On 25/10/23 22:01, Miklos Szeredi wrote:
Implement mount querying syscalls agreed on at LSF/MM 2023.
Features:
- statx-like want/got mask
- allows returning ascii strings (fs type, root, mount point)
- returned buffer is relocatable (no pointers)
Still missing:
- man pages
- kselftest
Please find the test utility at the end of this mail.
Usage: statmnt [-l|-r] [-u] (mnt_id|path)
Git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git#statmount-v4
Changes v3..v4:
- incorporate patch moving list of mounts to an rbtree
- wire up syscalls for all archs
- add LISTMOUNT_RECURSIVE (depth first iteration of mount tree)
- add LSMT_ROOT (list root instead of a specific mount ID)
- list_for_each_entry_del() moved to a separate patchset
Changes v1..v3:
- rename statmnt(2) -> statmount(2)
- rename listmnt(2) -> listmount(2)
- make ABI 32bit compatible by passing 64bit args in a struct (tested on
i386 and x32)
- only accept new 64bit mount IDs
- fix compile on !CONFIG_PROC_FS
- call security_sb_statfs() in both syscalls
- make lookup_mnt_in_ns() static
- add LISTMOUNT_UNREACHABLE flag to listmnt() to explicitly ask for
listing unreachable mounts
- remove .sb_opts
- remove subtype from .fs_type
- return the number of bytes used (including strings) in .size
- rename .mountpoint -> .mnt_point
- point strings by an offset against char[] VLA at the end of the struct.
E.g. printf("fs_type: %s\n", st->str + st->fs_type);
- don't save string lengths
- extend spare space in struct statmnt (complete size is now 512 bytes)
Miklos Szeredi (6):
add unique mount ID
mounts: keep list of mounts in an rbtree
namespace: extract show_path() helper
add statmount(2) syscall
add listmount(2) syscall
wire up syscalls for statmount/listmount
arch/alpha/kernel/syscalls/syscall.tbl | 3 +
arch/arm/tools/syscall.tbl | 3 +
arch/arm64/include/asm/unistd32.h | 4 +
arch/ia64/kernel/syscalls/syscall.tbl | 3 +
arch/m68k/kernel/syscalls/syscall.tbl | 3 +
arch/microblaze/kernel/syscalls/syscall.tbl | 3 +
arch/mips/kernel/syscalls/syscall_n32.tbl | 3 +
arch/mips/kernel/syscalls/syscall_n64.tbl | 3 +
arch/mips/kernel/syscalls/syscall_o32.tbl | 3 +
arch/parisc/kernel/syscalls/syscall.tbl | 3 +
arch/powerpc/kernel/syscalls/syscall.tbl | 3 +
arch/s390/kernel/syscalls/syscall.tbl | 3 +
arch/sh/kernel/syscalls/syscall.tbl | 3 +
arch/sparc/kernel/syscalls/syscall.tbl | 3 +
arch/x86/entry/syscalls/syscall_32.tbl | 3 +
arch/x86/entry/syscalls/syscall_64.tbl | 2 +
arch/xtensa/kernel/syscalls/syscall.tbl | 3 +
fs/internal.h | 2 +
fs/mount.h | 27 +-
fs/namespace.c | 573 ++++++++++++++++----
fs/pnode.c | 2 +-
fs/proc_namespace.c | 13 +-
fs/stat.c | 9 +-
include/linux/mount.h | 5 +-
include/linux/syscalls.h | 8 +
include/uapi/asm-generic/unistd.h | 8 +-
include/uapi/linux/mount.h | 65 +++
include/uapi/linux/stat.h | 1 +
28 files changed, 635 insertions(+), 129 deletions(-)
Looks ok to me,covers the primary cases I needed when I worked
on using fsinfo() in systemd.
Karel, is there anything missing you would need for adding
libmount support?
Reviewed-by: Ian Kent <raven@xxxxxxxxxx>
