Re: [PATCH 11/11] xfs: add media verification ioctl

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Jan 14, 2026 at 07:15:59AM +0100, Christoph Hellwig wrote:
> On Tue, Jan 13, 2026 at 10:07:05PM -0800, Darrick J. Wong wrote:
> > > a tunable is a better choice here at least for now.
> > 
> > <nod> I'll set iosize to 1MB by default and userspace can decrease it if
> > it so desires.
> > 
> > Also it occurs to me that max_hw_sectors_kb seems to be 128K for all of
> > my consumer nvme devices, and the fancy Intel ones too.  Funny that the
> > sata ssds set it to 4MB, but I guess capping at 128k is one way to
> > reduce the command latency...?  (Or the kernel's broken?  I can't figure
> > out how to get mpsmin with nvme-cli...)
> 
> mpsmin is basically always 4k.
> 
> 
> On something unrelated:  SSDs remap all the time by definition, and
> HDDs are really good at remapping bad sectors these days as well.
> So verifying blocks that do not actually contain file system (meta)data
> is pretty pointless.   Can we come up with a way to verify only blocks
> that have valid data in them, while still being resonably sequential?
> I.e. walk the rmap?

xfs_scrub phase6 already calls getfsmap to figure out which parts of the
disk actually contain written data of any kind and are worth verifying.

--D