Commit 5efdf532 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

qcow2: Fix write_zeroes with partially allocated backing file cluster 



In order to correctly check whether a given cluster is read as zero, we
don't only need to check whether bdrv_get_block_status_above() sets
BDRV_BLOCK_ZERO, but also if all sectors for the whole cluster have the
same status.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarDenis V. Lunev <den@openvz.org>
parent f575f145

block/qcow2.c

+2 −1
Original line number Diff line number Diff line
@@ -2412,7 +2412,7 @@ static bool is_zero_cluster(BlockDriverState *bs, int64_t start) 
    BlockDriverState *file;

    int64_t res = bdrv_get_block_status_above(bs, NULL, start,

                                              s->cluster_sectors, &nr, &file);

    return res >= 0 && (res & BDRV_BLOCK_ZERO);

    return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == s->cluster_sectors;

}



static bool is_zero_cluster_top_locked(BlockDriverState *bs, int64_t start)
@@ -2423,6 +2423,7 @@ static bool is_zero_cluster_top_locked(BlockDriverState *bs, int64_t start) 
    int ret;



    ret = qcow2_get_cluster_offset(bs, start << BDRV_SECTOR_BITS, &nr, &off);

    assert(nr == s->cluster_sectors);

    return ret == QCOW2_CLUSTER_UNALLOCATED || ret == QCOW2_CLUSTER_ZERO;

}