Re: [WTF] utterly tasteless ABI in hfi1 (around ->write()/->write_iter())

[Linus Torvalds]

On Tue, Mar 15, 2016 at 9:17 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
>         Take a look at drivers/staging/rdma/hfi1/file_ops.c in -next and
> compare hfi1_write_iter() with hfi1_file_write().  Folks, this ABI is too
> ugly to live, let alone to be allowed breeding.
>
>         It's also brittle as hell - trivial massage around fs/read_write.c
> and fs/aio.c is quite capable of breaking that shit.  Arguably, IOCB_CMD_PWRITE
> and IOCB_CMD_PWRITEV both triggering your writev() semantics is an example of
> just such breakage.  Sigh...

We could just decide that if a file descriptor has both ->write and
->write_iter entities, we always pick ->write_iter in the vfs layer.

That way it's always consistent.

Simple ordering change in __vfs_write()..

We can switch is back later, but make sure it hits a release or two.
Or at least a few rc's, to flush out any problems.

Anybody who thinks that they can have different semantics for write()
and writev() is just completely broken.

              Linus