don't bother with ->d_inode->i_sb - it's always equal to ->d_sb

... and neither can ever be NULL

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 48e4b89..5611ec9 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1638,13 +1638,13 @@
 	ino = le32_to_cpu(de->inode);
 	brelse(bh);
 
-	if (!ext4_valid_inum(d_inode(child)->i_sb, ino)) {
+	if (!ext4_valid_inum(child->d_sb, ino)) {
 		EXT4_ERROR_INODE(d_inode(child),
 				 "bad parent inode number: %u", ino);
 		return ERR_PTR(-EFSCORRUPTED);
 	}
 
-	return d_obtain_alias(ext4_iget_normal(d_inode(child)->i_sb, ino));
+	return d_obtain_alias(ext4_iget_normal(child->d_sb, ino));
 }
 
 /*