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qemu/mirror-Fix-bdrv_has_zero_init-use.patch
Chen Qun 19b8d6bdf3 mirror: Fix bdrv_has_zero_init() use 
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>
2021-07-22 21:28:34 +08:00

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From 7fcb1c1a956a8cad5c2e8585e53878edc4fd9eca Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Wed, 24 Jul 2019 19:12:30 +0200
Subject: [PATCH] mirror: Fix bdrv_has_zero_init() use
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>
---
block/mirror.c | 11 ++++++++---
blockdev.c | 16 +++++++++++++---
include/block/block_int.h | 2 ++
tests/test-block-iothread.c | 2 +-
4 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/block/mirror.c b/block/mirror.c
index ccae49a28e..89a053b265 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -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;
@@ -779,7 +781,7 @@ 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;
@@ -1531,6 +1533,7 @@ 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,
@@ -1658,6 +1661,7 @@ 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;
@@ -1762,6 +1766,7 @@ 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,
@@ -1779,7 +1784,7 @@ 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);
@@ -1806,7 +1811,7 @@ 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,
diff --git a/blockdev.c b/blockdev.c
index 94e5aee30b..4435795b6d 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3739,6 +3739,7 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
bool has_replaces, const char *replaces,
enum MirrorSyncMode sync,
BlockMirrorBackingMode backing_mode,
+ bool zero_target,
bool has_speed, int64_t speed,
bool has_granularity, uint32_t granularity,
bool has_buf_size, int64_t buf_size,
@@ -3847,7 +3848,7 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
*/
mirror_start(job_id, bs, target,
has_replaces ? replaces : NULL, job_flags,
- speed, granularity, buf_size, sync, backing_mode,
+ speed, granularity, buf_size, sync, backing_mode, zero_target,
on_source_error, on_target_error, unmap, filter_node_name,
copy_mode, errp);
}
@@ -3863,6 +3864,7 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
int flags;
int64_t size;
const char *format = arg->format;
+ bool zero_target;
int ret;
bs = qmp_get_root_bs(arg->device, errp);
@@ -3964,6 +3966,10 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
goto out;
}
+ zero_target = (arg->sync == MIRROR_SYNC_MODE_FULL &&
+ (arg->mode == NEW_IMAGE_MODE_EXISTING ||
+ !bdrv_has_zero_init(target_bs)));
+
ret = bdrv_try_set_aio_context(target_bs, aio_context, errp);
if (ret < 0) {
bdrv_unref(target_bs);
@@ -3972,7 +3978,8 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
blockdev_mirror_common(arg->has_job_id ? arg->job_id : NULL, bs, target_bs,
arg->has_replaces, arg->replaces, arg->sync,
- backing_mode, arg->has_speed, arg->speed,
+ backing_mode, zero_target,
+ arg->has_speed, arg->speed,
arg->has_granularity, arg->granularity,
arg->has_buf_size, arg->buf_size,
arg->has_on_source_error, arg->on_source_error,
@@ -4012,6 +4019,7 @@ void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
AioContext *aio_context;
BlockMirrorBackingMode backing_mode = MIRROR_LEAVE_BACKING_CHAIN;
Error *local_err = NULL;
+ bool zero_target;
int ret;
bs = qmp_get_root_bs(device, errp);
@@ -4024,6 +4032,8 @@ void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
return;
}
+ zero_target = (sync == MIRROR_SYNC_MODE_FULL);
+
aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
@@ -4034,7 +4044,7 @@ void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
blockdev_mirror_common(has_job_id ? job_id : NULL, bs, target_bs,
has_replaces, replaces, sync, backing_mode,
- has_speed, speed,
+ zero_target, has_speed, speed,
has_granularity, granularity,
has_buf_size, buf_size,
has_on_source_error, on_source_error,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 76117a761a..154b9b5501 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -1120,6 +1120,7 @@ BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs,
* @buf_size: The amount of data that can be in flight at one time.
* @mode: Whether to collapse all images in the chain to the target.
* @backing_mode: How to establish the target's backing chain after completion.
+ * @zero_target: Whether the target should be explicitly zero-initialized
* @on_source_error: The action to take upon error reading from the source.
* @on_target_error: The action to take upon error writing to the target.
* @unmap: Whether to unmap target where source sectors only contain zeroes.
@@ -1139,6 +1140,7 @@ 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,
diff --git a/tests/test-block-iothread.c b/tests/test-block-iothread.c
index 1949d5e61a..debfb69bfb 100644
--- a/tests/test-block-iothread.c
+++ b/tests/test-block-iothread.c
@@ -611,7 +611,7 @@ static void test_propagate_mirror(void)
/* Start a mirror job */
mirror_start("job0", src, target, NULL, JOB_DEFAULT, 0, 0, 0,
- MIRROR_SYNC_MODE_NONE, MIRROR_OPEN_BACKING_CHAIN,
+ MIRROR_SYNC_MODE_NONE, MIRROR_OPEN_BACKING_CHAIN, false,
BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
false, "filter_node", MIRROR_COPY_MODE_BACKGROUND,
&error_abort);
--
2.27.0
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