Re: [Qemu-devel] [PATCH] Asynchronous reliable and configurable cache flush

[Paul Brook <paul@codesourcery.com>]

> > > +    if (ret) {
> > > +        BADF("scsi-disc: IO error on flush: %s\n", strerror(-ret));
> >
> > This is wrong for two reasons: BADF already adds a suitable prefix,
> > and is for reporting qemu bugs (i.e. missing features or things that
> > should never happen). This is just a normal IO error, which we
> > correctly report to the guest.
>
> I don't think flush failures are a normal IO error.  They can only
> occur when the corresponding host block device is having serious
> trouble.  Normally (if it's actually a host disk) this is very bad.

In practice any IO error indicates that the target device is pretty screwed.
I don't see why flushes should be special. When caches are enabled I'd be 
fairly surprised if normal write operations ever returned an error.

Paul