mm: clean up and kernelify shrinker registration

I can never remember what the function to register to receive VM pressure
is called.  I have to trace down from __alloc_pages() to find it.

It's called "set_shrinker()", and it needs Your Help.

1) Don't hide struct shrinker.  It contains no magic.
2) Don't allocate "struct shrinker".  It's not helpful.
3) Call them "register_shrinker" and "unregister_shrinker".
4) Call the function "shrink" not "shrinker".
5) Reduce the 17 lines of waffly comments to 13, but document it properly.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Chinner <dgc@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 5 deletions

diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index aa55d0a03e6f..29a8ecc60928 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -543,17 +543,18 @@ rpcauth_uptodatecred(struct rpc_task *task)
                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
 }
 
-
-static struct shrinker *rpc_cred_shrinker;
+static struct shrinker rpc_cred_shrinker = {
+        .shrink = rpcauth_cache_shrinker,
+        .seeks = DEFAULT_SEEKS,
+};
 
 void __init rpcauth_init_module(void)
 {
         rpc_init_authunix();
-        rpc_cred_shrinker = set_shrinker(DEFAULT_SEEKS, rpcauth_cache_shrinker);
+        register_shrinker(&rpc_cred_shrinker);
 }
 
 void __exit rpcauth_remove_module(void)
 {
-        if (rpc_cred_shrinker != NULL)
-                remove_shrinker(rpc_cred_shrinker);
+        unregister_shrinker(&rpc_cred_shrinker);
 }