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[PATCH qemu 2/4] drive-mirror: add support for conditional and always bi
From: |
Fabian Grünbichler |
Subject: |
[PATCH qemu 2/4] drive-mirror: add support for conditional and always bitmap sync modes |
Date: |
Tue, 22 Sep 2020 11:14:16 +0200 |
From: John Snow <jsnow@redhat.com>
Teach mirror two new tricks for using bitmaps:
Always: no matter what, we synchronize the copy_bitmap back to the
sync_bitmap. In effect, this allows us resume a failed mirror at a later
date, since the target bdrv should be exactly in the state referenced by
the bitmap.
Conditional: On success only, we sync the bitmap. This is akin to
incremental backup modes; we can use this bitmap to later refresh a
successfully created mirror, or possibly re-try the whole failed mirror
if we are able to rollback the target to the state before starting the
mirror.
Based on original work by John Snow.
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---
block/mirror.c | 28 ++++++++++++++++++++--------
blockdev.c | 3 +++
2 files changed, 23 insertions(+), 8 deletions(-)
diff --git a/block/mirror.c b/block/mirror.c
index d64c8203ef..bc4f4563d9 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -654,8 +654,6 @@ static int mirror_exit_common(Job *job)
bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs);
}
- bdrv_release_dirty_bitmap(s->dirty_bitmap);
-
/* Make sure that the source BDS doesn't go away during bdrv_replace_node,
* before we can call bdrv_drained_end */
bdrv_ref(src);
@@ -755,6 +753,18 @@ static int mirror_exit_common(Job *job)
blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);
blk_insert_bs(bjob->blk, mirror_top_bs, &error_abort);
+ if (s->sync_bitmap) {
+ if (s->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS ||
+ (s->bitmap_mode == BITMAP_SYNC_MODE_ON_SUCCESS &&
+ job->ret == 0 && ret == 0)) {
+ /* Success; synchronize copy back to sync. */
+ bdrv_clear_dirty_bitmap(s->sync_bitmap, NULL);
+ bdrv_dirty_bitmap_merge_internal(s->sync_bitmap, s->dirty_bitmap,
+ NULL, true);
+ }
+ }
+ bdrv_release_dirty_bitmap(s->dirty_bitmap);
+
bs_opaque->job = NULL;
bdrv_drained_end(src);
@@ -1592,10 +1602,6 @@ static BlockJob *mirror_start_job(
" sync mode",
MirrorSyncMode_str(sync_mode));
return NULL;
- } else if (bitmap_mode != BITMAP_SYNC_MODE_NEVER) {
- error_setg(errp,
- "Bitmap Sync Mode '%s' is not supported by Mirror",
- BitmapSyncMode_str(bitmap_mode));
}
} else if (bitmap) {
error_setg(errp,
@@ -1612,6 +1618,12 @@ static BlockJob *mirror_start_job(
return NULL;
}
granularity = bdrv_dirty_bitmap_granularity(bitmap);
+
+ if (bitmap_mode != BITMAP_SYNC_MODE_NEVER) {
+ if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) {
+ return NULL;
+ }
+ }
} else if (granularity == 0) {
granularity = bdrv_get_default_bitmap_granularity(target);
}
@@ -1781,8 +1793,8 @@ static BlockJob *mirror_start_job(
}
if (s->sync_mode == MIRROR_SYNC_MODE_BITMAP) {
- bdrv_merge_dirty_bitmap(s->dirty_bitmap, s->sync_bitmap,
- NULL, &local_err);
+ bdrv_dirty_bitmap_merge_internal(s->dirty_bitmap, s->sync_bitmap,
+ NULL, true);
if (local_err) {
goto fail;
}
diff --git a/blockdev.c b/blockdev.c
index 6baa1a33f5..0fd30a392d 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3019,6 +3019,9 @@ static void blockdev_mirror_common(const char *job_id,
BlockDriverState *bs,
if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
return;
}
+ } else if (has_bitmap_mode) {
+ error_setg(errp, "Cannot specify bitmap sync mode without a bitmap");
+ return;
}
if (!has_replaces) {
--
2.20.1