ocfs2/xattr: Fix a bug in xattr allocation estimation

When we extend one xattr's value to a large size, the old value size might
be smaller than the size of a value root. In those cases, we still need to
guess the metadata allocation.
Reported-by: Tiger Yang <tiger.yang@oracle.com>
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/xattr.c

@@ -2270,6 +2270,7 @@ static int ocfs2_calc_xattr_set_need(struct inode *inode,
 								 value_size);
 			xv = (struct ocfs2_xattr_value_root *)
 			     (base + name_offset + name_len);
+			value_size = OCFS2_XATTR_ROOT_SIZE;
 		} else
 			xv = &def_xv.xv;
 
@@ -2283,6 +2284,7 @@ static int ocfs2_calc_xattr_set_need(struct inode *inode,
 							     &xv->xr_list,
 							     new_clusters -
 							     old_clusters);
+			if (value_size >= OCFS2_XATTR_ROOT_SIZE)
 				goto out;
 		}
 	} else {