diff options
Diffstat (limited to 'drivers/md/dm-mpath.c')
| -rw-r--r-- | drivers/md/dm-mpath.c | 1302 |
1 files changed, 1302 insertions, 0 deletions
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c new file mode 100644 index 00000000000..43763a0bd09 --- /dev/null +++ b/drivers/md/dm-mpath.c @@ -0,0 +1,1302 @@ +/* + * Copyright (C) 2003 Sistina Software Limited. + * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved. + * + * This file is released under the GPL. + */ + +#include "dm.h" +#include "dm-path-selector.h" +#include "dm-hw-handler.h" +#include "dm-bio-list.h" +#include "dm-bio-record.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 <asm/atomic.h> + +#define MESG_STR(x) x, sizeof(x) + +/* Path properties */ +struct pgpath { + struct list_head list; + + struct priority_group *pg; /* Owning PG */ + unsigned fail_count; /* Cumulative failure count */ + + struct path 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; + + struct hw_handler hw_handler; + unsigned nr_priority_groups; + struct list_head priority_groups; + unsigned pg_init_required; /* pg_init needs calling? */ + + 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 suspended; /* Has dm core suspended our I/O? */ + + struct work_struct process_queued_ios; + struct bio_list queued_ios; + unsigned queue_size; + + struct work_struct trigger_event; + + /* + * We must use a mempool of mpath_io structs so that we + * can resubmit bios on error. + */ + mempool_t *mpio_pool; +}; + +/* + * Context information attached to each bio we process. + */ +struct mpath_io { + struct pgpath *pgpath; + struct dm_bio_details details; +}; + +typedef int (*action_fn) (struct pgpath *pgpath); + +#define MIN_IOS 256 /* Mempool size */ + +static kmem_cache_t *_mpio_cache; + +static void process_queued_ios(void *data); +static void trigger_event(void *data); + + +/*----------------------------------------------- + * Allocation routines + *-----------------------------------------------*/ + +static struct pgpath *alloc_pgpath(void) +{ + struct pgpath *pgpath = kmalloc(sizeof(*pgpath), GFP_KERNEL); + + if (pgpath) { + memset(pgpath, 0, sizeof(*pgpath)); + pgpath->path.is_active = 1; + } + + return pgpath; +} + +static inline void free_pgpath(struct pgpath *pgpath) +{ + kfree(pgpath); +} + +static struct priority_group *alloc_priority_group(void) +{ + struct priority_group *pg; + + pg = kmalloc(sizeof(*pg), GFP_KERNEL); + if (!pg) + return NULL; + + memset(pg, 0, sizeof(*pg)); + INIT_LIST_HEAD(&pg->pgpaths); + + return pg; +} + +static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti) +{ + struct pgpath *pgpath, *tmp; + + list_for_each_entry_safe(pgpath, tmp, pgpaths, list) { + list_del(&pgpath->list); + 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(void) +{ + struct multipath *m; + + m = kmalloc(sizeof(*m), GFP_KERNEL); + if (m) { + memset(m, 0, sizeof(*m)); + INIT_LIST_HEAD(&m->priority_groups); + spin_lock_init(&m->lock); + m->queue_io = 1; + INIT_WORK(&m->process_queued_ios, process_queued_ios, m); + INIT_WORK(&m->trigger_event, trigger_event, m); + m->mpio_pool = mempool_create(MIN_IOS, mempool_alloc_slab, + mempool_free_slab, _mpio_cache); + if (!m->mpio_pool) { + kfree(m); + return NULL; + } + } + + return m; +} + +static void free_multipath(struct multipath *m) +{ + struct priority_group *pg, *tmp; + struct hw_handler *hwh = &m->hw_handler; + + list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) { + list_del(&pg->list); + free_priority_group(pg, m->ti); + } + + if (hwh->type) { + hwh->type->destroy(hwh); + dm_put_hw_handler(hwh->type); + } + + mempool_destroy(m->mpio_pool); + kfree(m); +} + + +/*----------------------------------------------- + * Path selection + *-----------------------------------------------*/ + +static void __switch_pg(struct multipath *m, struct pgpath *pgpath) +{ + struct hw_handler *hwh = &m->hw_handler; + + m->current_pg = pgpath->pg; + + /* Must we initialise the PG first, and queue I/O till it's ready? */ + if (hwh->type && hwh->type->pg_init) { + m->pg_init_required = 1; + m->queue_io = 1; + } else { + m->pg_init_required = 0; + m->queue_io = 0; + } +} + +static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg) +{ + struct path *path; + + path = pg->ps.type->select_path(&pg->ps, &m->repeat_count); + 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) +{ + 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)) + return; + } + + /* Don't change PG until it has no remaining paths */ + if (m->current_pg && !__choose_path_in_pg(m, m->current_pg)) + 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)) + return; + } + } while (bypassed--); + +failed: + m->current_pgpath = NULL; + m->current_pg = NULL; +} + +static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio, + unsigned was_queued) +{ + int r = 1; + unsigned long flags; + struct pgpath *pgpath; + + 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); + + pgpath = m->current_pgpath; + + if (was_queued) + m->queue_size--; + + if ((pgpath && m->queue_io) || + (!pgpath && m->queue_if_no_path && !m->suspended)) { + /* Queue for the daemon to resubmit */ + bio_list_add(&m->queued_ios, bio); + m->queue_size++; + if (m->pg_init_required || !m->queue_io) + schedule_work(&m->process_queued_ios); + pgpath = NULL; + r = 0; + } else if (!pgpath) + r = -EIO; /* Failed */ + else + bio->bi_bdev = pgpath->path.dev->bdev; + + mpio->pgpath = pgpath; + + 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 long flags; + + spin_lock_irqsave(&m->lock, flags); + + m->queue_if_no_path = queue_if_no_path; + if (!m->queue_if_no_path) + schedule_work(&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 bio *bio = NULL, *next; + struct mpath_io *mpio; + union map_info *info; + + spin_lock_irqsave(&m->lock, flags); + bio = bio_list_get(&m->queued_ios); + spin_unlock_irqrestore(&m->lock, flags); + + while (bio) { + next = bio->bi_next; + bio->bi_next = NULL; + + info = dm_get_mapinfo(bio); + mpio = info->ptr; + + r = map_io(m, bio, mpio, 1); + if (r < 0) + bio_endio(bio, bio->bi_size, r); + else if (r == 1) + generic_make_request(bio); + + bio = next; + } +} + +static void process_queued_ios(void *data) +{ + struct multipath *m = (struct multipath *) data; + struct hw_handler *hwh = &m->hw_handler; + struct pgpath *pgpath; + unsigned init_required, must_queue = 0; + unsigned long flags; + + spin_lock_irqsave(&m->lock, flags); + + if (!m->current_pgpath) + __choose_pgpath(m); + + pgpath = m->current_pgpath; + + if ((pgpath && m->queue_io) || + (!pgpath && m->queue_if_no_path && !m->suspended)) + must_queue = 1; + + init_required = m->pg_init_required; + if (init_required) + m->pg_init_required = 0; + + spin_unlock_irqrestore(&m->lock, flags); + + if (init_required) + hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path); + + 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(void *data) +{ + struct multipath *m = (struct multipath *) data; + + 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; +}; + +#define ESTR(s) ("dm-multipath: " s) + +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, ESTR("invalid number of path selector args")}, + }; + + pst = dm_get_path_selector(shift(as)); + if (!pst) { + ti->error = ESTR("unknown path selector type"); + return -EINVAL; + } + + r = read_param(_params, shift(as), &ps_argc, &ti->error); + if (r) + return -EINVAL; + + r = pst->create(&pg->ps, ps_argc, as->argv); + if (r) { + dm_put_path_selector(pst); + ti->error = ESTR("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; + + /* we need at least a path arg */ + if (as->argc < 1) { + ti->error = ESTR("no device given"); + return NULL; + } + + p = alloc_pgpath(); + if (!p) + return NULL; + + r = dm_get_device(ti, shift(as), ti->begin, ti->len, + dm_table_get_mode(ti->table), &p->path.dev); + if (r) { + ti->error = ESTR("error getting device"); + 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 NULL; +} + +static struct priority_group *parse_priority_group(struct arg_set *as, + struct multipath *m, + struct dm_target *ti) +{ + static struct param _params[] = { + {1, 1024, ESTR("invalid number of paths")}, + {0, 1024, ESTR("invalid number of selector args")} + }; + + int r; + unsigned i, nr_selector_args, nr_params; + struct priority_group *pg; + + if (as->argc < 2) { + as->argc = 0; + ti->error = ESTR("not enough priority group aruments"); + return NULL; + } + + pg = alloc_priority_group(); + if (!pg) { + ti->error = ESTR("couldn't allocate priority group"); + return NULL; + } + 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) + goto bad; + + path_args.argc = nr_params; + path_args.argv = as->argv; + + pgpath = parse_path(&path_args, &pg->ps, ti); + if (!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 NULL; +} + +static int parse_hw_handler(struct arg_set *as, struct multipath *m, + struct dm_target *ti) +{ + int r; + struct hw_handler_type *hwht; + unsigned hw_argc; + + static struct param _params[] = { + {0, 1024, ESTR("invalid number of hardware handler args")}, + }; + + r = read_param(_params, shift(as), &hw_argc, &ti->error); + if (r) + return -EINVAL; + + if (!hw_argc) + return 0; + + hwht = dm_get_hw_handler(shift(as)); + if (!hwht) { + ti->error = ESTR("unknown hardware handler type"); + return -EINVAL; + } + + r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv); + if (r) { + dm_put_hw_handler(hwht); + ti->error = ESTR("hardware handler constructor failed"); + return r; + } + + m->hw_handler.type = hwht; + consume(as, hw_argc - 1); + + return 0; +} + +static int parse_features(struct arg_set *as, struct multipath *m, + struct dm_target *ti) +{ + int r; + unsigned argc; + + static struct param _params[] = { + {0, 1, ESTR("invalid number of feature args")}, + }; + + r = read_param(_params, shift(as), &argc, &ti->error); + if (r) + return -EINVAL; + + if (!argc) + return 0; + + if (!strnicmp(shift(as), MESG_STR("queue_if_no_path"))) + return queue_if_no_path(m, 1); + else { + ti->error = "Unrecognised multipath feature request"; + return -EINVAL; + } +} + +static int multipath_ctr(struct dm_target *ti, unsigned int argc, + char **argv) +{ + /* target parameters */ + static struct param _params[] = { + {1, 1024, ESTR("invalid number of priority groups")}, + {1, 1024, ESTR("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(); + if (!m) { + ti->error = ESTR("can't allocate multipath"); + return -EINVAL; + } + + r = parse_features(&as, m, ti); + if (r) + goto bad; + + r = parse_hw_handler(&as, m, ti); + 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; + + /* parse the priority groups */ + while (as.argc) { + struct priority_group *pg; + + pg = parse_priority_group(&as, m, ti); + if (!pg) { + r = -EINVAL; + 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 = ESTR("priority group count mismatch"); + r = -EINVAL; + goto bad; + } + + ti->private = m; + m->ti = ti; + + return 0; + + bad: + free_multipath(m); + return r; +} + +static void multipath_dtr(struct dm_target *ti) +{ + struct multipath *m = (struct multipath *) ti->private; + free_multipath(m); +} + +/* + * Map bios, recording original fields for later in case we have to resubmit + */ +static int multipath_map(struct dm_target *ti, struct bio *bio, + union map_info *map_context) +{ + int r; + struct mpath_io *mpio; + struct multipath *m = (struct multipath *) ti->private; + + mpio = mempool_alloc(m->mpio_pool, GFP_NOIO); + dm_bio_record(&mpio->details, bio); + + map_context->ptr = mpio; + bio->bi_rw |= (1 << BIO_RW_FAILFAST); + r = map_io(m, bio, mpio, 0); + if (r < 0) + 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->path.is_active) + goto out; + + DMWARN("dm-multipath: Failing path %s.", pgpath->path.dev->name); + + pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path); + pgpath->path.is_active = 0; + pgpath->fail_count++; + + m->nr_valid_paths--; + + if (pgpath == m->current_pgpath) + m->current_pgpath = NULL; + + 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->path.is_active) + goto out; + + if (!pgpath->pg->ps.type) { + 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->path.is_active = 1; + + m->current_pgpath = NULL; + if (!m->nr_valid_paths++) + schedule_work(&m->process_queued_ios); + + 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 = 0; + 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; +} + +/* + * pg_init must call this when it has completed its initialisation + */ +void dm_pg_init_complete(struct path *path, unsigned err_flags) +{ + struct pgpath *pgpath = path_to_pgpath(path); + struct priority_group *pg = pgpath->pg; + struct multipath *m = pg->m; + unsigned long flags; + + /* We insist on failing the path if the PG is already bypassed. */ + if (err_flags && pg->bypassed) + err_flags |= MP_FAIL_PATH; + + if (err_flags & MP_FAIL_PATH) + fail_path(pgpath); + + if (err_flags & MP_BYPASS_PG) + bypass_pg(m, pg, 1); + + spin_lock_irqsave(&m->lock, flags); + if (!err_flags) + m->queue_io = 0; + else { + m->current_pgpath = NULL; + m->current_pg = NULL; + } + schedule_work(&m->process_queued_ios); + spin_unlock_irqrestore(&m->lock, flags); +} + +/* + * end_io handling + */ +static int do_end_io(struct multipath *m, struct bio *bio, + int error, struct mpath_io *mpio) +{ + struct hw_handler *hwh = &m->hw_handler; + unsigned err_flags = MP_FAIL_PATH; /* Default behavior */ + + if (!error) + return 0; /* I/O complete */ + + spin_lock(&m->lock); + if (!m->nr_valid_paths) { + if (!m->queue_if_no_path || m->suspended) { + spin_unlock(&m->lock); + return -EIO; + } else { + spin_unlock(&m->lock); + goto requeue; + } + } + spin_unlock(&m->lock); + + if (hwh->type && hwh->type->error) + err_flags = hwh->type->error(hwh, bio); + + if (mpio->pgpath) { + if (err_flags & MP_FAIL_PATH) + fail_path(mpio->pgpath); + + if (err_flags & MP_BYPASS_PG) + bypass_pg(m, mpio->pgpath->pg, 1); + } + + if (err_flags & MP_ERROR_IO) + return -EIO; + + requeue: + dm_bio_restore(&mpio->details, bio); + + /* queue for the daemon to resubmit or fail */ + spin_lock(&m->lock); + bio_list_add(&m->queued_ios, bio); + m->queue_size++; + if (!m->queue_io) + schedule_work(&m->process_queued_ios); + spin_unlock(&m->lock); + + return 1; /* io not complete */ +} + +static int multipath_end_io(struct dm_target *ti, struct bio *bio, + int error, union map_info *map_context) +{ + struct multipath *m = (struct multipath *) ti->private; + struct mpath_io *mpio = (struct mpath_io *) map_context->ptr; + struct pgpath *pgpath = mpio->pgpath; + struct path_selector *ps; + int r; + + r = do_end_io(m, bio, error, mpio); + if (pgpath) { + ps = &pgpath->pg->ps; + if (ps->type->end_io) + ps->type->end_io(ps, &pgpath->path); + } + if (r <= 0) + mempool_free(mpio, m->mpio_pool); + + return r; +} + +/* + * Suspend can't complete until all the I/O is processed so if + * the last path failed we will now error any queued I/O. + */ +static void multipath_presuspend(struct dm_target *ti) +{ + struct multipath *m = (struct multipath *) ti->private; + unsigned long flags; + + spin_lock_irqsave(&m->lock, flags); + m->suspended = 1; + if (m->queue_if_no_path) + schedule_work(&m->process_queued_ios); + spin_unlock_irqrestore(&m->lock, flags); +} + +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->suspended = 0; + 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 hw_handler *hwh = &m->hw_handler; + struct priority_group *pg; + struct pgpath *p; + unsigned pg_num; + char state; + + spin_lock_irqsave(&m->lock, flags); + + /* Features */ + if (type == STATUSTYPE_INFO) + DMEMIT("1 %u ", m->queue_size); + else if (m->queue_if_no_path) + DMEMIT("1 queue_if_no_path "); + else + DMEMIT("0 "); + + if (hwh->type && hwh->type->status) + sz += hwh->type->status(hwh, type, result + sz, maxlen - sz); + else if (!hwh->type || type == STATUSTYPE_INFO) + DMEMIT("0 "); + else + DMEMIT("1 %s ", hwh->type->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 = 1; + + 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->path.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; + struct dm_dev *dev; + struct multipath *m = (struct multipath *) ti->private; + action_fn action; + + if (argc == 1) { + if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) + return queue_if_no_path(m, 1); + else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) + return queue_if_no_path(m, 0); + } + + if (argc != 2) + goto error; + + if (!strnicmp(argv[0], MESG_STR("disable_group"))) + return bypass_pg_num(m, argv[1], 1); + else if (!strnicmp(argv[0], MESG_STR("enable_group"))) + return bypass_pg_num(m, argv[1], 0); + else if (!strnicmp(argv[0], MESG_STR("switch_group"))) + return switch_pg_num(m, argv[1]); + 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 + goto error; + + r = dm_get_device(ti, argv[1], ti->begin, ti->len, + dm_table_get_mode(ti->table), &dev); + if (r) { + DMWARN("dm-multipath message: error getting device %s", + argv[1]); + return -EINVAL; + } + + r = action_dev(m, dev, action); + + dm_put_device(ti, dev); + + return r; + +error: + DMWARN("Unrecognised multipath message received."); + return -EINVAL; +} + +/*----------------------------------------------------------------- + * Module setup + *---------------------------------------------------------------*/ +static struct target_type multipath_target = { + .name = "multipath", + .version = {1, 0, 4}, + .module = THIS_MODULE, + .ctr = multipath_ctr, + .dtr = multipath_dtr, + .map = multipath_map, + .end_io = multipath_end_io, + .presuspend = multipath_presuspend, + .resume = multipath_resume, + .status = multipath_status, + .message = multipath_message, +}; + +static int __init dm_multipath_init(void) +{ + int r; + + /* allocate a slab for the dm_ios */ + _mpio_cache = kmem_cache_create("dm_mpath", sizeof(struct mpath_io), + 0, 0, NULL, NULL); + if (!_mpio_cache) + return -ENOMEM; + + r = dm_register_target(&multipath_target); + if (r < 0) { + DMERR("%s: register failed %d", multipath_target.name, r); + kmem_cache_destroy(_mpio_cache); + return -EINVAL; + } + + DMINFO("dm-multipath 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) +{ + int r; + + r = dm_unregister_target(&multipath_target); + if (r < 0) + DMERR("%s: target unregister failed %d", + multipath_target.name, r); + kmem_cache_destroy(_mpio_cache); +} + +EXPORT_SYMBOL_GPL(dm_pg_init_complete); + +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"); |