize this here and then invoke * drained_end appropriately more often. */ assert(new_bs->quiesce_counter <= new_bs_quiesce_counter); drain_saldo += new_bs->quiesce_counter - new_bs_quiesce_counter; /* Attach only after starting new drained sections, so that recursive * drain sections coming from @child don't get an extra .drained_begin * callback. */ if (child->klass->attach) { child->klass->attach(child); } } /* * If the old child node was drained but the new one is not, allow * requests to come in only after the new node has been attached. */ while (drain_saldo < 0 && child->klass->drained_end) { bdrv_parent_drained_end_single(child); drain_saldo++; } } /* * Updates @child to change its reference to point to @new_bs, including * checking and applying the necessary permission updates both to the old node * and to @new_bs. * * NULL is passed as @new_bs for removing the reference before freeing @child. * * If @new_bs is not NULL, bdrv_check_perm() must be called beforehand, as this * function uses bdrv_set_perm() to update the permissions according to the new * reference that @new_bs gets. * * Callers must ensure that child->frozen is false. */ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) { BlockDriverState *old_bs = child->bs; /* Asserts that child->frozen == false */ bdrv_replace_child_noperm(child, new_bs); /* * Start with the new node's permissions. If @new_bs is a (direct * or indirect) child of @old_bs, we must complete the permission * update on @new_bs before we loosen the restrictions on @old_bs. * Otherwise, bdrv_check_perm() on @old_bs would re-initiate * updating the permissions of @new_bs, and thus not purely loosen * restrictions. */ if (new_bs) { bdrv_set_perm(new_bs); } if (old_bs) { /* * Update permissions for old node. We're just taking a parent away, so * we're loosening restrictions. Errors of permission update are not * fatal in this case, ignore them. */ bdrv_refresh_perms(old_bs, NULL); /* When the parent requiring a non-default AioContext is removed, the * node moves back to the main AioContext */ bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL); } } static void bdrv_child_free(void *opaque) { BdrvChild *c = opaque; g_free(c->name); g_free(c); } static void bdrv_remove_empty_child(BdrvChild *child) { assert(!child->bs); QLIST_SAFE_REMOVE(child, next); bdrv_child_free(child); } typedef struct BdrvAttachChildCommonState { BdrvChild **child; AioContext *old_parent_ctx; AioContext *old_child_ctx; } BdrvAttachChildCommonState; static void bdrv_attach_child_common_abort(void *opaque) { BdrvAttachChildCommonState *s = opaque; BdrvChild *child = *s->child; BlockDriverState *bs = child->bs; bdrv_replace_child_noperm(child, NULL); if (bdrv_get_aio_context(bs) != s->old_child_ctx) { bdrv_try_set_aio_context(bs, s->old_child_ctx, &error_abort); } if (bdrv_child_get_parent_aio_context(child) != s->old_parent_ctx) { GSList *ignore = g_slist_prepend(NULL, child); child->klass->can_set_aio_ctx(child, s->old_parent_ctx, &ignore, &error_abort); g_slist_free(ignore); ignore = g_slist_prepend(NULL, child); child->klass->set_aio_ctx(child, s->old_parent_ctx, &ignore); g_slist_free(ignore); } bdrv_unref(bs); bdrv_remove_empty_child(child); *s->child = NULL; } static TransactionActionDrv bdrv_attach_child_common_drv = { .abort = bdrv_attach_child_common_abort, .clean = g_free, }; /* * Common part of attaching bdrv child to bs or to blk or to job */ static int bdrv_attach_child_common(BlockDriverState *child_bs, const char *child_name, const BdrvChildClass *child_class, BdrvChildRole child_role, uint64_t perm, uint64_t shared_perm, void *opaque, BdrvChild **child, Transaction *tran, Error **errp) { BdrvChild *new_child; AioContext *parent_ctx; AioContext *child_ctx = bdrv_get_aio_context(child_bs); assert(child); assert(*child == NULL); new_child = g_new(BdrvChild, 1); *new_child = (BdrvChild) { .bs = NULL, .name = g_strdup(child_name), .klass = child_class, .role = child_role, .perm = perm, .shared_perm = shared_perm, .opaque = opaque, }; /* * If the AioContexts don't match, first try to move the subtree of * child_bs into the AioContext of the new parent. If this doesn't work, * try moving the parent into the AioContext of child_bs instead. */ parent_ctx = bdrv_child_get_parent_aio_context(new_child); if (child_ctx != parent_ctx) { Error *local_err = NULL; int ret = bdrv_try_set_aio_context(child_bs, parent_ctx, &local_err); if (ret < 0 && child_class->can_set_aio_ctx) { GSList *ignore = g_slist_prepend(NULL, new_child); if (child_class->can_set_aio_ctx(new_child, child_ctx, &ignore, NULL)) { error_free(local_err); ret = 0; g_slist_free(ignore); ignore = g_slist_prepend(NULL, new_child); child_class->set_aio_ctx(new_child, child_ctx, &ignore); } g_slist_free(ignore); } if (ret < 0) { error_propagate(errp, local_err); bdrv_remove_empty_child(new_child); return ret; } } bdrv_ref(child_bs); bdrv_replace_child_noperm(new_child, child_bs); *child = new_child; BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1); *s = (BdrvAttachChildCommonState) { .child = child, .old_parent_ctx = parent_ctx, .old_child_ctx = child_ctx, }; tran_add(tran, &bdrv_attach_child_common_drv, s); return 0; } static int bdrv_attach_child_noperm(BlockDriverState *parent_bs, BlockDriverState *child_bs, const char *child_name, const BdrvChildClass *child_class, BdrvChildRole child_role, BdrvChild **child, Transaction *tran, Error **errp) { int ret; uint64_t perm, shared_perm; assert(parent_bs->drv); bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm); bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL, perm, shared_perm, &perm, &shared_perm); ret = bdrv_attach_child_common(child_bs, child_name, child_class, child_role, perm, shared_perm, parent_bs, child, tran, errp); if (ret < 0) { return ret; } QLIST_INSERT_HEAD(&parent_bs->children, *child, next); /* * child is removed in bdrv_attach_child_common_abort(), so don't care to * abort this change separately. */ return 0; } static void bdrv_detach_child(BdrvChild *child) { bdrv_replace_child(child, NULL); bdrv_remove_empty_child(child); } /* * This function steals the reference to child_bs from the caller. * That reference is later dropped by bdrv_root_unref_child(). * * On failure NULL is returned, errp is set and the reference to * child_bs is also dropped. * * The caller must hold the AioContext lock @child_bs, but not that of @ctx * (unless @child_bs is already in @ctx). */ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, const char *child_name, const BdrvChildClass *child_class, BdrvChildRole child_role, uint64_t perm, uint64_t shared_perm, void *opaque, Error **errp) { int ret; BdrvChild *child = NULL; Transaction *tran = tran_new(); ret = bdrv_attach_child_common(child_bs, child_name, child_class, child_role, perm, shared_perm, opaque, &child, tran, errp); if (ret < 0) { bdrv_unref(child_bs); return NULL; } ret = bdrv_refresh_perms(child_bs, errp); tran_finalize(tran, ret); bdrv_unref(child_bs); return child; } /* * This function transfers the reference to child_bs from the caller * to parent_bs. That reference is later dropped by parent_bs on * bdrv_close() or if someone calls bdrv_unref_child(). * * On failure NULL is returned, errp is set and the reference to * child_bs is also dropped. * * If @parent_bs and @child_bs are in different AioContexts, the caller must * hold the AioContext lock for @child_bs, but not for @parent_bs. */ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, BlockDriverState *child_bs, const char *child_name, const BdrvChildClass *child_class, BdrvChildRole child_role, Error **errp) { int ret; BdrvChild *child = NULL; Transaction *tran = tran_new(); ret = bdrv_attach_child_noperm(parent_bs, child_bs, child_name, child_class, child_role, &child, tran, errp); if (ret < 0) { goto out; } ret = bdrv_refresh_perms(parent_bs, errp); if (ret < 0) { goto out; } out: tran_finalize(tran, ret); bdrv_unref(child_bs); return child; } /* Callers must ensure that child->frozen is false. */ void bdrv_root_unref_child(BdrvChild *child) { BlockDriverState *child_bs; child_bs = child->bs; bdrv_detach_child(child); bdrv_unref(child_bs); } /** * Clear all inherits_from pointers from children and grandchildren of * @root that point to @root, where necessary. */ static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child) { BdrvChild *c; if (child->bs->inherits_from == root) { /* * Remove inherits_from only when the last reference between root and * child->bs goes away. */ QLIST_FOREACH(c, &root->children, next) { if (c != child && c->bs == child->bs) { break; } } if (c == NULL) { child->bs->inherits_from = NULL; } } QLIST_FOREACH(c, &child->bs->children, next) { bdrv_unset_inherits_from(root, c); } } /* Callers must ensure that child->frozen is false. */ void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child) { if (child == NULL) { return; } bdrv_unset_inherits_from(parent, child); bdrv_root_unref_child(child); } static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load) { BdrvChild *c; QLIST_FOREACH(c, &bs->parents, next_parent) { if (c->klass->change_media) { c->klass->change_media(c, load); } } } /* Return true if you can reach parent going through child->inherits_from * recursively. If parent or child are NULL, return false */ static bool bdrv_inherits_from_recursive(BlockDriverState *child, BlockDriverState *parent) { while (child && child != parent) { child = child->inherits_from; } return child != NULL; } /* * Return the BdrvChildRole for @bs's backing child. bs->backing is * mostly used for COW backing children (role = COW), but also for * filtered children (role = FILTERED | PRIMARY). */ static BdrvChildRole bdrv_backing_role(BlockDriverState *bs) { if (bs->drv && bs->drv->is_filter) { return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY; } else { return BDRV_CHILD_COW; } } /* * Sets the bs->backing link of a BDS. A new reference is created; callers * which don't need their own reference any more must call bdrv_unref(). */ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, Error **errp) { int ret = 0; bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) && bdrv_inherits_from_recursive(backing_hd, bs); if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) { return -EPERM; } if (backing_hd) { bdrv_ref(backing_hd); } if (bs->backing) { /* Cannot be frozen, we checked that above */ bdrv_unref_child(bs, bs->backing); bs->backing = NULL; } if (!backing_hd) { goto out; } bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_of_bds, bdrv_backing_role(bs), errp); if (!bs->backing) { ret = -EPERM; goto out; } /* If backing_hd was already part of bs's backing chain, and * inherits_from pointed recursively to bs then let's update it to * point directly to bs (else it will become NULL). */ if (update_inherits_from) { backing_hd->inherits_from = bs; } out: bdrv_refresh_limits(bs, NULL); return ret; } /* * Opens the backing file for a BlockDriverState if not yet open * * bdref_key specifies the key for the image's BlockdevRef in the options QDict. * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict * itself, all options starting with "${bdref_key}." are considered part of the * BlockdevRef. * * TODO Can this be unified with bdrv_open_image()? */ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options, const char *bdref_key, Error **errp) { char *backing_filename = NULL; char *bdref_key_dot; const char *reference = NULL; int ret = 0; bool implicit_backing = false; BlockDriverState *backing_hd; QDict *options; QDict *tmp_parent_options = NULL; Error *local_err = NULL; if (bs->backing != NULL) { goto free_exit; } /* NULL means an empty set of options */ if (parent_options == NULL) { tmp_parent_options = qdict_new(); parent_options = tmp_parent_options; } bs->open_flags &= ~BDRV_O_NO_BACKING; bdref_key_dot = g_strdup_printf("%s.", bdref_key); qdict_extract_subqdict(parent_options, &options, bdref_key_dot); g_free(bdref_key_dot); /* * Caution: while qdict_get_try_str() is fine, getting non-string * types would require more care. When @parent_options come from * -blockdev or blockdev_add, its members are typed according to * the QAPI schema, but when they come from -drive, they're all * QString. */ reference = qdict_get_try_str(parent_options, bdref_key); if (reference || qdict_haskey(options, "file.filename")) { /* keep backing_filename NULL */ } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { qobject_unref(options); goto free_exit; } else { if (qdict_size(options) == 0) { /* If the user specifies options that do not modify the * backing file's behavior, we might still consider it the * implicit backing file. But it's easier this way, and * just specifying some of the backing BDS's options is * only possible with -drive anyway (otherwise the QAPI * schema forces the user to specify everything). */ implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file); } backing_filename = bdrv_get_full_backing_filename(bs, &local_err); if (local_err) { ret = -EINVAL; error_propagate(errp, local_err); qobject_unref(options); goto free_exit; } } if (!bs->drv || !bs->drv->supports_backing) { ret = -EINVAL; error_setg(errp, "Driver doesn't support backing files"); qobject_unref(options); goto free_exit; } if (!reference && bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) { qdict_put_str(options, "driver", bs->backing_format); } backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs, &child_of_bds, bdrv_backing_role(bs), errp); if (!backing_hd) { bs->open_flags |= BDRV_O_NO_BACKING; error_prepend(errp, "Could not open backing file: "); ret = -EINVAL; goto free_exit; } if (implicit_backing) { bdrv_refresh_filename(backing_hd); pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), backing_hd->filename); } /* Hook up the backing file link; drop our reference, bs owns the * backing_hd reference now */ ret = bdrv_set_backing_hd(bs, backing_hd, errp); bdrv_unref(backing_hd); if (ret < 0) { goto free_exit; } qdict_del(parent_options, bdref_key); free_exit: g_free(backing_filename); qobject_unref(tmp_parent_options); return ret; } static BlockDriverState * bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key, BlockDriverState *parent, const BdrvChildClass *child_class, BdrvChildRole child_role, bool allow_none, Error **errp) { BlockDriverState *bs = NULL; QDict *image_options; char *bdref_key_dot; const char *reference; assert(child_class != NULL); bdref_key_dot = g_strdup_printf("%s.", bdref_key); qdict_extract_subqdict(options, &image_options, bdref_key_dot); g_free(bdref_key_dot); /* * Caution: while qdict_get_try_str() is fine, getting non-string * types would require more care. When @options come from * -blockdev or blockdev_add, its members are typed according to * the QAPI schema, but when they come from -drive, they're all * QString. */ reference = qdict_get_try_str(options, bdref_key); if (!filename && !reference && !qdict_size(image_options)) { if (!allow_none) { error_setg(errp, "A block device must be specified for \"%s\"", bdref_key); } qobject_unref(image_options); goto done; } bs = bdrv_open_inherit(filename, reference, image_options, 0, parent, child_class, child_role, errp); if (!bs) { goto done; } done: qdict_del(options, bdref_key); return bs; } /* * Opens a disk image whose options are given as BlockdevRef in another block * device's options. * * If allow_none is true, no image will be opened if filename is false and no * BlockdevRef is given. NULL will be returned, but errp remains unset. * * bdrev_key specifies the key for the image's BlockdevRef in the options QDict. * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict * itself, all options starting with "${bdref_key}." are considered part of the * BlockdevRef. * * The BlockdevRef will be removed from the options QDict. */ BdrvChild *bdrv_open_child(const char *filename, QDict *options, const char *bdref_key, BlockDriverState *parent, const BdrvChildClass *child_class, BdrvChildRole child_role, bool allow_none, Error **errp) { BlockDriverState *bs; bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class, child_role, allow_none, errp); if (bs == NULL) { return NULL; } return bdrv_attach_child(parent, bs, bdref_key, child_class, child_role, errp); } /* * TODO Future callers may need to specify parent/child_class in order for * option inheritance to work. Existing callers use it for the root node. */ BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp) { BlockDriverState *bs = NULL; QObject *obj = NULL; QDict *qdict = NULL; const char *reference = NULL; Visitor *v = NULL; if (ref->type == QTYPE_QSTRING) { reference = ref->u.reference; } else { BlockdevOptions *options = &ref->u.definition; assert(ref->type == QTYPE_QDICT); v = qobject_output_visitor_new(&obj); visit_type_BlockdevOptions(v, NULL, &options, &error_abort); visit_complete(v, &obj); qdict = qobject_to(QDict, obj); qdict_flatten(qdict); /* bdrv_open_inherit() defaults to the values in bdrv_flags (for * compatibility with other callers) rather than what we want as the * real defaults. Apply the defaults here instead. */ qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off"); qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off"); qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off"); qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off"); } bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp); obj = NULL; qobject_unref(obj); visit_free(v); return bs; } static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, int flags, QDict *snapshot_options, Error **errp) { /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */ char *tmp_filename = g_malloc0(PATH_MAX + 1); int64_t total_size; QemuOpts *opts = NULL; BlockDriverState *bs_snapshot = NULL; int ret; /* if snapshot, we create a temporary backing file and open it instead of opening 'filename' directly */ /* Get the required size from the image */ total_size = bdrv_getlength(bs); if (total_size < 0) { error_setg_errno(errp, -total_size, "Could not get image size"); goto out; } /* Create the temporary image */ ret = get_tmp_filename(tmp_filename, PATH_MAX + 1); if (ret < 0) { error_setg_errno(errp, -ret, "Could not get temporary filename"); goto out; } opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0, &error_abort); qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort); ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp); qemu_opts_del(opts); if (ret < 0) { error_prepend(errp, "Could not create temporary overlay '%s': ", tmp_filename); goto out; } /* Prepare options QDict for the temporary file */ qdict_put_str(snapshot_options, "file.driver", "file"); qdict_put_str(snapshot_options, "file.filename", tmp_filename); qdict_put_str(snapshot_options, "driver", "qcow2"); bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp); snapshot_options = NULL; if (!bs_snapshot) { goto out; } ret = bdrv_append(bs_snapshot, bs, errp); if (ret < 0) { bs_snapshot = NULL; goto out; } out: qobject_unref(snapshot_options); g_free(tmp_filename); return bs_snapshot; } /* * Opens a disk image (raw, qcow2, vmdk, ...) * * options is a QDict of options to pass to the block drivers, or NULL for an * empty set of options. The reference to the QDict belongs to the block layer * after the call (even on failure), so if the caller intends to reuse the * dictionary, it needs to use qobject_ref() before calling bdrv_open. * * If *pbs is NULL, a new BDS will be created with a pointer to it stored there. * If it is not NULL, the referenced BDS will be reused. * * The reference parameter may be used to specify an existing block device which * should be opened. If specified, neither options nor a filename may be given, * nor can an existing BDS be reused (that is, *pbs has to be NULL). */ static BlockDriverState *bdrv_open_inherit(const char *filename, const char *reference, QDict *options, int flags, BlockDriverState *parent, const BdrvChildClass *child_class, BdrvChildRole child_role, Error **errp) { int ret; BlockBackend *file = NULL; BlockDriverState *bs; BlockDriver *drv = NULL; BdrvChild *child; const char *drvname; const char *backing; Error *local_err = NULL; QDict *snapshot_options = NULL; int snapshot_flags = 0; assert(!child_class || !flags); assert(!child_class == !parent); if (reference) { bool options_non_empty = options ? qdict_size(options) : false; qobject_unref(options); if (filename || options_non_empty) { error_setg(errp, "Cannot reference an existing block device with " "additional options or a new filename"); return NULL; } bs = bdrv_lookup_bs(reference, reference, errp); if (!bs) { return NULL; } bdrv_ref(bs); return bs; } bs = bdrv_new(); /* NULL means an empty set of options */ if (options == NULL) { options = qdict_new(); } /* json: syntax counts as explicit options, as if in the QDict */ parse_json_protocol(options, &filename, &local_err); if (local_err) { goto fail; } bs->explicit_options = qdict_clone_shallow(options); if (child_class) { bool parent_is_format; if (parent->drv) { parent_is_format = parent->drv->is_format; } else { /* * parent->drv is not set yet because this node is opened for * (potential) format probing. That means that @parent is going * to be a format node. */ parent_is_format = true; } bs->inherits_from = parent; child_class->inherit_options(child_role, parent_is_format, &flags, options, parent->open_flags, parent->options); } ret = bdrv_fill_options(&options, filename, &flags, &local_err); if (ret < 0) { goto fail; } /* * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags. * Caution: getting a boolean member of @options requires care. * When @options come from -blockdev or blockdev_add, members are * typed according to the QAPI schema, but when they come from * -drive, they're all QString. */ if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") && !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) { flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR); } else { flags &= ~BDRV_O_RDWR; } if (flags & BDRV_O_SNAPSHOT) { snapshot_options = qdict_new(); bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options, flags, options); /* Let bdrv_backing_options() override "read-only" */ qdict_del(options, BDRV_OPT_READ_ONLY); bdrv_inherited_options(BDRV_CHILD_COW, true, &flags, options, flags, options); } bs->open_flags = flags; bs->options = options; options = qdict_clone_shallow(options); /* Find the right image format driver */ /* See cautionary note on accessing @options above */ drvname = qdict_get_try_str(options, "driver"); if (drvname) { drv = bdrv_find_format(drvname); if (!drv) { error_setg(errp, "Unknown driver: '%s'", drvname); goto fail; } } assert(drvname || !(flags & BDRV_O_PROTOCOL)); /* See cautionary note on accessing @options above */ backing = qdict_get_try_str(options, "backing"); if (qobject_to(QNull, qdict_get(options, "backing")) != NULL || (backing && *backing == '\0')) { if (backing) { warn_report("Use of \"backing\": \"\" is deprecated; " "use \"backing\": null instead"); } flags |= BDRV_O_NO_BACKING; qdict_del(bs->explicit_options, "backing"); qdict_del(bs->options, "backing"); qdict_del(options, "backing"); } /* Open image file without format layer. This BlockBackend is only used for * probing, the block drivers will do their own bdrv_open_child() for the * same BDS, which is why we put the node name back into options. */ if ((flags & BDRV_O_PROTOCOL) == 0) { BlockDriverState *file_bs; file_bs = bdrv_open_child_bs(filename, options, "file", bs, &child_of_bds, BDRV_CHILD_IMAGE, true, &local_err); if (local_err) { goto fail; } if (file_bs != NULL) { /* Not requesting BLK_PERM_CONSISTENT_READ because we're only * looking at the header to guess the image format. This works even * in cases where a guest would not see a consistent state. */ file = blk_new(bdrv_get_aio_context(file_bs), 0, BLK_PERM_ALL); blk_insert_bs(file, file_bs, &local_err); bdrv_unref(file_bs); if (local_err) { goto fail; } qdict_put_str(options, "file", bdrv_get_node_name(file_bs)); } } /* Image format probing */ bs->probed = !drv; if (!drv && file) { ret = find_image_format(file, filename, &drv, &local_err); if (ret < 0) { goto fail; } /* * This option update would logically belong in bdrv_fill_options(), * but we first need to open bs->file for the probing to work, while * opening bs->file already requires the (mostly) final set of options * so that cache mode etc. can be inherited. * * Adding the driver later is somewhat ugly, but it's not an option * that would ever be inherited, so it's correct. We just need to make * sure to update both bs->options (which has the full effective * options for bs) and options (which has file.* already removed). */ qdict_put_str(bs->options, "driver", drv->format_name); qdict_put_str(options, "driver", drv->format_name); } else if (!drv) { error_setg(errp, "Must specify either driver or file"); goto fail; } /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */ assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open); /* file must be NULL if a protocol BDS is about to be created * (the inverse results in an error message from bdrv_open_common()) */ assert(!(flags & BDRV_O_PROTOCOL) || !file); /* Open the image */ ret = bdrv_open_common(bs, file, options, &local_err); if (ret < 0) { goto fail; } if (file) { blk_unref(file); file = NULL; } /* If there is a backing file, use it */ if ((flags & BDRV_O_NO_BACKING) == 0) { ret = bdrv_open_backing_file(bs, options, "backing", &local_err); if (ret < 0) { goto close_and_fail; } } /* Remove all children options and references * from bs->options and bs->explicit_options */ QLIST_FOREACH(child, &bs->children, next) { char *child_key_dot; child_key_dot = g_strdup_printf("%s.", child->name); qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot); qdict_extract_subqdict(bs->options, NULL, child_key_dot); qdict_del(bs->explicit_options, child->name); qdict_del(bs->options, child->name); g_free(child_key_dot); } /* Check if any unknown options were used */ if (qdict_size(options) != 0) { const QDictEntry *entry = qdict_first(options); if (flags & BDRV_O_PROTOCOL) { error_setg(errp, "Block protocol '%s' doesn't support the option " "'%s'", drv->format_name, entry->key); } else { error_setg(errp, "Block format '%s' does not support the option '%s'", drv->format_name, entry->key); } goto close_and_fail; } bdrv_parent_cb_change_media(bs, true); qobject_unref(options); options = NULL; /* For snapshot=on, create a temporary qcow2 overlay. bs points to the * temporary snapshot afterwards. */ if (snapshot_flags) { BlockDriverState *snapshot_bs; snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags, snapshot_options, &local_err); snapshot_options = NULL; if (local_err) { goto close_and_fail; } /* We are not going to return bs but the overlay on top of it * (snapshot_bs); thus, we have to drop the strong reference to bs * (which we obtained by calling bdrv_new()). bs will not be deleted, * though, because the overlay still has a reference to it. */ bdrv_unref(bs); bs = snapshot_bs; } return bs; fail: blk_unref(file); qobject_unref(snapshot_options); qobject_unref(bs->explicit_options); qobject_unref(bs->options); qobject_unref(options); bs->options = NULL; bs->explicit_options = NULL; bdrv_unref(bs); error_propagate(errp, local_err); return NULL; close_and_fail: bdrv_unref(bs); qobject_unref(snapshot_options); qobject_unref(options); error_propagate(errp, local_err); return NULL; } BlockDriverState *bdrv_open(const char *filename, const char *reference, QDict *options, int flags, Error **errp) { return bdrv_open_inherit(filename, reference, options, flags, NULL, NULL, 0, errp); } /* Return true if the NULL-terminated @list contains @str */ static bool is_str_in_list(const char *str, const char *const *list) { if (str && list) { int i; for (i = 0; list[i] != NULL; i++) { if (!strcmp(str, list[i])) { return true; } } } return false; } /* * Check that every option set in @bs->options is also set in * @new_opts. * * Options listed in the common_options list and in * @bs->drv->mutable_opts are skipped. * * Return 0 on success, otherwise return -EINVAL and set @errp. */ static int bdrv_reset_options_allowed(BlockDriverState *bs, const QDict *new_opts, Error **errp) { const QDictEntry *e; /* These options are common to all block drivers and are handled * in bdrv_reopen_prepare() so they can be left out of @new_opts */ const char *const common_options[] = { "node-name", "discard", "cache.direct", "cache.no-flush", "read-only", "auto-read-only", "detect-zeroes", NULL }; for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) { if (!qdict_haskey(new_opts, e->key) && !is_str_in_list(e->key, common_options) && !is_str_in_list(e->key, bs->drv->mutable_opts)) { error_setg(errp, "Option '%s' cannot be reset " "to its default value", e->key); return -EINVAL; } } return 0; } /* * Returns true if @child can be reached recursively from @bs */ static bool bdrv_recurse_has_child(BlockDriverState *bs, BlockDriverState *child) { BdrvChild *c; if (bs == child) { return true; } QLIST_FOREACH(c, &bs->children, next) { if (bdrv_recurse_has_child(c->bs, child)) { return true; } } return false; } /* * Adds a BlockDriverState to a simple queue for an atomic, transactional * reopen of multiple devices. * * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT * already performed, or alternatively may be NULL a new BlockReopenQueue will * be created and initialized. This newly created BlockReopenQueue should be * passed back in for subsequent calls that are intended to be of the same * atomic 'set'. * * bs is the BlockDriverState to add to the reopen queue. * * options contains the changed options for the associated bs * (the BlockReopenQueue takes ownership) * * flags contains the open flags for the associated bs * * returns a pointer to bs_queue, which is either the newly allocated * bs_queue, or the existing bs_queue being used. * * bs must be drained between bdrv_reopen_queue() and bdrv_reopen_multiple(). */ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue, BlockDriverState *bs, QDict *options, const BdrvChildClass *klass, BdrvChildRole role, bool parent_is_format, QDict *parent_options, int parent_flags, bool keep_old_opts) { assert(bs != NULL); BlockReopenQueueEntry *bs_entry; BdrvChild *child; QDict *old_options, *explicit_options, *options_copy; int flags; QemuOpts *opts; /* Make sure that the caller remembered to use a drained section. This is * important to avoid graph changes between the recursive queuing here and * bdrv_reopen_multiple(). */ assert(bs->quiesce_counter > 0); if (bs_queue == NULL) { bs_queue = g_new0(BlockReopenQueue, 1); QTAILQ_INIT(bs_queue); } if (!options) { options = qdict_new(); } /* Check if this BlockDriverState is already in the queue */ QTAILQ_FOREACH(bs_entry, bs_queue, entry) { if (bs == bs_entry->state.bs) { break; } } /* * Precedence of options: * 1. Explicitly passed in options (highest) * 2. Retained from explicitly set options of bs * 3. Inherited from parent node * 4. Retained from effective options of bs */ /* Old explicitly set values (don't overwrite by inherited value) */ if (bs_entry || keep_old_opts) { old_options = qdict_clone_shallow(bs_entry ? bs_entry->state.explicit_options : bs->explicit_options); bdrv_join_options(bs, options, old_options); qobject_unref(old_options); } explicit_options = qdict_clone_shallow(options); /* Inherit from parent node */ if (parent_options) { flags = 0; klass->inherit_options(role, parent_is_format, &flags, options, parent_flags, parent_options); } else { flags = bdrv_get_flags(bs); } if (keep_old_opts) { /* Old values are used for options that aren't set yet */ old_options = qdict_clone_shallow(bs->options); bdrv_join_options(bs, options, old_options); qobject_unref(old_options); } /* We have the final set of options so let's update the flags */ options_copy = qdict_clone_shallow(options); opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); qemu_opts_absorb_qdict(opts, options_copy, NULL); update_flags_from_options(&flags, opts); qemu_opts_del(opts); qobject_unref(options_copy); /* bdrv_open_inherit() sets and clears some additional flags internally */ flags &= ~BDRV_O_PROTOCOL; if (flags & BDRV_O_RDWR) { flags |= BDRV_O_ALLOW_RDWR; } if (!bs_entry) { bs_entry = g_new0(BlockReopenQueueEntry, 1); QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry); } else { qobject_unref(bs_entry->state.options); qobject_unref(bs_entry->state.explicit_options); } bs_entry->state.bs = bs; bs_entry->state.options = options; bs_entry->state.explicit_options = explicit_options; bs_entry->state.flags = flags; /* This needs to be overwritten in bdrv_reopen_prepare() */ bs_entry->state.perm = UINT64_MAX; bs_entry->state.shared_perm = 0; /* * If keep_old_opts is false then it means that unspecified * options must be reset to their original value. We don't allow * resetting 'backing' but we need to know if the option is * missing in order to decide if we have to return an error. */ if (!keep_old_opts) { bs_entry->state.backing_missing = !qdict_haskey(options, "backing") && !qdict_haskey(options, "backing.driver"); } QLIST_FOREACH(child, &bs->children, next) { QDict *new_child_options = NULL; bool child_keep_old = keep_old_opts; /* reopen can only change the options of block devices that were * implicitly created and inherited options. For other (referenced) * block devices, a syntax like "backing.foo" results in an error. */ if (child->bs->inherits_from != bs) { continue; } /* Check if the options contain a child reference */ if (qdict_haskey(options, child->name)) { const char *childref = qdict_get_try_str(options, child->name); /* * The current child must not be reopened if the child * reference is null or points to a different node. */ if (g_strcmp0(childref, child->bs->node_name)) { continue; } /* * If the child reference points to the current child then * reopen it with its existing set of options (note that * it can still inherit new options from the parent). */ child_keep_old = true; } else { /* Extract child options ("child-name.*") */ char *child_key_dot = g_strdup_printf("%s.", child->name); qdict_extract_subqdict(explicit_options, NULL, child_key_dot); qdict_extract_subqdict(options, &new_child_options, child_key_dot); g_free(child_key_dot); } bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options, child->klass, child->role, bs->drv->is_format, options, flags, child_keep_old); } return bs_queue; } BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue, BlockDriverState *bs, QDict *options, bool keep_old_opts) { return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false, NULL, 0, keep_old_opts); } /* * Reopen multiple BlockDriverStates atomically & transactionally. * * The queue passed in (bs_queue) must have been built up previous * via bdrv_reopen_queue(). * * Reopens all BDS specified in the queue, with the appropriate * flags. All devices are prepared for reopen, and failure of any * device will cause all device changes to be abandoned, and intermediate * data cleaned up. * * If all devices prepare successfully, then the changes are committed * to all devices. * * All affected nodes must be drained between bdrv_reopen_queue() and * bdrv_reopen_multiple(). */ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) { int ret = -1; BlockReopenQueueEntry *bs_entry, *next; assert(bs_queue != NULL); QTAILQ_FOREACH(bs_entry, bs_queue, entry) { assert(bs_entry->state.bs->quiesce_counter > 0); if (bdrv_reopen_prepare(&bs_entry->state, bs_queue, errp)) { goto cleanup; } bs_entry->prepared = true; } QTAILQ_FOREACH(bs_entry, bs_queue, entry) { BDRVReopenState *state = &bs_entry->state; ret = bdrv_check_perm(state->bs, bs_queue, state->perm, state->shared_perm, NULL, errp); if (ret < 0) { goto cleanup_perm; } /* Check if new_backing_bs would accept the new permissions */ if (state->replace_backing_bs && state->new_backing_bs) { uint64_t nperm, nshared; bdrv_child_perm(state->bs, state->new_backing_bs, NULL, bdrv_backing_role(state->bs), bs_queue, state->perm, state->shared_perm, &nperm, &nshared); ret = bdrv_check_update_perm(state->new_backing_bs, NULL, nperm, nshared, NULL, errp); if (ret < 0) { goto cleanup_perm; } } bs_entry->perms_checked = true; } /* * If we reach this point, we have success and just need to apply the * changes. * * Reverse order is used to comfort qcow2 driver: on commit it need to write * IN_USE flag to the image, to mark bitmaps in the image as invalid. But * children are usually goes after parents in reopen-queue, so go from last * to first element. */ QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { bdrv_reopen_commit(&bs_entry->state); } ret = 0; cleanup_perm: QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { BDRVReopenState *state = &bs_entry->state; if (!bs_entry->perms_checked) { continue; } if (ret == 0) { uint64_t perm, shared; bdrv_get_cumulative_perm(state->bs, &perm, &shared); assert(perm == state->perm); assert(shared == state->shared_perm); bdrv_set_perm(state->bs); } else { bdrv_abort_perm_update(state->bs); if (state->replace_backing_bs && state->new_backing_bs) { bdrv_abort_perm_update(state->new_backing_bs); } } } if (ret == 0) { QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { BlockDriverState *bs = bs_entry->state.bs; if (bs->drv->bdrv_reopen_commit_post) bs->drv->bdrv_reopen_commit_post(&bs_entry->state); } } cleanup: QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { if (ret) { if (bs_entry->prepared) { bdrv_reopen_abort(&bs_entry->state); } qobject_unref(bs_entry->state.explicit_options); qobject_unref(bs_entry->state.options); } if (bs_entry->state.new_backing_bs) { bdrv_unref(bs_entry->state.new_backing_bs); } g_free(bs_entry); } g_free(bs_queue); return ret; } int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only, Error **errp) { int ret; BlockReopenQueue *queue; QDict *opts = qdict_new(); qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only); bdrv_subtree_drained_begin(bs); queue = bdrv_reopen_queue(NULL, bs, opts, true); ret = bdrv_reopen_multiple(queue, errp); bdrv_subtree_drained_end(bs); return ret; } static BlockReopenQueueEntry *find_parent_in_reopen_queue(BlockReopenQueue *q, BdrvChild *c) { BlockReopenQueueEntry *entry; QTAILQ_FOREACH(entry, q, entry) { BlockDriverState *bs = entry->state.bs; BdrvChild *child; QLIST_FOREACH(child, &bs->children, next) { if (child == c) { return entry; } } } return NULL; } static void bdrv_reopen_perm(BlockReopenQueue *q, BlockDriverState *bs, uint64_t *perm, uint64_t *shared) { BdrvChild *c; BlockReopenQueueEntry *parent; uint64_t cumulative_perms = 0; uint64_t cumulative_shared_perms = BLK_PERM_ALL; QLIST_FOREACH(c, &bs->parents, next_parent) { parent = find_parent_in_reopen_queue(q, c); if (!parent) { cumulative_perms |= c->perm; cumulative_shared_perms &= c->shared_perm; } else { uint64_t nperm, nshared; bdrv_child_perm(parent->state.bs, bs, c, c->role, q, parent->state.perm, parent->state.shared_perm, &nperm, &nshared); cumulative_perms |= nperm; cumulative_shared_perms &= nshared; } } *perm = cumulative_perms; *shared = cumulative_shared_perms; } static bool bdrv_reopen_can_attach(BlockDriverState *parent, BdrvChild *child, BlockDriverState *new_child, Error **errp) { AioContext *parent_ctx = bdrv_get_aio_context(parent); AioContext *child_ctx = bdrv_get_aio_context(new_child); GSList *ignore; bool ret; ignore = g_slist_prepend(NULL, child); ret = bdrv_can_set_aio_context(new_child, parent_ctx, &ignore, NULL); g_slist_free(ignore); if (ret) { return ret; } ignore = g_slist_prepend(NULL, child); ret = bdrv_can_set_aio_context(parent, child_ctx, &ignore, errp); g_slist_free(ignore); return ret; } /* * Take a BDRVReopenState and check if the value of 'backing' in the * reopen_state->options QDict is valid or not. * * If 'backing' is missing from the QDict then return 0. * * If 'backing' contains the node name of the backing file of * reopen_state->bs then return 0. * * If 'backing' contains a different node name (or is null) then check * whether the current backing file can be replaced with the new one. * If that's the case then reopen_state->replace_backing_bs is set to * true and reopen_state->new_backing_bs contains a pointer to the new * backing BlockDriverState (or NULL). * * Return 0 on success, otherwise return < 0 and set @errp. */ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, Error **errp) { BlockDriverState *bs = reopen_state->bs; BlockDriverState *overlay_bs, *below_bs, *new_backing_bs; QObject *value; const char *str; value = qdict_get(reopen_state->options, "backing"); if (value == NULL) { return 0; } switch (qobject_type(value)) { case QTYPE_QNULL: new_backing_bs = NULL; break; case QTYPE_QSTRING: str = qstring_get_str(qobject_to(QString, value)); new_backing_bs = bdrv_lookup_bs(NULL, str, errp); if (new_backing_bs == NULL) { return -EINVAL; } else if (bdrv_recurse_has_child(new_backing_bs, bs)) { error_setg(errp, "Making '%s' a backing file of '%s' " "would create a cycle", str, bs->node_name); return -EINVAL; } break; default: /* 'backing' does not allow any other data type */ g_assert_not_reached(); } /* * Check AioContext compatibility so that the bdrv_set_backing_hd() call in * bdrv_reopen_commit() won't fail. */ if (new_backing_bs) { if (!bdrv_reopen_can_attach(bs, bs->backing, new_backing_bs, errp)) { return -EINVAL; } } /* * Ensure that @bs can really handle backing files, because we are * about to give it one (or swap the existing one) */ if (bs->drv->is_filter) { /* Filters always have a file or a backing child */ if (!bs->backing) { error_setg(errp, "'%s' is a %s filter node that does not support a " "backing child", bs->node_name, bs->drv->format_name); return -EINVAL; } } else if (!bs->drv->supports_backing) { error_setg(errp, "Driver '%s' of node '%s' does not support backing " "files", bs->drv->format_name, bs->node_name); return -EINVAL; } /* * Find the "actual" backing file by skipping all links that point * to an implicit node, if any (e.g. a commit filter node). * We cannot use any of the bdrv_skip_*() functions here because * those return the first explicit node, while we are looking for * its overlay here. */ overlay_bs = bs; for (below_bs = bdrv_filter_or_cow_bs(overlay_bs); below_bs && below_bs->implicit; below_bs = bdrv_filter_or_cow_bs(overlay_bs)) { overlay_bs = below_bs; } /* If we want to replace the backing file we need some extra checks */ if (new_backing_bs != bdrv_filter_or_cow_bs(overlay_bs)) { /* Check for implicit nodes between bs and its backing file */ if (bs != overlay_bs) { error_setg(errp, "Cannot change backing link if '%s' has " "an implicit backing file", bs->node_name); return -EPERM; } /* * Check if the backing link that we want to replace is frozen. * Note that * bdrv_filter_or_cow_child(overlay_bs) == overlay_bs->backing, * because we know that overlay_bs == bs, and that @bs * either is a filter that uses ->backing or a COW format BDS * with bs->drv->supports_backing == true. */ if (bdrv_is_backing_chain_frozen(overlay_bs, child_bs(overlay_bs->backing), errp)) { return -EPERM; } reopen_state->replace_backing_bs = true; if (new_backing_bs) { bdrv_ref(new_backing_bs); reopen_state->new_backing_bs = new_backing_bs; } } return 0; } /* * Prepares a BlockDriverState for reopen. All changes are staged in the * 'opaque' field of the BDRVReopenState, which is used and allocated by * the block driver layer .bdrv_reopen_prepare() * * bs is the BlockDriverState to reopen * flags are the new open flags * queue is the reopen queue * * Returns 0 on success, non-zero on error. On error errp will be set * as well. * * On failure, bdrv_reopen_abort() will be called to clean up any data. * It is the responsibility of the caller to then call the abort() or * commit() for any other BDS that have been left in a prepare() state * */ static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, Error **errp) { int ret = -1; int old_flags; Error *local_err = NULL; BlockDriver *drv; QemuOpts *opts; QDict *orig_reopen_opts; char *discard = NULL; bool read_only; bool drv_prepared = false; assert(reopen_state != NULL); assert(reopen_state->bs->drv != NULL); drv = reopen_state->bs->drv; /* This function and each driver's bdrv_reopen_prepare() remove * entries from reopen_state->options as they are processed, so * we need to make a copy of the original QDict. */ orig_reopen_opts = qdict_clone_shallow(reopen_state->options); /* Process generic block layer options */ opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) { ret = -EINVAL; goto error; } /* This was already called in bdrv_reopen_queue_child() so the flags * are up-to-date. This time we simply want to remove the options from * QemuOpts in order to indicate that they have been processed. */ old_flags = reopen_state->flags; update_flags_from_options(&reopen_state->flags, opts); assert(old_flags == reopen_state->flags); discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD); if (discard != NULL) { if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) { error_setg(errp, "Invalid discard option"); ret = -EINVAL; goto error; } } reopen_state->detect_zeroes = bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err); if (local_err) { error_propagate(errp, local_err); ret = -EINVAL; goto error; } /* All other options (including node-name and driver) must be unchanged. * Put them back into the QDict, so that they are checked at the end * of this function. */ qemu_opts_to_qdict(opts, reopen_state->options); /* If we are to stay read-only, do not allow permission change * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is * not set, or if the BDS still has copy_on_read enabled */ read_only = !(reopen_state->flags & BDRV_O_RDWR); ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err); if (local_err) { error_propagate(errp, local_err); goto error; } /* Calculate required permissions after reopening */ bdrv_reopen_perm(queue, reopen_state->bs, &reopen_state->perm, &reopen_state->shared_perm); ret = bdrv_flush(reopen_state->bs); if (ret) { error_setg_errno(errp, -ret, "Error flushing drive"); goto error; } if (drv->bdrv_reopen_prepare) { /* * If a driver-specific option is missing, it means that we * should reset it to its default value. * But not all options allow that, so we need to check it first. */ ret = bdrv_reset_options_allowed(reopen_state->bs, reopen_state->options, errp); if (ret) { goto error; } ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err); if (ret) { if (local_err != NULL) { error_propagate(errp, local_err); } else { bdrv_refresh_filename(reopen_state->bs); error_setg(errp, "failed while preparing to reopen image '%s'", reopen_state->bs->filename); } goto error; } } else { /* It is currently mandatory to have a bdrv_reopen_prepare() * handler for each supported drv. */ error_setg(errp, "Block format '%s' used by node '%s' " "does not support reopening files", drv->format_name, bdrv_get_device_or_node_name(reopen_state->bs)); ret = -1; goto error; } drv_prepared = true; /* * We must provide the 'backing' option if the BDS has a backing * file or if the image file has a backing file name as part of * its metadata. Otherwise the 'backing' option can be omitted. */ if (drv->supports_backing && reopen_state->backing_missing && (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) { error_setg(errp, "backing is missing for '%s'", reopen_state->bs->node_name); ret = -EINVAL; goto error; } /* * Allow changing the 'backing' option. The new value can be * either a reference to an existing node (using its node name) * or NULL to simply detach the current backing file. */ ret = bdrv_reopen_parse_backing(reopen_state, errp); if (ret < 0) { goto error; } qdict_del(reopen_state->options, "backing"); /* Options that are not handled are only okay if they are unchanged * compared to the old state. It is expected that some options are only * used for the initial open, but not reopen (e.g. filename) */ if (qdict_size(reopen_state->options)) { const QDictEntry *entry = qdict_first(reopen_state->options); do { QObject *new = entry->value; QObject *old = qdict_get(reopen_state->bs->options, entry->key); /* Allow child references (child_name=node_name) as long as they * point to the current child (i.e. everything stays the same). */ if (qobject_type(new) == QTYPE_QSTRING) { BdrvChild *child; QLIST_FOREACH(child, &reopen_state->bs->children, next) { if (!strcmp(child->name, entry->key)) { break; } } if (child) { if (!strcmp(child->bs->node_name, qstring_get_str(qobject_to(QString, new)))) { continue; /* Found child with this name, skip option */ } } } /* * TODO: When using -drive to specify blockdev options, all values * will be strings; however, when using -blockdev, blockdev-add or * filenames using the json:{} pseudo-protocol, they will be * correctly typed. * In contrast, reopening options are (currently) always strings * (because you can only specify them through qemu-io; all other * callers do not specify any options). * Therefore, when using anything other than -drive to create a BDS, * this cannot detect non-string options as unchanged, because * qobject_is_equal() always returns false for objects of different * type. In the future, this should be remedied by correctly typing * all options. For now, this is not too big of an issue because * the user can simply omit options which cannot be changed anyway, * so they will stay unchanged. */ if (!qobject_is_equal(new, old)) { error_setg(errp, "Cannot change the option '%s'", entry->key); ret = -EINVAL; goto error; } } while ((entry = qdict_next(reopen_state->options, entry))); } ret = 0; /* Restore the original reopen_state->options QDict */ qobject_unref(reopen_state->options); reopen_state->options = qobject_ref(orig_reopen_opts); error: if (ret < 0 && drv_prepared) { /* drv->bdrv_reopen_prepare() has succeeded, so we need to * call drv->bdrv_reopen_abort() before signaling an error * (bdrv_reopen_multiple() will not call bdrv_reopen_abort() * when the respective bdrv_reopen_prepare() has failed) */ if (drv->bdrv_reopen_abort) { drv->bdrv_reopen_abort(reopen_state); } } qemu_opts_del(opts); qobject_unref(orig_reopen_opts); g_free(discard); return ret; } /* * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and * makes them final by swapping the staging BlockDriverState contents into * the active BlockDriverState contents. */ static void bdrv_reopen_commit(BDRVReopenState *reopen_state) { BlockDriver *drv; BlockDriverState *bs; BdrvChild *child; assert(reopen_state != NULL); bs = reopen_state->bs; drv = bs->drv; assert(drv != NULL); /* If there are any driver level actions to take */ if (drv->bdrv_reopen_commit) { drv->bdrv_reopen_commit(reopen_state); } /* set BDS specific flags now */ qobject_unref(bs->explicit_options); qobject_unref(bs->options); bs->explicit_options = reopen_state->explicit_options; bs->options = reopen_state->options; bs->open_flags = reopen_state->flags; bs->read_only = !(reopen_state->flags & BDRV_O_RDWR); bs->detect_zeroes = reopen_state->detect_zeroes; if (reopen_state->replace_backing_bs) { qdict_del(bs->explicit_options, "backing"); qdict_del(bs->options, "backing"); } /* Remove child references from bs->options and bs->explicit_options. * Child options were already removed in bdrv_reopen_queue_child() */ QLIST_FOREACH(child, &bs->children, next) { qdict_del(bs->explicit_options, child->name); qdict_del(bs->options, child->name); } /* * Change the backing file if a new one was specified. We do this * after updating bs->options, so bdrv_refresh_filename() (called * from bdrv_set_backing_hd()) has the new values. */ if (reopen_state->replace_backing_bs) { BlockDriverState *old_backing_bs = child_bs(bs->backing); assert(!old_backing_bs || !old_backing_bs->implicit); /* Abort the permission update on the backing bs we're detaching */ if (old_backing_bs) { bdrv_abort_perm_update(old_backing_bs); } bdrv_set_backing_hd(bs, reopen_state->new_backing_bs, &error_abort); } bdrv_refresh_limits(bs, NULL); } /* * Abort the reopen, and delete and free the staged changes in * reopen_state */ static void bdrv_reopen_abort(BDRVReopenState *reopen_state) { BlockDriver *drv; assert(reopen_state != NULL); drv = reopen_state->bs->drv; assert(drv != NULL); if (drv->bdrv_reopen_abort) { drv->bdrv_reopen_abort(reopen_state); } } static void bdrv_close(BlockDriverState *bs) { BdrvAioNotifier *ban, *ban_next; BdrvChild *child, *next; assert(!bs->refcnt); bdrv_drained_begin(bs); /* complete I/O */ bdrv_flush(bs); bdrv_drain(bs); /* in case flush left pending I/O */ if (bs->drv) { if (bs->drv->bdrv_close) { /* Must unfreeze all children, so bdrv_unref_child() works */ bs->drv->bdrv_close(bs); } bs->drv = NULL; } QLIST_FOREACH_SAFE(child, &bs->children, next, next) { bdrv_unref_child(bs, child); } bs->backing = NULL; bs->file = NULL; g_free(bs->opaque); bs->opaque = NULL; qatomic_set(&bs->copy_on_read, 0); bs->backing_file[0] = '\0'; bs->backing_format[0] = '\0'; bs->total_sectors = 0; bs->encrypted = false; bs->sg = false; qobject_unref(bs->options); qobject_unref(bs->explicit_options); bs->options = NULL; bs->explicit_options = NULL; qobject_unref(bs->full_open_options); bs->full_open_options = NULL; bdrv_release_named_dirty_bitmaps(bs); assert(QLIST_EMPTY(&bs->dirty_bitmaps)); QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { g_free(ban); } QLIST_INIT(&bs->aio_notifiers); bdrv_drained_end(bs); /* * If we're still inside some bdrv_drain_all_begin()/end() sections, end * them now since this BDS won't exist anymore when bdrv_drain_all_end() * gets called. */ if (bs->quiesce_counter) { bdrv_drain_all_end_quiesce(bs); } } void bdrv_close_all(void) { assert(job_next(NULL) == NULL); /* Drop references from requests still in flight, such as canceled block * jobs whose AIO context has not been polled yet */ bdrv_drain_all(); blk_remove_all_bs(); blockdev_close_all_bdrv_states(); assert(QTAILQ_EMPTY(&all_bdrv_states)); } static bool should_update_child(BdrvChild *c, BlockDriverState *to) { GQueue *queue; GHashTable *found; bool ret; if (c->klass->stay_at_node) { return false; } /* If the child @c belongs to the BDS @to, replacing the current * c->bs by @to would mean to create a loop. * * Such a case occurs when appending a BDS to a backing chain. * For instance, imagine the following chain: * * guest device -> node A -> further backing chain... * * Now we create a new BDS B which we want to put on top of this * chain, so we first attach A as its backing node: * * node B * | * v * guest device -> node A -> further backing chain... * * Finally we want to replace A by B. When doing that, we want to * replace all pointers to A by pointers to B -- except for the * pointer from B because (1) that would create a loop, and (2) * that pointer should simply stay intact: * * guest device -> node B * | * v * node A -> further backing chain... * * In general, when replacing a node A (c->bs) by a node B (@to), * if A is a child of B, that means we cannot replace A by B there * because that would create a loop. Silently detaching A from B * is also not really an option. So overall just leaving A in * place there is the most sensible choice. * * We would also create a loop in any cases where @c is only * indirectly referenced by @to. Prevent this by returning false * if @c is found (by breadth-first search) anywhere in the whole * subtree of @to. */ ret = true; found = g_hash_table_new(NULL, NULL); g_hash_table_add(found, to); queue = g_queue_new(); g_queue_push_tail(queue, to); while (!g_queue_is_empty(queue)) { BlockDriverState *v = g_queue_pop_head(queue); BdrvChild *c2; QLIST_FOREACH(c2, &v->children, next) { if (c2 == c) { ret = false; break; } if (g_hash_table_contains(found, c2->bs)) { continue; } g_queue_push_tail(queue, c2->bs); g_hash_table_add(found, c2->bs); } } g_queue_free(queue); g_hash_table_destroy(found); return ret; } typedef struct BdrvRemoveFilterOrCowChild { BdrvChild *child; bool is_backing; } BdrvRemoveFilterOrCowChild; static void bdrv_remove_filter_or_cow_child_abort(void *opaque) { BdrvRemoveFilterOrCowChild *s = opaque; BlockDriverState *parent_bs = s->child->opaque; QLIST_INSERT_HEAD(&parent_bs->children, s->child, next); if (s->is_backing) { parent_bs->backing = s->child; } else { parent_bs->file = s->child; } /* * We don't have to restore child->bs here to undo bdrv_replace_child() * because that function is transactionable and it registered own completion * entries in @tran, so .abort() for bdrv_replace_child_safe() will be * called automatically. */ } static void bdrv_remove_filter_or_cow_child_commit(void *opaque) { BdrvRemoveFilterOrCowChild *s = opaque; bdrv_child_free(s->child); } static TransactionActionDrv bdrv_remove_filter_or_cow_child_drv = { .abort = bdrv_remove_filter_or_cow_child_abort, .commit = bdrv_remove_filter_or_cow_child_commit, .clean = g_free, }; /* * A function to remove backing-chain child of @bs if exists: cow child for * format nodes (always .backing) and filter child for filters (may be .file or * .backing) */ __attribute__((unused)) static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs, Transaction *tran) { BdrvRemoveFilterOrCowChild *s; BdrvChild *child = bdrv_filter_or_cow_child(bs); if (!child) { return; } if (child->bs) { bdrv_replace_child_safe(child, NULL, tran); } s = g_new(BdrvRemoveFilterOrCowChild, 1); *s = (BdrvRemoveFilterOrCowChild) { .child = child, .is_backing = (child == bs->backing), }; tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s); QLIST_SAFE_REMOVE(child, next); if (s->is_backing) { bs->backing = NULL; } else { bs->file = NULL; } } static int bdrv_replace_node_noperm(BlockDriverState *from, BlockDriverState *to, bool auto_skip, Transaction *tran, Error **errp) { BdrvChild *c, *next; QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) { assert(c->bs == from); if (!should_update_child(c, to)) { if (auto_skip) { continue; } error_setg(errp, "Should not change '%s' link to '%s'", c->name, from->node_name); return -EINVAL; } if (c->frozen) { error_setg(errp, "Cannot change '%s' link to '%s'", c->name, from->node_name); return -EPERM; } bdrv_replace_child_safe(c, to, tran); } return 0; } /* * With auto_skip=true bdrv_replace_node_common skips updating from parents * if it creates a parent-child relation loop or if parent is block-job. * * With auto_skip=false the error is returned if from has a parent which should * not be updated. */ static int bdrv_replace_node_common(BlockDriverState *from, BlockDriverState *to, bool auto_skip, Error **errp) { Transaction *tran = tran_new(); g_autoptr(GHashTable) found = NULL; g_autoptr(GSList) refresh_list = NULL; int ret; /* Make sure that @from doesn't go away until we have successfully attached * all of its parents to @to. */ bdrv_ref(from); assert(qemu_get_current_aio_context() == qemu_get_aio_context()); assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to)); bdrv_drained_begin(from); /* * Do the replacement without permission update. * Replacement may influence the permissions, we should calculate new * permissions based on new graph. If we fail, we'll roll-back the * replacement. */ ret = bdrv_replace_node_noperm(from, to, auto_skip, tran, errp); if (ret < 0) { goto out; } found = g_hash_table_new(NULL, NULL); refresh_list = bdrv_topological_dfs(refresh_list, found, to); refresh_list = bdrv_topological_dfs(refresh_list, found, from); ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp); if (ret < 0) { goto out; } ret = 0; out: tran_finalize(tran, ret); bdrv_drained_end(from); bdrv_unref(from); return ret; } int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, Error **errp) { return bdrv_replace_node_common(from, to, true, errp); } /* * Add new bs contents at the top of an image chain while the chain is * live, while keeping required fields on the top layer. * * This will modify the BlockDriverState fields, and swap contents * between bs_new and bs_top. Both bs_new and bs_top are modified. * * bs_new must not be attached to a BlockBackend and must not have backing * child. * * This function does not create any image files. */ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, Error **errp) { int ret; Transaction *tran = tran_new(); assert(!bs_new->backing); ret = bdrv_attach_child_noperm(bs_new, bs_top, "backing", &child_of_bds, bdrv_backing_role(bs_new), &bs_new->backing, tran, errp); if (ret < 0) { goto out; } ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp); if (ret < 0) { goto out; } ret = bdrv_refresh_perms(bs_new, errp); out: tran_finalize(tran, ret); bdrv_refresh_limits(bs_top, NULL); return ret; } static void bdrv_delete(BlockDriverState *bs) { assert(bdrv_op_blocker_is_empty(bs)); assert(!bs->refcnt); /* remove from list, if necessary */ if (bs->node_name[0] != '\0') { QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list); } QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list); bdrv_close(bs); g_free(bs); } BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *node_options, int flags, Error **errp) { BlockDriverState *new_node_bs; Error *local_err = NULL; new_node_bs = bdrv_open(NULL, NULL, node_options, flags, errp); if (new_node_bs == NULL) { error_prepend(errp, "Could not create node: "); return NULL; } bdrv_drained_begin(bs); bdrv_replace_node(bs, new_node_bs, &local_err); bdrv_drained_end(bs); if (local_err) { bdrv_unref(new_node_bs); error_propagate(errp, local_err); return NULL; } return new_node_bs; } /* * Run consistency checks on an image * * Returns 0 if the check could be completed (it doesn't mean that the image is * free of errors) or -errno when an internal error occurred. The results of the * check are stored in res. */ int coroutine_fn bdrv_co_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix) { if (bs->drv == NULL) { return -ENOMEDIUM; } if (bs->drv->bdrv_co_check == NULL) { return -ENOTSUP; } memset(res, 0, sizeof(*res)); return bs->drv->bdrv_co_check(bs, res, fix); } /* * Return values: * 0 - success * -EINVAL - backing format specified, but no file * -ENOSPC - can't update the backing file because no space is left in the * image file header * -ENOTSUP - format driver doesn't support changing the backing file */ int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file, const char *backing_fmt, bool warn) { BlockDriver *drv = bs->drv; int ret; if (!drv) { return -ENOMEDIUM; } /* Backing file format doesn't make sense without a backing file */ if (backing_fmt && !backing_file) { return -EINVAL; } if (warn && backing_file && !backing_fmt) { warn_report("Deprecated use of backing file without explicit " "backing format, use of this image requires " "potentially unsafe format probing"); } if (drv->bdrv_change_backing_file != NULL) { ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt); } else { ret = -ENOTSUP; } if (ret == 0) { pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: ""); pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: ""); pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), backing_file ?: ""); } return ret; } /* * Finds the first non-filter node above bs in the chain between * active and bs. The returned node is either an immediate parent of * bs, or there are only filter nodes between the two. * * Returns NULL if bs is not found in active's image chain, * or if active == bs. * * Returns the bottommost base image if bs == NULL. */ BlockDriverState *bdrv_find_overlay(BlockDriverState *active, BlockDriverState *bs) { bs = bdrv_skip_filters(bs); active = bdrv_skip_filters(active); while (active) { BlockDriverState *next = bdrv_backing_chain_next(active); if (bs == next) { return active; } active = next; } return NULL; } /* Given a BDS, searches for the base layer. */ BlockDriverState *bdrv_find_base(BlockDriverState *bs) { return bdrv_find_overlay(bs, NULL); } /* * Return true if at least one of the COW (backing) and filter links * between @bs and @base is frozen. @errp is set if that's the case. * @base must be reachable from @bs, or NULL. */ bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base, Error **errp) { BlockDriverState *i; BdrvChild *child; for (i = bs; i != base; i = child_bs(child)) { child = bdrv_filter_or_cow_child(i); if (child && child->frozen) { error_setg(errp, "Cannot change '%s' link from '%s' to '%s'", child->name, i->node_name, child->bs->node_name); return true; } } return false; } /* * Freeze all COW (backing) and filter links between @bs and @base. * If any of the links is already frozen the operation is aborted and * none of the links are modified. * @base must be reachable from @bs, or NULL. * Returns 0 on success. On failure returns < 0 and sets @errp. */ int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base, Error **errp) { BlockDriverState *i; BdrvChild *child; if (bdrv_is_backing_chain_frozen(bs, base, errp)) { return -EPERM; } for (i = bs; i != base; i = child_bs(child)) { child = bdrv_filter_or_cow_child(i); if (child && child->bs->never_freeze) { error_setg(errp, "Cannot freeze '%s' link to '%s'", child->name, child->bs->node_name); return -EPERM; } } for (i = bs; i != base; i = child_bs(child)) { child = bdrv_filter_or_cow_child(i); if (child) { child->frozen = true; } } return 0; } /* * Unfreeze all COW (backing) and filter links between @bs and @base. * The caller must ensure that all links are frozen before using this * function. * @base must be reachable from @bs, or NULL. */ void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base) { BlockDriverState *i; BdrvChild *child; for (i = bs; i != base; i = child_bs(child)) { child = bdrv_filter_or_cow_child(i); if (child) { assert(child->frozen); child->frozen = false; } } } /* * Drops images above 'base' up to and including 'top', and sets the image * above 'top' to have base as its backing file. * * Requires that the overlay to 'top' is opened r/w, so that the backing file * information in 'bs' can be properly updated. * * E.g., this will convert the following chain: * bottom <- base <- intermediate <- top <- active * * to * * bottom <- base <- active * * It is allowed for bottom==base, in which case it converts: * * base <- intermediate <- top <- active * * to * * base <- active * * If backing_file_str is non-NULL, it will be used when modifying top's * overlay image metadata. * * Error conditions: * if active == top, that is considered an error * */ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, const char *backing_file_str) { BlockDriverState *explicit_top = top; bool update_inherits_from; BdrvChild *c; Error *local_err = NULL; int ret = -EIO; g_autoptr(GSList) updated_children = NULL; GSList *p; bdrv_ref(top); bdrv_subtree_drained_begin(top); if (!top->drv || !base->drv) { goto exit; } /* Make sure that base is in the backing chain of top */ if (!bdrv_chain_contains(top, base)) { goto exit; } /* If 'base' recursively inherits from 'top' then we should set * base->inherits_from to top->inherits_from after 'top' and all * other intermediate nodes have been dropped. * If 'top' is an implicit node (e.g. "commit_top") we should skip * it because no one inherits from it. We use explicit_top for that. */ explicit_top = bdrv_skip_implicit_filters(explicit_top); update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top); /* success - we can delete the intermediate states, and link top->base */ /* TODO Check graph modification op blockers (BLK_PERM_GRAPH_MOD) once * we've figured out how they should work. */ if (!backing_file_str) { bdrv_refresh_filename(base); backing_file_str = base->filename; } QLIST_FOREACH(c, &top->parents, next_parent) { updated_children = g_slist_prepend(updated_children, c); } bdrv_replace_node_common(top, base, false, &local_err); if (local_err) { error_report_err(local_err); goto exit; } for (p = updated_children; p; p = p->next) { c = p->data; if (c->klass->update_filename) { ret = c->klass->update_filename(c, base, backing_file_str, &local_err); if (ret < 0) { /* * TODO: Actually, we want to rollback all previous iterations * of this loop, and (which is almost impossible) previous * bdrv_replace_node()... * * Note, that c->klass->update_filename may lead to permission * update, so it's a bad idea to call it inside permission * update transaction of bdrv_replace_node. */ error_report_err(local_err); goto exit; } } } if (update_inherits_from) { base->inherits_from = explicit_top->inherits_from; } ret = 0; exit: bdrv_subtree_drained_end(top); bdrv_unref(top); return ret; } /** * Implementation of BlockDriver.bdrv_get_allocated_file_size() that * sums the size of all data-bearing children. (This excludes backing * children.) */ static int64_t bdrv_sum_allocated_file_size(BlockDriverState *bs) { BdrvChild *child; int64_t child_size, sum = 0; QLIST_FOREACH(child, &bs->children, next) { if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED)) { child_size = bdrv_get_allocated_file_size(child->bs); if (child_size < 0) { return child_size; } sum += child_size; } } return sum; } /** * Length of a allocated file in bytes. Sparse files are counted by actual * allocated space. Return < 0 if error or unknown. */ int64_t bdrv_get_allocated_file_size(BlockDriverState *bs) { BlockDriver *drv = bs->drv; if (!drv) { return -ENOMEDIUM; } if (drv->bdrv_get_allocated_file_size) { return drv->bdrv_get_allocated_file_size(bs); } if (drv->bdrv_file_open) { /* * Protocol drivers default to -ENOTSUP (most of their data is * not stored in any of their children (if they even have any), * so there is no generic way to figure it out). */ return -ENOTSUP; } else if (drv->is_filter) { /* Filter drivers default to the size of their filtered child */ return bdrv_get_allocated_file_size(bdrv_filter_bs(bs)); } else { /* Other drivers default to summing their children's sizes */ return bdrv_sum_allocated_file_size(bs); } } /* * bdrv_measure: * @drv: Format driver * @opts: Creation options for new image * @in_bs: Existing image containing data for new image (may be NULL) * @errp: Error object * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo()) * or NULL on error * * Calculate file size required to create a new image. * * If @in_bs is given then space for allocated clusters and zero clusters * from that image are included in the calculation. If @opts contains a * backing file that is shared by @in_bs then backing clusters may be omitted * from the calculation. * * If @in_bs is NULL then the calculation includes no allocated clusters * unless a preallocation option is given in @opts. * * Note that @in_bs may use a different BlockDriver from @drv. * * If an error occurs the @errp pointer is set. */ BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, BlockDriverState *in_bs, Error **errp) { if (!drv->bdrv_measure) { error_setg(errp, "Block driver '%s' does not support size measurement", drv->format_name); return NULL; } return drv->bdrv_measure(opts, in_bs, errp); } /** * Return number of sectors on success, -errno on error. */ int64_t bdrv_nb_sectors(BlockDriverState *bs) { BlockDriver *drv = bs->drv; if (!drv) return -ENOMEDIUM; if (drv->has_variable_length) { int ret = refresh_total_sectors(bs, bs->total_sectors); if (ret < 0) { return ret; } } return bs->total_sectors; } /** * Return length in bytes on success, -errno on error. * The length is always a multiple of BDRV_SECTOR_SIZE. */ int64_t bdrv_getlength(BlockDriverState *bs) { int64_t ret = bdrv_nb_sectors(bs); if (ret < 0) { return ret; } if (ret > INT64_MAX / BDRV_SECTOR_SIZE) { return -EFBIG; } return ret * BDRV_SECTOR_SIZE; } /* return 0 as number of sectors if no device present or error */ void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr) { int64_t nb_sectors = bdrv_nb_sectors(bs); *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors; } bool bdrv_is_sg(BlockDriverState *bs) { return bs->sg; } /** * Return whether the given node supports compressed writes. */ bool bdrv_supports_compressed_writes(BlockDriverState *bs) { BlockDriverState *filtered; if (!bs->drv || !block_driver_can_compress(bs->drv)) { return false; } filtered = bdrv_filter_bs(bs); if (filtered) { /* * Filters can only forward compressed writes, so we have to * check the child. */ return bdrv_supports_compressed_writes(filtered); } return true; } const char *bdrv_get_format_name(BlockDriverState *bs) { return bs->drv ? bs->drv->format_name : NULL; } static int qsort_strcmp(const void *a, const void *b) { return strcmp(*(char *const *)a, *(char *const *)b); } void bdrv_iterate_format(void (*it)(void *opaque, const char *name), void *opaque, bool read_only) { BlockDriver *drv; int count = 0; int i; const char **formats = NULL; QLIST_FOREACH(drv, &bdrv_drivers, list) { if (drv->format_name) { bool found = false; int i = count; if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) { continue; } while (formats && i && !found) { found = !strcmp(formats[--i], drv->format_name); } if (!found) { formats = g_renew(const char *, formats, count + 1); formats[count++] = drv->format_name; } } } for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) { const char *format_name = block_driver_modules[i].format_name; if (format_name) { bool found = false; int j = count; if (use_bdrv_whitelist && !bdrv_format_is_whitelisted(format_name, read_only)) { continue; } while (formats && j && !found) { found = !strcmp(formats[--j], format_name); } if (!found) { formats = g_renew(const char *, formats, count + 1); formats[count++] = format_name; } } } qsort(formats, count, sizeof(formats[0]), qsort_strcmp); for (i = 0; i < count; i++) { it(opaque, formats[i]); } g_free(formats); } /* This function is to find a node in the bs graph */ BlockDriverState *bdrv_find_node(const char *node_name) { BlockDriverState *bs; assert(node_name); QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { if (!strcmp(node_name, bs->node_name)) { return bs; } } return NULL; } /* Put this QMP function here so it can access the static graph_bdrv_states. */ BlockDeviceInfoList *bdrv_named_nodes_list(bool flat, Error **errp) { BlockDeviceInfoList *list; BlockDriverState *bs; list = NULL; QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp); if (!info) { qapi_free_BlockDeviceInfoList(list); return NULL; } QAPI_LIST_PREPEND(list, info); } return list; } typedef struct XDbgBlockGraphConstructor { XDbgBlockGraph *graph; GHashTable *graph_nodes; } XDbgBlockGraphConstructor; static XDbgBlockGraphConstructor *xdbg_graph_new(void) { XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1); gr->graph = g_new0(XDbgBlockGraph, 1); gr->graph_nodes = g_hash_table_new(NULL, NULL); return gr; } static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr) { XDbgBlockGraph *graph = gr->graph; g_hash_table_destroy(gr->graph_nodes); g_free(gr); return graph; } static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node) { uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node); if (ret != 0) { return ret; } /* * Start counting from 1, not 0, because 0 interferes with not-found (NULL) * answer of g_hash_table_lookup. */ ret = g_hash_table_size(gr->graph_nodes) + 1; g_hash_table_insert(gr->graph_nodes, node, (void *)ret); return ret; } static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node, XDbgBlockGraphNodeType type, const char *name) { XDbgBlockGraphNode *n; n = g_new0(XDbgBlockGraphNode, 1); n->id = xdbg_graph_node_num(gr, node); n->type = type; n->name = g_strdup(name); QAPI_LIST_PREPEND(gr->graph->nodes, n); } static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent, const BdrvChild *child) { BlockPermission qapi_perm; XDbgBlockGraphEdge *edge; edge = g_new0(XDbgBlockGraphEdge, 1); edge->parent = xdbg_graph_node_num(gr, parent); edge->child = xdbg_graph_node_num(gr, child->bs); edge->name = g_strdup(child->name); for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) { uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm); if (flag & child->perm) { QAPI_LIST_PREPEND(edge->perm, qapi_perm); } if (flag & child->shared_perm) { QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm); } } QAPI_LIST_PREPEND(gr->graph->edges, edge); } XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp) { BlockBackend *blk; BlockJob *job; BlockDriverState *bs; BdrvChild *child; XDbgBlockGraphConstructor *gr = xdbg_graph_new(); for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) { char *allocated_name = NULL; const char *name = blk_name(blk); if (!*name) { name = allocated_name = blk_get_attached_dev_id(blk); } xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND, name); g_free(allocated_name); if (blk_root(blk)) { xdbg_graph_add_edge(gr, blk, blk_root(blk)); } } for (job = block_job_next(NULL); job; job = block_job_next(job)) { GSList *el; xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB, job->job.id); for (el = job->nodes; el; el = el->next) { xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data); } } QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER, bs->node_name); QLIST_FOREACH(child, &bs->children, next) { xdbg_graph_add_edge(gr, bs, child); } } return xdbg_graph_finalize(gr); } BlockDriverState *bdrv_lookup_bs(const char *device, const char *node_name, Error **errp) { BlockBackend *blk; BlockDriverState *bs; if (device) { blk = blk_by_name(device); if (blk) { bs = blk_bs(blk); if (!bs) { error_setg(errp, "Device '%s' has no medium", device); } return bs; } } if (node_name) { bs = bdrv_find_node(node_name); if (bs) { return bs; } } error_setg(errp, "Cannot find device=\'%s\' nor node-name=\'%s\'", device ? device : "", node_name ? node_name : ""); return NULL; } /* If 'base' is in the same chain as 'top', return true. Otherwise, * return false. If either argument is NULL, return false. */ bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base) { while (top && top != base) { top = bdrv_filter_or_cow_bs(top); } return top != NULL; } BlockDriverState *bdrv_next_node(BlockDriverState *bs) { if (!bs) { return QTAILQ_FIRST(&graph_bdrv_states); } return QTAILQ_NEXT(bs, node_list); } BlockDriverState *bdrv_next_all_states(BlockDriverState *bs) { if (!bs) { return QTAILQ_FIRST(&all_bdrv_states); } return QTAILQ_NEXT(bs, bs_list); } const char *bdrv_get_node_name(const BlockDriverState *bs) { return bs->node_name; } const char *bdrv_get_parent_name(const BlockDriverState *bs) { BdrvChild *c; const char *name; /* If multiple parents have a name, just pick the first one. */ QLIST_FOREACH(c, &bs->parents, next_parent) { if (c->klass->get_name) { name = c->klass->get_name(c); if (name && *name) { return name; } } } return NULL; } /* TODO check what callers really want: bs->node_name or blk_name() */ const char *bdrv_get_device_name(const BlockDriverState *bs) { return bdrv_get_parent_name(bs) ?: ""; } /* This can be used to identify nodes that might not have a device * name associated. Since node and device names live in the same * namespace, the result is unambiguous. The exception is if both are * absent, then this returns an empty (non-null) string. */ const char *bdrv_get_device_or_node_name(const BlockDriverState *bs) { return bdrv_get_parent_name(bs) ?: bs->node_name; } int bdrv_get_flags(BlockDriverState *bs) { return bs->open_flags; } int bdrv_has_zero_init_1(BlockDriverState *bs) { return 1; } int bdrv_has_zero_init(BlockDriverState *bs) { BlockDriverState *filtered; if (!bs->drv) { return 0; } /* If BS is a copy on write image, it is initialized to the contents of the base image, which may not be zeroes. */ if (bdrv_cow_child(bs)) { return 0; } if (bs->drv->bdrv_has_zero_init) { return bs->drv->bdrv_has_zero_init(bs); } filtered = bdrv_filter_bs(bs); if (filtered) { return bdrv_has_zero_init(filtered); } /* safe default */ return 0; } bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs) { if (!(bs->open_flags & BDRV_O_UNMAP)) { return false; } return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP; } void bdrv_get_backing_filename(BlockDriverState *bs, char *filename, int filename_size) { pstrcpy(filename, filename_size, bs->backing_file); } int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) { int ret; BlockDriver *drv = bs->drv; /* if bs->drv == NULL, bs is closed, so there's nothing to do here */ if (!drv) { return -ENOMEDIUM; } if (!drv->bdrv_get_info) { BlockDriverState *filtered = bdrv_filter_bs(bs); if (filtered) { return bdrv_get_info(filtered, bdi); } return -ENOTSUP; } memset(bdi, 0, sizeof(*bdi)); ret = drv->bdrv_get_info(bs, bdi); if (ret < 0) { return ret; } if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) { return -EINVAL; } return 0; } ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, Error **errp) { BlockDriver *drv = bs->drv; if (drv && drv->bdrv_get_specific_info) { return drv->bdrv_get_specific_info(bs, errp); } return NULL; } BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs) { BlockDriver *drv = bs->drv; if (!drv || !drv->bdrv_get_specific_stats) { return NULL; } return drv->bdrv_get_specific_stats(bs); } void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event) { if (!bs || !bs->drv || !bs->drv->bdrv_debug_event) { return; } bs->drv->bdrv_debug_event(bs, event); } static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs) { while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) { bs = bdrv_primary_bs(bs); } if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) { assert(bs->drv->bdrv_debug_remove_breakpoint); return bs; } return NULL; } int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event, const char *tag) { bs = bdrv_find_debug_node(bs); if (bs) { return bs->drv->bdrv_debug_breakpoint(bs, event, tag); } return -ENOTSUP; } int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag) { bs = bdrv_find_debug_node(bs); if (bs) { return bs->drv->bdrv_debug_remove_breakpoint(bs, tag); } return -ENOTSUP; } int bdrv_debug_resume(BlockDriverState *bs, const char *tag) { while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) { bs = bdrv_primary_bs(bs); } if (bs && bs->drv && bs->drv->bdrv_debug_resume) { return bs->drv->bdrv_debug_resume(bs, tag); } return -ENOTSUP; } bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag) { while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) { bs = bdrv_primary_bs(bs); } if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) { return bs->drv->bdrv_debug_is_suspended(bs, tag); } return false; } /* backing_file can either be relative, or absolute, or a protocol. If it is * relative, it must be relative to the chain. So, passing in bs->filename * from a BDS as backing_file should not be done, as that may be relative to * the CWD rather than the chain. */ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, const char *backing_file) { char *filename_full = NULL; char *backing_file_full = NULL; char *filename_tmp = NULL; int is_protocol = 0; bool filenames_refreshed = false; BlockDriverState *curr_bs = NULL; BlockDriverState *retval = NULL; BlockDriverState *bs_below; if (!bs || !bs->drv || !backing_file) { return NULL; } filename_full = g_malloc(PATH_MAX); backing_file_full = g_malloc(PATH_MAX); is_protocol = path_has_protocol(backing_file); /* * Being largely a legacy function, skip any filters here * (because filters do not have normal filenames, so they cannot * match anyway; and allowing json:{} filenames is a bit out of * scope). */ for (curr_bs = bdrv_skip_filters(bs); bdrv_cow_child(curr_bs) != NULL; curr_bs = bs_below) { bs_below = bdrv_backing_chain_next(curr_bs); if (bdrv_backing_overridden(curr_bs)) { /* * If the backing file was overridden, we can only compare * directly against the backing node's filename. */ if (!filenames_refreshed) { /* * This will automatically refresh all of the * filenames in the rest of the backing chain, so we * only need to do this once. */ bdrv_refresh_filename(bs_below); filenames_refreshed = true; } if (strcmp(backing_file, bs_below->filename) == 0) { retval = bs_below; break; } } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) { /* * If either of the filename paths is actually a protocol, then * compare unmodified paths; otherwise make paths relative. */ char *backing_file_full_ret; if (strcmp(backing_file, curr_bs->backing_file) == 0) { retval = bs_below; break; } /* Also check against the full backing filename for the image */ backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs, NULL); if (backing_file_full_ret) { bool equal = strcmp(backing_file, backing_file_full_ret) == 0; g_free(backing_file_full_ret); if (equal) { retval = bs_below; break; } } } else { /* If not an absolute filename path, make it relative to the current * image's filename path */ filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file, NULL); /* We are going to compare canonicalized absolute pathnames */ if (!filename_tmp || !realpath(filename_tmp, filename_full)) { g_free(filename_tmp); continue; } g_free(filename_tmp); /* We need to make sure the backing filename we are comparing against * is relative to the current image filename (or absolute) */ filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL); if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) { g_free(filename_tmp); continue; } g_free(filename_tmp); if (strcmp(backing_file_full, filename_full) == 0) { retval = bs_below; break; } } } g_free(filename_full); g_free(backing_file_full); return retval; } void bdrv_init(void) { module_call_init(MODULE_INIT_BLOCK); } void bdrv_init_with_whitelist(void) { use_bdrv_whitelist = 1; bdrv_init(); } int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp) { BdrvChild *child, *parent; Error *local_err = NULL; int ret; BdrvDirtyBitmap *bm; if (!bs->drv) { return -ENOMEDIUM; } QLIST_FOREACH(child, &bs->children, next) { bdrv_co_invalidate_cache(child->bs, &local_err); if (local_err) { error_propagate(errp, local_err); return -EINVAL; } } /* * Update permissions, they may differ for inactive nodes. * * Note that the required permissions of inactive images are always a * subset of the permissions required after activating the image. This * allows us to just get the permissions upfront without restricting * drv->bdrv_invalidate_cache(). * * It also means that in error cases, we don't have to try and revert to * the old permissions (which is an operation that could fail, too). We can * just keep the extended permissions for the next time that an activation * of the image is tried. */ if (bs->open_flags & BDRV_O_INACTIVE) { bs->open_flags &= ~BDRV_O_INACTIVE; ret = bdrv_refresh_perms(bs, errp); if (ret < 0) { bs->open_flags |= BDRV_O_INACTIVE; return ret; } if (bs->drv->bdrv_co_invalidate_cache) { bs->drv->bdrv_co_invalidate_cache(bs, &local_err); if (local_err) { bs->open_flags |= BDRV_O_INACTIVE; error_propagate(errp, local_err); return -EINVAL; } } FOR_EACH_DIRTY_BITMAP(bs, bm) { bdrv_dirty_bitmap_skip_store(bm, false); } ret = refresh_total_sectors(bs, bs->total_sectors); if (ret < 0) { bs->open_flags |= BDRV_O_INACTIVE; error_setg_errno(errp, -ret, "Could not refresh total sector count"); return ret; } } QLIST_FOREACH(parent, &bs->parents, next_parent) { if (parent->klass->activate) { parent->klass->activate(parent, &local_err); if (local_err) { bs->open_flags |= BDRV_O_INACTIVE; error_propagate(errp, local_err); return -EINVAL; } } } return 0; } void bdrv_invalidate_cache_all(Error **errp) { BlockDriverState *bs; BdrvNextIterator it; for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { AioContext *aio_context = bdrv_get_aio_context(bs); int ret; aio_context_acquire(aio_context); ret = bdrv_invalidate_cache(bs, errp); aio_context_release(aio_context); if (ret < 0) { bdrv_next_cleanup(&it); return; } } } static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active) { BdrvChild *parent; QLIST_FOREACH(parent, &bs->parents, next_parent) { if (parent->klass->parent_is_bds) { BlockDriverState *parent_bs = parent->opaque; if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) { return true; } } } return false; } static int bdrv_inactivate_recurse(BlockDriverState *bs) { BdrvChild *child, *parent; int ret; if (!bs->drv) { return -ENOMEDIUM; } /* Make sure that we don't inactivate a child before its parent. * It will be covered by recursion from the yet active parent. */ if (bdrv_has_bds_parent(bs, true)) { return 0; } assert(!(bs->open_flags & BDRV_O_INACTIVE)); /* Inactivate this node */ if (bs->drv->bdrv_inactivate) { ret = bs->drv->bdrv_inactivate(bs); if (ret < 0) { return ret; } } QLIST_FOREACH(parent, &bs->parents, next_parent) { if (parent->klass->inactivate) { ret = parent->klass->inactivate(parent); if (ret < 0) { return ret; } } } bs->open_flags |= BDRV_O_INACTIVE; /* * Update permissions, they may differ for inactive nodes. * We only tried to loosen restrictions, so errors are not fatal, ignore * them. */ bdrv_refresh_perms(bs, NULL); /* Recursively inactivate children */ QLIST_FOREACH(child, &bs->children, next) { ret = bdrv_inactivate_recurse(child->bs); if (ret < 0) { return ret; } } return 0; } int bdrv_inactivate_all(void) { BlockDriverState *bs = NULL; BdrvNextIterator it; int ret = 0; GSList *aio_ctxs = NULL, *ctx; for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { AioContext *aio_context = bdrv_get_aio_context(bs); if (!g_slist_find(aio_ctxs, aio_context)) { aio_ctxs = g_slist_prepend(aio_ctxs, aio_context); aio_context_acquire(aio_context); } } for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { /* Nodes with BDS parents are covered by recursion from the last * parent that gets inactivated. Don't inactivate them a second * time if that has already happened. */ if (bdrv_has_bds_parent(bs, false)) { continue; } ret = bdrv_inactivate_recurse(bs); if (ret < 0) { bdrv_next_cleanup(&it); goto out; } } out: for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) { AioContext *aio_context = ctx->data; aio_context_release(aio_context); } g_slist_free(aio_ctxs); return ret; } /**************************************************************/ /* removable device support */ /** * Return TRUE if the media is present */ bool bdrv_is_inserted(BlockDriverState *bs) { BlockDriver *drv = bs->drv; BdrvChild *child; if (!drv) { return false; } if (drv->bdrv_is_inserted) { return drv->bdrv_is_inserted(bs); } QLIST_FOREACH(child, &bs->children, next) { if (!bdrv_is_inserted(child->bs)) { return false; } } return true; } /** * If eject_flag is TRUE, eject the media. Otherwise, close the tray */ void bdrv_eject(BlockDriverState *bs, bool eject_flag) { BlockDriver *drv = bs->drv; if (drv && drv->bdrv_eject) { drv->bdrv_eject(bs, eject_flag); } } /** * Lock or unlock the media (if it is locked, the user won't be able * to eject it manually). */ void bdrv_lock_medium(BlockDriverState *bs, bool locked) { BlockDriver *drv = bs->drv; trace_bdrv_lock_medium(bs, locked); if (drv && drv->bdrv_lock_medium) { drv->bdrv_lock_medium(bs, locked); } } /* Get a reference to bs */ void bdrv_ref(BlockDriverState *bs) { bs->refcnt++; } /* Release a previously grabbed reference to bs. * If after releasing, reference count is zero, the BlockDriverState is * deleted. */ void bdrv_unref(BlockDriverState *bs) { if (!bs) { return; } assert(bs->refcnt > 0); if (--bs->refcnt == 0) { bdrv_delete(bs); } } struct BdrvOpBlocker { Error *reason; QLIST_ENTRY(BdrvOpBlocker) list; }; bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp) { BdrvOpBlocker *blocker; assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); if (!QLIST_EMPTY(&bs->op_blockers[op])) { blocker = QLIST_FIRST(&bs->op_blockers[op]); error_propagate_prepend(errp, error_copy(blocker->reason), "Node '%s' is busy: ", bdrv_get_device_or_node_name(bs)); return true; } return false; } void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason) { BdrvOpBlocker *blocker; assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); blocker = g_new0(BdrvOpBlocker, 1); blocker->reason = reason; QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list); } void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason) { BdrvOpBlocker *blocker, *next; assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) { if (blocker->reason == reason) { QLIST_REMOVE(blocker, list); g_free(blocker); } } } void bdrv_op_block_all(BlockDriverState *bs, Error *reason) { int i; for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { bdrv_op_block(bs, i, reason); } } void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason) { int i; for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { bdrv_op_unblock(bs, i, reason); } } bool bdrv_op_blocker_is_empty(BlockDriverState *bs) { int i; for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { if (!QLIST_EMPTY(&bs->op_blockers[i])) { return false; } } return true; } void bdrv_img_create(const char *filename, const char *fmt, const char *base_filename, const char *base_fmt, char *options, uint64_t img_size, int flags, bool quiet, Error **errp) { QemuOptsList *create_opts = NULL; QemuOpts *opts = NULL; const char *backing_fmt, *backing_file; int64_t size; BlockDriver *drv, *proto_drv; Error *local_err = NULL; int ret = 0; /* Find driver and parse its options */ drv = bdrv_find_format(fmt); if (!drv) { error_setg(errp, "Unknown file format '%s'", fmt); return; } proto_drv = bdrv_find_protocol(filename, true, errp); if (!proto_drv) { return; } if (!drv->create_opts) { error_setg(errp, "Format driver '%s' does not support image creation", drv->format_name); return; } if (!proto_drv->create_opts) { error_setg(errp, "Protocol driver '%s' does not support image creation", proto_drv->format_name); return; } /* Create parameter list */ create_opts = qemu_opts_append(create_opts, drv->create_opts); create_opts = qemu_opts_append(create_opts, proto_drv->create_opts); opts = qemu_opts_create(create_opts, NULL, 0, &error_abort); /* Parse -o options */ if (options) { if (!qemu_opts_do_parse(opts, options, NULL, errp)) { goto out; } } if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) { qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort); } else if (img_size != UINT64_C(-1)) { error_setg(errp, "The image size must be specified only once"); goto out; } if (base_filename) { if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename, NULL)) { error_setg(errp, "Backing file not supported for file format '%s'", fmt); goto out; } } if (base_fmt) { if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) { error_setg(errp, "Backing file format not supported for file " "format '%s'", fmt); goto out; } } backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE); if (backing_file) { if (!strcmp(filename, backing_file)) { error_setg(errp, "Error: Trying to create an image with the " "same filename as the backing file"); goto out; } if (backing_file[0] == '\0') { error_setg(errp, "Expected backing file name, got empty string"); goto out; } } backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT); /* The size for the image must always be specified, unless we have a backing * file and we have not been forbidden from opening it. */ size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size); if (backing_file && !(flags & BDRV_O_NO_BACKING)) { BlockDriverState *bs; char *full_backing; int back_flags; QDict *backing_options = NULL; full_backing = bdrv_get_full_backing_filename_from_filename(filename, backing_file, &local_err); if (local_err) { goto out; } assert(full_backing); /* backing files always opened read-only */ back_flags = flags; back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING); backing_options = qdict_new(); if (backing_fmt) { qdict_put_str(backing_options, "driver", backing_fmt); } qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true); bs = bdrv_open(full_backing, NULL, backing_options, back_flags, &local_err); g_free(full_backing); if (!bs) { error_append_hint(&local_err, "Could not open backing image.\n"); goto out; } else { if (!backing_fmt) { warn_report("Deprecated use of backing file without explicit " "backing format (detected format of %s)", bs->drv->format_name); if (bs->drv != &bdrv_raw) { /* * A probe of raw deserves the most attention: * leaving the backing format out of the image * will ensure bs->probed is set (ensuring we * don't accidentally commit into the backing * file), and allow more spots to warn the users * to fix their toolchain when opening this image * later. For other images, we can safely record * the format that we probed. */ backing_fmt = bs->drv->format_name; qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, backing_fmt, NULL); } } if (size == -1) { /* Opened BS, have no size */ size = bdrv_getlength(bs); if (size < 0) { error_setg_errno(errp, -size, "Could not get size of '%s'", backing_file); bdrv_unref(bs); goto out; } qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort); } bdrv_unref(bs); } /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */ } else if (backing_file && !backing_fmt) { warn_report("Deprecated use of unopened backing file without " "explicit backing format, use of this image requires " "potentially unsafe format probing"); } if (size == -1) { error_setg(errp, "Image creation needs a size parameter"); goto out; } if (!quiet) { printf("Formatting '%s', fmt=%s ", filename, fmt); qemu_opts_print(opts, " "); puts(""); fflush(stdout); } ret = bdrv_create(drv, filename, opts, &local_err); if (ret == -EFBIG) { /* This is generally a better message than whatever the driver would * deliver (especially because of the cluster_size_hint), since that * is most probably not much different from "image too large". */ const char *cluster_size_hint = ""; if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) { cluster_size_hint = " (try using a larger cluster size)"; } error_setg(errp, "The image size is too large for file format '%s'" "%s", fmt, cluster_size_hint); error_free(local_err); local_err = NULL; } out: qemu_opts_del(opts); qemu_opts_free(create_opts); error_propagate(errp, local_err); } AioContext *bdrv_get_aio_context(BlockDriverState *bs) { return bs ? bs->aio_context : qemu_get_aio_context(); } AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs) { Coroutine *self = qemu_coroutine_self(); AioContext *old_ctx = qemu_coroutine_get_aio_context(self); AioContext *new_ctx; /* * Increase bs->in_flight to ensure that this operation is completed before * moving the node to a different AioContext. Read new_ctx only afterwards. */ bdrv_inc_in_flight(bs); new_ctx = bdrv_get_aio_context(bs); aio_co_reschedule_self(new_ctx); return old_ctx; } void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx) { aio_co_reschedule_self(old_ctx); bdrv_dec_in_flight(bs); } void coroutine_fn bdrv_co_lock(BlockDriverState *bs) { AioContext *ctx = bdrv_get_aio_context(bs); /* In the main thread, bs->aio_context won't change concurrently */ assert(qemu_get_current_aio_context() == qemu_get_aio_context()); /* * We're in coroutine context, so we already hold the lock of the main * loop AioContext. Don't lock it twice to avoid deadlocks. */ assert(qemu_in_coroutine()); if (ctx != qemu_get_aio_context()) { aio_context_acquire(ctx); } } void coroutine_fn bdrv_co_unlock(BlockDriverState *bs) { AioContext *ctx = bdrv_get_aio_context(bs); assert(qemu_in_coroutine()); if (ctx != qemu_get_aio_context()) { aio_context_release(ctx); } } void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co) { aio_co_enter(bdrv_get_aio_context(bs), co); } static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban) { QLIST_REMOVE(ban, list); g_free(ban); } static void bdrv_detach_aio_context(BlockDriverState *bs) { BdrvAioNotifier *baf, *baf_tmp; assert(!bs->walking_aio_notifiers); bs->walking_aio_notifiers = true; QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) { if (baf->deleted) { bdrv_do_remove_aio_context_notifier(baf); } else { baf->detach_aio_context(baf->opaque); } } /* Never mind iterating again to check for ->deleted. bdrv_close() will * remove remaining aio notifiers if we aren't called again. */ bs->walking_aio_notifiers = false; if (bs->drv && bs->drv->bdrv_detach_aio_context) { bs->drv->bdrv_detach_aio_context(bs); } if (bs->quiesce_counter) { aio_enable_external(bs->aio_context); } bs->aio_context = NULL; } static void bdrv_attach_aio_context(BlockDriverState *bs, AioContext *new_context) { BdrvAioNotifier *ban, *ban_tmp; if (bs->quiesce_counter) { aio_disable_external(new_context); } bs->aio_context = new_context; if (bs->drv && bs->drv->bdrv_attach_aio_context) { bs->drv->bdrv_attach_aio_context(bs, new_context); } assert(!bs->walking_aio_notifiers); bs->walking_aio_notifiers = true; QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) { if (ban->deleted) { bdrv_do_remove_aio_context_notifier(ban); } else { ban->attached_aio_context(new_context, ban->opaque); } } bs->walking_aio_notifiers = false; } /* * Changes the AioContext used for fd handlers, timers, and BHs by this * BlockDriverState and all its children and parents. * * Must be called from the main AioContext. * * The caller must own the AioContext lock for the old AioContext of bs, but it * must not own the AioContext lock for new_context (unless new_context is the * same as the current context of bs). * * @ignore will accumulate all visited BdrvChild object. The caller is * responsible for freeing the list afterwards. */ void bdrv_set_aio_context_ignore(BlockDriverState *bs, AioContext *new_context, GSList **ignore) { AioContext *old_context = bdrv_get_aio_context(bs); GSList *children_to_process = NULL; GSList *parents_to_process = NULL; GSList *entry; BdrvChild *child, *parent; g_assert(qemu_get_current_aio_context() == qemu_get_aio_context()); if (old_context == new_context) { return; } bdrv_drained_begin(bs); QLIST_FOREACH(child, &bs->children, next) { if (g_slist_find(*ignore, child)) { continue; } *ignore = g_slist_prepend(*ignore, child); children_to_process = g_slist_prepend(children_to_process, child); } QLIST_FOREACH(parent, &bs->parents, next_parent) { if (g_slist_find(*ignore, parent)) { continue; } *ignore = g_slist_prepend(*ignore, parent); parents_to_process = g_slist_prepend(parents_to_process, parent); } for (entry = children_to_process; entry != NULL; entry = g_slist_next(entry)) { child = entry->data; bdrv_set_aio_context_ignore(child->bs, new_context, ignore); } g_slist_free(children_to_process); for (entry = parents_to_process; entry != NULL; entry = g_slist_next(entry)) { parent = entry->data; assert(parent->klass->set_aio_ctx); parent->klass->set_aio_ctx(parent, new_context, ignore); } g_slist_free(parents_to_process); bdrv_detach_aio_context(bs); /* Acquire the new context, if necessary */ if (qemu_get_aio_context() != new_context) { aio_context_acquire(new_context); } bdrv_attach_aio_context(bs, new_context); /* * If this function was recursively called from * bdrv_set_aio_context_ignore(), there may be nodes in the * subtree that have not yet been moved to the new AioContext. * Release the old one so bdrv_drained_end() can poll them. */ if (qemu_get_aio_context() != old_context) { aio_context_release(old_context); } bdrv_drained_end(bs); if (qemu_get_aio_context() != old_context) { aio_context_acquire(old_context); } if (qemu_get_aio_context() != new_context) { aio_context_release(new_context); } } static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx, GSList **ignore, Error **errp) { if (g_slist_find(*ignore, c)) { return true; } *ignore = g_slist_prepend(*ignore, c); /* * A BdrvChildClass that doesn't handle AioContext changes cannot * tolerate any AioContext changes */ if (!c->klass->can_set_aio_ctx) { char *user = bdrv_child_user_desc(c); error_setg(errp, "Changing iothreads is not supported by %s", user); g_free(user); return false; } if (!c->klass->can_set_aio_ctx(c, ctx, ignore, errp)) { assert(!errp || *errp); return false; } return true; } bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx, GSList **ignore, Error **errp) { if (g_slist_find(*ignore, c)) { return true; } *ignore = g_slist_prepend(*ignore, c); return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp); } /* @ignore will accumulate all visited BdrvChild object. The caller is * responsible for freeing the list afterwards. */ bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx, GSList **ignore, Error **errp) { BdrvChild *c; if (bdrv_get_aio_context(bs) == ctx) { return true; } QLIST_FOREACH(c, &bs->parents, next_parent) { if (!bdrv_parent_can_set_aio_context(c, ctx, ignore, errp)) { return false; } } QLIST_FOREACH(c, &bs->children, next) { if (!bdrv_child_can_set_aio_context(c, ctx, ignore, errp)) { return false; } } return true; } int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, BdrvChild *ignore_child, Error **errp) { GSList *ignore; bool ret; ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL; ret = bdrv_can_set_aio_context(bs, ctx, &ignore, errp); g_slist_free(ignore); if (!ret) { return -EPERM; } ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL; bdrv_set_aio_context_ignore(bs, ctx, &ignore); g_slist_free(ignore); return 0; } int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, Error **errp) { return bdrv_child_try_set_aio_context(bs, ctx, NULL, errp); } void bdrv_add_aio_context_notifier(BlockDriverState *bs, void (*attached_aio_context)(AioContext *new_context, void *opaque), void (*detach_aio_context)(void *opaque), void *opaque) { BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1); *ban = (BdrvAioNotifier){ .attached_aio_context = attached_aio_context, .detach_aio_context = detach_aio_context, .opaque = opaque }; QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list); } void bdrv_remove_aio_context_notifier(BlockDriverState *bs, void (*attached_aio_context)(AioContext *, void *), void (*detach_aio_context)(void *), void *opaque) { BdrvAioNotifier *ban, *ban_next; QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { if (ban->attached_aio_context == attached_aio_context && ban->detach_aio_context == detach_aio_context && ban->opaque == opaque && ban->deleted == false) { if (bs->walking_aio_notifiers) { ban->deleted = true; } else { bdrv_do_remove_aio_context_notifier(ban); } return; } } abort(); } int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts, BlockDriverAmendStatusCB *status_cb, void *cb_opaque, bool force, Error **errp) { if (!bs->drv) { error_setg(errp, "Node is ejected"); return -ENOMEDIUM; } if (!bs->drv->bdrv_amend_options) { error_setg(errp, "Block driver '%s' does not support option amendment", bs->drv->format_name); return -ENOTSUP; } return bs->drv->bdrv_amend_options(bs, opts, status_cb, cb_opaque, force, errp); } /* * This function checks whether the given @to_replace is allowed to be * replaced by a node that always shows the same data as @bs. This is * used for example to verify whether the mirror job can replace * @to_replace by the target mirrored from @bs. * To be replaceable, @bs and @to_replace may either be guaranteed to * always show the same data (because they are only connected through * filters), or some driver may allow replacing one of its children * because it can guarantee that this child's data is not visible at * all (for example, for dissenting quorum children that have no other * parents). */ bool bdrv_recurse_can_replace(BlockDriverState *bs, BlockDriverState *to_replace) { BlockDriverState *filtered; if (!bs || !bs->drv) { return false; } if (bs == to_replace) { return true; } /* See what the driver can do */ if (bs->drv->bdrv_recurse_can_replace) { return bs->drv->bdrv_recurse_can_replace(bs, to_replace); } /* For filters without an own implementation, we can recurse on our own */ filtered = bdrv_filter_bs(bs); if (filtered) { return bdrv_recurse_can_replace(filtered, to_replace); } /* Safe default */ return false; } /* * Check whether the given @node_name can be replaced by a node that * has the same data as @parent_bs. If so, return @node_name's BDS; * NULL otherwise. * * @node_name must be a (recursive) *child of @parent_bs (or this * function will return NULL). * * The result (whether the node can be replaced or not) is only valid * for as long as no graph or permission changes occur. */ BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs, const char *node_name, Error **errp) { BlockDriverState *to_replace_bs = bdrv_find_node(node_name); AioContext *aio_context; if (!to_replace_bs) { error_setg(errp, "Failed to find node with node-name='%s'", node_name); return NULL; } aio_context = bdrv_get_aio_context(to_replace_bs); aio_context_acquire(aio_context); if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) { to_replace_bs = NULL; goto out; } /* We don't want arbitrary node of the BDS chain to be replaced only the top * most non filter in order to prevent data corruption. * Another benefit is that this tests exclude backing files which are * blocked by the backing blockers. */ if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) { error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', " "because it cannot be guaranteed that doing so would not " "lead to an abrupt change of visible data", node_name, parent_bs->node_name); to_replace_bs = NULL; goto out; } out: aio_context_release(aio_context); return to_replace_bs; } /** * Iterates through the list of runtime option keys that are said to * be "strong" for a BDS. An option is called "strong" if it changes * a BDS's data. For example, the null block driver's "size" and * "read-zeroes" options are strong, but its "latency-ns" option is * not. * * If a key returned by this function ends with a dot, all options * starting with that prefix are strong. */ static const char *const *strong_options(BlockDriverState *bs, const char *const *curopt) { static const char *const global_options[] = { "driver", "filename", NULL }; if (!curopt) { return &global_options[0]; } curopt++; if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) { curopt = bs->drv->strong_runtime_opts; } return (curopt && *curopt) ? curopt : NULL; } /** * Copies all strong runtime options from bs->options to the given * QDict. The set of strong option keys is determined by invoking * strong_options(). * * Returns true iff any strong option was present in bs->options (and * thus copied to the target QDict) with the exception of "filename" * and "driver". The caller is expected to use this value to decide * whether the existence of strong options prevents the generation of * a plain filename. */ static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs) { bool found_any = false; const char *const *option_name = NULL; if (!bs->drv) { return false; } while ((option_name = strong_options(bs, option_name))) { bool option_given = false; assert(strlen(*option_name) > 0); if ((*option_name)[strlen(*option_name) - 1] != '.') { QObject *entry = qdict_get(bs->options, *option_name); if (!entry) { continue; } qdict_put_obj(d, *option_name, qobject_ref(entry)); option_given = true; } else { const QDictEntry *entry; for (entry = qdict_first(bs->options); entry; entry = qdict_next(bs->options, entry)) { if (strstart(qdict_entry_key(entry), *option_name, NULL)) { qdict_put_obj(d, qdict_entry_key(entry), qobject_ref(qdict_entry_value(entry))); option_given = true; } } } /* While "driver" and "filename" need to be included in a JSON filename, * their existence does not prohibit generation of a plain filename. */ if (!found_any && option_given && strcmp(*option_name, "driver") && strcmp(*option_name, "filename")) { found_any = true; } } if (!qdict_haskey(d, "driver")) { /* Drivers created with bdrv_new_open_driver() may not have a * @driver option. Add it here. */ qdict_put_str(d, "driver", bs->drv->format_name); } return found_any; } /* Note: This function may return false positives; it may return true * even if opening the backing file specified by bs's image header * would result in exactly bs->backing. */ bool bdrv_backing_overridden(BlockDriverState *bs) { if (bs->backing) { return strcmp(bs->auto_backing_file, bs->backing->bs->filename); } else { /* No backing BDS, so if the image header reports any backing * file, it must have been suppressed */ return bs->auto_backing_file[0] != '\0'; } } /* Updates the following BDS fields: * - exact_filename: A filename which may be used for opening a block device * which (mostly) equals the given BDS (even without any * other options; so reading and writing must return the same * results, but caching etc. may be different) * - full_open_options: Options which, when given when opening a block device * (without a filename), result in a BDS (mostly) * equalling the given one * - filename: If exact_filename is set, it is copied here. Otherwise, * full_open_options is converted to a JSON object, prefixed with * "json:" (for use through the JSON pseudo protocol) and put here. */ void bdrv_refresh_filename(BlockDriverState *bs) { BlockDriver *drv = bs->drv; BdrvChild *child; BlockDriverState *primary_child_bs; QDict *opts; bool backing_overridden; bool generate_json_filename; /* Whether our default implementation should fill exact_filename (false) or not (true) */ if (!drv) { return; } /* This BDS's file name may depend on any of its children's file names, so * refresh those first */ QLIST_FOREACH(child, &bs->children, next) { bdrv_refresh_filename(child->bs); } if (bs->implicit) { /* For implicit nodes, just copy everything from the single child */ child = QLIST_FIRST(&bs->children); assert(QLIST_NEXT(child, next) == NULL); pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), child->bs->exact_filename); pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename); qobject_unref(bs->full_open_options); bs->full_open_options = qobject_ref(child->bs->full_open_options); return; } backing_overridden = bdrv_backing_overridden(bs); if (bs->open_flags & BDRV_O_NO_IO) { /* Without I/O, the backing file does not change anything. * Therefore, in such a case (primarily qemu-img), we can * pretend the backing file has not been overridden even if * it technically has been. */ backing_overridden = false; } /* Gather the options QDict */ opts = qdict_new(); generate_json_filename = append_strong_runtime_options(opts, bs); generate_json_filename |= backing_overridden; if (drv->bdrv_gather_child_options) { /* Some block drivers may not want to present all of their children's * options, or name them differently from BdrvChild.name */ drv->bdrv_gather_child_options(bs, opts, backing_overridden); } else { QLIST_FOREACH(child, &bs->children, next) { if (child == bs->backing && !backing_overridden) { /* We can skip the backing BDS if it has not been overridden */ continue; } qdict_put(opts, child->name, qobject_ref(child->bs->full_open_options)); } if (backing_overridden && !bs->backing) { /* Force no backing file */ qdict_put_null(opts, "backing"); } } qobject_unref(bs->full_open_options); bs->full_open_options = opts; primary_child_bs = bdrv_primary_bs(bs); if (drv->bdrv_refresh_filename) { /* Obsolete information is of no use here, so drop the old file name * information before refreshing it */ bs->exact_filename[0] = '\0'; drv->bdrv_refresh_filename(bs); } else if (primary_child_bs) { /* * Try to reconstruct valid information from the underlying * file -- this only works for format nodes (filter nodes * cannot be probed and as such must be selected by the user * either through an options dict, or through a special * filename which the filter driver must construct in its * .bdrv_refresh_filename() implementation). */ bs->exact_filename[0] = '\0'; /* * We can use the underlying file's filename if: * - it has a filename, * - the current BDS is not a filter, * - the file is a protocol BDS, and * - opening that file (as this BDS's format) will automatically create * the BDS tree we have right now, that is: * - the user did not significantly change this BDS's behavior with * some explicit (strong) options * - no non-file child of this BDS has been overridden by the user * Both of these conditions are represented by generate_json_filename. */ if (primary_child_bs->exact_filename[0] && primary_child_bs->drv->bdrv_file_open && !drv->is_filter && !generate_json_filename) { strcpy(bs->exact_filename, primary_child_bs->exact_filename); } } if (bs->exact_filename[0]) { pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename); } else { GString *json = qobject_to_json(QOBJECT(bs->full_open_options)); if (snprintf(bs->filename, sizeof(bs->filename), "json:%s", json->str) >= sizeof(bs->filename)) { /* Give user a hint if we truncated things. */ strcpy(bs->filename + sizeof(bs->filename) - 4, "..."); } g_string_free(json, true); } } char *bdrv_dirname(BlockDriverState *bs, Error **errp) { BlockDriver *drv = bs->drv; BlockDriverState *child_bs; if (!drv) { error_setg(errp, "Node '%s' is ejected", bs->node_name); return NULL; } if (drv->bdrv_dirname) { return drv->bdrv_dirname(bs, errp); } child_bs = bdrv_primary_bs(bs); if (child_bs) { return bdrv_dirname(child_bs, errp); } bdrv_refresh_filename(bs); if (bs->exact_filename[0] != '\0') { return path_combine(bs->exact_filename, ""); } error_setg(errp, "Cannot generate a base directory for %s nodes", drv->format_name); return NULL; } /* * Hot add/remove a BDS's child. So the user can take a child offline when * it is broken and take a new child online */ void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs, Error **errp) { if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) { error_setg(errp, "The node %s does not support adding a child", bdrv_get_device_or_node_name(parent_bs)); return; } if (!QLIST_EMPTY(&child_bs->parents)) { error_setg(errp, "The node %s already has a parent", child_bs->node_name); return; } parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp); } void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) { BdrvChild *tmp; if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) { error_setg(errp, "The node %s does not support removing a child", bdrv_get_device_or_node_name(parent_bs)); return; } QLIST_FOREACH(tmp, &parent_bs->children, next) { if (tmp == child) { break; } } if (!tmp) { error_setg(errp, "The node %s does not have a child named %s", bdrv_get_device_or_node_name(parent_bs), bdrv_get_device_or_node_name(child->bs)); return; } parent_bs->drv->bdrv_del_child(parent_bs, child, errp); } int bdrv_make_empty(BdrvChild *c, Error **errp) { BlockDriver *drv = c->bs->drv; int ret; assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)); if (!drv->bdrv_make_empty) { error_setg(errp, "%s does not support emptying nodes", drv->format_name); return -ENOTSUP; } ret = drv->bdrv_make_empty(c->bs); if (ret < 0) { error_setg_errno(errp, -ret, "Failed to empty %s", c->bs->filename); return ret; } return 0; } /* * Return the child that @bs acts as an overlay for, and from which data may be * copied in COW or COR operations. Usually this is the backing file. */ BdrvChild *bdrv_cow_child(BlockDriverState *bs) { if (!bs || !bs->drv) { return NULL; } if (bs->drv->is_filter) { return NULL; } if (!bs->backing) { return NULL; } assert(bs->backing->role & BDRV_CHILD_COW); return bs->backing; } /* * If @bs acts as a filter for exactly one of its children, return * that child. */ BdrvChild *bdrv_filter_child(BlockDriverState *bs) { BdrvChild *c; if (!bs || !bs->drv) { return NULL; } if (!bs->drv->is_filter) { return NULL; } /* Only one of @backing or @file may be used */ assert(!(bs->backing && bs->file)); c = bs->backing ?: bs->file; if (!c) { return NULL; } assert(c->role & BDRV_CHILD_FILTERED); return c; } /* * Return either the result of bdrv_cow_child() or bdrv_filter_child(), * whichever is non-NULL. * * Return NULL if both are NULL. */ BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs) { BdrvChild *cow_child = bdrv_cow_child(bs); BdrvChild *filter_child = bdrv_filter_child(bs); /* Filter nodes cannot have COW backing files */ assert(!(cow_child && filter_child)); return cow_child ?: filter_child; } /* * Return the primary child of this node: For filters, that is the * filtered child. For other nodes, that is usually the child storing * metadata. * (A generally more helpful description is that this is (usually) the * child that has the same filename as @bs.) * * Drivers do not necessarily have a primary child; for example quorum * does not. */ BdrvChild *bdrv_primary_child(BlockDriverState *bs) { BdrvChild *c, *found = NULL; QLIST_FOREACH(c, &bs->children, next) { if (c->role & BDRV_CHILD_PRIMARY) { assert(!found); found = c; } } return found; } static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs, bool stop_on_explicit_filter) { BdrvChild *c; if (!bs) { return NULL; } while (!(stop_on_explicit_filter && !bs->implicit)) { c = bdrv_filter_child(bs); if (!c) { /* * A filter that is embedded in a working block graph must * have a child. Assert this here so this function does * not return a filter node that is not expected by the * caller. */ assert(!bs->drv || !bs->drv->is_filter); break; } bs = c->bs; } /* * Note that this treats nodes with bs->drv == NULL as not being * filters (bs->drv == NULL should be replaced by something else * anyway). * The advantage of this behavior is that this function will thus * always return a non-NULL value (given a non-NULL @bs). */ return bs; } /* * Return the first BDS that has not been added implicitly or that * does not have a filtered child down the chain starting from @bs * (including @bs itself). */ BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs) { return bdrv_do_skip_filters(bs, true); } /* * Return the first BDS that does not have a filtered child down the * chain starting from @bs (including @bs itself). */ BlockDriverState *bdrv_skip_filters(BlockDriverState *bs) { return bdrv_do_skip_filters(bs, false); } /* * For a backing chain, return the first non-filter backing image of * the first non-filter image. */ BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs) { return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs))); }