Do I need to link ops on the same FD?

[redbaron]

Are operations on same file descriptor implicitly serialized or not? For example, if I write and then read, should these ops be linked?

I know there can be a partial write,so it is probably not a good practice in real life, but I am just trying to understand what io_uring offers.

[axboe]

Nothing is serialized unless you ask for it to be, doesn't matter if the ops touch the same or different files.

Partial writes will be considered an error in terms of IOSQE_IO_LINK, so it would break the chain.

[redbaron]

I see. If fd is a TCP socket, partial write is expected behaviour, right? does it still break the chain?

[axboe]

As I wrote: "Partial writes will be considered an error in terms of IOSQE_IO_LINK, so it would break the chain.". IOSQE_IO_HARDLINK does not sever on errors or short IO, but IOSQE_IO_LINK does.

[isilence]

Just as Jens said for write requests. That also holds for all kinds of send requests (as well as recv) when you set MSG_WAITALL, but otherwise partial IO is considered a "success" and doesn't break links.