NFSD: Revert "NFSD: NFSv4 CLOSE should release an nfsd_file immediately"

NFSD: Revert "NFSD: NFSv4 CLOSE should release an nfsd_file immediately"

[ Upstream commit dcf3f80965ca787c70def402cdf1553c93c75529 ]

This reverts commit a08f29b107d0f9a2165ebdee1b9ee033dc88395a.

That commit attempted to make files available to other users as soon
as all NFSv4 clients were done with them, rather than waiting until
the filecache LRU had garbage collected them.

It gets the reference counting wrong, for one thing.

But it also misses that DELEGRETURN should release a file in the
same fashion. In fact, any nfsd_file_put() on an file held open
by an NFSv4 client needs potentially to release the file
immediately...

Clear the way for implementing that idea.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Stable-dep-of: 0b3a551fa58b ("nfsd: fix handling of cached open files in nfsd4_open codepath")
Signed-off-by: Sasha Levin <sashal@kernel.org>