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 <[email protected]> Signed-off-by: Zheng Liu <[email protected]> Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Theodore Ts'o <[email protected]>
chewitt · Nov 25, 2014 · edaa53c · edaa53c
1 parent 2f8e0a7
commit edaa53c
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Showing 8 changed files with 118 additions and 153 deletions.
diff --git 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;

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
@@ -4632,7 +4632,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 
 	trace_ext4_ext_map_blocks_exit(inode, flags, map,
 				       err ? err : allocated);
-	ext4_es_lru_add(inode);
+	ext4_es_list_add(inode);
 	return err ? err : allocated;
 }
 
@@ -5191,7 +5191,7 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		error = ext4_fill_fiemap_extents(inode, start_blk,
 						 len_blks, fieinfo);
 	}
-	ext4_es_lru_add(inode);
+	ext4_es_list_add(inode);
 	return error;
 }