Merge remote-tracking branch 'remotes/kraxel/tags/pull-usb-20141112-1' into staging
[qemu-kvm.git] / block / backup.c
blob792e65514bfdaa75e95500cc711aee60c437ffd9
1 /*
2 * QEMU backup
4 * Copyright (C) 2013 Proxmox Server Solutions
6 * Authors:
7 * Dietmar Maurer (dietmar@proxmox.com)
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.
14 #include <stdio.h>
15 #include <errno.h>
16 #include <unistd.h>
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"
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)
28 #define SLICE_TIME 100000000ULL /* ns */
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;
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;
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)
55 CowRequest *req;
56 bool retry;
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;
67 } while (retry);
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)
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);
80 /* Forget about a completed request */
81 static void cow_request_end(CowRequest *req)
83 QLIST_REMOVE(req, list);
84 qemu_co_queue_restart_all(&req->wait_queue);
87 static int coroutine_fn backup_do_cow(BlockDriverState *bs,
88 int64_t sector_num, int nb_sectors,
89 bool *error_is_read)
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;
100 qemu_co_rwlock_rdlock(&job->flush_rwlock);
102 start = sector_num / BACKUP_SECTORS_PER_CLUSTER;
103 end = DIV_ROUND_UP(sector_num + nb_sectors, BACKUP_SECTORS_PER_CLUSTER);
105 trace_backup_do_cow_enter(job, start, sector_num, nb_sectors);
107 wait_for_overlapping_requests(job, start, end);
108 cow_request_begin(&cow_request, job, start, end);
110 for (; start < end; start++) {
111 if (hbitmap_get(job->bitmap, start)) {
112 trace_backup_do_cow_skip(job, start);
113 continue; /* already copied */
116 trace_backup_do_cow_process(job, start);
118 n = MIN(BACKUP_SECTORS_PER_CLUSTER,
119 job->common.len / BDRV_SECTOR_SIZE -
120 start * BACKUP_SECTORS_PER_CLUSTER);
122 if (!bounce_buffer) {
123 bounce_buffer = qemu_blockalign(bs, BACKUP_CLUSTER_SIZE);
125 iov.iov_base = bounce_buffer;
126 iov.iov_len = n * BDRV_SECTOR_SIZE;
127 qemu_iovec_init_external(&bounce_qiov, &iov, 1);
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;
136 goto out;
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);
148 if (ret < 0) {
149 trace_backup_do_cow_write_fail(job, start, ret);
150 if (error_is_read) {
151 *error_is_read = false;
153 goto out;
156 hbitmap_set(job->bitmap, start, 1);
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.
161 job->sectors_read += n;
162 job->common.offset += n * BDRV_SECTOR_SIZE;
165 out:
166 if (bounce_buffer) {
167 qemu_vfree(bounce_buffer);
170 cow_request_end(&cow_request);
172 trace_backup_do_cow_return(job, sector_num, nb_sectors, ret);
174 qemu_co_rwlock_unlock(&job->flush_rwlock);
176 return ret;
179 static int coroutine_fn backup_before_write_notify(
180 NotifierWithReturn *notifier,
181 void *opaque)
183 BdrvTrackedRequest *req = opaque;
184 int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
185 int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
187 assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
188 assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
190 return backup_do_cow(req->bs, sector_num, nb_sectors, NULL);
193 static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
195 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
197 if (speed < 0) {
198 error_set(errp, QERR_INVALID_PARAMETER, "speed");
199 return;
201 ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
204 static void backup_iostatus_reset(BlockJob *job)
206 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
208 bdrv_iostatus_reset(s->target);
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,
218 static BlockErrorAction backup_error_action(BackupBlockJob *job,
219 bool read, int error)
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);
230 typedef struct {
231 int ret;
232 } BackupCompleteData;
234 static void backup_complete(BlockJob *job, void *opaque)
236 BackupBlockJob *s = container_of(job, BackupBlockJob, common);
237 BackupCompleteData *data = opaque;
239 bdrv_unref(s->target);
241 block_job_completed(job, data->ret);
242 g_free(data);
245 static void coroutine_fn backup_run(void *opaque)
247 BackupBlockJob *job = opaque;
248 BackupCompleteData *data;
249 BlockDriverState *bs = job->common.bs;
250 BlockDriverState *target = job->target;
251 BlockdevOnError on_target_error = job->on_target_error;
252 NotifierWithReturn before_write = {
253 .notify = backup_before_write_notify,
255 int64_t start, end;
256 int ret = 0;
258 QLIST_INIT(&job->inflight_reqs);
259 qemu_co_rwlock_init(&job->flush_rwlock);
261 start = 0;
262 end = DIV_ROUND_UP(job->common.len / BDRV_SECTOR_SIZE,
263 BACKUP_SECTORS_PER_CLUSTER);
265 job->bitmap = hbitmap_alloc(end, 0);
267 bdrv_set_enable_write_cache(target, true);
268 bdrv_set_on_error(target, on_target_error, on_target_error);
269 bdrv_iostatus_enable(target);
271 bdrv_add_before_write_notifier(bs, &before_write);
273 if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
274 while (!block_job_is_cancelled(&job->common)) {
275 /* Yield until the job is cancelled. We just let our before_write
276 * notify callback service CoW requests. */
277 job->common.busy = false;
278 qemu_coroutine_yield();
279 job->common.busy = true;
281 } else {
282 /* Both FULL and TOP SYNC_MODE's require copying.. */
283 for (; start < end; start++) {
284 bool error_is_read;
286 if (block_job_is_cancelled(&job->common)) {
287 break;
290 /* we need to yield so that qemu_aio_flush() returns.
291 * (without, VM does not reboot)
293 if (job->common.speed) {
294 uint64_t delay_ns = ratelimit_calculate_delay(
295 &job->limit, job->sectors_read);
296 job->sectors_read = 0;
297 block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns);
298 } else {
299 block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0);
302 if (block_job_is_cancelled(&job->common)) {
303 break;
306 if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
307 int i, n;
308 int alloced = 0;
310 /* Check to see if these blocks are already in the
311 * backing file. */
313 for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) {
314 /* bdrv_is_allocated() only returns true/false based
315 * on the first set of sectors it comes across that
316 * are are all in the same state.
317 * For that reason we must verify each sector in the
318 * backup cluster length. We end up copying more than
319 * needed but at some point that is always the case. */
320 alloced =
321 bdrv_is_allocated(bs,
322 start * BACKUP_SECTORS_PER_CLUSTER + i,
323 BACKUP_SECTORS_PER_CLUSTER - i, &n);
324 i += n;
326 if (alloced == 1 || n == 0) {
327 break;
331 /* If the above loop never found any sectors that are in
332 * the topmost image, skip this backup. */
333 if (alloced == 0) {
334 continue;
337 /* FULL sync mode we copy the whole drive. */
338 ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
339 BACKUP_SECTORS_PER_CLUSTER, &error_is_read);
340 if (ret < 0) {
341 /* Depending on error action, fail now or retry cluster */
342 BlockErrorAction action =
343 backup_error_action(job, error_is_read, -ret);
344 if (action == BLOCK_ERROR_ACTION_REPORT) {
345 break;
346 } else {
347 start--;
348 continue;
354 notifier_with_return_remove(&before_write);
356 /* wait until pending backup_do_cow() calls have completed */
357 qemu_co_rwlock_wrlock(&job->flush_rwlock);
358 qemu_co_rwlock_unlock(&job->flush_rwlock);
360 hbitmap_free(job->bitmap);
362 bdrv_iostatus_disable(target);
364 data = g_malloc(sizeof(*data));
365 data->ret = ret;
366 block_job_defer_to_main_loop(&job->common, backup_complete, data);
369 void backup_start(BlockDriverState *bs, BlockDriverState *target,
370 int64_t speed, MirrorSyncMode sync_mode,
371 BlockdevOnError on_source_error,
372 BlockdevOnError on_target_error,
373 BlockCompletionFunc *cb, void *opaque,
374 Error **errp)
376 int64_t len;
378 assert(bs);
379 assert(target);
380 assert(cb);
382 if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
383 on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
384 !bdrv_iostatus_is_enabled(bs)) {
385 error_set(errp, QERR_INVALID_PARAMETER, "on-source-error");
386 return;
389 len = bdrv_getlength(bs);
390 if (len < 0) {
391 error_setg_errno(errp, -len, "unable to get length for '%s'",
392 bdrv_get_device_name(bs));
393 return;
396 BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed,
397 cb, opaque, errp);
398 if (!job) {
399 return;
402 job->on_source_error = on_source_error;
403 job->on_target_error = on_target_error;
404 job->target = target;
405 job->sync_mode = sync_mode;
406 job->common.len = len;
407 job->common.co = qemu_coroutine_create(backup_run);
408 qemu_coroutine_enter(job->common.co, job);