| /* |
| * 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 <scsi/scsi_dh.h> |
| #include <asm/atomic.h> |
| |
| #define DM_MSG_PREFIX "multipath" |
| #define MESG_STR(x) x, sizeof(x) |
| #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; |
| |
| spinlock_t lock; |
| |
| const char *hw_handler_name; |
| char *hw_handler_params; |
| |
| 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; /* Must we queue all I/O? */ |
| unsigned queue_if_no_path; /* Queue I/O if last path fails? */ |
| 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_msecs; /* Number of msecs before pg_init retry */ |
| |
| struct work_struct process_queued_ios; |
| struct list_head queued_ios; |
| unsigned queue_size; |
| |
| 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); |
| } |
| |
| |
| /*----------------------------------------------- |
| * 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. |
| */ |
| do { |
| list_for_each_entry(pg, &m->priority_groups, list) { |
| if (pg->bypassed == bypassed) |
| continue; |
| if (!__choose_path_in_pg(m, pg, nr_bytes)) |
| 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, |
| struct dm_mpath_io *mpio, 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; |
| |
| 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; |
| struct dm_mpath_io *mpio; |
| 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); |
| mpio = info->ptr; |
| |
| r = map_io(m, clone, mpio, 1); |
| if (r < 0) { |
| mempool_free(mpio, m->mpio_pool); |
| dm_kill_unmapped_request(clone, r); |
| } else if (r == DM_MAPIO_REMAPPED) |
| dm_dispatch_request(clone); |
| else if (r == DM_MAPIO_REQUEUE) { |
| mempool_free(mpio, m->mpio_pool); |
| 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->queue_size) |
| goto out; |
| |
| 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); |
| |
| out: |
| 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>]* ]+ ]+ |
| *---------------------------------------------------------------*/ |
| struct param { |
| unsigned min; |
| unsigned max; |
| char *error; |
| }; |
| |
| static int read_param(struct param *param, char *str, unsigned *v, char **error) |
| { |
| if (!str || |
| (sscanf(str, "%u", v) != 1) || |
| (*v < param->min) || |
| (*v > param->max)) { |
| *error = param->error; |
| return -EINVAL; |
| } |
| |
| return 0; |
| } |
| |
| struct arg_set { |
| unsigned argc; |
| char **argv; |
| }; |
| |
| static char *shift(struct arg_set *as) |
| { |
| char *r; |
| |
| if (as->argc) { |
| as->argc--; |
| r = *as->argv; |
| as->argv++; |
| return r; |
| } |
| |
| return NULL; |
| } |
| |
| static void consume(struct arg_set *as, unsigned n) |
| { |
| BUG_ON (as->argc < n); |
| as->argc -= n; |
| as->argv += n; |
| } |
| |
| static int parse_path_selector(struct arg_set *as, struct priority_group *pg, |
| struct dm_target *ti) |
| { |
| int r; |
| struct path_selector_type *pst; |
| unsigned ps_argc; |
| |
| static struct param _params[] = { |
| {0, 1024, "invalid number of path selector args"}, |
| }; |
| |
| pst = dm_get_path_selector(shift(as)); |
| if (!pst) { |
| ti->error = "unknown path selector type"; |
| return -EINVAL; |
| } |
| |
| r = read_param(_params, shift(as), &ps_argc, &ti->error); |
| if (r) { |
| dm_put_path_selector(pst); |
| return -EINVAL; |
| } |
| |
| if (ps_argc > as->argc) { |
| dm_put_path_selector(pst); |
| ti->error = "not enough arguments for path selector"; |
| 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; |
| consume(as, ps_argc); |
| |
| return 0; |
| } |
| |
| static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, |
| struct dm_target *ti) |
| { |
| int r; |
| struct pgpath *p; |
| struct multipath *m = ti->private; |
| |
| /* 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, shift(as), dm_table_get_mode(ti->table), |
| &p->path.dev); |
| if (r) { |
| ti->error = "error getting device"; |
| goto bad; |
| } |
| |
| if (m->hw_handler_name) { |
| struct request_queue *q = bdev_get_queue(p->path.dev->bdev); |
| |
| 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 arg_set *as, |
| struct multipath *m) |
| { |
| static struct param _params[] = { |
| {1, 1024, "invalid number of paths"}, |
| {0, 1024, "invalid number of selector args"} |
| }; |
| |
| int r; |
| unsigned i, nr_selector_args, nr_params; |
| 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 = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error); |
| if (r) |
| goto bad; |
| |
| r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error); |
| if (r) |
| goto bad; |
| |
| nr_params = 1 + nr_selector_args; |
| for (i = 0; i < pg->nr_pgpaths; i++) { |
| struct pgpath *pgpath; |
| struct arg_set path_args; |
| |
| if (as->argc < nr_params) { |
| ti->error = "not enough path parameters"; |
| r = -EINVAL; |
| goto bad; |
| } |
| |
| path_args.argc = nr_params; |
| 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); |
| consume(as, nr_params); |
| } |
| |
| return pg; |
| |
| bad: |
| free_priority_group(pg, ti); |
| return ERR_PTR(r); |
| } |
| |
| static int parse_hw_handler(struct arg_set *as, struct multipath *m) |
| { |
| unsigned hw_argc; |
| int ret; |
| struct dm_target *ti = m->ti; |
| |
| static struct param _params[] = { |
| {0, 1024, "invalid number of hardware handler args"}, |
| }; |
| |
| if (read_param(_params, shift(as), &hw_argc, &ti->error)) |
| return -EINVAL; |
| |
| if (!hw_argc) |
| return 0; |
| |
| if (hw_argc > as->argc) { |
| ti->error = "not enough arguments for hardware handler"; |
| return -EINVAL; |
| } |
| |
| m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL); |
| request_module("scsi_dh_%s", m->hw_handler_name); |
| if (scsi_dh_handler_exist(m->hw_handler_name) == 0) { |
| 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]); |
| } |
| consume(as, hw_argc - 1); |
| |
| return 0; |
| fail: |
| kfree(m->hw_handler_name); |
| m->hw_handler_name = NULL; |
| return ret; |
| } |
| |
| static int parse_features(struct arg_set *as, struct multipath *m) |
| { |
| int r; |
| unsigned argc; |
| struct dm_target *ti = m->ti; |
| const char *param_name; |
| |
| static struct param _params[] = { |
| {0, 5, "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 = read_param(_params, shift(as), &argc, &ti->error); |
| if (r) |
| return -EINVAL; |
| |
| if (!argc) |
| return 0; |
| |
| if (argc > as->argc) { |
| ti->error = "not enough arguments for features"; |
| return -EINVAL; |
| } |
| |
| do { |
| param_name = shift(as); |
| argc--; |
| |
| if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) { |
| r = queue_if_no_path(m, 1, 0); |
| continue; |
| } |
| |
| if (!strnicmp(param_name, MESG_STR("pg_init_retries")) && |
| (argc >= 1)) { |
| r = read_param(_params + 1, shift(as), |
| &m->pg_init_retries, &ti->error); |
| argc--; |
| continue; |
| } |
| |
| if (!strnicmp(param_name, MESG_STR("pg_init_delay_msecs")) && |
| (argc >= 1)) { |
| r = read_param(_params + 2, shift(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 parameters */ |
| static struct param _params[] = { |
| {0, 1024, "invalid number of priority groups"}, |
| {0, 1024, "invalid initial priority group number"}, |
| }; |
| |
| int r; |
| struct multipath *m; |
| struct 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 = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error); |
| if (r) |
| goto bad; |
| |
| r = read_param(_params + 1, shift(&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_sync(&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 dm_mpath_io *mpio; |
| struct multipath *m = (struct multipath *) ti->private; |
| |
| mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC); |
| if (!mpio) |
| /* ENOMEM, requeue */ |
| return DM_MAPIO_REQUEUE; |
| memset(mpio, 0, sizeof(*mpio)); |
| |
| map_context->ptr = mpio; |
| clone->cmd_flags |= REQ_FAILFAST_TRANSPORT; |
| r = map_io(m, clone, mpio, 0); |
| if (r < 0 || r == DM_MAPIO_REQUEUE) |
| mempool_free(mpio, m->mpio_pool); |
| |
| 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; |
| |
| if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 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; |
| |
| if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 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 = mpio->pgpath; |
| struct path_selector *ps; |
| int r; |
| |
| r = do_end_io(m, clone, error, mpio); |
| if (pgpath) { |
| ps = &pgpath->pg->ps; |
| if (ps->type->end_io) |
| ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes); |
| } |
| mempool_free(mpio, m->mpio_pool); |
| |
| 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, |
| char *result, unsigned int 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); |
| 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->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 (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) { |
| r = queue_if_no_path(m, 1, 0); |
| goto out; |
| } else if (!strnicmp(argv[0], MESG_STR("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 (!strnicmp(argv[0], MESG_STR("disable_group"))) { |
| r = bypass_pg_num(m, argv[1], 1); |
| goto out; |
| } else if (!strnicmp(argv[0], MESG_STR("enable_group"))) { |
| r = bypass_pg_num(m, argv[1], 0); |
| goto out; |
| } else if (!strnicmp(argv[0], MESG_STR("switch_group"))) { |
| r = switch_pg_num(m, argv[1]); |
| goto out; |
| } else if (!strnicmp(argv[0], MESG_STR("reinstate_path"))) |
| action = reinstate_path; |
| else if (!strnicmp(argv[0], MESG_STR("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 = (struct multipath *) ti->private; |
| struct block_device *bdev = NULL; |
| fmode_t mode = 0; |
| unsigned long flags; |
| int r = 0; |
| |
| spin_lock_irqsave(&m->lock, flags); |
| |
| if (!m->current_pgpath) |
| __choose_pgpath(m, 0); |
| |
| if (m->current_pgpath) { |
| bdev = m->current_pgpath->path.dev->bdev; |
| mode = m->current_pgpath->path.dev->mode; |
| } |
| |
| if (m->queue_io) |
| 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); |
| |
| 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, 3, 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"); |