Commit 50824995 authored by Fam Zheng's avatar Fam Zheng Committed by Stefan Hajnoczi
Browse files

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: default avatar <wangxiaolong@ucloud.cn>
Signed-off-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent dcfb3beb

block/io.c

+2 −2
Original line number Diff line number Diff line
@@ -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;