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, 3 insertions, 4 deletions

diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
index efd5f970b501..0e6a33e81e5f 100644
--- a/fs/ext4/extents_status.h
+++ b/fs/ext4/extents_status.h
@@ -65,14 +65,13 @@ struct ext4_es_tree {
 };
 
 struct ext4_es_stats {
-        unsigned long es_stats_last_sorted;
         unsigned long es_stats_shrunk;
         unsigned long es_stats_cache_hits;
         unsigned long es_stats_cache_misses;
         u64 es_stats_scan_time;
         u64 es_stats_max_scan_time;
         struct percpu_counter es_stats_all_cnt;
-        struct percpu_counter es_stats_lru_cnt;
+        struct percpu_counter es_stats_shk_cnt;
 };
 
 extern int __init ext4_init_es(void);
@@ -151,7 +150,7 @@ static inline void ext4_es_store_pblock_status(struct extent_status *es,
 
 extern int ext4_es_register_shrinker(struct ext4_sb_info *sbi);
 extern void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi);
-extern void ext4_es_lru_add(struct inode *inode);
-extern void ext4_es_lru_del(struct inode *inode);
+extern void ext4_es_list_add(struct inode *inode);
+extern void ext4_es_list_del(struct inode *inode);
 
 #endif /* _EXT4_EXTENTS_STATUS_H */