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SubjectRe: [PATCH] nvmet: disable direct I/O when unavailable
On Mon, Feb 25, 2019 at 06:49:04AM -0800, Bart Van Assche wrote:
> On 2/25/19 1:37 AM, Johannes Thumshirn wrote:
> > On 24/02/2019 11:54, Max Gurtovoy wrote:
> > > What is the status of iSCSI/SRP targets in this case ?
> >
> > iSCSI/SRP passes in the following:
> >
> > /*
> > * Use O_DSYNC by default instead of O_SYNC to forgo syncing
> > * of pure timestamp updates.
> > */
> > flags = O_RDWR | O_CREAT | O_LARGEFILE | O_DSYNC;
>
> That code fragment comes from the LIO file backend. There is no requirement
> for a SCSI target core file backend to use O_DSYNC. SCST allows users to
> choose whether or not O_DSYNC should be used:

Yes, LIO file backend is the in-tree equivalent to NVMe's file backend. That's
why I copied it here.


>
> if (virt_dev->wt_flag && !virt_dev->nv_cache)
> open_flags |= O_DSYNC;
>

OK. Do your open_flags include O_DIRECT per default as well?

Byte,
Johannes
--
Johannes Thumshirn SUSE Labs Filesystems
jthumshirn@suse.de +49 911 74053 689
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