From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=33292 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OEQRQ-0006nn-QK for qemu-devel@nongnu.org; Tue, 18 May 2010 13:19:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OEQRM-00087g-Vl for qemu-devel@nongnu.org; Tue, 18 May 2010 13:18:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19116) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OEQRM-000871-88 for qemu-devel@nongnu.org; Tue, 18 May 2010 13:18:48 -0400 From: Avi Kivity Date: Tue, 18 May 2010 20:18:44 +0300 Message-Id: <1274203124-14318-1-git-send-email-avi@redhat.com> Subject: [Qemu-devel] [PATCH +stable] block: don't attempt to merge overlapping requests List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org The block multiwrite code pretends to be able to merge overlapping requests, but doesn't do so in fact. This leads to I/O errors (for example on mkfs of a large virtio disk). Signed-off-by: Avi Kivity --- block.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index 48305b7..0e44e26 100644 --- a/block.c +++ b/block.c @@ -1956,8 +1956,8 @@ static int multiwrite_merge(BlockDriverState *bs, BlockRequest *reqs, int64_t oldreq_last = reqs[outidx].sector + reqs[outidx].nb_sectors; // This handles the cases that are valid for all block drivers, namely - // exactly sequential writes and overlapping writes. - if (reqs[i].sector <= oldreq_last) { + // exactly sequential writes + if (reqs[i].sector == oldreq_last) { merge = 1; } -- 1.6.6.1