On 2025-08-21, Askar Safin [off-list ref] wrote:

 ---- On Tue, 12 Aug 2025 22:25:40 +0400  Aleksa Sarai [off-list ref] wrote --- 
 > On 2025-08-09, Aleksa Sarai [off-list ref] wrote:
 > > +Note that the Linux kernel reuses filesystem instances
 > > +for many filesystems,
 > > +so (depending on the filesystem being configured and parameters used)
 > > +it is possible for the filesystem instance "created" by
 > > +.B \%FSCONFIG_CMD_CREATE
 > > +to, in fact, be a reference
 > > +to an existing filesystem instance in the kernel.
 > > +The kernel will attempt to merge the specified parameters
 > > +of this filesystem configuration context
 > > +with those of the filesystem instance being reused,
 > > +but some parameters may be
 > > +.IR "silently ignored" .
 > 
 > While looking at this again, I realised this explanation is almost
 > certainly incorrect in a few places (and was based on a misunderstanding
 > of how sget_fc() works and how it interacts with vfs_get_tree()).
 > 
 > I'll rewrite this in the next version.

This recent patch seems to be relevant:
https://lore.kernel.org/all/20250816-debugfs-mount-opts-v3-1-d271dad57b5b@posteo.net/ (local)

I'm aware of that, I was in one of the previous threads. There are some
deeper consistency issues that I'm writing patches for at the moment.

I'm of two minds whether I should fix the behaviour and then re-send
man-pages with updated text (delaying the next round of man-page reviews
by a month) or just reduce the specificity of this text and then add
more details after it has been fixed.

-- 
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
https://www.cyphar.com/