dm mpath: Add timeout mechanism for queue_if_no_path

Message ID	20200102224512.3605010-1-krisman@collabora.com (mailing list archive)
State	Changes Requested, archived
Delegated to:	Mike Snitzer
Headers	show Return-Path: <SRS0=x/ds=2Y=redhat.com=dm-devel-bounces@kernel.org> DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 875E4206DB sender: krisman) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id C357C28AE2A; Thu, 2 Jan 2020 22:45:17 +0000 (GMT) From: Gabriel Krisman Bertazi <krisman@collabora.com> To: agk@redhat.com Date: Thu, 2 Jan 2020 17:45:12 -0500 Message-Id: <20200102224512.3605010-1-krisman@collabora.com> MIME-Version: 1.0 Cc: snitzer@redhat.com, Bharath Ravi <rbharath@google.com>, Khazhismel Kumykov <khazhy@google.com>, dm-devel@redhat.com, Anatol Pomazau <anatol@google.com>, Gabriel Krisman Bertazi <krisman@collabora.com>, kernel@collabora.com, Frank Mayhar <fmayhar@google.com> Subject: [dm-devel] [PATCH] dm mpath: Add timeout mechanism for queue_if_no_path Precedence: junk Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit
Series	dm mpath: Add timeout mechanism for queue_if_no_path \| expand dm mpath: Add timeout mechanism for queue_if_no_path

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index e0c32793c248..72ba7ae98458 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -91,6 +91,9 @@ struct multipath { struct work_struct process_queued_bios; struct bio_list queued_bios; + + unsigned int nopath_timeout; /* Timeout for queue_if_no_path */ + struct timer_list nopath_timer; }; /* @@ -109,6 +112,11 @@ static void activate_or_offline_path(struct pgpath *pgpath); static void activate_path_work(struct work_struct *work); static void process_queued_bios(struct work_struct *work); +static void handle_nopath_timeout(struct timer_list *t); +static void enable_nopath_timeout(struct multipath *m); +static int activate_nopath_timeout(struct multipath *m, + unsigned int to, int enable); + /*----------------------------------------------- * Multipath state flags. *-----------------------------------------------*/ @@ -195,6 +203,8 @@ static struct multipath *alloc_multipath(struct dm_target *ti) m->ti = ti; ti->private = m; + + timer_setup(&m->nopath_timer, handle_nopath_timeout, 0); } return m; @@ -1016,6 +1026,7 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m) {0, 8, "invalid number of feature args"}, {1, 50, "pg_init_retries must be between 1 and 50"}, {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"}, + {0, 600, "queue_if_no_path_timeout must be 0 or a timeout in seconds"}, }; r = dm_read_arg_group(_args, as, &argc, &ti->error); @@ -1070,6 +1081,16 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m) continue; } + if (!strcasecmp(arg_name, "queue_if_no_path_timeout") && + (argc >= 1)) { + unsigned int to; + + r = dm_read_arg(_args+3, as, &to, &ti->error); + activate_nopath_timeout(m, to, 0); + argc--; + continue; + } + ti->error = "Unrecognised multipath feature request"; r = -EINVAL; } while (argc && !r); @@ -1090,6 +1111,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv) struct dm_arg_set as; unsigned pg_count = 0; unsigned next_pg_num; + unsigned long flags; as.argc = argc; as.argv = argv; @@ -1154,6 +1176,10 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv) goto bad; } + spin_lock_irqsave(&m->lock, flags); + enable_nopath_timeout(m); + spin_unlock_irqrestore(&m->lock, flags); + ti->num_flush_bios = 1; ti->num_discard_bios = 1; ti->num_write_same_bios = 1; @@ -1208,10 +1234,26 @@ static void multipath_dtr(struct dm_target *ti) { struct multipath *m = ti->private; + del_timer_sync(&m->nopath_timer); + flush_multipath_work(m); free_multipath(m); } +/* + * If the queue_if_no_path timeout fires, turn off queue_if_no_path and + * process any queued I/O. + */ +static void handle_nopath_timeout(struct timer_list *t) +{ + struct multipath *m = from_timer(m, t, nopath_timer); + struct mapped_device *md = dm_table_get_md((m)->ti->table); + + DMWARN("queue_if_no_path timeout on %s", dm_device_name(md)); + + (void)queue_if_no_path(m, false, false); +} + /* * Take a path out of use. */ @@ -1241,6 +1283,8 @@ static int fail_path(struct pgpath *pgpath) schedule_work(&m->trigger_event); + enable_nopath_timeout(m); + out: spin_unlock_irqrestore(&m->lock, flags); @@ -1291,6 +1335,8 @@ static int reinstate_path(struct pgpath *pgpath) process_queued_io_list(m); } + del_timer_sync(&m->nopath_timer); + return r; } @@ -1314,6 +1360,47 @@ static int action_dev(struct multipath *m, struct dm_dev *dev, return r; } +/* + * Enable the queue_if_no_path timeout if necessary. Called with m->lock + * held. + */ +static void enable_nopath_timeout(struct multipath *m) +{ + if (atomic_read(&m->nr_valid_paths) == 0 && m->nopath_timeout > 0 && + test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) { + mod_timer(&m->nopath_timer, jiffies + m->nopath_timeout * HZ); + } +} + +static int activate_nopath_timeout(struct multipath *m, unsigned int to, + int enable) +{ + unsigned long flags; + + spin_lock_irqsave(&m->lock, flags); + + m->nopath_timeout = to; + if (to && enable) + enable_nopath_timeout(m); + + spin_unlock_irqrestore(&m->lock, flags); + + if (!to) + del_timer_sync(&m->nopath_timer); + return 0; +} + +static int set_nopath_timeout(struct multipath *m, const char *timestr) +{ + unsigned long to; + + if (!timestr || (kstrtol(timestr, 10, &to) != 1)) { + DMWARN("invalid timeout supplied to %s", __func__); + return -EINVAL; + } + return activate_nopath_timeout(m, to, 1); +} + /* * Temporarily try to avoid having to use the specified PG */ @@ -1682,7 +1769,8 @@ static void multipath_status(struct dm_target *ti, status_type_t type, (m->pg_init_retries > 0) * 2 + (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 + test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) + - (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2); + (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2 + + (m->nopath_timeout > 0) * 2); if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) DMEMIT("queue_if_no_path "); @@ -1702,6 +1790,9 @@ static void multipath_status(struct dm_target *ti, status_type_t type, break; } } + if (m->nopath_timeout) + DMEMIT("queue_if_no_path_timeout %u ", + m->nopath_timeout); } if (!m->hw_handler_name || type == STATUSTYPE_INFO) @@ -1821,6 +1912,9 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv, } else if (!strcasecmp(argv[0], "switch_group")) { r = switch_pg_num(m, argv[1]); goto out; + } else if (!strcasecmp(argv[0], "queue_if_no_path_timeout")) { + r = set_nopath_timeout(m, argv[1]); + goto out; } else if (!strcasecmp(argv[0], "reinstate_path")) action = reinstate_path; else if (!strcasecmp(argv[0], "fail_path"))

dm mpath: Add timeout mechanism for queue_if_no_path

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