1 files changed, 20 insertions, 5 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index f76b1fd160d4..aeb84469d2c4 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -293,15 +293,24 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
         struct btrfs_key key;
         struct btrfs_ioctl_defrag_range_args range;
         int num_defrag;
+        int index;
+        int ret;
 
         /* get the inode */
         key.objectid = defrag->root;
         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
         key.offset = (u64)-1;
+
+        index = srcu_read_lock(&fs_info->subvol_srcu);
+
         inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
         if (IS_ERR(inode_root)) {
-                kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
-                return PTR_ERR(inode_root);
+                ret = PTR_ERR(inode_root);
+                goto cleanup;
+        }
+        if (btrfs_root_refs(&inode_root->root_item) == 0) {
+                ret = -ENOENT;
+                goto cleanup;
         }
 
         key.objectid = defrag->ino;
@@ -309,9 +318,10 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
         key.offset = 0;
         inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
         if (IS_ERR(inode)) {
-                kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
-                return PTR_ERR(inode);
+                ret = PTR_ERR(inode);
+                goto cleanup;
         }
+        srcu_read_unlock(&fs_info->subvol_srcu, index);
 
         /* do a chunk of defrag */
         clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
@@ -346,6 +356,10 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
 
         iput(inode);
         return 0;
+cleanup:
+        srcu_read_unlock(&fs_info->subvol_srcu, index);
+        kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
+        return ret;
 }
 
 /*
@@ -1594,9 +1608,10 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
                 if (err < 0 && num_written > 0)
                         num_written = err;
         }
-out:
+
         if (sync)
                 atomic_dec(&BTRFS_I(inode)->sync_writers);
+out:
         sb_end_write(inode->i_sb);
         current->backing_dev_info = NULL;
         return num_written ? num_written : err;