1 files changed, 78 insertions, 93 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 2950b145443d..52cd3f1608b3 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -90,7 +90,7 @@ struct multipath {
 	atomic_t pg_init_in_progress;	/* Only one pg_init allowed at once */
 	atomic_t pg_init_count;		/* Number of times pg_init called */
 
-	unsigned queue_mode;
+	enum dm_queue_mode queue_mode;
 
 	struct mutex work_mutex;
 	struct work_struct trigger_event;
@@ -111,7 +111,8 @@ 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_path(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);
 
 /*-----------------------------------------------
@@ -136,7 +137,7 @@ static struct pgpath *alloc_pgpath(void)
 
 	if (pgpath) {
 		pgpath->is_active = true;
-		INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
+		INIT_DELAYED_WORK(&pgpath->activate_path, activate_path_work);
 	}
 
 	return pgpath;
@@ -297,6 +298,8 @@ 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;
 
@@ -321,13 +324,16 @@ static int __pg_init_all_paths(struct multipath *m)
 	return atomic_read(&m->pg_init_in_progress);
 }
 
-static void pg_init_all_paths(struct multipath *m)
+static int pg_init_all_paths(struct multipath *m)
 {
+	int ret;
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-	__pg_init_all_paths(m);
+	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)
@@ -436,45 +442,21 @@ failed:
 }
 
 /*
- * Check whether bios must be queued in the device-mapper core rather
- * than here in the target.
- *
- * 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.
+ * 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.
  */
-static bool __must_push_back(struct multipath *m)
-{
-	return ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) !=
-		 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) &&
-		dm_noflush_suspending(m->ti));
-}
-
-static bool must_push_back_rq(struct multipath *m)
-{
-	bool r;
-	unsigned long flags;
-
-	spin_lock_irqsave(&m->lock, flags);
-	r = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
-	     __must_push_back(m));
-	spin_unlock_irqrestore(&m->lock, flags);
-
-	return r;
-}
-
-static bool must_push_back_bio(struct multipath *m)
-{
-	bool r;
-	unsigned long flags;
-
-	spin_lock_irqsave(&m->lock, flags);
-	r = __must_push_back(m);
-	spin_unlock_irqrestore(&m->lock, flags);
-
-	return r;
-}
+#define dm_report_EIO(m)						\
+({									\
+	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));			\
+	-EIO;								\
+})
 
 /*
  * Map cloned requests (request-based multipath)
@@ -484,11 +466,11 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
 				   struct request **__clone)
 {
 	struct multipath *m = ti->private;
-	int r = DM_MAPIO_REQUEUE;
 	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? */
@@ -497,13 +479,14 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
 		pgpath = choose_pgpath(m, nr_bytes);
 
 	if (!pgpath) {
-		if (must_push_back_rq(m))
+		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
 			return DM_MAPIO_DELAY_REQUEUE;
-		return -EIO;	/* Failed */
+		return dm_report_EIO(m);	/* Failed */
 	} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
 		   test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
-		pg_init_all_paths(m);
-		return r;
+		if (pg_init_all_paths(m))
+			return DM_MAPIO_DELAY_REQUEUE;
+		return DM_MAPIO_REQUEUE;
 	}
 
 	memset(mpio, 0, sizeof(*mpio));
@@ -511,13 +494,19 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
 	mpio->nr_bytes = nr_bytes;
 
 	bdev = pgpath->path.dev->bdev;
-
-	clone = blk_get_request(bdev_get_queue(bdev),
-			rq->cmd_flags | REQ_NOMERGE,
-			GFP_ATOMIC);
+	q = bdev_get_queue(bdev);
+	clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE, GFP_ATOMIC);
 	if (IS_ERR(clone)) {
 		/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
-		return r;
+		bool queue_dying = blk_queue_dying(q);
+		DMERR_LIMIT("blk_get_request() returned %ld%s - requeuing",
+			    PTR_ERR(clone), queue_dying ? " (path offline)" : "");
+		if (queue_dying) {
+			atomic_inc(&m->pg_init_in_progress);
+			activate_or_offline_path(pgpath);
+			return DM_MAPIO_REQUEUE;
+		}
+		return DM_MAPIO_DELAY_REQUEUE;
 	}
 	clone->bio = clone->biotail = NULL;
 	clone->rq_disk = bdev->bd_disk;
@@ -567,9 +556,9 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
 	}
 
 	if (!pgpath) {
-		if (!must_push_back_bio(m))
-			return -EIO;
-		return DM_MAPIO_REQUEUE;
+		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
+			return DM_MAPIO_REQUEUE;
+		return dm_report_EIO(m);
 	}
 
 	mpio->pgpath = pgpath;
@@ -640,6 +629,14 @@ static void process_queued_bios(struct work_struct *work)
 	blk_finish_plug(&plug);
 }
 
+static void assign_bit(bool value, long nr, unsigned long *addr)
+{
+	if (value)
+		set_bit(nr, addr);
+	else
+		clear_bit(nr, addr);
+}
+
 /*
  * If we run out of usable paths, should we queue I/O or error it?
  */
@@ -649,23 +646,11 @@ static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-
-	if (save_old_value) {
-		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
-			set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
-		else
-			clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
-	} else {
-		if (queue_if_no_path)
-			set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
-		else
-			clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
-	}
-	if (queue_if_no_path)
-		set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
-	else
-		clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
-
+	assign_bit((save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
+		   (!save_old_value && queue_if_no_path),
+		   MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
+	assign_bit(queue_if_no_path || dm_noflush_suspending(m->ti),
+		   MPATHF_QUEUE_IF_NO_PATH, &m->flags);
 	spin_unlock_irqrestore(&m->lock, flags);
 
 	if (!queue_if_no_path) {
@@ -1438,10 +1423,8 @@ out:
 	spin_unlock_irqrestore(&m->lock, flags);
 }
 
-static void activate_path(struct work_struct *work)
+static void activate_or_offline_path(struct pgpath *pgpath)
 {
-	struct pgpath *pgpath =
-		container_of(work, struct pgpath, activate_path.work);
 	struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
 
 	if (pgpath->is_active && !blk_queue_dying(q))
@@ -1450,6 +1433,14 @@ static void activate_path(struct work_struct *work)
 		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 noretry_error(int error)
 {
 	switch (error) {
@@ -1501,12 +1492,9 @@ static int do_end_io(struct multipath *m, struct request *clone,
 	if (mpio->pgpath)
 		fail_path(mpio->pgpath);
 
-	if (!atomic_read(&m->nr_valid_paths)) {
-		if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
-			if (!must_push_back_rq(m))
-				r = -EIO;
-		}
-	}
+	if (atomic_read(&m->nr_valid_paths) == 0 &&
+	    !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
+		r = dm_report_EIO(m);
 
 	return r;
 }
@@ -1547,13 +1535,9 @@ static int do_end_io_bio(struct multipath *m, struct bio *clone,
 	if (mpio->pgpath)
 		fail_path(mpio->pgpath);
 
-	if (!atomic_read(&m->nr_valid_paths)) {
-		if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
-			if (!must_push_back_bio(m))
-				return -EIO;
-			return DM_ENDIO_REQUEUE;
-		}
-	}
+	if (atomic_read(&m->nr_valid_paths) == 0 &&
+	    !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
+		return dm_report_EIO(m);
 
 	/* Queue for the daemon to resubmit */
 	dm_bio_restore(get_bio_details_from_bio(clone), clone);
@@ -1619,10 +1603,8 @@ static void multipath_resume(struct dm_target *ti)
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-	if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags))
-		set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
-	else
-		clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
+	assign_bit(test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
+		   MPATHF_QUEUE_IF_NO_PATH, &m->flags);
 	spin_unlock_irqrestore(&m->lock, flags);
 }
 
@@ -1682,6 +1664,9 @@ static void multipath_status(struct dm_target *ti, status_type_t type,
 			case DM_TYPE_MQ_REQUEST_BASED:
 				DMEMIT("queue_mode mq ");
 				break;
+			default:
+				WARN_ON_ONCE(true);
+				break;
 			}
 		}
 	}