1 files changed, 57 insertions, 4 deletions

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index f90069029aae..100368eb7991 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1212,6 +1212,41 @@ struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector)
         return &t->targets[(KEYS_PER_NODE * n) + k];
 }
 
+static int count_device(struct dm_target *ti, struct dm_dev *dev,
+                        sector_t start, sector_t len, void *data)
+{
+        unsigned *num_devices = data;
+
+        (*num_devices)++;
+
+        return 0;
+}
+
+/*
+ * Check whether a table has no data devices attached using each
+ * target's iterate_devices method.
+ * Returns false if the result is unknown because a target doesn't
+ * support iterate_devices.
+ */
+bool dm_table_has_no_data_devices(struct dm_table *table)
+{
+        struct dm_target *uninitialized_var(ti);
+        unsigned i = 0, num_devices = 0;
+
+        while (i < dm_table_get_num_targets(table)) {
+                ti = dm_table_get_target(table, i++);
+
+                if (!ti->type->iterate_devices)
+                        return false;
+
+                ti->type->iterate_devices(ti, count_device, &num_devices);
+                if (num_devices)
+                        return false;
+        }
+
+        return true;
+}
+
 /*
  * Establish the new table's queue_limits and validate them.
  */
@@ -1354,17 +1389,25 @@ static int device_is_nonrot(struct dm_target *ti, struct dm_dev *dev,
         return q && blk_queue_nonrot(q);
 }
 
-static bool dm_table_is_nonrot(struct dm_table *t)
+static int device_is_not_random(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 && !blk_queue_add_random(q);
+}
+
+static bool dm_table_all_devices_attribute(struct dm_table *t,
+                                           iterate_devices_callout_fn func)
 {
         struct dm_target *ti;
         unsigned i = 0;
 
-        /* Ensure that all underlying device are non-rotational. */
         while (i < dm_table_get_num_targets(t)) {
                 ti = dm_table_get_target(t, i++);
 
                 if (!ti->type->iterate_devices ||
-                    !ti->type->iterate_devices(ti, device_is_nonrot, NULL))
+                    !ti->type->iterate_devices(ti, func, NULL))
                         return 0;
         }
 
@@ -1396,7 +1439,8 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
         if (!dm_table_discard_zeroes_data(t))
                 q->limits.discard_zeroes_data = 0;
 
-        if (dm_table_is_nonrot(t))
+        /* Ensure that all underlying devices are non-rotational. */
+        if (dm_table_all_devices_attribute(t, device_is_nonrot))
                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
         else
                 queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);
@@ -1404,6 +1448,15 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
         dm_table_set_integrity(t);
 
         /*
+         * 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
+         * have it set.
+         */
+        if (blk_queue_add_random(q) && dm_table_all_devices_attribute(t, device_is_not_random))
+                queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, q);
+
+        /*
          * QUEUE_FLAG_STACKABLE must be set after all queue settings are
          * visible to other CPUs because, once the flag is set, incoming bios
          * are processed by request-based dm, which refers to the queue