From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:49179) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RR2Cs-0002Zm-6q for qemu-devel@nongnu.org; Thu, 17 Nov 2011 08:40:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RR2Cn-0000wF-IK for qemu-devel@nongnu.org; Thu, 17 Nov 2011 08:40:45 -0500 Received: from mtagate1.uk.ibm.com ([194.196.100.161]:52807) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RR2Cn-0000vX-Ap for qemu-devel@nongnu.org; Thu, 17 Nov 2011 08:40:41 -0500 Received: from d06nrmr1707.portsmouth.uk.ibm.com (d06nrmr1707.portsmouth.uk.ibm.com [9.149.39.225]) by mtagate1.uk.ibm.com (8.13.1/8.13.1) with ESMTP id pAHDedM9013175 for ; Thu, 17 Nov 2011 13:40:39 GMT Received: from d06av04.portsmouth.uk.ibm.com (d06av04.portsmouth.uk.ibm.com [9.149.37.216]) by d06nrmr1707.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id pAHDedg72253002 for ; Thu, 17 Nov 2011 13:40:39 GMT Received: from d06av04.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av04.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id pAHDecwb012019 for ; Thu, 17 Nov 2011 06:40:39 -0700 From: Stefan Hajnoczi Date: Thu, 17 Nov 2011 13:40:30 +0000 Message-Id: <1321537232-799-7-git-send-email-stefanha@linux.vnet.ibm.com> In-Reply-To: <1321537232-799-1-git-send-email-stefanha@linux.vnet.ibm.com> References: <1321537232-799-1-git-send-email-stefanha@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH v2 6/8] block: request overlap detection List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Paolo Bonzini , Marcelo Tosatti , Stefan Hajnoczi Detect overlapping requests and remember to align to cluster boundaries if the image format uses them. This assumes that allocating I/O is performed in cluster granularity - which is true for qcow2, qed, etc. Signed-off-by: Stefan Hajnoczi --- block.c | 40 ++++++++++++++++++++++++++++++++++++++-- 1 files changed, 38 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index da7aaa2..0eef122 100644 --- a/block.c +++ b/block.c @@ -1133,21 +1133,57 @@ static void tracked_request_begin(BdrvTrackedRequest *req, QLIST_INSERT_HEAD(&bs->tracked_requests, req, list); } +/** + * Round a region to cluster boundaries + */ +static void round_to_clusters(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, + int64_t *cluster_sector_num, + int *cluster_nb_sectors) +{ + BlockDriverInfo bdi; + + if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) { + *cluster_sector_num = sector_num; + *cluster_nb_sectors = nb_sectors; + } else { + int64_t c = bdi.cluster_size / BDRV_SECTOR_SIZE; + *cluster_sector_num = QEMU_ALIGN_DOWN(sector_num, c); + *cluster_nb_sectors = QEMU_ALIGN_UP(sector_num - *cluster_sector_num + + nb_sectors, c); + } +} + static bool tracked_request_overlaps(BdrvTrackedRequest *req, int64_t sector_num, int nb_sectors) { - return false; /* not yet implemented */ + /* aaaa bbbb */ + if (sector_num >= req->sector_num + req->nb_sectors) { + return false; + } + /* bbbb aaaa */ + if (req->sector_num >= sector_num + nb_sectors) { + return false; + } + return true; } static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs, int64_t sector_num, int nb_sectors) { BdrvTrackedRequest *req; + int64_t cluster_sector_num; + int cluster_nb_sectors; bool retry; + /* If we touch the same cluster it counts as an overlap */ + round_to_clusters(bs, sector_num, nb_sectors, + &cluster_sector_num, &cluster_nb_sectors); + do { retry = false; QLIST_FOREACH(req, &bs->tracked_requests, list) { - if (tracked_request_overlaps(req, sector_num, nb_sectors)) { + if (tracked_request_overlaps(req, cluster_sector_num, + cluster_nb_sectors)) { qemu_co_queue_wait(&req->wait_queue); retry = true; break; -- 1.7.7.1