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qed.c
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/*
* QEMU Enhanced Disk Format
*
* Copyright IBM, Corp. 2010
*
* Authors:
* Stefan Hajnoczi <[email protected]>
* Anthony Liguori <[email protected]>
*
* 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 "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/timer.h"
#include "qemu/bswap.h"
#include "qemu/option.h"
#include "trace.h"
#include "qed.h"
#include "sysemu/block-backend.h"
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);
}
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;
}
/**
* 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.
*
* No new allocating reqs can start while this function runs.
*/
static int coroutine_fn qed_write_header(BDRVQEDState *s)
{
/* 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.
*/
int nsectors = DIV_ROUND_UP(sizeof(QEDHeader), BDRV_SECTOR_SIZE);
size_t len = nsectors * BDRV_SECTOR_SIZE;
uint8_t *buf;
struct iovec iov;
QEMUIOVector qiov;
int ret;
assert(s->allocating_acb || s->allocating_write_reqs_plugged);
buf = qemu_blockalign(s->bs, len);
iov = (struct iovec) {
.iov_base = buf,
.iov_len = len,
};
qemu_iovec_init_external(&qiov, &iov, 1);
ret = bdrv_co_preadv(s->bs->file, 0, qiov.size, &qiov, 0);
if (ret < 0) {
goto out;
}
/* Update header */
qed_header_cpu_to_le(&s->header, (QEDHeader *) buf);
ret = bdrv_co_pwritev(s->bs->file, 0, qiov.size, &qiov, 0);
if (ret < 0) {
goto out;
}
ret = 0;
out:
qemu_vfree(buf);
return ret;
}
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(BdrvChild *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.
*
* Called with table_lock held.
*/
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
*
* Called with table_lock held.
*/
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 bool qed_plug_allocating_write_reqs(BDRVQEDState *s)
{
qemu_co_mutex_lock(&s->table_lock);
/* No reentrancy is allowed. */
assert(!s->allocating_write_reqs_plugged);
if (s->allocating_acb != NULL) {
/* Another allocating write came concurrently. This cannot happen
* from bdrv_qed_co_drain_begin, but it can happen when the timer runs.
*/
qemu_co_mutex_unlock(&s->table_lock);
return false;
}
s->allocating_write_reqs_plugged = true;
qemu_co_mutex_unlock(&s->table_lock);
return true;
}
static void qed_unplug_allocating_write_reqs(BDRVQEDState *s)
{
qemu_co_mutex_lock(&s->table_lock);
assert(s->allocating_write_reqs_plugged);
s->allocating_write_reqs_plugged = false;
qemu_co_queue_next(&s->allocating_write_reqs);
qemu_co_mutex_unlock(&s->table_lock);
}
static void coroutine_fn qed_need_check_timer_entry(void *opaque)
{
BDRVQEDState *s = opaque;
int ret;
trace_qed_need_check_timer_cb(s);
if (!qed_plug_allocating_write_reqs(s)) {
return;
}
/* Ensure writes are on disk before clearing flag */
ret = bdrv_co_flush(s->bs->file->bs);
if (ret < 0) {
qed_unplug_allocating_write_reqs(s);
return;
}
s->header.features &= ~QED_F_NEED_CHECK;
ret = qed_write_header(s);
(void) ret;
qed_unplug_allocating_write_reqs(s);
ret = bdrv_co_flush(s->bs);
(void) ret;
}
static void qed_need_check_timer_cb(void *opaque)
{
Coroutine *co = qemu_coroutine_create(qed_need_check_timer_entry, opaque);
qemu_coroutine_enter(co);
}
static void qed_start_need_check_timer(BDRVQEDState *s)
{
trace_qed_start_need_check_timer(s);
/* Use QEMU_CLOCK_VIRTUAL so we don't alter the image file while suspended for
* migration.
*/
timer_mod(s->need_check_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
NANOSECONDS_PER_SECOND * QED_NEED_CHECK_TIMEOUT);
}
/* It's okay to call this multiple times or when no timer is started */
static void qed_cancel_need_check_timer(BDRVQEDState *s)
{
trace_qed_cancel_need_check_timer(s);
timer_del(s->need_check_timer);
}
static void bdrv_qed_detach_aio_context(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
qed_cancel_need_check_timer(s);
timer_free(s->need_check_timer);
}
static void bdrv_qed_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
BDRVQEDState *s = bs->opaque;
s->need_check_timer = aio_timer_new(new_context,
QEMU_CLOCK_VIRTUAL, SCALE_NS,
qed_need_check_timer_cb, s);
if (s->header.features & QED_F_NEED_CHECK) {
qed_start_need_check_timer(s);
}
}
static void coroutine_fn bdrv_qed_co_drain_begin(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
/* Fire the timer immediately in order to start doing I/O as soon as the
* header is flushed.
*/
if (s->need_check_timer && timer_pending(s->need_check_timer)) {
qed_cancel_need_check_timer(s);
qed_need_check_timer_entry(s);
}
}
static void bdrv_qed_init_state(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
memset(s, 0, sizeof(BDRVQEDState));
s->bs = bs;
qemu_co_mutex_init(&s->table_lock);
qemu_co_queue_init(&s->allocating_write_reqs);
}
/* Called with table_lock held. */
static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,
int flags, Error **errp)
{
BDRVQEDState *s = bs->opaque;
QEDHeader le_header;
int64_t file_size;
int ret;
ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header));
if (ret < 0) {
return ret;
}
qed_header_le_to_cpu(&le_header, &s->header);
if (s->header.magic != QED_MAGIC) {
error_setg(errp, "Image not in QED format");
return -EINVAL;
}
if (s->header.features & ~QED_FEATURE_MASK) {
/* image uses unsupported feature bits */
error_setg(errp, "Unsupported QED features: %" PRIx64,
s->header.features & ~QED_FEATURE_MASK);
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->bs);
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 = ctz32(s->header.cluster_size);
s->l2_mask = s->table_nelems - 1;
s->l1_shift = s->l2_shift + ctz32(s->table_nelems);
/* Header size calculation must not overflow uint32_t */
if (s->header.header_size > UINT32_MAX / s->header.cluster_size) {
return -EINVAL;
}
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->bs) && !(flags & BDRV_O_INACTIVE)) {
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->bs);
}
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 (!(flags & BDRV_O_CHECK) && (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->bs) &&
!(flags & BDRV_O_INACTIVE)) {
BdrvCheckResult result = {0};
ret = qed_check(s, &result, true);
if (ret) {
goto out;
}
}
}
bdrv_qed_attach_aio_context(bs, bdrv_get_aio_context(bs));
out:
if (ret) {
qed_free_l2_cache(&s->l2_cache);
qemu_vfree(s->l1_table);
}
return ret;
}
typedef struct QEDOpenCo {
BlockDriverState *bs;
QDict *options;
int flags;
Error **errp;
int ret;
} QEDOpenCo;
static void coroutine_fn bdrv_qed_open_entry(void *opaque)
{
QEDOpenCo *qoc = opaque;
BDRVQEDState *s = qoc->bs->opaque;
qemu_co_mutex_lock(&s->table_lock);
qoc->ret = bdrv_qed_do_open(qoc->bs, qoc->options, qoc->flags, qoc->errp);
qemu_co_mutex_unlock(&s->table_lock);
}
static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
QEDOpenCo qoc = {
.bs = bs,
.options = options,
.flags = flags,
.errp = errp,
.ret = -EINPROGRESS
};
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
false, errp);
if (!bs->file) {
return -EINVAL;
}
bdrv_qed_init_state(bs);
if (qemu_in_coroutine()) {
bdrv_qed_open_entry(&qoc);
} else {
qemu_coroutine_enter(qemu_coroutine_create(bdrv_qed_open_entry, &qoc));
BDRV_POLL_WHILE(bs, qoc.ret == -EINPROGRESS);
}
BDRV_POLL_WHILE(bs, qoc.ret == -EINPROGRESS);
return qoc.ret;
}
static void bdrv_qed_refresh_limits(BlockDriverState *bs, Error **errp)
{
BDRVQEDState *s = bs->opaque;
bs->bl.pwrite_zeroes_alignment = s->header.cluster_size;
}
/* We have nothing to do for QED reopen, stubs just return
* success */
static int bdrv_qed_reopen_prepare(BDRVReopenState *state,
BlockReopenQueue *queue, Error **errp)
{
return 0;
}
static void bdrv_qed_close(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
bdrv_qed_detach_aio_context(bs);
/* Ensure writes reach stable storage */
bdrv_flush(bs->file->bs);
/* 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 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,
QemuOpts *opts, Error **errp)
{
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;
Error *local_err = NULL;
int ret = 0;
BlockBackend *blk;
ret = bdrv_create_file(filename, opts, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
return ret;
}
blk = blk_new_open(filename, NULL, NULL,
BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
&local_err);
if (blk == NULL) {
error_propagate(errp, local_err);
return -EIO;
}
blk_set_allow_write_beyond_eof(blk, true);
/* File must start empty and grow, check truncate is supported */
ret = blk_truncate(blk, 0, PREALLOC_MODE_OFF, errp);
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 = blk_pwrite(blk, 0, &le_header, sizeof(le_header), 0);
if (ret < 0) {
goto out;
}
ret = blk_pwrite(blk, sizeof(le_header), backing_file,
header.backing_filename_size, 0);
if (ret < 0) {
goto out;
}
l1_table = g_malloc0(l1_size);
ret = blk_pwrite(blk, header.l1_table_offset, l1_table, l1_size, 0);
if (ret < 0) {
goto out;
}
ret = 0; /* success */
out:
g_free(l1_table);
blk_unref(blk);
return ret;
}
static int coroutine_fn bdrv_qed_co_create_opts(const char *filename,
QemuOpts *opts,
Error **errp)
{
uint64_t image_size = 0;
uint32_t cluster_size = QED_DEFAULT_CLUSTER_SIZE;
uint32_t table_size = QED_DEFAULT_TABLE_SIZE;
char *backing_file = NULL;
char *backing_fmt = NULL;
int ret;
image_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
BDRV_SECTOR_SIZE);
backing_file = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
backing_fmt = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FMT);
cluster_size = qemu_opt_get_size_del(opts,
BLOCK_OPT_CLUSTER_SIZE,
QED_DEFAULT_CLUSTER_SIZE);
table_size = qemu_opt_get_size_del(opts, BLOCK_OPT_TABLE_SIZE,
QED_DEFAULT_TABLE_SIZE);
if (!qed_is_cluster_size_valid(cluster_size)) {
error_setg(errp, "QED cluster size must be within range [%u, %u] "
"and power of 2",
QED_MIN_CLUSTER_SIZE, QED_MAX_CLUSTER_SIZE);
ret = -EINVAL;
goto finish;
}
if (!qed_is_table_size_valid(table_size)) {
error_setg(errp, "QED table size must be within range [%u, %u] "
"and power of 2",
QED_MIN_TABLE_SIZE, QED_MAX_TABLE_SIZE);
ret = -EINVAL;
goto finish;
}
if (!qed_is_image_size_valid(image_size, cluster_size, table_size)) {
error_setg(errp, "QED image size must be a non-zero multiple of "
"cluster size and less than %" PRIu64 " bytes",
qed_max_image_size(cluster_size, table_size));
ret = -EINVAL;
goto finish;
}
ret = qed_create(filename, cluster_size, image_size, table_size,
backing_file, backing_fmt, opts, errp);
finish:
g_free(backing_file);
g_free(backing_fmt);
return ret;
}
static int coroutine_fn bdrv_qed_co_block_status(BlockDriverState *bs,
bool want_zero,
int64_t pos, int64_t bytes,
int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
BDRVQEDState *s = bs->opaque;
size_t len = MIN(bytes, SIZE_MAX);
int status;
QEDRequest request = { .l2_table = NULL };
uint64_t offset;
int ret;
qemu_co_mutex_lock(&s->table_lock);
ret = qed_find_cluster(s, &request, pos, &len, &offset);
*pnum = len;
switch (ret) {
case QED_CLUSTER_FOUND:
*map = offset | qed_offset_into_cluster(s, pos);
status = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
*file = bs->file->bs;
break;
case QED_CLUSTER_ZERO:
status = BDRV_BLOCK_ZERO;
break;
case QED_CLUSTER_L2:
case QED_CLUSTER_L1:
status = 0;
break;
default:
assert(ret < 0);
status = ret;
break;
}
qed_unref_l2_cache_entry(request.l2_table);
qemu_co_mutex_unlock(&s->table_lock);
return status;
}
static BDRVQEDState *acb_to_s(QEDAIOCB *acb)
{
return acb->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
* @backing_qiov: Possibly shortened copy of qiov, to be allocated here
* @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 int coroutine_fn qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
QEMUIOVector *qiov,
QEMUIOVector **backing_qiov)
{
uint64_t backing_length = 0;
size_t size;
int ret;
/* 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) {
int64_t l = bdrv_getlength(s->bs->backing->bs);
if (l < 0) {
return l;
}
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, 0, qiov->size);
}
/* Complete now if there are no backing file sectors to read */
if (pos >= backing_length) {
return 0;
}
/* If the read straddles the end of the backing file, shorten it */
size = MIN((uint64_t)backing_length - pos, qiov->size);
assert(*backing_qiov == NULL);
*backing_qiov = g_new(QEMUIOVector, 1);
qemu_iovec_init(*backing_qiov, qiov->niov);
qemu_iovec_concat(*backing_qiov, qiov, 0, size);
BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING_AIO);
ret = bdrv_co_preadv(s->bs->backing, pos, size, *backing_qiov, 0);
if (ret < 0) {
return ret;
}
return 0;
}
/**
* 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
*/
static int coroutine_fn qed_copy_from_backing_file(BDRVQEDState *s,
uint64_t pos, uint64_t len,
uint64_t offset)
{
QEMUIOVector qiov;
QEMUIOVector *backing_qiov = NULL;
struct iovec iov;
int ret;
/* Skip copy entirely if there is no work to do */
if (len == 0) {
return 0;
}
iov = (struct iovec) {
.iov_base = qemu_blockalign(s->bs, len),
.iov_len = len,
};
qemu_iovec_init_external(&qiov, &iov, 1);
ret = qed_read_backing_file(s, pos, &qiov, &backing_qiov);
if (backing_qiov) {
qemu_iovec_destroy(backing_qiov);
g_free(backing_qiov);
backing_qiov = NULL;
}
if (ret) {
goto out;
}
BLKDBG_EVENT(s->bs->file, BLKDBG_COW_WRITE);
ret = bdrv_co_pwritev(s->bs->file, offset, qiov.size, &qiov, 0);
if (ret < 0) {
goto out;
}
ret = 0;
out:
qemu_vfree(iov.iov_base);
return ret;
}
/**
* 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.
*
* Called with table_lock held.
*/
static void coroutine_fn 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;
}
}
}
/* Called with table_lock held. */
static void coroutine_fn qed_aio_complete(QEDAIOCB *acb)
{
BDRVQEDState *s = acb_to_s(acb);
/* Free resources */
qemu_iovec_destroy(&acb->cur_qiov);
qed_unref_l2_cache_entry(acb->request.l2_table);
/* Free the buffer we may have allocated for zero writes */
if (acb->flags & QED_AIOCB_ZERO) {
qemu_vfree(acb->qiov->iov[0].iov_base);
acb->qiov->iov[0].iov_base = NULL;
}
/* 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 == s->allocating_acb) {
s->allocating_acb = NULL;
if (!qemu_co_queue_empty(&s->allocating_write_reqs)) {
qemu_co_queue_next(&s->allocating_write_reqs);
} else if (s->header.features & QED_F_NEED_CHECK) {
qed_start_need_check_timer(s);
}
}
}
/**
* Update L1 table with new L2 table offset and write it out
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_write_l1_update(QEDAIOCB *acb)
{
BDRVQEDState *s = acb_to_s(acb);
CachedL2Table *l2_table = acb->request.l2_table;
uint64_t l2_offset = l2_table->offset;
int index, ret;
index = qed_l1_index(s, acb->cur_pos);
s->l1_table->offsets[index] = l2_table->offset;
ret = qed_write_l1_table(s, index, 1);
/* Commit the current L2 table to the cache */
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_offset);
assert(acb->request.l2_table != NULL);
return ret;
}
/**
* Update L2 table with new cluster offsets and write them out
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_write_l2_update(QEDAIOCB *acb, uint64_t offset)
{
BDRVQEDState *s = acb_to_s(acb);
bool need_alloc = acb->find_cluster_ret == QED_CLUSTER_L1;
int index, ret;
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,
offset);
if (need_alloc) {
/* Write out the whole new L2 table */
ret = qed_write_l2_table(s, &acb->request, 0, s->table_nelems, true);
if (ret) {
return ret;
}
return qed_aio_write_l1_update(acb);
} else {