Re: [PATCHv11 0/9] write hints with nvme fdp and scsi streams

Keith Busch
2024-11-12T14:25:49Z

On Tue, Nov 12, 2024 at 02:34:39PM +0100, Christoph Hellwig wrote:
> On Tue, Nov 12, 2024 at 06:56:25PM +0530, Kanchan Joshi wrote:
> > IMO, passthrough propagation of hints/streams should continue to remain
> > the default behavior as it applies on multiple filesystems. And more
> > active placement by FS should rather be enabled by some opt in (e.g.,
> > mount option). Such opt in will anyway be needed for other reasons (like
> > regression avoidance on a broken device).
>
> I feel like banging my head against the wall. No, passing through write
> streams is simply not acceptable without the file system being in
> control. I've said and explained this in detail about a dozend times
> and the file system actually needing to do data separation for it's own
> purpose doesn't go away by ignoring it.

But that's just an ideological decision that doesn't jive with how
people use these. The applications know how they use their data better
than the filesystem, so putting the filesystem in the way to force
streams look like zones is just a unnecessary layer of indirection
getting in the way.