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pve-qemu-qoup/debian/patches/pve/0037-PVE-Backup-Use-a-transaction-to-synchronize-job-stat.patch
Fabian Ebner 27199bd753 backup: add patch to initialize bcs bitmap early enough for PBS 
This is necessary for multi-disk backups where not all jobs are
immediately started after they are created. QEMU commit
06e0a9c16405c0a4c1eca33cf286cc04c42066a2 did already part of the work,
ensuring that new writes after job creation don't pass through to the
backup, but not yet for the MIRROR_SYNC_MODE_BITMAP case which is used
for PBS.

Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
2022-03-03 11:37:17 +01:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Stefan Reiter <s.reiter@proxmox.com>
Date: Thu, 20 Aug 2020 14:25:00 +0200
Subject: [PATCH] PVE-Backup: Use a transaction to synchronize job states
By using a JobTxn, we can sync dirty bitmaps only when *all* jobs were
successful - meaning we don't need to remove them when the backup fails,
since QEMU's BITMAP_SYNC_MODE_ON_SUCCESS will now handle that for us.
To keep the rate-limiting and IO impact from before, we use a sequential
transaction, so drives will still be backed up one after the other.
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
[add new force parameter to job_cancel_sync calls]
Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
---
pve-backup.c | 169 +++++++++++++++------------------------------------
1 file changed, 50 insertions(+), 119 deletions(-)
diff --git a/pve-backup.c b/pve-backup.c
index f90abaa50a..63c686463f 100644
--- a/pve-backup.c
+++ b/pve-backup.c
@@ -52,6 +52,7 @@ static struct PVEBackupState {
VmaWriter *vmaw;
ProxmoxBackupHandle *pbs;
GList *di_list;
+ JobTxn *txn;
QemuMutex backup_mutex;
CoMutex dump_callback_mutex;
} backup_state;
@@ -71,32 +72,12 @@ typedef struct PVEBackupDevInfo {
size_t size;
uint64_t block_size;
uint8_t dev_id;
- bool completed;
char targetfile[PATH_MAX];
BdrvDirtyBitmap *bitmap;
BlockDriverState *target;
+ BlockJob *job;
} PVEBackupDevInfo;
-static void pvebackup_run_next_job(void);
-
-static BlockJob *
-lookup_active_block_job(PVEBackupDevInfo *di)
-{
- if (!di->completed && di->bs) {
- for (BlockJob *job = block_job_next(NULL); job; job = block_job_next(job)) {
- if (job->job.driver->job_type != JOB_TYPE_BACKUP) {
- continue;
- }
-
- BackupBlockJob *bjob = container_of(job, BackupBlockJob, common);
- if (bjob && bjob->source_bs == di->bs) {
- return job;
- }
- }
- }
- return NULL;
-}
-
static void pvebackup_propagate_error(Error *err)
{
qemu_mutex_lock(&backup_state.stat.lock);
@@ -272,18 +253,6 @@ static void coroutine_fn pvebackup_co_cleanup(void *unused)
if (local_err != NULL) {
pvebackup_propagate_error(local_err);
}
- } else {
- // on error or cancel we cannot ensure synchronization of dirty
- // bitmaps with backup server, so remove all and do full backup next
- GList *l = backup_state.di_list;
- while (l) {
- PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data;
- l = g_list_next(l);
-
- if (di->bitmap) {
- bdrv_release_dirty_bitmap(di->bitmap);
- }
- }
}
proxmox_backup_disconnect(backup_state.pbs);
@@ -322,8 +291,6 @@ static void pvebackup_complete_cb(void *opaque, int ret)
qemu_mutex_lock(&backup_state.backup_mutex);
- di->completed = true;
-
if (ret < 0) {
Error *local_err = NULL;
error_setg(&local_err, "job failed with err %d - %s", ret, strerror(-ret));
@@ -336,20 +303,17 @@ static void pvebackup_complete_cb(void *opaque, int ret)
block_on_coroutine_fn(pvebackup_complete_stream, di);
- // remove self from job queue
+ // remove self from job list
backup_state.di_list = g_list_remove(backup_state.di_list, di);
- if (di->bitmap && ret < 0) {
- // on error or cancel we cannot ensure synchronization of dirty
- // bitmaps with backup server, so remove all and do full backup next
- bdrv_release_dirty_bitmap(di->bitmap);
- }
-
g_free(di);
- qemu_mutex_unlock(&backup_state.backup_mutex);
+ /* call cleanup if we're the last job */
+ if (!g_list_first(backup_state.di_list)) {
+ block_on_coroutine_fn(pvebackup_co_cleanup, NULL);
+ }
- pvebackup_run_next_job();
+ qemu_mutex_unlock(&backup_state.backup_mutex);
}
static void pvebackup_cancel(void)
@@ -371,36 +335,28 @@ static void pvebackup_cancel(void)
proxmox_backup_abort(backup_state.pbs, "backup canceled");
}
+ /* it's enough to cancel one job in the transaction, the rest will follow
+ * automatically */
+ GList *bdi = g_list_first(backup_state.di_list);
+ BlockJob *cancel_job = bdi && bdi->data ?
+ ((PVEBackupDevInfo *)bdi->data)->job :
+ NULL;
+
+ /* ref the job before releasing the mutex, just to be safe */
+ if (cancel_job) {
+ job_ref(&cancel_job->job);
+ }
+
+ /* job_cancel_sync may enter the job, so we need to release the
+ * backup_mutex to avoid deadlock */
qemu_mutex_unlock(&backup_state.backup_mutex);
- for(;;) {
-
- BlockJob *next_job = NULL;
-
- qemu_mutex_lock(&backup_state.backup_mutex);
-
- GList *l = backup_state.di_list;
- while (l) {
- PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data;
- l = g_list_next(l);
-
- BlockJob *job = lookup_active_block_job(di);
- if (job != NULL) {
- next_job = job;
- break;
- }
- }
-
- qemu_mutex_unlock(&backup_state.backup_mutex);
-
- if (next_job) {
- AioContext *aio_context = next_job->job.aio_context;
- aio_context_acquire(aio_context);
- job_cancel_sync(&next_job->job, true);
- aio_context_release(aio_context);
- } else {
- break;
- }
+ if (cancel_job) {
+ AioContext *aio_context = cancel_job->job.aio_context;
+ aio_context_acquire(aio_context);
+ job_cancel_sync(&cancel_job->job, true);
+ job_unref(&cancel_job->job);
+ aio_context_release(aio_context);
}
}
@@ -459,51 +415,19 @@ static int coroutine_fn pvebackup_co_add_config(
goto out;
}
-bool job_should_pause(Job *job);
-
-static void pvebackup_run_next_job(void)
-{
- assert(!qemu_in_coroutine());
-
- qemu_mutex_lock(&backup_state.backup_mutex);
-
- GList *l = backup_state.di_list;
- while (l) {
- PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data;
- l = g_list_next(l);
-
- BlockJob *job = lookup_active_block_job(di);
-
- if (job) {
- qemu_mutex_unlock(&backup_state.backup_mutex);
-
- AioContext *aio_context = job->job.aio_context;
- aio_context_acquire(aio_context);
-
- if (job_should_pause(&job->job)) {
- bool error_or_canceled = pvebackup_error_or_canceled();
- if (error_or_canceled) {
- job_cancel_sync(&job->job, true);
- } else {
- job_resume(&job->job);
- }
- }
- aio_context_release(aio_context);
- return;
- }
- }
-
- block_on_coroutine_fn(pvebackup_co_cleanup, NULL); // no more jobs, run cleanup
-
- qemu_mutex_unlock(&backup_state.backup_mutex);
-}
-
static bool create_backup_jobs(void) {
assert(!qemu_in_coroutine());
Error *local_err = NULL;
+ /* create job transaction to synchronize bitmap commit and cancel all
+ * jobs in case one errors */
+ if (backup_state.txn) {
+ job_txn_unref(backup_state.txn);
+ }
+ backup_state.txn = job_txn_new_seq();
+
BackupPerf perf = { .max_workers = 16 };
/* create and start all jobs (paused state) */
@@ -526,7 +450,7 @@ static bool create_backup_jobs(void) {
BlockJob *job = backup_job_create(
NULL, di->bs, di->target, backup_state.speed, sync_mode, di->bitmap,
bitmap_mode, false, NULL, &perf, BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
- JOB_DEFAULT, pvebackup_complete_cb, di, NULL, &local_err);
+ JOB_DEFAULT, pvebackup_complete_cb, di, backup_state.txn, &local_err);
aio_context_release(aio_context);
@@ -538,7 +462,8 @@ static bool create_backup_jobs(void) {
pvebackup_propagate_error(create_job_err);
break;
}
- job_start(&job->job);
+
+ di->job = job;
bdrv_unref(di->target);
di->target = NULL;
@@ -556,6 +481,10 @@ static bool create_backup_jobs(void) {
bdrv_unref(di->target);
di->target = NULL;
}
+
+ if (di->job) {
+ job_unref(&di->job->job);
+ }
}
}
@@ -946,10 +875,6 @@ err:
PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data;
l = g_list_next(l);
- if (di->bitmap) {
- bdrv_release_dirty_bitmap(di->bitmap);
- }
-
if (di->target) {
bdrv_unref(di->target);
}
@@ -1038,9 +963,15 @@ UuidInfo *qmp_backup(
block_on_coroutine_fn(pvebackup_co_prepare, &task);
if (*errp == NULL) {
- create_backup_jobs();
+ bool errors = create_backup_jobs();
qemu_mutex_unlock(&backup_state.backup_mutex);
- pvebackup_run_next_job();
+
+ if (!errors) {
+ /* start the first job in the transaction
+ * note: this might directly enter the job, so we need to do this
+ * after unlocking the backup_mutex */
+ job_txn_start_seq(backup_state.txn);
+ }
} else {
qemu_mutex_unlock(&backup_state.backup_mutex);
}
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