f2fs: shrink extent_cache entries

This patch registers shrinking extent_caches.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -767,7 +767,7 @@ void f2fs_preserve_extent_tree(struct inode *inode)
 		update_inode_page(inode);
 }
 
-void f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
+unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
 {
 	struct extent_tree *treevec[EXT_TREE_VEC_SIZE];
 	struct extent_node *en, *tmp;
@@ -778,10 +778,7 @@ void f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
 	unsigned int node_cnt = 0, tree_cnt = 0;
 
 	if (!test_opt(sbi, EXTENT_CACHE))
-		return;
-
-	if (available_free_memory(sbi, EXTENT_CACHE))
-		return;
+		return 0;
 
 	spin_lock(&sbi->extent_lock);
 	list_for_each_entry_safe(en, tmp, &sbi->extent_list, list) {
@@ -791,7 +788,9 @@ void f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
 	}
 	spin_unlock(&sbi->extent_lock);
 
-	down_read(&sbi->extent_tree_lock);
+	if (!down_read_trylock(&sbi->extent_tree_lock))
+		goto out;
+
 	while ((found = radix_tree_gang_lookup(&sbi->extent_tree_root,
 				(void **)treevec, ino, EXT_TREE_VEC_SIZE))) {
 		unsigned i;
@@ -809,7 +808,9 @@ void f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
 	}
 	up_read(&sbi->extent_tree_lock);
 
-	down_write(&sbi->extent_tree_lock);
+	if (!down_write_trylock(&sbi->extent_tree_lock))
+		goto out;
+
 	radix_tree_for_each_slot(slot, &sbi->extent_tree_root, &iter,
 							F2FS_ROOT_INO(sbi)) {
 		struct extent_tree *et = (struct extent_tree *)*slot;
@@ -822,8 +823,10 @@ void f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
 		}
 	}
 	up_write(&sbi->extent_tree_lock);
-
+out:
 	trace_f2fs_shrink_extent_tree(sbi, node_cnt, tree_cnt);
+
+	return node_cnt + tree_cnt;
 }
 
 void f2fs_destroy_extent_tree(struct inode *inode)

fs/f2fs/f2fs.h

@@ -1754,7 +1754,7 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *);
 void set_data_blkaddr(struct dnode_of_data *);
 int reserve_new_block(struct dnode_of_data *);
 int f2fs_reserve_block(struct dnode_of_data *, pgoff_t);
-void f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
+unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
 void f2fs_destroy_extent_tree(struct inode *);
 void f2fs_init_extent_cache(struct inode *, struct f2fs_extent *);
 void f2fs_update_extent_cache(struct dnode_of_data *);

fs/f2fs/segment.c

@@ -304,7 +304,8 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi)
 void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi)
 {
 	/* try to shrink extent cache when there is no enough memory */
-	f2fs_shrink_extent_tree(sbi, EXTENT_CACHE_SHRINK_NUMBER);
+	if (!available_free_memory(sbi, EXTENT_CACHE))
+		f2fs_shrink_extent_tree(sbi, EXTENT_CACHE_SHRINK_NUMBER);
 
 	/* check the # of cached NAT entries */
 	if (!available_free_memory(sbi, NAT_ENTRIES))

fs/f2fs/shrinker.c

@@ -23,6 +23,11 @@ static unsigned long __count_nat_entries(struct f2fs_sb_info *sbi)
 	return NM_I(sbi)->nat_cnt - NM_I(sbi)->dirty_nat_cnt;
 }
 
+static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
+{
+	return sbi->total_ext_tree + atomic_read(&sbi->total_ext_node);
+}
+
 unsigned long f2fs_shrink_count(struct shrinker *shrink,
 				struct shrink_control *sc)
 {
@@ -42,6 +47,9 @@ unsigned long f2fs_shrink_count(struct shrinker *shrink,
 		}
 		spin_unlock(&f2fs_list_lock);
 
+		/* count extent cache entries */
+		count += __count_extent_cache(sbi);
+
 		/* shrink clean nat cache entries */
 		count += __count_nat_entries(sbi);
 
@@ -82,8 +90,12 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink,
 
 		sbi->shrinker_run_no = run_no;
 
+		/* shrink extent cache entries */
+		freed += f2fs_shrink_extent_tree(sbi, nr >> 1);
+
 		/* shrink clean nat cache entries */
-		freed += try_to_free_nats(sbi, nr);
+		if (freed < nr)
+			freed += try_to_free_nats(sbi, nr - freed);
 
 		spin_lock(&f2fs_list_lock);
 		p = p->next;