ext4: change LRU to round-robin in extent status tree shrinker

In this commit we discard the lru algorithm for inodes with extent
status tree because it takes significant effort to maintain a lru list
in extent status tree shrinker and the shrinker can take a long time to
scan this lru list in order to reclaim some objects.

We replace the lru ordering with a simple round-robin.  After that we
never need to keep a lru list.  That means that the list needn't be
sorted if the shrinker can not reclaim any objects in the first round.

Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 5 insertions, 5 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 98da4cda9d18..ab6caf55f5bf 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -878,10 +878,9 @@ struct ext4_inode_info {
         /* extents status tree */
         struct ext4_es_tree i_es_tree;
         rwlock_t i_es_lock;
-        struct list_head i_es_lru;
+        struct list_head i_es_list;
         unsigned int i_es_all_nr;       /* protected by i_es_lock */
-        unsigned int i_es_lru_nr;       /* protected by i_es_lock */
-        unsigned long i_touch_when;     /* jiffies of last accessing */
+        unsigned int i_es_shk_nr;       /* protected by i_es_lock */
 
         /* ialloc */
         ext4_group_t    i_last_alloc_group;
@@ -1322,10 +1321,11 @@ struct ext4_sb_info {
 
         /* Reclaim extents from extent status tree */
         struct shrinker s_es_shrinker;
-        struct list_head s_es_lru;
+        struct list_head s_es_list;
+        long s_es_nr_inode;
         struct ext4_es_stats s_es_stats;
         struct mb_cache *s_mb_cache;
-        spinlock_t s_es_lru_lock ____cacheline_aligned_in_smp;
+        spinlock_t s_es_lock ____cacheline_aligned_in_smp;
 
         /* Ratelimit ext4 messages. */
         struct ratelimit_state s_err_ratelimit_state;