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7df7868b VSO |
1 | /* |
2 | * backup-top filter driver | |
3 | * | |
4 | * The driver performs Copy-Before-Write (CBW) operation: it is injected above | |
5 | * some node, and before each write it copies _old_ data to the target node. | |
6 | * | |
7 | * Copyright (c) 2018-2019 Virtuozzo International GmbH. | |
8 | * | |
9 | * Author: | |
10 | * Sementsov-Ogievskiy Vladimir <vsementsov@virtuozzo.com> | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
16 | * | |
17 | * This program is distributed in the hope that it will be useful, | |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU General Public License | |
23 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
24 | */ | |
25 | ||
26 | #include "qemu/osdep.h" | |
27 | ||
28 | #include "sysemu/block-backend.h" | |
29 | #include "qemu/cutils.h" | |
30 | #include "qapi/error.h" | |
31 | #include "block/block_int.h" | |
32 | #include "block/qdict.h" | |
33 | #include "block/block-copy.h" | |
34 | ||
35 | #include "block/backup-top.h" | |
36 | ||
37 | typedef struct BDRVBackupTopState { | |
38 | BlockCopyState *bcs; | |
39 | BdrvChild *target; | |
40 | bool active; | |
397f4e9d | 41 | int64_t cluster_size; |
7df7868b VSO |
42 | } BDRVBackupTopState; |
43 | ||
44 | static coroutine_fn int backup_top_co_preadv( | |
45 | BlockDriverState *bs, uint64_t offset, uint64_t bytes, | |
46 | QEMUIOVector *qiov, int flags) | |
47 | { | |
705dde27 HR |
48 | BDRVBackupTopState *s = bs->opaque; |
49 | ||
50 | if (!s->active) { | |
51 | return -EIO; | |
52 | } | |
53 | ||
7df7868b VSO |
54 | return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); |
55 | } | |
56 | ||
57 | static coroutine_fn int backup_top_cbw(BlockDriverState *bs, uint64_t offset, | |
4bc267a7 | 58 | uint64_t bytes, BdrvRequestFlags flags) |
7df7868b | 59 | { |
00e30f05 | 60 | BDRVBackupTopState *s = bs->opaque; |
4bc267a7 VSO |
61 | uint64_t off, end; |
62 | ||
705dde27 HR |
63 | if (!s->active) { |
64 | return -EIO; | |
65 | } | |
66 | ||
4bc267a7 VSO |
67 | if (flags & BDRV_REQ_WRITE_UNCHANGED) { |
68 | return 0; | |
69 | } | |
70 | ||
397f4e9d VSO |
71 | off = QEMU_ALIGN_DOWN(offset, s->cluster_size); |
72 | end = QEMU_ALIGN_UP(offset + bytes, s->cluster_size); | |
7df7868b | 73 | |
143a6384 | 74 | return block_copy(s->bcs, off, end - off, true); |
7df7868b VSO |
75 | } |
76 | ||
77 | static int coroutine_fn backup_top_co_pdiscard(BlockDriverState *bs, | |
78 | int64_t offset, int bytes) | |
79 | { | |
4bc267a7 | 80 | int ret = backup_top_cbw(bs, offset, bytes, 0); |
7df7868b VSO |
81 | if (ret < 0) { |
82 | return ret; | |
83 | } | |
84 | ||
85 | return bdrv_co_pdiscard(bs->backing, offset, bytes); | |
86 | } | |
87 | ||
88 | static int coroutine_fn backup_top_co_pwrite_zeroes(BlockDriverState *bs, | |
89 | int64_t offset, int bytes, BdrvRequestFlags flags) | |
90 | { | |
4bc267a7 | 91 | int ret = backup_top_cbw(bs, offset, bytes, flags); |
7df7868b VSO |
92 | if (ret < 0) { |
93 | return ret; | |
94 | } | |
95 | ||
96 | return bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); | |
97 | } | |
98 | ||
99 | static coroutine_fn int backup_top_co_pwritev(BlockDriverState *bs, | |
100 | uint64_t offset, | |
101 | uint64_t bytes, | |
102 | QEMUIOVector *qiov, int flags) | |
103 | { | |
4bc267a7 VSO |
104 | int ret = backup_top_cbw(bs, offset, bytes, flags); |
105 | if (ret < 0) { | |
106 | return ret; | |
7df7868b VSO |
107 | } |
108 | ||
109 | return bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); | |
110 | } | |
111 | ||
112 | static int coroutine_fn backup_top_co_flush(BlockDriverState *bs) | |
113 | { | |
114 | if (!bs->backing) { | |
115 | return 0; | |
116 | } | |
117 | ||
118 | return bdrv_co_flush(bs->backing->bs); | |
119 | } | |
120 | ||
121 | static void backup_top_refresh_filename(BlockDriverState *bs) | |
122 | { | |
123 | if (bs->backing == NULL) { | |
124 | /* | |
125 | * we can be here after failed bdrv_attach_child in | |
126 | * bdrv_set_backing_hd | |
127 | */ | |
128 | return; | |
129 | } | |
130 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), | |
131 | bs->backing->bs->filename); | |
132 | } | |
133 | ||
134 | static void backup_top_child_perm(BlockDriverState *bs, BdrvChild *c, | |
bf8e925e | 135 | BdrvChildRole role, |
7df7868b VSO |
136 | BlockReopenQueue *reopen_queue, |
137 | uint64_t perm, uint64_t shared, | |
138 | uint64_t *nperm, uint64_t *nshared) | |
139 | { | |
140 | BDRVBackupTopState *s = bs->opaque; | |
141 | ||
142 | if (!s->active) { | |
143 | /* | |
144 | * The filter node may be in process of bdrv_append(), which firstly do | |
145 | * bdrv_set_backing_hd() and then bdrv_replace_node(). This means that | |
146 | * we can't unshare BLK_PERM_WRITE during bdrv_append() operation. So, | |
147 | * let's require nothing during bdrv_append() and refresh permissions | |
148 | * after it (see bdrv_backup_top_append()). | |
149 | */ | |
150 | *nperm = 0; | |
151 | *nshared = BLK_PERM_ALL; | |
152 | return; | |
153 | } | |
154 | ||
25191e5f | 155 | if (!(role & BDRV_CHILD_FILTERED)) { |
7df7868b VSO |
156 | /* |
157 | * Target child | |
158 | * | |
159 | * Share write to target (child_file), to not interfere | |
160 | * with guest writes to its disk which may be in target backing chain. | |
958a04bd KW |
161 | * Can't resize during a backup block job because we check the size |
162 | * only upfront. | |
7df7868b | 163 | */ |
958a04bd | 164 | *nshared = BLK_PERM_ALL & ~BLK_PERM_RESIZE; |
7df7868b VSO |
165 | *nperm = BLK_PERM_WRITE; |
166 | } else { | |
167 | /* Source child */ | |
e5d8a406 | 168 | bdrv_default_perms(bs, c, role, reopen_queue, |
69dca43d | 169 | perm, shared, nperm, nshared); |
7df7868b VSO |
170 | |
171 | if (perm & BLK_PERM_WRITE) { | |
172 | *nperm = *nperm | BLK_PERM_CONSISTENT_READ; | |
173 | } | |
958a04bd | 174 | *nshared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE); |
7df7868b VSO |
175 | } |
176 | } | |
177 | ||
178 | BlockDriver bdrv_backup_top_filter = { | |
179 | .format_name = "backup-top", | |
180 | .instance_size = sizeof(BDRVBackupTopState), | |
181 | ||
182 | .bdrv_co_preadv = backup_top_co_preadv, | |
183 | .bdrv_co_pwritev = backup_top_co_pwritev, | |
184 | .bdrv_co_pwrite_zeroes = backup_top_co_pwrite_zeroes, | |
185 | .bdrv_co_pdiscard = backup_top_co_pdiscard, | |
186 | .bdrv_co_flush = backup_top_co_flush, | |
187 | ||
7df7868b VSO |
188 | .bdrv_refresh_filename = backup_top_refresh_filename, |
189 | ||
190 | .bdrv_child_perm = backup_top_child_perm, | |
191 | ||
192 | .is_filter = true, | |
193 | }; | |
194 | ||
195 | BlockDriverState *bdrv_backup_top_append(BlockDriverState *source, | |
196 | BlockDriverState *target, | |
197 | const char *filter_node_name, | |
198 | uint64_t cluster_size, | |
86c6a3b6 | 199 | BackupPerf *perf, |
7df7868b VSO |
200 | BdrvRequestFlags write_flags, |
201 | BlockCopyState **bcs, | |
202 | Error **errp) | |
203 | { | |
934aee14 VSO |
204 | ERRP_GUARD(); |
205 | int ret; | |
7df7868b | 206 | BDRVBackupTopState *state; |
958a04bd | 207 | BlockDriverState *top; |
0df62f45 | 208 | bool appended = false; |
7df7868b | 209 | |
958a04bd KW |
210 | assert(source->total_sectors == target->total_sectors); |
211 | ||
212 | top = bdrv_new_open_driver(&bdrv_backup_top_filter, filter_node_name, | |
213 | BDRV_O_RDWR, errp); | |
7df7868b VSO |
214 | if (!top) { |
215 | return NULL; | |
216 | } | |
217 | ||
fb574de8 | 218 | state = top->opaque; |
4bc267a7 VSO |
219 | top->total_sectors = source->total_sectors; |
220 | top->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED | | |
221 | (BDRV_REQ_FUA & source->supported_write_flags); | |
222 | top->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | | |
223 | ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) & | |
224 | source->supported_zero_flags); | |
7df7868b VSO |
225 | |
226 | bdrv_ref(target); | |
58944401 HR |
227 | state->target = bdrv_attach_child(top, target, "target", &child_of_bds, |
228 | BDRV_CHILD_DATA, errp); | |
7df7868b VSO |
229 | if (!state->target) { |
230 | bdrv_unref(target); | |
231 | bdrv_unref(top); | |
232 | return NULL; | |
233 | } | |
234 | ||
235 | bdrv_drained_begin(source); | |
236 | ||
934aee14 VSO |
237 | ret = bdrv_append(top, source, errp); |
238 | if (ret < 0) { | |
239 | error_prepend(errp, "Cannot append backup-top filter: "); | |
0df62f45 | 240 | goto fail; |
7df7868b | 241 | } |
0df62f45 | 242 | appended = true; |
7df7868b VSO |
243 | |
244 | /* | |
245 | * bdrv_append() finished successfully, now we can require permissions | |
246 | * we want. | |
247 | */ | |
248 | state->active = true; | |
934aee14 VSO |
249 | ret = bdrv_child_refresh_perms(top, top->backing, errp); |
250 | if (ret < 0) { | |
251 | error_prepend(errp, "Cannot set permissions for backup-top filter: "); | |
0df62f45 | 252 | goto fail; |
7df7868b VSO |
253 | } |
254 | ||
397f4e9d | 255 | state->cluster_size = cluster_size; |
00e30f05 | 256 | state->bcs = block_copy_state_new(top->backing, state->target, |
86c6a3b6 | 257 | cluster_size, perf->use_copy_range, |
934aee14 VSO |
258 | write_flags, errp); |
259 | if (!state->bcs) { | |
260 | error_prepend(errp, "Cannot create block-copy-state: "); | |
0df62f45 | 261 | goto fail; |
7df7868b VSO |
262 | } |
263 | *bcs = state->bcs; | |
264 | ||
265 | bdrv_drained_end(source); | |
266 | ||
267 | return top; | |
268 | ||
0df62f45 VSO |
269 | fail: |
270 | if (appended) { | |
271 | state->active = false; | |
272 | bdrv_backup_top_drop(top); | |
273 | } else { | |
274 | bdrv_unref(top); | |
275 | } | |
7df7868b | 276 | |
7df7868b | 277 | bdrv_drained_end(source); |
7df7868b VSO |
278 | |
279 | return NULL; | |
280 | } | |
281 | ||
282 | void bdrv_backup_top_drop(BlockDriverState *bs) | |
283 | { | |
284 | BDRVBackupTopState *s = bs->opaque; | |
7df7868b VSO |
285 | |
286 | bdrv_drained_begin(bs); | |
287 | ||
503ca126 HR |
288 | block_copy_state_free(s->bcs); |
289 | ||
7df7868b VSO |
290 | s->active = false; |
291 | bdrv_child_refresh_perms(bs, bs->backing, &error_abort); | |
2b088c60 | 292 | bdrv_replace_node(bs, bs->backing->bs, &error_abort); |
7df7868b VSO |
293 | bdrv_set_backing_hd(bs, NULL, &error_abort); |
294 | ||
295 | bdrv_drained_end(bs); | |
296 | ||
297 | bdrv_unref(bs); | |
7df7868b | 298 | } |