From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41746) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b3Pmp-0005bM-Rm for qemu-devel@nongnu.org; Thu, 19 May 2016 11:22:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b3Pmk-0000UA-St for qemu-devel@nongnu.org; Thu, 19 May 2016 11:22:55 -0400 From: Kevin Wolf Date: Thu, 19 May 2016 17:22:03 +0200 Message-Id: <1463671329-22655-26-git-send-email-kwolf@redhat.com> In-Reply-To: <1463671329-22655-1-git-send-email-kwolf@redhat.com> References: <1463671329-22655-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 25/31] qcow2: fix condition in is_zero_cluster List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: "Denis V. Lunev" We should check for (res & BDRV_BLOCK_ZERO) only. The situation when we will have !(res & BDRV_BLOCK_DATA) and will not have BDRV_BLOCK_ZERO is not possible for images with bdi.unallocated_blocks_are_zero == true. For those images where it's false, however, it can happen and we must not consider the data zeroed then or we would corrupt the image. Signed-off-by: Denis V. Lunev CC: Kevin Wolf Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- block/qcow2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/qcow2.c b/block/qcow2.c index 62febfc..a6012dc 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) || !(res & BDRV_BLOCK_DATA)); + return res >= 0 && (res & BDRV_BLOCK_ZERO); } static bool is_zero_cluster_top_locked(BlockDriverState *bs, int64_t start) -- 1.8.3.1