From patchwork Fri Apr 24 08:15:12 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kiyoshi Ueda X-Patchwork-Id: 19863 Received: from hormel.redhat.com (hormel1.redhat.com [209.132.177.33]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n3OIkhRG032581 for ; Fri, 24 Apr 2009 18:46:45 GMT Received: from listman.util.phx.redhat.com (listman.util.phx.redhat.com [10.8.4.110]) by hormel.redhat.com (Postfix) with ESMTP id EFAD661AD15; Fri, 24 Apr 2009 04:15:20 -0400 (EDT) Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by listman.util.phx.redhat.com (8.13.1/8.13.1) with ESMTP id n3O8FJXp025298 for ; Fri, 24 Apr 2009 04:15:19 -0400 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n3O8FJbn001699; Fri, 24 Apr 2009 04:15:19 -0400 Received: from tyo201.gate.nec.co.jp (TYO201.gate.nec.co.jp [202.32.8.193]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id n3O8FDv8018874; Fri, 24 Apr 2009 04:15:14 -0400 Received: from mailgate3.nec.co.jp ([10.7.69.195]) by tyo201.gate.nec.co.jp (8.13.8/8.13.4) with ESMTP id n3O8FD3h024317; Fri, 24 Apr 2009 17:15:13 +0900 (JST) Received: (from root@localhost) by mailgate3.nec.co.jp (8.11.7/3.7W-MAILGATE-NEC) id n3O8FDY01248; Fri, 24 Apr 2009 17:15:13 +0900 (JST) Received: from mailsv.linux.bs1.fc.nec.co.jp (mailsv.linux.bs1.fc.nec.co.jp [10.34.125.2]) by mailsv3.nec.co.jp (8.13.8/8.13.4) with ESMTP id n3O8FCYe026816; Fri, 24 Apr 2009 17:15:12 +0900 (JST) Received: from elcondor.linux.bs1.fc.nec.co.jp (elcondor.linux.bs1.fc.nec.co.jp [10.34.125.195]) by mailsv.linux.bs1.fc.nec.co.jp (Postfix) with ESMTP id A855EE482A3; Fri, 24 Apr 2009 17:15:12 +0900 (JST) Message-ID: <49F17510.7010805@ct.jp.nec.com> Date: Fri, 24 Apr 2009 17:15:12 +0900 From: Kiyoshi Ueda User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Alasdair Kergon References: <49F17409.4060201@ct.jp.nec.com> In-Reply-To: <49F17409.4060201@ct.jp.nec.com> X-RedHat-Spam-Score: -0.059 X-Scanned-By: MIMEDefang 2.58 on 172.16.52.254 X-Scanned-By: MIMEDefang 2.63 on 172.16.48.32 X-loop: dm-devel@redhat.com Cc: device-mapper development Subject: [dm-devel] [PATCH 5/7] dm core: reject I/O violating new queue limits X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.5 Precedence: junk Reply-To: device-mapper development List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com This patch detects requests violating the queue limitations and rejects them. The same limitation checks are done when requests are submitted to the queue by blk_insert_cloned_request(). However, such violation can happen if a table is swapped and the queue limitations are shrunk while some requests are in the queue. Since struct request is a reliable one in the block layer and device drivers, dispatching such requests is pretty dangerous. (e.g. it may cause kernel panic easily.) So avoid to dispatch such problematic requests in request-based dm. Signed-off-by: Kiyoshi Ueda Signed-off-by: Jun'ichi Nomura Cc: Alasdair G Kergon --- drivers/md/dm.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel Index: 2.6.30-rc3/drivers/md/dm.c =================================================================== --- 2.6.30-rc3.orig/drivers/md/dm.c +++ 2.6.30-rc3/drivers/md/dm.c @@ -1500,6 +1500,30 @@ static void map_request(struct dm_target dm_get(md); tio->ti = ti; + + /* + * Although submitted requests to the md->queue are checked against + * the table/queue limitations at the submission time, the limitations + * may be changed by a table swapping while those already checked + * requests are in the md->queue. + * If the limitations have been shrunk in such situations, we may be + * dispatching requests violating the current limitations here. + * Since struct request is a reliable one in the block-layer + * and device drivers, dispatching such requests is dangerous. + * (e.g. it may cause kernel panic easily.) + * Avoid to dispatch such problematic requests in request-based dm. + * + * Since dm_kill_unmapped_request() expects that tio->ti is correctly + * set, this has to be done after the set. + */ + r = blk_rq_check_limits(rq->q, rq); + if (unlikely(r)) { + DMWARN("violating the queue limitation. the limitation may be" + " shrunk while there are some requests in the queue."); + dm_kill_unmapped_request(clone, r); + return; + } + r = ti->type->map_rq(ti, clone, &tio->info); switch (r) { case DM_MAPIO_SUBMITTED: