[Fwd: [PATCH] Fix race in xfs_write() between direct and buffered I/O with DMAPI]

[Lachlan McIlroy]

Christoph Hellwig wrote:
> On Tue, Dec 23, 2008 at 11:40:24AM +1100, Lachlan McIlroy wrote:
>> Christoph Hellwig wrote:
>>> Do you need more input on this one?
>> Actually I just might.  Based on your last reponse I wasn't sure if
>> you wanted me to make further changes.
> 
> Well, my reponse was that I think we could do it more effecient, but the
> patch still looks correct to me.
Okay great.  I'll check it in and we can improve it later when I understand
what you meant!

> 
>> Then I got side-tracked wondering
>> why we even have the 'goto retry' in the dmapi post event - why retry the
>> write if we get ENOSPC when we don't if dmapi is not enabled?  Could the
>> write get stuck in an infinite loop?
> 
> We only retry on ENOSPC if the dmapi nospace even is enabled, or am I
> missing something?
I don't think you're missing anything here.  I don't understand how the
DMAPI stuff works but I imagined the event was there to indicate that the
write failed but what I don't understand is why that justifies a retry.
Is there something about DMAPI that needs the write to succeed?