dm: handle failures in dm_table_set_restrictions

If dm_table_set_restrictions() fails while swapping tables,
device-mapper will continue using the previous table. It must be sure to
leave the mapped_device in it's previous state on failure.  Otherwise
device-mapper could end up using the old table with settings from the
unused table.

Do not update the mapped device in dm_set_zones_restrictions(). Wait
till after dm_table_set_restrictions() is sure to succeed to update the
md zoned settings. Do the same with the dax settings, and if
dm_revalidate_zones() fails, restore the original queue limits.

Fixes: 7f91ccd ("dm: Call dm_revalidate_zones() after setting the queue limits")
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Author: bmarzins

drivers/md/dm-table.c

@@ -1835,6 +1835,7 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 			      struct queue_limits *limits)
 {
 	int r;
+	struct queue_limits old_limits;
 
 	if (!dm_table_supports_nowait(t))
 		limits->features &= ~BLK_FEAT_NOWAIT;
@@ -1861,16 +1862,11 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	if (dm_table_supports_flush(t))
 		limits->features |= BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA;
 
-	if (dm_table_supports_dax(t, device_not_dax_capable)) {
+	if (dm_table_supports_dax(t, device_not_dax_capable))
 		limits->features |= BLK_FEAT_DAX;
-		if (dm_table_supports_dax(t, device_not_dax_synchronous_capable))
-			set_dax_synchronous(t->md->dax_dev);
-	} else
+	else
 		limits->features &= ~BLK_FEAT_DAX;
 
-	if (dm_table_any_dev_attr(t, device_dax_write_cache_enabled, NULL))
-		dax_write_cache(t->md->dax_dev, true);
-
 	/* For a zoned table, setup the zone related queue attributes. */
 	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
 	    (limits->features & BLK_FEAT_ZONED)) {
@@ -1882,7 +1878,8 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	if (dm_table_supports_atomic_writes(t))
 		limits->features |= BLK_FEAT_ATOMIC_WRITES;
 
-	r = queue_limits_set(q, limits);
+	old_limits = queue_limits_start_update(q);
+	r = queue_limits_commit_update(q, limits);
 	if (r)
 		return r;
 
@@ -1893,10 +1890,21 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
 	    (limits->features & BLK_FEAT_ZONED)) {
 		r = dm_revalidate_zones(t, q);
-		if (r)
+		if (r) {
+			queue_limits_set(q, &old_limits);
 			return r;
+		}
 	}
 
+	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED))
+		dm_finalize_zone_settings(t, limits);
+
+	if (dm_table_supports_dax(t, device_not_dax_synchronous_capable))
+		set_dax_synchronous(t->md->dax_dev);
+
+	if (dm_table_any_dev_attr(t, device_dax_write_cache_enabled, NULL))
+		dax_write_cache(t->md->dax_dev, true);
+
 	dm_update_crypto_profile(q, t);
 	return 0;
 }

drivers/md/dm-zone.c

@@ -340,12 +340,8 @@ int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
 	 * mapped device queue as needing zone append emulation.
 	 */
 	WARN_ON_ONCE(queue_is_mq(q));
-	if (dm_table_supports_zone_append(t)) {
-		clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
-	} else {
-		set_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
+	if (!dm_table_supports_zone_append(t))
 		lim->max_hw_zone_append_sectors = 0;
-	}
 
 	/*
 	 * Determine the max open and max active zone limits for the mapped
@@ -383,9 +379,6 @@ int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
 		lim->zone_write_granularity = 0;
 		lim->chunk_sectors = 0;
 		lim->features &= ~BLK_FEAT_ZONED;
-		clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
-		md->nr_zones = 0;
-		disk->nr_zones = 0;
 		return 0;
 	}
 
@@ -408,6 +401,23 @@ int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
 	return 0;
 }
 
+void dm_finalize_zone_settings(struct dm_table *t, struct queue_limits *lim)
+{
+	struct mapped_device *md = t->md;
+
+	if (lim->features & BLK_FEAT_ZONED) {
+		if (dm_table_supports_zone_append(t))
+			clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
+		else
+			set_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
+	} else {
+		clear_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
+		md->nr_zones = 0;
+		md->disk->nr_zones = 0;
+	}
+}
+
+
 /*
  * IO completion callback called from clone_endio().
  */

drivers/md/dm.h

@@ -102,6 +102,7 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t);
 int dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q,
 		struct queue_limits *lim);
 int dm_revalidate_zones(struct dm_table *t, struct request_queue *q);
+void dm_finalize_zone_settings(struct dm_table *t, struct queue_limits *lim);
 void dm_zone_endio(struct dm_io *io, struct bio *clone);
 #ifdef CONFIG_BLK_DEV_ZONED
 int dm_blk_report_zones(struct gendisk *disk, sector_t sector,