From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:49272) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RR2Cx-0002iQ-Hm for qemu-devel@nongnu.org; Thu, 17 Nov 2011 08:41:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RR2Cn-0000w6-F0 for qemu-devel@nongnu.org; Thu, 17 Nov 2011 08:40:51 -0500 Received: from mtagate3.uk.ibm.com ([194.196.100.163]:56626) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RR2Cn-0000vT-7A 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 mtagate3.uk.ibm.com (8.13.1/8.13.1) with ESMTP id pAHDedmi015334 for ; Thu, 17 Nov 2011 13:40:39 GMT Received: from d06av03.portsmouth.uk.ibm.com (d06av03.portsmouth.uk.ibm.com [9.149.37.213]) by d06nrmr1707.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id pAHDedBl1691818 for ; Thu, 17 Nov 2011 13:40:39 GMT Received: from d06av03.portsmouth.uk.ibm.com (localhost.localdomain [127.0.0.1]) by d06av03.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id pAHDeci3020023 for ; Thu, 17 Nov 2011 06:40:38 -0700 From: Stefan Hajnoczi Date: Thu, 17 Nov 2011 13:40:29 +0000 Message-Id: <1321537232-799-6-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 5/8] block: wait for overlapping requests 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 When copy-on-read is enabled it is necessary to wait for overlapping requests before issuing new requests. This prevents races between the copy-on-read and a write request. Signed-off-by: Stefan Hajnoczi --- block.c | 35 +++++++++++++++++++++++++++++++++++ 1 files changed, 35 insertions(+), 0 deletions(-) diff --git a/block.c b/block.c index c90880b..da7aaa2 100644 --- a/block.c +++ b/block.c @@ -1099,6 +1099,7 @@ struct BdrvTrackedRequest { int nb_sectors; bool is_write; QLIST_ENTRY(BdrvTrackedRequest) list; + CoQueue wait_queue; /* coroutines blocked on this request */ }; /** @@ -1109,6 +1110,7 @@ struct BdrvTrackedRequest { static void tracked_request_end(BdrvTrackedRequest *req) { QLIST_REMOVE(req, list); + qemu_co_queue_restart_all(&req->wait_queue); } /** @@ -1126,9 +1128,34 @@ static void tracked_request_begin(BdrvTrackedRequest *req, .is_write = is_write, }; + qemu_co_queue_init(&req->wait_queue); + QLIST_INSERT_HEAD(&bs->tracked_requests, req, list); } +static bool tracked_request_overlaps(BdrvTrackedRequest *req, + int64_t sector_num, int nb_sectors) { + return false; /* not yet implemented */ +} + +static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs, + int64_t sector_num, int nb_sectors) +{ + BdrvTrackedRequest *req; + bool retry; + + do { + retry = false; + QLIST_FOREACH(req, &bs->tracked_requests, list) { + if (tracked_request_overlaps(req, sector_num, nb_sectors)) { + qemu_co_queue_wait(&req->wait_queue); + retry = true; + break; + } + } + } while (retry); +} + /* * Return values: * 0 - success @@ -1423,6 +1450,10 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, bdrv_io_limits_intercept(bs, false, nb_sectors); } + if (bs->copy_on_read) { + wait_for_overlapping_requests(bs, sector_num, nb_sectors); + } + tracked_request_begin(&req, bs, sector_num, nb_sectors, false); ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov); tracked_request_end(&req); @@ -1462,6 +1493,10 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, bdrv_io_limits_intercept(bs, true, nb_sectors); } + if (bs->copy_on_read) { + wait_for_overlapping_requests(bs, sector_num, nb_sectors); + } + tracked_request_begin(&req, bs, sector_num, nb_sectors, true); ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov); -- 1.7.7.1