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, 3 deletions

diff --git a/fs/mbcache.c b/fs/mbcache.c
index deeb9dc062d9..fbb1d02f8791 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -100,7 +100,6 @@ struct mb_cache {
 static LIST_HEAD(mb_cache_list);
 static LIST_HEAD(mb_cache_lru_list);
 static DEFINE_SPINLOCK(mb_cache_spinlock);
-static struct shrinker *mb_shrinker;
 
 static inline int
 mb_cache_indexes(struct mb_cache *cache)
@@ -118,6 +117,10 @@ mb_cache_indexes(struct mb_cache *cache)
 
 static int mb_cache_shrink_fn(int nr_to_scan, gfp_t gfp_mask);
 
+static struct shrinker mb_cache_shrinker = {
+        .shrink = mb_cache_shrink_fn,
+        .seeks = DEFAULT_SEEKS,
+};
 
 static inline int
 __mb_cache_entry_is_hashed(struct mb_cache_entry *ce)
@@ -662,13 +665,13 @@ mb_cache_entry_find_next(struct mb_cache_entry *prev, int index,
 
 static int __init init_mbcache(void)
 {
-        mb_shrinker = set_shrinker(DEFAULT_SEEKS, mb_cache_shrink_fn);
+        register_shrinker(&mb_cache_shrinker);
         return 0;
 }
 
 static void __exit exit_mbcache(void)
 {
-        remove_shrinker(mb_shrinker);
+        unregister_shrinker(&mb_cache_shrinker);
 }
 
 module_init(init_mbcache)