From 71eed4cebed487a4f3c9f97aba83c611bbe22f8d Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Sun, 17 Jan 2021 00:46:59 +0300 Subject: [PATCH] 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 Reviewed-by: Max Reitz Message-Id: <20210116214705.822267-18-vsementsov@virtuozzo.com> Signed-off-by: Max Reitz --- block/backup.c | 187 ++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 120 insertions(+), 67 deletions(-) diff --git a/block/backup.c b/block/backup.c index 466608ee55..cc525d5544 100644 --- a/block/backup.c +++ b/block/backup.c @@ -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; - - if (job_is_cancelled(&job->common.job)) { - return true; - } - - /* - * 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); + 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); } - - 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; + + 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); + } - 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); + 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, -- 2.11.4.GIT