1 files changed, 9 insertions, 4 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f46c57276844..5606361b5f04 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5800,7 +5800,7 @@ out_fail:
 }
 
 static int prealloc_file_range(struct inode *inode, u64 start, u64 end,
-                               u64 alloc_hint, int mode)
+                        u64 alloc_hint, int mode, loff_t actual_len)
 {
         struct btrfs_trans_handle *trans;
         struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -5809,6 +5809,7 @@ static int prealloc_file_range(struct inode *inode, u64 start, u64 end,
         u64 cur_offset = start;
         u64 num_bytes = end - start;
         int ret = 0;
+        u64 i_size;
 
         while (num_bytes > 0) {
                 alloc_size = min(num_bytes, root->fs_info->max_extent);
@@ -5847,8 +5848,12 @@ static int prealloc_file_range(struct inode *inode, u64 start, u64 end,
                 BTRFS_I(inode)->flags |= BTRFS_INODE_PREALLOC;
                 if (!(mode & FALLOC_FL_KEEP_SIZE) &&
                     cur_offset > inode->i_size) {
-                        i_size_write(inode, cur_offset);
-                        btrfs_ordered_update_i_size(inode, cur_offset, NULL);
+                        if (cur_offset > actual_len)
+                                i_size  = actual_len;
+                        else
+                                i_size = cur_offset;
+                        i_size_write(inode, i_size);
+                        btrfs_ordered_update_i_size(inode, i_size, NULL);
                 }
 
                 ret = btrfs_update_inode(trans, root, inode);
@@ -5941,7 +5946,7 @@ static long btrfs_fallocate(struct inode *inode, int mode,
                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
                         ret = prealloc_file_range(inode,
                                                   cur_offset, last_byte,
-                                                  alloc_hint, mode);
+                                                alloc_hint, mode, offset+len);
                         if (ret < 0) {
                                 free_extent_map(em);
                                 break;