From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43675) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2iDO-0006kt-37 for qemu-devel@nongnu.org; Tue, 17 May 2016 12:51:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b2iDN-0007HA-0Q for qemu-devel@nongnu.org; Tue, 17 May 2016 12:51:25 -0400 From: Kevin Wolf Date: Tue, 17 May 2016 18:51:02 +0200 Message-Id: <1463503863-19009-3-git-send-email-kwolf@redhat.com> In-Reply-To: <1463503863-19009-1-git-send-email-kwolf@redhat.com> References: <1463503863-19009-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 2/3] qcow2: Fix write_zeroes with partially allocated backing file cluster List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, mreitz@redhat.com, eblake@redhat.com, den@openvz.org, qemu-devel@nongnu.org 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 --- block/qcow2.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/qcow2.c b/block/qcow2.c index a6012dc..c197ff3 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; } -- 1.8.3.1