Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging
[qemu.git] / block / backup.c
1 /*
2 * QEMU backup
3 *
4 * Copyright (C) 2013 Proxmox Server Solutions
5 *
6 * Authors:
7 * Dietmar Maurer (dietmar@proxmox.com)
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 *
12 */
13
14 #include <stdio.h>
15 #include <errno.h>
16 #include <unistd.h>
17
18 #include "trace.h"
19 #include "block/block.h"
20 #include "block/block_int.h"
21 #include "block/blockjob.h"
22 #include "qemu/ratelimit.h"
23
24 #define BACKUP_CLUSTER_BITS 16
25 #define BACKUP_CLUSTER_SIZE (1 << BACKUP_CLUSTER_BITS)
26 #define BACKUP_SECTORS_PER_CLUSTER (BACKUP_CLUSTER_SIZE / BDRV_SECTOR_SIZE)
27
28 #define SLICE_TIME 100000000ULL /* ns */
29
30 typedef struct CowRequest {
31 int64_t start;
32 int64_t end;
33 QLIST_ENTRY(CowRequest) list;
34 CoQueue wait_queue; /* coroutines blocked on this request */
35 } CowRequest;
36
37 typedef struct BackupBlockJob {
38 BlockJob common;
39 BlockDriverState *target;
40 MirrorSyncMode sync_mode;
41 RateLimit limit;
42 BlockdevOnError on_source_error;
43 BlockdevOnError on_target_error;
44 CoRwlock flush_rwlock;
45 uint64_t sectors_read;
46 HBitmap *bitmap;
47 QLIST_HEAD(, CowRequest) inflight_reqs;
48 } BackupBlockJob;
49
50 /* See if in-flight requests overlap and wait for them to complete */
51 static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
52 int64_t start,
53 int64_t end)
54 {
55 CowRequest *req;
56 bool retry;
57
58 do {
59 retry = false;
60 QLIST_FOREACH(req, &job->inflight_reqs, list) {
61 if (end > req->start && start < req->end) {
62 qemu_co_queue_wait(&req->wait_queue);
63 retry = true;
64 break;
65 }
66 }
67 } while (retry);
68 }
69
70 /* Keep track of an in-flight request */
71 static void cow_request_begin(CowRequest *req, BackupBlockJob *job,
72 int64_t start, int64_t end)
73 {
74 req->start = start;
75 req->end = end;
76 qemu_co_queue_init(&req->wait_queue);
77 QLIST_INSERT_HEAD(&job->inflight_reqs, req, list);
78 }
79
80 /* Forget about a completed request */
81 static void cow_request_end(CowRequest *req)
82 {
83 QLIST_REMOVE(req, list);
84 qemu_co_queue_restart_all(&req->wait_queue);
85 }
86
87 static int coroutine_fn backup_do_cow(BlockDriverState *bs,
88 int64_t sector_num, int nb_sectors,
89 bool *error_is_read)
90 {
91 BackupBlockJob *job = (BackupBlockJob *)bs->job;
92 CowRequest cow_request;
93 struct iovec iov;
94 QEMUIOVector bounce_qiov;
95 void *bounce_buffer = NULL;
96 int ret = 0;
97 int64_t start, end;
98 int n;
99
100 qemu_co_rwlock_rdlock(&job->flush_rwlock);
101
102 start = sector_num / BACKUP_SECTORS_PER_CLUSTER;
103 end = DIV_ROUND_UP(sector_num + nb_sectors, BACKUP_SECTORS_PER_CLUSTER);
104
105 trace_backup_do_cow_enter(job, start, sector_num, nb_sectors);
106
107 wait_for_overlapping_requests(job, start, end);
108 cow_request_begin(&cow_request, job, start, end);
109
110 for (; start < end; start++) {
111 if (hbitmap_get(job->bitmap, start)) {
112 trace_backup_do_cow_skip(job, start);
113 continue; /* already copied */
114 }
115
116 trace_backup_do_cow_process(job, start);
117
118 n = MIN(BACKUP_SECTORS_PER_CLUSTER,
119 job->common.len / BDRV_SECTOR_SIZE -
120 start * BACKUP_SECTORS_PER_CLUSTER);
121
122 if (!bounce_buffer) {
123 bounce_buffer = qemu_blockalign(bs, BACKUP_CLUSTER_SIZE);
124 }
125 iov.iov_base = bounce_buffer;
126 iov.iov_len = n * BDRV_SECTOR_SIZE;
127 qemu_iovec_init_external(&bounce_qiov, &iov, 1);
128
129 ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n,
130 &bounce_qiov);
131 if (ret < 0) {
132 trace_backup_do_cow_read_fail(job, start, ret);
133 if (error_is_read) {
134 *error_is_read = true;
135 }
136 goto out;
137 }
138
139 if (buffer_is_zero(iov.iov_base, iov.iov_len)) {
140 ret = bdrv_co_write_zeroes(job->target,
141 start * BACKUP_SECTORS_PER_CLUSTER,
142 n, BDRV_REQ_MAY_UNMAP);
143 } else {
144 ret = bdrv_co_writev(job->target,
145 start * BACKUP_SECTORS_PER_CLUSTER, n,
146 &bounce_qiov);
147 }
148 if (ret < 0) {
149 trace_backup_do_cow_write_fail(job, start, ret);
150 if (error_is_read) {
151 *error_is_read = false;
152 }
153 goto out;
154 }
155
156 hbitmap_set(job->bitmap, start, 1);
157
158 /* Publish progress, guest I/O counts as progress too. Note that the
159 * offset field is an opaque progress value, it is not a disk offset.
160 */
161 job->sectors_read += n;
162 job->common.offset += n * BDRV_SECTOR_SIZE;
163 }
164
165 out:
166 if (bounce_buffer) {
167 qemu_vfree(bounce_buffer);
168 }
169
170 cow_request_end(&cow_request);
171
172 trace_backup_do_cow_return(job, sector_num, nb_sectors, ret);
173
174 qemu_co_rwlock_unlock(&job->flush_rwlock);
175
176 return ret;
177 }
178
179 static int coroutine_fn backup_before_write_notify(
180 NotifierWithReturn *notifier,
181 void *opaque)
182 {
183 BdrvTrackedRequest *req = opaque;
184 int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
185 int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
186
187 assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
188 assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
189
190 return backup_do_cow(req->bs, sector_num, nb_sectors, NULL);
191 }
192
193 static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
194 {
195 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
196
197 if (speed < 0) {
198 error_set(errp, QERR_INVALID_PARAMETER, "speed");
199 return;
200 }
201 ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
202 }
203
204 static void backup_iostatus_reset(BlockJob *job)
205 {
206 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
207
208 bdrv_iostatus_reset(s->target);
209 }
210
211 static const BlockJobDriver backup_job_driver = {
212 .instance_size = sizeof(BackupBlockJob),
213 .job_type = BLOCK_JOB_TYPE_BACKUP,
214 .set_speed = backup_set_speed,
215 .iostatus_reset = backup_iostatus_reset,
216 };
217
218 static BlockErrorAction backup_error_action(BackupBlockJob *job,
219 bool read, int error)
220 {
221 if (read) {
222 return block_job_error_action(&job->common, job->common.bs,
223 job->on_source_error, true, error);
224 } else {
225 return block_job_error_action(&job->common, job->target,
226 job->on_target_error, false, error);
227 }
228 }
229
230 static void coroutine_fn backup_run(void *opaque)
231 {
232 BackupBlockJob *job = opaque;
233 BlockDriverState *bs = job->common.bs;
234 BlockDriverState *target = job->target;
235 BlockdevOnError on_target_error = job->on_target_error;
236 NotifierWithReturn before_write = {
237 .notify = backup_before_write_notify,
238 };
239 int64_t start, end;
240 int ret = 0;
241
242 QLIST_INIT(&job->inflight_reqs);
243 qemu_co_rwlock_init(&job->flush_rwlock);
244
245 start = 0;
246 end = DIV_ROUND_UP(job->common.len / BDRV_SECTOR_SIZE,
247 BACKUP_SECTORS_PER_CLUSTER);
248
249 job->bitmap = hbitmap_alloc(end, 0);
250
251 bdrv_set_enable_write_cache(target, true);
252 bdrv_set_on_error(target, on_target_error, on_target_error);
253 bdrv_iostatus_enable(target);
254
255 bdrv_add_before_write_notifier(bs, &before_write);
256
257 if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
258 while (!block_job_is_cancelled(&job->common)) {
259 /* Yield until the job is cancelled. We just let our before_write
260 * notify callback service CoW requests. */
261 job->common.busy = false;
262 qemu_coroutine_yield();
263 job->common.busy = true;
264 }
265 } else {
266 /* Both FULL and TOP SYNC_MODE's require copying.. */
267 for (; start < end; start++) {
268 bool error_is_read;
269
270 if (block_job_is_cancelled(&job->common)) {
271 break;
272 }
273
274 /* we need to yield so that qemu_aio_flush() returns.
275 * (without, VM does not reboot)
276 */
277 if (job->common.speed) {
278 uint64_t delay_ns = ratelimit_calculate_delay(
279 &job->limit, job->sectors_read);
280 job->sectors_read = 0;
281 block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns);
282 } else {
283 block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0);
284 }
285
286 if (block_job_is_cancelled(&job->common)) {
287 break;
288 }
289
290 if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
291 int i, n;
292 int alloced = 0;
293
294 /* Check to see if these blocks are already in the
295 * backing file. */
296
297 for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) {
298 /* bdrv_is_allocated() only returns true/false based
299 * on the first set of sectors it comes across that
300 * are are all in the same state.
301 * For that reason we must verify each sector in the
302 * backup cluster length. We end up copying more than
303 * needed but at some point that is always the case. */
304 alloced =
305 bdrv_is_allocated(bs,
306 start * BACKUP_SECTORS_PER_CLUSTER + i,
307 BACKUP_SECTORS_PER_CLUSTER - i, &n);
308 i += n;
309
310 if (alloced == 1) {
311 break;
312 }
313 }
314
315 /* If the above loop never found any sectors that are in
316 * the topmost image, skip this backup. */
317 if (alloced == 0) {
318 continue;
319 }
320 }
321 /* FULL sync mode we copy the whole drive. */
322 ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
323 BACKUP_SECTORS_PER_CLUSTER, &error_is_read);
324 if (ret < 0) {
325 /* Depending on error action, fail now or retry cluster */
326 BlockErrorAction action =
327 backup_error_action(job, error_is_read, -ret);
328 if (action == BDRV_ACTION_REPORT) {
329 break;
330 } else {
331 start--;
332 continue;
333 }
334 }
335 }
336 }
337
338 notifier_with_return_remove(&before_write);
339
340 /* wait until pending backup_do_cow() calls have completed */
341 qemu_co_rwlock_wrlock(&job->flush_rwlock);
342 qemu_co_rwlock_unlock(&job->flush_rwlock);
343
344 hbitmap_free(job->bitmap);
345
346 bdrv_iostatus_disable(target);
347 bdrv_unref(target);
348
349 block_job_completed(&job->common, ret);
350 }
351
352 void backup_start(BlockDriverState *bs, BlockDriverState *target,
353 int64_t speed, MirrorSyncMode sync_mode,
354 BlockdevOnError on_source_error,
355 BlockdevOnError on_target_error,
356 BlockDriverCompletionFunc *cb, void *opaque,
357 Error **errp)
358 {
359 int64_t len;
360
361 assert(bs);
362 assert(target);
363 assert(cb);
364
365 if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
366 on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
367 !bdrv_iostatus_is_enabled(bs)) {
368 error_set(errp, QERR_INVALID_PARAMETER, "on-source-error");
369 return;
370 }
371
372 len = bdrv_getlength(bs);
373 if (len < 0) {
374 error_setg_errno(errp, -len, "unable to get length for '%s'",
375 bdrv_get_device_name(bs));
376 return;
377 }
378
379 BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed,
380 cb, opaque, errp);
381 if (!job) {
382 return;
383 }
384
385 job->on_source_error = on_source_error;
386 job->on_target_error = on_target_error;
387 job->target = target;
388 job->sync_mode = sync_mode;
389 job->common.len = len;
390 job->common.co = qemu_coroutine_create(backup_run);
391 qemu_coroutine_enter(job->common.co, job);
392 }