1 files changed, 25 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index fff219ed61d9..e63b3b4bed7c 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -18,6 +18,7 @@
 #include <linux/sched.h>
 #include <linux/pagemap.h>
 #include <linux/writeback.h>
+#include <linux/blkdev.h>
 #include "hash.h"
 #include "crc32c.h"
 #include "ctree.h"
@@ -1716,6 +1717,10 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
         if (refs == 0) {
                 u64 super_used;
                 u64 root_used;
+#ifdef BIO_RW_DISCARD
+                u64 map_length = num_bytes;
+                struct btrfs_multi_bio *multi = NULL;
+#endif
 
                 if (pin) {
                         ret = pin_down_bytes(root, bytenr, num_bytes, 0);
@@ -1743,6 +1748,26 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                 ret = update_block_group(trans, root, bytenr, num_bytes, 0,
                                          mark_free);
                 BUG_ON(ret);
+
+#ifdef BIO_RW_DISCARD
+                /* Tell the block device(s) that the sectors can be discarded */
+                ret = btrfs_map_block(&root->fs_info->mapping_tree, READ,
+                                      bytenr, &map_length, &multi, 0);
+                if (!ret) {
+                        struct btrfs_bio_stripe *stripe = multi->stripes;
+                        int i;
+
+                        if (map_length > num_bytes)
+                                map_length = num_bytes;
+
+                        for (i = 0; i < multi->num_stripes; i++, stripe++) {
+                                blkdev_issue_discard(stripe->dev->bdev,
+                                                     stripe->physical >> 9,
+                                                     map_length >> 9);
+                        }
+                        kfree(multi);
+                }
+#endif
         }
         btrfs_free_path(path);
         finish_current_insert(trans, extent_root);