/* * Copyright (C) 2003 Sistina Software Limited. * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved. * * This file is released under the GPL. */ #include <linux/device-mapper.h> #include "dm-path-selector.h" #include "dm-uevent.h" #include <linux/ctype.h> #include <linux/init.h> #include <linux/mempool.h> #include <linux/module.h> #include <linux/pagemap.h> #include <linux/slab.h> #include <linux/time.h> #include <linux/workqueue.h> #include <linux/delay.h> #include <scsi/scsi_dh.h> #include <linux/atomic.h> #define DM_MSG_PREFIX "multipath" #define DM_PG_INIT_DELAY_MSECS 2000 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1) /* Path properties */ struct pgpath { struct list_head list; struct priority_group *pg; /* Owning PG */ unsigned is_active; /* Path status */ unsigned fail_count; /* Cumulative failure count */ struct dm_path path; struct delayed_work activate_path; }; #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path) /* * Paths are grouped into Priority Groups and numbered from 1 upwards. * Each has a path selector which controls which path gets used. */ struct priority_group { struct list_head list; struct multipath *m; /* Owning multipath instance */ struct path_selector ps; unsigned pg_num; /* Reference number */ unsigned bypassed; /* Temporarily bypass this PG? */ unsigned nr_pgpaths; /* Number of paths in PG */ struct list_head pgpaths; }; /* Multipath context */ struct multipath { struct list_head list; struct dm_target *ti; const char *hw_handler_name; char *hw_handler_params; spinlock_t lock; unsigned nr_priority_groups; struct list_head priority_groups; wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */ unsigned pg_init_required; /* pg_init needs calling? */ unsigned pg_init_in_progress; /* Only one pg_init allowed at once */ unsigned pg_init_delay_retry; /* Delay pg_init retry? */ unsigned nr_valid_paths; /* Total number of usable paths */ struct pgpath *current_pgpath; struct priority_group *current_pg; struct priority_group *next_pg; /* Switch to this PG if set */ unsigned repeat_count; /* I/Os left before calling PS again */ unsigned queue_io:1; /* Must we queue all I/O? */ unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */ unsigned saved_queue_if_no_path:1; /* Saved state during suspension */ unsigned retain_attached_hw_handler:1; /* If there's already a hw_handler present, don't change it. */ 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_msecs; /* Number of msecs before pg_init retry */ unsigned queue_size; struct work_struct process_queued_ios; struct list_head queued_ios; struct work_struct trigger_event; /* * We must use a mempool of dm_mpath_io structs so that we * can resubmit bios on error. */ mempool_t *mpio_pool; struct mutex work_mutex; }; /* * Context information attached to each bio we process. */ struct dm_mpath_io { struct pgpath *pgpath; size_t nr_bytes; }; typedef int (*action_fn) (struct pgpath *pgpath); #define MIN_IOS 256 /* Mempool size */ static struct kmem_cache *_mpio_cache; static struct workqueue_struct *kmultipathd, *kmpath_handlerd; static void process_queued_ios(struct work_struct *work); static void trigger_event(struct work_struct *work); static void activate_path(struct work_struct *work); /*----------------------------------------------- * Allocation routines *-----------------------------------------------*/ static struct pgpath *alloc_pgpath(void) { struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL); if (pgpath) { pgpath->is_active = 1; INIT_DELAYED_WORK(&pgpath->activate_path, activate_path); } return pgpath; } static void free_pgpath(struct pgpath *pgpath) { kfree(pgpath); } static struct priority_group *alloc_priority_group(void) { struct priority_group *pg; pg = kzalloc(sizeof(*pg), GFP_KERNEL); if (pg) INIT_LIST_HEAD(&pg->pgpaths); return pg; } static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti) { struct pgpath *pgpath, *tmp; struct multipath *m = ti->private; list_for_each_entry_safe(pgpath, tmp, pgpaths, list) { list_del(&pgpath->list); if (m->hw_handler_name) scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev)); dm_put_device(ti, pgpath->path.dev); free_pgpath(pgpath); } } static void free_priority_group(struct priority_group *pg, struct dm_target *ti) { struct path_selector *ps = &pg->ps; if (ps->type) { ps->type->destroy(ps); dm_put_path_selector(ps->type); } free_pgpaths(&pg->pgpaths, ti); kfree(pg); } static struct multipath *alloc_multipath(struct dm_target *ti) { struct multipath *m; m = kzalloc(sizeof(*m), GFP_KERNEL); if (m) { INIT_LIST_HEAD(&m->priority_groups); INIT_LIST_HEAD(&m->queued_ios); spin_lock_init(&m->lock); m->queue_io = 1; m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT; INIT_WORK(&m->process_queued_ios, process_queued_ios); INIT_WORK(&m->trigger_event, trigger_event); init_waitqueue_head(&m->pg_init_wait); mutex_init(&m->work_mutex); m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache); if (!m->mpio_pool) { kfree(m); return NULL; } m->ti = ti; ti->private = m; } return m; } static void free_multipath(struct multipath *m) { struct priority_group *pg, *tmp; list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) { list_del(&pg->list); free_priority_group(pg, m->ti); } kfree(m->hw_handler_name); kfree(m->hw_handler_params); mempool_destroy(m->mpio_pool); kfree(m); } static int set_mapinfo(struct multipath *m, union map_info *info) { struct dm_mpath_io *mpio; mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC); if (!mpio) return -ENOMEM; memset(mpio, 0, sizeof(*mpio)); info->ptr = mpio; return 0; } static void clear_mapinfo(struct multipath *m, union map_info *info) { struct dm_mpath_io *mpio = info->ptr; info->ptr = NULL; mempool_free(mpio, m->mpio_pool); } /*----------------------------------------------- * Path selection *-----------------------------------------------*/ static void __pg_init_all_paths(struct multipath *m) { struct pgpath *pgpath; unsigned long pg_init_delay = 0; m->pg_init_count++; m->pg_init_required = 0; if (m->pg_init_delay_retry) pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ? m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS); list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) { /* Skip failed paths */ if (!pgpath->is_active) continue; if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path, pg_init_delay)) m->pg_init_in_progress++; } } static void __switch_pg(struct multipath *m, struct pgpath *pgpath) { m->current_pg = pgpath->pg; /* Must we initialise the PG first, and queue I/O till it's ready? */ if (m->hw_handler_name) { m->pg_init_required = 1; m->queue_io = 1; } else { m->pg_init_required = 0; m->queue_io = 0; } m->pg_init_count = 0; } static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg, size_t nr_bytes) { struct dm_path *path; path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes); if (!path) return -ENXIO; m->current_pgpath = path_to_pgpath(path); if (m->current_pg != pg) __switch_pg(m, m->current_pgpath); return 0; } static void __choose_pgpath(struct multipath *m, size_t nr_bytes) { struct priority_group *pg; unsigned bypassed = 1; if (!m->nr_valid_paths) goto failed; /* Were we instructed to switch PG? */ if (m->next_pg) { pg = m->next_pg; m->next_pg = NULL; if (!__choose_path_in_pg(m, pg, nr_bytes)) return; } /* Don't change PG until it has no remaining paths */ if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes)) return; /* * Loop through priority groups until we find a valid path. * First time we skip PGs marked 'bypassed'. * Second time we only try the ones we skipped, but set * pg_init_delay_retry so we do not hammer controllers. */ do { list_for_each_entry(pg, &m->priority_groups, list) { if (pg->bypassed == bypassed) continue; if (!__choose_path_in_pg(m, pg, nr_bytes)) { if (!bypassed) m->pg_init_delay_retry = 1; return; } } } while (bypassed--); failed: m->current_pgpath = NULL; m->current_pg = NULL; } /* * Check whether bios must be queued in the device-mapper core rather * than here in the target. * * m->lock must be held on entry. * * If m->queue_if_no_path and m->saved_queue_if_no_path hold the * same value then we are not between multipath_presuspend() * and multipath_resume() calls and we have no need to check * for the DMF_NOFLUSH_SUSPENDING flag. */ static int __must_push_back(struct multipath *m) { return (m->queue_if_no_path != m->saved_queue_if_no_path && dm_noflush_suspending(m->ti)); } static int map_io(struct multipath *m, struct request *clone, union map_info *map_context, unsigned was_queued) { int r = DM_MAPIO_REMAPPED; size_t nr_bytes = blk_rq_bytes(clone); unsigned long flags; struct pgpath *pgpath; struct block_device *bdev; struct dm_mpath_io *mpio = map_context->ptr; spin_lock_irqsave(&m->lock, flags); /* Do we need to select a new pgpath? */ if (!m->current_pgpath || (!m->queue_io && (m->repeat_count && --m->repeat_count == 0))) __choose_pgpath(m, nr_bytes); pgpath = m->current_pgpath; if (was_queued) m->queue_size--; if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path)) { /* Queue for the daemon to resubmit */ list_add_tail(&clone->queuelist, &m->queued_ios); m->queue_size++; if ((m->pg_init_required && !m->pg_init_in_progress) || !m->queue_io) queue_work(kmultipathd, &m->process_queued_ios); pgpath = NULL; r = DM_MAPIO_SUBMITTED; } else if (pgpath) { bdev = pgpath->path.dev->bdev; clone->q = bdev_get_queue(bdev); clone->rq_disk = bdev->bd_disk; } else if (__must_push_back(m)) r = DM_MAPIO_REQUEUE; else r = -EIO; /* Failed */ mpio->pgpath = pgpath; mpio->nr_bytes = nr_bytes; if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io) pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path, nr_bytes); spin_unlock_irqrestore(&m->lock, flags); return r; } /* * If we run out of usable paths, should we queue I/O or error it? */ static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, unsigned save_old_value) { unsigned long flags; spin_lock_irqsave(&m->lock, flags); if (save_old_value) m->saved_queue_if_no_path = m->queue_if_no_path; else m->saved_queue_if_no_path = queue_if_no_path; m->queue_if_no_path = queue_if_no_path; if (!m->queue_if_no_path && m->queue_size) queue_work(kmultipathd, &m->process_queued_ios); spin_unlock_irqrestore(&m->lock, flags); return 0; } /*----------------------------------------------------------------- * The multipath daemon is responsible for resubmitting queued ios. *---------------------------------------------------------------*/ static void dispatch_queued_ios(struct multipath *m) { int r; unsigned long flags; union map_info *info; struct request *clone, *n; LIST_HEAD(cl); spin_lock_irqsave(&m->lock, flags); list_splice_init(&m->queued_ios, &cl); spin_unlock_irqrestore(&m->lock, flags); list_for_each_entry_safe(clone, n, &cl, queuelist) { list_del_init(&clone->queuelist); info = dm_get_rq_mapinfo(clone); r = map_io(m, clone, info, 1); if (r < 0) { clear_mapinfo(m, info); dm_kill_unmapped_request(clone, r); } else if (r == DM_MAPIO_REMAPPED) dm_dispatch_request(clone); else if (r == DM_MAPIO_REQUEUE) { clear_mapinfo(m, info); dm_requeue_unmapped_request(clone); } } } static void process_queued_ios(struct work_struct *work) { struct multipath *m = container_of(work, struct multipath, process_queued_ios); struct pgpath *pgpath = NULL; unsigned must_queue = 1; unsigned long flags; spin_lock_irqsave(&m->lock, flags); if (!m->current_pgpath) __choose_pgpath(m, 0); pgpath = m->current_pgpath; if ((pgpath && !m->queue_io) || (!pgpath && !m->queue_if_no_path)) must_queue = 0; if (m->pg_init_required && !m->pg_init_in_progress && pgpath) __pg_init_all_paths(m); spin_unlock_irqrestore(&m->lock, flags); if (!must_queue) dispatch_queued_ios(m); } /* * An event is triggered whenever a path is taken out of use. * Includes path failure and PG bypass. */ static void trigger_event(struct work_struct *work) { struct multipath *m = container_of(work, struct multipath, trigger_event); dm_table_event(m->ti->table); } /*----------------------------------------------------------------- * Constructor/argument parsing: * <#multipath feature args> [<arg>]* * <#hw_handler args> [hw_handler [<arg>]*] * <#priority groups> * <initial priority group> * [<selector> <#selector args> [<arg>]* * <#paths> <#per-path selector args> * [<path> [<arg>]* ]+ ]+ *---------------------------------------------------------------*/ static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg, struct dm_target *ti) { int r; struct path_selector_type *pst; unsigned ps_argc; static struct dm_arg _args[] = { {0, 1024, "invalid number of path selector args"}, }; pst = dm_get_path_selector(dm_shift_arg(as)); if (!pst) { ti->error = "unknown path selector type"; return -EINVAL; } r = dm_read_arg_group(_args, as, &ps_argc, &ti->error); if (r) { dm_put_path_selector(pst); return -EINVAL; } r = pst->create(&pg->ps, ps_argc, as->argv); if (r) { dm_put_path_selector(pst); ti->error = "path selector constructor failed"; return r; } pg->ps.type = pst; dm_consume_args(as, ps_argc); return 0; } static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps, struct dm_target *ti) { int r; struct pgpath *p; struct multipath *m = ti->private; struct request_queue *q = NULL; const char *attached_handler_name; /* we need at least a path arg */ if (as->argc < 1) { ti->error = "no device given"; return ERR_PTR(-EINVAL); } p = alloc_pgpath(); if (!p) return ERR_PTR(-ENOMEM); r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table), &p->path.dev); if (r) { ti->error = "error getting device"; goto bad; } if (m->retain_attached_hw_handler || m->hw_handler_name) q = bdev_get_queue(p->path.dev->bdev); if (m->retain_attached_hw_handler) { attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL); if (attached_handler_name) { /* * Reset hw_handler_name to match the attached handler * and clear any hw_handler_params associated with the * ignored handler. * * NB. This modifies the table line to show the actual * handler instead of the original table passed in. */ kfree(m->hw_handler_name); m->hw_handler_name = attached_handler_name; kfree(m->hw_handler_params); m->hw_handler_params = NULL; } } if (m->hw_handler_name) { /* * Increments scsi_dh reference, even when using an * already-attached handler. */ r = scsi_dh_attach(q, m->hw_handler_name); if (r == -EBUSY) { /* * Already attached to different hw_handler: * try to reattach with correct one. */ scsi_dh_detach(q); r = scsi_dh_attach(q, m->hw_handler_name); } if (r < 0) { ti->error = "error attaching hardware handler"; dm_put_device(ti, p->path.dev); goto bad; } if (m->hw_handler_params) { r = scsi_dh_set_params(q, m->hw_handler_params); if (r < 0) { ti->error = "unable to set hardware " "handler parameters"; scsi_dh_detach(q); dm_put_device(ti, p->path.dev); goto bad; } } } r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error); if (r) { dm_put_device(ti, p->path.dev); goto bad; } return p; bad: free_pgpath(p); return ERR_PTR(r); } static struct priority_group *parse_priority_group(struct dm_arg_set *as, struct multipath *m) { static struct dm_arg _args[] = { {1, 1024, "invalid number of paths"}, {0, 1024, "invalid number of selector args"} }; int r; unsigned i, nr_selector_args, nr_args; struct priority_group *pg; struct dm_target *ti = m->ti; if (as->argc < 2) { as->argc = 0; ti->error = "not enough priority group arguments"; return ERR_PTR(-EINVAL); } pg = alloc_priority_group(); if (!pg) { ti->error = "couldn't allocate priority group"; return ERR_PTR(-ENOMEM); } pg->m = m; r = parse_path_selector(as, pg, ti); if (r) goto bad; /* * read the paths */ r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error); if (r) goto bad; r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error); if (r) goto bad; nr_args = 1 + nr_selector_args; for (i = 0; i < pg->nr_pgpaths; i++) { struct pgpath *pgpath; struct dm_arg_set path_args; if (as->argc < nr_args) { ti->error = "not enough path parameters"; r = -EINVAL; goto bad; } path_args.argc = nr_args; path_args.argv = as->argv; pgpath = parse_path(&path_args, &pg->ps, ti); if (IS_ERR(pgpath)) { r = PTR_ERR(pgpath); goto bad; } pgpath->pg = pg; list_add_tail(&pgpath->list, &pg->pgpaths); dm_consume_args(as, nr_args); } return pg; bad: free_priority_group(pg, ti); return ERR_PTR(r); } static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m) { unsigned hw_argc; int ret; struct dm_target *ti = m->ti; static struct dm_arg _args[] = { {0, 1024, "invalid number of hardware handler args"}, }; if (dm_read_arg_group(_args, as, &hw_argc, &ti->error)) return -EINVAL; if (!hw_argc) return 0; m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL); if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name), "scsi_dh_%s", m->hw_handler_name)) { ti->error = "unknown hardware handler type"; ret = -EINVAL; goto fail; } if (hw_argc > 1) { char *p; int i, j, len = 4; for (i = 0; i <= hw_argc - 2; i++) len += strlen(as->argv[i]) + 1; p = m->hw_handler_params = kzalloc(len, GFP_KERNEL); if (!p) { ti->error = "memory allocation failed"; ret = -ENOMEM; goto fail; } j = sprintf(p, "%d", hw_argc - 1); for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1) j = sprintf(p, "%s", as->argv[i]); } dm_consume_args(as, hw_argc - 1); return 0; fail: kfree(m->hw_handler_name); m->hw_handler_name = NULL; return ret; } static int parse_features(struct dm_arg_set *as, struct multipath *m) { int r; unsigned argc; struct dm_target *ti = m->ti; const char *arg_name; static struct dm_arg _args[] = { {0, 6, "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"}, }; r = dm_read_arg_group(_args, as, &argc, &ti->error); if (r) return -EINVAL; if (!argc) return 0; do { arg_name = dm_shift_arg(as); argc--; if (!strcasecmp(arg_name, "queue_if_no_path")) { r = queue_if_no_path(m, 1, 0); continue; } if (!strcasecmp(arg_name, "retain_attached_hw_handler")) { m->retain_attached_hw_handler = 1; continue; } if (!strcasecmp(arg_name, "pg_init_retries") && (argc >= 1)) { r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error); argc--; continue; } if (!strcasecmp(arg_name, "pg_init_delay_msecs") && (argc >= 1)) { r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error); argc--; continue; } ti->error = "Unrecognised multipath feature request"; r = -EINVAL; } while (argc && !r); return r; } static int multipath_ctr(struct dm_target *ti, unsigned int argc, char **argv) { /* target arguments */ static struct dm_arg _args[] = { {0, 1024, "invalid number of priority groups"}, {0, 1024, "invalid initial priority group number"}, }; int r; struct multipath *m; struct dm_arg_set as; unsigned pg_count = 0; unsigned next_pg_num; as.argc = argc; as.argv = argv; m = alloc_multipath(ti); if (!m) { ti->error = "can't allocate multipath"; return -EINVAL; } r = parse_features(&as, m); if (r) goto bad; r = parse_hw_handler(&as, m); if (r) goto bad; r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error); if (r) goto bad; r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error); if (r) goto bad; if ((!m->nr_priority_groups && next_pg_num) || (m->nr_priority_groups && !next_pg_num)) { ti->error = "invalid initial priority group"; r = -EINVAL; goto bad; } /* parse the priority groups */ while (as.argc) { struct priority_group *pg; pg = parse_priority_group(&as, m); if (IS_ERR(pg)) { r = PTR_ERR(pg); goto bad; } m->nr_valid_paths += pg->nr_pgpaths; list_add_tail(&pg->list, &m->priority_groups); pg_count++; pg->pg_num = pg_count; if (!--next_pg_num) m->next_pg = pg; } if (pg_count != m->nr_priority_groups) { ti->error = "priority group count mismatch"; r = -EINVAL; goto bad; } ti->num_flush_requests = 1; ti->num_discard_requests = 1; return 0; bad: free_multipath(m); return r; } static void multipath_wait_for_pg_init_completion(struct multipath *m) { DECLARE_WAITQUEUE(wait, current); unsigned long flags; add_wait_queue(&m->pg_init_wait, &wait); while (1) { set_current_state(TASK_UNINTERRUPTIBLE); spin_lock_irqsave(&m->lock, flags); if (!m->pg_init_in_progress) { spin_unlock_irqrestore(&m->lock, flags); break; } spin_unlock_irqrestore(&m->lock, flags); io_schedule(); } set_current_state(TASK_RUNNING); remove_wait_queue(&m->pg_init_wait, &wait); } static void flush_multipath_work(struct multipath *m) { flush_workqueue(kmpath_handlerd); multipath_wait_for_pg_init_completion(m); flush_workqueue(kmultipathd); flush_work(&m->trigger_event); } static void multipath_dtr(struct dm_target *ti) { struct multipath *m = ti->private; flush_multipath_work(m); free_multipath(m); } /* * Map cloned requests */ static int multipath_map(struct dm_target *ti, struct request *clone, union map_info *map_context) { int r; struct multipath *m = (struct multipath *) ti->private; if (set_mapinfo(m, map_context) < 0) /* ENOMEM, requeue */ return DM_MAPIO_REQUEUE; clone->cmd_flags |= REQ_FAILFAST_TRANSPORT; r = map_io(m, clone, map_context, 0); if (r < 0 || r == DM_MAPIO_REQUEUE) clear_mapinfo(m, map_context); return r; } /* * Take a path out of use. */ static int fail_path(struct pgpath *pgpath) { unsigned long flags; struct multipath *m = pgpath->pg->m; spin_lock_irqsave(&m->lock, flags); if (!pgpath->is_active) goto out; DMWARN("Failing path %s.", pgpath->path.dev->name); pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path); pgpath->is_active = 0; pgpath->fail_count++; m->nr_valid_paths--; if (pgpath == m->current_pgpath) m->current_pgpath = NULL; dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti, pgpath->path.dev->name, m->nr_valid_paths); schedule_work(&m->trigger_event); out: spin_unlock_irqrestore(&m->lock, flags); return 0; } /* * Reinstate a previously-failed path */ static int reinstate_path(struct pgpath *pgpath) { int r = 0; unsigned long flags; struct multipath *m = pgpath->pg->m; spin_lock_irqsave(&m->lock, flags); if (pgpath->is_active) goto out; if (!pgpath->pg->ps.type->reinstate_path) { DMWARN("Reinstate path not supported by path selector %s", pgpath->pg->ps.type->name); r = -EINVAL; goto out; } r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path); if (r) goto out; pgpath->is_active = 1; if (!m->nr_valid_paths++ && m->queue_size) { 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.work)) m->pg_init_in_progress++; } dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti, pgpath->path.dev->name, m->nr_valid_paths); schedule_work(&m->trigger_event); out: spin_unlock_irqrestore(&m->lock, flags); return r; } /* * Fail or reinstate all paths that match the provided struct dm_dev. */ static int action_dev(struct multipath *m, struct dm_dev *dev, action_fn action) { int r = -EINVAL; struct pgpath *pgpath; struct priority_group *pg; list_for_each_entry(pg, &m->priority_groups, list) { list_for_each_entry(pgpath, &pg->pgpaths, list) { if (pgpath->path.dev == dev) r = action(pgpath); } } return r; } /* * Temporarily try to avoid having to use the specified PG */ static void bypass_pg(struct multipath *m, struct priority_group *pg, int bypassed) { unsigned long flags; spin_lock_irqsave(&m->lock, flags); pg->bypassed = bypassed; m->current_pgpath = NULL; m->current_pg = NULL; spin_unlock_irqrestore(&m->lock, flags); schedule_work(&m->trigger_event); } /* * Switch to using the specified PG from the next I/O that gets mapped */ static int switch_pg_num(struct multipath *m, const char *pgstr) { struct priority_group *pg; unsigned pgnum; unsigned long flags; char dummy; if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum || (pgnum > m->nr_priority_groups)) { DMWARN("invalid PG number supplied to switch_pg_num"); return -EINVAL; } spin_lock_irqsave(&m->lock, flags); list_for_each_entry(pg, &m->priority_groups, list) { pg->bypassed = 0; if (--pgnum) continue; m->current_pgpath = NULL; m->current_pg = NULL; m->next_pg = pg; } spin_unlock_irqrestore(&m->lock, flags); schedule_work(&m->trigger_event); return 0; } /* * Set/clear bypassed status of a PG. * PGs are numbered upwards from 1 in the order they were declared. */ static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed) { struct priority_group *pg; unsigned pgnum; char dummy; if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum || (pgnum > m->nr_priority_groups)) { DMWARN("invalid PG number supplied to bypass_pg"); return -EINVAL; } list_for_each_entry(pg, &m->priority_groups, list) { if (!--pgnum) break; } bypass_pg(m, pg, bypassed); return 0; } /* * Should we retry pg_init immediately? */ static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath) { unsigned long flags; int limit_reached = 0; spin_lock_irqsave(&m->lock, flags); if (m->pg_init_count <= m->pg_init_retries) m->pg_init_required = 1; else limit_reached = 1; spin_unlock_irqrestore(&m->lock, flags); return limit_reached; } static void pg_init_done(void *data, int errors) { struct pgpath *pgpath = data; struct priority_group *pg = pgpath->pg; struct multipath *m = pg->m; unsigned long flags; unsigned delay_retry = 0; /* device or driver problems */ switch (errors) { case SCSI_DH_OK: break; case SCSI_DH_NOSYS: if (!m->hw_handler_name) { errors = 0; break; } DMERR("Could not failover the device: Handler scsi_dh_%s " "Error %d.", m->hw_handler_name, errors); /* * Fail path for now, so we do not ping pong */ fail_path(pgpath); break; case SCSI_DH_DEV_TEMP_BUSY: /* * Probably doing something like FW upgrade on the * controller so try the other pg. */ bypass_pg(m, pg, 1); break; case SCSI_DH_RETRY: /* Wait before retrying. */ delay_retry = 1; case SCSI_DH_IMM_RETRY: case SCSI_DH_RES_TEMP_UNAVAIL: if (pg_init_limit_reached(m, pgpath)) fail_path(pgpath); errors = 0; break; default: /* * We probably do not want to fail the path for a device * error, but this is what the old dm did. In future * patches we can do more advanced handling. */ fail_path(pgpath); } spin_lock_irqsave(&m->lock, flags); if (errors) { if (pgpath == m->current_pgpath) { DMERR("Could not failover device. Error %d.", errors); m->current_pgpath = NULL; m->current_pg = NULL; } } else if (!m->pg_init_required) pg->bypassed = 0; if (--m->pg_init_in_progress) /* Activations of other paths are still on going */ goto out; if (!m->pg_init_required) m->queue_io = 0; m->pg_init_delay_retry = delay_retry; queue_work(kmultipathd, &m->process_queued_ios); /* * Wake up any thread waiting to suspend. */ wake_up(&m->pg_init_wait); out: spin_unlock_irqrestore(&m->lock, flags); } static void activate_path(struct work_struct *work) { struct pgpath *pgpath = container_of(work, struct pgpath, activate_path.work); scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev), pg_init_done, pgpath); } /* * end_io handling */ static int do_end_io(struct multipath *m, struct request *clone, int error, struct dm_mpath_io *mpio) { /* * We don't queue any clone request inside the multipath target * during end I/O handling, since those clone requests don't have * bio clones. If we queue them inside the multipath target, * we need to make bio clones, that requires memory allocation. * (See drivers/md/dm.c:end_clone_bio() about why the clone requests * don't have bio clones.) * Instead of queueing the clone request here, we queue the original * request into dm core, which will remake a clone request and * clone bios for it and resubmit it later. */ int r = DM_ENDIO_REQUEUE; unsigned long flags; if (!error && !clone->errors) return 0; /* I/O complete */ if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ) return error; if (mpio->pgpath) fail_path(mpio->pgpath); spin_lock_irqsave(&m->lock, flags); if (!m->nr_valid_paths) { if (!m->queue_if_no_path) { if (!__must_push_back(m)) r = -EIO; } else { if (error == -EBADE) r = error; } } spin_unlock_irqrestore(&m->lock, flags); return r; } static int multipath_end_io(struct dm_target *ti, struct request *clone, int error, union map_info *map_context) { struct multipath *m = ti->private; struct dm_mpath_io *mpio = map_context->ptr; struct pgpath *pgpath; struct path_selector *ps; int r; BUG_ON(!mpio); r = do_end_io(m, clone, error, mpio); pgpath = mpio->pgpath; if (pgpath) { ps = &pgpath->pg->ps; if (ps->type->end_io) ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes); } clear_mapinfo(m, map_context); return r; } /* * Suspend can't complete until all the I/O is processed so if * the last path fails we must error any remaining I/O. * Note that if the freeze_bdev fails while suspending, the * queue_if_no_path state is lost - userspace should reset it. */ static void multipath_presuspend(struct dm_target *ti) { struct multipath *m = (struct multipath *) ti->private; queue_if_no_path(m, 0, 1); } static void multipath_postsuspend(struct dm_target *ti) { struct multipath *m = ti->private; mutex_lock(&m->work_mutex); flush_multipath_work(m); mutex_unlock(&m->work_mutex); } /* * Restore the queue_if_no_path setting. */ static void multipath_resume(struct dm_target *ti) { struct multipath *m = (struct multipath *) ti->private; unsigned long flags; spin_lock_irqsave(&m->lock, flags); m->queue_if_no_path = m->saved_queue_if_no_path; spin_unlock_irqrestore(&m->lock, flags); } /* * Info output has the following format: * num_multipath_feature_args [multipath_feature_args]* * num_handler_status_args [handler_status_args]* * num_groups init_group_number * [A|D|E num_ps_status_args [ps_status_args]* * num_paths num_selector_args * [path_dev A|F fail_count [selector_args]* ]+ ]+ * * Table output has the following format (identical to the constructor string): * num_feature_args [features_args]* * num_handler_args hw_handler [hw_handler_args]* * num_groups init_group_number * [priority selector-name num_ps_args [ps_args]* * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+ */ static int multipath_status(struct dm_target *ti, status_type_t type, unsigned status_flags, char *result, unsigned maxlen) { int sz = 0; unsigned long flags; struct multipath *m = (struct multipath *) ti->private; struct priority_group *pg; struct pgpath *p; unsigned pg_num; char state; spin_lock_irqsave(&m->lock, flags); /* Features */ if (type == STATUSTYPE_INFO) 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_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 + m->retain_attached_hw_handler); 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_msecs != DM_PG_INIT_DELAY_DEFAULT) DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs); if (m->retain_attached_hw_handler) DMEMIT("retain_attached_hw_handler "); } if (!m->hw_handler_name || type == STATUSTYPE_INFO) DMEMIT("0 "); else DMEMIT("1 %s ", m->hw_handler_name); DMEMIT("%u ", m->nr_priority_groups); if (m->next_pg) pg_num = m->next_pg->pg_num; else if (m->current_pg) pg_num = m->current_pg->pg_num; else pg_num = (m->nr_priority_groups ? 1 : 0); DMEMIT("%u ", pg_num); switch (type) { case STATUSTYPE_INFO: list_for_each_entry(pg, &m->priority_groups, list) { if (pg->bypassed) state = 'D'; /* Disabled */ else if (pg == m->current_pg) state = 'A'; /* Currently Active */ else state = 'E'; /* Enabled */ DMEMIT("%c ", state); if (pg->ps.type->status) sz += pg->ps.type->status(&pg->ps, NULL, type, result + sz, maxlen - sz); else DMEMIT("0 "); DMEMIT("%u %u ", pg->nr_pgpaths, pg->ps.type->info_args); list_for_each_entry(p, &pg->pgpaths, list) { DMEMIT("%s %s %u ", p->path.dev->name, p->is_active ? "A" : "F", p->fail_count); if (pg->ps.type->status) sz += pg->ps.type->status(&pg->ps, &p->path, type, result + sz, maxlen - sz); } } break; case STATUSTYPE_TABLE: list_for_each_entry(pg, &m->priority_groups, list) { DMEMIT("%s ", pg->ps.type->name); if (pg->ps.type->status) sz += pg->ps.type->status(&pg->ps, NULL, type, result + sz, maxlen - sz); else DMEMIT("0 "); DMEMIT("%u %u ", pg->nr_pgpaths, pg->ps.type->table_args); list_for_each_entry(p, &pg->pgpaths, list) { DMEMIT("%s ", p->path.dev->name); if (pg->ps.type->status) sz += pg->ps.type->status(&pg->ps, &p->path, type, result + sz, maxlen - sz); } } break; } spin_unlock_irqrestore(&m->lock, flags); return 0; } static int multipath_message(struct dm_target *ti, unsigned argc, char **argv) { int r = -EINVAL; struct dm_dev *dev; struct multipath *m = (struct multipath *) ti->private; action_fn action; mutex_lock(&m->work_mutex); if (dm_suspended(ti)) { r = -EBUSY; goto out; } if (argc == 1) { if (!strcasecmp(argv[0], "queue_if_no_path")) { r = queue_if_no_path(m, 1, 0); goto out; } else if (!strcasecmp(argv[0], "fail_if_no_path")) { r = queue_if_no_path(m, 0, 0); goto out; } } if (argc != 2) { DMWARN("Unrecognised multipath message received."); goto out; } if (!strcasecmp(argv[0], "disable_group")) { r = bypass_pg_num(m, argv[1], 1); goto out; } else if (!strcasecmp(argv[0], "enable_group")) { r = bypass_pg_num(m, argv[1], 0); goto out; } else if (!strcasecmp(argv[0], "switch_group")) { r = switch_pg_num(m, argv[1]); goto out; } else if (!strcasecmp(argv[0], "reinstate_path")) action = reinstate_path; else if (!strcasecmp(argv[0], "fail_path")) action = fail_path; else { DMWARN("Unrecognised multipath message received."); goto out; } r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev); if (r) { DMWARN("message: error getting device %s", argv[1]); goto out; } r = action_dev(m, dev, action); dm_put_device(ti, dev); out: mutex_unlock(&m->work_mutex); return r; } static int multipath_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg) { struct multipath *m = ti->private; struct pgpath *pgpath; struct block_device *bdev; fmode_t mode; unsigned long flags; int r; again: bdev = NULL; mode = 0; r = 0; spin_lock_irqsave(&m->lock, flags); if (!m->current_pgpath) __choose_pgpath(m, 0); pgpath = m->current_pgpath; if (pgpath) { bdev = pgpath->path.dev->bdev; mode = pgpath->path.dev->mode; } if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path)) r = -EAGAIN; else if (!bdev) r = -EIO; spin_unlock_irqrestore(&m->lock, flags); /* * Only pass ioctls through if the device sizes match exactly. */ if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT) r = scsi_verify_blk_ioctl(NULL, cmd); if (r == -EAGAIN && !fatal_signal_pending(current)) { queue_work(kmultipathd, &m->process_queued_ios); msleep(10); goto again; } return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg); } static int multipath_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data) { struct multipath *m = ti->private; struct priority_group *pg; struct pgpath *p; int ret = 0; list_for_each_entry(pg, &m->priority_groups, list) { list_for_each_entry(p, &pg->pgpaths, list) { ret = fn(ti, p->path.dev, ti->begin, ti->len, data); if (ret) goto out; } } out: return ret; } static int __pgpath_busy(struct pgpath *pgpath) { struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev); return dm_underlying_device_busy(q); } /* * We return "busy", only when we can map I/Os but underlying devices * are busy (so even if we map I/Os now, the I/Os will wait on * the underlying queue). * In other words, if we want to kill I/Os or queue them inside us * due to map unavailability, we don't return "busy". Otherwise, * dm core won't give us the I/Os and we can't do what we want. */ static int multipath_busy(struct dm_target *ti) { int busy = 0, has_active = 0; struct multipath *m = ti->private; struct priority_group *pg; struct pgpath *pgpath; unsigned long flags; spin_lock_irqsave(&m->lock, flags); /* Guess which priority_group will be used at next mapping time */ if (unlikely(!m->current_pgpath && m->next_pg)) pg = m->next_pg; else if (likely(m->current_pg)) pg = m->current_pg; else /* * We don't know which pg will be used at next mapping time. * We don't call __choose_pgpath() here to avoid to trigger * pg_init just by busy checking. * So we don't know whether underlying devices we will be using * at next mapping time are busy or not. Just try mapping. */ goto out; /* * If there is one non-busy active path at least, the path selector * will be able to select it. So we consider such a pg as not busy. */ busy = 1; list_for_each_entry(pgpath, &pg->pgpaths, list) if (pgpath->is_active) { has_active = 1; if (!__pgpath_busy(pgpath)) { busy = 0; break; } } if (!has_active) /* * No active path in this pg, so this pg won't be used and * the current_pg will be changed at next mapping time. * We need to try mapping to determine it. */ busy = 0; out: spin_unlock_irqrestore(&m->lock, flags); return busy; } /*----------------------------------------------------------------- * Module setup *---------------------------------------------------------------*/ static struct target_type multipath_target = { .name = "multipath", .version = {1, 5, 0}, .module = THIS_MODULE, .ctr = multipath_ctr, .dtr = multipath_dtr, .map_rq = multipath_map, .rq_end_io = multipath_end_io, .presuspend = multipath_presuspend, .postsuspend = multipath_postsuspend, .resume = multipath_resume, .status = multipath_status, .message = multipath_message, .ioctl = multipath_ioctl, .iterate_devices = multipath_iterate_devices, .busy = multipath_busy, }; static int __init dm_multipath_init(void) { int r; /* allocate a slab for the dm_ios */ _mpio_cache = KMEM_CACHE(dm_mpath_io, 0); if (!_mpio_cache) return -ENOMEM; r = dm_register_target(&multipath_target); if (r < 0) { DMERR("register failed %d", r); kmem_cache_destroy(_mpio_cache); return -EINVAL; } kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0); if (!kmultipathd) { DMERR("failed to create workqueue kmpathd"); dm_unregister_target(&multipath_target); kmem_cache_destroy(_mpio_cache); return -ENOMEM; } /* * A separate workqueue is used to handle the device handlers * to avoid overloading existing workqueue. Overloading the * old workqueue would also create a bottleneck in the * path of the storage hardware device activation. */ kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd", WQ_MEM_RECLAIM); if (!kmpath_handlerd) { DMERR("failed to create workqueue kmpath_handlerd"); destroy_workqueue(kmultipathd); dm_unregister_target(&multipath_target); kmem_cache_destroy(_mpio_cache); return -ENOMEM; } DMINFO("version %u.%u.%u loaded", multipath_target.version[0], multipath_target.version[1], multipath_target.version[2]); return r; } static void __exit dm_multipath_exit(void) { destroy_workqueue(kmpath_handlerd); destroy_workqueue(kmultipathd); dm_unregister_target(&multipath_target); kmem_cache_destroy(_mpio_cache); } module_init(dm_multipath_init); module_exit(dm_multipath_exit); MODULE_DESCRIPTION(DM_NAME " multipath target"); MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>"); MODULE_LICENSE("GPL");