From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:32897) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGDFw-0004Rd-GG for qemu-devel@nongnu.org; Thu, 23 Jun 2016 18:37:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bGDFq-0005wz-RI for qemu-devel@nongnu.org; Thu, 23 Jun 2016 18:37:51 -0400 From: Eric Blake Date: Thu, 23 Jun 2016 16:37:07 -0600 Message-Id: <1466721446-27737-4-git-send-email-eblake@redhat.com> In-Reply-To: <1466721446-27737-1-git-send-email-eblake@redhat.com> References: <1466721446-27737-1-git-send-email-eblake@redhat.com> Subject: [Qemu-devel] [PATCH v3 03/22] block: Fix harmless off-by-one in bdrv_aligned_preadv() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, kwolf@redhat.com, famz@redhat.com, stefanha@redhat.com, Max Reitz If the amount of data to read ends exactly on the total size of the bs, then we were wasting time creating a local qiov to read the data in preparation for what would normally be appending zeroes beyond the end, even though this corner case has nothing further to do. Signed-off-by: Eric Blake Reviewed-by: Kevin Wolf Reviewed-by: Fam Zheng Reviewed-by: Stefan Hajnoczi --- v3: no change v2: no change, add R-b --- block/io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/io.c b/block/io.c index 994d3fa..82c9ff0 100644 --- a/block/io.c +++ b/block/io.c @@ -1036,7 +1036,7 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs, } max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align); - if (bytes < max_bytes) { + if (bytes <= max_bytes) { ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0); } else if (max_bytes > 0) { QEMUIOVector local_qiov; -- 2.5.5