From: Christian Brauner Date: Fri, 6 Jun 2025 09:45:09 +0000 (+0200) Subject: mntns: use stable inode number for initial mount ns X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7f4f229195b73606ded77e56943f463b78adf635;p=thirdparty%2Fkernel%2Flinux.git mntns: use stable inode number for initial mount ns Apart from the network and mount namespace all other namespaces expose a stable inode number and userspace has been relying on that for a very long time now. It's very much heavily used API. Align the mount namespace and use a stable inode number from the reserved procfs inode number space so this is consistent across all namespaces. Link: https://lore.kernel.org/20250606-work-nsfs-v1-3-b8749c9a8844@kernel.org Signed-off-by: Christian Brauner --- diff --git a/fs/namespace.c b/fs/namespace.c index e13d9ab4f5649..7ca4612c7ae92 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -6203,9 +6203,11 @@ static void __init init_mount_tree(void) if (IS_ERR(mnt)) panic("Can't create rootfs"); - ns = alloc_mnt_ns(&init_user_ns, false); + ns = alloc_mnt_ns(&init_user_ns, true); if (IS_ERR(ns)) panic("Can't allocate initial namespace"); + ns->seq = atomic64_inc_return(&mnt_ns_seq); + ns->ns.inum = PROC_MNT_INIT_INO; m = real_mount(mnt); ns->root = m; ns->nr_mounts = 1; diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h index 3ff0bd381704b..6258455e49a46 100644 --- a/include/linux/proc_ns.h +++ b/include/linux/proc_ns.h @@ -48,6 +48,7 @@ enum { PROC_CGROUP_INIT_INO = CGROUP_NS_INIT_INO, PROC_TIME_INIT_INO = TIME_NS_INIT_INO, PROC_NET_INIT_INO = NET_NS_INIT_INO, + PROC_MNT_INIT_INO = MNT_NS_INIT_INO, }; #ifdef CONFIG_PROC_FS diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h index 393778489d85e..97d8d80d139fc 100644 --- a/include/uapi/linux/nsfs.h +++ b/include/uapi/linux/nsfs.h @@ -50,6 +50,7 @@ enum init_ns_ino { CGROUP_NS_INIT_INO = 0xEFFFFFFBU, TIME_NS_INIT_INO = 0xEFFFFFFAU, NET_NS_INIT_INO = 0xEFFFFFF9U, + MNT_NS_INIT_INO = 0xEFFFFFF8U, }; #endif /* __LINUX_NSFS_H */