f2fs: fix to use per-inode maxbytes in f2fs_fiemap

F2FS inode may have different max size,
so change to use per-inode maxbytes.
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -1837,6 +1837,7 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	int ret = 0;
 	bool compr_cluster = false;
 	unsigned int cluster_size = F2FS_I(inode)->i_cluster_size;
+	loff_t maxbytes;
 
 	if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
 		ret = f2fs_precache_extents(inode);
@@ -1850,6 +1851,15 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 
 	inode_lock(inode);
 
+	maxbytes = max_file_blocks(inode) << F2FS_BLKSIZE_BITS;
+	if (start > maxbytes) {
+		ret = -EFBIG;
+		goto out;
+	}
+
+	if (len > maxbytes || (maxbytes - len) < start)
+		len = maxbytes - start;
+
 	if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
 		ret = f2fs_xattr_fiemap(inode, fieinfo);
 		goto out;