[PATCH v6 20/31] shrinker: Kill old ->shrink API.

Glauber Costa
2013-05-12T18:13:41Z

From: Dave Chinner <dchinner@redhat.com>

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...

[ glommer: added flowers to the grave ]
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Glauber Costa <glommer@openvz.org>
Reviewed-by: Greg Thelen <gthelen@google.com>
Acked-by: Mel Gorman <mgorman@suse.de>
---
include/linux/shrinker.h | 15 +++++----------
include/trace/events/vmscan.h | 4 ++--
mm/vmscan.c | 38 ++++++++------------------------------
3 files changed, 15 insertions(+), 42 deletions(-)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 98be3ab..00a3e57 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 35a6a9b..64f66f6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -177,14 +177,6 @@ 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
@@ -230,11 +222,8 @@ unsigned long shrink_slab(struct shrink_control *shrinkctl,
long batch_size = shrinker->batch ? shrinker->batch
: SHRINK_BATCH;

- if (shrinker->scan_objects) {
- max_pass = shrinker->count_objects(shrinker, shrinkctl);
- WARN_ON(max_pass < 0);
- } else
- max_pass = do_shrinker_shrink(shrinker, shrinkctl, 0);
+ max_pass = shrinker->count_objects(shrinker, shrinkctl);
+ WARN_ON(max_pass < 0);
if (max_pass <= 0)
continue;

@@ -253,7 +242,7 @@ unsigned long shrink_slab(struct shrink_control *shrinkctl,
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;
}

@@ -287,23 +276,12 @@ unsigned long shrink_slab(struct shrink_control *shrinkctl,
while (total_scan >= batch_size) {
long ret;

- if (shrinker->scan_objects) {
- shrinkctl->nr_to_scan = batch_size;
- ret = shrinker->scan_objects(shrinker, shrinkctl);
+ shrinkctl->nr_to_scan = batch_size;
+ ret = shrinker->scan_objects(shrinker, shrinkctl);

- if (ret == -1)
- break;
- freed += ret;
- } else {
- int nr_before;
- nr_before = do_shrinker_shrink(shrinker, shrinkctl, 0);
- ret = do_shrinker_shrink(shrinker, shrinkctl,
- 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;
--
1.8.1.4