f2fs: add a max block check for get_data_block_bmap

This patch adds a max block check for get_data_block_bmap.

Trinity test program will send a block number as parameter into
ioctl_fibmap, which will be used in get_node_path(), when the block
number large than f2fs max blocks, it will trigger kernel bug.
Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Xue Liu <liuxueliu.liu@huawei.com>
[Jaegeuk Kim: fix missing condition, pointed by Chao Yu]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -761,6 +761,10 @@ static int get_data_block_dio(struct inode *inode, sector_t iblock,
 static int get_data_block_bmap(struct inode *inode, sector_t iblock,
 			struct buffer_head *bh_result, int create)
 {
+	/* Block number less than F2FS MAX BLOCKS */
+	if (unlikely(iblock >= max_file_size(0)))
+		return -EFBIG;
+
 	return __get_data_block(inode, iblock, bh_result, create,
 						F2FS_GET_BLOCK_BMAP);
 }

fs/f2fs/f2fs.h

@@ -1726,6 +1726,7 @@ static inline int f2fs_add_link(struct dentry *dentry, struct inode *inode)
  * super.c
  */
 int f2fs_commit_super(struct f2fs_sb_info *, bool);
+loff_t max_file_size(unsigned bits);
 int f2fs_sync_fs(struct super_block *, int);
 extern __printf(3, 4)
 void f2fs_msg(struct super_block *, const char *, const char *, ...);

fs/f2fs/super.c

@@ -907,7 +907,7 @@ static const struct export_operations f2fs_export_ops = {
 	.get_parent = f2fs_get_parent,
 };
 
-static loff_t max_file_size(unsigned bits)
+loff_t max_file_size(unsigned bits)
 {
 	loff_t result = (DEF_ADDRS_PER_INODE - F2FS_INLINE_XATTR_ADDRS);
 	loff_t leaf_count = ADDRS_PER_BLOCK;