[PATCH 2/5] f2fs: cache: shrink meta and node caches in f2fs_balance_fs_bg

[Chao Yu]

From: Chao Yu <chao@xxxxxxxxxx>

This patch introduces META_BLOCK and NODE_BLOCK memory types to monitor
meta and node cache usage against available free memory, and integrates
them into f2fs_balance_fs_bg().

In f2fs_balance_fs_bg(), shrink 128 clean cached blocks of each types when
memory is insufficient (cache memory usage is larger than 50% of low memory).

Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
 fs/f2fs/cache.c   | 12 ++++++++++++
 fs/f2fs/cache.h   |  6 ++++++
 fs/f2fs/node.c    | 10 ++++++++++
 fs/f2fs/node.h    |  2 ++
 fs/f2fs/segment.c |  8 ++++++++
 5 files changed, 38 insertions(+)

diff --git a/fs/f2fs/cache.c b/fs/f2fs/cache.c
index 04b5408cbc58..f385fe928b5b 100644
--- a/fs/f2fs/cache.c
+++ b/fs/f2fs/cache.c
@@ -669,6 +669,18 @@ unsigned long f2fs_shrink_cache(struct f2fs_sb_info *sbi,
 	return freed;
 }
 
+unsigned long f2fs_shrink_meta_cache(struct f2fs_sb_info *sbi,
+					unsigned long nr_to_scan)
+{
+	return f2fs_do_shrink_cache(META_CACHE(sbi), nr_to_scan);
+}
+
+unsigned long f2fs_shrink_node_cache(struct f2fs_sb_info *sbi,
+					unsigned long nr_to_scan)
+{
+	return f2fs_do_shrink_cache(NODE_CACHE(sbi), nr_to_scan);
+}
+
 static int f2fs_cache_writeback_kthread(void *data)
 {
 	struct f2fs_sb_info *sbi = data;
diff --git a/fs/f2fs/cache.h b/fs/f2fs/cache.h
index 6c4db910d767..3df3a562c46f 100644
--- a/fs/f2fs/cache.h
+++ b/fs/f2fs/cache.h
@@ -84,6 +84,8 @@ enum f2fs_cache_request_flag {
 
 #define F2FS_ONSTACK_CACHES		(32)
 
+#define METADATA_CACHE_SHRINK_NUMBER	(128)
+
 #define F2FS_CACHE_FLAG_TEST_FUNC(name, flagname)			\
 static inline bool f2fs_cache_test_##name(				\
 			const struct f2fs_cached_block *entry)		\
@@ -223,6 +225,10 @@ void f2fs_drop_cache_range(struct f2fs_cached_block_list *cache,
 
 unsigned long f2fs_shrink_cache(struct f2fs_sb_info *sbi,
 				unsigned long nr_to_scan);
+unsigned long f2fs_shrink_meta_cache(struct f2fs_sb_info *sbi,
+				unsigned long nr_to_scan);
+unsigned long f2fs_shrink_node_cache(struct f2fs_sb_info *sbi,
+				unsigned long nr_to_scan);
 
 #define DEF_DIRTY_CACHE_TIMEOUT 5000
 #define MIN_DIRTY_CACHE_TIMEOUT 100
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index be14dfa31e53..7b2ff2c3dd03 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -123,6 +123,16 @@ bool f2fs_available_free_memory(struct f2fs_sb_info *sbi, int type)
 #else
 		res = false;
 #endif
+	} else if (type == META_BLOCK) {
+		mem_size = (META_CACHE(sbi)->num_entries *
+				(sizeof(struct f2fs_cached_block) +
+				F2FS_BLKSIZE(sbi))) >> PAGE_SHIFT;
+		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
+	} else if (type == NODE_BLOCK) {
+		mem_size = (NODE_CACHE(sbi)->num_entries *
+				(sizeof(struct f2fs_cached_block) +
+				F2FS_BLKSIZE(sbi))) >> PAGE_SHIFT;
+		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
 	} else {
 		if (!bdi_wb_dirty_exceeded(sbi->sb->s_bdi))
 			return true;
diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index 2704a5c6a54d..ff1f04864391 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -158,6 +158,8 @@ enum mem_type {
 	AGE_EXTENT_CACHE,	/* indicates age extent cache */
 	DISCARD_CACHE,	/* indicates memory of cached discard cmds */
 	COMPRESS_BLOCK,	/* indicates memory of cached compressed blocks */
+	META_BLOCK,	/* indicates memory of cached meta blocks */
+	NODE_BLOCK,	/* indicates memory of cached node blocks */
 	BASE_CHECK,	/* check kernel status */
 };
 
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 794e0d99fc7c..dab66ab3311d 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -510,6 +510,14 @@ void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi, bool from_bg)
 		f2fs_shrink_age_extent_tree(sbi,
 				AGE_EXTENT_CACHE_SHRINK_NUMBER);
 
+	/* try to shrink meta cache when there is no enough memory */
+	if (!f2fs_available_free_memory(sbi, META_BLOCK))
+		f2fs_shrink_meta_cache(sbi, METADATA_CACHE_SHRINK_NUMBER);
+
+	/* try to shrink node cache when there is no enough memory */
+	if (!f2fs_available_free_memory(sbi, NODE_BLOCK))
+		f2fs_shrink_node_cache(sbi, METADATA_CACHE_SHRINK_NUMBER);
+
 	/* check the # of cached NAT entries */
 	if (!f2fs_available_free_memory(sbi, NAT_ENTRIES))
 		f2fs_try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK(sbi));
-- 
2.49.0