Re: [PATCH 2/2] Make write(2) interruptible by a signal

[Matthew Wilcox <matthew@wil.cx>]

On Thu, Nov 24, 2011 at 03:53:43PM -0500, Ted Ts'o wrote:
> On Thu, Nov 24, 2011 at 12:27:11PM -0700, Matthew Wilcox wrote:
> > On the other hand, if there was a crash mid-write, they might also get a
> > 36k write that actually hit media (right?  Or do we guarantee that on
> > reboot you see a multiple of 128k?)
> 
> Sure, but in the case the crash we expect things to be in a wonky
> state.  The problem is if people assume atomic writes to files in a
> non-crash case, which has been a traditional Unix/Linux "feature".
> It's guaranteed by the standards as much a "close() implies fsync()",
> but once application programmers start coding to such assumptions,
> they refuse to admit they were wrong, and blame the kernel
> programmers.

Sure, but resorting to kill -9 is almost the same as pushing the BRS.
Nobody's arguing in favour of non-fatal signals interrupting write()
[well, Honza was earlier, but we all talked him out of it].

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."