1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
|
/*
* Copy-on-read filter block driver
*
* Copyright (c) 2018 Red Hat, Inc.
*
* Author:
* Max Reitz <mreitz@redhat.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 or
* (at your option) version 3 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "block/block_int.h"
#include "qemu/module.h"
static int cor_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
false, errp);
if (!bs->file) {
return -EINVAL;
}
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
(BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
bs->file->bs->supported_zero_flags);
return 0;
}
#define PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
| BLK_PERM_WRITE \
| BLK_PERM_RESIZE)
#define PERM_UNCHANGED (BLK_PERM_ALL & ~PERM_PASSTHROUGH)
static void cor_child_perm(BlockDriverState *bs, BdrvChild *c,
BdrvChildRole role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
*nperm = perm & PERM_PASSTHROUGH;
*nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED;
/* We must not request write permissions for an inactive node, the child
* cannot provide it. */
if (!(bs->open_flags & BDRV_O_INACTIVE)) {
*nperm |= BLK_PERM_WRITE_UNCHANGED;
}
}
static int64_t cor_getlength(BlockDriverState *bs)
{
return bdrv_getlength(bs->file->bs);
}
static int coroutine_fn cor_co_preadv(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
return bdrv_co_preadv(bs->file, offset, bytes, qiov,
flags | BDRV_REQ_COPY_ON_READ);
}
static int coroutine_fn cor_co_pwritev(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
}
static int coroutine_fn cor_co_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int bytes,
BdrvRequestFlags flags)
{
return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
}
static int coroutine_fn cor_co_pdiscard(BlockDriverState *bs,
int64_t offset, int bytes)
{
return bdrv_co_pdiscard(bs->file, offset, bytes);
}
static int coroutine_fn cor_co_pwritev_compressed(BlockDriverState *bs,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov)
{
return bdrv_co_pwritev(bs->file, offset, bytes, qiov,
BDRV_REQ_WRITE_COMPRESSED);
}
static void cor_eject(BlockDriverState *bs, bool eject_flag)
{
bdrv_eject(bs->file->bs, eject_flag);
}
static void cor_lock_medium(BlockDriverState *bs, bool locked)
{
bdrv_lock_medium(bs->file->bs, locked);
}
static BlockDriver bdrv_copy_on_read = {
.format_name = "copy-on-read",
.bdrv_open = cor_open,
.bdrv_child_perm = cor_child_perm,
.bdrv_getlength = cor_getlength,
.bdrv_co_preadv = cor_co_preadv,
.bdrv_co_pwritev = cor_co_pwritev,
.bdrv_co_pwrite_zeroes = cor_co_pwrite_zeroes,
.bdrv_co_pdiscard = cor_co_pdiscard,
.bdrv_co_pwritev_compressed = cor_co_pwritev_compressed,
.bdrv_eject = cor_eject,
.bdrv_lock_medium = cor_lock_medium,
.bdrv_co_block_status = bdrv_co_block_status_from_file,
.has_variable_length = true,
.is_filter = true,
};
static void bdrv_copy_on_read_init(void)
{
bdrv_register(&bdrv_copy_on_read);
}
block_init(bdrv_copy_on_read_init);
|
