1 files changed, 6 insertions, 4 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 192fdda0d56e..43bf4337859c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -595,6 +595,7 @@ static int btrfs_truncate_in_trans(struct btrfs_trans_handle *trans,
                            btrfs_file_extent_type(fi) !=
                            BTRFS_FILE_EXTENT_INLINE) {
                         u64 num_dec;
+                        extent_start = btrfs_file_extent_disk_blocknr(fi);
                         if (!del_item) {
                                 u64 orig_num_blocks =
                                         btrfs_file_extent_num_blocks(fi);
@@ -604,12 +605,13 @@ static int btrfs_truncate_in_trans(struct btrfs_trans_handle *trans,
                                 extent_num_blocks >>= inode->i_blkbits;
                                 btrfs_set_file_extent_num_blocks(fi,
                                                          extent_num_blocks);
-                                inode->i_blocks -= (orig_num_blocks -
-                                        extent_num_blocks) << 3;
+                                num_dec = (orig_num_blocks -
+                                           extent_num_blocks) << 3;
+                                if (extent_start != 0) {
+                                        inode->i_blocks -= num_dec;
+                                }
                                 btrfs_mark_buffer_dirty(path->nodes[0]);
                         } else {
-                                extent_start =
-                                        btrfs_file_extent_disk_blocknr(fi);
                                 extent_num_blocks =
                                         btrfs_file_extent_disk_num_blocks(fi);
                                 /* FIXME blocksize != 4096 */