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
  ...

4 files changed, 15 insertions, 15 deletions

diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 232dd7b6cca14..1310d2d5feb38 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -364,7 +364,7 @@ struct inode *nilfs_new_inode(struct inode *dir, umode_t mode)
 	ii->i_bh = bh;
 
 	atomic64_inc(&root->inodes_count);
-	inode_init_owner(&init_user_ns, inode, dir, mode);
+	inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
 	inode->i_ino = ino;
 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 
@@ -949,7 +949,7 @@ void nilfs_evict_inode(struct inode *inode)
 	 */
 }
 
-int nilfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+int nilfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		  struct iattr *iattr)
 {
 	struct nilfs_transaction_info ti;
@@ -957,7 +957,7 @@ int nilfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 	struct super_block *sb = inode->i_sb;
 	int err;
 
-	err = setattr_prepare(&init_user_ns, dentry, iattr);
+	err = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
 	if (err)
 		return err;
 
@@ -972,7 +972,7 @@ int nilfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 		nilfs_truncate(inode);
 	}
 
-	setattr_copy(&init_user_ns, inode, iattr);
+	setattr_copy(&nop_mnt_idmap, inode, iattr);
 	mark_inode_dirty(inode);
 
 	if (iattr->ia_valid & ATTR_MODE) {
@@ -988,7 +988,7 @@ out_err:
 	return err;
 }
 
-int nilfs_permission(struct user_namespace *mnt_userns, struct inode *inode,
+int nilfs_permission(struct mnt_idmap *idmap, struct inode *inode,
 		     int mask)
 {
 	struct nilfs_root *root = NILFS_I(inode)->i_root;
@@ -997,7 +997,7 @@ int nilfs_permission(struct user_namespace *mnt_userns, struct inode *inode,
 	    root->cno != NILFS_CPTREE_CURRENT_CNO)
 		return -EROFS; /* snapshot is not writable */
 
-	return generic_permission(&init_user_ns, inode, mask);
+	return generic_permission(&nop_mnt_idmap, inode, mask);
 }
 
 int nilfs_load_inode_block(struct inode *inode, struct buffer_head **pbh)
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index b4041d0566a9a..5ccc638ae92f7 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -128,7 +128,7 @@ int nilfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 /**
  * nilfs_fileattr_set - ioctl to support chattr
  */
-int nilfs_fileattr_set(struct user_namespace *mnt_userns,
+int nilfs_fileattr_set(struct mnt_idmap *idmap,
 		       struct dentry *dentry, struct fileattr *fa)
 {
 	struct inode *inode = d_inode(dentry);
diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
index 23899e0ae8509..c7024da8f1e25 100644
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -72,7 +72,7 @@ nilfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
  * If the create succeeds, we fill in the inode information
  * with d_instantiate().
  */
-static int nilfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int nilfs_create(struct mnt_idmap *idmap, struct inode *dir,
 			struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct inode *inode;
@@ -100,7 +100,7 @@ static int nilfs_create(struct user_namespace *mnt_userns, struct inode *dir,
 }
 
 static int
-nilfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+nilfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
 	    struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	struct inode *inode;
@@ -125,7 +125,7 @@ nilfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 	return err;
 }
 
-static int nilfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+static int nilfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 			 struct dentry *dentry, const char *symname)
 {
 	struct nilfs_transaction_info ti;
@@ -202,7 +202,7 @@ static int nilfs_link(struct dentry *old_dentry, struct inode *dir,
 	return err;
 }
 
-static int nilfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+static int nilfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode)
 {
 	struct inode *inode;
@@ -340,7 +340,7 @@ static int nilfs_rmdir(struct inode *dir, struct dentry *dentry)
 	return err;
 }
 
-static int nilfs_rename(struct user_namespace *mnt_userns,
+static int nilfs_rename(struct mnt_idmap *idmap,
 			struct inode *old_dir, struct dentry *old_dentry,
 			struct inode *new_dir, struct dentry *new_dentry,
 			unsigned int flags)
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index aecda4fc95f5f..8046490cd7fea 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -242,7 +242,7 @@ extern int nilfs_sync_file(struct file *, loff_t, loff_t, int);
 
 /* ioctl.c */
 int nilfs_fileattr_get(struct dentry *dentry, struct fileattr *m);
-int nilfs_fileattr_set(struct user_namespace *mnt_userns,
+int nilfs_fileattr_set(struct mnt_idmap *idmap,
 		       struct dentry *dentry, struct fileattr *fa);
 long nilfs_ioctl(struct file *, unsigned int, unsigned long);
 long nilfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
@@ -271,10 +271,10 @@ struct inode *nilfs_iget_for_shadow(struct inode *inode);
 extern void nilfs_update_inode(struct inode *, struct buffer_head *, int);
 extern void nilfs_truncate(struct inode *);
 extern void nilfs_evict_inode(struct inode *);
-extern int nilfs_setattr(struct user_namespace *, struct dentry *,
+extern int nilfs_setattr(struct mnt_idmap *, struct dentry *,
 			 struct iattr *);
 extern void nilfs_write_failed(struct address_space *mapping, loff_t to);
-int nilfs_permission(struct user_namespace *mnt_userns, struct inode *inode,
+int nilfs_permission(struct mnt_idmap *idmap, struct inode *inode,
 		     int mask);
 int nilfs_load_inode_block(struct inode *inode, struct buffer_head **pbh);
 extern int nilfs_inode_dirty(struct inode *);