From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55743) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d4Cb7-0001xX-AZ for qemu-devel@nongnu.org; Fri, 28 Apr 2017 16:34:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d4Cb6-0001LA-Cz for qemu-devel@nongnu.org; Fri, 28 Apr 2017 16:34:37 -0400 From: Kevin Wolf Date: Fri, 28 Apr 2017 22:33:27 +0200 Message-Id: <1493411622-5343-20-git-send-email-kwolf@redhat.com> In-Reply-To: <1493411622-5343-1-git-send-email-kwolf@redhat.com> References: <1493411622-5343-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 19/34] block: fix alignment calculations in bdrv_co_do_zero_pwritev 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" tail_padding_bytes is calculated wrong. F.e. for offset = 0 bytes = 2048 align = 512 we will have tail_padding_bytes = 512 which is definitely wrong. The patch fixes that arithmetics. Fortunately this problem is harmless, we will have 1 extra allocation and free thus there is no need to put this into stable. The problem is here from the very beginning. Signed-off-by: Denis V. Lunev CC: Stefan Hajnoczi CC: Fam Zheng Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- block/io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/io.c b/block/io.c index 80d6c62..40bd94f 100644 --- a/block/io.c +++ b/block/io.c @@ -1444,7 +1444,7 @@ static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child, int ret = 0; head_padding_bytes = offset & (align - 1); - tail_padding_bytes = align - ((offset + bytes) & (align - 1)); + tail_padding_bytes = (align - (offset + bytes)) & (align - 1); assert(flags & BDRV_REQ_ZERO_WRITE); -- 1.8.3.1