btrfs: return value from btrfs_mark_extent_written() in case of error

We always return 0 even in case of an error in btrfs_mark_extent_written().
Fix it to return proper error value in case of a failure. All callers
handle it.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: riteshharjani

fs/btrfs/file.c

@@ -1094,7 +1094,7 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 	int del_nr = 0;
 	int del_slot = 0;
 	int recow;
-	int ret;
+	int ret = 0;
 	u64 ino = btrfs_ino(inode);
 
 	path = btrfs_alloc_path();
@@ -1315,7 +1315,7 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 	}
 out:
 	btrfs_free_path(path);
-	return 0;
+	return ret;
 }
 
 /*