[PATCH v2 0/2] fs: listmount()/statmount() fix and sample program

[Jeff Layton <jlayton@kernel.org>]

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.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
Changes in v2:
- fixed off-by-one bug in listmount last_mnt_id handling
- patch to add the security mount options to statmount()
- Link to v1: https://lore.kernel.org/r/20241112-statmount-v1-1-d98090c4c8be@kernel.org

---
Jeff Layton (2):
      samples: add a mountinfo program to demonstrate statmount()/listmount()
      fs: prepend statmount.mnt_opts string with security_sb_mnt_opts()

 fs/namespace.c          |   4 +
 samples/vfs/.gitignore  |   1 +
 samples/vfs/Makefile    |   2 +-
 samples/vfs/mountinfo.c | 271 ++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 277 insertions(+), 1 deletion(-)
---
base-commit: 4be4eaeb1a60a7d52e66123f2f52f2da017c9881
change-id: 20241112-statmount-77808bc02302

Best regards,
-- 
Jeff Layton <jlayton@kernel.org>