diff --git a/fs/namespace.c b/fs/namespace.c
index 9d33909d0f9e..ecdc63ef881c 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -210,6 +210,7 @@ static struct mount *alloc_vfsmnt(const char *name)
 		INIT_HLIST_NODE(&mnt->mnt_mp_list);
 		INIT_LIST_HEAD(&mnt->mnt_umounting);
 		INIT_HLIST_HEAD(&mnt->mnt_stuck_children);
+		mnt->mnt.mnt_userns = &init_user_ns;
 	}
 	return mnt;
 
@@ -547,6 +548,11 @@ int sb_prepare_remount_readonly(struct super_block *sb)
 
 static void free_vfsmnt(struct mount *mnt)
 {
+	struct user_namespace *mnt_userns;
+
+	mnt_userns = mnt_user_ns(&mnt->mnt);
+	if (mnt_userns != &init_user_ns)
+		put_user_ns(mnt_userns);
 	kfree_const(mnt->mnt_devname);
 #ifdef CONFIG_SMP
 	free_percpu(mnt->mnt_pcp);
@@ -1055,6 +1061,9 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
 	mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL);
 
 	atomic_inc(&sb->s_active);
+	mnt->mnt.mnt_userns = mnt_user_ns(&old->mnt);
+	if (mnt->mnt.mnt_userns != &init_user_ns)
+		mnt->mnt.mnt_userns = get_user_ns(mnt->mnt.mnt_userns);
 	mnt->mnt.mnt_sb = sb;
 	mnt->mnt.mnt_root = dget(root);
 	mnt->mnt_mountpoint = mnt->mnt.mnt_root;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fd47deea7c17..fd0b80e6361d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -39,6 +39,7 @@
 #include <linux/fs_types.h>
 #include <linux/build_bug.h>
 #include <linux/stddef.h>
+#include <linux/mount.h>
 
 #include <asm/byteorder.h>
 #include <uapi/linux/fs.h>
@@ -2231,6 +2232,7 @@ struct file_system_type {
 #define FS_HAS_SUBTYPE		4
 #define FS_USERNS_MOUNT		8	/* Can be mounted by userns root */
 #define FS_DISALLOW_NOTIFY_PERM	16	/* Disable fanotify permission events */
+#define FS_ALLOW_IDMAP         32      /* FS has been updated to handle vfs idmappings. */
 #define FS_THP_SUPPORT		8192	/* Remove once all fs converted */
 #define FS_RENAME_DOES_D_MOVE	32768	/* FS will handle d_move() during rename() internally. */
 	int (*init_fs_context)(struct fs_context *);
@@ -2517,6 +2519,10 @@ struct filename {
 };
 static_assert(offsetof(struct filename, iname) % sizeof(long) == 0);
 
+static inline struct user_namespace *file_mnt_user_ns(struct file *file)
+{
+	return mnt_user_ns(file->f_path.mnt);
+}
 extern long vfs_truncate(const struct path *, loff_t);
 extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,
 		       struct file *filp);
diff --git a/include/linux/mount.h b/include/linux/mount.h
index aaf343b38671..52de25e08319 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -72,8 +72,14 @@ struct vfsmount {
 	struct dentry *mnt_root;	/* root of the mounted tree */
 	struct super_block *mnt_sb;	/* pointer to superblock */
 	int mnt_flags;
+	struct user_namespace *mnt_userns;
 } __randomize_layout;
 
+static inline struct user_namespace *mnt_user_ns(const struct vfsmount *mnt)
+{
+	return mnt->mnt_userns;
+}
+
 struct file; /* forward dec */
 struct path;