f2fs: remove WARN_ON in f2fs_is_valid_blkaddr

Syzbot triggers two WARNs in f2fs_is_valid_blkaddr and
__is_bitmap_valid. For example, in f2fs_is_valid_blkaddr,
if type is DATA_GENERIC_ENHANCE or DATA_GENERIC_ENHANCE_READ,
it invokes WARN_ON if blkaddr is not in the right range.
The call trace is as follows:

 f2fs_get_node_info+0x45f/0x1070
 read_node_page+0x577/0x1190
 __get_node_page.part.0+0x9e/0x10e0
 __get_node_page
 f2fs_get_node_page+0x109/0x180
 do_read_inode
 f2fs_iget+0x2a5/0x58b0
 f2fs_fill_super+0x3b39/0x7ca0

Fix these two WARNs by replacing WARN_ON with dump_stack.

Reported-by: syzbot+763ae12a2ede1d99d4dc@syzkaller.appspotmail.com
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -158,7 +158,7 @@ static bool __is_bitmap_valid(struct f2fs_sb_info *sbi, block_t blkaddr,
 		f2fs_err(sbi, "Inconsistent error blkaddr:%u, sit bitmap:%d",
 			 blkaddr, exist);
 		set_sbi_flag(sbi, SBI_NEED_FSCK);
-		WARN_ON(1);
+		dump_stack();
 	}
 	return exist;
 }
@@ -196,7 +196,7 @@ bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
 			f2fs_warn(sbi, "access invalid blkaddr:%u",
 				  blkaddr);
 			set_sbi_flag(sbi, SBI_NEED_FSCK);
-			WARN_ON(1);
+			dump_stack();
 			return false;
 		} else {
 			return __is_bitmap_valid(sbi, blkaddr, type);