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qemu/block/block-copy.c
Kevin Wolf abaf8b750b block: Mark bdrv_co_pwrite_zeroes() and callers GRAPH_RDLOCK 
This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_co_pwrite_zeroes() need to hold a reader lock for the graph.

For some places, we know that they will hold the lock, but we don't have
the GRAPH_RDLOCK annotations yet. In this case, add assume_graph_lock()
with a FIXME comment. These places will be removed once everything is
properly annotated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230203152202.49054-10-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-02-23 19:49:14 +01:00

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/*
* block_copy API
*
* Copyright (C) 2013 Proxmox Server Solutions
* Copyright (c) 2019 Virtuozzo International GmbH.
*
* Authors:
* Dietmar Maurer (dietmar@proxmox.com)
* Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "trace.h"
#include "qapi/error.h"
#include "block/block-copy.h"
#include "block/block_int-io.h"
#include "block/dirty-bitmap.h"
#include "block/reqlist.h"
#include "sysemu/block-backend.h"
#include "qemu/units.h"
#include "qemu/co-shared-resource.h"
#include "qemu/coroutine.h"
#include "qemu/ratelimit.h"
#include "block/aio_task.h"
#include "qemu/error-report.h"
#include "qemu/memalign.h"
#define BLOCK_COPY_MAX_COPY_RANGE (16 * MiB)
#define BLOCK_COPY_MAX_BUFFER (1 * MiB)
#define BLOCK_COPY_MAX_MEM (128 * MiB)
#define BLOCK_COPY_MAX_WORKERS 64
#define BLOCK_COPY_SLICE_TIME 100000000ULL /* ns */
#define BLOCK_COPY_CLUSTER_SIZE_DEFAULT (1 << 16)
typedef enum {
COPY_READ_WRITE_CLUSTER,
COPY_READ_WRITE,
COPY_WRITE_ZEROES,
COPY_RANGE_SMALL,
COPY_RANGE_FULL
} BlockCopyMethod;
static coroutine_fn int block_copy_task_entry(AioTask *task);
typedef struct BlockCopyCallState {
/* Fields initialized in block_copy_async() and never changed. */
BlockCopyState *s;
int64_t offset;
int64_t bytes;
int max_workers;
int64_t max_chunk;
bool ignore_ratelimit;
BlockCopyAsyncCallbackFunc cb;
void *cb_opaque;
/* Coroutine where async block-copy is running */
Coroutine *co;
/* Fields whose state changes throughout the execution */
bool finished; /* atomic */
QemuCoSleep sleep; /* TODO: protect API with a lock */
bool cancelled; /* atomic */
/* To reference all call states from BlockCopyState */
QLIST_ENTRY(BlockCopyCallState) list;
/*
* Fields that report information about return values and erros.
* Protected by lock in BlockCopyState.
*/
bool error_is_read;
/*
* @ret is set concurrently by tasks under mutex. Only set once by first
* failed task (and untouched if no task failed).
* After finishing (call_state->finished is true), it is not modified
* anymore and may be safely read without mutex.
*/
int ret;
} BlockCopyCallState;
typedef struct BlockCopyTask {
AioTask task;
/*
* Fields initialized in block_copy_task_create()
* and never changed.
*/
BlockCopyState *s;
BlockCopyCallState *call_state;
/*
* @method can also be set again in the while loop of
* block_copy_dirty_clusters(), but it is never accessed concurrently
* because the only other function that reads it is
* block_copy_task_entry() and it is invoked afterwards in the same
* iteration.
*/
BlockCopyMethod method;
/*
* Generally, req is protected by lock in BlockCopyState, Still req.offset
* is only set on task creation, so may be read concurrently after creation.
* req.bytes is changed at most once, and need only protecting the case of
* parallel read while updating @bytes value in block_copy_task_shrink().
*/
BlockReq req;
} BlockCopyTask;
static int64_t task_end(BlockCopyTask *task)
{
return task->req.offset + task->req.bytes;
}
typedef struct BlockCopyState {
/*
* BdrvChild objects are not owned or managed by block-copy. They are
* provided by block-copy user and user is responsible for appropriate
* permissions on these children.
*/
BdrvChild *source;
BdrvChild *target;
/*
* Fields initialized in block_copy_state_new()
* and never changed.
*/
int64_t cluster_size;
int64_t max_transfer;
uint64_t len;
BdrvRequestFlags write_flags;
/*
* Fields whose state changes throughout the execution
* Protected by lock.
*/
CoMutex lock;
int64_t in_flight_bytes;
BlockCopyMethod method;
BlockReqList reqs;
QLIST_HEAD(, BlockCopyCallState) calls;
/*
* skip_unallocated:
*
* Used by sync=top jobs, which first scan the source node for unallocated
* areas and clear them in the copy_bitmap. During this process, the bitmap
* is thus not fully initialized: It may still have bits set for areas that
* are unallocated and should actually not be copied.
*
* This is indicated by skip_unallocated.
*
* In this case, block_copy() will query the source’s allocation status,
* skip unallocated regions, clear them in the copy_bitmap, and invoke
* block_copy_reset_unallocated() every time it does.
*/
bool skip_unallocated; /* atomic */
/* State fields that use a thread-safe API */
BdrvDirtyBitmap *copy_bitmap;
ProgressMeter *progress;
SharedResource *mem;
RateLimit rate_limit;
} BlockCopyState;
/* Called with lock held */
static int64_t block_copy_chunk_size(BlockCopyState *s)
{
switch (s->method) {
case COPY_READ_WRITE_CLUSTER:
return s->cluster_size;
case COPY_READ_WRITE:
case COPY_RANGE_SMALL:
return MIN(MAX(s->cluster_size, BLOCK_COPY_MAX_BUFFER),
s->max_transfer);
case COPY_RANGE_FULL:
return MIN(MAX(s->cluster_size, BLOCK_COPY_MAX_COPY_RANGE),
s->max_transfer);
default:
/* Cannot have COPY_WRITE_ZEROES here. */
abort();
}
}
/*
* Search for the first dirty area in offset/bytes range and create task at
* the beginning of it.
*/
static coroutine_fn BlockCopyTask *
block_copy_task_create(BlockCopyState *s, BlockCopyCallState *call_state,
int64_t offset, int64_t bytes)
{
BlockCopyTask *task;
int64_t max_chunk;
QEMU_LOCK_GUARD(&s->lock);
max_chunk = MIN_NON_ZERO(block_copy_chunk_size(s), call_state->max_chunk);
if (!bdrv_dirty_bitmap_next_dirty_area(s->copy_bitmap,
offset, offset + bytes,
max_chunk, &offset, &bytes))
{
return NULL;
}
assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
bytes = QEMU_ALIGN_UP(bytes, s->cluster_size);
/* region is dirty, so no existent tasks possible in it */
assert(!reqlist_find_conflict(&s->reqs, offset, bytes));
bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, bytes);
s->in_flight_bytes += bytes;
task = g_new(BlockCopyTask, 1);
*task = (BlockCopyTask) {
.task.func = block_copy_task_entry,
.s = s,
.call_state = call_state,
.method = s->method,
};
reqlist_init_req(&s->reqs, &task->req, offset, bytes);
return task;
}
/*
* block_copy_task_shrink
*
* Drop the tail of the task to be handled later. Set dirty bits back and
* wake up all tasks waiting for us (may be some of them are not intersecting
* with shrunk task)
*/
static void coroutine_fn block_copy_task_shrink(BlockCopyTask *task,
int64_t new_bytes)
{
QEMU_LOCK_GUARD(&task->s->lock);
if (new_bytes == task->req.bytes) {
return;
}
assert(new_bytes > 0 && new_bytes < task->req.bytes);
task->s->in_flight_bytes -= task->req.bytes - new_bytes;
bdrv_set_dirty_bitmap(task->s->copy_bitmap,
task->req.offset + new_bytes,
task->req.bytes - new_bytes);
reqlist_shrink_req(&task->req, new_bytes);
}
static void coroutine_fn block_copy_task_end(BlockCopyTask *task, int ret)
{
QEMU_LOCK_GUARD(&task->s->lock);
task->s->in_flight_bytes -= task->req.bytes;
if (ret < 0) {
bdrv_set_dirty_bitmap(task->s->copy_bitmap, task->req.offset,
task->req.bytes);
}
if (task->s->progress) {
progress_set_remaining(task->s->progress,
bdrv_get_dirty_count(task->s->copy_bitmap) +
task->s->in_flight_bytes);
}
reqlist_remove_req(&task->req);
}
void block_copy_state_free(BlockCopyState *s)
{
if (!s) {
return;
}
ratelimit_destroy(&s->rate_limit);
bdrv_release_dirty_bitmap(s->copy_bitmap);
shres_destroy(s->mem);
g_free(s);
}
static uint32_t block_copy_max_transfer(BdrvChild *source, BdrvChild *target)
{
return MIN_NON_ZERO(INT_MAX,
MIN_NON_ZERO(source->bs->bl.max_transfer,
target->bs->bl.max_transfer));
}
void block_copy_set_copy_opts(BlockCopyState *s, bool use_copy_range,
bool compress)
{
/* Keep BDRV_REQ_SERIALISING set (or not set) in block_copy_state_new() */
s->write_flags = (s->write_flags & BDRV_REQ_SERIALISING) |
(compress ? BDRV_REQ_WRITE_COMPRESSED : 0);
if (s->max_transfer < s->cluster_size) {
/*
* copy_range does not respect max_transfer. We don't want to bother
* with requests smaller than block-copy cluster size, so fallback to
* buffered copying (read and write respect max_transfer on their
* behalf).
*/
s->method = COPY_READ_WRITE_CLUSTER;
} else if (compress) {
/* Compression supports only cluster-size writes and no copy-range. */
s->method = COPY_READ_WRITE_CLUSTER;
} else {
/*
* If copy range enabled, start with COPY_RANGE_SMALL, until first
* successful copy_range (look at block_copy_do_copy).
*/
s->method = use_copy_range ? COPY_RANGE_SMALL : COPY_READ_WRITE;
}
}
static int64_t block_copy_calculate_cluster_size(BlockDriverState *target,
Error **errp)
{
int ret;
BlockDriverInfo bdi;
bool target_does_cow = bdrv_backing_chain_next(target);
/*
* If there is no backing file on the target, we cannot rely on COW if our
* backup cluster size is smaller than the target cluster size. Even for
* targets with a backing file, try to avoid COW if possible.
*/
ret = bdrv_get_info(target, &bdi);
if (ret == -ENOTSUP && !target_does_cow) {
/* Cluster size is not defined */
warn_report("The target block device doesn't provide "
"information about the block size and it doesn't have a "
"backing file. The default block size of %u bytes is "
"used. If the actual block size of the target exceeds "
"this default, the backup may be unusable",
BLOCK_COPY_CLUSTER_SIZE_DEFAULT);
return BLOCK_COPY_CLUSTER_SIZE_DEFAULT;
} else if (ret < 0 && !target_does_cow) {
error_setg_errno(errp, -ret,
"Couldn't determine the cluster size of the target image, "
"which has no backing file");
error_append_hint(errp,
"Aborting, since this may create an unusable destination image\n");
return ret;
} else if (ret < 0 && target_does_cow) {
/* Not fatal; just trudge on ahead. */
return BLOCK_COPY_CLUSTER_SIZE_DEFAULT;
}
return MAX(BLOCK_COPY_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
}
BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
const BdrvDirtyBitmap *bitmap,
Error **errp)
{
ERRP_GUARD();
BlockCopyState *s;
int64_t cluster_size;
BdrvDirtyBitmap *copy_bitmap;
bool is_fleecing;
cluster_size = block_copy_calculate_cluster_size(target->bs, errp);
if (cluster_size < 0) {
return NULL;
}
copy_bitmap = bdrv_create_dirty_bitmap(source->bs, cluster_size, NULL,
errp);
if (!copy_bitmap) {
return NULL;
}
bdrv_disable_dirty_bitmap(copy_bitmap);
if (bitmap) {
if (!bdrv_merge_dirty_bitmap(copy_bitmap, bitmap, NULL, errp)) {
error_prepend(errp, "Failed to merge bitmap '%s' to internal "
"copy-bitmap: ", bdrv_dirty_bitmap_name(bitmap));
bdrv_release_dirty_bitmap(copy_bitmap);
return NULL;
}
} else {
bdrv_set_dirty_bitmap(copy_bitmap, 0,
bdrv_dirty_bitmap_size(copy_bitmap));
}
/*
* If source is in backing chain of target assume that target is going to be
* used for "image fleecing", i.e. it should represent a kind of snapshot of
* source at backup-start point in time. And target is going to be read by
* somebody (for example, used as NBD export) during backup job.
*
* In this case, we need to add BDRV_REQ_SERIALISING write flag to avoid
* intersection of backup writes and third party reads from target,
* otherwise reading from target we may occasionally read already updated by
* guest data.
*
* For more information see commit f8d59dfb40bb and test
* tests/qemu-iotests/222
*/
is_fleecing = bdrv_chain_contains(target->bs, source->bs);
s = g_new(BlockCopyState, 1);
*s = (BlockCopyState) {
.source = source,
.target = target,
.copy_bitmap = copy_bitmap,
.cluster_size = cluster_size,
.len = bdrv_dirty_bitmap_size(copy_bitmap),
.write_flags = (is_fleecing ? BDRV_REQ_SERIALISING : 0),
.mem = shres_create(BLOCK_COPY_MAX_MEM),
.max_transfer = QEMU_ALIGN_DOWN(
block_copy_max_transfer(source, target),
cluster_size),
};
block_copy_set_copy_opts(s, false, false);
ratelimit_init(&s->rate_limit);
qemu_co_mutex_init(&s->lock);
QLIST_INIT(&s->reqs);
QLIST_INIT(&s->calls);
return s;
}
/* Only set before running the job, no need for locking. */
void block_copy_set_progress_meter(BlockCopyState *s, ProgressMeter *pm)
{
s->progress = pm;
}
/*
* Takes ownership of @task
*
* If pool is NULL directly run the task, otherwise schedule it into the pool.
*
* Returns: task.func return code if pool is NULL
* otherwise -ECANCELED if pool status is bad
* otherwise 0 (successfully scheduled)
*/
static coroutine_fn int block_copy_task_run(AioTaskPool *pool,
BlockCopyTask *task)
{
if (!pool) {
int ret = task->task.func(&task->task);
g_free(task);
return ret;
}
aio_task_pool_wait_slot(pool);
if (aio_task_pool_status(pool) < 0) {
co_put_to_shres(task->s->mem, task->req.bytes);
block_copy_task_end(task, -ECANCELED);
g_free(task);
return -ECANCELED;
}
aio_task_pool_start_task(pool, &task->task);
return 0;
}
/*
* block_copy_do_copy
*
* Do copy of cluster-aligned chunk. Requested region is allowed to exceed
* s->len only to cover last cluster when s->len is not aligned to clusters.
*
* No sync here: nor bitmap neighter intersecting requests handling, only copy.
*
* @method is an in-out argument, so that copy_range can be either extended to
* a full-size buffer or disabled if the copy_range attempt fails. The output
* value of @method should be used for subsequent tasks.
* Returns 0 on success.
*/
static int coroutine_fn GRAPH_RDLOCK
block_copy_do_copy(BlockCopyState *s, int64_t offset, int64_t bytes,
BlockCopyMethod *method, bool *error_is_read)
{
int ret;
int64_t nbytes = MIN(offset + bytes, s->len) - offset;
void *bounce_buffer = NULL;
assert(offset >= 0 && bytes > 0 && INT64_MAX - offset >= bytes);
assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
assert(offset < s->len);
assert(offset + bytes <= s->len ||
offset + bytes == QEMU_ALIGN_UP(s->len, s->cluster_size));
assert(nbytes < INT_MAX);
switch (*method) {
case COPY_WRITE_ZEROES:
ret = bdrv_co_pwrite_zeroes(s->target, offset, nbytes, s->write_flags &
~BDRV_REQ_WRITE_COMPRESSED);
if (ret < 0) {
trace_block_copy_write_zeroes_fail(s, offset, ret);
*error_is_read = false;
}
return ret;
case COPY_RANGE_SMALL:
case COPY_RANGE_FULL:
ret = bdrv_co_copy_range(s->source, offset, s->target, offset, nbytes,
0, s->write_flags);
if (ret >= 0) {
/* Successful copy-range, increase chunk size. */
*method = COPY_RANGE_FULL;
return 0;
}
trace_block_copy_copy_range_fail(s, offset, ret);
*method = COPY_READ_WRITE;
/* Fall through to read+write with allocated buffer */
case COPY_READ_WRITE_CLUSTER:
case COPY_READ_WRITE:
/*
* In case of failed copy_range request above, we may proceed with
* buffered request larger than BLOCK_COPY_MAX_BUFFER.
* Still, further requests will be properly limited, so don't care too
* much. Moreover the most likely case (copy_range is unsupported for
* the configuration, so the very first copy_range request fails)
* is handled by setting large copy_size only after first successful
* copy_range.
*/
bounce_buffer = qemu_blockalign(s->source->bs, nbytes);
ret = bdrv_co_pread(s->source, offset, nbytes, bounce_buffer, 0);
if (ret < 0) {
trace_block_copy_read_fail(s, offset, ret);
*error_is_read = true;
goto out;
}
ret = bdrv_co_pwrite(s->target, offset, nbytes, bounce_buffer,
s->write_flags);
if (ret < 0) {
trace_block_copy_write_fail(s, offset, ret);
*error_is_read = false;
goto out;
}
out:
qemu_vfree(bounce_buffer);
break;
default:
abort();
}
return ret;
}
static coroutine_fn int block_copy_task_entry(AioTask *task)
{
BlockCopyTask *t = container_of(task, BlockCopyTask, task);
BlockCopyState *s = t->s;
bool error_is_read = false;
BlockCopyMethod method = t->method;
int ret;
WITH_GRAPH_RDLOCK_GUARD() {
ret = block_copy_do_copy(s, t->req.offset, t->req.bytes, &method,
&error_is_read);
}
WITH_QEMU_LOCK_GUARD(&s->lock) {
if (s->method == t->method) {
s->method = method;
}
if (ret < 0) {
if (!t->call_state->ret) {
t->call_state->ret = ret;
t->call_state->error_is_read = error_is_read;
}
} else if (s->progress) {
progress_work_done(s->progress, t->req.bytes);
}
}
co_put_to_shres(s->mem, t->req.bytes);
block_copy_task_end(t, ret);
return ret;
}
static coroutine_fn GRAPH_RDLOCK
int block_copy_block_status(BlockCopyState *s, int64_t offset, int64_t bytes,
int64_t *pnum)
{
int64_t num;
BlockDriverState *base;
int ret;
if (qatomic_read(&s->skip_unallocated)) {
base = bdrv_backing_chain_next(s->source->bs);
} else {
base = NULL;
}
ret = bdrv_co_block_status_above(s->source->bs, base, offset, bytes, &num,
NULL, NULL);
if (ret < 0 || num < s->cluster_size) {
/*
* On error or if failed to obtain large enough chunk just fallback to
* copy one cluster.
*/
num = s->cluster_size;
ret = BDRV_BLOCK_ALLOCATED | BDRV_BLOCK_DATA;
} else if (offset + num == s->len) {
num = QEMU_ALIGN_UP(num, s->cluster_size);
} else {
num = QEMU_ALIGN_DOWN(num, s->cluster_size);
}
*pnum = num;
return ret;
}
/*
* Check if the cluster starting at offset is allocated or not.
* return via pnum the number of contiguous clusters sharing this allocation.
*/
static int coroutine_fn GRAPH_RDLOCK
block_copy_is_cluster_allocated(BlockCopyState *s, int64_t offset,
int64_t *pnum)
{
BlockDriverState *bs = s->source->bs;
int64_t count, total_count = 0;
int64_t bytes = s->len - offset;
int ret;
assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
while (true) {
/* protected in backup_run() */
ret = bdrv_co_is_allocated(bs, offset, bytes, &count);
if (ret < 0) {
return ret;
}
total_count += count;
if (ret || count == 0) {
/*
* ret: partial segment(s) are considered allocated.
* otherwise: unallocated tail is treated as an entire segment.
*/
*pnum = DIV_ROUND_UP(total_count, s->cluster_size);
return ret;
}
/* Unallocated segment(s) with uncertain following segment(s) */
if (total_count >= s->cluster_size) {
*pnum = total_count / s->cluster_size;
return 0;
}
offset += count;
bytes -= count;
}
}
void block_copy_reset(BlockCopyState *s, int64_t offset, int64_t bytes)
{
QEMU_LOCK_GUARD(&s->lock);
bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, bytes);
if (s->progress) {
progress_set_remaining(s->progress,
bdrv_get_dirty_count(s->copy_bitmap) +
s->in_flight_bytes);
}
}
/*
* Reset bits in copy_bitmap starting at offset if they represent unallocated
* data in the image. May reset subsequent contiguous bits.
* @return 0 when the cluster at @offset was unallocated,
* 1 otherwise, and -ret on error.
*/
int64_t coroutine_fn block_copy_reset_unallocated(BlockCopyState *s,
int64_t offset,
int64_t *count)
{
int ret;
int64_t clusters, bytes;
ret = block_copy_is_cluster_allocated(s, offset, &clusters);
if (ret < 0) {
return ret;
}
bytes = clusters * s->cluster_size;
if (!ret) {
block_copy_reset(s, offset, bytes);
}
*count = bytes;
return ret;
}
/*
* block_copy_dirty_clusters
*
* Copy dirty clusters in @offset/@bytes range.
* Returns 1 if dirty clusters found and successfully copied, 0 if no dirty
* clusters found and -errno on failure.
*/
static int coroutine_fn GRAPH_RDLOCK
block_copy_dirty_clusters(BlockCopyCallState *call_state)
{
BlockCopyState *s = call_state->s;
int64_t offset = call_state->offset;
int64_t bytes = call_state->bytes;
int ret = 0;
bool found_dirty = false;
int64_t end = offset + bytes;
AioTaskPool *aio = NULL;
/*
* block_copy() user is responsible for keeping source and target in same
* aio context
*/
assert(bdrv_get_aio_context(s->source->bs) ==
bdrv_get_aio_context(s->target->bs));
assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
while (bytes && aio_task_pool_status(aio) == 0 &&
!qatomic_read(&call_state->cancelled)) {
BlockCopyTask *task;
int64_t status_bytes;
task = block_copy_task_create(s, call_state, offset, bytes);
if (!task) {
/* No more dirty bits in the bitmap */
trace_block_copy_skip_range(s, offset, bytes);
break;
}
if (task->req.offset > offset) {
trace_block_copy_skip_range(s, offset, task->req.offset - offset);
}
found_dirty = true;
ret = block_copy_block_status(s, task->req.offset, task->req.bytes,
&status_bytes);
assert(ret >= 0); /* never fail */
if (status_bytes < task->req.bytes) {
block_copy_task_shrink(task, status_bytes);
}
if (qatomic_read(&s->skip_unallocated) &&
!(ret & BDRV_BLOCK_ALLOCATED)) {
block_copy_task_end(task, 0);
trace_block_copy_skip_range(s, task->req.offset, task->req.bytes);
offset = task_end(task);
bytes = end - offset;
g_free(task);
continue;
}
if (ret & BDRV_BLOCK_ZERO) {
task->method = COPY_WRITE_ZEROES;
}
if (!call_state->ignore_ratelimit) {
uint64_t ns = ratelimit_calculate_delay(&s->rate_limit, 0);
if (ns > 0) {
block_copy_task_end(task, -EAGAIN);
g_free(task);
qemu_co_sleep_ns_wakeable(&call_state->sleep,
QEMU_CLOCK_REALTIME, ns);
continue;
}
}
ratelimit_calculate_delay(&s->rate_limit, task->req.bytes);
trace_block_copy_process(s, task->req.offset);
co_get_from_shres(s->mem, task->req.bytes);
offset = task_end(task);
bytes = end - offset;
if (!aio && bytes) {
aio = aio_task_pool_new(call_state->max_workers);
}
ret = block_copy_task_run(aio, task);
if (ret < 0) {
goto out;
}
}
out:
if (aio) {
aio_task_pool_wait_all(aio);
/*
* We are not really interested in -ECANCELED returned from
* block_copy_task_run. If it fails, it means some task already failed
* for real reason, let's return first failure.
* Still, assert that we don't rewrite failure by success.
*
* Note: ret may be positive here because of block-status result.
*/
assert(ret >= 0 || aio_task_pool_status(aio) < 0);
ret = aio_task_pool_status(aio);
aio_task_pool_free(aio);
}
return ret < 0 ? ret : found_dirty;
}
void block_copy_kick(BlockCopyCallState *call_state)
{
qemu_co_sleep_wake(&call_state->sleep);
}
/*
* block_copy_common
*
* Copy requested region, accordingly to dirty bitmap.
* Collaborate with parallel block_copy requests: if they succeed it will help
* us. If they fail, we will retry not-copied regions. So, if we return error,
* it means that some I/O operation failed in context of _this_ block_copy call,
* not some parallel operation.
*/
static int coroutine_fn GRAPH_RDLOCK
block_copy_common(BlockCopyCallState *call_state)
{
int ret;
BlockCopyState *s = call_state->s;
qemu_co_mutex_lock(&s->lock);
QLIST_INSERT_HEAD(&s->calls, call_state, list);
qemu_co_mutex_unlock(&s->lock);
do {
ret = block_copy_dirty_clusters(call_state);
if (ret == 0 && !qatomic_read(&call_state->cancelled)) {
WITH_QEMU_LOCK_GUARD(&s->lock) {
/*
* Check that there is no task we still need to
* wait to complete
*/
ret = reqlist_wait_one(&s->reqs, call_state->offset,
call_state->bytes, &s->lock);
if (ret == 0) {
/*
* No pending tasks, but check again the bitmap in this
* same critical section, since a task might have failed
* between this and the critical section in
* block_copy_dirty_clusters().
*
* reqlist_wait_one return value 0 also means that it
* didn't release the lock. So, we are still in the same
* critical section, not interrupted by any concurrent
* access to state.
*/
ret = bdrv_dirty_bitmap_next_dirty(s->copy_bitmap,
call_state->offset,
call_state->bytes) >= 0;
}
}
}
/*
* We retry in two cases:
* 1. Some progress done
* Something was copied, which means that there were yield points
* and some new dirty bits may have appeared (due to failed parallel
* block-copy requests).
* 2. We have waited for some intersecting block-copy request
* It may have failed and produced new dirty bits.
*/
} while (ret > 0 && !qatomic_read(&call_state->cancelled));
qatomic_store_release(&call_state->finished, true);
if (call_state->cb) {
call_state->cb(call_state->cb_opaque);
}
qemu_co_mutex_lock(&s->lock);
QLIST_REMOVE(call_state, list);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
static void coroutine_fn block_copy_async_co_entry(void *opaque)
{
GRAPH_RDLOCK_GUARD();
block_copy_common(opaque);
}
int coroutine_fn block_copy(BlockCopyState *s, int64_t start, int64_t bytes,
bool ignore_ratelimit, uint64_t timeout_ns,
BlockCopyAsyncCallbackFunc cb,
void *cb_opaque)
{
int ret;
BlockCopyCallState *call_state = g_new(BlockCopyCallState, 1);
*call_state = (BlockCopyCallState) {
.s = s,
.offset = start,
.bytes = bytes,
.ignore_ratelimit = ignore_ratelimit,
.max_workers = BLOCK_COPY_MAX_WORKERS,
.cb = cb,
.cb_opaque = cb_opaque,
};
ret = qemu_co_timeout(block_copy_async_co_entry, call_state, timeout_ns,
g_free);
if (ret < 0) {
assert(ret == -ETIMEDOUT);
block_copy_call_cancel(call_state);
/* call_state will be freed by running coroutine. */
return ret;
}
ret = call_state->ret;
g_free(call_state);
return ret;
}
BlockCopyCallState *block_copy_async(BlockCopyState *s,
int64_t offset, int64_t bytes,
int max_workers, int64_t max_chunk,
BlockCopyAsyncCallbackFunc cb,
void *cb_opaque)
{
BlockCopyCallState *call_state = g_new(BlockCopyCallState, 1);
*call_state = (BlockCopyCallState) {
.s = s,
.offset = offset,
.bytes = bytes,
.max_workers = max_workers,
.max_chunk = max_chunk,
.cb = cb,
.cb_opaque = cb_opaque,
.co = qemu_coroutine_create(block_copy_async_co_entry, call_state),
};
qemu_coroutine_enter(call_state->co);
return call_state;
}
void block_copy_call_free(BlockCopyCallState *call_state)
{
if (!call_state) {
return;
}
assert(qatomic_read(&call_state->finished));
g_free(call_state);
}
bool block_copy_call_finished(BlockCopyCallState *call_state)
{
return qatomic_read(&call_state->finished);
}
bool block_copy_call_succeeded(BlockCopyCallState *call_state)
{
return qatomic_load_acquire(&call_state->finished) &&
!qatomic_read(&call_state->cancelled) &&
call_state->ret == 0;
}
bool block_copy_call_failed(BlockCopyCallState *call_state)
{
return qatomic_load_acquire(&call_state->finished) &&
!qatomic_read(&call_state->cancelled) &&
call_state->ret < 0;
}
bool block_copy_call_cancelled(BlockCopyCallState *call_state)
{
return qatomic_read(&call_state->cancelled);
}
int block_copy_call_status(BlockCopyCallState *call_state, bool *error_is_read)
{
assert(qatomic_load_acquire(&call_state->finished));
if (error_is_read) {
*error_is_read = call_state->error_is_read;
}
return call_state->ret;
}
/*
* Note that cancelling and finishing are racy.
* User can cancel a block-copy that is already finished.
*/
void block_copy_call_cancel(BlockCopyCallState *call_state)
{
qatomic_set(&call_state->cancelled, true);
block_copy_kick(call_state);
}
BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s)
{
return s->copy_bitmap;
}
int64_t block_copy_cluster_size(BlockCopyState *s)
{
return s->cluster_size;
}
void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip)
{
qatomic_set(&s->skip_unallocated, skip);
}
void block_copy_set_speed(BlockCopyState *s, uint64_t speed)
{
ratelimit_set_speed(&s->rate_limit, speed, BLOCK_COPY_SLICE_TIME);
/*
* Note: it's good to kick all call states from here, but it should be done
* only from a coroutine, to not crash if s->calls list changed while
* entering one call. So for now, the only user of this function kicks its
* only one call_state by hand.
*/
}
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