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backup: move to block-copy 

This brings async request handling and block-status driven chunk sizes
to backup out of the box, which improves backup performance.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-18-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2021-01-17 00:46:59 +03:00 committed by Max Reitz
parent 511e7d31bf
commit 71eed4cebe
1 changed files with 120 additions and 67 deletions
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187
block/backup.c
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@ -22,7 +22,6 @@
#include "block/block-copy.h"
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
#include "qemu/ratelimit.h"
#include "qemu/cutils.h"
#include "sysemu/block-backend.h"
#include "qemu/bitmap.h"
@ -44,41 +43,17 @@ typedef struct BackupBlockJob {
BlockdevOnError on_source_error;
BlockdevOnError on_target_error;
uint64_t len;
uint64_t bytes_read;
int64_t cluster_size;
BackupPerf perf;
BlockCopyState *bcs;
bool wait;
BlockCopyCallState *bg_bcs_call;
} BackupBlockJob;
static const BlockJobDriver backup_job_driver;
static void backup_progress_bytes_callback(int64_t bytes, void *opaque)
{
BackupBlockJob *s = opaque;
s->bytes_read += bytes;
}
static int coroutine_fn backup_do_cow(BackupBlockJob *job,
int64_t offset, uint64_t bytes,
bool *error_is_read)
{
int ret = 0;
int64_t start, end; /* bytes */
start = QEMU_ALIGN_DOWN(offset, job->cluster_size);
end = QEMU_ALIGN_UP(bytes + offset, job->cluster_size);
trace_backup_do_cow_enter(job, start, offset, bytes);
ret = block_copy(job->bcs, start, end - start, true, error_is_read);
trace_backup_do_cow_return(job, offset, bytes, ret);
return ret;
}
static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
{
BdrvDirtyBitmap *bm;
@ -158,53 +133,96 @@ static BlockErrorAction backup_error_action(BackupBlockJob *job,
}
}
static bool coroutine_fn yield_and_check(BackupBlockJob *job)
static void coroutine_fn backup_block_copy_callback(void *opaque)
{
uint64_t delay_ns;
BackupBlockJob *s = opaque;
if (job_is_cancelled(&job->common.job)) {
return true;
if (s->wait) {
s->wait = false;
aio_co_wake(s->common.job.co);
} else {
job_enter(&s->common.job);
}
/*
* We need to yield even for delay_ns = 0 so that bdrv_drain_all() can
* return. Without a yield, the VM would not reboot.
*/
delay_ns = block_job_ratelimit_get_delay(&job->common, job->bytes_read);
job->bytes_read = 0;
job_sleep_ns(&job->common.job, delay_ns);
if (job_is_cancelled(&job->common.job)) {
return true;
}
return false;
}
static int coroutine_fn backup_loop(BackupBlockJob *job)
{
bool error_is_read;
int64_t offset;
BdrvDirtyBitmapIter *bdbi;
BlockCopyCallState *s = NULL;
int ret = 0;
bool error_is_read;
BlockErrorAction act;
bdbi = bdrv_dirty_iter_new(block_copy_dirty_bitmap(job->bcs));
while ((offset = bdrv_dirty_iter_next(bdbi)) != -1) {
do {
if (yield_and_check(job)) {
goto out;
}
ret = backup_do_cow(job, offset, job->cluster_size, &error_is_read);
if (ret < 0 && backup_error_action(job, error_is_read, -ret) ==
BLOCK_ERROR_ACTION_REPORT)
{
goto out;
}
} while (ret < 0);
while (true) { /* retry loop */
job->bg_bcs_call = s = block_copy_async(job->bcs, 0,
QEMU_ALIGN_UP(job->len, job->cluster_size),
job->perf.max_workers, job->perf.max_chunk,
backup_block_copy_callback, job);
while (!block_copy_call_finished(s) &&
!job_is_cancelled(&job->common.job))
{
job_yield(&job->common.job);
}
if (!block_copy_call_finished(s)) {
assert(job_is_cancelled(&job->common.job));
/*
* Note that we can't use job_yield() here, as it doesn't work for
* cancelled job.
*/
block_copy_call_cancel(s);
job->wait = true;
qemu_coroutine_yield();
assert(block_copy_call_finished(s));
ret = 0;
goto out;
}
if (job_is_cancelled(&job->common.job) ||
block_copy_call_succeeded(s))
{
ret = 0;
goto out;
}
if (block_copy_call_cancelled(s)) {
/*
* Job is not cancelled but only block-copy call. This is possible
* after job pause. Now the pause is finished, start new block-copy
* iteration.
*/
block_copy_call_free(s);
continue;
}
/* The only remaining case is failed block-copy call. */
assert(block_copy_call_failed(s));
ret = block_copy_call_status(s, &error_is_read);
act = backup_error_action(job, error_is_read, -ret);
switch (act) {
case BLOCK_ERROR_ACTION_REPORT:
goto out;
case BLOCK_ERROR_ACTION_STOP:
/*
* Go to pause prior to starting new block-copy call on the next
* iteration.
*/
job_pause_point(&job->common.job);
break;
case BLOCK_ERROR_ACTION_IGNORE:
/* Proceed to new block-copy call to retry. */
break;
default:
abort();
}
block_copy_call_free(s);
}
out:
bdrv_dirty_iter_free(bdbi);
out:
block_copy_call_free(s);
job->bg_bcs_call = NULL;
return ret;
}
@ -245,7 +263,13 @@ static int coroutine_fn backup_run(Job *job, Error **errp)
int64_t count;
for (offset = 0; offset < s->len; ) {
if (yield_and_check(s)) {
if (job_is_cancelled(job)) {
return -ECANCELED;
}
job_pause_point(job);
if (job_is_cancelled(job)) {
return -ECANCELED;
}
@ -278,6 +302,33 @@ static int coroutine_fn backup_run(Job *job, Error **errp)
return 0;
}
static void coroutine_fn backup_pause(Job *job)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
if (s->bg_bcs_call && !block_copy_call_finished(s->bg_bcs_call)) {
block_copy_call_cancel(s->bg_bcs_call);
s->wait = true;
qemu_coroutine_yield();
}
}
static void coroutine_fn backup_set_speed(BlockJob *job, int64_t speed)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common);
/*
* block_job_set_speed() is called first from block_job_create(), when we
* don't yet have s->bcs.
*/
if (s->bcs) {
block_copy_set_speed(s->bcs, speed);
if (s->bg_bcs_call) {
block_copy_kick(s->bg_bcs_call);
}
}
}
static const BlockJobDriver backup_job_driver = {
.job_driver = {
.instance_size = sizeof(BackupBlockJob),
@ -288,7 +339,9 @@ static const BlockJobDriver backup_job_driver = {
.commit = backup_commit,
.abort = backup_abort,
.clean = backup_clean,
}
.pause = backup_pause,
},
.set_speed = backup_set_speed,
};
static int64_t backup_calculate_cluster_size(BlockDriverState *target,
@ -485,8 +538,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
job->len = len;
job->perf = *perf;
block_copy_set_progress_callback(bcs, backup_progress_bytes_callback, job);
block_copy_set_progress_meter(bcs, &job->common.job.progress);
block_copy_set_speed(bcs, speed);
/* Required permissions are already taken by backup-top target */
block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,