Hey,
Currently we take the read lock when looking for a mount namespace to
list mounts in. We can make this lockless at least for the simple search
case. I'm less certain about stuff like rb_prev() and rb_next() that we
use when listing mount namespaces via nsfs.
Creating a new mount namespace is a rather rare event compared with
querying mounts in a foreign mount namespace. Once this is picked up by
e.g., systemd to list mounts in another mount in isolated services and
containers this will be used a lot so this seems worthwhile doing.
Thanks!
Christian
---
Christian Brauner (5):
mount: remove inlude/nospec.h include
fs: add mount namespace to rbtree late
fs: lockless mntns rbtree lookup
selftests: remove unneeded include
samples: add test-list-all-mounts
fs/mount.h | 5 +-
fs/namespace.c | 102 ++++++++++-----
samples/vfs/.gitignore | 1 +
samples/vfs/Makefile | 2 +-
samples/vfs/test-list-all-mounts.c | 235 ++++++++++++++++++++++++++++++++++
tools/testing/selftests/pidfd/pidfd.h | 1 -
6 files changed, 311 insertions(+), 35 deletions(-)
---
base-commit: 40384c840ea1944d7c5a392e8975ed088ecf0b37
change-id: 20241207-work-mount-rbtree-lockless-7d4071b74f18
