ext4: use percpu counter for extent cache count

Use a percpu counter rather than atomic types for shrinker accounting.
There's no need for ultimate accuracy in the shrinker, so this
should come a little more cheaply.  The percpu struct is somewhat
large, but there was a big gap before the cache-aligned
s_es_lru_lock anyway, and it fits nicely in there.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 373d46cd5d3f..1ae5860b30a3 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -783,6 +783,7 @@ static void ext4_put_super(struct super_block *sb)
         percpu_counter_destroy(&sbi->s_freeinodes_counter);
         percpu_counter_destroy(&sbi->s_dirs_counter);
         percpu_counter_destroy(&sbi->s_dirtyclusters_counter);
+        percpu_counter_destroy(&sbi->s_extent_cache_cnt);
         brelse(sbi->s_sbh);
 #ifdef CONFIG_QUOTA
         for (i = 0; i < MAXQUOTAS; i++)
@@ -3688,6 +3689,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
         if (!err) {
                 err = percpu_counter_init(&sbi->s_dirtyclusters_counter, 0);
         }
+        if (!err) {
+                err = percpu_counter_init(&sbi->s_extent_cache_cnt, 0);
+        }
         if (err) {
                 ext4_msg(sb, KERN_ERR, "insufficient memory");
                 goto failed_mount3;
@@ -3993,6 +3997,7 @@ failed_mount3:
         percpu_counter_destroy(&sbi->s_freeinodes_counter);
         percpu_counter_destroy(&sbi->s_dirs_counter);
         percpu_counter_destroy(&sbi->s_dirtyclusters_counter);
+        percpu_counter_destroy(&sbi->s_extent_cache_cnt);
         if (sbi->s_mmp_tsk)
                 kthread_stop(sbi->s_mmp_tsk);
 failed_mount2: