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.
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
fs/namespace.c | 4 +++-
include/linux/proc_ns.h | 1 +
include/uapi/linux/nsfs.h | 1 +
3 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 2f2e93927f46..1829ab9a0a52 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -6174,9 +6174,11 @@ 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 3ff0bd381704..6258455e49a4 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 393778489d85..97d8d80d139f 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 */
--
2.47.2
