From 5efdf53227809a0da436dd63d7ed19c99044ecbd Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Tue, 17 May 2016 18:42:23 +0200 Subject: 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: Kevin Wolf Reviewed-by: Eric Blake Reviewed-by: Denis V. Lunev --- block/qcow2.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'block') diff --git a/block/qcow2.c b/block/qcow2.c index a6012dc793..c197ff3c53 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -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; } -- cgit v1.2.3