1 files changed, 20 insertions, 7 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ee73efe75423..62d49705d140 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -28,6 +28,7 @@
 #include "volumes.h"
 #include "locking.h"
 #include "ref-cache.h"
+#include "compat.h"
 
 #define PENDING_EXTENT_INSERT 0
 #define PENDING_EXTENT_DELETE 1
@@ -899,6 +900,17 @@ static int noinline remove_extent_backref(struct btrfs_trans_handle *trans,
         return ret;
 }
 
+static void btrfs_issue_discard(struct block_device *bdev,
+                                u64 start, u64 len)
+{
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,28)
+        blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL);
+#else
+        blkdev_issue_discard(bdev, start >> 9, len >> 9);
+#endif
+}
+
+
 static int noinline free_extents(struct btrfs_trans_handle *trans,
                                  struct btrfs_root *extent_root,
                                  struct list_head *del_list)
@@ -1108,6 +1120,7 @@ search:
                         BUG_ON(ret);
 
 #ifdef BIO_RW_DISCARD
+                        map_length = tmp->num_bytes;
                         ret = btrfs_map_block(&info->mapping_tree, READ,
                                               tmp->bytenr, &map_length, &multi,
                                               0);
@@ -1115,16 +1128,16 @@ search:
                                 struct btrfs_bio_stripe *stripe;
                                 int i;
 
-                                stripe = multi->stripe;
+                                stripe = multi->stripes;
 
                                 if (map_length > tmp->num_bytes)
                                         map_length = tmp->num_bytes;
 
                                 for (i = 0; i < multi->num_stripes;
                                      i++, stripe++)
-                                        blkdev_issue_discard(stripe->dev->bdev,
-                                                        stripe->physical >> 9,
-                                                        map_length >> 9);
+                                        btrfs_issue_discard(stripe->dev->bdev,
+                                                            stripe->physical,
+                                                            map_length);
                                 kfree(multi);
                         }
 #endif
@@ -2498,9 +2511,9 @@ static int __free_extent(struct btrfs_trans_handle *trans,
                                 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);
+                                btrfs_issue_discard(stripe->dev->bdev,
+                                                    stripe->physical,
+                                                     map_length);
                         }
                         kfree(multi);
                 }