f2fs: add f2fs_bug_on() to detect potential bug

Add f2fs_bug_on() to check whether memory preallocation will fail or
not after radix_tree_preload(GFP_NOFS | __GFP_NOFAIL).

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: chaseyu

fs/f2fs/checkpoint.c

@@ -504,6 +504,7 @@ static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino,
 {
 	struct inode_management *im = &sbi->im[type];
 	struct ino_entry *e = NULL, *new = NULL;
+	int ret;
 
 	if (type == FLUSH_INO) {
 		rcu_read_lock();
@@ -516,7 +517,8 @@ static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino,
 		new = f2fs_kmem_cache_alloc(ino_entry_slab,
 						GFP_NOFS, true, NULL);
 
-	radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
+	ret = radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
+	f2fs_bug_on(sbi, ret);
 
 	spin_lock(&im->ino_lock);
 	e = radix_tree_lookup(&im->ino_root, ino);

fs/f2fs/node.c

@@ -2309,7 +2309,7 @@ static bool add_free_nid(struct f2fs_sb_info *sbi,
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct free_nid *i, *e;
 	struct nat_entry *ne;
-	int err = -EINVAL;
+	int err;
 	bool ret = false;
 
 	/* 0 nid should not be used */
@@ -2323,7 +2323,10 @@ static bool add_free_nid(struct f2fs_sb_info *sbi,
 	i->nid = nid;
 	i->state = FREE_NID;
 
-	radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
+	err = radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
+	f2fs_bug_on(sbi, err);
+
+	err = -EINVAL;
 
 	spin_lock(&nm_i->nid_list_lock);