listmount: allow listing in reverse order
util-linux is about to implement listmount() and statmount() support.
Karel requested the ability to scan the mount table in backwards order
because that's what libmount currently does in order to get the latest
mount first. We currently don't support this in listmount(). Add a new
LISTMOUNT_RESERVE flag to allow listing mounts in reverse order. For
example, listing all child mounts of /sys without LISTMOUNT_REVERSE
gives:
/sys/kernel/security @ mnt_id: 4294968369
/sys/fs/cgroup @ mnt_id: 4294968370
/sys/firmware/efi/efivars @ mnt_id: 4294968371
/sys/fs/bpf @ mnt_id: 4294968372
/sys/kernel/tracing @ mnt_id: 4294968373
/sys/kernel/debug @ mnt_id: 4294968374
/sys/fs/fuse/connections @ mnt_id: 4294968375
/sys/kernel/config @ mnt_id: 4294968376
whereas with LISTMOUNT_RESERVE it gives:
/sys/kernel/config @ mnt_id: 4294968376
/sys/fs/fuse/connections @ mnt_id: 4294968375
/sys/kernel/debug @ mnt_id: 4294968374
/sys/kernel/tracing @ mnt_id: 4294968373
/sys/fs/bpf @ mnt_id: 4294968372
/sys/firmware/efi/efivars @ mnt_id: 4294968371
/sys/fs/cgroup @ mnt_id: 4294968370
/sys/kernel/security @ mnt_id: 4294968369
Link: https://lore.kernel.org/r/20240607-vfs-listmount-reverse-v1-4-7877a2bfa5e5@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2 files changed
