From e13b210f6f7bdc44dfee0a9bbd633a32db0d6333 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@www.linux.org.uk>
Date: Mon, 6 Jun 2005 13:36:06 -0700
Subject: [PATCH] [PATCH] namei fixes (10/19)

In open_namei(), __follow_down() loop turned into __follow_mount().
Instead of
	if we are on a mountpoint dentry
		if O_NOFOLLOW checks fail
			drop path.dentry
			drop nd
			return
		do equivalent of follow_mount(&path.mnt, &path.dentry)
		nd->mnt = path.mnt
we do
	if __follow_mount(path) had, indeed, traversed mountpoint
		/* now both nd->mnt and path.mnt are pinned down */
		if O_NOFOLLOW checks fail
			drop path.dentry
			drop path.mnt
			drop nd
			return
		mntput(nd->mnt)
		nd->mnt = path.mnt

Now __follow_down() can be folded into follow_down() - no other callers left.
We need to reorder dput()/mntput() there - same problem as in follow_mount().

Equivalent transformation + fix for a bug in O_NOFOLLOW handling - we used to
get -ELOOP if we had the same fs mounted on /foo and /bar, had something bound
on /bar/baz and tried to open /foo/baz with O_NOFOLLOW.  And fix of
too-early-mntput() race in follow_down()

Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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