minix_getattr(): don't bother with ->d_parent

we can find superblock easier, TYVM...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/minix/inode.c

@@ -596,8 +596,7 @@ static int minix_write_inode(struct inode *inode, struct writeback_control *wbc)
 
 int minix_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 {
-	struct inode *dir = dentry->d_parent->d_inode;
-	struct super_block *sb = dir->i_sb;
+	struct super_block *sb = dentry->d_sb;
 	generic_fillattr(dentry->d_inode, stat);
 	if (INODE_VERSION(dentry->d_inode) == MINIX_V1)
 		stat->blocks = (BLOCK_SIZE / 512) * V1_minix_blocks(stat->size, sb);