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
  ...

8 files changed, 69 insertions, 69 deletions

diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 3da1779e8b79..7427449a04a3 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -110,7 +110,7 @@ out:
 	return ret;
 }
 
-int btrfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+int btrfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		  struct posix_acl *acl, int type)
 {
 	int ret;
@@ -118,7 +118,7 @@ int btrfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
 	umode_t old_mode = inode->i_mode;
 
 	if (type == ACL_TYPE_ACCESS && acl) {
-		ret = posix_acl_update_mode(mnt_userns, inode,
+		ret = posix_acl_update_mode(idmap, inode,
 					    &inode->i_mode, &acl);
 		if (ret)
 			return ret;
diff --git a/fs/btrfs/acl.h b/fs/btrfs/acl.h
index 39bd36e6eeb7..a270e71ec05f 100644
--- a/fs/btrfs/acl.h
+++ b/fs/btrfs/acl.h
@@ -6,7 +6,7 @@
 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 
 struct posix_acl *btrfs_get_acl(struct inode *inode, int type, bool rcu);
-int btrfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+int btrfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		  struct posix_acl *acl, int type);
 int __btrfs_set_acl(struct btrfs_trans_handle *trans, struct inode *inode,
 		    struct posix_acl *acl, int type);
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 195c09e20609..7c1527fcc7b3 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -469,7 +469,7 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
 int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
 			   struct btrfs_new_inode_args *args);
 void btrfs_new_inode_args_destroy(struct btrfs_new_inode_args *args);
-struct inode *btrfs_new_subvol_inode(struct user_namespace *mnt_userns,
+struct inode *btrfs_new_subvol_inode(struct mnt_idmap *idmap,
 				     struct inode *dir);
  void btrfs_set_delalloc_extent(struct btrfs_inode *inode, struct extent_state *state,
 			        u32 bits);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 98a800b8bd43..efee6d35af52 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5281,7 +5281,7 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr)
 	return ret;
 }
 
-static int btrfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+static int btrfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 			 struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
@@ -5291,7 +5291,7 @@ static int btrfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentr
 	if (btrfs_root_readonly(root))
 		return -EROFS;
 
-	err = setattr_prepare(mnt_userns, dentry, attr);
+	err = setattr_prepare(idmap, dentry, attr);
 	if (err)
 		return err;
 
@@ -5302,12 +5302,12 @@ static int btrfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentr
 	}
 
 	if (attr->ia_valid) {
-		setattr_copy(mnt_userns, inode, attr);
+		setattr_copy(idmap, inode, attr);
 		inode_inc_iversion(inode);
 		err = btrfs_dirty_inode(BTRFS_I(inode));
 
 		if (!err && attr->ia_valid & ATTR_MODE)
-			err = posix_acl_chmod(mnt_userns, dentry, inode->i_mode);
+			err = posix_acl_chmod(idmap, dentry, inode->i_mode);
 	}
 
 	return err;
@@ -6724,7 +6724,7 @@ out_inode:
 	return err;
 }
 
-static int btrfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+static int btrfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	struct inode *inode;
@@ -6732,13 +6732,13 @@ static int btrfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 	inode = new_inode(dir->i_sb);
 	if (!inode)
 		return -ENOMEM;
-	inode_init_owner(mnt_userns, inode, dir, mode);
+	inode_init_owner(idmap, inode, dir, mode);
 	inode->i_op = &btrfs_special_inode_operations;
 	init_special_inode(inode, inode->i_mode, rdev);
 	return btrfs_create_common(dir, dentry, inode);
 }
 
-static int btrfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int btrfs_create(struct mnt_idmap *idmap, struct inode *dir,
 			struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct inode *inode;
@@ -6746,7 +6746,7 @@ static int btrfs_create(struct user_namespace *mnt_userns, struct inode *dir,
 	inode = new_inode(dir->i_sb);
 	if (!inode)
 		return -ENOMEM;
-	inode_init_owner(mnt_userns, inode, dir, mode);
+	inode_init_owner(idmap, inode, dir, mode);
 	inode->i_fop = &btrfs_file_operations;
 	inode->i_op = &btrfs_file_inode_operations;
 	inode->i_mapping->a_ops = &btrfs_aops;
@@ -6837,7 +6837,7 @@ fail:
 	return err;
 }
 
-static int btrfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+static int btrfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode)
 {
 	struct inode *inode;
@@ -6845,7 +6845,7 @@ static int btrfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 	inode = new_inode(dir->i_sb);
 	if (!inode)
 		return -ENOMEM;
-	inode_init_owner(mnt_userns, inode, dir, S_IFDIR | mode);
+	inode_init_owner(idmap, inode, dir, S_IFDIR | mode);
 	inode->i_op = &btrfs_dir_inode_operations;
 	inode->i_fop = &btrfs_dir_file_operations;
 	return btrfs_create_common(dir, dentry, inode);
@@ -8802,7 +8802,7 @@ out:
 	return ret;
 }
 
-struct inode *btrfs_new_subvol_inode(struct user_namespace *mnt_userns,
+struct inode *btrfs_new_subvol_inode(struct mnt_idmap *idmap,
 				     struct inode *dir)
 {
 	struct inode *inode;
@@ -8813,7 +8813,7 @@ struct inode *btrfs_new_subvol_inode(struct user_namespace *mnt_userns,
 		 * Subvolumes don't inherit the sgid bit or the parent's gid if
 		 * the parent's sgid bit is set. This is probably a bug.
 		 */
-		inode_init_owner(mnt_userns, inode, NULL,
+		inode_init_owner(idmap, inode, NULL,
 				 S_IFDIR | (~current_umask() & S_IRWXUGO));
 		inode->i_op = &btrfs_dir_inode_operations;
 		inode->i_fop = &btrfs_dir_file_operations;
@@ -9004,7 +9004,7 @@ fail:
 	return -ENOMEM;
 }
 
-static int btrfs_getattr(struct user_namespace *mnt_userns,
+static int btrfs_getattr(struct mnt_idmap *idmap,
 			 const struct path *path, struct kstat *stat,
 			 u32 request_mask, unsigned int flags)
 {
@@ -9034,7 +9034,7 @@ static int btrfs_getattr(struct user_namespace *mnt_userns,
 				  STATX_ATTR_IMMUTABLE |
 				  STATX_ATTR_NODUMP);
 
-	generic_fillattr(mnt_userns, inode, stat);
+	generic_fillattr(idmap, inode, stat);
 	stat->dev = BTRFS_I(inode)->root->anon_dev;
 
 	spin_lock(&BTRFS_I(inode)->lock);
@@ -9289,14 +9289,14 @@ out_notrans:
 	return ret;
 }
 
-static struct inode *new_whiteout_inode(struct user_namespace *mnt_userns,
+static struct inode *new_whiteout_inode(struct mnt_idmap *idmap,
 					struct inode *dir)
 {
 	struct inode *inode;
 
 	inode = new_inode(dir->i_sb);
 	if (inode) {
-		inode_init_owner(mnt_userns, inode, dir,
+		inode_init_owner(idmap, inode, dir,
 				 S_IFCHR | WHITEOUT_MODE);
 		inode->i_op = &btrfs_special_inode_operations;
 		init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
@@ -9304,7 +9304,7 @@ static struct inode *new_whiteout_inode(struct user_namespace *mnt_userns,
 	return inode;
 }
 
-static int btrfs_rename(struct user_namespace *mnt_userns,
+static int btrfs_rename(struct mnt_idmap *idmap,
 			struct inode *old_dir, struct dentry *old_dentry,
 			struct inode *new_dir, struct dentry *new_dentry,
 			unsigned int flags)
@@ -9376,7 +9376,7 @@ static int btrfs_rename(struct user_namespace *mnt_userns,
 		filemap_flush(old_inode->i_mapping);
 
 	if (flags & RENAME_WHITEOUT) {
-		whiteout_args.inode = new_whiteout_inode(mnt_userns, old_dir);
+		whiteout_args.inode = new_whiteout_inode(idmap, old_dir);
 		if (!whiteout_args.inode) {
 			ret = -ENOMEM;
 			goto out_fscrypt_names;
@@ -9545,7 +9545,7 @@ out_fscrypt_names:
 	return ret;
 }
 
-static int btrfs_rename2(struct user_namespace *mnt_userns, struct inode *old_dir,
+static int btrfs_rename2(struct mnt_idmap *idmap, struct inode *old_dir,
 			 struct dentry *old_dentry, struct inode *new_dir,
 			 struct dentry *new_dentry, unsigned int flags)
 {
@@ -9558,7 +9558,7 @@ static int btrfs_rename2(struct user_namespace *mnt_userns, struct inode *old_di
 		ret = btrfs_rename_exchange(old_dir, old_dentry, new_dir,
 					    new_dentry);
 	else
-		ret = btrfs_rename(mnt_userns, old_dir, old_dentry, new_dir,
+		ret = btrfs_rename(idmap, old_dir, old_dentry, new_dir,
 				   new_dentry, flags);
 
 	btrfs_btree_balance_dirty(BTRFS_I(new_dir)->root->fs_info);
@@ -9758,7 +9758,7 @@ out:
 	return ret;
 }
 
-static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+static int btrfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 			 struct dentry *dentry, const char *symname)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
@@ -9786,7 +9786,7 @@ static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 	inode = new_inode(dir->i_sb);
 	if (!inode)
 		return -ENOMEM;
-	inode_init_owner(mnt_userns, inode, dir, S_IFLNK | S_IRWXUGO);
+	inode_init_owner(idmap, inode, dir, S_IFLNK | S_IRWXUGO);
 	inode->i_op = &btrfs_symlink_inode_operations;
 	inode_nohighmem(inode);
 	inode->i_mapping->a_ops = &btrfs_aops;
@@ -10075,7 +10075,7 @@ int btrfs_prealloc_file_range_trans(struct inode *inode,
 					   min_size, actual_len, alloc_hint, trans);
 }
 
-static int btrfs_permission(struct user_namespace *mnt_userns,
+static int btrfs_permission(struct mnt_idmap *idmap,
 			    struct inode *inode, int mask)
 {
 	struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -10088,10 +10088,10 @@ static int btrfs_permission(struct user_namespace *mnt_userns,
 		if (BTRFS_I(inode)->flags & BTRFS_INODE_READONLY)
 			return -EACCES;
 	}
-	return generic_permission(mnt_userns, inode, mask);
+	return generic_permission(idmap, inode, mask);
 }
 
-static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
+static int btrfs_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
 			 struct file *file, umode_t mode)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
@@ -10109,7 +10109,7 @@ static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	inode = new_inode(dir->i_sb);
 	if (!inode)
 		return -ENOMEM;
-	inode_init_owner(mnt_userns, inode, dir, mode);
+	inode_init_owner(idmap, inode, dir, mode);
 	inode->i_fop = &btrfs_file_operations;
 	inode->i_op = &btrfs_file_inode_operations;
 	inode->i_mapping->a_ops = &btrfs_aops;
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 7e348bd2ccde..5ba1ff31713b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -243,7 +243,7 @@ int btrfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 	return 0;
 }
 
-int btrfs_fileattr_set(struct user_namespace *mnt_userns,
+int btrfs_fileattr_set(struct mnt_idmap *idmap,
 		       struct dentry *dentry, struct fileattr *fa)
 {
 	struct inode *inode = d_inode(dentry);
@@ -578,7 +578,7 @@ static unsigned int create_subvol_num_items(struct btrfs_qgroup_inherit *inherit
 	return num_items;
 }
 
-static noinline int create_subvol(struct user_namespace *mnt_userns,
+static noinline int create_subvol(struct mnt_idmap *idmap,
 				  struct inode *dir, struct dentry *dentry,
 				  struct btrfs_qgroup_inherit *inherit)
 {
@@ -623,7 +623,7 @@ static noinline int create_subvol(struct user_namespace *mnt_userns,
 	if (ret < 0)
 		goto out_root_item;
 
-	new_inode_args.inode = btrfs_new_subvol_inode(mnt_userns, dir);
+	new_inode_args.inode = btrfs_new_subvol_inode(idmap, dir);
 	if (!new_inode_args.inode) {
 		ret = -ENOMEM;
 		goto out_anon_dev;
@@ -898,7 +898,7 @@ free_pending:
  *     nfs_async_unlink().
  */
 
-static int btrfs_may_delete(struct user_namespace *mnt_userns,
+static int btrfs_may_delete(struct mnt_idmap *idmap,
 			    struct inode *dir, struct dentry *victim, int isdir)
 {
 	int error;
@@ -909,12 +909,12 @@ static int btrfs_may_delete(struct user_namespace *mnt_userns,
 	BUG_ON(d_inode(victim->d_parent) != dir);
 	audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
 
-	error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
+	error = inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC);
 	if (error)
 		return error;
 	if (IS_APPEND(dir))
 		return -EPERM;
-	if (check_sticky(mnt_userns, dir, d_inode(victim)) ||
+	if (check_sticky(idmap, dir, d_inode(victim)) ||
 	    IS_APPEND(d_inode(victim)) || IS_IMMUTABLE(d_inode(victim)) ||
 	    IS_SWAPFILE(d_inode(victim)))
 		return -EPERM;
@@ -933,16 +933,16 @@ static int btrfs_may_delete(struct user_namespace *mnt_userns,
 }
 
 /* copy of may_create in fs/namei.c() */
-static inline int btrfs_may_create(struct user_namespace *mnt_userns,
+static inline int btrfs_may_create(struct mnt_idmap *idmap,
 				   struct inode *dir, struct dentry *child)
 {
 	if (d_really_is_positive(child))
 		return -EEXIST;
 	if (IS_DEADDIR(dir))
 		return -ENOENT;
-	if (!fsuidgid_has_mapping(dir->i_sb, mnt_userns))
+	if (!fsuidgid_has_mapping(dir->i_sb, idmap))
 		return -EOVERFLOW;
-	return inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
+	return inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC);
 }
 
 /*
@@ -951,7 +951,7 @@ static inline int btrfs_may_create(struct user_namespace *mnt_userns,
  * inside this filesystem so it's quite a bit simpler.
  */
 static noinline int btrfs_mksubvol(const struct path *parent,
-				   struct user_namespace *mnt_userns,
+				   struct mnt_idmap *idmap,
 				   const char *name, int namelen,
 				   struct btrfs_root *snap_src,
 				   bool readonly,
@@ -967,12 +967,12 @@ static noinline int btrfs_mksubvol(const struct path *parent,
 	if (error == -EINTR)
 		return error;
 
-	dentry = lookup_one(mnt_userns, name, parent->dentry, namelen);
+	dentry = lookup_one(idmap, name, parent->dentry, namelen);
 	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
 		goto out_unlock;
 
-	error = btrfs_may_create(mnt_userns, dir, dentry);
+	error = btrfs_may_create(idmap, dir, dentry);
 	if (error)
 		goto out_dput;
 
@@ -993,7 +993,7 @@ static noinline int btrfs_mksubvol(const struct path *parent,
 	if (snap_src)
 		error = create_snapshot(snap_src, dir, dentry, readonly, inherit);
 	else
-		error = create_subvol(mnt_userns, dir, dentry, inherit);
+		error = create_subvol(idmap, dir, dentry, inherit);
 
 	if (!error)
 		fsnotify_mkdir(dir, dentry);
@@ -1007,7 +1007,7 @@ out_unlock:
 }
 
 static noinline int btrfs_mksnapshot(const struct path *parent,
-				   struct user_namespace *mnt_userns,
+				   struct mnt_idmap *idmap,
 				   const char *name, int namelen,
 				   struct btrfs_root *root,
 				   bool readonly,
@@ -1037,7 +1037,7 @@ static noinline int btrfs_mksnapshot(const struct path *parent,
 
 	btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
 
-	ret = btrfs_mksubvol(parent, mnt_userns, name, namelen,
+	ret = btrfs_mksubvol(parent, idmap, name, namelen,
 			     root, readonly, inherit);
 out:
 	if (snapshot_force_cow)
@@ -1240,7 +1240,7 @@ out_drop:
 }
 
 static noinline int __btrfs_ioctl_snap_create(struct file *file,
-				struct user_namespace *mnt_userns,
+				struct mnt_idmap *idmap,
 				const char *name, unsigned long fd, int subvol,
 				bool readonly,
 				struct btrfs_qgroup_inherit *inherit)
@@ -1268,7 +1268,7 @@ static noinline int __btrfs_ioctl_snap_create(struct file *file,
 	}
 
 	if (subvol) {
-		ret = btrfs_mksubvol(&file->f_path, mnt_userns, name,
+		ret = btrfs_mksubvol(&file->f_path, idmap, name,
 				     namelen, NULL, readonly, inherit);
 	} else {
 		struct fd src = fdget(fd);
@@ -1283,14 +1283,14 @@ static noinline int __btrfs_ioctl_snap_create(struct file *file,
 			btrfs_info(BTRFS_I(file_inode(file))->root->fs_info,
 				   "Snapshot src from another FS");
 			ret = -EXDEV;
-		} else if (!inode_owner_or_capable(mnt_userns, src_inode)) {
+		} else if (!inode_owner_or_capable(idmap, src_inode)) {
 			/*
 			 * Subvolume creation is not restricted, but snapshots
 			 * are limited to own subvolumes only
 			 */
 			ret = -EPERM;
 		} else {
-			ret = btrfs_mksnapshot(&file->f_path, mnt_userns,
+			ret = btrfs_mksnapshot(&file->f_path, idmap,
 					       name, namelen,
 					       BTRFS_I(src_inode)->root,
 					       readonly, inherit);
@@ -1317,7 +1317,7 @@ static noinline int btrfs_ioctl_snap_create(struct file *file,
 		return PTR_ERR(vol_args);
 	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
 
-	ret = __btrfs_ioctl_snap_create(file, file_mnt_user_ns(file),
+	ret = __btrfs_ioctl_snap_create(file, file_mnt_idmap(file),
 					vol_args->name, vol_args->fd, subvol,
 					false, NULL);
 
@@ -1377,7 +1377,7 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
 		}
 	}
 
-	ret = __btrfs_ioctl_snap_create(file, file_mnt_user_ns(file),
+	ret = __btrfs_ioctl_snap_create(file, file_mnt_idmap(file),
 					vol_args->name, vol_args->fd, subvol,
 					readonly, inherit);
 	if (ret)
@@ -1422,7 +1422,7 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
 	u64 flags;
 	int ret = 0;
 
-	if (!inode_owner_or_capable(file_mnt_user_ns(file), inode))
+	if (!inode_owner_or_capable(file_mnt_idmap(file), inode))
 		return -EPERM;
 
 	ret = mnt_want_write_file(file);
@@ -1870,7 +1870,7 @@ out:
 	return ret;
 }
 
-static int btrfs_search_path_in_tree_user(struct user_namespace *mnt_userns,
+static int btrfs_search_path_in_tree_user(struct mnt_idmap *idmap,
 				struct inode *inode,
 				struct btrfs_ioctl_ino_lookup_user_args *args)
 {
@@ -1962,7 +1962,7 @@ static int btrfs_search_path_in_tree_user(struct user_namespace *mnt_userns,
 				ret = PTR_ERR(temp_inode);
 				goto out_put;
 			}
-			ret = inode_permission(mnt_userns, temp_inode,
+			ret = inode_permission(idmap, temp_inode,
 					       MAY_READ | MAY_EXEC);
 			iput(temp_inode);
 			if (ret) {
@@ -2101,7 +2101,7 @@ static int btrfs_ioctl_ino_lookup_user(struct file *file, void __user *argp)
 		return -EACCES;
 	}
 
-	ret = btrfs_search_path_in_tree_user(file_mnt_user_ns(file), inode, args);
+	ret = btrfs_search_path_in_tree_user(file_mnt_idmap(file), inode, args);
 
 	if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
 		ret = -EFAULT;
@@ -2335,7 +2335,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 	struct btrfs_root *dest = NULL;
 	struct btrfs_ioctl_vol_args *vol_args = NULL;
 	struct btrfs_ioctl_vol_args_v2 *vol_args2 = NULL;
-	struct user_namespace *mnt_userns = file_mnt_user_ns(file);
+	struct mnt_idmap *idmap = file_mnt_idmap(file);
 	char *subvol_name, *subvol_name_ptr = NULL;
 	int subvol_namelen;
 	int err = 0;
@@ -2428,7 +2428,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 			 * anywhere in the filesystem the user wouldn't be able
 			 * to delete without an idmapped mount.
 			 */
-			if (old_dir != dir && mnt_userns != &init_user_ns) {
+			if (old_dir != dir && idmap != &nop_mnt_idmap) {
 				err = -EOPNOTSUPP;
 				goto free_parent;
 			}
@@ -2471,7 +2471,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 	err = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
 	if (err == -EINTR)
 		goto free_subvol_name;
-	dentry = lookup_one(mnt_userns, subvol_name, parent, subvol_namelen);
+	dentry = lookup_one(idmap, subvol_name, parent, subvol_namelen);
 	if (IS_ERR(dentry)) {
 		err = PTR_ERR(dentry);
 		goto out_unlock_dir;
@@ -2513,13 +2513,13 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 		if (root == dest)
 			goto out_dput;
 
-		err = inode_permission(mnt_userns, inode, MAY_WRITE | MAY_EXEC);
+		err = inode_permission(idmap, inode, MAY_WRITE | MAY_EXEC);
 		if (err)
 			goto out_dput;
 	}
 
 	/* check if subvolume may be deleted by a user */
-	err = btrfs_may_delete(mnt_userns, dir, dentry, 1);
+	err = btrfs_may_delete(idmap, dir, dentry, 1);
 	if (err)
 		goto out_dput;
 
@@ -2582,7 +2582,7 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
 		 * running and allows defrag on files open in read-only mode.
 		 */
 		if (!capable(CAP_SYS_ADMIN) &&
-		    inode_permission(&init_user_ns, inode, MAY_WRITE)) {
+		    inode_permission(&nop_mnt_idmap, inode, MAY_WRITE)) {
 			ret = -EPERM;
 			goto out;
 		}
@@ -3907,7 +3907,7 @@ static long btrfs_ioctl_quota_rescan_wait(struct btrfs_fs_info *fs_info,
 }
 
 static long _btrfs_ioctl_set_received_subvol(struct file *file,
-					    struct user_namespace *mnt_userns,
+					    struct mnt_idmap *idmap,
 					    struct btrfs_ioctl_received_subvol_args *sa)
 {
 	struct inode *inode = file_inode(file);
@@ -3919,7 +3919,7 @@ static long _btrfs_ioctl_set_received_subvol(struct file *file,
 	int ret = 0;
 	int received_uuid_changed;
 
-	if (!inode_owner_or_capable(mnt_userns, inode))
+	if (!inode_owner_or_capable(idmap, inode))
 		return -EPERM;
 
 	ret = mnt_want_write_file(file);
@@ -4024,7 +4024,7 @@ static long btrfs_ioctl_set_received_subvol_32(struct file *file,
 	args64->rtime.nsec = args32->rtime.nsec;
 	args64->flags = args32->flags;
 
-	ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_user_ns(file), args64);
+	ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_idmap(file), args64);
 	if (ret)
 		goto out;
 
@@ -4058,7 +4058,7 @@ static long btrfs_ioctl_set_received_subvol(struct file *file,
 	if (IS_ERR(sa))
 		return PTR_ERR(sa);
 
-	ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_user_ns(file), sa);
+	ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_idmap(file), sa);
 
 	if (ret)
 		goto out;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 8a855d5ac2fa..d51b9a2f2f6e 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -6,7 +6,7 @@
 long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 long btrfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 int btrfs_fileattr_get(struct dentry *dentry, struct fileattr *fa);
-int btrfs_fileattr_set(struct user_namespace *mnt_userns,
+int btrfs_fileattr_set(struct mnt_idmap *idmap,
 		       struct dentry *dentry, struct fileattr *fa);
 int btrfs_ioctl_get_supported_features(void __user *arg);
 void btrfs_sync_inode_flags_to_i_flags(struct inode *inode);
diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
index 181469fc0bb3..ca09cf9afce8 100644
--- a/fs/btrfs/tests/btrfs-tests.c
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -64,7 +64,7 @@ struct inode *btrfs_new_test_inode(void)
 	BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY;
 	BTRFS_I(inode)->location.objectid = BTRFS_FIRST_FREE_OBJECTID;
 	BTRFS_I(inode)->location.offset = 0;
-	inode_init_owner(&init_user_ns, inode, NULL, S_IFREG);
+	inode_init_owner(&nop_mnt_idmap, inode, NULL, S_IFREG);
 
 	return inode;
 }
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 0ed4b119a7ca..0ebeaf4e81f9 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -370,7 +370,7 @@ static int btrfs_xattr_handler_get(const struct xattr_handler *handler,
 }
 
 static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
-				   struct user_namespace *mnt_userns,
+				   struct mnt_idmap *idmap,
 				   struct dentry *unused, struct inode *inode,
 				   const char *name, const void *buffer,
 				   size_t size, int flags)
@@ -383,7 +383,7 @@ static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
 }
 
 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
-					struct user_namespace *mnt_userns,
+					struct mnt_idmap *idmap,
 					struct dentry *unused, struct inode *inode,
 					const char *name, const void *value,
 					size_t size, int flags)