Re: Deadlock in ceph journal

[Mark Kirkwood <mark.kirkwood@catalyst.net.nz>]

On 23/08/14 10:22, Somnath Roy wrote:
> I think it is using direct io for non-aio mode as well.
>
> Thanks & Regards
> Somnath
>

> One thing that does still concern me - if I understand what is happening here correctly: we write to the journal using aio until we want to stop doing writes (presumably pre closing it), then use normal io to write at that point.
>
> Given that we appear to be using direct io whenever we use aio, does this mean we end up mixing direct and buffered io to the journal [1] (or is the normal i.e non aio write still using direct io)?
>
>

Thanks Somnath,

I think you are correct (I missed the bit in FileJournal::_open that 
seems to cover this):


   if (forwrite) {
     flags = O_RDWR;
     if (directio)
       flags |= O_DIRECT | O_DSYNC;


i.e the journal is opened with DIRECT, so all writes (async or not) will 
be direct.

Cheers

Mark