Merge tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping

Pull vfs idmapping updates from Christian Brauner:

 - Last cycle we introduced the dedicated struct mnt_idmap type for
   mount idmapping and the required infrastucture in 256c8aed2b42 ("fs:
   introduce dedicated idmap type for mounts"). As promised in last
   cycle's pull request message this converts everything to rely on
   struct mnt_idmap.

   Currently we still pass around the plain namespace that was attached
   to a mount. This is in general pretty convenient but it makes it easy
   to conflate namespaces that are relevant on the filesystem with
   namespaces that are relevant on the mount level. Especially for
   non-vfs developers without detailed knowledge in this area this was a
   potential source for bugs.

   This finishes the conversion. Instead of passing the plain namespace
   around this updates all places that currently take a pointer to a
   mnt_userns with a pointer to struct mnt_idmap.

   Now that the conversion is done all helpers down to the really
   low-level helpers only accept a struct mnt_idmap argument instead of
   two namespace arguments.

   Conflating mount and other idmappings will now cause the compiler to
   complain loudly thus eliminating the possibility of any bugs. This
   makes it impossible for filesystem developers to mix up mount and
   filesystem idmappings as they are two distinct types and require
   distinct helpers that cannot be used interchangeably.

   Everything associated with struct mnt_idmap is moved into a single
   separate file. With that change no code can poke around in struct
   mnt_idmap. It can only be interacted with through dedicated helpers.
   That means all filesystems are and all of the vfs is completely
   oblivious to the actual implementation of idmappings.

   We are now also able to extend struct mnt_idmap as we see fit. For
   example, we can decouple it completely from namespaces for users that
   don't require or don't want to use them at all. We can also extend
   the concept of idmappings so we can cover filesystem specific
   requirements.

   In combination with the vfs{g,u}id_t work we finished in v6.2 this
   makes this feature substantially more robust and thus difficult to
   implement wrong by a given filesystem and also protects the vfs.

 - Enable idmapped mounts for tmpfs and fulfill a longstanding request.

   A long-standing request from users had been to make it possible to
   create idmapped mounts for tmpfs. For example, to share the host's
   tmpfs mount between multiple sandboxes. This is a prerequisite for
   some advanced Kubernetes cases. Systemd also has a range of use-cases
   to increase service isolation. And there are more users of this.

   However, with all of the other work going on this was way down on the
   priority list but luckily someone other than ourselves picked this
   up.

   As usual the patch is tiny as all the infrastructure work had been
   done multiple kernel releases ago. In addition to all the tests that
   we already have I requested that Rodrigo add a dedicated tmpfs
   testsuite for idmapped mounts to xfstests. It is to be included into
   xfstests during the v6.3 development cycle. This should add a slew of
   additional tests.

* tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping: (26 commits)
  shmem: support idmapped mounts for tmpfs
  fs: move mnt_idmap
  fs: port vfs{g,u}id helpers to mnt_idmap
  fs: port fs{g,u}id helpers to mnt_idmap
  fs: port i_{g,u}id_into_vfs{g,u}id() to mnt_idmap
  fs: port i_{g,u}id_{needs_}update() to mnt_idmap
  quota: port to mnt_idmap
  fs: port privilege checking helpers to mnt_idmap
  fs: port inode_owner_or_capable() to mnt_idmap
  fs: port inode_init_owner() to mnt_idmap
  fs: port acl to mnt_idmap
  fs: port xattr to mnt_idmap
  fs: port ->permission() to pass mnt_idmap
  fs: port ->fileattr_set() to pass mnt_idmap
  fs: port ->set_acl() to pass mnt_idmap
  fs: port ->get_acl() to pass mnt_idmap
  fs: port ->tmpfile() to pass mnt_idmap
  fs: port ->rename() to pass mnt_idmap
  fs: port ->mknod() to pass mnt_idmap
  fs: port ->mkdir() to pass mnt_idmap
  ...

10 files changed, 79 insertions, 78 deletions

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index f61e37f4c8ff..fc25fb95d5fc 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -641,7 +641,7 @@ static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 	inode->i_state |= I_CREATING;
 	spin_unlock(&inode->i_lock);
 
-	inode_init_owner(&init_user_ns, inode, dentry->d_parent->d_inode, mode);
+	inode_init_owner(&nop_mnt_idmap, inode, dentry->d_parent->d_inode, mode);
 	attr.mode = inode->i_mode;
 
 	err = ovl_create_or_link(dentry, inode, &attr, false);
@@ -655,19 +655,19 @@ out:
 	return err;
 }
 
-static int ovl_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int ovl_create(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode, bool excl)
 {
 	return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
 }
 
-static int ovl_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+static int ovl_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 		     struct dentry *dentry, umode_t mode)
 {
 	return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
 }
 
-static int ovl_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+static int ovl_mknod(struct mnt_idmap *idmap, struct inode *dir,
 		     struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	/* Don't allow creation of "whiteout" on overlay */
@@ -677,7 +677,7 @@ static int ovl_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 	return ovl_create_object(dentry, mode, rdev, NULL);
 }
 
-static int ovl_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+static int ovl_symlink(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, const char *link)
 {
 	return ovl_create_object(dentry, S_IFLNK, 0, link);
@@ -1075,7 +1075,7 @@ static int ovl_set_redirect(struct dentry *dentry, bool samedir)
 	return err;
 }
 
-static int ovl_rename(struct user_namespace *mnt_userns, struct inode *olddir,
+static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 		      struct dentry *old, struct inode *newdir,
 		      struct dentry *new, unsigned int flags)
 {
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index a25bb3453dde..defd4e231ad2 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -392,8 +392,8 @@ static struct dentry *ovl_lookup_real_one(struct dentry *connected,
 	 */
 	take_dentry_name_snapshot(&name, real);
 	/*
-	 * No mnt_userns handling here: it's an internal lookup.  Could skip
-	 * permission checking altogether, but for now just use non-mnt_userns
+	 * No idmap handling here: it's an internal lookup.  Could skip
+	 * permission checking altogether, but for now just use non-idmap
 	 * transformed ids.
 	 */
 	this = lookup_one_len(name.name.name, connected, name.name.len);
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index c9d0c362c7ef..7c04f033aadd 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -42,7 +42,7 @@ static struct file *ovl_open_realfile(const struct file *file,
 {
 	struct inode *realinode = d_inode(realpath->dentry);
 	struct inode *inode = file_inode(file);
-	struct user_namespace *real_mnt_userns;
+	struct mnt_idmap *real_idmap;
 	struct file *realfile;
 	const struct cred *old_cred;
 	int flags = file->f_flags | OVL_OPEN_FLAGS;
@@ -53,12 +53,12 @@ static struct file *ovl_open_realfile(const struct file *file,
 		acc_mode |= MAY_APPEND;
 
 	old_cred = ovl_override_creds(inode->i_sb);
-	real_mnt_userns = mnt_user_ns(realpath->mnt);
-	err = inode_permission(real_mnt_userns, realinode, MAY_OPEN | acc_mode);
+	real_idmap = mnt_idmap(realpath->mnt);
+	err = inode_permission(real_idmap, realinode, MAY_OPEN | acc_mode);
 	if (err) {
 		realfile = ERR_PTR(err);
 	} else {
-		if (!inode_owner_or_capable(real_mnt_userns, realinode))
+		if (!inode_owner_or_capable(real_idmap, realinode))
 			flags &= ~O_NOATIME;
 
 		realfile = open_with_fake_path(&file->f_path, flags, realinode,
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index ee6dfa577c93..541cf3717fc2 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -19,7 +19,7 @@
 #include "overlayfs.h"
 
 
-int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		struct iattr *attr)
 {
 	int err;
@@ -28,7 +28,7 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 	struct dentry *upperdentry;
 	const struct cred *old_cred;
 
-	err = setattr_prepare(&init_user_ns, dentry, attr);
+	err = setattr_prepare(&nop_mnt_idmap, dentry, attr);
 	if (err)
 		return err;
 
@@ -153,7 +153,7 @@ static void ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
 	}
 }
 
-int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
 		struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	struct dentry *dentry = path->dentry;
@@ -278,7 +278,7 @@ out:
 	return err;
 }
 
-int ovl_permission(struct user_namespace *mnt_userns,
+int ovl_permission(struct mnt_idmap *idmap,
 		   struct inode *inode, int mask)
 {
 	struct inode *upperinode = ovl_inode_upper(inode);
@@ -298,7 +298,7 @@ int ovl_permission(struct user_namespace *mnt_userns,
 	 * Check overlay inode with the creds of task and underlying inode
 	 * with creds of mounter
 	 */
-	err = generic_permission(&init_user_ns, inode, mask);
+	err = generic_permission(&nop_mnt_idmap, inode, mask);
 	if (err)
 		return err;
 
@@ -310,7 +310,7 @@ int ovl_permission(struct user_namespace *mnt_userns,
 		/* Make sure mounter can read file for copy up later */
 		mask |= MAY_READ;
 	}
-	err = inode_permission(mnt_user_ns(realpath.mnt), realinode, mask);
+	err = inode_permission(mnt_idmap(realpath.mnt), realinode, mask);
 	revert_creds(old_cred);
 
 	return err;
@@ -361,7 +361,7 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
 	if (!value && !upperdentry) {
 		ovl_path_lower(dentry, &realpath);
 		old_cred = ovl_override_creds(dentry->d_sb);
-		err = vfs_getxattr(mnt_user_ns(realpath.mnt), realdentry, name, NULL, 0);
+		err = vfs_getxattr(mnt_idmap(realpath.mnt), realdentry, name, NULL, 0);
 		revert_creds(old_cred);
 		if (err < 0)
 			goto out_drop_write;
@@ -403,7 +403,7 @@ int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
 
 	ovl_i_path_real(inode, &realpath);
 	old_cred = ovl_override_creds(dentry->d_sb);
-	res = vfs_getxattr(mnt_user_ns(realpath.mnt), realpath.dentry, name, value, size);
+	res = vfs_getxattr(mnt_idmap(realpath.mnt), realpath.dentry, name, value, size);
 	revert_creds(old_cred);
 	return res;
 }
@@ -463,7 +463,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
  * alter the POSIX ACLs for the underlying filesystem.
  */
 static void ovl_idmap_posix_acl(const struct inode *realinode,
-				struct user_namespace *mnt_userns,
+				struct mnt_idmap *idmap,
 				struct posix_acl *acl)
 {
 	struct user_namespace *fs_userns = i_user_ns(realinode);
@@ -475,11 +475,11 @@ static void ovl_idmap_posix_acl(const struct inode *realinode,
 		struct posix_acl_entry *e = &acl->a_entries[i];
 		switch (e->e_tag) {
 		case ACL_USER:
-			vfsuid = make_vfsuid(mnt_userns, fs_userns, e->e_uid);
+			vfsuid = make_vfsuid(idmap, fs_userns, e->e_uid);
 			e->e_uid = vfsuid_into_kuid(vfsuid);
 			break;
 		case ACL_GROUP:
-			vfsgid = make_vfsgid(mnt_userns, fs_userns, e->e_gid);
+			vfsgid = make_vfsgid(idmap, fs_userns, e->e_gid);
 			e->e_gid = vfsgid_into_kgid(vfsgid);
 			break;
 		}
@@ -514,15 +514,15 @@ struct posix_acl *ovl_get_acl_path(const struct path *path,
 				   const char *acl_name, bool noperm)
 {
 	struct posix_acl *real_acl, *clone;
-	struct user_namespace *mnt_userns;
+	struct mnt_idmap *idmap;
 	struct inode *realinode = d_inode(path->dentry);
 
-	mnt_userns = mnt_user_ns(path->mnt);
+	idmap = mnt_idmap(path->mnt);
 
 	if (noperm)
 		real_acl = get_inode_acl(realinode, posix_acl_type(acl_name));
 	else
-		real_acl = vfs_get_acl(mnt_userns, path->dentry, acl_name);
+		real_acl = vfs_get_acl(idmap, path->dentry, acl_name);
 	if (IS_ERR_OR_NULL(real_acl))
 		return real_acl;
 
@@ -540,7 +540,7 @@ struct posix_acl *ovl_get_acl_path(const struct path *path,
 	if (!clone)
 		return ERR_PTR(-ENOMEM);
 
-	ovl_idmap_posix_acl(realinode, mnt_userns, clone);
+	ovl_idmap_posix_acl(realinode, idmap, clone);
 	return clone;
 }
 
@@ -555,7 +555,7 @@ struct posix_acl *ovl_get_acl_path(const struct path *path,
  *
  * This is obviously only relevant when idmapped layers are used.
  */
-struct posix_acl *do_ovl_get_acl(struct user_namespace *mnt_userns,
+struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
 				 struct inode *inode, int type,
 				 bool rcu, bool noperm)
 {
@@ -618,7 +618,7 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
 
 		ovl_path_lower(dentry, &realpath);
 		old_cred = ovl_override_creds(dentry->d_sb);
-		real_acl = vfs_get_acl(mnt_user_ns(realpath.mnt), realdentry,
+		real_acl = vfs_get_acl(mnt_idmap(realpath.mnt), realdentry,
 				       acl_name);
 		revert_creds(old_cred);
 		if (IS_ERR(real_acl)) {
@@ -651,7 +651,7 @@ out_drop_write:
 	return err;
 }
 
-int ovl_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+int ovl_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		struct posix_acl *acl, int type)
 {
 	int err;
@@ -665,7 +665,7 @@ int ovl_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
 		return -EOPNOTSUPP;
 	if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 		return acl ? -EACCES : 0;
-	if (!inode_owner_or_capable(&init_user_ns, inode))
+	if (!inode_owner_or_capable(&nop_mnt_idmap, inode))
 		return -EPERM;
 
 	/*
@@ -674,10 +674,10 @@ int ovl_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
 	 */
 	if (unlikely(inode->i_mode & S_ISGID) && type == ACL_TYPE_ACCESS &&
 	    !in_group_p(inode->i_gid) &&
-	    !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) {
+	    !capable_wrt_inode_uidgid(&nop_mnt_idmap, inode, CAP_FSETID)) {
 		struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
 
-		err = ovl_setattr(&init_user_ns, dentry, &iattr);
+		err = ovl_setattr(&nop_mnt_idmap, dentry, &iattr);
 		if (err)
 			return err;
 	}
@@ -755,10 +755,10 @@ int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa)
 	if (err)
 		return err;
 
-	return vfs_fileattr_set(mnt_user_ns(realpath->mnt), realpath->dentry, fa);
+	return vfs_fileattr_set(mnt_idmap(realpath->mnt), realpath->dentry, fa);
 }
 
-int ovl_fileattr_set(struct user_namespace *mnt_userns,
+int ovl_fileattr_set(struct mnt_idmap *idmap,
 		     struct dentry *dentry, struct fileattr *fa)
 {
 	struct inode *inode = d_inode(dentry);
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 46753134533a..cfb3420b7df0 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -204,7 +204,7 @@ static struct dentry *ovl_lookup_positive_unlocked(struct ovl_lookup_data *d,
 						   struct dentry *base, int len,
 						   bool drop_negative)
 {
-	struct dentry *ret = lookup_one_unlocked(mnt_user_ns(d->mnt), name, base, len);
+	struct dentry *ret = lookup_one_unlocked(mnt_idmap(d->mnt), name, base, len);
 
 	if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
 		if (drop_negative && ret->d_lockref.count == 1) {
@@ -711,7 +711,7 @@ struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
 	if (err)
 		return ERR_PTR(err);
 
-	index = lookup_one_positive_unlocked(ovl_upper_mnt_userns(ofs), name.name,
+	index = lookup_one_positive_unlocked(ovl_upper_mnt_idmap(ofs), name.name,
 					     ofs->indexdir, name.len);
 	if (IS_ERR(index)) {
 		err = PTR_ERR(index);
@@ -1182,7 +1182,7 @@ bool ovl_lower_positive(struct dentry *dentry)
 		struct dentry *this;
 		struct dentry *lowerdir = poe->lowerstack[i].dentry;
 
-		this = lookup_one_positive_unlocked(mnt_user_ns(poe->lowerstack[i].layer->mnt),
+		this = lookup_one_positive_unlocked(mnt_idmap(poe->lowerstack[i].layer->mnt),
 						   name->name, lowerdir, name->len);
 		if (IS_ERR(this)) {
 			switch (PTR_ERR(this)) {
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 1df7f850ff3b..4d0b278f5630 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -141,13 +141,13 @@ static inline int ovl_do_notify_change(struct ovl_fs *ofs,
 				       struct dentry *upperdentry,
 				       struct iattr *attr)
 {
-	return notify_change(ovl_upper_mnt_userns(ofs), upperdentry, attr, NULL);
+	return notify_change(ovl_upper_mnt_idmap(ofs), upperdentry, attr, NULL);
 }
 
 static inline int ovl_do_rmdir(struct ovl_fs *ofs,
 			       struct inode *dir, struct dentry *dentry)
 {
-	int err = vfs_rmdir(ovl_upper_mnt_userns(ofs), dir, dentry);
+	int err = vfs_rmdir(ovl_upper_mnt_idmap(ofs), dir, dentry);
 
 	pr_debug("rmdir(%pd2) = %i\n", dentry, err);
 	return err;
@@ -156,7 +156,7 @@ static inline int ovl_do_rmdir(struct ovl_fs *ofs,
 static inline int ovl_do_unlink(struct ovl_fs *ofs, struct inode *dir,
 				struct dentry *dentry)
 {
-	int err = vfs_unlink(ovl_upper_mnt_userns(ofs), dir, dentry, NULL);
+	int err = vfs_unlink(ovl_upper_mnt_idmap(ofs), dir, dentry, NULL);
 
 	pr_debug("unlink(%pd2) = %i\n", dentry, err);
 	return err;
@@ -165,7 +165,8 @@ static inline int ovl_do_unlink(struct ovl_fs *ofs, struct inode *dir,
 static inline int ovl_do_link(struct ovl_fs *ofs, struct dentry *old_dentry,
 			      struct inode *dir, struct dentry *new_dentry)
 {
-	int err = vfs_link(old_dentry, ovl_upper_mnt_userns(ofs), dir, new_dentry, NULL);
+	int err = vfs_link(old_dentry, ovl_upper_mnt_idmap(ofs), dir,
+			   new_dentry, NULL);
 
 	pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
 	return err;
@@ -175,7 +176,7 @@ static inline int ovl_do_create(struct ovl_fs *ofs,
 				struct inode *dir, struct dentry *dentry,
 				umode_t mode)
 {
-	int err = vfs_create(ovl_upper_mnt_userns(ofs), dir, dentry, mode, true);
+	int err = vfs_create(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, true);
 
 	pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
 	return err;
@@ -185,7 +186,7 @@ static inline int ovl_do_mkdir(struct ovl_fs *ofs,
 			       struct inode *dir, struct dentry *dentry,
 			       umode_t mode)
 {
-	int err = vfs_mkdir(ovl_upper_mnt_userns(ofs), dir, dentry, mode);
+	int err = vfs_mkdir(ovl_upper_mnt_idmap(ofs), dir, dentry, mode);
 	pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
 	return err;
 }
@@ -194,7 +195,7 @@ static inline int ovl_do_mknod(struct ovl_fs *ofs,
 			       struct inode *dir, struct dentry *dentry,
 			       umode_t mode, dev_t dev)
 {
-	int err = vfs_mknod(ovl_upper_mnt_userns(ofs), dir, dentry, mode, dev);
+	int err = vfs_mknod(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, dev);
 
 	pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
 	return err;
@@ -204,7 +205,7 @@ static inline int ovl_do_symlink(struct ovl_fs *ofs,
 				 struct inode *dir, struct dentry *dentry,
 				 const char *oldname)
 {
-	int err = vfs_symlink(ovl_upper_mnt_userns(ofs), dir, dentry, oldname);
+	int err = vfs_symlink(ovl_upper_mnt_idmap(ofs), dir, dentry, oldname);
 
 	pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
 	return err;
@@ -217,7 +218,7 @@ static inline ssize_t ovl_do_getxattr(const struct path *path, const char *name,
 
 	WARN_ON(path->dentry->d_sb != path->mnt->mnt_sb);
 
-	err = vfs_getxattr(mnt_user_ns(path->mnt), path->dentry,
+	err = vfs_getxattr(mnt_idmap(path->mnt), path->dentry,
 			       name, value, size);
 	len = (value && err > 0) ? err : 0;
 
@@ -251,7 +252,7 @@ static inline int ovl_do_setxattr(struct ovl_fs *ofs, struct dentry *dentry,
 				  const char *name, const void *value,
 				  size_t size, int flags)
 {
-	int err = vfs_setxattr(ovl_upper_mnt_userns(ofs), dentry, name,
+	int err = vfs_setxattr(ovl_upper_mnt_idmap(ofs), dentry, name,
 			       value, size, flags);
 
 	pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, %d) = %i\n",
@@ -269,7 +270,7 @@ static inline int ovl_setxattr(struct ovl_fs *ofs, struct dentry *dentry,
 static inline int ovl_do_removexattr(struct ovl_fs *ofs, struct dentry *dentry,
 				     const char *name)
 {
-	int err = vfs_removexattr(ovl_upper_mnt_userns(ofs), dentry, name);
+	int err = vfs_removexattr(ovl_upper_mnt_idmap(ofs), dentry, name);
 	pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
 	return err;
 }
@@ -283,13 +284,13 @@ static inline int ovl_removexattr(struct ovl_fs *ofs, struct dentry *dentry,
 static inline int ovl_do_set_acl(struct ovl_fs *ofs, struct dentry *dentry,
 				 const char *acl_name, struct posix_acl *acl)
 {
-	return vfs_set_acl(ovl_upper_mnt_userns(ofs), dentry, acl_name, acl);
+	return vfs_set_acl(ovl_upper_mnt_idmap(ofs), dentry, acl_name, acl);
 }
 
 static inline int ovl_do_remove_acl(struct ovl_fs *ofs, struct dentry *dentry,
 				    const char *acl_name)
 {
-	return vfs_remove_acl(ovl_upper_mnt_userns(ofs), dentry, acl_name);
+	return vfs_remove_acl(ovl_upper_mnt_idmap(ofs), dentry, acl_name);
 }
 
 static inline int ovl_do_rename(struct ovl_fs *ofs, struct inode *olddir,
@@ -298,10 +299,10 @@ static inline int ovl_do_rename(struct ovl_fs *ofs, struct inode *olddir,
 {
 	int err;
 	struct renamedata rd = {
-		.old_mnt_userns	= ovl_upper_mnt_userns(ofs),
+		.old_mnt_idmap	= ovl_upper_mnt_idmap(ofs),
 		.old_dir 	= olddir,
 		.old_dentry 	= olddentry,
-		.new_mnt_userns	= ovl_upper_mnt_userns(ofs),
+		.new_mnt_idmap	= ovl_upper_mnt_idmap(ofs),
 		.new_dir 	= newdir,
 		.new_dentry 	= newdentry,
 		.flags 		= flags,
@@ -319,7 +320,7 @@ static inline int ovl_do_rename(struct ovl_fs *ofs, struct inode *olddir,
 static inline int ovl_do_whiteout(struct ovl_fs *ofs,
 				  struct inode *dir, struct dentry *dentry)
 {
-	int err = vfs_whiteout(ovl_upper_mnt_userns(ofs), dir, dentry);
+	int err = vfs_whiteout(ovl_upper_mnt_idmap(ofs), dir, dentry);
 	pr_debug("whiteout(%pd2) = %i\n", dentry, err);
 	return err;
 }
@@ -328,7 +329,7 @@ static inline struct file *ovl_do_tmpfile(struct ovl_fs *ofs,
 					  struct dentry *dentry, umode_t mode)
 {
 	struct path path = { .mnt = ovl_upper_mnt(ofs), .dentry = dentry };
-	struct file *file = vfs_tmpfile_open(ovl_upper_mnt_userns(ofs), &path, mode,
+	struct file *file = vfs_tmpfile_open(ovl_upper_mnt_idmap(ofs), &path, mode,
 					O_LARGEFILE | O_WRONLY, current_cred());
 	int err = PTR_ERR_OR_ZERO(file);
 
@@ -340,7 +341,7 @@ static inline struct dentry *ovl_lookup_upper(struct ovl_fs *ofs,
 					      const char *name,
 					      struct dentry *base, int len)
 {
-	return lookup_one(ovl_upper_mnt_userns(ofs), name, base, len);
+	return lookup_one(ovl_upper_mnt_idmap(ofs), name, base, len);
 }
 
 static inline bool ovl_open_flags_need_copy_up(int flags)
@@ -596,11 +597,11 @@ int ovl_set_nlink_lower(struct dentry *dentry);
 unsigned int ovl_get_nlink(struct ovl_fs *ofs, struct dentry *lowerdentry,
 			   struct dentry *upperdentry,
 			   unsigned int fallback);
-int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		struct iattr *attr);
-int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
 		struct kstat *stat, u32 request_mask, unsigned int flags);
-int ovl_permission(struct user_namespace *mnt_userns, struct inode *inode,
+int ovl_permission(struct mnt_idmap *idmap, struct inode *inode,
 		   int mask);
 int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
 		  const void *value, size_t size, int flags);
@@ -609,20 +610,20 @@ int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
 
 #ifdef CONFIG_FS_POSIX_ACL
-struct posix_acl *do_ovl_get_acl(struct user_namespace *mnt_userns,
+struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
 				 struct inode *inode, int type,
 				 bool rcu, bool noperm);
 static inline struct posix_acl *ovl_get_inode_acl(struct inode *inode, int type,
 						  bool rcu)
 {
-	return do_ovl_get_acl(&init_user_ns, inode, type, rcu, true);
+	return do_ovl_get_acl(&nop_mnt_idmap, inode, type, rcu, true);
 }
-static inline struct posix_acl *ovl_get_acl(struct user_namespace *mnt_userns,
+static inline struct posix_acl *ovl_get_acl(struct mnt_idmap *idmap,
 					    struct dentry *dentry, int type)
 {
-	return do_ovl_get_acl(mnt_userns, d_inode(dentry), type, false, false);
+	return do_ovl_get_acl(idmap, d_inode(dentry), type, false, false);
 }
-int ovl_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+int ovl_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		struct posix_acl *acl, int type);
 struct posix_acl *ovl_get_acl_path(const struct path *path,
 				   const char *acl_name, bool noperm);
@@ -717,7 +718,7 @@ void ovl_aio_request_cache_destroy(void);
 int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa);
 int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa);
 int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa);
-int ovl_fileattr_set(struct user_namespace *mnt_userns,
+int ovl_fileattr_set(struct mnt_idmap *idmap,
 		     struct dentry *dentry, struct fileattr *fa);
 
 /* copy_up.c */
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index e1af8f660698..fd11fe6d6d45 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -90,9 +90,9 @@ static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
 	return ofs->layers[0].mnt;
 }
 
-static inline struct user_namespace *ovl_upper_mnt_userns(struct ovl_fs *ofs)
+static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs)
 {
-	return mnt_user_ns(ovl_upper_mnt(ofs));
+	return mnt_idmap(ovl_upper_mnt(ofs));
 }
 
 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 8cd2b9947de1..b6952b21a7ee 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -278,7 +278,7 @@ static int ovl_check_whiteouts(const struct path *path, struct ovl_readdir_data
 		while (rdd->first_maybe_whiteout) {
 			p = rdd->first_maybe_whiteout;
 			rdd->first_maybe_whiteout = p->next_maybe_whiteout;
-			dentry = lookup_one(mnt_user_ns(path->mnt), p->name, dir, p->len);
+			dentry = lookup_one(mnt_idmap(path->mnt), p->name, dir, p->len);
 			if (!IS_ERR(dentry)) {
 				p->is_whiteout = ovl_is_whiteout(dentry);
 				dput(dentry);
@@ -480,7 +480,7 @@ static int ovl_cache_update_ino(const struct path *path, struct ovl_cache_entry
 			goto get;
 		}
 	}
-	this = lookup_one(mnt_user_ns(path->mnt), p->name, dir, p->len);
+	this = lookup_one(mnt_idmap(path->mnt), p->name, dir, p->len);
 	if (IS_ERR_OR_NULL(this) || !this->d_inode) {
 		/* Mark a stale entry */
 		p->is_whiteout = true;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 85b891152a2c..f1d9f75f8786 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1012,7 +1012,7 @@ static int ovl_own_xattr_get(const struct xattr_handler *handler,
 }
 
 static int ovl_own_xattr_set(const struct xattr_handler *handler,
-			     struct user_namespace *mnt_userns,
+			     struct mnt_idmap *idmap,
 			     struct dentry *dentry, struct inode *inode,
 			     const char *name, const void *value,
 			     size_t size, int flags)
@@ -1028,7 +1028,7 @@ static int ovl_other_xattr_get(const struct xattr_handler *handler,
 }
 
 static int ovl_other_xattr_set(const struct xattr_handler *handler,
-			       struct user_namespace *mnt_userns,
+			       struct mnt_idmap *idmap,
 			       struct dentry *dentry, struct inode *inode,
 			       const char *name, const void *value,
 			       size_t size, int flags)
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index bde291623c8c..923d66d131c1 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -491,7 +491,7 @@ bool ovl_is_whiteout(struct dentry *dentry)
 struct file *ovl_path_open(const struct path *path, int flags)
 {
 	struct inode *inode = d_inode(path->dentry);
-	struct user_namespace *real_mnt_userns = mnt_user_ns(path->mnt);
+	struct mnt_idmap *real_idmap = mnt_idmap(path->mnt);
 	int err, acc_mode;
 
 	if (flags & ~(O_ACCMODE | O_LARGEFILE))
@@ -508,12 +508,12 @@ struct file *ovl_path_open(const struct path *path, int flags)
 		BUG();
 	}
 
-	err = inode_permission(real_mnt_userns, inode, acc_mode | MAY_OPEN);
+	err = inode_permission(real_idmap, inode, acc_mode | MAY_OPEN);
 	if (err)
 		return ERR_PTR(err);
 
 	/* O_NOATIME is an optimization, don't fail if not permitted */
-	if (inode_owner_or_capable(real_mnt_userns, inode))
+	if (inode_owner_or_capable(real_idmap, inode))
 		flags |= O_NOATIME;
 
 	return dentry_open(path, flags, current_cred());
@@ -1101,16 +1101,16 @@ void ovl_copyattr(struct inode *inode)
 {
 	struct path realpath;
 	struct inode *realinode;
-	struct user_namespace *real_mnt_userns;
+	struct mnt_idmap *real_idmap;
 	vfsuid_t vfsuid;
 	vfsgid_t vfsgid;
 
 	ovl_i_path_real(inode, &realpath);
 	realinode = d_inode(realpath.dentry);
-	real_mnt_userns = mnt_user_ns(realpath.mnt);
+	real_idmap = mnt_idmap(realpath.mnt);
 
-	vfsuid = i_uid_into_vfsuid(real_mnt_userns, realinode);
-	vfsgid = i_gid_into_vfsgid(real_mnt_userns, realinode);
+	vfsuid = i_uid_into_vfsuid(real_idmap, realinode);
+	vfsgid = i_gid_into_vfsgid(real_idmap, realinode);
 
 	inode->i_uid = vfsuid_into_kuid(vfsuid);
 	inode->i_gid = vfsgid_into_kgid(vfsgid);