mbcache: fix shrinker function return value

The shrinker function is supposed to return the number of cache
entries after shrinking, not before shrinking.  Fix that.

Based on a patch from Wang Sheng-Hui <crosslonelyover@gmail.com>.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 10 insertions, 17 deletions

diff --git a/fs/mbcache.c b/fs/mbcache.c
index 8a2cbd823079..cf4e6cdfd15b 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -176,22 +176,12 @@ static int
 mb_cache_shrink_fn(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
 {
         LIST_HEAD(free_list);
-        struct list_head *l, *ltmp;
+        struct mb_cache *cache;
+        struct mb_cache_entry *entry, *tmp;
         int count = 0;
 
-        spin_lock(&mb_cache_spinlock);
-        list_for_each(l, &mb_cache_list) {
-                struct mb_cache *cache =
-                        list_entry(l, struct mb_cache, c_cache_list);
-                mb_debug("cache %s (%d)", cache->c_name,
-                          atomic_read(&cache->c_entry_count));
-                count += atomic_read(&cache->c_entry_count);
-        }
         mb_debug("trying to free %d entries", nr_to_scan);
-        if (nr_to_scan == 0) {
-                spin_unlock(&mb_cache_spinlock);
-                goto out;
-        }
+        spin_lock(&mb_cache_spinlock);
         while (nr_to_scan-- && !list_empty(&mb_cache_lru_list)) {
                 struct mb_cache_entry *ce =
                         list_entry(mb_cache_lru_list.next,
@@ -199,12 +189,15 @@ mb_cache_shrink_fn(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
                 list_move_tail(&ce->e_lru_list, &free_list);
                 __mb_cache_entry_unhash(ce);
         }
+        list_for_each_entry(cache, &mb_cache_list, c_cache_list) {
+                mb_debug("cache %s (%d)", cache->c_name,
+                          atomic_read(&cache->c_entry_count));
+                count += atomic_read(&cache->c_entry_count);
+        }
         spin_unlock(&mb_cache_spinlock);
-        list_for_each_safe(l, ltmp, &free_list) {
-                __mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
-                                                   e_lru_list), gfp_mask);
+        list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) {
+                __mb_cache_entry_forget(entry, gfp_mask);
         }
-out:
         return (count / 100) * sysctl_vfs_cache_pressure;
 }