Merge patch series "fs: listmount()/statmount() fix and sample program"

Merge patch series "fs: listmount()/statmount() fix and sample program"

Jeff Layton <jlayton@kernel.org> says:

We had some recent queries internally asking how to use the new
statmount() and listmount() interfaces. I was doing some other work in
this area, so I whipped up this tool.

My hope is that this will represent something of a "rosetta stone" for
how to translate between mountinfo and statmount(), and an example for
other people looking to use the new interfaces.

It may also be possible to use this as the basis for a listmount() and
statmount() testcase. We can call this program, and compare its output
to the mountinfo file.

The second patch adds security mount options to the existing mnt_opts in
the statmount() interface, which I think is the final missing piece
here. The alternative to doing that would be to add a new string field
for that, but I'm not sure that's worthwhile.

* patches from https://lore.kernel.org/r/20241115-statmount-v2-0-cd29aeff9cbb@kernel.org:
  fs: prepend statmount.mnt_opts string with security_sb_mnt_opts()
  samples: add a mountinfo program to demonstrate statmount()/listmount()

Link: https://lore.kernel.org/r/20241115-statmount-v2-0-cd29aeff9cbb@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>