mm: add context argument to shrinker callback

The current shrinker implementation requires the registered callback
to have global state to work from. This makes it difficult to shrink
caches that are not global (e.g. per-filesystem caches). Pass the shrinker
structure to the callback so that users can embed the shrinker structure
in the context the shrinker needs to operate on and get back to it in the
callback via container_of().

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 5 insertions, 3 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9c7e57cc63a3..199fa436c0dd 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -213,8 +213,9 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
         list_for_each_entry(shrinker, &shrinker_list, list) {
                 unsigned long long delta;
                 unsigned long total_scan;
-                unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);
+                unsigned long max_pass;
 
+                max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask);
                 delta = (4 * scanned) / shrinker->seeks;
                 delta *= max_pass;
                 do_div(delta, lru_pages + 1);
@@ -242,8 +243,9 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
                         int shrink_ret;
                         int nr_before;
 
-                        nr_before = (*shrinker->shrink)(0, gfp_mask);
-                        shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
+                        nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask);
+                        shrink_ret = (*shrinker->shrink)(shrinker, this_scan,
+                                                                gfp_mask);
                         if (shrink_ret == -1)
                                 break;
                         if (shrink_ret < nr_before)