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23#include "qemu/osdep.h"
24#include "block/block_int.h"
25#include "qemu/module.h"
26
27
28static int cor_open(BlockDriverState *bs, QDict *options, int flags,
29 Error **errp)
30{
31 bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false,
32 errp);
33 if (!bs->file) {
34 return -EINVAL;
35 }
36
37 bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
38 (BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
39
40 bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
41 ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
42 bs->file->bs->supported_zero_flags);
43
44 return 0;
45}
46
47
48#define PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
49 | BLK_PERM_WRITE \
50 | BLK_PERM_RESIZE)
51#define PERM_UNCHANGED (BLK_PERM_ALL & ~PERM_PASSTHROUGH)
52
53static void cor_child_perm(BlockDriverState *bs, BdrvChild *c,
54 const BdrvChildRole *role,
55 BlockReopenQueue *reopen_queue,
56 uint64_t perm, uint64_t shared,
57 uint64_t *nperm, uint64_t *nshared)
58{
59 *nperm = perm & PERM_PASSTHROUGH;
60 *nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED;
61
62
63
64 if (!(bs->open_flags & BDRV_O_INACTIVE)) {
65 *nperm |= BLK_PERM_WRITE_UNCHANGED;
66 }
67}
68
69
70static int64_t cor_getlength(BlockDriverState *bs)
71{
72 return bdrv_getlength(bs->file->bs);
73}
74
75
76static int coroutine_fn cor_co_preadv(BlockDriverState *bs,
77 uint64_t offset, uint64_t bytes,
78 QEMUIOVector *qiov, int flags)
79{
80 return bdrv_co_preadv(bs->file, offset, bytes, qiov,
81 flags | BDRV_REQ_COPY_ON_READ);
82}
83
84
85static int coroutine_fn cor_co_pwritev(BlockDriverState *bs,
86 uint64_t offset, uint64_t bytes,
87 QEMUIOVector *qiov, int flags)
88{
89
90 return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
91}
92
93
94static int coroutine_fn cor_co_pwrite_zeroes(BlockDriverState *bs,
95 int64_t offset, int bytes,
96 BdrvRequestFlags flags)
97{
98 return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
99}
100
101
102static int coroutine_fn cor_co_pdiscard(BlockDriverState *bs,
103 int64_t offset, int bytes)
104{
105 return bdrv_co_pdiscard(bs->file, offset, bytes);
106}
107
108
109static void cor_eject(BlockDriverState *bs, bool eject_flag)
110{
111 bdrv_eject(bs->file->bs, eject_flag);
112}
113
114
115static void cor_lock_medium(BlockDriverState *bs, bool locked)
116{
117 bdrv_lock_medium(bs->file->bs, locked);
118}
119
120
121static bool cor_recurse_is_first_non_filter(BlockDriverState *bs,
122 BlockDriverState *candidate)
123{
124 return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
125}
126
127
128static BlockDriver bdrv_copy_on_read = {
129 .format_name = "copy-on-read",
130
131 .bdrv_open = cor_open,
132 .bdrv_child_perm = cor_child_perm,
133
134 .bdrv_getlength = cor_getlength,
135
136 .bdrv_co_preadv = cor_co_preadv,
137 .bdrv_co_pwritev = cor_co_pwritev,
138 .bdrv_co_pwrite_zeroes = cor_co_pwrite_zeroes,
139 .bdrv_co_pdiscard = cor_co_pdiscard,
140
141 .bdrv_eject = cor_eject,
142 .bdrv_lock_medium = cor_lock_medium,
143
144 .bdrv_co_block_status = bdrv_co_block_status_from_file,
145
146 .bdrv_recurse_is_first_non_filter = cor_recurse_is_first_non_filter,
147
148 .has_variable_length = true,
149 .is_filter = true,
150};
151
152static void bdrv_copy_on_read_init(void)
153{
154 bdrv_register(&bdrv_copy_on_read);
155}
156
157block_init(bdrv_copy_on_read_init);
158