f2fs: split free nid list

During free nid allocation, in order to do preallocation, we will tag free
nid entry as allocated one and still leave it in free nid list, for other
allocators who want to grab free nids, it needs to traverse the free nid
list for lookup. It becomes overhead in scenario of allocating free nid
intensively by multithreads.

This patch splits free nid list to two list: {free,alloc}_nid_list, to
keep free nids and preallocated free nids separately, after that, traverse
latency will be gone, besides split nid_cnt for separate statistic.

Additionally, introduce __insert_nid_to_list and __remove_nid_from_list for
cleanup.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: modify f2fs_bug_on to avoid needless branches]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 10 insertions, 4 deletions

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9e8de18a168a..86b543c3defb 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -503,6 +503,12 @@ static inline void __try_update_largest_extent(struct inode *inode,
 	}
 }
 
+enum nid_list {
+	FREE_NID_LIST,
+	ALLOC_NID_LIST,
+	MAX_NID_LIST,
+};
+
 struct f2fs_nm_info {
 	block_t nat_blkaddr;		/* base disk address of NAT */
 	nid_t max_nid;			/* maximum possible node ids */
@@ -522,9 +528,9 @@ struct f2fs_nm_info {
 
 	/* free node ids management */
 	struct radix_tree_root free_nid_root;/* root of the free_nid cache */
-	struct list_head free_nid_list;	/* a list for free nids */
-	spinlock_t free_nid_list_lock;	/* protect free nid list */
-	unsigned int fcnt;		/* the number of free node id */
+	struct list_head nid_list[MAX_NID_LIST];/* lists for free nids */
+	unsigned int nid_cnt[MAX_NID_LIST];	/* the number of free node id */
+	spinlock_t nid_list_lock;	/* protect nid lists ops */
 	struct mutex build_lock;	/* lock for build free nids */
 
 	/* for checkpoint */
@@ -2184,7 +2190,7 @@ struct f2fs_stat_info {
 	s64 ndirty_node, ndirty_dent, ndirty_meta, ndirty_data, ndirty_imeta;
 	s64 inmem_pages;
 	unsigned int ndirty_dirs, ndirty_files, ndirty_all;
-	int nats, dirty_nats, sits, dirty_sits, fnids;
+	int nats, dirty_nats, sits, dirty_sits, free_nids, alloc_nids;
 	int total_count, utilization;
 	int bg_gc, wb_bios;
 	int inline_xattr, inline_inode, inline_dir, orphans;