From patchwork Wed Mar 18 08:53:09 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kiyoshi Ueda X-Patchwork-Id: 12787 X-Patchwork-Delegate: agk@redhat.com 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 n2I8rZ35023627 for ; Wed, 18 Mar 2009 08:53:35 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 9F76E618C29; Wed, 18 Mar 2009 04:53:35 -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 n2I8rXH9005436 for ; Wed, 18 Mar 2009 04:53:34 -0400 Received: from mx1.redhat.com (mx1.redhat.com [172.16.48.31]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n2I8rYcX023344; Wed, 18 Mar 2009 04:53:34 -0400 Received: from tyo202.gate.nec.co.jp (TYO202.gate.nec.co.jp [202.32.8.206]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n2I8rJ91001917; Wed, 18 Mar 2009 04:53:19 -0400 Received: from mailgate3.nec.co.jp ([10.7.69.195]) by tyo202.gate.nec.co.jp (8.13.8/8.13.4) with ESMTP id n2I8rAnq020657; Wed, 18 Mar 2009 17:53:10 +0900 (JST) Received: (from root@localhost) by mailgate3.nec.co.jp (8.11.7/3.7W-MAILGATE-NEC) id n2I8r9609284; Wed, 18 Mar 2009 17:53:09 +0900 (JST) Received: from mailsv.linux.bs1.fc.nec.co.jp (mailsv.linux.bs1.fc.nec.co.jp [10.34.125.2]) by mailsv.nec.co.jp (8.13.8/8.13.4) with ESMTP id n2I8r9J2029834; Wed, 18 Mar 2009 17:53:09 +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 2168EE48276; Wed, 18 Mar 2009 17:53:09 +0900 (JST) Message-ID: <49C0B675.6000905@ct.jp.nec.com> Date: Wed, 18 Mar 2009 17:53:09 +0900 From: Kiyoshi Ueda User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Alasdair Kergon References: <49C0B474.4000204@ct.jp.nec.com> In-Reply-To: <49C0B474.4000204@ct.jp.nec.com> X-RedHat-Spam-Score: -0.25 X-Scanned-By: MIMEDefang 2.58 on 172.16.52.254 X-Scanned-By: MIMEDefang 2.63 on 172.16.48.31 X-loop: dm-devel@redhat.com Cc: Christof Schmitt , device-mapper development Subject: [dm-devel] [PATCH 3/8] 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: 2.6.29-rc8/drivers/md/dm.c =================================================================== --- 2.6.29-rc8.orig/drivers/md/dm.c +++ 2.6.29-rc8/drivers/md/dm.c @@ -1492,6 +1492,30 @@ 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: