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>
e13b210f6f