Re: [PATCH v3 0/2] fs: allow statmount to fetch the subtype and devname

[Jeff Layton]

On Mon, 2024-11-11 at 10:17 +0100, Christian Brauner wrote:
> On Thu, 07 Nov 2024 16:00:05 -0500, Jeff Layton wrote:
> > Meta has some internal logging that scrapes /proc/self/mountinfo today.
> > I'd like to convert it to use listmount()/statmount(), so we can do a
> > better job of monitoring with containers. We're missing some fields
> > though. This patchset adds them.
> > 
> > 
> 
> I know Karel has been wanting this for libmount as well. Thanks for
> doing this! It would be nice if you could also add some selftests!
> 

(cc'ing Karel)

Thanks. We may need to tweak this a bit, based on Miklos' comments
about how empty strings are handled now, but it shouldn't be too big a
change.

I actually have a related question about libmount: glibc doesn't
currently provide syscall wrappers for statmount() and listmount().
Would it make sense to have libmount provide those? We could copy the
wrappers in tools/testing/selftests/filesystems/statmount/statmount.h
to libmount.h.

It's error-prone and a pain to roll these yourself, and that would make
things simpler until someone is ready to do something for glibc.

Another idea might be to start a new userland header file that is just
a collection of static inline wrappers for syscalls that aren't
packaged in glibc.e.g.  pidfd_open also doesn't have glibc bindings, so
we could add that there too.

> ---
> 
> Applied to the vfs.misc branch of the vfs/vfs.git tree.
> Patches in the vfs.misc branch should appear in linux-next soon.
> 
> Please report any outstanding bugs that were missed during review in a
> new review to the original patch series allowing us to drop it.
> 
> It's encouraged to provide Acked-bys and Reviewed-bys even though the
> patch has now been applied. If possible patch trailers will be updated.
> 
> Note that commit hashes shown below are subject to change due to rebase,
> trailer updates or similar. If in doubt, please check the listed branch.
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
> branch: vfs.misc
> 
> [1/2] fs: add the ability for statmount() to report the fs_subtype
>       https://git.kernel.org/vfs/vfs/c/ddfdeccd46bd
> [2/2] fs: add the ability for statmount() to report the mnt_devname
>       https://git.kernel.org/vfs/vfs/c/6fb42b3c00cd

-- 
Jeff Layton <jlayton@xxxxxxxxxx>