--- /dev/null
+/*
+ * 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.h"
+#include "dm-path-selector.h"
+#include "dm-uevent.h"
+
+#include <linux/blkdev.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_disabled:1; /* pg_init is not currently allowed */
+
+ 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 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);
+
+static struct kmem_cache *_mpio_cache;
+
+static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
+static void trigger_event(struct work_struct *work);
+static void activate_path(struct work_struct *work);
+static int __pgpath_busy(struct pgpath *pgpath);
+
+
+/*-----------------------------------------------
+ * 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;
+ unsigned min_ios = dm_get_reserved_rq_based_ios();
+
+ m = kzalloc(sizeof(*m), GFP_KERNEL);
+ if (m) {
+ INIT_LIST_HEAD(&m->priority_groups);
+ spin_lock_init(&m->lock);
+ m->queue_io = 1;
+ m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
+ 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 int __pg_init_all_paths(struct multipath *m)
+{
+ struct pgpath *pgpath;
+ unsigned long pg_init_delay = 0;
+
+ if (m->pg_init_in_progress || m->pg_init_disabled)
+ return 0;
+
+ m->pg_init_count++;
+ m->pg_init_required = 0;
+
+ /* Check here to reset pg_init_required */
+ if (!m->current_pg)
+ return 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++;
+ }
+ return 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) {
+ m->queue_io = 0;
+ 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->queue_if_no_path != m->saved_queue_if_no_path &&
+ dm_noflush_suspending(m->ti)));
+}
+
+/*
+ * Map cloned requests
+ */
+static int __multipath_map(struct dm_target *ti, struct request *clone,
+ union map_info *map_context,
+ struct request *rq, struct request **__clone)
+{
+ struct multipath *m = (struct multipath *) ti->private;
+ int r = DM_MAPIO_REQUEUE;
+ size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
+ struct pgpath *pgpath;
+ struct block_device *bdev;
+ struct dm_mpath_io *mpio;
+
+ spin_lock_irq(&m->lock);
+
+ /* 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 (!pgpath) {
+ if (!__must_push_back(m))
+ r = -EIO; /* Failed */
+ goto out_unlock;
+ } else if (m->queue_io || m->pg_init_required) {
+ __pg_init_all_paths(m);
+ goto out_unlock;
+ }
+
+ if (set_mapinfo(m, map_context) < 0)
+ /* ENOMEM, requeue */
+ goto out_unlock;
+
+ mpio = map_context->ptr;
+ mpio->pgpath = pgpath;
+ mpio->nr_bytes = nr_bytes;
+
+ bdev = pgpath->path.dev->bdev;
+
+ spin_unlock_irq(&m->lock);
+
+ if (clone) {
+ /* Old request-based interface: allocated clone is passed in */
+ clone->q = bdev_get_queue(bdev);
+ clone->rq_disk = bdev->bd_disk;
+ clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+ } else {
+ /* blk-mq request-based interface */
+ *__clone = blk_get_request(bdev_get_queue(bdev),
+ rq_data_dir(rq), GFP_ATOMIC);
+ if (IS_ERR(*__clone)) {
+ /* ENOMEM, requeue */
+ clear_mapinfo(m, map_context);
+ return r;
+ }
+ (*__clone)->bio = (*__clone)->biotail = NULL;
+ (*__clone)->rq_disk = bdev->bd_disk;
+ (*__clone)->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+ }
+
+ if (pgpath->pg->ps.type->start_io)
+ pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
+ &pgpath->path,
+ nr_bytes);
+ return DM_MAPIO_REMAPPED;
+
+out_unlock:
+ spin_unlock_irq(&m->lock);
+
+ return r;
+}
+
+static int multipath_map(struct dm_target *ti, struct request *clone,
+ union map_info *map_context)
+{
+ return __multipath_map(ti, clone, map_context, NULL, NULL);
+}
+
+static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
+ union map_info *map_context,
+ struct request **clone)
+{
+ return __multipath_map(ti, NULL, map_context, rq, clone);
+}
+
+static void multipath_release_clone(struct request *clone)
+{
+ blk_put_request(clone);
+}
+
+/*
+ * 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;
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ if (!queue_if_no_path)
+ dm_table_run_md_queue_async(m->ti->table);
+
+ return 0;
+}
+
+/*
+ * 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_bios = 1;
+ ti->num_discard_bios = 1;
+ ti->num_write_same_bios = 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)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&m->lock, flags);
+ m->pg_init_disabled = 1;
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ flush_workqueue(kmpath_handlerd);
+ multipath_wait_for_pg_init_completion(m);
+ flush_workqueue(kmultipathd);
+ flush_work(&m->trigger_event);
+
+ spin_lock_irqsave(&m->lock, flags);
+ m->pg_init_disabled = 0;
+ spin_unlock_irqrestore(&m->lock, flags);
+}
+
+static void multipath_dtr(struct dm_target *ti)
+{
+ struct multipath *m = ti->private;
+
+ flush_multipath_work(m);
+ free_multipath(m);
+}
+
+/*
+ * 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, run_queue = 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->current_pgpath = NULL;
+ run_queue = 1;
+ } 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);
+ if (run_queue)
+ dm_table_run_md_queue_async(m->ti->table);
+
+ 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_disabled)
+ 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->pg_init_delay_retry = delay_retry;
+ if (__pg_init_all_paths(m))
+ goto out;
+ }
+ m->queue_io = 0;
+
+ /*
+ * 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);
+
+ if (pgpath->is_active)
+ scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
+ pg_init_done, pgpath);
+ else
+ pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
+}
+
+static int noretry_error(int error)
+{
+ switch (error) {
+ case -EOPNOTSUPP:
+ case -EREMOTEIO:
+ case -EILSEQ:
+ case -ENODATA:
+ case -ENOSPC:
+ return 1;
+ }
+
+ /* Anything else could be a path failure, so should be retried */
+ return 0;
+}
+
+/*
+ * 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 (noretry_error(error))
+ 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 void 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_io, 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);
+}
+
+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("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
+ 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: %s", argv[0]);
+ 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;
+
+ 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 = -ENOTCONN;
+ else if (!bdev)
+ r = -EIO;
+
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ /*
+ * Only pass ioctls through if the device sizes match exactly.
+ */
+ if (!bdev || ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT) {
+ int err = scsi_verify_blk_ioctl(NULL, cmd);
+ if (err)
+ r = err;
+ }
+
+ if (r == -ENOTCONN && !fatal_signal_pending(current)) {
+ spin_lock_irqsave(&m->lock, flags);
+ if (!m->current_pg) {
+ /* Path status changed, redo selection */
+ __choose_pgpath(m, 0);
+ }
+ if (m->pg_init_required)
+ __pg_init_all_paths(m);
+ spin_unlock_irqrestore(&m->lock, flags);
+ dm_table_run_md_queue_async(m->ti->table);
+ }
+
+ 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 blk_lld_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);
+
+ /* pg_init in progress or no paths available */
+ if (m->pg_init_in_progress ||
+ (!m->nr_valid_paths && m->queue_if_no_path)) {
+ busy = 1;
+ goto out;
+ }
+ /* 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, 9, 0},
+ .module = THIS_MODULE,
+ .ctr = multipath_ctr,
+ .dtr = multipath_dtr,
+ .map_rq = multipath_map,
+ .clone_and_map_rq = multipath_clone_and_map,
+ .release_clone_rq = multipath_release_clone,
+ .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);
+ r = -EINVAL;
+ goto bad_register_target;
+ }
+
+ kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
+ if (!kmultipathd) {
+ DMERR("failed to create workqueue kmpathd");
+ r = -ENOMEM;
+ goto bad_alloc_kmultipathd;
+ }
+
+ /*
+ * 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");
+ r = -ENOMEM;
+ goto bad_alloc_kmpath_handlerd;
+ }
+
+ DMINFO("version %u.%u.%u loaded",
+ multipath_target.version[0], multipath_target.version[1],
+ multipath_target.version[2]);
+
+ return 0;
+
+bad_alloc_kmpath_handlerd:
+ destroy_workqueue(kmultipathd);
+bad_alloc_kmultipathd:
+ dm_unregister_target(&multipath_target);
+bad_register_target:
+ kmem_cache_destroy(_mpio_cache);
+
+ 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");
Code Review / kvmfornfv.git / blobdiff