Merge tag 'vfs-6.14-rc1.mount.v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs mount updates from Christian Brauner:

- Add a mountinfo program to demonstrate statmount()/listm

Merge tag 'vfs-6.14-rc1.mount.v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs mount updates from Christian Brauner:

- Add a mountinfo program to demonstrate statmount()/listmount()

Add a new "mountinfo" sample userland program that demonstrates how
to use statmount() and listmount() to get at the same info that
/proc/pid/mountinfo provides

- Remove pointless nospec.h include

- Prepend statmount.mnt_opts string with security_sb_mnt_opts()

Currently these mount options aren't accessible via statmount()

- Add new mount namespaces to mount namespace rbtree outside of the
namespace semaphore

- Lockless mount namespace lookup

Currently we take the read lock when looking for a mount namespace to
list mounts in. We can make this lockless. The simple search case can
just use a sequence counter to detect concurrent changes to the
rbtree

For walking the list of mount namespaces sequentially via nsfs we
keep a separate rcu list as rb_prev() and rb_next() aren't usable
safely with rcu. Currently there is no primitive for retrieving the
previous list member. To do this we need a new deletion primitive
that doesn't poison the prev pointer and a corresponding retrieval
helper

Since creating mount namespaces is a relatively rare event compared
with querying mounts in a foreign mount namespace this is worth it.
Once libmount and systemd pick up this mechanism to list mounts in
foreign mount namespaces this will be used very frequently

- Add extended selftests for lockless mount namespace iteration

- Add a sample program to list all mounts on the system, i.e., in
all mount namespaces

- Improve mount namespace iteration performance

Make finding the last or first mount to start iterating the mount
namespace from an O(1) operation and add selftests for iterating the
mount table starting from the first and last mount

- Use an xarray for the old mount id

While the ida does use the xarray internally we can use it explicitly
which allows us to increment the unique mount id under the xa lock.
This allows us to remove the atomic as we're now allocating both ids
in one go

- Use a shared header for vfs sample programs

- Fix build warnings for new sample program to list all mounts

* tag 'vfs-6.14-rc1.mount.v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
samples/vfs: fix build warnings
samples/vfs: use shared header
samples/vfs/mountinfo: Use __u64 instead of uint64_t
fs: remove useless lockdep assertion
fs: use xarray for old mount id
selftests: add listmount() iteration tests
fs: cache first and last mount
samples: add test-list-all-mounts
selftests: remove unneeded include
selftests: add tests for mntns iteration
seltests: move nsfs into filesystems subfolder
fs: simplify rwlock to spinlock
fs: lockless mntns lookup for nsfs
rculist: add list_bidir_{del,prev}_rcu()
fs: lockless mntns rbtree lookup
fs: add mount namespace to rbtree late
fs: prepend statmount.mnt_opts string with security_sb_mnt_opts()
mount: remove inlude/nospec.h include
samples: add a mountinfo program to demonstrate statmount()/listmount()

show more ...

samples/vfs: fix build warnings

Fix build warnings reported from linux-next.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20250120192504.4a1965a0@canb.auug.o

samples/vfs: fix build warnings

Fix build warnings reported from linux-next.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20250120192504.4a1965a0@canb.auug.org.au
Signed-off-by: Christian Brauner <brauner@kernel.org>

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samples/vfs: use shared header

Share some infrastructure between sample programs and fix a build
failure that was reported.

Reported-by: Sasha Levin <sashal@kernel.org>
Link: https://lore.kernel.or

samples/vfs: use shared header

Share some infrastructure between sample programs and fix a build
failure that was reported.

Reported-by: Sasha Levin <sashal@kernel.org>
Link: https://lore.kernel.org/r/Z42UkSXx0MS9qZ9w@lappy
Link: https://qa-reports.linaro.org/lkft/sashal-linus-next/build/v6.13-rc7-511-g109a8e0fa9d6/testrun/26809210/suite/build/test/gcc-8-allyesconfig/log
Signed-off-by: Christian Brauner <brauner@kernel.org>

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Merge patch series "fs: lockless mntns lookup"

Christian Brauner <brauner@kernel.org> says:

Currently we take the read lock when looking for a mount namespace to
list mounts in. We can make this lo

Merge patch series "fs: lockless mntns lookup"

Christian Brauner <brauner@kernel.org> says:

Currently we take the read lock when looking for a mount namespace to
list mounts in. We can make this lockless. The simple search case can
just use a sequence counter to detect concurrent changes to the rbtree.

For walking the list of mount namespaces sequentially via nsfs we keep a
separate rcu list as rb_prev() and rb_next() aren't usable safely with
rcu.

Since creating mount namespaces is a relatively rare event compared with
querying mounts in a foreign mount namespace this is worth it. Once
libmount and systemd pick up this mechanism to list mounts in foreign
mount namespaces this will be used very frequently.

* patches from https://lore.kernel.org/r/20241213-work-mount-rbtree-lockless-v3-0-6e3cdaf9b280@kernel.org:
samples: add test-list-all-mounts
selftests: remove unneeded include
selftests: add tests for mntns iteration
seltests: move nsfs into filesystems subfolder
fs: simplify rwlock to spinlock
fs: lockless mntns lookup for nsfs
rculist: add list_bidir_{del,prev}_rcu()
fs: lockless mntns rbtree lookup
fs: add mount namespace to rbtree late
mount: remove inlude/nospec.h include

Link: https://lore.kernel.org/r/20241213-work-mount-rbtree-lockless-v3-0-6e3cdaf9b280@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

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samples: add test-list-all-mounts

Add a sample program illustrating how to list all mounts in all mount
namespaces.

Link: https://lore.kernel.org/r/20241213-work-mount-rbtree-lockless-v3-10-6e3cdaf

samples: add test-list-all-mounts

Add a sample program illustrating how to list all mounts in all mount
namespaces.

Link: https://lore.kernel.org/r/20241213-work-mount-rbtree-lockless-v3-10-6e3cdaf9b280@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

show more ...