From 09b31295f833031c88419550172703d45c5401e3 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 24 Jun 2024 11:49:47 -0400 Subject: [PATCH] fs: export the mount ns id via statmount In order to allow users to iterate through children mount namespaces via listmount we need a way for them to know what the ns id for the mount. Add a new field to statmount called mnt_ns_id which will carry the ns id for the given mount entry. Co-developed-by: Christian Brauner Signed-off-by: Josef Bacik Link: https://lore.kernel.org/r/6dabf437331fb7415d886f7c64b21cb2a50b1c66.1719243756.git.josef@toxicpanda.com Signed-off-by: Christian Brauner --- fs/namespace.c | 11 +++++++++++ include/uapi/linux/mount.h | 4 +++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/namespace.c b/fs/namespace.c index eebe9d912a719..ed2d9353e4be3 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4974,6 +4974,14 @@ static int statmount_fs_type(struct kstatmount *s, struct seq_file *seq) return 0; } +static void statmount_mnt_ns_id(struct kstatmount *s) +{ + struct mnt_namespace *ns = current->nsproxy->mnt_ns; + + s->sm.mask |= STATMOUNT_MNT_NS_ID; + s->sm.mnt_ns_id = ns->seq; +} + static int statmount_string(struct kstatmount *s, u64 flag) { int ret; @@ -5070,6 +5078,9 @@ static int do_statmount(struct kstatmount *s) if (!err && s->mask & STATMOUNT_MNT_POINT) err = statmount_string(s, STATMOUNT_MNT_POINT); + if (!err && s->mask & STATMOUNT_MNT_NS_ID) + statmount_mnt_ns_id(s); + if (err) return err; diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index 88d78de1519ff..a07508aee518b 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -172,7 +172,8 @@ struct statmount { __u64 propagate_from; /* Propagation from in current namespace */ __u32 mnt_root; /* [str] Root of mount relative to root of fs */ __u32 mnt_point; /* [str] Mountpoint relative to current root */ - __u64 __spare2[50]; + __u64 mnt_ns_id; /* ID of the mount namespace */ + __u64 __spare2[49]; char str[]; /* Variable size part containing strings */ }; @@ -202,6 +203,7 @@ struct mnt_id_req { #define STATMOUNT_MNT_ROOT 0x00000008U /* Want/got mnt_root */ #define STATMOUNT_MNT_POINT 0x00000010U /* Want/got mnt_point */ #define STATMOUNT_FS_TYPE 0x00000020U /* Want/got fs_type */ +#define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ /* * Special @mnt_id values that can be passed to listmount