Merge tag 'vfs.misc.fixes.v6.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping

Pull vfs fix from Christian Brauner:
 "When a mount or mount tree is made shared the vfs allocates new peer
  group ids for all mounts that have no peer group id set. Only mounts
  that aren't marked with MNT_SHARED are relevant here as MNT_SHARED
  indicates that the mount has fully transitioned to a shared mount. The
  peer group id handling is done with namespace lock held.

  On failure, the peer group id settings of mounts for which a new peer
  group id was allocated need to be reverted and the allocated peer
  group id freed. The cleanup_group_ids() helper can identify the mounts
  to cleanup by checking whether a given mount has a peer group id set
  but isn't marked MNT_SHARED. The deallocation always needs to happen
  with namespace lock held to protect against concurrent modifications
  of the propagation settings.

  This fixes the one place where the namespace lock was dropped before
  calling cleanup_group_ids()"

* tag 'vfs.misc.fixes.v6.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping:
  fs: drop peer group ids under namespace lock

Author: torvalds

fs/namespace.c

@@ -4183,9 +4183,9 @@ static int do_mount_setattr(struct path *path, struct mount_kattr *kattr)
 	unlock_mount_hash();
 
 	if (kattr->propagation) {
-		namespace_unlock();
 		if (err)
 			cleanup_group_ids(mnt, NULL);
+		namespace_unlock();
 	}
 
 	return err;