Re: [PATCH V10 0/8] dax: prepare for famfs

[Ira Weiny]

Ira Weiny wrote:
> Alison Schofield wrote:
> > On Fri, Mar 27, 2026 at 09:03:26PM +0000, John Groves wrote:
> > > From: John Groves <john@xxxxxxxxxx>
> > > 

[snip]

> > > 
> > > Description:
> > > 
> > > This patch series introduces the required dax support for famfs.
> > > Previous versions of the famfs series included both dax and fuse patches.
> > > This series separates them into separate patch series' (and the fuse
> > > series dependends on this dax series).
> > > 
> > > The famfs user space code can be found at [1]
> > > 
> > > Dax Overview:
> > > 
> > > This series introduces a new "famfs mode" of devdax, whose driver is
> > > drivers/dax/fsdev.c. This driver supports dax_iomap_rw() and
> > > dax_iomap_fault() calls against a character dax instance. A dax device
> > > now can be converted among three modes: 'system-ram', 'devdax' and
> > > 'famfs' via daxctl or sysfs (e.g. unbind devdax and bind famfs instead).
> > > 
> > > In famfs mode, a dax device initializes its pages consistent with the
> > > fsdaxmode of pmem. Raw read/write/mmap are not supported in this mode,
> > > but famfs is happy in this mode - using dax_iomap_rw() for read/write and
> > > dax_iomap_fault() for mmap faults.
> > > 
> > 
> > Here's what I found:
> > 
> > famfs-v10 on 7.0-rc5 + ndctl v84:
> > 	dax suite all pass 13/13, so no regression appears
> > 
> > famfs-v10 on 7.0-rc5 +
> > (ndctl v84 w https://github.com/jagalactic/ndctl/tree/famfs
> > top 3 patches + edit daxctl-famfs.sh to use cxl-test:
> > 
> > 	existing dax suite keeps passing
> > 	daxctl-famfs.sh oops w the new test at # Restore original mode"
> > 	seems easy to repoduce, maybe cannot go back to system-ram???
> 
> John have you been able to reproduce this?
> 
> Ira