1 files changed, 39 insertions, 13 deletions

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 4b1be754cc41..cde3b49b2a91 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1698,14 +1698,6 @@ static int device_is_not_random(struct dm_target *ti, struct dm_dev *dev,
 	return q && !blk_queue_add_random(q);
 }
 
-static int queue_supports_sg_merge(struct dm_target *ti, struct dm_dev *dev,
-				   sector_t start, sector_t len, void *data)
-{
-	struct request_queue *q = bdev_get_queue(dev->bdev);
-
-	return q && !test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags);
-}
-
 static bool dm_table_all_devices_attribute(struct dm_table *t,
 					   iterate_devices_callout_fn func)
 {
@@ -1852,6 +1844,36 @@ static bool dm_table_supports_secure_erase(struct dm_table *t)
 	return true;
 }
 
+static int device_requires_stable_pages(struct dm_target *ti,
+					struct dm_dev *dev, sector_t start,
+					sector_t len, void *data)
+{
+	struct request_queue *q = bdev_get_queue(dev->bdev);
+
+	return q && bdi_cap_stable_pages_required(q->backing_dev_info);
+}
+
+/*
+ * If any underlying device requires stable pages, a table must require
+ * them as well.  Only targets that support iterate_devices are considered:
+ * don't want error, zero, etc to require stable pages.
+ */
+static bool dm_table_requires_stable_pages(struct dm_table *t)
+{
+	struct dm_target *ti;
+	unsigned i;
+
+	for (i = 0; i < dm_table_get_num_targets(t); i++) {
+		ti = dm_table_get_target(t, i);
+
+		if (ti->type->iterate_devices &&
+		    ti->type->iterate_devices(ti, device_requires_stable_pages, NULL))
+			return true;
+	}
+
+	return false;
+}
+
 void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 			       struct queue_limits *limits)
 {
@@ -1902,14 +1924,18 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	if (!dm_table_supports_write_zeroes(t))
 		q->limits.max_write_zeroes_sectors = 0;
 
-	if (dm_table_all_devices_attribute(t, queue_supports_sg_merge))
-		blk_queue_flag_clear(QUEUE_FLAG_NO_SG_MERGE, q);
-	else
-		blk_queue_flag_set(QUEUE_FLAG_NO_SG_MERGE, q);
-
 	dm_table_verify_integrity(t);
 
 	/*
+	 * Some devices don't use blk_integrity but still want stable pages
+	 * because they do their own checksumming.
+	 */
+	if (dm_table_requires_stable_pages(t))
+		q->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
+	else
+		q->backing_dev_info->capabilities &= ~BDI_CAP_STABLE_WRITES;
+
+	/*
 	 * Determine whether or not this queue's I/O timings contribute
 	 * to the entropy pool, Only request-based targets use this.
 	 * Clear QUEUE_FLAG_ADD_RANDOM if any underlying device does not