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block: Fix dirty bitmap in bdrv_co_discard 

Unsetting dirty globally with discard is not very correct. The discard may zero
out sectors (depending on can_write_zeroes_with_unmap), we should replicate
this change to destination side to make sure that the guest sees the same data.

Calling bdrv_reset_dirty also troubles mirror job because the hbitmap iterator
doesn't expect unsetting of bits after current position.

So let's do it the opposite way which fixes both problems: set the dirty bits
if we are to discard it.

Reported-by: wangxiaolong@ucloud.cn
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 508249952c)
Conflicts:
	block/io.c

* applied manually to avoid dependency on 61007b316
* squashed in 6e82e4b bdrv_reset_dirty() is static in
  2.3.0 and becomes unused as of this patch
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
This commit is contained in:
Fam Zheng 2015-06-08 13:56:10 +08:00 committed by Michael Roth
parent 27ed14c4d7
commit 3d8b7aed60
1 changed files with 2 additions and 13 deletions
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15
block.c
View File

@ -99,8 +99,6 @@ static QLIST_HEAD(, BlockDriver) bdrv_drivers =
static void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
int nr_sectors);
static void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
int nr_sectors);
/* If non-zero, use only whitelisted block drivers */
static int use_bdrv_whitelist;
@ -5299,8 +5297,6 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
return -EROFS;
}
bdrv_reset_dirty(bs, sector_num, nb_sectors);
/* Do nothing if disabled. */
if (!(bs->open_flags & BDRV_O_UNMAP)) {
return 0;
@ -5310,6 +5306,8 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
return 0;
}
bdrv_set_dirty(bs, sector_num, nb_sectors);
max_discard = MIN_NON_ZERO(bs->bl.max_discard, BDRV_REQUEST_MAX_SECTORS);
while (nb_sectors > 0) {
int ret;
@ -5620,15 +5618,6 @@ static void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
}
}
static void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
int nr_sectors)
{
BdrvDirtyBitmap *bitmap;
QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
hbitmap_reset(bitmap->bitmap, cur_sector, nr_sectors);
}
}
int64_t bdrv_get_dirty_count(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
{
return hbitmap_count(bitmap->bitmap);