Re: Update of file offset on write() etc. is non-atomic with I/O

From: Linus Torvalds
Date: Mon Mar 03 2014 - 18:34:52 EST


On Mon, Mar 3, 2014 at 3:28 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> Umm... I would be very surprised if that worked well. You have just
> forced fdget() to comply to the ABI. And unless that has such structs
> returned in register pairs, there's no way for compiler to do about
> that.

Register pairs are very much a common return model.

And we've relied on that before. For example, 64-bit pte's on x86-32
very much does that whole thing with the "pte_t" union.

So you can now commence being surprised.

(Side note: I think sparc or something doesn't support it, and may
return things in memory. I can't really seem to find it in myself to
care)

Linus
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