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, 83 insertions, 53 deletions

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 6f99907bc8d7..3019fe2e9df7 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -45,8 +45,8 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
 	 * give 25%, 25%, 50%, 50%, 50% memory for each components respectively
 	 */
 	if (type == FREE_NIDS) {
-		mem_size = (nm_i->fcnt * sizeof(struct free_nid)) >>
-							PAGE_SHIFT;
+		mem_size = (nm_i->nid_cnt[FREE_NID_LIST] *
+				sizeof(struct free_nid)) >> PAGE_SHIFT;
 		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 2);
 	} else if (type == NAT_ENTRIES) {
 		mem_size = (nm_i->nat_cnt * sizeof(struct nat_entry)) >>
@@ -1698,10 +1698,31 @@ static struct free_nid *__lookup_free_nid_list(struct f2fs_nm_info *nm_i,
 static void __del_from_free_nid_list(struct f2fs_nm_info *nm_i,
 						struct free_nid *i)
 {
-	list_del(&i->list);
 	radix_tree_delete(&nm_i->free_nid_root, i->nid);
 }
 
+static void __insert_nid_to_list(struct f2fs_sb_info *sbi,
+					struct free_nid *i, enum nid_list list)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+
+	f2fs_bug_on(sbi, list == FREE_NID_LIST ? i->state != NID_NEW :
+						i->state != NID_ALLOC);
+	nm_i->nid_cnt[list]++;
+	list_add_tail(&i->list, &nm_i->nid_list[list]);
+}
+
+static void __remove_nid_from_list(struct f2fs_sb_info *sbi,
+					struct free_nid *i, enum nid_list list)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+
+	f2fs_bug_on(sbi, list == FREE_NID_LIST ? i->state != NID_NEW :
+						i->state != NID_ALLOC);
+	nm_i->nid_cnt[list]--;
+	list_del(&i->list);
+}
+
 static int add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build)
 {
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
@@ -1732,33 +1753,33 @@ static int add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build)
 		return 0;
 	}
 
-	spin_lock(&nm_i->free_nid_list_lock);
+	spin_lock(&nm_i->nid_list_lock);
 	if (radix_tree_insert(&nm_i->free_nid_root, i->nid, i)) {
-		spin_unlock(&nm_i->free_nid_list_lock);
+		spin_unlock(&nm_i->nid_list_lock);
 		radix_tree_preload_end();
 		kmem_cache_free(free_nid_slab, i);
 		return 0;
 	}
-	list_add_tail(&i->list, &nm_i->free_nid_list);
-	nm_i->fcnt++;
-	spin_unlock(&nm_i->free_nid_list_lock);
+	__insert_nid_to_list(sbi, i, FREE_NID_LIST);
+	spin_unlock(&nm_i->nid_list_lock);
 	radix_tree_preload_end();
 	return 1;
 }
 
-static void remove_free_nid(struct f2fs_nm_info *nm_i, nid_t nid)
+static void remove_free_nid(struct f2fs_sb_info *sbi, nid_t nid)
 {
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct free_nid *i;
 	bool need_free = false;
 
-	spin_lock(&nm_i->free_nid_list_lock);
+	spin_lock(&nm_i->nid_list_lock);
 	i = __lookup_free_nid_list(nm_i, nid);
 	if (i && i->state == NID_NEW) {
+		__remove_nid_from_list(sbi, i, FREE_NID_LIST);
 		__del_from_free_nid_list(nm_i, i);
-		nm_i->fcnt--;
 		need_free = true;
 	}
-	spin_unlock(&nm_i->free_nid_list_lock);
+	spin_unlock(&nm_i->nid_list_lock);
 
 	if (need_free)
 		kmem_cache_free(free_nid_slab, i);
@@ -1797,7 +1818,7 @@ void __build_free_nids(struct f2fs_sb_info *sbi)
 	nid_t nid = nm_i->next_scan_nid;
 
 	/* Enough entries */
-	if (nm_i->fcnt >= NAT_ENTRY_PER_BLOCK)
+	if (nm_i->nid_cnt[FREE_NID_LIST] >= NAT_ENTRY_PER_BLOCK)
 		return;
 
 	/* readahead nat pages to be scanned */
@@ -1833,7 +1854,7 @@ void __build_free_nids(struct f2fs_sb_info *sbi)
 		if (addr == NULL_ADDR)
 			add_free_nid(sbi, nid, true);
 		else
-			remove_free_nid(nm_i, nid);
+			remove_free_nid(sbi, nid);
 	}
 	up_read(&curseg->journal_rwsem);
 	up_read(&nm_i->nat_tree_lock);
@@ -1866,23 +1887,22 @@ retry:
 	if (unlikely(sbi->total_valid_node_count + 1 > nm_i->available_nids))
 		return false;
 
-	spin_lock(&nm_i->free_nid_list_lock);
+	spin_lock(&nm_i->nid_list_lock);
 
 	/* We should not use stale free nids created by build_free_nids */
-	if (nm_i->fcnt && !on_build_free_nids(nm_i)) {
-		f2fs_bug_on(sbi, list_empty(&nm_i->free_nid_list));
-		list_for_each_entry(i, &nm_i->free_nid_list, list)
-			if (i->state == NID_NEW)
-				break;
-
-		f2fs_bug_on(sbi, i->state != NID_NEW);
+	if (nm_i->nid_cnt[FREE_NID_LIST] && !on_build_free_nids(nm_i)) {
+		f2fs_bug_on(sbi, list_empty(&nm_i->nid_list[FREE_NID_LIST]));
+		i = list_first_entry(&nm_i->nid_list[FREE_NID_LIST],
+					struct free_nid, list);
 		*nid = i->nid;
+
+		__remove_nid_from_list(sbi, i, FREE_NID_LIST);
 		i->state = NID_ALLOC;
-		nm_i->fcnt--;
-		spin_unlock(&nm_i->free_nid_list_lock);
+		__insert_nid_to_list(sbi, i, ALLOC_NID_LIST);
+		spin_unlock(&nm_i->nid_list_lock);
 		return true;
 	}
-	spin_unlock(&nm_i->free_nid_list_lock);
+	spin_unlock(&nm_i->nid_list_lock);
 
 	/* Let's scan nat pages and its caches to get free nids */
 	build_free_nids(sbi);
@@ -1897,11 +1917,12 @@ void alloc_nid_done(struct f2fs_sb_info *sbi, nid_t nid)
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct free_nid *i;
 
-	spin_lock(&nm_i->free_nid_list_lock);
+	spin_lock(&nm_i->nid_list_lock);
 	i = __lookup_free_nid_list(nm_i, nid);
-	f2fs_bug_on(sbi, !i || i->state != NID_ALLOC);
+	f2fs_bug_on(sbi, !i);
+	__remove_nid_from_list(sbi, i, ALLOC_NID_LIST);
 	__del_from_free_nid_list(nm_i, i);
-	spin_unlock(&nm_i->free_nid_list_lock);
+	spin_unlock(&nm_i->nid_list_lock);
 
 	kmem_cache_free(free_nid_slab, i);
 }
@@ -1918,17 +1939,20 @@ void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
 	if (!nid)
 		return;
 
-	spin_lock(&nm_i->free_nid_list_lock);
+	spin_lock(&nm_i->nid_list_lock);
 	i = __lookup_free_nid_list(nm_i, nid);
-	f2fs_bug_on(sbi, !i || i->state != NID_ALLOC);
+	f2fs_bug_on(sbi, !i);
+
+	__remove_nid_from_list(sbi, i, ALLOC_NID_LIST);
+
 	if (!available_free_memory(sbi, FREE_NIDS)) {
 		__del_from_free_nid_list(nm_i, i);
 		need_free = true;
 	} else {
 		i->state = NID_NEW;
-		nm_i->fcnt++;
+		__insert_nid_to_list(sbi, i, FREE_NID_LIST);
 	}
-	spin_unlock(&nm_i->free_nid_list_lock);
+	spin_unlock(&nm_i->nid_list_lock);
 
 	if (need_free)
 		kmem_cache_free(free_nid_slab, i);
@@ -1940,24 +1964,26 @@ int try_to_free_nids(struct f2fs_sb_info *sbi, int nr_shrink)
 	struct free_nid *i, *next;
 	int nr = nr_shrink;
 
-	if (nm_i->fcnt <= MAX_FREE_NIDS)
+	if (nm_i->nid_cnt[FREE_NID_LIST] <= MAX_FREE_NIDS)
 		return 0;
 
 	if (!mutex_trylock(&nm_i->build_lock))
 		return 0;
 
-	spin_lock(&nm_i->free_nid_list_lock);
-	list_for_each_entry_safe(i, next, &nm_i->free_nid_list, list) {
-		if (nr_shrink <= 0 || nm_i->fcnt <= MAX_FREE_NIDS)
+	spin_lock(&nm_i->nid_list_lock);
+	list_for_each_entry_safe(i, next, &nm_i->nid_list[FREE_NID_LIST],
+									list) {
+		if (nr_shrink <= 0 ||
+				nm_i->nid_cnt[FREE_NID_LIST] <= MAX_FREE_NIDS)
 			break;
-		if (i->state == NID_ALLOC)
-			continue;
+
+		__remove_nid_from_list(sbi, i, FREE_NID_LIST);
 		__del_from_free_nid_list(nm_i, i);
+
 		kmem_cache_free(free_nid_slab, i);
-		nm_i->fcnt--;
 		nr_shrink--;
 	}
-	spin_unlock(&nm_i->free_nid_list_lock);
+	spin_unlock(&nm_i->nid_list_lock);
 	mutex_unlock(&nm_i->build_lock);
 
 	return nr - nr_shrink;
@@ -2013,7 +2039,7 @@ recover_xnid:
 	if (unlikely(!inc_valid_node_count(sbi, inode)))
 		f2fs_bug_on(sbi, 1);
 
-	remove_free_nid(NM_I(sbi), new_xnid);
+	remove_free_nid(sbi, new_xnid);
 	get_node_info(sbi, new_xnid, &ni);
 	ni.ino = inode->i_ino;
 	set_node_addr(sbi, &ni, NEW_ADDR, false);
@@ -2043,7 +2069,7 @@ retry:
 	}
 
 	/* Should not use this inode from free nid list */
-	remove_free_nid(NM_I(sbi), ino);
+	remove_free_nid(sbi, ino);
 
 	if (!PageUptodate(ipage))
 		SetPageUptodate(ipage);
@@ -2277,20 +2303,22 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
 
 	/* not used nids: 0, node, meta, (and root counted as valid node) */
 	nm_i->available_nids = nm_i->max_nid - F2FS_RESERVED_NODE_NUM;
-	nm_i->fcnt = 0;
+	nm_i->nid_cnt[FREE_NID_LIST] = 0;
+	nm_i->nid_cnt[ALLOC_NID_LIST] = 0;
 	nm_i->nat_cnt = 0;
 	nm_i->ram_thresh = DEF_RAM_THRESHOLD;
 	nm_i->ra_nid_pages = DEF_RA_NID_PAGES;
 	nm_i->dirty_nats_ratio = DEF_DIRTY_NAT_RATIO_THRESHOLD;
 
 	INIT_RADIX_TREE(&nm_i->free_nid_root, GFP_ATOMIC);
-	INIT_LIST_HEAD(&nm_i->free_nid_list);
+	INIT_LIST_HEAD(&nm_i->nid_list[FREE_NID_LIST]);
+	INIT_LIST_HEAD(&nm_i->nid_list[ALLOC_NID_LIST]);
 	INIT_RADIX_TREE(&nm_i->nat_root, GFP_NOIO);
 	INIT_RADIX_TREE(&nm_i->nat_set_root, GFP_NOIO);
 	INIT_LIST_HEAD(&nm_i->nat_entries);
 
 	mutex_init(&nm_i->build_lock);
-	spin_lock_init(&nm_i->free_nid_list_lock);
+	spin_lock_init(&nm_i->nid_list_lock);
 	init_rwsem(&nm_i->nat_tree_lock);
 
 	nm_i->next_scan_nid = le32_to_cpu(sbi->ckpt->next_free_nid);
@@ -2335,17 +2363,19 @@ void destroy_node_manager(struct f2fs_sb_info *sbi)
 		return;
 
 	/* destroy free nid list */
-	spin_lock(&nm_i->free_nid_list_lock);
-	list_for_each_entry_safe(i, next_i, &nm_i->free_nid_list, list) {
-		f2fs_bug_on(sbi, i->state == NID_ALLOC);
+	spin_lock(&nm_i->nid_list_lock);
+	list_for_each_entry_safe(i, next_i, &nm_i->nid_list[FREE_NID_LIST],
+									list) {
+		__remove_nid_from_list(sbi, i, FREE_NID_LIST);
 		__del_from_free_nid_list(nm_i, i);
-		nm_i->fcnt--;
-		spin_unlock(&nm_i->free_nid_list_lock);
+		spin_unlock(&nm_i->nid_list_lock);
 		kmem_cache_free(free_nid_slab, i);
-		spin_lock(&nm_i->free_nid_list_lock);
+		spin_lock(&nm_i->nid_list_lock);
 	}
-	f2fs_bug_on(sbi, nm_i->fcnt);
-	spin_unlock(&nm_i->free_nid_list_lock);
+	f2fs_bug_on(sbi, nm_i->nid_cnt[FREE_NID_LIST]);
+	f2fs_bug_on(sbi, nm_i->nid_cnt[ALLOC_NID_LIST]);
+	f2fs_bug_on(sbi, !list_empty(&nm_i->nid_list[ALLOC_NID_LIST]));
+	spin_unlock(&nm_i->nid_list_lock);
 
 	/* destroy nat cache */
 	down_write(&nm_i->nat_tree_lock);