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qemu/block/io.c
Fam Zheng 51288d7917 block: Introduce "drained begin/end" API 
The semantics is that after bdrv_drained_begin(bs), bs will not get new external
requests until the matching bdrv_drained_end(bs).

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-10-23 18:18:24 +02:00

2644 lines
78 KiB
C
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/*
* Block layer I/O functions
*
* 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 "trace.h"
#include "sysemu/block-backend.h"
#include "block/blockjob.h"
#include "block/block_int.h"
#include "block/throttle-groups.h"
#include "qemu/error-report.h"
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
static BlockAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque);
static BlockAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque);
static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov);
static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov);
static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags);
static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags);
static BlockAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
BdrvRequestFlags flags,
BlockCompletionFunc *cb,
void *opaque,
bool is_write);
static void coroutine_fn bdrv_co_do_rw(void *opaque);
static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags);
/* throttling disk I/O limits */
void bdrv_set_io_limits(BlockDriverState *bs,
ThrottleConfig *cfg)
{
int i;
throttle_group_config(bs, cfg);
for (i = 0; i < 2; i++) {
qemu_co_enter_next(&bs->throttled_reqs[i]);
}
}
/* this function drain all the throttled IOs */
static bool bdrv_start_throttled_reqs(BlockDriverState *bs)
{
bool drained = false;
bool enabled = bs->io_limits_enabled;
int i;
bs->io_limits_enabled = false;
for (i = 0; i < 2; i++) {
while (qemu_co_enter_next(&bs->throttled_reqs[i])) {
drained = true;
}
}
bs->io_limits_enabled = enabled;
return drained;
}
void bdrv_io_limits_disable(BlockDriverState *bs)
{
bs->io_limits_enabled = false;
bdrv_start_throttled_reqs(bs);
throttle_group_unregister_bs(bs);
}
/* should be called before bdrv_set_io_limits if a limit is set */
void bdrv_io_limits_enable(BlockDriverState *bs, const char *group)
{
assert(!bs->io_limits_enabled);
throttle_group_register_bs(bs, group);
bs->io_limits_enabled = true;
}
void bdrv_io_limits_update_group(BlockDriverState *bs, const char *group)
{
/* this bs is not part of any group */
if (!bs->throttle_state) {
return;
}
/* this bs is a part of the same group than the one we want */
if (!g_strcmp0(throttle_group_get_name(bs), group)) {
return;
}
/* need to change the group this bs belong to */
bdrv_io_limits_disable(bs);
bdrv_io_limits_enable(bs, group);
}
void bdrv_setup_io_funcs(BlockDriver *bdrv)
{
/* Block drivers without coroutine functions need emulation */
if (!bdrv->bdrv_co_readv) {
bdrv->bdrv_co_readv = bdrv_co_readv_em;
bdrv->bdrv_co_writev = bdrv_co_writev_em;
/* bdrv_co_readv_em()/brdv_co_writev_em() work in terms of aio, so if
* the block driver lacks aio we need to emulate that too.
*/
if (!bdrv->bdrv_aio_readv) {
/* add AIO emulation layer */
bdrv->bdrv_aio_readv = bdrv_aio_readv_em;
bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
}
}
}
void bdrv_refresh_limits(BlockDriverState *bs, Error **errp)
{
BlockDriver *drv = bs->drv;
Error *local_err = NULL;
memset(&bs->bl, 0, sizeof(bs->bl));
if (!drv) {
return;
}
/* Take some limits from the children as a default */
if (bs->file) {
bdrv_refresh_limits(bs->file->bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
bs->bl.opt_transfer_length = bs->file->bs->bl.opt_transfer_length;
bs->bl.max_transfer_length = bs->file->bs->bl.max_transfer_length;
bs->bl.min_mem_alignment = bs->file->bs->bl.min_mem_alignment;
bs->bl.opt_mem_alignment = bs->file->bs->bl.opt_mem_alignment;
} else {
bs->bl.min_mem_alignment = 512;
bs->bl.opt_mem_alignment = getpagesize();
}
if (bs->backing) {
bdrv_refresh_limits(bs->backing->bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
bs->bl.opt_transfer_length =
MAX(bs->bl.opt_transfer_length,
bs->backing->bs->bl.opt_transfer_length);
bs->bl.max_transfer_length =
MIN_NON_ZERO(bs->bl.max_transfer_length,
bs->backing->bs->bl.max_transfer_length);
bs->bl.opt_mem_alignment =
MAX(bs->bl.opt_mem_alignment,
bs->backing->bs->bl.opt_mem_alignment);
bs->bl.min_mem_alignment =
MAX(bs->bl.min_mem_alignment,
bs->backing->bs->bl.min_mem_alignment);
}
/* Then let the driver override it */
if (drv->bdrv_refresh_limits) {
drv->bdrv_refresh_limits(bs, errp);
}
}
/**
* The copy-on-read flag is actually a reference count so multiple users may
* use the feature without worrying about clobbering its previous state.
* Copy-on-read stays enabled until all users have called to disable it.
*/
void bdrv_enable_copy_on_read(BlockDriverState *bs)
{
bs->copy_on_read++;
}
void bdrv_disable_copy_on_read(BlockDriverState *bs)
{
assert(bs->copy_on_read > 0);
bs->copy_on_read--;
}
/* Check if any requests are in-flight (including throttled requests) */
bool bdrv_requests_pending(BlockDriverState *bs)
{
if (!QLIST_EMPTY(&bs->tracked_requests)) {
return true;
}
if (!qemu_co_queue_empty(&bs->throttled_reqs[0])) {
return true;
}
if (!qemu_co_queue_empty(&bs->throttled_reqs[1])) {
return true;
}
if (bs->file && bdrv_requests_pending(bs->file->bs)) {
return true;
}
if (bs->backing && bdrv_requests_pending(bs->backing->bs)) {
return true;
}
return false;
}
/*
* Wait for pending requests to complete on a single BlockDriverState subtree
*
* Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState
* AioContext.
*
* Only this BlockDriverState's AioContext is run, so in-flight requests must
* not depend on events in other AioContexts. In that case, use
* bdrv_drain_all() instead.
*/
void bdrv_drain(BlockDriverState *bs)
{
bool busy = true;
while (busy) {
/* Keep iterating */
bdrv_flush_io_queue(bs);
busy = bdrv_requests_pending(bs);
busy |= aio_poll(bdrv_get_aio_context(bs), busy);
}
}
/*
* Wait for pending requests to complete across all BlockDriverStates
*
* This function does not flush data to disk, use bdrv_flush_all() for that
* after calling this function.
*/
void bdrv_drain_all(void)
{
/* Always run first iteration so any pending completion BHs run */
bool busy = true;
BlockDriverState *bs = NULL;
GSList *aio_ctxs = NULL, *ctx;
while ((bs = bdrv_next(bs))) {
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
if (bs->job) {
block_job_pause(bs->job);
}
aio_context_release(aio_context);
if (!g_slist_find(aio_ctxs, aio_context)) {
aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
}
}
/* Note that completion of an asynchronous I/O operation can trigger any
* number of other I/O operations on other devices---for example a
* coroutine can submit an I/O request to another device in response to
* request completion. Therefore we must keep looping until there was no
* more activity rather than simply draining each device independently.
*/
while (busy) {
busy = false;
for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
AioContext *aio_context = ctx->data;
bs = NULL;
aio_context_acquire(aio_context);
while ((bs = bdrv_next(bs))) {
if (aio_context == bdrv_get_aio_context(bs)) {
bdrv_flush_io_queue(bs);
if (bdrv_requests_pending(bs)) {
busy = true;
aio_poll(aio_context, busy);
}
}
}
busy |= aio_poll(aio_context, false);
aio_context_release(aio_context);
}
}
bs = NULL;
while ((bs = bdrv_next(bs))) {
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
if (bs->job) {
block_job_resume(bs->job);
}
aio_context_release(aio_context);
}
g_slist_free(aio_ctxs);
}
/**
* Remove an active request from the tracked requests list
*
* This function should be called when a tracked request is completing.
*/
static void tracked_request_end(BdrvTrackedRequest *req)
{
if (req->serialising) {
req->bs->serialising_in_flight--;
}
QLIST_REMOVE(req, list);
qemu_co_queue_restart_all(&req->wait_queue);
}
/**
* Add an active request to the tracked requests list
*/
static void tracked_request_begin(BdrvTrackedRequest *req,
BlockDriverState *bs,
int64_t offset,
unsigned int bytes, bool is_write)
{
*req = (BdrvTrackedRequest){
.bs = bs,
.offset = offset,
.bytes = bytes,
.is_write = is_write,
.co = qemu_coroutine_self(),
.serialising = false,
.overlap_offset = offset,
.overlap_bytes = bytes,
};
qemu_co_queue_init(&req->wait_queue);
QLIST_INSERT_HEAD(&bs->tracked_requests, req, list);
}
static void mark_request_serialising(BdrvTrackedRequest *req, uint64_t align)
{
int64_t overlap_offset = req->offset & ~(align - 1);
unsigned int overlap_bytes = ROUND_UP(req->offset + req->bytes, align)
- overlap_offset;
if (!req->serialising) {
req->bs->serialising_in_flight++;
req->serialising = true;
}
req->overlap_offset = MIN(req->overlap_offset, overlap_offset);
req->overlap_bytes = MAX(req->overlap_bytes, overlap_bytes);
}
/**
* Round a region to cluster boundaries
*/
void bdrv_round_to_clusters(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
int64_t *cluster_sector_num,
int *cluster_nb_sectors)
{
BlockDriverInfo bdi;
if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) {
*cluster_sector_num = sector_num;
*cluster_nb_sectors = nb_sectors;
} else {
int64_t c = bdi.cluster_size / BDRV_SECTOR_SIZE;
*cluster_sector_num = QEMU_ALIGN_DOWN(sector_num, c);
*cluster_nb_sectors = QEMU_ALIGN_UP(sector_num - *cluster_sector_num +
nb_sectors, c);
}
}
static int bdrv_get_cluster_size(BlockDriverState *bs)
{
BlockDriverInfo bdi;
int ret;
ret = bdrv_get_info(bs, &bdi);
if (ret < 0 || bdi.cluster_size == 0) {
return bs->request_alignment;
} else {
return bdi.cluster_size;
}
}
static bool tracked_request_overlaps(BdrvTrackedRequest *req,
int64_t offset, unsigned int bytes)
{
/* aaaa bbbb */
if (offset >= req->overlap_offset + req->overlap_bytes) {
return false;
}
/* bbbb aaaa */
if (req->overlap_offset >= offset + bytes) {
return false;
}
return true;
}
static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)
{
BlockDriverState *bs = self->bs;
BdrvTrackedRequest *req;
bool retry;
bool waited = false;
if (!bs->serialising_in_flight) {
return false;
}
do {
retry = false;
QLIST_FOREACH(req, &bs->tracked_requests, list) {
if (req == self || (!req->serialising && !self->serialising)) {
continue;
}
if (tracked_request_overlaps(req, self->overlap_offset,
self->overlap_bytes))
{
/* Hitting this means there was a reentrant request, for
* example, a block driver issuing nested requests. This must
* never happen since it means deadlock.
*/
assert(qemu_coroutine_self() != req->co);
/* If the request is already (indirectly) waiting for us, or
* will wait for us as soon as it wakes up, then just go on
* (instead of producing a deadlock in the former case). */
if (!req->waiting_for) {
self->waiting_for = req;
qemu_co_queue_wait(&req->wait_queue);
self->waiting_for = NULL;
retry = true;
waited = true;
break;
}
}
}
} while (retry);
return waited;
}
static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
size_t size)
{
if (size > BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS) {
return -EIO;
}
if (!bdrv_is_inserted(bs)) {
return -ENOMEDIUM;
}
if (offset < 0) {
return -EIO;
}
return 0;
}
static int bdrv_check_request(BlockDriverState *bs, int64_t sector_num,
int nb_sectors)
{
if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return -EIO;
}
return bdrv_check_byte_request(bs, sector_num * BDRV_SECTOR_SIZE,
nb_sectors * BDRV_SECTOR_SIZE);
}
typedef struct RwCo {
BlockDriverState *bs;
int64_t offset;
QEMUIOVector *qiov;
bool is_write;
int ret;
BdrvRequestFlags flags;
} RwCo;
static void coroutine_fn bdrv_rw_co_entry(void *opaque)
{
RwCo *rwco = opaque;
if (!rwco->is_write) {
rwco->ret = bdrv_co_do_preadv(rwco->bs, rwco->offset,
rwco->qiov->size, rwco->qiov,
rwco->flags);
} else {
rwco->ret = bdrv_co_do_pwritev(rwco->bs, rwco->offset,
rwco->qiov->size, rwco->qiov,
rwco->flags);
}
}
/*
* Process a vectored synchronous request using coroutines
*/
static int bdrv_prwv_co(BlockDriverState *bs, int64_t offset,
QEMUIOVector *qiov, bool is_write,
BdrvRequestFlags flags)
{
Coroutine *co;
RwCo rwco = {
.bs = bs,
.offset = offset,
.qiov = qiov,
.is_write = is_write,
.ret = NOT_DONE,
.flags = flags,
};
/**
* In sync call context, when the vcpu is blocked, this throttling timer
* will not fire; so the I/O throttling function has to be disabled here
* if it has been enabled.
*/
if (bs->io_limits_enabled) {
fprintf(stderr, "Disabling I/O throttling on '%s' due "
"to synchronous I/O.\n", bdrv_get_device_name(bs));
bdrv_io_limits_disable(bs);
}
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_rw_co_entry(&rwco);
} else {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_rw_co_entry);
qemu_coroutine_enter(co, &rwco);
while (rwco.ret == NOT_DONE) {
aio_poll(aio_context, true);
}
}
return rwco.ret;
}
/*
* Process a synchronous request using coroutines
*/
static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
int nb_sectors, bool is_write, BdrvRequestFlags flags)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = nb_sectors * BDRV_SECTOR_SIZE,
};
if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return -EINVAL;
}
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_prwv_co(bs, sector_num << BDRV_SECTOR_BITS,
&qiov, is_write, flags);
}
/* return < 0 if error. See bdrv_write() for the return codes */
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
return bdrv_rw_co(bs, sector_num, buf, nb_sectors, false, 0);
}
/* Just like bdrv_read(), but with I/O throttling temporarily disabled */
int bdrv_read_unthrottled(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
bool enabled;
int ret;
enabled = bs->io_limits_enabled;
bs->io_limits_enabled = false;
ret = bdrv_read(bs, sector_num, buf, nb_sectors);
bs->io_limits_enabled = enabled;
return ret;
}
/* Return < 0 if error. Important errors are:
-EIO generic I/O error (may happen for all errors)
-ENOMEDIUM No media inserted.
-EINVAL Invalid sector number or nb_sectors
-EACCES Trying to write a read-only device
*/
int bdrv_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
return bdrv_rw_co(bs, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
}
int bdrv_write_zeroes(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, BdrvRequestFlags flags)
{
return bdrv_rw_co(bs, sector_num, NULL, nb_sectors, true,
BDRV_REQ_ZERO_WRITE | flags);
}
/*
* Completely zero out a block device with the help of bdrv_write_zeroes.
* The operation is sped up by checking the block status and only writing
* zeroes to the device if they currently do not return zeroes. Optional
* flags are passed through to bdrv_write_zeroes (e.g. BDRV_REQ_MAY_UNMAP).
*
* Returns < 0 on error, 0 on success. For error codes see bdrv_write().
*/
int bdrv_make_zero(BlockDriverState *bs, BdrvRequestFlags flags)
{
int64_t target_sectors, ret, nb_sectors, sector_num = 0;
int n;
target_sectors = bdrv_nb_sectors(bs);
if (target_sectors < 0) {
return target_sectors;
}
for (;;) {
nb_sectors = MIN(target_sectors - sector_num, BDRV_REQUEST_MAX_SECTORS);
if (nb_sectors <= 0) {
return 0;
}
ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n);
if (ret < 0) {
error_report("error getting block status at sector %" PRId64 ": %s",
sector_num, strerror(-ret));
return ret;
}
if (ret & BDRV_BLOCK_ZERO) {
sector_num += n;
continue;
}
ret = bdrv_write_zeroes(bs, sector_num, n, flags);
if (ret < 0) {
error_report("error writing zeroes at sector %" PRId64 ": %s",
sector_num, strerror(-ret));
return ret;
}
sector_num += n;
}
}
int bdrv_pread(BlockDriverState *bs, int64_t offset, void *buf, int bytes)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = bytes,
};
int ret;
if (bytes < 0) {
return -EINVAL;
}
qemu_iovec_init_external(&qiov, &iov, 1);
ret = bdrv_prwv_co(bs, offset, &qiov, false, 0);
if (ret < 0) {
return ret;
}
return bytes;
}
int bdrv_pwritev(BlockDriverState *bs, int64_t offset, QEMUIOVector *qiov)
{
int ret;
ret = bdrv_prwv_co(bs, offset, qiov, true, 0);
if (ret < 0) {
return ret;
}
return qiov->size;
}
int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
const void *buf, int bytes)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *) buf,
.iov_len = bytes,
};
if (bytes < 0) {
return -EINVAL;
}
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_pwritev(bs, offset, &qiov);
}
/*
* Writes to the file and ensures that no writes are reordered across this
* request (acts as a barrier)
*
* Returns 0 on success, -errno in error cases.
*/
int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset,
const void *buf, int count)
{
int ret;
ret = bdrv_pwrite(bs, offset, buf, count);
if (ret < 0) {
return ret;
}
/* No flush needed for cache modes that already do it */
if (bs->enable_write_cache) {
bdrv_flush(bs);
}
return 0;
}
static int coroutine_fn bdrv_co_do_copy_on_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
/* Perform I/O through a temporary buffer so that users who scribble over
* their read buffer while the operation is in progress do not end up
* modifying the image file. This is critical for zero-copy guest I/O
* where anything might happen inside guest memory.
*/
void *bounce_buffer;
BlockDriver *drv = bs->drv;
struct iovec iov;
QEMUIOVector bounce_qiov;
int64_t cluster_sector_num;
int cluster_nb_sectors;
size_t skip_bytes;
int ret;
/* Cover entire cluster so no additional backing file I/O is required when
* allocating cluster in the image file.
*/
bdrv_round_to_clusters(bs, sector_num, nb_sectors,
&cluster_sector_num, &cluster_nb_sectors);
trace_bdrv_co_do_copy_on_readv(bs, sector_num, nb_sectors,
cluster_sector_num, cluster_nb_sectors);
iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE;
iov.iov_base = bounce_buffer = qemu_try_blockalign(bs, iov.iov_len);
if (bounce_buffer == NULL) {
ret = -ENOMEM;
goto err;
}
qemu_iovec_init_external(&bounce_qiov, &iov, 1);
ret = drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors,
&bounce_qiov);
if (ret < 0) {
goto err;
}
if (drv->bdrv_co_write_zeroes &&
buffer_is_zero(bounce_buffer, iov.iov_len)) {
ret = bdrv_co_do_write_zeroes(bs, cluster_sector_num,
cluster_nb_sectors, 0);
} else {
/* This does not change the data on the disk, it is not necessary
* to flush even in cache=writethrough mode.
*/
ret = drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors,
&bounce_qiov);
}
if (ret < 0) {
/* It might be okay to ignore write errors for guest requests. If this
* is a deliberate copy-on-read then we don't want to ignore the error.
* Simply report it in all cases.
*/
goto err;
}
skip_bytes = (sector_num - cluster_sector_num) * BDRV_SECTOR_SIZE;
qemu_iovec_from_buf(qiov, 0, bounce_buffer + skip_bytes,
nb_sectors * BDRV_SECTOR_SIZE);
err:
qemu_vfree(bounce_buffer);
return ret;
}
/*
* Forwards an already correctly aligned request to the BlockDriver. This
* handles copy on read and zeroing after EOF; any other features must be
* implemented by the caller.
*/
static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
int64_t align, QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
int ret;
int64_t sector_num = offset >> BDRV_SECTOR_BITS;
unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
assert(!qiov || bytes == qiov->size);
/* Handle Copy on Read and associated serialisation */
if (flags & BDRV_REQ_COPY_ON_READ) {
/* If we touch the same cluster it counts as an overlap. This
* guarantees that allocating writes will be serialized and not race
* with each other for the same cluster. For example, in copy-on-read
* it ensures that the CoR read and write operations are atomic and
* guest writes cannot interleave between them. */
mark_request_serialising(req, bdrv_get_cluster_size(bs));
}
wait_serialising_requests(req);
if (flags & BDRV_REQ_COPY_ON_READ) {
int pnum;
ret = bdrv_is_allocated(bs, sector_num, nb_sectors, &pnum);
if (ret < 0) {
goto out;
}
if (!ret || pnum != nb_sectors) {
ret = bdrv_co_do_copy_on_readv(bs, sector_num, nb_sectors, qiov);
goto out;
}
}
/* Forward the request to the BlockDriver */
if (!bs->zero_beyond_eof) {
ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
} else {
/* Read zeros after EOF */
int64_t total_sectors, max_nb_sectors;
total_sectors = bdrv_nb_sectors(bs);
if (total_sectors < 0) {
ret = total_sectors;
goto out;
}
max_nb_sectors = ROUND_UP(MAX(0, total_sectors - sector_num),
align >> BDRV_SECTOR_BITS);
if (nb_sectors < max_nb_sectors) {
ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
} else if (max_nb_sectors > 0) {
QEMUIOVector local_qiov;
qemu_iovec_init(&local_qiov, qiov->niov);
qemu_iovec_concat(&local_qiov, qiov, 0,
max_nb_sectors * BDRV_SECTOR_SIZE);
ret = drv->bdrv_co_readv(bs, sector_num, max_nb_sectors,
&local_qiov);
qemu_iovec_destroy(&local_qiov);
} else {
ret = 0;
}
/* Reading beyond end of file is supposed to produce zeroes */
if (ret == 0 && total_sectors < sector_num + nb_sectors) {
uint64_t offset = MAX(0, total_sectors - sector_num);
uint64_t bytes = (sector_num + nb_sectors - offset) *
BDRV_SECTOR_SIZE;
qemu_iovec_memset(qiov, offset * BDRV_SECTOR_SIZE, 0, bytes);
}
}
out:
return ret;
}
/*
* Handle a read request in coroutine context
*/
static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BlockDriver *drv = bs->drv;
BdrvTrackedRequest req;
/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
uint8_t *head_buf = NULL;
uint8_t *tail_buf = NULL;
QEMUIOVector local_qiov;
bool use_local_qiov = false;
int ret;
if (!drv) {
return -ENOMEDIUM;
}
ret = bdrv_check_byte_request(bs, offset, bytes);
if (ret < 0) {
return ret;
}
/* Don't do copy-on-read if we read data before write operation */
if (bs->copy_on_read && !(flags & BDRV_REQ_NO_COPY_ON_READ)) {
flags |= BDRV_REQ_COPY_ON_READ;
}
/* throttling disk I/O */
if (bs->io_limits_enabled) {
throttle_group_co_io_limits_intercept(bs, bytes, false);
}
/* Align read if necessary by padding qiov */
if (offset & (align - 1)) {
head_buf = qemu_blockalign(bs, align);
qemu_iovec_init(&local_qiov, qiov->niov + 2);
qemu_iovec_add(&local_qiov, head_buf, offset & (align - 1));
qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
use_local_qiov = true;
bytes += offset & (align - 1);
offset = offset & ~(align - 1);
}
if ((offset + bytes) & (align - 1)) {
if (!use_local_qiov) {
qemu_iovec_init(&local_qiov, qiov->niov + 1);
qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
use_local_qiov = true;
}
tail_buf = qemu_blockalign(bs, align);
qemu_iovec_add(&local_qiov, tail_buf,
align - ((offset + bytes) & (align - 1)));
bytes = ROUND_UP(bytes, align);
}
tracked_request_begin(&req, bs, offset, bytes, false);
ret = bdrv_aligned_preadv(bs, &req, offset, bytes, align,
use_local_qiov ? &local_qiov : qiov,
flags);
tracked_request_end(&req);
if (use_local_qiov) {
qemu_iovec_destroy(&local_qiov);
qemu_vfree(head_buf);
qemu_vfree(tail_buf);
}
return ret;
}
static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return -EINVAL;
}
return bdrv_co_do_preadv(bs, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
}
int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_readv(bs, sector_num, nb_sectors);
return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov, 0);
}
int coroutine_fn bdrv_co_no_copy_on_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_no_copy_on_readv(bs, sector_num, nb_sectors);
return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov,
BDRV_REQ_NO_COPY_ON_READ);
}
int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_copy_on_readv(bs, sector_num, nb_sectors);
return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov,
BDRV_REQ_COPY_ON_READ);
}
#define MAX_WRITE_ZEROES_BOUNCE_BUFFER 32768
static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
{
BlockDriver *drv = bs->drv;
QEMUIOVector qiov;
struct iovec iov = {0};
int ret = 0;
int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_write_zeroes,
BDRV_REQUEST_MAX_SECTORS);
while (nb_sectors > 0 && !ret) {
int num = nb_sectors;
/* Align request. Block drivers can expect the "bulk" of the request
* to be aligned.
*/
if (bs->bl.write_zeroes_alignment
&& num > bs->bl.write_zeroes_alignment) {
if (sector_num % bs->bl.write_zeroes_alignment != 0) {
/* Make a small request up to the first aligned sector. */
num = bs->bl.write_zeroes_alignment;
num -= sector_num % bs->bl.write_zeroes_alignment;
} else if ((sector_num + num) % bs->bl.write_zeroes_alignment != 0) {
/* Shorten the request to the last aligned sector. num cannot
* underflow because num > bs->bl.write_zeroes_alignment.
*/
num -= (sector_num + num) % bs->bl.write_zeroes_alignment;
}
}
/* limit request size */
if (num > max_write_zeroes) {
num = max_write_zeroes;
}
ret = -ENOTSUP;
/* First try the efficient write zeroes operation */
if (drv->bdrv_co_write_zeroes) {
ret = drv->bdrv_co_write_zeroes(bs, sector_num, num, flags);
}
if (ret == -ENOTSUP) {
/* Fall back to bounce buffer if write zeroes is unsupported */
int max_xfer_len = MIN_NON_ZERO(bs->bl.max_transfer_length,
MAX_WRITE_ZEROES_BOUNCE_BUFFER);
num = MIN(num, max_xfer_len);
iov.iov_len = num * BDRV_SECTOR_SIZE;
if (iov.iov_base == NULL) {
iov.iov_base = qemu_try_blockalign(bs, num * BDRV_SECTOR_SIZE);
if (iov.iov_base == NULL) {
ret = -ENOMEM;
goto fail;
}
memset(iov.iov_base, 0, num * BDRV_SECTOR_SIZE);
}
qemu_iovec_init_external(&qiov, &iov, 1);
ret = drv->bdrv_co_writev(bs, sector_num, num, &qiov);
/* Keep bounce buffer around if it is big enough for all
* all future requests.
*/
if (num < max_xfer_len) {
qemu_vfree(iov.iov_base);
iov.iov_base = NULL;
}
}
sector_num += num;
nb_sectors -= num;
}
fail:
qemu_vfree(iov.iov_base);
return ret;
}
/*
* Forwards an already correctly aligned write request to the BlockDriver.
*/
static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
bool waited;
int ret;
int64_t sector_num = offset >> BDRV_SECTOR_BITS;
unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
assert(!qiov || bytes == qiov->size);
waited = wait_serialising_requests(req);
assert(!waited || !req->serialising);
assert(req->overlap_offset <= offset);
assert(offset + bytes <= req->overlap_offset + req->overlap_bytes);
ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);
if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
!(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_write_zeroes &&
qemu_iovec_is_zero(qiov)) {
flags |= BDRV_REQ_ZERO_WRITE;
if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) {
flags |= BDRV_REQ_MAY_UNMAP;
}
}
if (ret < 0) {
/* Do nothing, write notifier decided to fail this request */
} else if (flags & BDRV_REQ_ZERO_WRITE) {
bdrv_debug_event(bs, BLKDBG_PWRITEV_ZERO);
ret = bdrv_co_do_write_zeroes(bs, sector_num, nb_sectors, flags);
} else {
bdrv_debug_event(bs, BLKDBG_PWRITEV);
ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_DONE);
if (ret == 0 && !bs->enable_write_cache) {
ret = bdrv_co_flush(bs);
}
bdrv_set_dirty(bs, sector_num, nb_sectors);
if (bs->wr_highest_offset < offset + bytes) {
bs->wr_highest_offset = offset + bytes;
}
if (ret >= 0) {
bs->total_sectors = MAX(bs->total_sectors, sector_num + nb_sectors);
}
return ret;
}
static int coroutine_fn bdrv_co_do_zero_pwritev(BlockDriverState *bs,
int64_t offset,
unsigned int bytes,
BdrvRequestFlags flags,
BdrvTrackedRequest *req)
{
uint8_t *buf = NULL;
QEMUIOVector local_qiov;
struct iovec iov;
uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
unsigned int head_padding_bytes, tail_padding_bytes;
int ret = 0;
head_padding_bytes = offset & (align - 1);
tail_padding_bytes = align - ((offset + bytes) & (align - 1));
assert(flags & BDRV_REQ_ZERO_WRITE);
if (head_padding_bytes || tail_padding_bytes) {
buf = qemu_blockalign(bs, align);
iov = (struct iovec) {
.iov_base = buf,
.iov_len = align,
};
qemu_iovec_init_external(&local_qiov, &iov, 1);
}
if (head_padding_bytes) {
uint64_t zero_bytes = MIN(bytes, align - head_padding_bytes);
/* RMW the unaligned part before head. */
mark_request_serialising(req, align);
wait_serialising_requests(req);
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD);
ret = bdrv_aligned_preadv(bs, req, offset & ~(align - 1), align,
align, &local_qiov, 0);
if (ret < 0) {
goto fail;
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD);
memset(buf + head_padding_bytes, 0, zero_bytes);
ret = bdrv_aligned_pwritev(bs, req, offset & ~(align - 1), align,
&local_qiov,
flags & ~BDRV_REQ_ZERO_WRITE);
if (ret < 0) {
goto fail;
}
offset += zero_bytes;
bytes -= zero_bytes;
}
assert(!bytes || (offset & (align - 1)) == 0);
if (bytes >= align) {
/* Write the aligned part in the middle. */
uint64_t aligned_bytes = bytes & ~(align - 1);
ret = bdrv_aligned_pwritev(bs, req, offset, aligned_bytes,
NULL, flags);
if (ret < 0) {
goto fail;
}
bytes -= aligned_bytes;
offset += aligned_bytes;
}
assert(!bytes || (offset & (align - 1)) == 0);
if (bytes) {
assert(align == tail_padding_bytes + bytes);
/* RMW the unaligned part after tail. */
mark_request_serialising(req, align);
wait_serialising_requests(req);
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
ret = bdrv_aligned_preadv(bs, req, offset, align,
align, &local_qiov, 0);
if (ret < 0) {
goto fail;
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);
memset(buf, 0, bytes);
ret = bdrv_aligned_pwritev(bs, req, offset, align,
&local_qiov, flags & ~BDRV_REQ_ZERO_WRITE);
}
fail:
qemu_vfree(buf);
return ret;
}
/*
* Handle a write request in coroutine context
*/
static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BdrvTrackedRequest req;
/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
uint8_t *head_buf = NULL;
uint8_t *tail_buf = NULL;
QEMUIOVector local_qiov;
bool use_local_qiov = false;
int ret;
if (!bs->drv) {
return -ENOMEDIUM;
}
if (bs->read_only) {
return -EPERM;
}
ret = bdrv_check_byte_request(bs, offset, bytes);
if (ret < 0) {
return ret;
}
/* throttling disk I/O */
if (bs->io_limits_enabled) {
throttle_group_co_io_limits_intercept(bs, bytes, true);
}
/*
* Align write if necessary by performing a read-modify-write cycle.
* Pad qiov with the read parts and be sure to have a tracked request not
* only for bdrv_aligned_pwritev, but also for the reads of the RMW cycle.
*/
tracked_request_begin(&req, bs, offset, bytes, true);
if (!qiov) {
ret = bdrv_co_do_zero_pwritev(bs, offset, bytes, flags, &req);
goto out;
}
if (offset & (align - 1)) {
QEMUIOVector head_qiov;
struct iovec head_iov;
mark_request_serialising(&req, align);
wait_serialising_requests(&req);
head_buf = qemu_blockalign(bs, align);
head_iov = (struct iovec) {
.iov_base = head_buf,
.iov_len = align,
};
qemu_iovec_init_external(&head_qiov, &head_iov, 1);
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD);
ret = bdrv_aligned_preadv(bs, &req, offset & ~(align - 1), align,
align, &head_qiov, 0);
if (ret < 0) {
goto fail;
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD);
qemu_iovec_init(&local_qiov, qiov->niov + 2);
qemu_iovec_add(&local_qiov, head_buf, offset & (align - 1));
qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
use_local_qiov = true;
bytes += offset & (align - 1);
offset = offset & ~(align - 1);
}
if ((offset + bytes) & (align - 1)) {
QEMUIOVector tail_qiov;
struct iovec tail_iov;
size_t tail_bytes;
bool waited;
mark_request_serialising(&req, align);
waited = wait_serialising_requests(&req);
assert(!waited || !use_local_qiov);
tail_buf = qemu_blockalign(bs, align);
tail_iov = (struct iovec) {
.iov_base = tail_buf,
.iov_len = align,
};
qemu_iovec_init_external(&tail_qiov, &tail_iov, 1);
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
ret = bdrv_aligned_preadv(bs, &req, (offset + bytes) & ~(align - 1), align,
align, &tail_qiov, 0);
if (ret < 0) {
goto fail;
}
bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL);
if (!use_local_qiov) {
qemu_iovec_init(&local_qiov, qiov->niov + 1);
qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
use_local_qiov = true;
}
tail_bytes = (offset + bytes) & (align - 1);
qemu_iovec_add(&local_qiov, tail_buf + tail_bytes, align - tail_bytes);
bytes = ROUND_UP(bytes, align);
}
ret = bdrv_aligned_pwritev(bs, &req, offset, bytes,
use_local_qiov ? &local_qiov : qiov,
flags);
fail:
if (use_local_qiov) {
qemu_iovec_destroy(&local_qiov);
}
qemu_vfree(head_buf);
qemu_vfree(tail_buf);
out:
tracked_request_end(&req);
return ret;
}
static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return -EINVAL;
}
return bdrv_co_do_pwritev(bs, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
}
int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
trace_bdrv_co_writev(bs, sector_num, nb_sectors);
return bdrv_co_do_writev(bs, sector_num, nb_sectors, qiov, 0);
}
int coroutine_fn bdrv_co_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
BdrvRequestFlags flags)
{
trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors, flags);
if (!(bs->open_flags & BDRV_O_UNMAP)) {
flags &= ~BDRV_REQ_MAY_UNMAP;
}
return bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
BDRV_REQ_ZERO_WRITE | flags);
}
int bdrv_flush_all(void)
{
BlockDriverState *bs = NULL;
int result = 0;
while ((bs = bdrv_next(bs))) {
AioContext *aio_context = bdrv_get_aio_context(bs);
int ret;
aio_context_acquire(aio_context);
ret = bdrv_flush(bs);
if (ret < 0 && !result) {
result = ret;
}
aio_context_release(aio_context);
}
return result;
}
typedef struct BdrvCoGetBlockStatusData {
BlockDriverState *bs;
BlockDriverState *base;
int64_t sector_num;
int nb_sectors;
int *pnum;
int64_t ret;
bool done;
} BdrvCoGetBlockStatusData;
/*
* Returns the allocation status of the specified sectors.
* Drivers not implementing the functionality are assumed to not support
* backing files, hence all their sectors are reported as allocated.
*
* If 'sector_num' is beyond the end of the disk image the return value is 0
* and 'pnum' is set to 0.
*
* 'pnum' is set to the number of sectors (including and immediately following
* the specified sector) that are known to be in the same
* allocated/unallocated state.
*
* 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes
* beyond the end of the disk image it will be clamped.
*/
static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum)
{
int64_t total_sectors;
int64_t n;
int64_t ret, ret2;
total_sectors = bdrv_nb_sectors(bs);
if (total_sectors < 0) {
return total_sectors;
}
if (sector_num >= total_sectors) {
*pnum = 0;
return 0;
}
n = total_sectors - sector_num;
if (n < nb_sectors) {
nb_sectors = n;
}
if (!bs->drv->bdrv_co_get_block_status) {
*pnum = nb_sectors;
ret = BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED;
if (bs->drv->protocol_name) {
ret |= BDRV_BLOCK_OFFSET_VALID | (sector_num * BDRV_SECTOR_SIZE);
}
return ret;
}
ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum);
if (ret < 0) {
*pnum = 0;
return ret;
}
if (ret & BDRV_BLOCK_RAW) {
assert(ret & BDRV_BLOCK_OFFSET_VALID);
return bdrv_get_block_status(bs->file->bs, ret >> BDRV_SECTOR_BITS,
*pnum, pnum);
}
if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
ret |= BDRV_BLOCK_ALLOCATED;
} else {
if (bdrv_unallocated_blocks_are_zero(bs)) {
ret |= BDRV_BLOCK_ZERO;
} else if (bs->backing) {
BlockDriverState *bs2 = bs->backing->bs;
int64_t nb_sectors2 = bdrv_nb_sectors(bs2);
if (nb_sectors2 >= 0 && sector_num >= nb_sectors2) {
ret |= BDRV_BLOCK_ZERO;
}
}
}
if (bs->file &&
(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
(ret & BDRV_BLOCK_OFFSET_VALID)) {
int file_pnum;
ret2 = bdrv_co_get_block_status(bs->file->bs, ret >> BDRV_SECTOR_BITS,
*pnum, &file_pnum);
if (ret2 >= 0) {
/* Ignore errors. This is just providing extra information, it
* is useful but not necessary.
*/
if (!file_pnum) {
/* !file_pnum indicates an offset at or beyond the EOF; it is
* perfectly valid for the format block driver to point to such
* offsets, so catch it and mark everything as zero */
ret |= BDRV_BLOCK_ZERO;
} else {
/* Limit request to the range reported by the protocol driver */
*pnum = file_pnum;
ret |= (ret2 & BDRV_BLOCK_ZERO);
}
}
}
return ret;
}
static int64_t coroutine_fn bdrv_co_get_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors,
int *pnum)
{
BlockDriverState *p;
int64_t ret = 0;
assert(bs != base);
for (p = bs; p != base; p = backing_bs(p)) {
ret = bdrv_co_get_block_status(p, sector_num, nb_sectors, pnum);
if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) {
break;
}
/* [sector_num, pnum] unallocated on this layer, which could be only
* the first part of [sector_num, nb_sectors]. */
nb_sectors = MIN(nb_sectors, *pnum);
}
return ret;
}
/* Coroutine wrapper for bdrv_get_block_status_above() */
static void coroutine_fn bdrv_get_block_status_above_co_entry(void *opaque)
{
BdrvCoGetBlockStatusData *data = opaque;
data->ret = bdrv_co_get_block_status_above(data->bs, data->base,
data->sector_num,
data->nb_sectors,
data->pnum);
data->done = true;
}
/*
* Synchronous wrapper around bdrv_co_get_block_status_above().
*
* See bdrv_co_get_block_status_above() for details.
*/
int64_t bdrv_get_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors, int *pnum)
{
Coroutine *co;
BdrvCoGetBlockStatusData data = {
.bs = bs,
.base = base,
.sector_num = sector_num,
.nb_sectors = nb_sectors,
.pnum = pnum,
.done = false,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_get_block_status_above_co_entry(&data);
} else {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_get_block_status_above_co_entry);
qemu_coroutine_enter(co, &data);
while (!data.done) {
aio_poll(aio_context, true);
}
}
return data.ret;
}
int64_t bdrv_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum)
{
return bdrv_get_block_status_above(bs, backing_bs(bs),
sector_num, nb_sectors, pnum);
}
int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum);
if (ret < 0) {
return ret;
}
return !!(ret & BDRV_BLOCK_ALLOCATED);
}
/*
* Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP]
*
* Return true if the given sector is allocated in any image between
* BASE and TOP (inclusive). BASE can be NULL to check if the given
* sector is allocated in any image of the chain. Return false otherwise.
*
* 'pnum' is set to the number of sectors (including and immediately following
* the specified sector) that are known to be in the same
* allocated/unallocated state.
*
*/
int bdrv_is_allocated_above(BlockDriverState *top,
BlockDriverState *base,
int64_t sector_num,
int nb_sectors, int *pnum)
{
BlockDriverState *intermediate;
int ret, n = nb_sectors;
intermediate = top;
while (intermediate && intermediate != base) {
int pnum_inter;
ret = bdrv_is_allocated(intermediate, sector_num, nb_sectors,
&pnum_inter);
if (ret < 0) {
return ret;
} else if (ret) {
*pnum = pnum_inter;
return 1;
}
/*
* [sector_num, nb_sectors] is unallocated on top but intermediate
* might have
*
* [sector_num+x, nr_sectors] allocated.
*/
if (n > pnum_inter &&
(intermediate == top ||
sector_num + pnum_inter < intermediate->total_sectors)) {
n = pnum_inter;
}
intermediate = backing_bs(intermediate);
}
*pnum = n;
return 0;
}
int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BlockDriver *drv = bs->drv;
int ret;
if (!drv) {
return -ENOMEDIUM;
}
if (!drv->bdrv_write_compressed) {
return -ENOTSUP;
}
ret = bdrv_check_request(bs, sector_num, nb_sectors);
if (ret < 0) {
return ret;
}
assert(QLIST_EMPTY(&bs->dirty_bitmaps));
return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors);
}
int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
int64_t pos, int size)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *) buf,
.iov_len = size,
};
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_writev_vmstate(bs, &qiov, pos);
}
int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
{
BlockDriver *drv = bs->drv;
if (!drv) {
return -ENOMEDIUM;
} else if (drv->bdrv_save_vmstate) {
return drv->bdrv_save_vmstate(bs, qiov, pos);
} else if (bs->file) {
return bdrv_writev_vmstate(bs->file->bs, qiov, pos);
}
return -ENOTSUP;
}
int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
int64_t pos, int size)
{
BlockDriver *drv = bs->drv;
if (!drv)
return -ENOMEDIUM;
if (drv->bdrv_load_vmstate)
return drv->bdrv_load_vmstate(bs, buf, pos, size);
if (bs->file)
return bdrv_load_vmstate(bs->file->bs, buf, pos, size);
return -ENOTSUP;
}
/**************************************************************/
/* async I/Os */
BlockAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_readv(bs, sector_num, nb_sectors, opaque);
return bdrv_co_aio_rw_vector(bs, sector_num, qiov, nb_sectors, 0,
cb, opaque, false);
}
BlockAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_writev(bs, sector_num, nb_sectors, opaque);
return bdrv_co_aio_rw_vector(bs, sector_num, qiov, nb_sectors, 0,
cb, opaque, true);
}
BlockAIOCB *bdrv_aio_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_write_zeroes(bs, sector_num, nb_sectors, flags, opaque);
return bdrv_co_aio_rw_vector(bs, sector_num, NULL, nb_sectors,
BDRV_REQ_ZERO_WRITE | flags,
cb, opaque, true);
}
typedef struct MultiwriteCB {
int error;
int num_requests;
int num_callbacks;
struct {
BlockCompletionFunc *cb;
void *opaque;
QEMUIOVector *free_qiov;
} callbacks[];
} MultiwriteCB;
static void multiwrite_user_cb(MultiwriteCB *mcb)
{
int i;
for (i = 0; i < mcb->num_callbacks; i++) {
mcb->callbacks[i].cb(mcb->callbacks[i].opaque, mcb->error);
if (mcb->callbacks[i].free_qiov) {
qemu_iovec_destroy(mcb->callbacks[i].free_qiov);
}
g_free(mcb->callbacks[i].free_qiov);
}
}
static void multiwrite_cb(void *opaque, int ret)
{
MultiwriteCB *mcb = opaque;
trace_multiwrite_cb(mcb, ret);
if (ret < 0 && !mcb->error) {
mcb->error = ret;
}
mcb->num_requests--;
if (mcb->num_requests == 0) {
multiwrite_user_cb(mcb);
g_free(mcb);
}
}
static int multiwrite_req_compare(const void *a, const void *b)
{
const BlockRequest *req1 = a, *req2 = b;
/*
* Note that we can't simply subtract req2->sector from req1->sector
* here as that could overflow the return value.
*/
if (req1->sector > req2->sector) {
return 1;
} else if (req1->sector < req2->sector) {
return -1;
} else {
return 0;
}
}
/*
* Takes a bunch of requests and tries to merge them. Returns the number of
* requests that remain after merging.
*/
static int multiwrite_merge(BlockDriverState *bs, BlockRequest *reqs,
int num_reqs, MultiwriteCB *mcb)
{
int i, outidx;
// Sort requests by start sector
qsort(reqs, num_reqs, sizeof(*reqs), &multiwrite_req_compare);
// Check if adjacent requests touch the same clusters. If so, combine them,
// filling up gaps with zero sectors.
outidx = 0;
for (i = 1; i < num_reqs; i++) {
int merge = 0;
int64_t oldreq_last = reqs[outidx].sector + reqs[outidx].nb_sectors;
// Handle exactly sequential writes and overlapping writes.
if (reqs[i].sector <= oldreq_last) {
merge = 1;
}
if (reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1 > IOV_MAX) {
merge = 0;
}
if (bs->bl.max_transfer_length && reqs[outidx].nb_sectors +
reqs[i].nb_sectors > bs->bl.max_transfer_length) {
merge = 0;
}
if (merge) {
size_t size;
QEMUIOVector *qiov = g_malloc0(sizeof(*qiov));
qemu_iovec_init(qiov,
reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1);
// Add the first request to the merged one. If the requests are
// overlapping, drop the last sectors of the first request.
size = (reqs[i].sector - reqs[outidx].sector) << 9;
qemu_iovec_concat(qiov, reqs[outidx].qiov, 0, size);
// We should need to add any zeros between the two requests
assert (reqs[i].sector <= oldreq_last);
// Add the second request
qemu_iovec_concat(qiov, reqs[i].qiov, 0, reqs[i].qiov->size);
// Add tail of first request, if necessary
if (qiov->size < reqs[outidx].qiov->size) {
qemu_iovec_concat(qiov, reqs[outidx].qiov, qiov->size,
reqs[outidx].qiov->size - qiov->size);
}
reqs[outidx].nb_sectors = qiov->size >> 9;
reqs[outidx].qiov = qiov;
mcb->callbacks[i].free_qiov = reqs[outidx].qiov;
} else {
outidx++;
reqs[outidx].sector = reqs[i].sector;
reqs[outidx].nb_sectors = reqs[i].nb_sectors;
reqs[outidx].qiov = reqs[i].qiov;
}
}
if (bs->blk) {
block_acct_merge_done(blk_get_stats(bs->blk), BLOCK_ACCT_WRITE,
num_reqs - outidx - 1);
}
return outidx + 1;
}
/*
* Submit multiple AIO write requests at once.
*
* On success, the function returns 0 and all requests in the reqs array have
* been submitted. In error case this function returns -1, and any of the
* requests may or may not be submitted yet. In particular, this means that the
* callback will be called for some of the requests, for others it won't. The
* caller must check the error field of the BlockRequest to wait for the right
* callbacks (if error != 0, no callback will be called).
*
* The implementation may modify the contents of the reqs array, e.g. to merge
* requests. However, the fields opaque and error are left unmodified as they
* are used to signal failure for a single request to the caller.
*/
int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs)
{
MultiwriteCB *mcb;
int i;
/* don't submit writes if we don't have a medium */
if (bs->drv == NULL) {
for (i = 0; i < num_reqs; i++) {
reqs[i].error = -ENOMEDIUM;
}
return -1;
}
if (num_reqs == 0) {
return 0;
}
// Create MultiwriteCB structure
mcb = g_malloc0(sizeof(*mcb) + num_reqs * sizeof(*mcb->callbacks));
mcb->num_requests = 0;
mcb->num_callbacks = num_reqs;
for (i = 0; i < num_reqs; i++) {
mcb->callbacks[i].cb = reqs[i].cb;
mcb->callbacks[i].opaque = reqs[i].opaque;
}
// Check for mergable requests
num_reqs = multiwrite_merge(bs, reqs, num_reqs, mcb);
trace_bdrv_aio_multiwrite(mcb, mcb->num_callbacks, num_reqs);
/* Run the aio requests. */
mcb->num_requests = num_reqs;
for (i = 0; i < num_reqs; i++) {
bdrv_co_aio_rw_vector(bs, reqs[i].sector, reqs[i].qiov,
reqs[i].nb_sectors, reqs[i].flags,
multiwrite_cb, mcb,
true);
}
return 0;
}
void bdrv_aio_cancel(BlockAIOCB *acb)
{
qemu_aio_ref(acb);
bdrv_aio_cancel_async(acb);
while (acb->refcnt > 1) {
if (acb->aiocb_info->get_aio_context) {
aio_poll(acb->aiocb_info->get_aio_context(acb), true);
} else if (acb->bs) {
aio_poll(bdrv_get_aio_context(acb->bs), true);
} else {
abort();
}
}
qemu_aio_unref(acb);
}
/* Async version of aio cancel. The caller is not blocked if the acb implements
* cancel_async, otherwise we do nothing and let the request normally complete.
* In either case the completion callback must be called. */
void bdrv_aio_cancel_async(BlockAIOCB *acb)
{
if (acb->aiocb_info->cancel_async) {
acb->aiocb_info->cancel_async(acb);
}
}
/**************************************************************/
/* async block device emulation */
typedef struct BlockAIOCBSync {
BlockAIOCB common;
QEMUBH *bh;
int ret;
/* vector translation state */
QEMUIOVector *qiov;
uint8_t *bounce;
int is_write;
} BlockAIOCBSync;
static const AIOCBInfo bdrv_em_aiocb_info = {
.aiocb_size = sizeof(BlockAIOCBSync),
};
static void bdrv_aio_bh_cb(void *opaque)
{
BlockAIOCBSync *acb = opaque;
if (!acb->is_write && acb->ret >= 0) {
qemu_iovec_from_buf(acb->qiov, 0, acb->bounce, acb->qiov->size);
}
qemu_vfree(acb->bounce);
acb->common.cb(acb->common.opaque, acb->ret);
qemu_bh_delete(acb->bh);
acb->bh = NULL;
qemu_aio_unref(acb);
}
static BlockAIOCB *bdrv_aio_rw_vector(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
BlockCompletionFunc *cb,
void *opaque,
int is_write)
{
BlockAIOCBSync *acb;
acb = qemu_aio_get(&bdrv_em_aiocb_info, bs, cb, opaque);
acb->is_write = is_write;
acb->qiov = qiov;
acb->bounce = qemu_try_blockalign(bs, qiov->size);
acb->bh = aio_bh_new(bdrv_get_aio_context(bs), bdrv_aio_bh_cb, acb);
if (acb->bounce == NULL) {
acb->ret = -ENOMEM;
} else if (is_write) {
qemu_iovec_to_buf(acb->qiov, 0, acb->bounce, qiov->size);
acb->ret = bs->drv->bdrv_write(bs, sector_num, acb->bounce, nb_sectors);
} else {
acb->ret = bs->drv->bdrv_read(bs, sector_num, acb->bounce, nb_sectors);
}
qemu_bh_schedule(acb->bh);
return &acb->common;
}
static BlockAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
return bdrv_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
}
static BlockAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
return bdrv_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
}
typedef struct BlockAIOCBCoroutine {
BlockAIOCB common;
BlockRequest req;
bool is_write;
bool need_bh;
bool *done;
QEMUBH* bh;
} BlockAIOCBCoroutine;
static const AIOCBInfo bdrv_em_co_aiocb_info = {
.aiocb_size = sizeof(BlockAIOCBCoroutine),
};
static void bdrv_co_complete(BlockAIOCBCoroutine *acb)
{
if (!acb->need_bh) {
acb->common.cb(acb->common.opaque, acb->req.error);
qemu_aio_unref(acb);
}
}
static void bdrv_co_em_bh(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
assert(!acb->need_bh);
qemu_bh_delete(acb->bh);
bdrv_co_complete(acb);
}
static void bdrv_co_maybe_schedule_bh(BlockAIOCBCoroutine *acb)
{
acb->need_bh = false;
if (acb->req.error != -EINPROGRESS) {
BlockDriverState *bs = acb->common.bs;
acb->bh = aio_bh_new(bdrv_get_aio_context(bs), bdrv_co_em_bh, acb);
qemu_bh_schedule(acb->bh);
}
}
/* Invoke bdrv_co_do_readv/bdrv_co_do_writev */
static void coroutine_fn bdrv_co_do_rw(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
BlockDriverState *bs = acb->common.bs;
if (!acb->is_write) {
acb->req.error = bdrv_co_do_readv(bs, acb->req.sector,
acb->req.nb_sectors, acb->req.qiov, acb->req.flags);
} else {
acb->req.error = bdrv_co_do_writev(bs, acb->req.sector,
acb->req.nb_sectors, acb->req.qiov, acb->req.flags);
}
bdrv_co_complete(acb);
}
static BlockAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
BdrvRequestFlags flags,
BlockCompletionFunc *cb,
void *opaque,
bool is_write)
{
Coroutine *co;
BlockAIOCBCoroutine *acb;
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
acb->req.sector = sector_num;
acb->req.nb_sectors = nb_sectors;
acb->req.qiov = qiov;
acb->req.flags = flags;
acb->is_write = is_write;
co = qemu_coroutine_create(bdrv_co_do_rw);
qemu_coroutine_enter(co, acb);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
}
static void coroutine_fn bdrv_aio_flush_co_entry(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
BlockDriverState *bs = acb->common.bs;
acb->req.error = bdrv_co_flush(bs);
bdrv_co_complete(acb);
}
BlockAIOCB *bdrv_aio_flush(BlockDriverState *bs,
BlockCompletionFunc *cb, void *opaque)
{
trace_bdrv_aio_flush(bs, opaque);
Coroutine *co;
BlockAIOCBCoroutine *acb;
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
co = qemu_coroutine_create(bdrv_aio_flush_co_entry);
qemu_coroutine_enter(co, acb);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
}
static void coroutine_fn bdrv_aio_discard_co_entry(void *opaque)
{
BlockAIOCBCoroutine *acb = opaque;
BlockDriverState *bs = acb->common.bs;
acb->req.error = bdrv_co_discard(bs, acb->req.sector, acb->req.nb_sectors);
bdrv_co_complete(acb);
}
BlockAIOCB *bdrv_aio_discard(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
BlockCompletionFunc *cb, void *opaque)
{
Coroutine *co;
BlockAIOCBCoroutine *acb;
trace_bdrv_aio_discard(bs, sector_num, nb_sectors, opaque);
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
acb->req.sector = sector_num;
acb->req.nb_sectors = nb_sectors;
co = qemu_coroutine_create(bdrv_aio_discard_co_entry);
qemu_coroutine_enter(co, acb);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
}
void *qemu_aio_get(const AIOCBInfo *aiocb_info, BlockDriverState *bs,
BlockCompletionFunc *cb, void *opaque)
{
BlockAIOCB *acb;
acb = g_malloc(aiocb_info->aiocb_size);
acb->aiocb_info = aiocb_info;
acb->bs = bs;
acb->cb = cb;
acb->opaque = opaque;
acb->refcnt = 1;
return acb;
}
void qemu_aio_ref(void *p)
{
BlockAIOCB *acb = p;
acb->refcnt++;
}
void qemu_aio_unref(void *p)
{
BlockAIOCB *acb = p;
assert(acb->refcnt > 0);
if (--acb->refcnt == 0) {
g_free(acb);
}
}
/**************************************************************/
/* Coroutine block device emulation */
typedef struct CoroutineIOCompletion {
Coroutine *coroutine;
int ret;
} CoroutineIOCompletion;
static void bdrv_co_io_em_complete(void *opaque, int ret)
{
CoroutineIOCompletion *co = opaque;
co->ret = ret;
qemu_coroutine_enter(co->coroutine, NULL);
}
static int coroutine_fn bdrv_co_io_em(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *iov,
bool is_write)
{
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
BlockAIOCB *acb;
if (is_write) {
acb = bs->drv->bdrv_aio_writev(bs, sector_num, iov, nb_sectors,
bdrv_co_io_em_complete, &co);
} else {
acb = bs->drv->bdrv_aio_readv(bs, sector_num, iov, nb_sectors,
bdrv_co_io_em_complete, &co);
}
trace_bdrv_co_io_em(bs, sector_num, nb_sectors, is_write, acb);
if (!acb) {
return -EIO;
}
qemu_coroutine_yield();
return co.ret;
}
static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov)
{
return bdrv_co_io_em(bs, sector_num, nb_sectors, iov, false);
}
static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov)
{
return bdrv_co_io_em(bs, sector_num, nb_sectors, iov, true);
}
static void coroutine_fn bdrv_flush_co_entry(void *opaque)
{
RwCo *rwco = opaque;
rwco->ret = bdrv_co_flush(rwco->bs);
}
int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
{
int ret;
if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
bdrv_is_sg(bs)) {
return 0;
}
/* Write back cached data to the OS even with cache=unsafe */
BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_OS);
if (bs->drv->bdrv_co_flush_to_os) {
ret = bs->drv->bdrv_co_flush_to_os(bs);
if (ret < 0) {
return ret;
}
}
/* But don't actually force it to the disk with cache=unsafe */
if (bs->open_flags & BDRV_O_NO_FLUSH) {
goto flush_parent;
}
BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
if (bs->drv->bdrv_co_flush_to_disk) {
ret = bs->drv->bdrv_co_flush_to_disk(bs);
} else if (bs->drv->bdrv_aio_flush) {
BlockAIOCB *acb;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
acb = bs->drv->bdrv_aio_flush(bs, bdrv_co_io_em_complete, &co);
if (acb == NULL) {
ret = -EIO;
} else {
qemu_coroutine_yield();
ret = co.ret;
}
} else {
/*
* Some block drivers always operate in either writethrough or unsafe
* mode and don't support bdrv_flush therefore. Usually qemu doesn't
* know how the server works (because the behaviour is hardcoded or
* depends on server-side configuration), so we can't ensure that
* everything is safe on disk. Returning an error doesn't work because
* that would break guests even if the server operates in writethrough
* mode.
*
* Let's hope the user knows what he's doing.
*/
ret = 0;
}
if (ret < 0) {
return ret;
}
/* Now flush the underlying protocol. It will also have BDRV_O_NO_FLUSH
* in the case of cache=unsafe, so there are no useless flushes.
*/
flush_parent:
return bs->file ? bdrv_co_flush(bs->file->bs) : 0;
}
int bdrv_flush(BlockDriverState *bs)
{
Coroutine *co;
RwCo rwco = {
.bs = bs,
.ret = NOT_DONE,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_flush_co_entry(&rwco);
} else {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_flush_co_entry);
qemu_coroutine_enter(co, &rwco);
while (rwco.ret == NOT_DONE) {
aio_poll(aio_context, true);
}
}
return rwco.ret;
}
typedef struct DiscardCo {
BlockDriverState *bs;
int64_t sector_num;
int nb_sectors;
int ret;
} DiscardCo;
static void coroutine_fn bdrv_discard_co_entry(void *opaque)
{
DiscardCo *rwco = opaque;
rwco->ret = bdrv_co_discard(rwco->bs, rwco->sector_num, rwco->nb_sectors);
}
int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
int nb_sectors)
{
int max_discard, ret;
if (!bs->drv) {
return -ENOMEDIUM;
}
ret = bdrv_check_request(bs, sector_num, nb_sectors);
if (ret < 0) {
return ret;
} else if (bs->read_only) {
return -EPERM;
}
/* Do nothing if disabled. */
if (!(bs->open_flags & BDRV_O_UNMAP)) {
return 0;
}
if (!bs->drv->bdrv_co_discard && !bs->drv->bdrv_aio_discard) {
return 0;
}
bdrv_set_dirty(bs, sector_num, nb_sectors);
max_discard = MIN_NON_ZERO(bs->bl.max_discard, BDRV_REQUEST_MAX_SECTORS);
while (nb_sectors > 0) {
int ret;
int num = nb_sectors;
/* align request */
if (bs->bl.discard_alignment &&
num >= bs->bl.discard_alignment &&
sector_num % bs->bl.discard_alignment) {
if (num > bs->bl.discard_alignment) {
num = bs->bl.discard_alignment;
}
num -= sector_num % bs->bl.discard_alignment;
}
/* limit request size */
if (num > max_discard) {
num = max_discard;
}
if (bs->drv->bdrv_co_discard) {
ret = bs->drv->bdrv_co_discard(bs, sector_num, num);
} else {
BlockAIOCB *acb;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
acb = bs->drv->bdrv_aio_discard(bs, sector_num, nb_sectors,
bdrv_co_io_em_complete, &co);
if (acb == NULL) {
return -EIO;
} else {
qemu_coroutine_yield();
ret = co.ret;
}
}
if (ret && ret != -ENOTSUP) {
return ret;
}
sector_num += num;
nb_sectors -= num;
}
return 0;
}
int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors)
{
Coroutine *co;
DiscardCo rwco = {
.bs = bs,
.sector_num = sector_num,
.nb_sectors = nb_sectors,
.ret = NOT_DONE,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_discard_co_entry(&rwco);
} else {
AioContext *aio_context = bdrv_get_aio_context(bs);
co = qemu_coroutine_create(bdrv_discard_co_entry);
qemu_coroutine_enter(co, &rwco);
while (rwco.ret == NOT_DONE) {
aio_poll(aio_context, true);
}
}
return rwco.ret;
}
/* needed for generic scsi interface */
int bdrv_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_ioctl)
return drv->bdrv_ioctl(bs, req, buf);
return -ENOTSUP;
}
BlockAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
unsigned long int req, void *buf,
BlockCompletionFunc *cb, void *opaque)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_aio_ioctl)
return drv->bdrv_aio_ioctl(bs, req, buf, cb, opaque);
return NULL;
}
void *qemu_blockalign(BlockDriverState *bs, size_t size)
{
return qemu_memalign(bdrv_opt_mem_align(bs), size);
}
void *qemu_blockalign0(BlockDriverState *bs, size_t size)
{
return memset(qemu_blockalign(bs, size), 0, size);
}
void *qemu_try_blockalign(BlockDriverState *bs, size_t size)
{
size_t align = bdrv_opt_mem_align(bs);
/* Ensure that NULL is never returned on success */
assert(align > 0);
if (size == 0) {
size = align;
}
return qemu_try_memalign(align, size);
}
void *qemu_try_blockalign0(BlockDriverState *bs, size_t size)
{
void *mem = qemu_try_blockalign(bs, size);
if (mem) {
memset(mem, 0, size);
}
return mem;
}
/*
* Check if all memory in this vector is sector aligned.
*/
bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov)
{
int i;
size_t alignment = bdrv_min_mem_align(bs);
for (i = 0; i < qiov->niov; i++) {
if ((uintptr_t) qiov->iov[i].iov_base % alignment) {
return false;
}
if (qiov->iov[i].iov_len % alignment) {
return false;
}
}
return true;
}
void bdrv_add_before_write_notifier(BlockDriverState *bs,
NotifierWithReturn *notifier)
{
notifier_with_return_list_add(&bs->before_write_notifiers, notifier);
}
void bdrv_io_plug(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_io_plug) {
drv->bdrv_io_plug(bs);
} else if (bs->file) {
bdrv_io_plug(bs->file->bs);
}
}
void bdrv_io_unplug(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_io_unplug) {
drv->bdrv_io_unplug(bs);
} else if (bs->file) {
bdrv_io_unplug(bs->file->bs);
}
}
void bdrv_flush_io_queue(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_flush_io_queue) {
drv->bdrv_flush_io_queue(bs);
} else if (bs->file) {
bdrv_flush_io_queue(bs->file->bs);
}
bdrv_start_throttled_reqs(bs);
}
void bdrv_drained_begin(BlockDriverState *bs)
{
if (!bs->quiesce_counter++) {
aio_disable_external(bdrv_get_aio_context(bs));
}
bdrv_drain(bs);
}
void bdrv_drained_end(BlockDriverState *bs)
{
assert(bs->quiesce_counter > 0);
if (--bs->quiesce_counter > 0) {
return;
}
aio_enable_external(bdrv_get_aio_context(bs));
}
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