Ext2: return ENOMEM rather than EIO if sb_getblk fails

As the only reason that sb_getblks fails is that allocation fails.
It will be better to use ENOMEM rather than EIO.

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 06209ec4..2d7557d 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -665,7 +665,7 @@
 			if (unlikely(!new_bh)) {
 				ext2_free_blocks(inode, block, 1);
 				mark_inode_dirty(inode);
-				error = -EIO;
+				error = -ENOMEM;
 				goto cleanup;
 			}
 			lock_buffer(new_bh);