From patchwork Fri May 15 03:10:17 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chandra Seetharaman X-Patchwork-Id: 23946 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 n4F3A158029076 for ; Fri, 15 May 2009 03:10:01 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 7103B618877; Thu, 14 May 2009 23:10:00 -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 n4F39ws9018207 for ; Thu, 14 May 2009 23:09:58 -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 n4F39vR1019412; Thu, 14 May 2009 23:09:57 -0400 Received: from e38.co.us.ibm.com (e38.co.us.ibm.com [32.97.110.159]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n4F39foE006708; Thu, 14 May 2009 23:09:41 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e38.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n4F36xqI004944; Thu, 14 May 2009 21:06:59 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n4F39f1m190938; Thu, 14 May 2009 21:09:41 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n4F39fM1030113; Thu, 14 May 2009 21:09:41 -0600 Received: from [9.47.17.98] (chandra-ubuntu.beaverton.ibm.com [9.47.17.98]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id n4F39eu1030013; Thu, 14 May 2009 21:09:40 -0600 From: Chandra Seetharaman To: dm-devel In-Reply-To: <1241493497.8721.60.camel@chandra-ubuntu> References: <1241493497.8721.60.camel@chandra-ubuntu> Organization: IBM Date: Thu, 14 May 2009 20:10:17 -0700 Message-Id: <1242357018.15931.14.camel@chandra-ubuntu> Mime-Version: 1.0 X-RedHat-Spam-Score: -3.5 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: Nikanth Karthikesan , Mike Christie Subject: [dm-devel] Re: [PATCH] dm mpath: delay retry activate_path on SCSI_DH_RETRY X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.5 Precedence: junk Reply-To: sekharan@linux.vnet.ibm.com, 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 Resubmitting the patch with 2 changes: 1. pg_init_delay_secs was used inconsistently (jiffies and seconds). Fixed the problem 2. Moved the #define to dm_mpath.c from scsi_dh.h ----------------------- From: Chandra Seetharaman SCSI Device Handlers return SCSI_DH_IMM_RETRY if we could retry immediately and SCSI_DH_RETRY in cases where it is better to retry after some delay. Currently we retry immediately irrespective of SCSI_DH_IMM_RETRY and SCSI_DH_RETRY. This patch adds a user configurable attribute pg_init_delay_secs which specifies the number of seconds to delay before retrying scsi_dh_activate, when it returned SCSI_DH_RETRY. Default for this attribute is set to 2 seconds. Signed-off-by: Nikanth Karthikesan Signed-off-by: Chandra Seetharaman --- drivers/md/dm-mpath.c | 44 +++++++++++++++++++++++++++++++++++--------- 1 file changed, 35 insertions(+), 9 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel Index: linux-2.6.29/drivers/md/dm-mpath.c =================================================================== --- linux-2.6.29.orig/drivers/md/dm-mpath.c +++ linux-2.6.29/drivers/md/dm-mpath.c @@ -24,6 +24,7 @@ #define DM_MSG_PREFIX "multipath" #define MESG_STR(x) x, sizeof(x) +#define DM_PG_INIT_RETRY_DELAY 2 /* Path properties */ struct pgpath { @@ -35,7 +36,7 @@ struct pgpath { struct dm_path path; struct work_struct deactivate_path; - struct work_struct activate_path; + struct delayed_work activate_path; }; #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path) @@ -69,6 +70,7 @@ struct multipath { struct list_head priority_groups; unsigned pg_init_required; /* pg_init needs calling? */ unsigned pg_init_in_progress; /* Only one pg_init allowed at once */ + unsigned pg_init_delay; /* To delay or not to delay */ unsigned nr_valid_paths; /* Total number of usable paths */ struct pgpath *current_pgpath; @@ -81,6 +83,7 @@ struct multipath { unsigned saved_queue_if_no_path;/* Saved state during suspension */ unsigned pg_init_retries; /* Number of times to retry pg_init */ unsigned pg_init_count; /* Number of times pg_init called */ + unsigned pg_init_delay_secs; /* Delay in seconds before retry */ struct work_struct process_queued_ios; struct bio_list queued_ios; @@ -127,7 +130,7 @@ static struct pgpath *alloc_pgpath(void) if (pgpath) { pgpath->is_active = 1; INIT_WORK(&pgpath->deactivate_path, deactivate_path); - INIT_WORK(&pgpath->activate_path, activate_path); + INIT_DELAYED_WORK(&pgpath->activate_path, activate_path); } return pgpath; @@ -195,6 +198,7 @@ static struct multipath *alloc_multipath INIT_LIST_HEAD(&m->priority_groups); spin_lock_init(&m->lock); m->queue_io = 1; + m->pg_init_delay_secs = DM_PG_INIT_RETRY_DELAY; INIT_WORK(&m->process_queued_ios, process_queued_ios); INIT_WORK(&m->trigger_event, trigger_event); m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache); @@ -443,9 +447,12 @@ static void process_queued_ios(struct wo m->pg_init_count++; m->pg_init_required = 0; list_for_each_entry(tmp, &pgpath->pg->pgpaths, list) { - queue_work(kmpath_handlerd, &tmp->activate_path); + queue_delayed_work(kmpath_handlerd, &tmp->activate_path, + m->pg_init_delay ? + m->pg_init_delay_secs * HZ : 0); m->pg_init_in_progress++; } + m->pg_init_delay = 0; } out: spin_unlock_irqrestore(&m->lock, flags); @@ -714,8 +721,9 @@ static int parse_features(struct arg_set const char *param_name; static struct param _params[] = { - {0, 3, "invalid number of feature args"}, + {0, 5, "invalid number of feature args"}, {1, 50, "pg_init_retries must be between 1 and 50"}, + {1, 50, "pg_init_delay_secs must be between 1 and 50"}, }; r = read_param(_params, shift(as), &argc, &ti->error); @@ -742,6 +750,14 @@ static int parse_features(struct arg_set continue; } + if (!strnicmp(param_name, MESG_STR("pg_init_delay_secs")) && + (argc >= 1)) { + r = read_param(_params + 1, shift(as), + &m->pg_init_delay_secs, &ti->error); + argc--; + continue; + } + ti->error = "Unrecognised multipath feature request"; r = -EINVAL; } while (argc && !r); @@ -919,7 +935,7 @@ static int reinstate_path(struct pgpath queue_work(kmultipathd, &m->process_queued_ios); } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) { m->pg_init_in_progress++; - queue_work(kmpath_handlerd, &pgpath->activate_path); + queue_delayed_work(kmpath_handlerd, &pgpath->activate_path, 0); } dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti, @@ -1053,6 +1069,7 @@ static void pg_init_done(struct dm_path struct priority_group *pg = pgpath->pg; struct multipath *m = pg->m; unsigned long flags; + unsigned int delay = 0; /* device or driver problems */ switch (errors) { @@ -1077,8 +1094,11 @@ static void pg_init_done(struct dm_path */ bypass_pg(m, pg, 1); break; - /* TODO: For SCSI_DH_RETRY we should wait a couple seconds */ + /* + * For SCSI_DH_RETRY we wait before retrying. + */ case SCSI_DH_RETRY: + delay = 1; case SCSI_DH_IMM_RETRY: case SCSI_DH_RES_TEMP_UNAVAIL: if (pg_init_limit_reached(m, pgpath)) @@ -1107,8 +1127,10 @@ static void pg_init_done(struct dm_path } m->pg_init_in_progress--; - if (!m->pg_init_in_progress) + if (!m->pg_init_in_progress) { + m->pg_init_delay = delay; queue_work(kmultipathd, &m->process_queued_ios); + } spin_unlock_irqrestore(&m->lock, flags); } @@ -1116,7 +1138,7 @@ static void activate_path(struct work_st { int ret; struct pgpath *pgpath = - container_of(work, struct pgpath, activate_path); + container_of(work, struct pgpath, activate_path.work); ret = scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev)); pg_init_done(&pgpath->path, ret); @@ -1252,11 +1274,15 @@ static int multipath_status(struct dm_ta DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count); else { DMEMIT("%u ", m->queue_if_no_path + - (m->pg_init_retries > 0) * 2); + (m->pg_init_retries > 0) * 2 + + (m->pg_init_delay_secs != + DM_PG_INIT_RETRY_DELAY) * 2); if (m->queue_if_no_path) DMEMIT("queue_if_no_path "); if (m->pg_init_retries) DMEMIT("pg_init_retries %u ", m->pg_init_retries); + if (m->pg_init_delay_secs != DM_PG_INIT_RETRY_DELAY) + DMEMIT("pg_init_delay_secs %u ", m->pg_init_delay_secs); } if (!m->hw_handler_name || type == STATUSTYPE_INFO)