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, 4 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index a2b1af89ca1a..adffe1615c51 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -300,7 +300,10 @@ static const struct super_operations nfs4_sops = {
 };
 #endif
 
-static struct shrinker *acl_shrinker;
+static struct shrinker acl_shrinker = {
+        .shrink         = nfs_access_cache_shrinker,
+        .seeks          = DEFAULT_SEEKS,
+};
 
 /*
  * Register the NFS filesystems
@@ -321,7 +324,7 @@ int __init register_nfs_fs(void)
         if (ret < 0)
                 goto error_2;
 #endif
-        acl_shrinker = set_shrinker(DEFAULT_SEEKS, nfs_access_cache_shrinker);
+        register_shrinker(&acl_shrinker);
         return 0;
 
 #ifdef CONFIG_NFS_V4
@@ -339,8 +342,7 @@ error_0:
  */
 void __exit unregister_nfs_fs(void)
 {
-        if (acl_shrinker != NULL)
-                remove_shrinker(acl_shrinker);
+        unregister_shrinker(&acl_shrinker);
 #ifdef CONFIG_NFS_V4
         unregister_filesystem(&nfs4_fs_type);
         nfs_unregister_sysctl();