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d333327a SR |
1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
2 | From: Stefan Reiter <s.reiter@proxmox.com> | |
3 | Date: Thu, 20 Aug 2020 14:25:00 +0200 | |
4 | Subject: [PATCH] PVE-Backup: Use a transaction to synchronize job states | |
5 | ||
6 | By using a JobTxn, we can sync dirty bitmaps only when *all* jobs were | |
7 | successful - meaning we don't need to remove them when the backup fails, | |
8 | since QEMU's BITMAP_SYNC_MODE_ON_SUCCESS will now handle that for us. | |
9 | ||
10 | To keep the rate-limiting and IO impact from before, we use a sequential | |
11 | transaction, so drives will still be backed up one after the other. | |
12 | --- | |
13 | pve-backup.c | 167 +++++++++++++++------------------------------------ | |
14 | 1 file changed, 49 insertions(+), 118 deletions(-) | |
15 | ||
16 | diff --git a/pve-backup.c b/pve-backup.c | |
17 | index 04c21c80aa..9562e9c98d 100644 | |
18 | --- a/pve-backup.c | |
19 | +++ b/pve-backup.c | |
20 | @@ -52,6 +52,7 @@ static struct PVEBackupState { | |
21 | VmaWriter *vmaw; | |
22 | ProxmoxBackupHandle *pbs; | |
23 | GList *di_list; | |
24 | + JobTxn *txn; | |
25 | QemuMutex backup_mutex; | |
26 | CoMutex dump_callback_mutex; | |
27 | } backup_state; | |
28 | @@ -71,32 +72,12 @@ typedef struct PVEBackupDevInfo { | |
29 | size_t size; | |
30 | uint64_t block_size; | |
31 | uint8_t dev_id; | |
32 | - bool completed; | |
33 | char targetfile[PATH_MAX]; | |
34 | BdrvDirtyBitmap *bitmap; | |
35 | BlockDriverState *target; | |
36 | + BlockJob *job; | |
37 | } PVEBackupDevInfo; | |
38 | ||
39 | -static void pvebackup_run_next_job(void); | |
40 | - | |
41 | -static BlockJob * | |
42 | -lookup_active_block_job(PVEBackupDevInfo *di) | |
43 | -{ | |
44 | - if (!di->completed && di->bs) { | |
45 | - for (BlockJob *job = block_job_next(NULL); job; job = block_job_next(job)) { | |
46 | - if (job->job.driver->job_type != JOB_TYPE_BACKUP) { | |
47 | - continue; | |
48 | - } | |
49 | - | |
50 | - BackupBlockJob *bjob = container_of(job, BackupBlockJob, common); | |
51 | - if (bjob && bjob->source_bs == di->bs) { | |
52 | - return job; | |
53 | - } | |
54 | - } | |
55 | - } | |
56 | - return NULL; | |
57 | -} | |
58 | - | |
59 | static void pvebackup_propagate_error(Error *err) | |
60 | { | |
61 | qemu_mutex_lock(&backup_state.stat.lock); | |
62 | @@ -272,18 +253,6 @@ static void coroutine_fn pvebackup_co_cleanup(void *unused) | |
63 | if (local_err != NULL) { | |
64 | pvebackup_propagate_error(local_err); | |
65 | } | |
66 | - } else { | |
67 | - // on error or cancel we cannot ensure synchronization of dirty | |
68 | - // bitmaps with backup server, so remove all and do full backup next | |
69 | - GList *l = backup_state.di_list; | |
70 | - while (l) { | |
71 | - PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data; | |
72 | - l = g_list_next(l); | |
73 | - | |
74 | - if (di->bitmap) { | |
75 | - bdrv_release_dirty_bitmap(di->bitmap); | |
76 | - } | |
77 | - } | |
78 | } | |
79 | ||
80 | proxmox_backup_disconnect(backup_state.pbs); | |
81 | @@ -322,8 +291,6 @@ static void pvebackup_complete_cb(void *opaque, int ret) | |
82 | ||
83 | qemu_mutex_lock(&backup_state.backup_mutex); | |
84 | ||
85 | - di->completed = true; | |
86 | - | |
87 | if (ret < 0) { | |
88 | Error *local_err = NULL; | |
89 | error_setg(&local_err, "job failed with err %d - %s", ret, strerror(-ret)); | |
90 | @@ -336,20 +303,17 @@ static void pvebackup_complete_cb(void *opaque, int ret) | |
91 | ||
92 | block_on_coroutine_fn(pvebackup_complete_stream, di); | |
93 | ||
94 | - // remove self from job queue | |
95 | + // remove self from job list | |
96 | backup_state.di_list = g_list_remove(backup_state.di_list, di); | |
97 | ||
98 | - if (di->bitmap && ret < 0) { | |
99 | - // on error or cancel we cannot ensure synchronization of dirty | |
100 | - // bitmaps with backup server, so remove all and do full backup next | |
101 | - bdrv_release_dirty_bitmap(di->bitmap); | |
102 | - } | |
103 | - | |
104 | g_free(di); | |
105 | ||
106 | - qemu_mutex_unlock(&backup_state.backup_mutex); | |
107 | + /* call cleanup if we're the last job */ | |
108 | + if (!g_list_first(backup_state.di_list)) { | |
109 | + block_on_coroutine_fn(pvebackup_co_cleanup, NULL); | |
110 | + } | |
111 | ||
112 | - pvebackup_run_next_job(); | |
113 | + qemu_mutex_unlock(&backup_state.backup_mutex); | |
114 | } | |
115 | ||
116 | static void pvebackup_cancel(void) | |
117 | @@ -371,36 +335,28 @@ static void pvebackup_cancel(void) | |
118 | proxmox_backup_abort(backup_state.pbs, "backup canceled"); | |
119 | } | |
120 | ||
121 | - qemu_mutex_unlock(&backup_state.backup_mutex); | |
122 | - | |
123 | - for(;;) { | |
124 | - | |
125 | - BlockJob *next_job = NULL; | |
126 | - | |
127 | - qemu_mutex_lock(&backup_state.backup_mutex); | |
128 | - | |
129 | - GList *l = backup_state.di_list; | |
130 | - while (l) { | |
131 | - PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data; | |
132 | - l = g_list_next(l); | |
133 | + /* it's enough to cancel one job in the transaction, the rest will follow | |
134 | + * automatically */ | |
135 | + GList *bdi = g_list_first(backup_state.di_list); | |
136 | + BlockJob *cancel_job = bdi && bdi->data ? | |
137 | + ((PVEBackupDevInfo *)bdi->data)->job : | |
138 | + NULL; | |
139 | ||
140 | - BlockJob *job = lookup_active_block_job(di); | |
141 | - if (job != NULL) { | |
142 | - next_job = job; | |
143 | - break; | |
144 | - } | |
145 | - } | |
146 | + /* ref the job before releasing the mutex, just to be safe */ | |
147 | + if (cancel_job) { | |
148 | + job_ref(&cancel_job->job); | |
149 | + } | |
150 | ||
151 | - qemu_mutex_unlock(&backup_state.backup_mutex); | |
152 | + /* job_cancel_sync may enter the job, so we need to release the | |
153 | + * backup_mutex to avoid deadlock */ | |
154 | + qemu_mutex_unlock(&backup_state.backup_mutex); | |
155 | ||
156 | - if (next_job) { | |
157 | - AioContext *aio_context = next_job->job.aio_context; | |
158 | - aio_context_acquire(aio_context); | |
159 | - job_cancel_sync(&next_job->job); | |
160 | - aio_context_release(aio_context); | |
161 | - } else { | |
162 | - break; | |
163 | - } | |
164 | + if (cancel_job) { | |
165 | + AioContext *aio_context = cancel_job->job.aio_context; | |
166 | + aio_context_acquire(aio_context); | |
167 | + job_cancel_sync(&cancel_job->job); | |
168 | + job_unref(&cancel_job->job); | |
169 | + aio_context_release(aio_context); | |
170 | } | |
171 | } | |
172 | ||
173 | @@ -459,51 +415,19 @@ static int coroutine_fn pvebackup_co_add_config( | |
174 | goto out; | |
175 | } | |
176 | ||
177 | -bool job_should_pause(Job *job); | |
178 | - | |
179 | -static void pvebackup_run_next_job(void) | |
180 | -{ | |
181 | - assert(!qemu_in_coroutine()); | |
182 | - | |
183 | - qemu_mutex_lock(&backup_state.backup_mutex); | |
184 | - | |
185 | - GList *l = backup_state.di_list; | |
186 | - while (l) { | |
187 | - PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data; | |
188 | - l = g_list_next(l); | |
189 | - | |
190 | - BlockJob *job = lookup_active_block_job(di); | |
191 | - | |
192 | - if (job) { | |
193 | - qemu_mutex_unlock(&backup_state.backup_mutex); | |
194 | - | |
195 | - AioContext *aio_context = job->job.aio_context; | |
196 | - aio_context_acquire(aio_context); | |
197 | - | |
198 | - if (job_should_pause(&job->job)) { | |
199 | - bool error_or_canceled = pvebackup_error_or_canceled(); | |
200 | - if (error_or_canceled) { | |
201 | - job_cancel_sync(&job->job); | |
202 | - } else { | |
203 | - job_resume(&job->job); | |
204 | - } | |
205 | - } | |
206 | - aio_context_release(aio_context); | |
207 | - return; | |
208 | - } | |
209 | - } | |
210 | - | |
211 | - block_on_coroutine_fn(pvebackup_co_cleanup, NULL); // no more jobs, run cleanup | |
212 | - | |
213 | - qemu_mutex_unlock(&backup_state.backup_mutex); | |
214 | -} | |
215 | - | |
216 | static bool create_backup_jobs(void) { | |
217 | ||
218 | assert(!qemu_in_coroutine()); | |
219 | ||
220 | Error *local_err = NULL; | |
221 | ||
222 | + /* create job transaction to synchronize bitmap commit and cancel all | |
223 | + * jobs in case one errors */ | |
224 | + if (backup_state.txn) { | |
225 | + job_txn_unref(backup_state.txn); | |
226 | + } | |
227 | + backup_state.txn = job_txn_new_seq(); | |
228 | + | |
229 | /* create and start all jobs (paused state) */ | |
230 | GList *l = backup_state.di_list; | |
231 | while (l) { | |
232 | @@ -524,7 +448,7 @@ static bool create_backup_jobs(void) { | |
233 | BlockJob *job = backup_job_create( | |
234 | NULL, di->bs, di->target, backup_state.speed, sync_mode, di->bitmap, | |
235 | bitmap_mode, false, NULL, BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT, | |
236 | - JOB_DEFAULT, pvebackup_complete_cb, di, 1, NULL, &local_err); | |
237 | + JOB_DEFAULT, pvebackup_complete_cb, di, backup_state.txn, &local_err); | |
238 | ||
239 | aio_context_release(aio_context); | |
240 | ||
241 | @@ -536,7 +460,8 @@ static bool create_backup_jobs(void) { | |
242 | pvebackup_propagate_error(create_job_err); | |
243 | break; | |
244 | } | |
245 | - job_start(&job->job); | |
246 | + | |
247 | + di->job = job; | |
248 | ||
249 | bdrv_unref(di->target); | |
250 | di->target = NULL; | |
251 | @@ -554,6 +479,10 @@ static bool create_backup_jobs(void) { | |
252 | bdrv_unref(di->target); | |
253 | di->target = NULL; | |
254 | } | |
255 | + | |
256 | + if (di->job) { | |
257 | + job_unref(&di->job->job); | |
258 | + } | |
259 | } | |
260 | } | |
261 | ||
262 | @@ -944,10 +873,6 @@ err: | |
263 | PVEBackupDevInfo *di = (PVEBackupDevInfo *)l->data; | |
264 | l = g_list_next(l); | |
265 | ||
266 | - if (di->bitmap) { | |
267 | - bdrv_release_dirty_bitmap(di->bitmap); | |
268 | - } | |
269 | - | |
270 | if (di->target) { | |
271 | bdrv_unref(di->target); | |
272 | } | |
273 | @@ -1036,9 +961,15 @@ UuidInfo *qmp_backup( | |
274 | block_on_coroutine_fn(pvebackup_co_prepare, &task); | |
275 | ||
276 | if (*errp == NULL) { | |
277 | - create_backup_jobs(); | |
278 | + bool errors = create_backup_jobs(); | |
279 | qemu_mutex_unlock(&backup_state.backup_mutex); | |
280 | - pvebackup_run_next_job(); | |
281 | + | |
282 | + if (!errors) { | |
283 | + /* start the first job in the transaction | |
284 | + * note: this might directly enter the job, so we need to do this | |
285 | + * after unlocking the backup_mutex */ | |
286 | + job_txn_start_seq(backup_state.txn); | |
287 | + } | |
288 | } else { | |
289 | qemu_mutex_unlock(&backup_state.backup_mutex); | |
290 | } |