tree b3be7d58b8eb9fd810636223f0458191ec1b9d75
parent 62c6943b4b1e818aea60c11c5a68a50785b83119
author Al Viro <viro@zeniv.linux.org.uk> 1241575844 -0400
committer Al Viro <viro@zeniv.linux.org.uk> 1244770567 -0400

No need to do lock_super() for exclusion in generic_shutdown_super()

We can't run into contention on it.  All other callers of lock_super()
either hold s_umount (and we have it exclusive) or hold an active
reference to superblock in question, which prevents the call of
generic_shutdown_super() while the reference is held.  So we can
replace lock_super(s) with get_fs_excl() in generic_shutdown_super()
(and corresponding change for unlock_super(), of course).

Since ext4 expects s_lock held for its put_super, take lock_super()
into it.  The rest of filesystems do not care at all.

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