Merge git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm

* git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm:
  dm mpath: add missing path switching locking
  dm: cope with access beyond end of device in dm_merge_bvec
  dm: always allow one page in dm_merge_bvec

drivers/md/dm-mpath.c

@@ -63,6 +63,7 @@ struct multipath {
 
 	const char *hw_handler_name;
 	struct work_struct activate_path;
+	struct pgpath *pgpath_to_activate;
 	unsigned nr_priority_groups;
 	struct list_head priority_groups;
 	unsigned pg_init_required;	/* pg_init needs calling? */
@@ -146,6 +147,7 @@ static struct priority_group *alloc_priority_group(void)
 
 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
 {
+	unsigned long flags;
 	struct pgpath *pgpath, *tmp;
 	struct multipath *m = ti->private;
 
@@ -154,6 +156,10 @@ static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
 		if (m->hw_handler_name)
 			scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
 		dm_put_device(ti, pgpath->path.dev);
+		spin_lock_irqsave(&m->lock, flags);
+		if (m->pgpath_to_activate == pgpath)
+			m->pgpath_to_activate = NULL;
+		spin_unlock_irqrestore(&m->lock, flags);
 		free_pgpath(pgpath);
 	}
 }
@@ -421,6 +427,7 @@ static void process_queued_ios(struct work_struct *work)
 		__choose_pgpath(m);
 
 	pgpath = m->current_pgpath;
+	m->pgpath_to_activate = m->current_pgpath;
 
 	if ((pgpath && !m->queue_io) ||
 	    (!pgpath && !m->queue_if_no_path))
@@ -1093,8 +1100,15 @@ static void activate_path(struct work_struct *work)
 	int ret;
 	struct multipath *m =
 		container_of(work, struct multipath, activate_path);
-	struct dm_path *path = &m->current_pgpath->path;
+	struct dm_path *path;
+	unsigned long flags;
 
+	spin_lock_irqsave(&m->lock, flags);
+	path = &m->pgpath_to_activate->path;
+	m->pgpath_to_activate = NULL;
+	spin_unlock_irqrestore(&m->lock, flags);
+	if (!path)
+		return;
 	ret = scsi_dh_activate(bdev_get_queue(path->dev->bdev));
 	pg_init_done(path, ret);
 }

drivers/md/dm.c

@@ -837,12 +837,14 @@ static int dm_merge_bvec(struct request_queue *q,
 	struct dm_table *map = dm_get_table(md);
 	struct dm_target *ti;
 	sector_t max_sectors;
-	int max_size;
+	int max_size = 0;
 
 	if (unlikely(!map))
-		return 0;
+		goto out;
 
 	ti = dm_table_find_target(map, bvm->bi_sector);
+	if (!dm_target_is_valid(ti))
+		goto out_table;
 
 	/*
 	 * Find maximum amount of I/O that won't need splitting
@@ -861,14 +863,16 @@ static int dm_merge_bvec(struct request_queue *q,
 	if (max_size && ti->type->merge)
 		max_size = ti->type->merge(ti, bvm, biovec, max_size);
 
+out_table:
+	dm_table_put(map);
+
+out:
 	/*
 	 * Always allow an entire first page
 	 */
 	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
 		max_size = biovec->bv_len;
 
-	dm_table_put(map);
-
 	return max_size;
 }