1 files changed, 17 insertions, 5 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index f49475dfa954..7a15fcfb3e1f 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -198,14 +198,24 @@ int btrfs_truncate_free_space_cache(struct btrfs_root *root,
                                     struct inode *inode)
 {
         struct btrfs_block_rsv *rsv;
+        u64 needed_bytes;
         loff_t oldsize;
         int ret = 0;
 
         rsv = trans->block_rsv;
-        trans->block_rsv = root->orphan_block_rsv;
-        ret = btrfs_block_rsv_check(root, root->orphan_block_rsv, 5);
-        if (ret)
-                return ret;
+        trans->block_rsv = &root->fs_info->global_block_rsv;
+
+        /* 1 for slack space, 1 for updating the inode */
+        needed_bytes = btrfs_calc_trunc_metadata_size(root, 1) +
+                btrfs_calc_trans_metadata_size(root, 1);
+
+        spin_lock(&trans->block_rsv->lock);
+        if (trans->block_rsv->reserved < needed_bytes) {
+                spin_unlock(&trans->block_rsv->lock);
+                trans->block_rsv = rsv;
+                return -ENOSPC;
+        }
+        spin_unlock(&trans->block_rsv->lock);
 
         oldsize = i_size_read(inode);
         btrfs_i_size_write(inode, 0);
@@ -218,13 +228,15 @@ int btrfs_truncate_free_space_cache(struct btrfs_root *root,
         ret = btrfs_truncate_inode_items(trans, root, inode,
                                          0, BTRFS_EXTENT_DATA_KEY);
 
-        trans->block_rsv = rsv;
         if (ret) {
+                trans->block_rsv = rsv;
                 WARN_ON(1);
                 return ret;
         }
 
         ret = btrfs_update_inode(trans, root, inode);
+        trans->block_rsv = rsv;
+
         return ret;
 }