The early return from copy_file_range when len is zero should check if the filesystem really implements this syscall, returning -EOPNOTSUPP if it doesn't, and 0 otherwise. Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> Signed-off-by: Luis Henriques <lhenriques@xxxxxxx> --- Hi! Since I got not feedback, I'm sending a patch that should fix this issue reported by 0day. Probably this should simply be squashed into v9, I can send v10 if you prefer that. Cheers, -- Luis fs/read_write.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/read_write.c b/fs/read_write.c index 9db7adf160d2..24b4bf704765 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1498,7 +1498,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, return ret; if (len == 0) - return 0; + return file_out->f_op->copy_file_range ? 0 : -EOPNOTSUPP; file_start_write(file_out);
