3 files changed, 26 insertions, 0 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 49da55c1528a..8c2a000cf3f5 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1698,6 +1698,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         }
 
         ti->num_flush_requests = 1;
+        ti->discard_zeroes_data_unsupported = 1;
+
         return 0;
 
 bad:
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 322669807077..bc04518e9d8b 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1283,6 +1283,22 @@ static bool dm_table_supports_flush(struct dm_table *t, unsigned flush)
         return 0;
 }
 
+static bool dm_table_discard_zeroes_data(struct dm_table *t)
+{
+        struct dm_target *ti;
+        unsigned i = 0;
+
+        /* Ensure that all targets supports discard_zeroes_data. */
+        while (i < dm_table_get_num_targets(t)) {
+                ti = dm_table_get_target(t, i++);
+
+                if (ti->discard_zeroes_data_unsupported)
+                        return 0;
+        }
+
+        return 1;
+}
+
 void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
                                struct queue_limits *limits)
 {
@@ -1305,6 +1321,9 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
         }
         blk_queue_flush(q, flush);
 
+        if (!dm_table_discard_zeroes_data(t))
+                q->limits.discard_zeroes_data = 0;
+
         dm_table_set_integrity(t);
 
         /*
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 3fa1f3d90ce0..99e3e50b5c57 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -197,6 +197,11 @@ struct dm_target {
          * whether or not its underlying devices have support.
          */
         unsigned discards_supported:1;
+
+        /*
+         * Set if this target does not return zeroes on discarded blocks.
+         */
+        unsigned discard_zeroes_data_unsupported:1;
 };
 
 /* Each target can link one of these into the table */