v4.19.13 snapshot.
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
new file mode 100644
index 0000000..419362c
--- /dev/null
+++ b/drivers/md/dm-mpath.c
@@ -0,0 +1,2102 @@
+/*
+ * 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-rq.h"
+#include "dm-bio-record.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>
+#include <linux/blk-mq.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 fail_count; /* Cumulative failure count */
+
+ struct dm_path path;
+ struct delayed_work activate_path;
+
+ bool is_active:1; /* Path status */
+};
+
+#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 nr_pgpaths; /* Number of paths in PG */
+ struct list_head pgpaths;
+
+ bool bypassed:1; /* Temporarily bypass this PG? */
+};
+
+/* Multipath context */
+struct multipath {
+ unsigned long flags; /* Multipath state flags */
+
+ spinlock_t lock;
+ enum dm_queue_mode queue_mode;
+
+ struct pgpath *current_pgpath;
+ struct priority_group *current_pg;
+ struct priority_group *next_pg; /* Switch to this PG if set */
+
+ atomic_t nr_valid_paths; /* Total number of usable paths */
+ unsigned nr_priority_groups;
+ struct list_head priority_groups;
+
+ const char *hw_handler_name;
+ char *hw_handler_params;
+ wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
+ unsigned pg_init_retries; /* Number of times to retry pg_init */
+ unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
+ atomic_t pg_init_in_progress; /* Only one pg_init allowed at once */
+ atomic_t pg_init_count; /* Number of times pg_init called */
+
+ struct mutex work_mutex;
+ struct work_struct trigger_event;
+ struct dm_target *ti;
+
+ struct work_struct process_queued_bios;
+ struct bio_list queued_bios;
+};
+
+/*
+ * Context information attached to each io we process.
+ */
+struct dm_mpath_io {
+ struct pgpath *pgpath;
+ size_t nr_bytes;
+};
+
+typedef int (*action_fn) (struct pgpath *pgpath);
+
+static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
+static void trigger_event(struct work_struct *work);
+static void activate_or_offline_path(struct pgpath *pgpath);
+static void activate_path_work(struct work_struct *work);
+static void process_queued_bios(struct work_struct *work);
+
+/*-----------------------------------------------
+ * Multipath state flags.
+ *-----------------------------------------------*/
+
+#define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
+#define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
+#define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
+#define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
+#define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
+#define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
+#define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
+
+/*-----------------------------------------------
+ * Allocation routines
+ *-----------------------------------------------*/
+
+static struct pgpath *alloc_pgpath(void)
+{
+ struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
+
+ if (!pgpath)
+ return NULL;
+
+ pgpath->is_active = true;
+
+ 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;
+
+ 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(struct dm_target *ti)
+{
+ struct multipath *m;
+
+ m = kzalloc(sizeof(*m), GFP_KERNEL);
+ if (m) {
+ INIT_LIST_HEAD(&m->priority_groups);
+ spin_lock_init(&m->lock);
+ atomic_set(&m->nr_valid_paths, 0);
+ INIT_WORK(&m->trigger_event, trigger_event);
+ mutex_init(&m->work_mutex);
+
+ m->queue_mode = DM_TYPE_NONE;
+
+ m->ti = ti;
+ ti->private = m;
+ }
+
+ return m;
+}
+
+static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
+{
+ if (m->queue_mode == DM_TYPE_NONE) {
+ /*
+ * Default to request-based.
+ */
+ if (dm_use_blk_mq(dm_table_get_md(ti->table)))
+ m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
+ else
+ m->queue_mode = DM_TYPE_REQUEST_BASED;
+
+ } else if (m->queue_mode == DM_TYPE_BIO_BASED) {
+ INIT_WORK(&m->process_queued_bios, process_queued_bios);
+ /*
+ * bio-based doesn't support any direct scsi_dh management;
+ * it just discovers if a scsi_dh is attached.
+ */
+ set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
+ }
+
+ dm_table_set_type(ti->table, m->queue_mode);
+
+ /*
+ * Init fields that are only used when a scsi_dh is attached
+ * - must do this unconditionally (really doesn't hurt non-SCSI uses)
+ */
+ set_bit(MPATHF_QUEUE_IO, &m->flags);
+ atomic_set(&m->pg_init_in_progress, 0);
+ atomic_set(&m->pg_init_count, 0);
+ m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
+ init_waitqueue_head(&m->pg_init_wait);
+
+ return 0;
+}
+
+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);
+ mutex_destroy(&m->work_mutex);
+ kfree(m);
+}
+
+static struct dm_mpath_io *get_mpio(union map_info *info)
+{
+ return info->ptr;
+}
+
+static size_t multipath_per_bio_data_size(void)
+{
+ return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
+}
+
+static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
+{
+ return dm_per_bio_data(bio, multipath_per_bio_data_size());
+}
+
+static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
+{
+ /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
+ void *bio_details = mpio + 1;
+ return bio_details;
+}
+
+static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
+{
+ struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
+ struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
+
+ mpio->nr_bytes = bio->bi_iter.bi_size;
+ mpio->pgpath = NULL;
+ *mpio_p = mpio;
+
+ dm_bio_record(bio_details, bio);
+}
+
+/*-----------------------------------------------
+ * Path selection
+ *-----------------------------------------------*/
+
+static int __pg_init_all_paths(struct multipath *m)
+{
+ struct pgpath *pgpath;
+ unsigned long pg_init_delay = 0;
+
+ lockdep_assert_held(&m->lock);
+
+ if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
+ return 0;
+
+ atomic_inc(&m->pg_init_count);
+ clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
+
+ /* Check here to reset pg_init_required */
+ if (!m->current_pg)
+ return 0;
+
+ if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
+ 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))
+ atomic_inc(&m->pg_init_in_progress);
+ }
+ return atomic_read(&m->pg_init_in_progress);
+}
+
+static int pg_init_all_paths(struct multipath *m)
+{
+ int ret;
+ unsigned long flags;
+
+ spin_lock_irqsave(&m->lock, flags);
+ ret = __pg_init_all_paths(m);
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ return ret;
+}
+
+static void __switch_pg(struct multipath *m, struct priority_group *pg)
+{
+ m->current_pg = pg;
+
+ /* Must we initialise the PG first, and queue I/O till it's ready? */
+ if (m->hw_handler_name) {
+ set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
+ set_bit(MPATHF_QUEUE_IO, &m->flags);
+ } else {
+ clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
+ clear_bit(MPATHF_QUEUE_IO, &m->flags);
+ }
+
+ atomic_set(&m->pg_init_count, 0);
+}
+
+static struct pgpath *choose_path_in_pg(struct multipath *m,
+ struct priority_group *pg,
+ size_t nr_bytes)
+{
+ unsigned long flags;
+ struct dm_path *path;
+ struct pgpath *pgpath;
+
+ path = pg->ps.type->select_path(&pg->ps, nr_bytes);
+ if (!path)
+ return ERR_PTR(-ENXIO);
+
+ pgpath = path_to_pgpath(path);
+
+ if (unlikely(READ_ONCE(m->current_pg) != pg)) {
+ /* Only update current_pgpath if pg changed */
+ spin_lock_irqsave(&m->lock, flags);
+ m->current_pgpath = pgpath;
+ __switch_pg(m, pg);
+ spin_unlock_irqrestore(&m->lock, flags);
+ }
+
+ return pgpath;
+}
+
+static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
+{
+ unsigned long flags;
+ struct priority_group *pg;
+ struct pgpath *pgpath;
+ unsigned bypassed = 1;
+
+ if (!atomic_read(&m->nr_valid_paths)) {
+ clear_bit(MPATHF_QUEUE_IO, &m->flags);
+ goto failed;
+ }
+
+ /* Were we instructed to switch PG? */
+ if (READ_ONCE(m->next_pg)) {
+ spin_lock_irqsave(&m->lock, flags);
+ pg = m->next_pg;
+ if (!pg) {
+ spin_unlock_irqrestore(&m->lock, flags);
+ goto check_current_pg;
+ }
+ m->next_pg = NULL;
+ spin_unlock_irqrestore(&m->lock, flags);
+ pgpath = choose_path_in_pg(m, pg, nr_bytes);
+ if (!IS_ERR_OR_NULL(pgpath))
+ return pgpath;
+ }
+
+ /* Don't change PG until it has no remaining paths */
+check_current_pg:
+ pg = READ_ONCE(m->current_pg);
+ if (pg) {
+ pgpath = choose_path_in_pg(m, pg, nr_bytes);
+ if (!IS_ERR_OR_NULL(pgpath))
+ return pgpath;
+ }
+
+ /*
+ * 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;
+ pgpath = choose_path_in_pg(m, pg, nr_bytes);
+ if (!IS_ERR_OR_NULL(pgpath)) {
+ if (!bypassed)
+ set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
+ return pgpath;
+ }
+ }
+ } while (bypassed--);
+
+failed:
+ spin_lock_irqsave(&m->lock, flags);
+ m->current_pgpath = NULL;
+ m->current_pg = NULL;
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ return NULL;
+}
+
+/*
+ * dm_report_EIO() is a macro instead of a function to make pr_debug()
+ * report the function name and line number of the function from which
+ * it has been invoked.
+ */
+#define dm_report_EIO(m) \
+do { \
+ struct mapped_device *md = dm_table_get_md((m)->ti->table); \
+ \
+ pr_debug("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d\n", \
+ dm_device_name(md), \
+ test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags), \
+ test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
+ dm_noflush_suspending((m)->ti)); \
+} while (0)
+
+/*
+ * Check whether bios must be queued in the device-mapper core rather
+ * than here in the target.
+ *
+ * If MPATHF_QUEUE_IF_NO_PATH and MPATHF_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 bool __must_push_back(struct multipath *m, unsigned long flags)
+{
+ return ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) !=
+ test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &flags)) &&
+ dm_noflush_suspending(m->ti));
+}
+
+/*
+ * Following functions use READ_ONCE to get atomic access to
+ * all m->flags to avoid taking spinlock
+ */
+static bool must_push_back_rq(struct multipath *m)
+{
+ unsigned long flags = READ_ONCE(m->flags);
+ return test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) || __must_push_back(m, flags);
+}
+
+static bool must_push_back_bio(struct multipath *m)
+{
+ unsigned long flags = READ_ONCE(m->flags);
+ return __must_push_back(m, flags);
+}
+
+/*
+ * Map cloned requests (request-based multipath)
+ */
+static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
+ union map_info *map_context,
+ struct request **__clone)
+{
+ struct multipath *m = ti->private;
+ size_t nr_bytes = blk_rq_bytes(rq);
+ struct pgpath *pgpath;
+ struct block_device *bdev;
+ struct dm_mpath_io *mpio = get_mpio(map_context);
+ struct request_queue *q;
+ struct request *clone;
+
+ /* Do we need to select a new pgpath? */
+ pgpath = READ_ONCE(m->current_pgpath);
+ if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
+ pgpath = choose_pgpath(m, nr_bytes);
+
+ if (!pgpath) {
+ if (must_push_back_rq(m))
+ return DM_MAPIO_DELAY_REQUEUE;
+ dm_report_EIO(m); /* Failed */
+ return DM_MAPIO_KILL;
+ } else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
+ test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
+ pg_init_all_paths(m);
+ return DM_MAPIO_DELAY_REQUEUE;
+ }
+
+ mpio->pgpath = pgpath;
+ mpio->nr_bytes = nr_bytes;
+
+ bdev = pgpath->path.dev->bdev;
+ q = bdev_get_queue(bdev);
+ clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE,
+ BLK_MQ_REQ_NOWAIT);
+ if (IS_ERR(clone)) {
+ /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
+ if (blk_queue_dying(q)) {
+ atomic_inc(&m->pg_init_in_progress);
+ activate_or_offline_path(pgpath);
+ return DM_MAPIO_DELAY_REQUEUE;
+ }
+
+ /*
+ * blk-mq's SCHED_RESTART can cover this requeue, so we
+ * needn't deal with it by DELAY_REQUEUE. More importantly,
+ * we have to return DM_MAPIO_REQUEUE so that blk-mq can
+ * get the queue busy feedback (via BLK_STS_RESOURCE),
+ * otherwise I/O merging can suffer.
+ */
+ if (q->mq_ops)
+ return DM_MAPIO_REQUEUE;
+ else
+ return DM_MAPIO_DELAY_REQUEUE;
+ }
+ clone->bio = clone->biotail = NULL;
+ clone->rq_disk = bdev->bd_disk;
+ clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+ *__clone = clone;
+
+ if (pgpath->pg->ps.type->start_io)
+ pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
+ &pgpath->path,
+ nr_bytes);
+ return DM_MAPIO_REMAPPED;
+}
+
+static void multipath_release_clone(struct request *clone)
+{
+ blk_put_request(clone);
+}
+
+/*
+ * Map cloned bios (bio-based multipath)
+ */
+
+static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
+{
+ struct pgpath *pgpath;
+ unsigned long flags;
+ bool queue_io;
+
+ /* Do we need to select a new pgpath? */
+ pgpath = READ_ONCE(m->current_pgpath);
+ queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
+ if (!pgpath || !queue_io)
+ pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
+
+ if ((pgpath && queue_io) ||
+ (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
+ /* Queue for the daemon to resubmit */
+ spin_lock_irqsave(&m->lock, flags);
+ bio_list_add(&m->queued_bios, bio);
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
+ if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
+ pg_init_all_paths(m);
+ else if (!queue_io)
+ queue_work(kmultipathd, &m->process_queued_bios);
+
+ return ERR_PTR(-EAGAIN);
+ }
+
+ return pgpath;
+}
+
+static struct pgpath *__map_bio_fast(struct multipath *m, struct bio *bio)
+{
+ struct pgpath *pgpath;
+ unsigned long flags;
+
+ /* Do we need to select a new pgpath? */
+ /*
+ * FIXME: currently only switching path if no path (due to failure, etc)
+ * - which negates the point of using a path selector
+ */
+ pgpath = READ_ONCE(m->current_pgpath);
+ if (!pgpath)
+ pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
+
+ if (!pgpath) {
+ if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
+ /* Queue for the daemon to resubmit */
+ spin_lock_irqsave(&m->lock, flags);
+ bio_list_add(&m->queued_bios, bio);
+ spin_unlock_irqrestore(&m->lock, flags);
+ queue_work(kmultipathd, &m->process_queued_bios);
+
+ return ERR_PTR(-EAGAIN);
+ }
+ return NULL;
+ }
+
+ return pgpath;
+}
+
+static int __multipath_map_bio(struct multipath *m, struct bio *bio,
+ struct dm_mpath_io *mpio)
+{
+ struct pgpath *pgpath;
+
+ if (!m->hw_handler_name)
+ pgpath = __map_bio_fast(m, bio);
+ else
+ pgpath = __map_bio(m, bio);
+
+ if (IS_ERR(pgpath))
+ return DM_MAPIO_SUBMITTED;
+
+ if (!pgpath) {
+ if (must_push_back_bio(m))
+ return DM_MAPIO_REQUEUE;
+ dm_report_EIO(m);
+ return DM_MAPIO_KILL;
+ }
+
+ mpio->pgpath = pgpath;
+
+ bio->bi_status = 0;
+ bio_set_dev(bio, pgpath->path.dev->bdev);
+ bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
+
+ if (pgpath->pg->ps.type->start_io)
+ pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
+ &pgpath->path,
+ mpio->nr_bytes);
+ return DM_MAPIO_REMAPPED;
+}
+
+static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
+{
+ struct multipath *m = ti->private;
+ struct dm_mpath_io *mpio = NULL;
+
+ multipath_init_per_bio_data(bio, &mpio);
+ return __multipath_map_bio(m, bio, mpio);
+}
+
+static void process_queued_io_list(struct multipath *m)
+{
+ if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
+ dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
+ else if (m->queue_mode == DM_TYPE_BIO_BASED)
+ queue_work(kmultipathd, &m->process_queued_bios);
+}
+
+static void process_queued_bios(struct work_struct *work)
+{
+ int r;
+ unsigned long flags;
+ struct bio *bio;
+ struct bio_list bios;
+ struct blk_plug plug;
+ struct multipath *m =
+ container_of(work, struct multipath, process_queued_bios);
+
+ bio_list_init(&bios);
+
+ spin_lock_irqsave(&m->lock, flags);
+
+ if (bio_list_empty(&m->queued_bios)) {
+ spin_unlock_irqrestore(&m->lock, flags);
+ return;
+ }
+
+ bio_list_merge(&bios, &m->queued_bios);
+ bio_list_init(&m->queued_bios);
+
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ blk_start_plug(&plug);
+ while ((bio = bio_list_pop(&bios))) {
+ struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
+ dm_bio_restore(get_bio_details_from_mpio(mpio), bio);
+ r = __multipath_map_bio(m, bio, mpio);
+ switch (r) {
+ case DM_MAPIO_KILL:
+ bio->bi_status = BLK_STS_IOERR;
+ bio_endio(bio);
+ break;
+ case DM_MAPIO_REQUEUE:
+ bio->bi_status = BLK_STS_DM_REQUEUE;
+ bio_endio(bio);
+ break;
+ case DM_MAPIO_REMAPPED:
+ generic_make_request(bio);
+ break;
+ case DM_MAPIO_SUBMITTED:
+ break;
+ default:
+ WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
+ }
+ }
+ blk_finish_plug(&plug);
+}
+
+/*
+ * If we run out of usable paths, should we queue I/O or error it?
+ */
+static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
+ bool save_old_value)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&m->lock, flags);
+ assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags,
+ (save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
+ (!save_old_value && queue_if_no_path));
+ assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path);
+ spin_unlock_irqrestore(&m->lock, flags);
+
+ if (!queue_if_no_path) {
+ dm_table_run_md_queue_async(m->ti->table);
+ process_queued_io_list(m);
+ }
+
+ 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 const 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 int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
+ const char **attached_handler_name, char **error)
+{
+ struct request_queue *q = bdev_get_queue(bdev);
+ int r;
+
+ if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
+retain:
+ if (*attached_handler_name) {
+ /*
+ * Clear any hw_handler_params associated with a
+ * handler that isn't already attached.
+ */
+ if (m->hw_handler_name && strcmp(*attached_handler_name, m->hw_handler_name)) {
+ kfree(m->hw_handler_params);
+ m->hw_handler_params = NULL;
+ }
+
+ /*
+ * Reset hw_handler_name to match the attached 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;
+ *attached_handler_name = NULL;
+ }
+ }
+
+ if (m->hw_handler_name) {
+ r = scsi_dh_attach(q, m->hw_handler_name);
+ if (r == -EBUSY) {
+ char b[BDEVNAME_SIZE];
+
+ printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
+ bdevname(bdev, b));
+ goto retain;
+ }
+ if (r < 0) {
+ *error = "error attaching hardware handler";
+ return r;
+ }
+
+ if (m->hw_handler_params) {
+ r = scsi_dh_set_params(q, m->hw_handler_params);
+ if (r < 0) {
+ *error = "unable to set hardware handler parameters";
+ return r;
+ }
+ }
+ }
+
+ 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;
+ const char *attached_handler_name = NULL;
+
+ /* 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;
+ }
+
+ q = bdev_get_queue(p->path.dev->bdev);
+ attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
+ if (attached_handler_name || m->hw_handler_name) {
+ INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
+ r = setup_scsi_dh(p->path.dev->bdev, m, &attached_handler_name, &ti->error);
+ if (r) {
+ 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:
+ kfree(attached_handler_name);
+ free_pgpath(p);
+ return ERR_PTR(r);
+}
+
+static struct priority_group *parse_priority_group(struct dm_arg_set *as,
+ struct multipath *m)
+{
+ static const 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 const 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;
+
+ if (m->queue_mode == DM_TYPE_BIO_BASED) {
+ dm_consume_args(as, hw_argc);
+ DMERR("bio-based multipath doesn't allow hardware handler args");
+ return 0;
+ }
+
+ m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
+ if (!m->hw_handler_name)
+ return -EINVAL;
+
+ 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 const struct dm_arg _args[] = {
+ {0, 8, "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, true, false);
+ continue;
+ }
+
+ if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
+ set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
+ 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;
+ }
+
+ if (!strcasecmp(arg_name, "queue_mode") &&
+ (argc >= 1)) {
+ const char *queue_mode_name = dm_shift_arg(as);
+
+ if (!strcasecmp(queue_mode_name, "bio"))
+ m->queue_mode = DM_TYPE_BIO_BASED;
+ else if (!strcasecmp(queue_mode_name, "rq"))
+ m->queue_mode = DM_TYPE_REQUEST_BASED;
+ else if (!strcasecmp(queue_mode_name, "mq"))
+ m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
+ else {
+ ti->error = "Unknown 'queue_mode' requested";
+ r = -EINVAL;
+ }
+ argc--;
+ continue;
+ }
+
+ ti->error = "Unrecognised multipath feature request";
+ r = -EINVAL;
+ } while (argc && !r);
+
+ return r;
+}
+
+static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
+{
+ /* target arguments */
+ static const 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 = alloc_multipath_stage2(ti, 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;
+ unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
+
+ pg = parse_priority_group(&as, m);
+ if (IS_ERR(pg)) {
+ r = PTR_ERR(pg);
+ goto bad;
+ }
+
+ nr_valid_paths += pg->nr_pgpaths;
+ atomic_set(&m->nr_valid_paths, nr_valid_paths);
+
+ 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;
+ ti->num_write_zeroes_bios = 1;
+ if (m->queue_mode == DM_TYPE_BIO_BASED)
+ ti->per_io_data_size = multipath_per_bio_data_size();
+ else
+ ti->per_io_data_size = sizeof(struct dm_mpath_io);
+
+ return 0;
+
+ bad:
+ free_multipath(m);
+ return r;
+}
+
+static void multipath_wait_for_pg_init_completion(struct multipath *m)
+{
+ DEFINE_WAIT(wait);
+
+ while (1) {
+ prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
+
+ if (!atomic_read(&m->pg_init_in_progress))
+ break;
+
+ io_schedule();
+ }
+ finish_wait(&m->pg_init_wait, &wait);
+}
+
+static void flush_multipath_work(struct multipath *m)
+{
+ if (m->hw_handler_name) {
+ set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
+ smp_mb__after_atomic();
+
+ flush_workqueue(kmpath_handlerd);
+ multipath_wait_for_pg_init_completion(m);
+
+ clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
+ smp_mb__after_atomic();
+ }
+
+ flush_workqueue(kmultipathd);
+ flush_work(&m->trigger_event);
+}
+
+static void multipath_dtr(struct dm_target *ti)
+{
+ struct multipath *m = ti->private;
+
+ flush_multipath_work(m);
+ free_multipath(m);
+}
+
+/*
+ * 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 = false;
+ pgpath->fail_count++;
+
+ atomic_dec(&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, atomic_read(&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;
+ unsigned nr_valid_paths;
+
+ spin_lock_irqsave(&m->lock, flags);
+
+ if (pgpath->is_active)
+ goto out;
+
+ DMWARN("Reinstating path %s.", pgpath->path.dev->name);
+
+ r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
+ if (r)
+ goto out;
+
+ pgpath->is_active = true;
+
+ nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
+ if (nr_valid_paths == 1) {
+ 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))
+ atomic_inc(&m->pg_init_in_progress);
+ }
+
+ dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
+ pgpath->path.dev->name, 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);
+ process_queued_io_list(m);
+ }
+
+ 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,
+ bool 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 ||
+ !m->nr_priority_groups || (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 = false;
+ 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, bool bypassed)
+{
+ struct priority_group *pg;
+ unsigned pgnum;
+ char dummy;
+
+ if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
+ !m->nr_priority_groups || (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 bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
+{
+ unsigned long flags;
+ bool limit_reached = false;
+
+ spin_lock_irqsave(&m->lock, flags);
+
+ if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
+ !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
+ set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
+ else
+ limit_reached = true;
+
+ 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;
+ bool delay_retry = false;
+
+ /* 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, true);
+ break;
+ case SCSI_DH_RETRY:
+ /* Wait before retrying. */
+ delay_retry = 1;
+ /* fall through */
+ case SCSI_DH_IMM_RETRY:
+ case SCSI_DH_RES_TEMP_UNAVAIL:
+ if (pg_init_limit_reached(m, pgpath))
+ fail_path(pgpath);
+ errors = 0;
+ break;
+ case SCSI_DH_DEV_OFFLINED:
+ 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 (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
+ pg->bypassed = false;
+
+ if (atomic_dec_return(&m->pg_init_in_progress) > 0)
+ /* Activations of other paths are still on going */
+ goto out;
+
+ if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
+ if (delay_retry)
+ set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
+ else
+ clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
+
+ if (__pg_init_all_paths(m))
+ goto out;
+ }
+ clear_bit(MPATHF_QUEUE_IO, &m->flags);
+
+ process_queued_io_list(m);
+
+ /*
+ * Wake up any thread waiting to suspend.
+ */
+ wake_up(&m->pg_init_wait);
+
+out:
+ spin_unlock_irqrestore(&m->lock, flags);
+}
+
+static void activate_or_offline_path(struct pgpath *pgpath)
+{
+ struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
+
+ if (pgpath->is_active && !blk_queue_dying(q))
+ scsi_dh_activate(q, pg_init_done, pgpath);
+ else
+ pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
+}
+
+static void activate_path_work(struct work_struct *work)
+{
+ struct pgpath *pgpath =
+ container_of(work, struct pgpath, activate_path.work);
+
+ activate_or_offline_path(pgpath);
+}
+
+static int multipath_end_io(struct dm_target *ti, struct request *clone,
+ blk_status_t error, union map_info *map_context)
+{
+ struct dm_mpath_io *mpio = get_mpio(map_context);
+ struct pgpath *pgpath = mpio->pgpath;
+ int r = DM_ENDIO_DONE;
+
+ /*
+ * 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-rq.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.
+ */
+ if (error && blk_path_error(error)) {
+ struct multipath *m = ti->private;
+
+ if (error == BLK_STS_RESOURCE)
+ r = DM_ENDIO_DELAY_REQUEUE;
+ else
+ r = DM_ENDIO_REQUEUE;
+
+ if (pgpath)
+ fail_path(pgpath);
+
+ if (atomic_read(&m->nr_valid_paths) == 0 &&
+ !must_push_back_rq(m)) {
+ if (error == BLK_STS_IOERR)
+ dm_report_EIO(m);
+ /* complete with the original error */
+ r = DM_ENDIO_DONE;
+ }
+ }
+
+ if (pgpath) {
+ struct path_selector *ps = &pgpath->pg->ps;
+
+ if (ps->type->end_io)
+ ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
+ }
+
+ return r;
+}
+
+static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
+ blk_status_t *error)
+{
+ struct multipath *m = ti->private;
+ struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
+ struct pgpath *pgpath = mpio->pgpath;
+ unsigned long flags;
+ int r = DM_ENDIO_DONE;
+
+ if (!*error || !blk_path_error(*error))
+ goto done;
+
+ if (pgpath)
+ fail_path(pgpath);
+
+ if (atomic_read(&m->nr_valid_paths) == 0 &&
+ !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
+ if (must_push_back_bio(m)) {
+ r = DM_ENDIO_REQUEUE;
+ } else {
+ dm_report_EIO(m);
+ *error = BLK_STS_IOERR;
+ }
+ goto done;
+ }
+
+ spin_lock_irqsave(&m->lock, flags);
+ bio_list_add(&m->queued_bios, clone);
+ spin_unlock_irqrestore(&m->lock, flags);
+ if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
+ queue_work(kmultipathd, &m->process_queued_bios);
+
+ r = DM_ENDIO_INCOMPLETE;
+done:
+ if (pgpath) {
+ struct path_selector *ps = &pgpath->pg->ps;
+
+ if (ps->type->end_io)
+ ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
+ }
+
+ 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 = ti->private;
+
+ queue_if_no_path(m, false, true);
+}
+
+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 = ti->private;
+ unsigned long flags;
+
+ spin_lock_irqsave(&m->lock, flags);
+ assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags,
+ test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
+ 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 = 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 ", test_bit(MPATHF_QUEUE_IO, &m->flags),
+ atomic_read(&m->pg_init_count));
+ else {
+ DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
+ (m->pg_init_retries > 0) * 2 +
+ (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
+ test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
+ (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
+
+ if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
+ 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 (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
+ DMEMIT("retain_attached_hw_handler ");
+ if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
+ switch(m->queue_mode) {
+ case DM_TYPE_BIO_BASED:
+ DMEMIT("queue_mode bio ");
+ break;
+ case DM_TYPE_MQ_REQUEST_BASED:
+ DMEMIT("queue_mode mq ");
+ break;
+ default:
+ WARN_ON_ONCE(true);
+ break;
+ }
+ }
+ }
+
+ 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,
+ char *result, unsigned maxlen)
+{
+ int r = -EINVAL;
+ struct dm_dev *dev;
+ struct multipath *m = 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, true, false);
+ goto out;
+ } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
+ r = queue_if_no_path(m, false, false);
+ 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], true);
+ goto out;
+ } else if (!strcasecmp(argv[0], "enable_group")) {
+ r = bypass_pg_num(m, argv[1], false);
+ 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_prepare_ioctl(struct dm_target *ti,
+ struct block_device **bdev)
+{
+ struct multipath *m = ti->private;
+ struct pgpath *current_pgpath;
+ int r;
+
+ current_pgpath = READ_ONCE(m->current_pgpath);
+ if (!current_pgpath)
+ current_pgpath = choose_pgpath(m, 0);
+
+ if (current_pgpath) {
+ if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
+ *bdev = current_pgpath->path.dev->bdev;
+ r = 0;
+ } else {
+ /* pg_init has not started or completed */
+ r = -ENOTCONN;
+ }
+ } else {
+ /* No path is available */
+ if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
+ r = -ENOTCONN;
+ else
+ r = -EIO;
+ }
+
+ if (r == -ENOTCONN) {
+ if (!READ_ONCE(m->current_pg)) {
+ /* Path status changed, redo selection */
+ (void) choose_pgpath(m, 0);
+ }
+ if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
+ pg_init_all_paths(m);
+ dm_table_run_md_queue_async(m->ti->table);
+ process_queued_io_list(m);
+ }
+
+ /*
+ * Only pass ioctls through if the device sizes match exactly.
+ */
+ if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
+ return 1;
+ return r;
+}
+
+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)
+{
+ bool busy = false, has_active = false;
+ struct multipath *m = ti->private;
+ struct priority_group *pg, *next_pg;
+ struct pgpath *pgpath;
+
+ /* pg_init in progress */
+ if (atomic_read(&m->pg_init_in_progress))
+ return true;
+
+ /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
+ if (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
+ return (m->queue_mode != DM_TYPE_MQ_REQUEST_BASED);
+
+ /* Guess which priority_group will be used at next mapping time */
+ pg = READ_ONCE(m->current_pg);
+ next_pg = READ_ONCE(m->next_pg);
+ if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
+ pg = next_pg;
+
+ if (!pg) {
+ /*
+ * 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.
+ */
+ return busy;
+ }
+
+ /*
+ * 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 = true;
+ list_for_each_entry(pgpath, &pg->pgpaths, list) {
+ if (pgpath->is_active) {
+ has_active = true;
+ if (!pgpath_busy(pgpath)) {
+ busy = false;
+ 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 = false;
+ }
+
+ return busy;
+}
+
+/*-----------------------------------------------------------------
+ * Module setup
+ *---------------------------------------------------------------*/
+static struct target_type multipath_target = {
+ .name = "multipath",
+ .version = {1, 13, 0},
+ .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE |
+ DM_TARGET_PASSES_INTEGRITY,
+ .module = THIS_MODULE,
+ .ctr = multipath_ctr,
+ .dtr = multipath_dtr,
+ .clone_and_map_rq = multipath_clone_and_map,
+ .release_clone_rq = multipath_release_clone,
+ .rq_end_io = multipath_end_io,
+ .map = multipath_map_bio,
+ .end_io = multipath_end_io_bio,
+ .presuspend = multipath_presuspend,
+ .postsuspend = multipath_postsuspend,
+ .resume = multipath_resume,
+ .status = multipath_status,
+ .message = multipath_message,
+ .prepare_ioctl = multipath_prepare_ioctl,
+ .iterate_devices = multipath_iterate_devices,
+ .busy = multipath_busy,
+};
+
+static int __init dm_multipath_init(void)
+{
+ int r;
+
+ 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;
+ }
+
+ r = dm_register_target(&multipath_target);
+ if (r < 0) {
+ DMERR("request-based register failed %d", r);
+ r = -EINVAL;
+ goto bad_register_target;
+ }
+
+ return 0;
+
+bad_register_target:
+ destroy_workqueue(kmpath_handlerd);
+bad_alloc_kmpath_handlerd:
+ destroy_workqueue(kmultipathd);
+bad_alloc_kmultipathd:
+ return r;
+}
+
+static void __exit dm_multipath_exit(void)
+{
+ destroy_workqueue(kmpath_handlerd);
+ destroy_workqueue(kmultipathd);
+
+ dm_unregister_target(&multipath_target);
+}
+
+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");