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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>
This commit is contained in:
Fam Zheng 2015-06-08 13:56:10 +08:00 committed by Stefan Hajnoczi
parent dcfb3beb51
commit 508249952c
1 changed files with 2 additions and 2 deletions
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4
block/io.c
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@ -2412,8 +2412,6 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
return -EPERM;
}
bdrv_reset_dirty(bs, sector_num, nb_sectors);
/* Do nothing if disabled. */
if (!(bs->open_flags & BDRV_O_UNMAP)) {
return 0;
@ -2423,6 +2421,8 @@ 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;