Unverified Commit 7f4f2291 authored by Christian Brauner's avatar Christian Brauner
Browse files

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: default avatarChristian Brauner <brauner@kernel.org>
parent 9b0240b3

fs/namespace.c

+3 −1
Original line number Diff line number Diff line
@@ -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;

include/linux/proc_ns.h

+1 −0
Original line number Diff line number Diff line
@@ -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

include/uapi/linux/nsfs.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */