Btrfs: don't reserve data with extents locked in btrfs_fallocate

btrfs_fallocate tries to allocate space only if ranges in the file don't
already exist.  But the enospc checks it does are not allowed with
extents locked.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 10 insertions, 15 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 0f61e11a2998..0621a3a7d5d1 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1604,6 +1604,14 @@ static long btrfs_fallocate(struct file *file, int mode,
                 return -EOPNOTSUPP;
 
         /*
+         * Make sure we have enough space before we do the
+         * allocation.
+         */
+        ret = btrfs_check_data_free_space(inode, len);
+        if (ret)
+                return ret;
+
+        /*
          * wait for ordered IO before we have any locks.  We'll loop again
          * below with the locks held.
          */
@@ -1666,27 +1674,12 @@ static long btrfs_fallocate(struct file *file, int mode,
                 if (em->block_start == EXTENT_MAP_HOLE ||
                     (cur_offset >= inode->i_size &&
                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
-
-                        /*
-                         * Make sure we have enough space before we do the
-                         * allocation.
-                         */
-                        ret = btrfs_check_data_free_space(inode, last_byte -
-                                                          cur_offset);
-                        if (ret) {
-                                free_extent_map(em);
-                                break;
-                        }
-
                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
                                                         last_byte - cur_offset,
                                                         1 << inode->i_blkbits,
                                                         offset + len,
                                                         &alloc_hint);
 
-                        /* Let go of our reservation. */
-                        btrfs_free_reserved_data_space(inode, last_byte -
-                                                       cur_offset);
                         if (ret < 0) {
                                 free_extent_map(em);
                                 break;
@@ -1714,6 +1707,8 @@ static long btrfs_fallocate(struct file *file, int mode,
                              &cached_state, GFP_NOFS);
 out:
         mutex_unlock(&inode->i_mutex);
+        /* Let go of our reservation. */
+        btrfs_free_reserved_data_space(inode, len);
         return ret;
 }