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qemu/block/qed.c
Anthony Liguori 21df65b644 qed: Add support for zero clusters 
Zero clusters are similar to unallocated clusters except instead of reading
their value from a backing file when one is available, the cluster is always
read as zero.

This implements read support only.  At this stage, QED will never write a
zero cluster.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-04-13 12:06:41 +02:00

1384 lines
40 KiB
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/*
* QEMU Enhanced Disk Format
*
* Copyright IBM, Corp. 2010
*
* Authors:
* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "trace.h"
#include "qed.h"
#include "qerror.h"
static void qed_aio_cancel(BlockDriverAIOCB *blockacb)
{
QEDAIOCB *acb = (QEDAIOCB *)blockacb;
bool finished = false;
/* Wait for the request to finish */
acb->finished = &finished;
while (!finished) {
qemu_aio_wait();
}
}
static AIOPool qed_aio_pool = {
.aiocb_size = sizeof(QEDAIOCB),
.cancel = qed_aio_cancel,
};
static int bdrv_qed_probe(const uint8_t *buf, int buf_size,
const char *filename)
{
const QEDHeader *header = (const QEDHeader *)buf;
if (buf_size < sizeof(*header)) {
return 0;
}
if (le32_to_cpu(header->magic) != QED_MAGIC) {
return 0;
}
return 100;
}
/**
* Check whether an image format is raw
*
* @fmt: Backing file format, may be NULL
*/
static bool qed_fmt_is_raw(const char *fmt)
{
return fmt && strcmp(fmt, "raw") == 0;
}
static void qed_header_le_to_cpu(const QEDHeader *le, QEDHeader *cpu)
{
cpu->magic = le32_to_cpu(le->magic);
cpu->cluster_size = le32_to_cpu(le->cluster_size);
cpu->table_size = le32_to_cpu(le->table_size);
cpu->header_size = le32_to_cpu(le->header_size);
cpu->features = le64_to_cpu(le->features);
cpu->compat_features = le64_to_cpu(le->compat_features);
cpu->autoclear_features = le64_to_cpu(le->autoclear_features);
cpu->l1_table_offset = le64_to_cpu(le->l1_table_offset);
cpu->image_size = le64_to_cpu(le->image_size);
cpu->backing_filename_offset = le32_to_cpu(le->backing_filename_offset);
cpu->backing_filename_size = le32_to_cpu(le->backing_filename_size);
}
static void qed_header_cpu_to_le(const QEDHeader *cpu, QEDHeader *le)
{
le->magic = cpu_to_le32(cpu->magic);
le->cluster_size = cpu_to_le32(cpu->cluster_size);
le->table_size = cpu_to_le32(cpu->table_size);
le->header_size = cpu_to_le32(cpu->header_size);
le->features = cpu_to_le64(cpu->features);
le->compat_features = cpu_to_le64(cpu->compat_features);
le->autoclear_features = cpu_to_le64(cpu->autoclear_features);
le->l1_table_offset = cpu_to_le64(cpu->l1_table_offset);
le->image_size = cpu_to_le64(cpu->image_size);
le->backing_filename_offset = cpu_to_le32(cpu->backing_filename_offset);
le->backing_filename_size = cpu_to_le32(cpu->backing_filename_size);
}
static int qed_write_header_sync(BDRVQEDState *s)
{
QEDHeader le;
int ret;
qed_header_cpu_to_le(&s->header, &le);
ret = bdrv_pwrite(s->bs->file, 0, &le, sizeof(le));
if (ret != sizeof(le)) {
return ret;
}
return 0;
}
typedef struct {
GenericCB gencb;
BDRVQEDState *s;
struct iovec iov;
QEMUIOVector qiov;
int nsectors;
uint8_t *buf;
} QEDWriteHeaderCB;
static void qed_write_header_cb(void *opaque, int ret)
{
QEDWriteHeaderCB *write_header_cb = opaque;
qemu_vfree(write_header_cb->buf);
gencb_complete(write_header_cb, ret);
}
static void qed_write_header_read_cb(void *opaque, int ret)
{
QEDWriteHeaderCB *write_header_cb = opaque;
BDRVQEDState *s = write_header_cb->s;
BlockDriverAIOCB *acb;
if (ret) {
qed_write_header_cb(write_header_cb, ret);
return;
}
/* Update header */
qed_header_cpu_to_le(&s->header, (QEDHeader *)write_header_cb->buf);
acb = bdrv_aio_writev(s->bs->file, 0, &write_header_cb->qiov,
write_header_cb->nsectors, qed_write_header_cb,
write_header_cb);
if (!acb) {
qed_write_header_cb(write_header_cb, -EIO);
}
}
/**
* Update header in-place (does not rewrite backing filename or other strings)
*
* This function only updates known header fields in-place and does not affect
* extra data after the QED header.
*/
static void qed_write_header(BDRVQEDState *s, BlockDriverCompletionFunc cb,
void *opaque)
{
/* We must write full sectors for O_DIRECT but cannot necessarily generate
* the data following the header if an unrecognized compat feature is
* active. Therefore, first read the sectors containing the header, update
* them, and write back.
*/
BlockDriverAIOCB *acb;
int nsectors = (sizeof(QEDHeader) + BDRV_SECTOR_SIZE - 1) /
BDRV_SECTOR_SIZE;
size_t len = nsectors * BDRV_SECTOR_SIZE;
QEDWriteHeaderCB *write_header_cb = gencb_alloc(sizeof(*write_header_cb),
cb, opaque);
write_header_cb->s = s;
write_header_cb->nsectors = nsectors;
write_header_cb->buf = qemu_blockalign(s->bs, len);
write_header_cb->iov.iov_base = write_header_cb->buf;
write_header_cb->iov.iov_len = len;
qemu_iovec_init_external(&write_header_cb->qiov, &write_header_cb->iov, 1);
acb = bdrv_aio_readv(s->bs->file, 0, &write_header_cb->qiov, nsectors,
qed_write_header_read_cb, write_header_cb);
if (!acb) {
qed_write_header_cb(write_header_cb, -EIO);
}
}
static uint64_t qed_max_image_size(uint32_t cluster_size, uint32_t table_size)
{
uint64_t table_entries;
uint64_t l2_size;
table_entries = (table_size * cluster_size) / sizeof(uint64_t);
l2_size = table_entries * cluster_size;
return l2_size * table_entries;
}
static bool qed_is_cluster_size_valid(uint32_t cluster_size)
{
if (cluster_size < QED_MIN_CLUSTER_SIZE ||
cluster_size > QED_MAX_CLUSTER_SIZE) {
return false;
}
if (cluster_size & (cluster_size - 1)) {
return false; /* not power of 2 */
}
return true;
}
static bool qed_is_table_size_valid(uint32_t table_size)
{
if (table_size < QED_MIN_TABLE_SIZE ||
table_size > QED_MAX_TABLE_SIZE) {
return false;
}
if (table_size & (table_size - 1)) {
return false; /* not power of 2 */
}
return true;
}
static bool qed_is_image_size_valid(uint64_t image_size, uint32_t cluster_size,
uint32_t table_size)
{
if (image_size % BDRV_SECTOR_SIZE != 0) {
return false; /* not multiple of sector size */
}
if (image_size > qed_max_image_size(cluster_size, table_size)) {
return false; /* image is too large */
}
return true;
}
/**
* Read a string of known length from the image file
*
* @file: Image file
* @offset: File offset to start of string, in bytes
* @n: String length in bytes
* @buf: Destination buffer
* @buflen: Destination buffer length in bytes
* @ret: 0 on success, -errno on failure
*
* The string is NUL-terminated.
*/
static int qed_read_string(BlockDriverState *file, uint64_t offset, size_t n,
char *buf, size_t buflen)
{
int ret;
if (n >= buflen) {
return -EINVAL;
}
ret = bdrv_pread(file, offset, buf, n);
if (ret < 0) {
return ret;
}
buf[n] = '\0';
return 0;
}
/**
* Allocate new clusters
*
* @s: QED state
* @n: Number of contiguous clusters to allocate
* @ret: Offset of first allocated cluster
*
* This function only produces the offset where the new clusters should be
* written. It updates BDRVQEDState but does not make any changes to the image
* file.
*/
static uint64_t qed_alloc_clusters(BDRVQEDState *s, unsigned int n)
{
uint64_t offset = s->file_size;
s->file_size += n * s->header.cluster_size;
return offset;
}
QEDTable *qed_alloc_table(BDRVQEDState *s)
{
/* Honor O_DIRECT memory alignment requirements */
return qemu_blockalign(s->bs,
s->header.cluster_size * s->header.table_size);
}
/**
* Allocate a new zeroed L2 table
*/
static CachedL2Table *qed_new_l2_table(BDRVQEDState *s)
{
CachedL2Table *l2_table = qed_alloc_l2_cache_entry(&s->l2_cache);
l2_table->table = qed_alloc_table(s);
l2_table->offset = qed_alloc_clusters(s, s->header.table_size);
memset(l2_table->table->offsets, 0,
s->header.cluster_size * s->header.table_size);
return l2_table;
}
static void qed_aio_next_io(void *opaque, int ret);
static int bdrv_qed_open(BlockDriverState *bs, int flags)
{
BDRVQEDState *s = bs->opaque;
QEDHeader le_header;
int64_t file_size;
int ret;
s->bs = bs;
QSIMPLEQ_INIT(&s->allocating_write_reqs);
ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header));
if (ret < 0) {
return ret;
}
ret = 0; /* ret should always be 0 or -errno */
qed_header_le_to_cpu(&le_header, &s->header);
if (s->header.magic != QED_MAGIC) {
return -EINVAL;
}
if (s->header.features & ~QED_FEATURE_MASK) {
/* image uses unsupported feature bits */
char buf[64];
snprintf(buf, sizeof(buf), "%" PRIx64,
s->header.features & ~QED_FEATURE_MASK);
qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
bs->device_name, "QED", buf);
return -ENOTSUP;
}
if (!qed_is_cluster_size_valid(s->header.cluster_size)) {
return -EINVAL;
}
/* Round down file size to the last cluster */
file_size = bdrv_getlength(bs->file);
if (file_size < 0) {
return file_size;
}
s->file_size = qed_start_of_cluster(s, file_size);
if (!qed_is_table_size_valid(s->header.table_size)) {
return -EINVAL;
}
if (!qed_is_image_size_valid(s->header.image_size,
s->header.cluster_size,
s->header.table_size)) {
return -EINVAL;
}
if (!qed_check_table_offset(s, s->header.l1_table_offset)) {
return -EINVAL;
}
s->table_nelems = (s->header.cluster_size * s->header.table_size) /
sizeof(uint64_t);
s->l2_shift = ffs(s->header.cluster_size) - 1;
s->l2_mask = s->table_nelems - 1;
s->l1_shift = s->l2_shift + ffs(s->table_nelems) - 1;
if ((s->header.features & QED_F_BACKING_FILE)) {
if ((uint64_t)s->header.backing_filename_offset +
s->header.backing_filename_size >
s->header.cluster_size * s->header.header_size) {
return -EINVAL;
}
ret = qed_read_string(bs->file, s->header.backing_filename_offset,
s->header.backing_filename_size, bs->backing_file,
sizeof(bs->backing_file));
if (ret < 0) {
return ret;
}
if (s->header.features & QED_F_BACKING_FORMAT_NO_PROBE) {
pstrcpy(bs->backing_format, sizeof(bs->backing_format), "raw");
}
}
/* Reset unknown autoclear feature bits. This is a backwards
* compatibility mechanism that allows images to be opened by older
* programs, which "knock out" unknown feature bits. When an image is
* opened by a newer program again it can detect that the autoclear
* feature is no longer valid.
*/
if ((s->header.autoclear_features & ~QED_AUTOCLEAR_FEATURE_MASK) != 0 &&
!bdrv_is_read_only(bs->file)) {
s->header.autoclear_features &= QED_AUTOCLEAR_FEATURE_MASK;
ret = qed_write_header_sync(s);
if (ret) {
return ret;
}
/* From here on only known autoclear feature bits are valid */
bdrv_flush(bs->file);
}
s->l1_table = qed_alloc_table(s);
qed_init_l2_cache(&s->l2_cache);
ret = qed_read_l1_table_sync(s);
if (ret) {
goto out;
}
/* If image was not closed cleanly, check consistency */
if (s->header.features & QED_F_NEED_CHECK) {
/* Read-only images cannot be fixed. There is no risk of corruption
* since write operations are not possible. Therefore, allow
* potentially inconsistent images to be opened read-only. This can
* aid data recovery from an otherwise inconsistent image.
*/
if (!bdrv_is_read_only(bs->file)) {
BdrvCheckResult result = {0};
ret = qed_check(s, &result, true);
if (!ret && !result.corruptions && !result.check_errors) {
/* Ensure fixes reach storage before clearing check bit */
bdrv_flush(s->bs);
s->header.features &= ~QED_F_NEED_CHECK;
qed_write_header_sync(s);
}
}
}
out:
if (ret) {
qed_free_l2_cache(&s->l2_cache);
qemu_vfree(s->l1_table);
}
return ret;
}
static void bdrv_qed_close(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
/* Ensure writes reach stable storage */
bdrv_flush(bs->file);
/* Clean shutdown, no check required on next open */
if (s->header.features & QED_F_NEED_CHECK) {
s->header.features &= ~QED_F_NEED_CHECK;
qed_write_header_sync(s);
}
qed_free_l2_cache(&s->l2_cache);
qemu_vfree(s->l1_table);
}
static int bdrv_qed_flush(BlockDriverState *bs)
{
return bdrv_flush(bs->file);
}
static int qed_create(const char *filename, uint32_t cluster_size,
uint64_t image_size, uint32_t table_size,
const char *backing_file, const char *backing_fmt)
{
QEDHeader header = {
.magic = QED_MAGIC,
.cluster_size = cluster_size,
.table_size = table_size,
.header_size = 1,
.features = 0,
.compat_features = 0,
.l1_table_offset = cluster_size,
.image_size = image_size,
};
QEDHeader le_header;
uint8_t *l1_table = NULL;
size_t l1_size = header.cluster_size * header.table_size;
int ret = 0;
BlockDriverState *bs = NULL;
ret = bdrv_create_file(filename, NULL);
if (ret < 0) {
return ret;
}
ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR | BDRV_O_CACHE_WB);
if (ret < 0) {
return ret;
}
/* File must start empty and grow, check truncate is supported */
ret = bdrv_truncate(bs, 0);
if (ret < 0) {
goto out;
}
if (backing_file) {
header.features |= QED_F_BACKING_FILE;
header.backing_filename_offset = sizeof(le_header);
header.backing_filename_size = strlen(backing_file);
if (qed_fmt_is_raw(backing_fmt)) {
header.features |= QED_F_BACKING_FORMAT_NO_PROBE;
}
}
qed_header_cpu_to_le(&header, &le_header);
ret = bdrv_pwrite(bs, 0, &le_header, sizeof(le_header));
if (ret < 0) {
goto out;
}
ret = bdrv_pwrite(bs, sizeof(le_header), backing_file,
header.backing_filename_size);
if (ret < 0) {
goto out;
}
l1_table = qemu_mallocz(l1_size);
ret = bdrv_pwrite(bs, header.l1_table_offset, l1_table, l1_size);
if (ret < 0) {
goto out;
}
ret = 0; /* success */
out:
qemu_free(l1_table);
bdrv_delete(bs);
return ret;
}
static int bdrv_qed_create(const char *filename, QEMUOptionParameter *options)
{
uint64_t image_size = 0;
uint32_t cluster_size = QED_DEFAULT_CLUSTER_SIZE;
uint32_t table_size = QED_DEFAULT_TABLE_SIZE;
const char *backing_file = NULL;
const char *backing_fmt = NULL;
while (options && options->name) {
if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
image_size = options->value.n;
} else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) {
backing_file = options->value.s;
} else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) {
backing_fmt = options->value.s;
} else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {
if (options->value.n) {
cluster_size = options->value.n;
}
} else if (!strcmp(options->name, BLOCK_OPT_TABLE_SIZE)) {
if (options->value.n) {
table_size = options->value.n;
}
}
options++;
}
if (!qed_is_cluster_size_valid(cluster_size)) {
fprintf(stderr, "QED cluster size must be within range [%u, %u] and power of 2\n",
QED_MIN_CLUSTER_SIZE, QED_MAX_CLUSTER_SIZE);
return -EINVAL;
}
if (!qed_is_table_size_valid(table_size)) {
fprintf(stderr, "QED table size must be within range [%u, %u] and power of 2\n",
QED_MIN_TABLE_SIZE, QED_MAX_TABLE_SIZE);
return -EINVAL;
}
if (!qed_is_image_size_valid(image_size, cluster_size, table_size)) {
fprintf(stderr, "QED image size must be a non-zero multiple of "
"cluster size and less than %" PRIu64 " bytes\n",
qed_max_image_size(cluster_size, table_size));
return -EINVAL;
}
return qed_create(filename, cluster_size, image_size, table_size,
backing_file, backing_fmt);
}
typedef struct {
int is_allocated;
int *pnum;
} QEDIsAllocatedCB;
static void qed_is_allocated_cb(void *opaque, int ret, uint64_t offset, size_t len)
{
QEDIsAllocatedCB *cb = opaque;
*cb->pnum = len / BDRV_SECTOR_SIZE;
cb->is_allocated = (ret == QED_CLUSTER_FOUND || ret == QED_CLUSTER_ZERO);
}
static int bdrv_qed_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
BDRVQEDState *s = bs->opaque;
uint64_t pos = (uint64_t)sector_num * BDRV_SECTOR_SIZE;
size_t len = (size_t)nb_sectors * BDRV_SECTOR_SIZE;
QEDIsAllocatedCB cb = {
.is_allocated = -1,
.pnum = pnum,
};
QEDRequest request = { .l2_table = NULL };
async_context_push();
qed_find_cluster(s, &request, pos, len, qed_is_allocated_cb, &cb);
while (cb.is_allocated == -1) {
qemu_aio_wait();
}
async_context_pop();
qed_unref_l2_cache_entry(request.l2_table);
return cb.is_allocated;
}
static int bdrv_qed_make_empty(BlockDriverState *bs)
{
return -ENOTSUP;
}
static BDRVQEDState *acb_to_s(QEDAIOCB *acb)
{
return acb->common.bs->opaque;
}
/**
* Read from the backing file or zero-fill if no backing file
*
* @s: QED state
* @pos: Byte position in device
* @qiov: Destination I/O vector
* @cb: Completion function
* @opaque: User data for completion function
*
* This function reads qiov->size bytes starting at pos from the backing file.
* If there is no backing file then zeroes are read.
*/
static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
QEMUIOVector *qiov,
BlockDriverCompletionFunc *cb, void *opaque)
{
BlockDriverAIOCB *aiocb;
uint64_t backing_length = 0;
size_t size;
/* If there is a backing file, get its length. Treat the absence of a
* backing file like a zero length backing file.
*/
if (s->bs->backing_hd) {
int64_t l = bdrv_getlength(s->bs->backing_hd);
if (l < 0) {
cb(opaque, l);
return;
}
backing_length = l;
}
/* Zero all sectors if reading beyond the end of the backing file */
if (pos >= backing_length ||
pos + qiov->size > backing_length) {
qemu_iovec_memset(qiov, 0, qiov->size);
}
/* Complete now if there are no backing file sectors to read */
if (pos >= backing_length) {
cb(opaque, 0);
return;
}
/* If the read straddles the end of the backing file, shorten it */
size = MIN((uint64_t)backing_length - pos, qiov->size);
BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING);
aiocb = bdrv_aio_readv(s->bs->backing_hd, pos / BDRV_SECTOR_SIZE,
qiov, size / BDRV_SECTOR_SIZE, cb, opaque);
if (!aiocb) {
cb(opaque, -EIO);
}
}
typedef struct {
GenericCB gencb;
BDRVQEDState *s;
QEMUIOVector qiov;
struct iovec iov;
uint64_t offset;
} CopyFromBackingFileCB;
static void qed_copy_from_backing_file_cb(void *opaque, int ret)
{
CopyFromBackingFileCB *copy_cb = opaque;
qemu_vfree(copy_cb->iov.iov_base);
gencb_complete(&copy_cb->gencb, ret);
}
static void qed_copy_from_backing_file_write(void *opaque, int ret)
{
CopyFromBackingFileCB *copy_cb = opaque;
BDRVQEDState *s = copy_cb->s;
BlockDriverAIOCB *aiocb;
if (ret) {
qed_copy_from_backing_file_cb(copy_cb, ret);
return;
}
BLKDBG_EVENT(s->bs->file, BLKDBG_COW_WRITE);
aiocb = bdrv_aio_writev(s->bs->file, copy_cb->offset / BDRV_SECTOR_SIZE,
&copy_cb->qiov,
copy_cb->qiov.size / BDRV_SECTOR_SIZE,
qed_copy_from_backing_file_cb, copy_cb);
if (!aiocb) {
qed_copy_from_backing_file_cb(copy_cb, -EIO);
}
}
/**
* Copy data from backing file into the image
*
* @s: QED state
* @pos: Byte position in device
* @len: Number of bytes
* @offset: Byte offset in image file
* @cb: Completion function
* @opaque: User data for completion function
*/
static void qed_copy_from_backing_file(BDRVQEDState *s, uint64_t pos,
uint64_t len, uint64_t offset,
BlockDriverCompletionFunc *cb,
void *opaque)
{
CopyFromBackingFileCB *copy_cb;
/* Skip copy entirely if there is no work to do */
if (len == 0) {
cb(opaque, 0);
return;
}
copy_cb = gencb_alloc(sizeof(*copy_cb), cb, opaque);
copy_cb->s = s;
copy_cb->offset = offset;
copy_cb->iov.iov_base = qemu_blockalign(s->bs, len);
copy_cb->iov.iov_len = len;
qemu_iovec_init_external(&copy_cb->qiov, &copy_cb->iov, 1);
qed_read_backing_file(s, pos, &copy_cb->qiov,
qed_copy_from_backing_file_write, copy_cb);
}
/**
* Link one or more contiguous clusters into a table
*
* @s: QED state
* @table: L2 table
* @index: First cluster index
* @n: Number of contiguous clusters
* @cluster: First cluster offset
*
* The cluster offset may be an allocated byte offset in the image file, the
* zero cluster marker, or the unallocated cluster marker.
*/
static void qed_update_l2_table(BDRVQEDState *s, QEDTable *table, int index,
unsigned int n, uint64_t cluster)
{
int i;
for (i = index; i < index + n; i++) {
table->offsets[i] = cluster;
if (!qed_offset_is_unalloc_cluster(cluster) &&
!qed_offset_is_zero_cluster(cluster)) {
cluster += s->header.cluster_size;
}
}
}
static void qed_aio_complete_bh(void *opaque)
{
QEDAIOCB *acb = opaque;
BlockDriverCompletionFunc *cb = acb->common.cb;
void *user_opaque = acb->common.opaque;
int ret = acb->bh_ret;
bool *finished = acb->finished;
qemu_bh_delete(acb->bh);
qemu_aio_release(acb);
/* Invoke callback */
cb(user_opaque, ret);
/* Signal cancel completion */
if (finished) {
*finished = true;
}
}
static void qed_aio_complete(QEDAIOCB *acb, int ret)
{
BDRVQEDState *s = acb_to_s(acb);
trace_qed_aio_complete(s, acb, ret);
/* Free resources */
qemu_iovec_destroy(&acb->cur_qiov);
qed_unref_l2_cache_entry(acb->request.l2_table);
/* Arrange for a bh to invoke the completion function */
acb->bh_ret = ret;
acb->bh = qemu_bh_new(qed_aio_complete_bh, acb);
qemu_bh_schedule(acb->bh);
/* Start next allocating write request waiting behind this one. Note that
* requests enqueue themselves when they first hit an unallocated cluster
* but they wait until the entire request is finished before waking up the
* next request in the queue. This ensures that we don't cycle through
* requests multiple times but rather finish one at a time completely.
*/
if (acb == QSIMPLEQ_FIRST(&s->allocating_write_reqs)) {
QSIMPLEQ_REMOVE_HEAD(&s->allocating_write_reqs, next);
acb = QSIMPLEQ_FIRST(&s->allocating_write_reqs);
if (acb) {
qed_aio_next_io(acb, 0);
}
}
}
/**
* Commit the current L2 table to the cache
*/
static void qed_commit_l2_update(void *opaque, int ret)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
CachedL2Table *l2_table = acb->request.l2_table;
qed_commit_l2_cache_entry(&s->l2_cache, l2_table);
/* This is guaranteed to succeed because we just committed the entry to the
* cache.
*/
acb->request.l2_table = qed_find_l2_cache_entry(&s->l2_cache,
l2_table->offset);
assert(acb->request.l2_table != NULL);
qed_aio_next_io(opaque, ret);
}
/**
* Update L1 table with new L2 table offset and write it out
*/
static void qed_aio_write_l1_update(void *opaque, int ret)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
int index;
if (ret) {
qed_aio_complete(acb, ret);
return;
}
index = qed_l1_index(s, acb->cur_pos);
s->l1_table->offsets[index] = acb->request.l2_table->offset;
qed_write_l1_table(s, index, 1, qed_commit_l2_update, acb);
}
/**
* Update L2 table with new cluster offsets and write them out
*/
static void qed_aio_write_l2_update(void *opaque, int ret)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
bool need_alloc = acb->find_cluster_ret == QED_CLUSTER_L1;
int index;
if (ret) {
goto err;
}
if (need_alloc) {
qed_unref_l2_cache_entry(acb->request.l2_table);
acb->request.l2_table = qed_new_l2_table(s);
}
index = qed_l2_index(s, acb->cur_pos);
qed_update_l2_table(s, acb->request.l2_table->table, index, acb->cur_nclusters,
acb->cur_cluster);
if (need_alloc) {
/* Write out the whole new L2 table */
qed_write_l2_table(s, &acb->request, 0, s->table_nelems, true,
qed_aio_write_l1_update, acb);
} else {
/* Write out only the updated part of the L2 table */
qed_write_l2_table(s, &acb->request, index, acb->cur_nclusters, false,
qed_aio_next_io, acb);
}
return;
err:
qed_aio_complete(acb, ret);
}
/**
* Flush new data clusters before updating the L2 table
*
* This flush is necessary when a backing file is in use. A crash during an
* allocating write could result in empty clusters in the image. If the write
* only touched a subregion of the cluster, then backing image sectors have
* been lost in the untouched region. The solution is to flush after writing a
* new data cluster and before updating the L2 table.
*/
static void qed_aio_write_flush_before_l2_update(void *opaque, int ret)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
if (!bdrv_aio_flush(s->bs->file, qed_aio_write_l2_update, opaque)) {
qed_aio_complete(acb, -EIO);
}
}
/**
* Write data to the image file
*/
static void qed_aio_write_main(void *opaque, int ret)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
uint64_t offset = acb->cur_cluster +
qed_offset_into_cluster(s, acb->cur_pos);
BlockDriverCompletionFunc *next_fn;
BlockDriverAIOCB *file_acb;
trace_qed_aio_write_main(s, acb, ret, offset, acb->cur_qiov.size);
if (ret) {
qed_aio_complete(acb, ret);
return;
}
if (acb->find_cluster_ret == QED_CLUSTER_FOUND) {
next_fn = qed_aio_next_io;
} else {
if (s->bs->backing_hd) {
next_fn = qed_aio_write_flush_before_l2_update;
} else {
next_fn = qed_aio_write_l2_update;
}
}
BLKDBG_EVENT(s->bs->file, BLKDBG_WRITE_AIO);
file_acb = bdrv_aio_writev(s->bs->file, offset / BDRV_SECTOR_SIZE,
&acb->cur_qiov,
acb->cur_qiov.size / BDRV_SECTOR_SIZE,
next_fn, acb);
if (!file_acb) {
qed_aio_complete(acb, -EIO);
}
}
/**
* Populate back untouched region of new data cluster
*/
static void qed_aio_write_postfill(void *opaque, int ret)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
uint64_t start = acb->cur_pos + acb->cur_qiov.size;
uint64_t len =
qed_start_of_cluster(s, start + s->header.cluster_size - 1) - start;
uint64_t offset = acb->cur_cluster +
qed_offset_into_cluster(s, acb->cur_pos) +
acb->cur_qiov.size;
if (ret) {
qed_aio_complete(acb, ret);
return;
}
trace_qed_aio_write_postfill(s, acb, start, len, offset);
qed_copy_from_backing_file(s, start, len, offset,
qed_aio_write_main, acb);
}
/**
* Populate front untouched region of new data cluster
*/
static void qed_aio_write_prefill(void *opaque, int ret)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
uint64_t start = qed_start_of_cluster(s, acb->cur_pos);
uint64_t len = qed_offset_into_cluster(s, acb->cur_pos);
trace_qed_aio_write_prefill(s, acb, start, len, acb->cur_cluster);
qed_copy_from_backing_file(s, start, len, acb->cur_cluster,
qed_aio_write_postfill, acb);
}
/**
* Check if the QED_F_NEED_CHECK bit should be set during allocating write
*/
static bool qed_should_set_need_check(BDRVQEDState *s)
{
/* The flush before L2 update path ensures consistency */
if (s->bs->backing_hd) {
return false;
}
return !(s->header.features & QED_F_NEED_CHECK);
}
/**
* Write new data cluster
*
* @acb: Write request
* @len: Length in bytes
*
* This path is taken when writing to previously unallocated clusters.
*/
static void qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
{
BDRVQEDState *s = acb_to_s(acb);
/* Freeze this request if another allocating write is in progress */
if (acb != QSIMPLEQ_FIRST(&s->allocating_write_reqs)) {
QSIMPLEQ_INSERT_TAIL(&s->allocating_write_reqs, acb, next);
}
if (acb != QSIMPLEQ_FIRST(&s->allocating_write_reqs)) {
return; /* wait for existing request to finish */
}
acb->cur_nclusters = qed_bytes_to_clusters(s,
qed_offset_into_cluster(s, acb->cur_pos) + len);
acb->cur_cluster = qed_alloc_clusters(s, acb->cur_nclusters);
qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len);
if (qed_should_set_need_check(s)) {
s->header.features |= QED_F_NEED_CHECK;
qed_write_header(s, qed_aio_write_prefill, acb);
} else {
qed_aio_write_prefill(acb, 0);
}
}
/**
* Write data cluster in place
*
* @acb: Write request
* @offset: Cluster offset in bytes
* @len: Length in bytes
*
* This path is taken when writing to already allocated clusters.
*/
static void qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset, size_t len)
{
/* Calculate the I/O vector */
acb->cur_cluster = offset;
qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len);
/* Do the actual write */
qed_aio_write_main(acb, 0);
}
/**
* Write data cluster
*
* @opaque: Write request
* @ret: QED_CLUSTER_FOUND, QED_CLUSTER_L2, QED_CLUSTER_L1,
* or -errno
* @offset: Cluster offset in bytes
* @len: Length in bytes
*
* Callback from qed_find_cluster().
*/
static void qed_aio_write_data(void *opaque, int ret,
uint64_t offset, size_t len)
{
QEDAIOCB *acb = opaque;
trace_qed_aio_write_data(acb_to_s(acb), acb, ret, offset, len);
acb->find_cluster_ret = ret;
switch (ret) {
case QED_CLUSTER_FOUND:
qed_aio_write_inplace(acb, offset, len);
break;
case QED_CLUSTER_L2:
case QED_CLUSTER_L1:
case QED_CLUSTER_ZERO:
qed_aio_write_alloc(acb, len);
break;
default:
qed_aio_complete(acb, ret);
break;
}
}
/**
* Read data cluster
*
* @opaque: Read request
* @ret: QED_CLUSTER_FOUND, QED_CLUSTER_L2, QED_CLUSTER_L1,
* or -errno
* @offset: Cluster offset in bytes
* @len: Length in bytes
*
* Callback from qed_find_cluster().
*/
static void qed_aio_read_data(void *opaque, int ret,
uint64_t offset, size_t len)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
BlockDriverState *bs = acb->common.bs;
BlockDriverAIOCB *file_acb;
/* Adjust offset into cluster */
offset += qed_offset_into_cluster(s, acb->cur_pos);
trace_qed_aio_read_data(s, acb, ret, offset, len);
if (ret < 0) {
goto err;
}
qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len);
/* Handle zero cluster and backing file reads */
if (ret == QED_CLUSTER_ZERO) {
qemu_iovec_memset(&acb->cur_qiov, 0, acb->cur_qiov.size);
qed_aio_next_io(acb, 0);
return;
} else if (ret != QED_CLUSTER_FOUND) {
qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov,
qed_aio_next_io, acb);
return;
}
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
file_acb = bdrv_aio_readv(bs->file, offset / BDRV_SECTOR_SIZE,
&acb->cur_qiov,
acb->cur_qiov.size / BDRV_SECTOR_SIZE,
qed_aio_next_io, acb);
if (!file_acb) {
ret = -EIO;
goto err;
}
return;
err:
qed_aio_complete(acb, ret);
}
/**
* Begin next I/O or complete the request
*/
static void qed_aio_next_io(void *opaque, int ret)
{
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
QEDFindClusterFunc *io_fn =
acb->is_write ? qed_aio_write_data : qed_aio_read_data;
trace_qed_aio_next_io(s, acb, ret, acb->cur_pos + acb->cur_qiov.size);
/* Handle I/O error */
if (ret) {
qed_aio_complete(acb, ret);
return;
}
acb->qiov_offset += acb->cur_qiov.size;
acb->cur_pos += acb->cur_qiov.size;
qemu_iovec_reset(&acb->cur_qiov);
/* Complete request */
if (acb->cur_pos >= acb->end_pos) {
qed_aio_complete(acb, 0);
return;
}
/* Find next cluster and start I/O */
qed_find_cluster(s, &acb->request,
acb->cur_pos, acb->end_pos - acb->cur_pos,
io_fn, acb);
}
static BlockDriverAIOCB *qed_aio_setup(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb,
void *opaque, bool is_write)
{
QEDAIOCB *acb = qemu_aio_get(&qed_aio_pool, bs, cb, opaque);
trace_qed_aio_setup(bs->opaque, acb, sector_num, nb_sectors,
opaque, is_write);
acb->is_write = is_write;
acb->finished = NULL;
acb->qiov = qiov;
acb->qiov_offset = 0;
acb->cur_pos = (uint64_t)sector_num * BDRV_SECTOR_SIZE;
acb->end_pos = acb->cur_pos + nb_sectors * BDRV_SECTOR_SIZE;
acb->request.l2_table = NULL;
qemu_iovec_init(&acb->cur_qiov, qiov->niov);
/* Start request */
qed_aio_next_io(acb, 0);
return &acb->common;
}
static BlockDriverAIOCB *bdrv_qed_aio_readv(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb,
void *opaque)
{
return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, false);
}
static BlockDriverAIOCB *bdrv_qed_aio_writev(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb,
void *opaque)
{
return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, true);
}
static BlockDriverAIOCB *bdrv_qed_aio_flush(BlockDriverState *bs,
BlockDriverCompletionFunc *cb,
void *opaque)
{
return bdrv_aio_flush(bs->file, cb, opaque);
}
static int bdrv_qed_truncate(BlockDriverState *bs, int64_t offset)
{
return -ENOTSUP;
}
static int64_t bdrv_qed_getlength(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
return s->header.image_size;
}
static int bdrv_qed_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
BDRVQEDState *s = bs->opaque;
memset(bdi, 0, sizeof(*bdi));
bdi->cluster_size = s->header.cluster_size;
return 0;
}
static int bdrv_qed_change_backing_file(BlockDriverState *bs,
const char *backing_file,
const char *backing_fmt)
{
BDRVQEDState *s = bs->opaque;
QEDHeader new_header, le_header;
void *buffer;
size_t buffer_len, backing_file_len;
int ret;
/* Refuse to set backing filename if unknown compat feature bits are
* active. If the image uses an unknown compat feature then we may not
* know the layout of data following the header structure and cannot safely
* add a new string.
*/
if (backing_file && (s->header.compat_features &
~QED_COMPAT_FEATURE_MASK)) {
return -ENOTSUP;
}
memcpy(&new_header, &s->header, sizeof(new_header));
new_header.features &= ~(QED_F_BACKING_FILE |
QED_F_BACKING_FORMAT_NO_PROBE);
/* Adjust feature flags */
if (backing_file) {
new_header.features |= QED_F_BACKING_FILE;
if (qed_fmt_is_raw(backing_fmt)) {
new_header.features |= QED_F_BACKING_FORMAT_NO_PROBE;
}
}
/* Calculate new header size */
backing_file_len = 0;
if (backing_file) {
backing_file_len = strlen(backing_file);
}
buffer_len = sizeof(new_header);
new_header.backing_filename_offset = buffer_len;
new_header.backing_filename_size = backing_file_len;
buffer_len += backing_file_len;
/* Make sure we can rewrite header without failing */
if (buffer_len > new_header.header_size * new_header.cluster_size) {
return -ENOSPC;
}
/* Prepare new header */
buffer = qemu_malloc(buffer_len);
qed_header_cpu_to_le(&new_header, &le_header);
memcpy(buffer, &le_header, sizeof(le_header));
buffer_len = sizeof(le_header);
memcpy(buffer + buffer_len, backing_file, backing_file_len);
buffer_len += backing_file_len;
/* Write new header */
ret = bdrv_pwrite_sync(bs->file, 0, buffer, buffer_len);
qemu_free(buffer);
if (ret == 0) {
memcpy(&s->header, &new_header, sizeof(new_header));
}
return ret;
}
static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result)
{
BDRVQEDState *s = bs->opaque;
return qed_check(s, result, false);
}
static QEMUOptionParameter qed_create_options[] = {
{
.name = BLOCK_OPT_SIZE,
.type = OPT_SIZE,
.help = "Virtual disk size (in bytes)"
}, {
.name = BLOCK_OPT_BACKING_FILE,
.type = OPT_STRING,
.help = "File name of a base image"
}, {
.name = BLOCK_OPT_BACKING_FMT,
.type = OPT_STRING,
.help = "Image format of the base image"
}, {
.name = BLOCK_OPT_CLUSTER_SIZE,
.type = OPT_SIZE,
.help = "Cluster size (in bytes)"
}, {
.name = BLOCK_OPT_TABLE_SIZE,
.type = OPT_SIZE,
.help = "L1/L2 table size (in clusters)"
},
{ /* end of list */ }
};
static BlockDriver bdrv_qed = {
.format_name = "qed",
.instance_size = sizeof(BDRVQEDState),
.create_options = qed_create_options,
.bdrv_probe = bdrv_qed_probe,
.bdrv_open = bdrv_qed_open,
.bdrv_close = bdrv_qed_close,
.bdrv_create = bdrv_qed_create,
.bdrv_flush = bdrv_qed_flush,
.bdrv_is_allocated = bdrv_qed_is_allocated,
.bdrv_make_empty = bdrv_qed_make_empty,
.bdrv_aio_readv = bdrv_qed_aio_readv,
.bdrv_aio_writev = bdrv_qed_aio_writev,
.bdrv_aio_flush = bdrv_qed_aio_flush,
.bdrv_truncate = bdrv_qed_truncate,
.bdrv_getlength = bdrv_qed_getlength,
.bdrv_get_info = bdrv_qed_get_info,
.bdrv_change_backing_file = bdrv_qed_change_backing_file,
.bdrv_check = bdrv_qed_check,
};
static void bdrv_qed_init(void)
{
bdrv_register(&bdrv_qed);
}
block_init(bdrv_qed_init);
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