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[PATCH 19/19] shrinker: Kill old ->shrink API.

To: glommer@xxxxxxxxxxxxx
Subject: [PATCH 19/19] shrinker: Kill old ->shrink API.
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 28 Nov 2012 10:14:46 +1100
Cc: linux-kernel@xxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <1354058086-27937-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1354058086-27937-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

There are no more users of this API, so kill it dead, dead, dead and
quietly bury the corpse in a shallow, unmarked grave in a dark
forest deep in the hills...

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 include/linux/shrinker.h      |   15 +++++----------
 include/trace/events/vmscan.h |    4 ++--
 mm/vmscan.c                   |   39 ++++++++-------------------------------
 3 files changed, 15 insertions(+), 43 deletions(-)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index e71286f..d4636a0 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -7,14 +7,15 @@
  *
  * The 'gfpmask' refers to the allocation we are currently trying to
  * fulfil.
- *
- * Note that 'shrink' will be passed nr_to_scan == 0 when the VM is
- * querying the cache size, so a fastpath for that case is appropriate.
  */
 struct shrink_control {
        gfp_t gfp_mask;
 
-       /* How many slab objects shrinker() should scan and try to reclaim */
+       /*
+        * How many objects scan_objects should scan and try to reclaim.
+        * This is reset before every call, so it is safe for callees
+        * to modify.
+        */
        long nr_to_scan;
 
        /* shrink from these nodes */
@@ -24,11 +25,6 @@ struct shrink_control {
 /*
  * A callback you can register to apply pressure to ageable caches.
  *
- * @shrink() 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).
- *
  * @count_objects should return the number of freeable items in the cache. If
  * there are no objects to free or the number of freeable items cannot be
  * determined, it should return 0. No deadlock checks should be done during the
@@ -44,7 +40,6 @@ struct shrink_control {
  * @scan_objects will be made from the current reclaim context.
  */
 struct shrinker {
-       int (*shrink)(struct shrinker *, struct shrink_control *sc);
        long (*count_objects)(struct shrinker *, struct shrink_control *sc);
        long (*scan_objects)(struct shrinker *, struct shrink_control *sc);
 
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index 63cfccc..132a985 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -202,7 +202,7 @@ TRACE_EVENT(mm_shrink_slab_start,
 
        TP_fast_assign(
                __entry->shr = shr;
-               __entry->shrink = shr->shrink;
+               __entry->shrink = shr->scan_objects;
                __entry->nr_objects_to_shrink = nr_objects_to_shrink;
                __entry->gfp_flags = sc->gfp_mask;
                __entry->pgs_scanned = pgs_scanned;
@@ -241,7 +241,7 @@ TRACE_EVENT(mm_shrink_slab_end,
 
        TP_fast_assign(
                __entry->shr = shr;
-               __entry->shrink = shr->shrink;
+               __entry->shrink = shr->scan_objects;
                __entry->unused_scan = unused_scan_cnt;
                __entry->new_scan = new_scan_cnt;
                __entry->retval = shrinker_retval;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4a602ec..81731f5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -176,14 +176,6 @@ 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
@@ -229,11 +221,8 @@ unsigned long shrink_slab(struct shrink_control *sc,
                long batch_size = shrinker->batch ? shrinker->batch
                                                  : SHRINK_BATCH;
 
-               if (shrinker->scan_objects) {
-                       max_pass = shrinker->count_objects(shrinker, sc);
-                       WARN_ON(max_pass < 0);
-               } else
-                       max_pass = do_shrinker_shrink(shrinker, sc, 0);
+               max_pass = shrinker->count_objects(shrinker, sc);
+               WARN_ON(max_pass < 0);
                if (max_pass <= 0)
                        continue;
 
@@ -252,7 +241,7 @@ unsigned long shrink_slab(struct shrink_control *sc,
                if (total_scan < 0) {
                        printk(KERN_ERR
                        "shrink_slab: %pF negative objects to delete nr=%ld\n",
-                              shrinker->shrink, total_scan);
+                              shrinker->scan_objects, total_scan);
                        total_scan = max_pass;
                }
 
@@ -286,24 +275,12 @@ unsigned long shrink_slab(struct shrink_control *sc,
                while (total_scan >= batch_size) {
                        long ret;
 
-                       if (shrinker->scan_objects) {
-                               sc->nr_to_scan = batch_size;
-                               ret = shrinker->scan_objects(shrinker, sc);
+                       sc->nr_to_scan = batch_size;
+                       ret = shrinker->scan_objects(shrinker, sc);
 
-                               if (ret == -1)
-                                       break;
-                               freed += ret;
-                       } else {
-                               int nr_before;
-
-                               nr_before = do_shrinker_shrink(shrinker, sc, 0);
-                               ret = do_shrinker_shrink(shrinker, sc,
-                                                               batch_size);
-                               if (ret == -1)
-                                       break;
-                               if (ret < nr_before)
-                                       freed += nr_before - ret;
-                       }
+                       if (ret == -1)
+                               break;
+                       freed += ret;
                        count_vm_events(SLABS_SCANNED, batch_size);
                        total_scan -= batch_size;
 
-- 
1.7.10

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