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, 1 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 0e73aa0a0e8b..cb9d05056b54 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -883,6 +883,11 @@ static int shrink_dcache_memory(int nr, gfp_t gfp_mask)
         return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
 }
 
+static struct shrinker dcache_shrinker = {
+        .shrink = shrink_dcache_memory,
+        .seeks = DEFAULT_SEEKS,
+};
+
 /**
  * d_alloc      -       allocate a dcache entry
  * @parent: parent of entry to allocate
@@ -2115,7 +2120,7 @@ static void __init dcache_init(unsigned long mempages)
         dentry_cache = KMEM_CACHE(dentry,
                 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
         
-        set_shrinker(DEFAULT_SEEKS, shrink_dcache_memory);
+        register_shrinker(&dcache_shrinker);
 
         /* Hash may have been set up in dcache_init_early */
         if (!hashdist)