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>

2 files changed, 20 insertions, 17 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 341341b2b47b..5c8f7e08928d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -241,10 +241,9 @@ void shake_page(struct page *p, int access)
 		do {
 			struct shrink_control shrink = {
 				.gfp_mask = GFP_KERNEL,
-				.nr_scanned = 1000,
 			};
 
-			nr = shrink_slab(&shrink, 1000);
+			nr = shrink_slab(&shrink, 1000, 1000);
 			if (page_count(p) == 1)
 				break;
 		} while (nr > 10);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index e4e245ed1a5b..7e0116150dc7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -202,6 +202,14 @@ void unregister_shrinker(struct shrinker *shrinker)
 }
 EXPORT_SYMBOL(unregister_shrinker);
 
+static inline int do_shrinker_shrink(struct shrinker *shrinker,
+				     struct shrink_control *sc,
+				     unsigned long nr_to_scan)
+{
+	sc->nr_to_scan = nr_to_scan;
+	return (*shrinker->shrink)(shrinker, sc);
+}
+
 #define SHRINK_BATCH 128
 /*
  * Call the shrink functions to age shrinkable caches
@@ -223,15 +231,14 @@ EXPORT_SYMBOL(unregister_shrinker);
  * Returns the number of slab objects which we shrunk.
  */
 unsigned long shrink_slab(struct shrink_control *shrink,
+			  unsigned long nr_pages_scanned,
 			  unsigned long lru_pages)
 {
 	struct shrinker *shrinker;
 	unsigned long ret = 0;
-	unsigned long scanned = shrink->nr_scanned;
-	gfp_t gfp_mask = shrink->gfp_mask;
 
-	if (scanned == 0)
-		scanned = SWAP_CLUSTER_MAX;
+	if (nr_pages_scanned == 0)
+		nr_pages_scanned = SWAP_CLUSTER_MAX;
 
 	if (!down_read_trylock(&shrinker_rwsem)) {
 		/* Assume we'll be able to shrink next time */
@@ -244,8 +251,8 @@ unsigned long shrink_slab(struct shrink_control *shrink,
 		unsigned long total_scan;
 		unsigned long max_pass;
 
-		max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask);
-		delta = (4 * scanned) / shrinker->seeks;
+		max_pass = do_shrinker_shrink(shrinker, shrink, 0);
+		delta = (4 * nr_pages_scanned) / shrinker->seeks;
 		delta *= max_pass;
 		do_div(delta, lru_pages + 1);
 		shrinker->nr += delta;
@@ -272,9 +279,9 @@ unsigned long shrink_slab(struct shrink_control *shrink,
 			int shrink_ret;
 			int nr_before;
 
-			nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask);
-			shrink_ret = (*shrinker->shrink)(shrinker, this_scan,
-								gfp_mask);
+			nr_before = do_shrinker_shrink(shrinker, shrink, 0);
+			shrink_ret = do_shrinker_shrink(shrinker, shrink,
+							this_scan);
 			if (shrink_ret == -1)
 				break;
 			if (shrink_ret < nr_before)
@@ -2072,8 +2079,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
 				lru_pages += zone_reclaimable_pages(zone);
 			}
 
-			shrink->nr_scanned = sc->nr_scanned;
-			shrink_slab(shrink, lru_pages);
+			shrink_slab(shrink, sc->nr_scanned, lru_pages);
 			if (reclaim_state) {
 				sc->nr_reclaimed += reclaim_state->reclaimed_slab;
 				reclaim_state->reclaimed_slab = 0;
@@ -2456,8 +2462,7 @@ loop_again:
 					end_zone, 0))
 				shrink_zone(priority, zone, &sc);
 			reclaim_state->reclaimed_slab = 0;
-			shrink.nr_scanned = sc.nr_scanned;
-			nr_slab = shrink_slab(&shrink, lru_pages);
+			nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages);
 			sc.nr_reclaimed += reclaim_state->reclaimed_slab;
 			total_scanned += sc.nr_scanned;
 
@@ -3025,7 +3030,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 	}
 
 	nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
-	shrink.nr_scanned = sc.nr_scanned;
 	if (nr_slab_pages0 > zone->min_slab_pages) {
 		/*
 		 * shrink_slab() does not currently allow us to determine how
@@ -3041,7 +3045,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 			unsigned long lru_pages = zone_reclaimable_pages(zone);
 
 			/* No reclaimable slab or very low memory pressure */
-			if (!shrink_slab(&shrink, lru_pages))
+			if (!shrink_slab(&shrink, sc.nr_scanned, lru_pages))
 				break;
 
 			/* Freed enough memory */