Add return value checks for read & write calls in test_listmount_ns
function. This patch resolves below compilation warnings:
```
statmount_test_ns.c: In function ‘test_listmount_ns’:
statmount_test_ns.c:322:17: warning: ignoring return value of ‘write’
declared with attribute ‘warn_unused_result’ [-Wunused-result]
statmount_test_ns.c:323:17: warning: ignoring return value of ‘read’
declared with attribute ‘warn_unused_result’ [-Wunused-result]
```
Signed-off-by: Abhinav Jain <jain.abhinav177@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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Merge tag 'vfs-6.11.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs mount query updates from Christian Brauner:
"This contains work to extend the abilities of listmount() and
statmount() and various fixes and cleanups.
Features:
- Allow iterating through mounts via listmount() from newest to
oldest. This makes it possible for mount(8) to keep iterating the
mount table in reverse order so it gets newest mounts first.
- Relax permissions on listmount() and statmount().
It's not necessary to have capabilities in the initial namespace:
it is sufficient to have capabilities in the owning namespace of
the mount namespace we're located in to list unreachable mounts in
that namespace.
- Extend both listmount() and statmount() to list and stat mounts in
foreign mount namespaces.
Currently the only way to iterate over mount entries in mount
namespaces that aren't in the caller's mount namespace is by
crawling through /proc in order to find /proc/<pid>/mountinfo for
the relevant mount namespace.
This is both very clumsy and hugely inefficient. So extend struct
mnt_id_req with a new member that allows to specify the mount
namespace id of the mount namespace we want to look at.
Luckily internally we already have most of the infrastructure for
this so we just need to expose it to userspace. Give userspace a
way to retrieve the id of a mount namespace via statmount() and
through a new nsfs ioctl() on mount namespace file descriptor.
This comes with appropriate selftests.
- Expose mount options through statmount().
Currently if userspace wants to get mount options for a mount and
with statmount(), they still have to open /proc/<pid>/mountinfo to
parse mount options. Simply the information through statmount()
directly.
Afterwards it's possible to only rely on statmount() and
listmount() to retrieve all and more information than
/proc/<pid>/mountinfo provides.
This comes with appropriate selftests.
Fixes:
- Avoid copying to userspace under the namespace semaphore in
listmount.
Cleanups:
- Simplify the error handling in listmount by relying on our newly
added cleanup infrastructure.
- Refuse invalid mount ids early for both listmount and statmount"
* tag 'vfs-6.11.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: reject invalid last mount id early
fs: refuse mnt id requests with invalid ids early
fs: find rootfs mount of the mount namespace
fs: only copy to userspace on success in listmount()
sefltests: extend the statmount test for mount options
fs: use guard for namespace_sem in statmount()
fs: export mount options via statmount()
fs: rename show_mnt_opts -> show_vfsmnt_opts
selftests: add a test for the foreign mnt ns extensions
fs: add an ioctl to get the mnt ns id from nsfs
fs: Allow statmount() in foreign mount namespace
fs: Allow listmount() in foreign mount namespace
fs: export the mount ns id via statmount
fs: keep an index of current mount namespaces
fs: relax permissions for statmount()
listmount: allow listing in reverse order
fs: relax permissions for listmount()
fs: simplify error handling
fs: don't copy to userspace under namespace semaphore
path: add cleanup helper
Fix the following warnings by adding return check and error messages.
statmount_test.c: In function ‘cleanup_namespace’:
statmount_test.c:128:9: warning: ignoring return value of ‘fchdir’
declared with attribute ‘warn_unused_result’ [-Wunused-result]
128 | fchdir(orig_root);
| ^~~~~~~~~~~~~~~~~
statmount_test.c:129:9: warning: ignoring return value of ‘chroot’
declared with attribute ‘warn_unused_result’ [-Wunused-result]
129 | chroot(".");
| ^~~~~~~~~~~
Signed-off-by: Amer Al Shanawany <amer.shanawany@gmail.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
