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mirror: Fix bdrv_has_zero_init() use

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bdrv_has_zero_init() only has meaning for newly created images or image
areas.  If the mirror job itself did not create the image, it cannot
rely on bdrv_has_zero_init()'s result to carry any meaning.

This is the case for drive-mirror with mode=existing and always for
blockdev-mirror.

Note that we only have to zero-initialize the target with sync=full,
because other modes actually do not promise that the target will contain
the same data as the source after the job -- sync=top only promises to
copy anything allocated in the top layer, and sync=none will only copy
new I/O.  (Which is how mirror has always handled it.)

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190724171239.8764-3-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2019-07-24 19:12:30 +02:00
parent 4d7c487eac
commit cdf3bc934a
4 changed files with 24 additions and 7 deletions
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11
block/mirror.c
View file

@ -51,6 +51,8 @@ typedef struct MirrorBlockJob {
Error *replace_blocker;
bool is_none_mode;
BlockMirrorBackingMode backing_mode;
/* Whether the target image requires explicit zero-initialization */
bool zero_target;
MirrorCopyMode copy_mode;
BlockdevOnError on_source_error, on_target_error;
bool synced;
@ -767,7 +769,7 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
int ret;
int64_t count;
if (base == NULL && !bdrv_has_zero_init(target_bs)) {
if (s->zero_target) {
if (!bdrv_can_write_zeroes_with_unmap(target_bs)) {
bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length);
return 0;
@ -1515,6 +1517,7 @@ static BlockJob *mirror_start_job(
const char *replaces, int64_t speed,
uint32_t granularity, int64_t buf_size,
BlockMirrorBackingMode backing_mode,
bool zero_target,
BlockdevOnError on_source_error,
BlockdevOnError on_target_error,
bool unmap,
@ -1643,6 +1646,7 @@ static BlockJob *mirror_start_job(
s->on_target_error = on_target_error;
s->is_none_mode = is_none_mode;
s->backing_mode = backing_mode;
s->zero_target = zero_target;
s->copy_mode = copy_mode;
s->base = base;
s->granularity = granularity;
@ -1747,6 +1751,7 @@ void mirror_start(const char *job_id, BlockDriverState *bs,
int creation_flags, int64_t speed,
uint32_t granularity, int64_t buf_size,
MirrorSyncMode mode, BlockMirrorBackingMode backing_mode,
bool zero_target,
BlockdevOnError on_source_error,
BlockdevOnError on_target_error,
bool unmap, const char *filter_node_name,
@ -1764,7 +1769,7 @@ void mirror_start(const char *job_id, BlockDriverState *bs,
is_none_mode = mode == MIRROR_SYNC_MODE_NONE;
base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL;
mirror_start_job(job_id, bs, creation_flags, target, replaces,
speed, granularity, buf_size, backing_mode,
speed, granularity, buf_size, backing_mode, zero_target,
on_source_error, on_target_error, unmap, NULL, NULL,
&mirror_job_driver, is_none_mode, base, false,
filter_node_name, true, copy_mode, errp);
@ -1791,7 +1796,7 @@ BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs,
ret = mirror_start_job(
job_id, bs, creation_flags, base, NULL, speed, 0, 0,
MIRROR_LEAVE_BACKING_CHAIN,
MIRROR_LEAVE_BACKING_CHAIN, false,
on_error, on_error, true, cb, opaque,
&commit_active_job_driver, false, base, auto_complete,
filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND,