No functional change. Repost with changes made to apply cleanly on top of the patch (http://marc.info/?l=dm-devel&m=124424663327710&w=2) that changed dm-mpath.c ----------------- From: Chandra Seetharaman <sekharan@xxxxxxxxxx> 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 <knikanth@xxxxxxx> Signed-off-by: Chandra Seetharaman <sekharan@xxxxxxxxxx> -- --- drivers/md/dm-mpath.c | 43 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 34 insertions(+), 9 deletions(-) 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); @@ -443,7 +447,9 @@ 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) { - if (queue_work(kmpath_handlerd, &tmp->activate_path)) + if (queue_delayed_work(kmpath_handlerd, + &tmp->activate_path, m->pg_init_delay ? + m->pg_init_delay_secs * HZ : 0)) m->pg_init_in_progress++; } } @@ -714,8 +720,9 @@ 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 +749,14 @@ 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); @@ -918,7 +933,7 @@ static int reinstate_path(struct pgpath m->current_pgpath = NULL; queue_work(kmultipathd, &m->process_queued_ios); } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) { - if (queue_work(kmpath_handlerd, &pgpath->activate_path)) + if (queue_work(kmpath_handlerd, &pgpath->activate_path.work)) m->pg_init_in_progress++; } @@ -1053,6 +1068,7 @@ 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 +1093,11 @@ 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 +1126,10 @@ 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 +1137,7 @@ 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 +1273,15 @@ 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) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
