f2fs: avoid race condition for shrinker count

Light reported sometimes shinker gets nat_cnt < dirty_nat_cnt resulting in
wrong do_shinker work. Let's avoid to return insane overflowed value by adding
single tracking value.

Reported-by: Light Hsieh <Light.Hsieh@mediatek.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 18 insertions, 11 deletions

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 42394de6c7eb..e65d73293a3f 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -62,8 +62,8 @@ bool f2fs_available_free_memory(struct f2fs_sb_info *sbi, int type)
 				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)) >>
-							PAGE_SHIFT;
+		mem_size = (nm_i->nat_cnt[TOTAL_NAT] *
+				sizeof(struct nat_entry)) >> PAGE_SHIFT;
 		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 2);
 		if (excess_cached_nats(sbi))
 			res = false;
@@ -177,7 +177,8 @@ static struct nat_entry *__init_nat_entry(struct f2fs_nm_info *nm_i,
 	list_add_tail(&ne->list, &nm_i->nat_entries);
 	spin_unlock(&nm_i->nat_list_lock);
 
-	nm_i->nat_cnt++;
+	nm_i->nat_cnt[TOTAL_NAT]++;
+	nm_i->nat_cnt[RECLAIMABLE_NAT]++;
 	return ne;
 }
 
@@ -207,7 +208,8 @@ static unsigned int __gang_lookup_nat_cache(struct f2fs_nm_info *nm_i,
 static void __del_from_nat_cache(struct f2fs_nm_info *nm_i, struct nat_entry *e)
 {
 	radix_tree_delete(&nm_i->nat_root, nat_get_nid(e));
-	nm_i->nat_cnt--;
+	nm_i->nat_cnt[TOTAL_NAT]--;
+	nm_i->nat_cnt[RECLAIMABLE_NAT]--;
 	__free_nat_entry(e);
 }
 
@@ -253,7 +255,8 @@ static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i,
 	if (get_nat_flag(ne, IS_DIRTY))
 		goto refresh_list;
 
-	nm_i->dirty_nat_cnt++;
+	nm_i->nat_cnt[DIRTY_NAT]++;
+	nm_i->nat_cnt[RECLAIMABLE_NAT]--;
 	set_nat_flag(ne, IS_DIRTY, true);
 refresh_list:
 	spin_lock(&nm_i->nat_list_lock);
@@ -273,7 +276,8 @@ static void __clear_nat_cache_dirty(struct f2fs_nm_info *nm_i,
 
 	set_nat_flag(ne, IS_DIRTY, false);
 	set->entry_cnt--;
-	nm_i->dirty_nat_cnt--;
+	nm_i->nat_cnt[DIRTY_NAT]--;
+	nm_i->nat_cnt[RECLAIMABLE_NAT]++;
 }
 
 static unsigned int __gang_lookup_nat_set(struct f2fs_nm_info *nm_i,
@@ -2944,14 +2948,17 @@ int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	LIST_HEAD(sets);
 	int err = 0;
 
-	/* during unmount, let's flush nat_bits before checking dirty_nat_cnt */
+	/*
+	 * during unmount, let's flush nat_bits before checking
+	 * nat_cnt[DIRTY_NAT].
+	 */
 	if (enabled_nat_bits(sbi, cpc)) {
 		down_write(&nm_i->nat_tree_lock);
 		remove_nats_in_journal(sbi);
 		up_write(&nm_i->nat_tree_lock);
 	}
 
-	if (!nm_i->dirty_nat_cnt)
+	if (!nm_i->nat_cnt[DIRTY_NAT])
 		return 0;
 
 	down_write(&nm_i->nat_tree_lock);
@@ -2962,7 +2969,8 @@ int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 	 * into nat entry set.
 	 */
 	if (enabled_nat_bits(sbi, cpc) ||
-		!__has_cursum_space(journal, nm_i->dirty_nat_cnt, NAT_JOURNAL))
+		!__has_cursum_space(journal,
+			nm_i->nat_cnt[DIRTY_NAT], NAT_JOURNAL))
 		remove_nats_in_journal(sbi);
 
 	while ((found = __gang_lookup_nat_set(nm_i,
@@ -3086,7 +3094,6 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
 						F2FS_RESERVED_NODE_NUM;
 	nm_i->nid_cnt[FREE_NID] = 0;
 	nm_i->nid_cnt[PREALLOC_NID] = 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;
@@ -3220,7 +3227,7 @@ void f2fs_destroy_node_manager(struct f2fs_sb_info *sbi)
 			__del_from_nat_cache(nm_i, natvec[idx]);
 		}
 	}
-	f2fs_bug_on(sbi, nm_i->nat_cnt);
+	f2fs_bug_on(sbi, nm_i->nat_cnt[TOTAL_NAT]);
 
 	/* destroy nat set cache */
 	nid = 0;