tree d3c9332ab72cf5a4eba483ba1ff83c54ca4c42a0
parent e3c3d9c838d48c0341c40ea45ee087e3d8c8ea39
author Al Viro <viro@zeniv.linux.org.uk> 1310065438 -0400
committer Al Viro <viro@zeniv.linux.org.uk> 1311140657 -0400

Make ->d_sb assign-once and always non-NULL

New helper (non-exported, fs/internal.h-only): __d_alloc(sb, name).
Allocates dentry, sets its ->d_sb to given superblock and sets
->d_op accordingly.  Old d_alloc(NULL, name) callers are converted
to that (all of them know what superblock they want).  d_alloc()
itself is left only for parent != NULl case; uses __d_alloc(),
inserts result into the list of parent's children.

Note that now ->d_sb is assign-once and never NULL *and*
->d_parent is never NULL either.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>