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block/mirror: determine copy_to_target only once

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In preparation to allow changing the copy_mode via QMP. When running
in an iothread, it could be that copy_mode is changed from the main
thread in between reading copy_mode in bdrv_mirror_top_pwritev() and
reading copy_mode in bdrv_mirror_top_do_write(), so they might end up
disagreeing about whether copy_to_target is true or false. Avoid that
scenario by determining copy_to_target only once and passing it to
bdrv_mirror_top_do_write() as an argument.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20231031135431.393137-5-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Fiona Ebner 2023-10-31 14:54:25 +01:00 committed by Kevin Wolf
parent 058cfca564
commit 7b32ad2242
1 changed files with 18 additions and 23 deletions
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41
block/mirror.c
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@ -1463,21 +1463,21 @@ bdrv_mirror_top_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
}
static bool should_copy_to_target(MirrorBDSOpaque *s)
{
return s->job && s->job->ret >= 0 &&
!job_is_cancelled(&s->job->common.job) &&
s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING;
}
static int coroutine_fn GRAPH_RDLOCK
bdrv_mirror_top_do_write(BlockDriverState *bs, MirrorMethod method,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov,
int flags)
bool copy_to_target, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
MirrorOp *op = NULL;
MirrorBDSOpaque *s = bs->opaque;
int ret = 0;
bool copy_to_target = false;
if (s->job) {
copy_to_target = s->job->ret >= 0 &&
!job_is_cancelled(&s->job->common.job) &&
s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING;
}
if (copy_to_target) {
op = active_write_prepare(s->job, offset, bytes);
@ -1524,17 +1524,10 @@ static int coroutine_fn GRAPH_RDLOCK
bdrv_mirror_top_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, BdrvRequestFlags flags)
{
MirrorBDSOpaque *s = bs->opaque;
QEMUIOVector bounce_qiov;
void *bounce_buf;
int ret = 0;
bool copy_to_target = false;
if (s->job) {
copy_to_target = s->job->ret >= 0 &&
!job_is_cancelled(&s->job->common.job) &&
s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING;
}
bool copy_to_target = should_copy_to_target(bs->opaque);
if (copy_to_target) {
/* The guest might concurrently modify the data to write; but
@ -1551,8 +1544,8 @@ bdrv_mirror_top_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
flags &= ~BDRV_REQ_REGISTERED_BUF;
}
ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov,
flags);
ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, copy_to_target,
offset, bytes, qiov, flags);
if (copy_to_target) {
qemu_iovec_destroy(&bounce_qiov);
@ -1575,15 +1568,17 @@ static int coroutine_fn GRAPH_RDLOCK
bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
int64_t bytes, BdrvRequestFlags flags)
{
return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL,
flags);
bool copy_to_target = should_copy_to_target(bs->opaque);
return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, copy_to_target,
offset, bytes, NULL, flags);
}
static int coroutine_fn GRAPH_RDLOCK
bdrv_mirror_top_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
{
return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes,
NULL, 0);
bool copy_to_target = should_copy_to_target(bs->opaque);
return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, copy_to_target,
offset, bytes, NULL, 0);
}
static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs)