vmscan: change shrinker API by passing shrink_control struct

Change each shrinker's API by consolidating the existing parameters into
shrink_control struct.  This will simplify any further features added w/o
touching each file of shrinker.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: fix warning]
[kosaki.motohiro@jp.fujitsu.com: fix up new shrinker API]
[akpm@linux-foundation.org: fix xfs warning]
[akpm@linux-foundation.org: update gfs2]
Signed-off-by: Ying Han <yinghan@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 8 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 32cfa9602d00..5cbbf78eaac7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1166,18 +1166,20 @@ static inline void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
  * We consolidate the values for easier extention later.
  */
 struct shrink_control {
-        unsigned long nr_scanned;
         gfp_t gfp_mask;
+
+        /* How many slab objects shrinker() should scan and try to reclaim */
+        unsigned long nr_to_scan;
 };
 
 /*
  * A callback you can register to apply pressure to ageable caches.
  *
- * 'shrink' is passed a count 'nr_to_scan' and a 'gfpmask'.  It should
- * look through the least-recently-used 'nr_to_scan' entries and
- * attempt to free them up.  It should return the number of objects
- * which remain in the cache.  If it returns -1, it means it cannot do
- * any scanning at this time (eg. there is a risk of deadlock).
+ * 'sc' is passed shrink_control which includes a count 'nr_to_scan'
+ * and a 'gfpmask'.  It should look through the least-recently-used
+ * 'nr_to_scan' entries and attempt to free them up.  It should return
+ * the number of objects which remain in the cache.  If it returns -1, it means
+ * it cannot do any scanning at this time (eg. there is a risk of deadlock).
  *
  * The 'gfpmask' refers to the allocation we are currently trying to
  * fulfil.
@@ -1186,7 +1188,7 @@ struct shrink_control {
  * querying the cache size, so a fastpath for that case is appropriate.
  */
 struct shrinker {
-        int (*shrink)(struct shrinker *, int nr_to_scan, gfp_t gfp_mask);
+        int (*shrink)(struct shrinker *, struct shrink_control *sc);
         int seeks;      /* seeks to recreate an obj */
 
         /* These are for internal use */
@@ -1640,7 +1642,8 @@ int in_gate_area_no_mm(unsigned long addr);
 int drop_caches_sysctl_handler(struct ctl_table *, int,
                                         void __user *, size_t *, loff_t *);
 unsigned long shrink_slab(struct shrink_control *shrink,
-                                unsigned long lru_pages);
+                          unsigned long nr_pages_scanned,
+                          unsigned long lru_pages);
 
 #ifndef CONFIG_MMU
 #define randomize_va_space 0