linux-user: Use safe_syscall for open and openat system calls
[qemu.git] / block / commit.c
1 /*
2 * Live block commit
3 *
4 * Copyright Red Hat, Inc. 2012
5 *
6 * Authors:
7 * Jeff Cody <jcody@redhat.com>
8 * Based on stream.c by Stefan Hajnoczi
9 *
10 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
11 * See the COPYING.LIB file in the top-level directory.
12 *
13 */
14
15 #include "qemu/osdep.h"
16 #include "trace.h"
17 #include "block/block_int.h"
18 #include "block/blockjob.h"
19 #include "qapi/error.h"
20 #include "qapi/qmp/qerror.h"
21 #include "qemu/ratelimit.h"
22 #include "sysemu/block-backend.h"
23
24 enum {
25 /*
26 * Size of data buffer for populating the image file. This should be large
27 * enough to process multiple clusters in a single call, so that populating
28 * contiguous regions of the image is efficient.
29 */
30 COMMIT_BUFFER_SIZE = 512 * 1024, /* in bytes */
31 };
32
33 #define SLICE_TIME 100000000ULL /* ns */
34
35 typedef struct CommitBlockJob {
36 BlockJob common;
37 RateLimit limit;
38 BlockDriverState *active;
39 BlockDriverState *top;
40 BlockDriverState *base;
41 BlockdevOnError on_error;
42 int base_flags;
43 int orig_overlay_flags;
44 char *backing_file_str;
45 } CommitBlockJob;
46
47 static int coroutine_fn commit_populate(BlockDriverState *bs,
48 BlockDriverState *base,
49 int64_t sector_num, int nb_sectors,
50 void *buf)
51 {
52 int ret = 0;
53
54 ret = bdrv_read(bs, sector_num, buf, nb_sectors);
55 if (ret) {
56 return ret;
57 }
58
59 ret = bdrv_write(base, sector_num, buf, nb_sectors);
60 if (ret) {
61 return ret;
62 }
63
64 return 0;
65 }
66
67 typedef struct {
68 int ret;
69 } CommitCompleteData;
70
71 static void commit_complete(BlockJob *job, void *opaque)
72 {
73 CommitBlockJob *s = container_of(job, CommitBlockJob, common);
74 CommitCompleteData *data = opaque;
75 BlockDriverState *active = s->active;
76 BlockDriverState *top = s->top;
77 BlockDriverState *base = s->base;
78 BlockDriverState *overlay_bs;
79 int ret = data->ret;
80
81 if (!block_job_is_cancelled(&s->common) && ret == 0) {
82 /* success */
83 ret = bdrv_drop_intermediate(active, top, base, s->backing_file_str);
84 }
85
86 /* restore base open flags here if appropriate (e.g., change the base back
87 * to r/o). These reopens do not need to be atomic, since we won't abort
88 * even on failure here */
89 if (s->base_flags != bdrv_get_flags(base)) {
90 bdrv_reopen(base, s->base_flags, NULL);
91 }
92 overlay_bs = bdrv_find_overlay(active, top);
93 if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
94 bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
95 }
96 g_free(s->backing_file_str);
97 block_job_completed(&s->common, ret);
98 g_free(data);
99 }
100
101 static void coroutine_fn commit_run(void *opaque)
102 {
103 CommitBlockJob *s = opaque;
104 CommitCompleteData *data;
105 BlockDriverState *top = s->top;
106 BlockDriverState *base = s->base;
107 int64_t sector_num, end;
108 int ret = 0;
109 int n = 0;
110 void *buf = NULL;
111 int bytes_written = 0;
112 int64_t base_len;
113
114 ret = s->common.len = bdrv_getlength(top);
115
116
117 if (s->common.len < 0) {
118 goto out;
119 }
120
121 ret = base_len = bdrv_getlength(base);
122 if (base_len < 0) {
123 goto out;
124 }
125
126 if (base_len < s->common.len) {
127 ret = bdrv_truncate(base, s->common.len);
128 if (ret) {
129 goto out;
130 }
131 }
132
133 end = s->common.len >> BDRV_SECTOR_BITS;
134 buf = qemu_blockalign(top, COMMIT_BUFFER_SIZE);
135
136 for (sector_num = 0; sector_num < end; sector_num += n) {
137 uint64_t delay_ns = 0;
138 bool copy;
139
140 wait:
141 /* Note that even when no rate limit is applied we need to yield
142 * with no pending I/O here so that bdrv_drain_all() returns.
143 */
144 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
145 if (block_job_is_cancelled(&s->common)) {
146 break;
147 }
148 /* Copy if allocated above the base */
149 ret = bdrv_is_allocated_above(top, base, sector_num,
150 COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE,
151 &n);
152 copy = (ret == 1);
153 trace_commit_one_iteration(s, sector_num, n, ret);
154 if (copy) {
155 if (s->common.speed) {
156 delay_ns = ratelimit_calculate_delay(&s->limit, n);
157 if (delay_ns > 0) {
158 goto wait;
159 }
160 }
161 ret = commit_populate(top, base, sector_num, n, buf);
162 bytes_written += n * BDRV_SECTOR_SIZE;
163 }
164 if (ret < 0) {
165 if (s->on_error == BLOCKDEV_ON_ERROR_STOP ||
166 s->on_error == BLOCKDEV_ON_ERROR_REPORT||
167 (s->on_error == BLOCKDEV_ON_ERROR_ENOSPC && ret == -ENOSPC)) {
168 goto out;
169 } else {
170 n = 0;
171 continue;
172 }
173 }
174 /* Publish progress */
175 s->common.offset += n * BDRV_SECTOR_SIZE;
176 }
177
178 ret = 0;
179
180 out:
181 qemu_vfree(buf);
182
183 data = g_malloc(sizeof(*data));
184 data->ret = ret;
185 block_job_defer_to_main_loop(&s->common, commit_complete, data);
186 }
187
188 static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp)
189 {
190 CommitBlockJob *s = container_of(job, CommitBlockJob, common);
191
192 if (speed < 0) {
193 error_setg(errp, QERR_INVALID_PARAMETER, "speed");
194 return;
195 }
196 ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
197 }
198
199 static const BlockJobDriver commit_job_driver = {
200 .instance_size = sizeof(CommitBlockJob),
201 .job_type = BLOCK_JOB_TYPE_COMMIT,
202 .set_speed = commit_set_speed,
203 };
204
205 void commit_start(BlockDriverState *bs, BlockDriverState *base,
206 BlockDriverState *top, int64_t speed,
207 BlockdevOnError on_error, BlockCompletionFunc *cb,
208 void *opaque, const char *backing_file_str, Error **errp)
209 {
210 CommitBlockJob *s;
211 BlockReopenQueue *reopen_queue = NULL;
212 int orig_overlay_flags;
213 int orig_base_flags;
214 BlockDriverState *overlay_bs;
215 Error *local_err = NULL;
216
217 assert(top != bs);
218 if (top == base) {
219 error_setg(errp, "Invalid files for merge: top and base are the same");
220 return;
221 }
222
223 overlay_bs = bdrv_find_overlay(bs, top);
224
225 if (overlay_bs == NULL) {
226 error_setg(errp, "Could not find overlay image for %s:", top->filename);
227 return;
228 }
229
230 orig_base_flags = bdrv_get_flags(base);
231 orig_overlay_flags = bdrv_get_flags(overlay_bs);
232
233 /* convert base & overlay_bs to r/w, if necessary */
234 if (!(orig_overlay_flags & BDRV_O_RDWR)) {
235 reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs, NULL,
236 orig_overlay_flags | BDRV_O_RDWR);
237 }
238 if (!(orig_base_flags & BDRV_O_RDWR)) {
239 reopen_queue = bdrv_reopen_queue(reopen_queue, base, NULL,
240 orig_base_flags | BDRV_O_RDWR);
241 }
242 if (reopen_queue) {
243 bdrv_reopen_multiple(reopen_queue, &local_err);
244 if (local_err != NULL) {
245 error_propagate(errp, local_err);
246 return;
247 }
248 }
249
250
251 s = block_job_create(&commit_job_driver, bs, speed, cb, opaque, errp);
252 if (!s) {
253 return;
254 }
255
256 s->base = base;
257 s->top = top;
258 s->active = bs;
259
260 s->base_flags = orig_base_flags;
261 s->orig_overlay_flags = orig_overlay_flags;
262
263 s->backing_file_str = g_strdup(backing_file_str);
264
265 s->on_error = on_error;
266 s->common.co = qemu_coroutine_create(commit_run);
267
268 trace_commit_start(bs, base, top, s, s->common.co, opaque);
269 qemu_coroutine_enter(s->common.co, s);
270 }