nfsd: reorganize filecache.c

nfsd: reorganize filecache.c

[ Upstream commit 4c8fb41f153f5a1220a2e1036f9ee7a7be3041fe ]

In a coming patch, we're going to rework how the filecache refcounting
works. Move some code around in the function to reduce the churn in the
later patches, and rename some of the functions with (hopefully) clearer
names: nfsd_file_flush becomes nfsd_file_fsync, and
nfsd_file_unhash_and_dispose is renamed to nfsd_file_unhash_and_queue.

Also, the nfsd_file_put_final tracepoint is renamed to nfsd_file_free,
to better match the name of the function from which it's called.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Stable-dep-of: 581a77c94d4e ("nfsd: fix handling of cached open files in nfsd4_open codepath")
Signed-off-by: Sasha Levin <sashal@kernel.org>