blob: 67ea339da992835dcc46f3384945a48117d3da82 [file] [log] [blame]
Vladimir Sementsov-Ogievskiy1c14eaa2022-03-03 20:43:44 +01001/*
2 * snapshot_access block driver
3 *
4 * Copyright (c) 2022 Virtuozzo International GmbH.
5 *
6 * Author:
7 * Sementsov-Ogievskiy Vladimir <vsementsov@virtuozzo.com>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 */
22
23#include "qemu/osdep.h"
24
25#include "sysemu/block-backend.h"
26#include "qemu/cutils.h"
27#include "block/block_int.h"
28
Kevin Wolf7b9e8b22023-02-03 16:21:54 +010029static int coroutine_fn GRAPH_RDLOCK
Vladimir Sementsov-Ogievskiy1c14eaa2022-03-03 20:43:44 +010030snapshot_access_co_preadv_part(BlockDriverState *bs,
31 int64_t offset, int64_t bytes,
32 QEMUIOVector *qiov, size_t qiov_offset,
33 BdrvRequestFlags flags)
34{
35 if (flags) {
36 return -ENOTSUP;
37 }
38
39 return bdrv_co_preadv_snapshot(bs->file, offset, bytes, qiov, qiov_offset);
40}
41
Kevin Wolf7b9e8b22023-02-03 16:21:54 +010042static int coroutine_fn GRAPH_RDLOCK
Vladimir Sementsov-Ogievskiy1c14eaa2022-03-03 20:43:44 +010043snapshot_access_co_block_status(BlockDriverState *bs,
44 bool want_zero, int64_t offset,
45 int64_t bytes, int64_t *pnum,
46 int64_t *map, BlockDriverState **file)
47{
48 return bdrv_co_snapshot_block_status(bs->file->bs, want_zero, offset,
49 bytes, pnum, map, file);
50}
51
Emanuele Giuseppe Esposito9a5a1c62023-02-03 16:21:47 +010052static int coroutine_fn GRAPH_RDLOCK
53snapshot_access_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
Vladimir Sementsov-Ogievskiy1c14eaa2022-03-03 20:43:44 +010054{
55 return bdrv_co_pdiscard_snapshot(bs->file->bs, offset, bytes);
56}
57
58static int coroutine_fn
59snapshot_access_co_pwrite_zeroes(BlockDriverState *bs,
60 int64_t offset, int64_t bytes,
61 BdrvRequestFlags flags)
62{
63 return -ENOTSUP;
64}
65
66static coroutine_fn int
67snapshot_access_co_pwritev_part(BlockDriverState *bs,
68 int64_t offset, int64_t bytes,
69 QEMUIOVector *qiov, size_t qiov_offset,
70 BdrvRequestFlags flags)
71{
72 return -ENOTSUP;
73}
74
75
76static void snapshot_access_refresh_filename(BlockDriverState *bs)
77{
78 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
79 bs->file->bs->filename);
80}
81
82static int snapshot_access_open(BlockDriverState *bs, QDict *options, int flags,
83 Error **errp)
84{
Vladimir Sementsov-Ogievskiy5bb047472022-07-26 23:11:32 +030085 bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
86 BDRV_CHILD_DATA | BDRV_CHILD_PRIMARY,
87 false, errp);
Vladimir Sementsov-Ogievskiy1c14eaa2022-03-03 20:43:44 +010088 if (!bs->file) {
89 return -EINVAL;
90 }
91
92 bs->total_sectors = bs->file->bs->total_sectors;
93
94 return 0;
95}
96
97static void snapshot_access_child_perm(BlockDriverState *bs, BdrvChild *c,
98 BdrvChildRole role,
99 BlockReopenQueue *reopen_queue,
100 uint64_t perm, uint64_t shared,
101 uint64_t *nperm, uint64_t *nshared)
102{
103 /*
104 * Currently, we don't need any permissions. If bs->file provides
105 * snapshot-access API, we can use it.
106 */
107 *nperm = 0;
108 *nshared = BLK_PERM_ALL;
109}
110
111BlockDriver bdrv_snapshot_access_drv = {
112 .format_name = "snapshot-access",
113
114 .bdrv_open = snapshot_access_open,
115
116 .bdrv_co_preadv_part = snapshot_access_co_preadv_part,
117 .bdrv_co_pwritev_part = snapshot_access_co_pwritev_part,
118 .bdrv_co_pwrite_zeroes = snapshot_access_co_pwrite_zeroes,
119 .bdrv_co_pdiscard = snapshot_access_co_pdiscard,
120 .bdrv_co_block_status = snapshot_access_co_block_status,
121
122 .bdrv_refresh_filename = snapshot_access_refresh_filename,
123
124 .bdrv_child_perm = snapshot_access_child_perm,
125};
126
127static void snapshot_access_init(void)
128{
129 bdrv_register(&bdrv_snapshot_access_drv);
130}
131
132block_init(snapshot_access_init);