Merge tag 'fs.vfsuid.fat.v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping

Pull fatfs vfsuid conversion from Christian Brauner:
 "Last cycle we introduced the new vfs{g,u}id_t types that we had agreed
  on. The most important parts of the vfs have been converted but there
  are a few more places we need to switch before we can remove the old
  helpers completely.

  This cycle we converted all filesystems that called idmapped mount
  helpers directly. The affected filesystems are f2fs, fat, fuse, ksmbd,
  overlayfs, and xfs. We've sent patches for all of them. Looking at
  -next f2fs, ksmbd, overlayfs, and xfs have all picked up these patches
  and they should land in mainline during the v6.1 merge window.

  So all filesystems that have a separate tree should send the vfsuid
  conversion themselves. Onle the fat conversion is going through this
  generic fs trees because there is no fat tree.

  In order to change time settings on an inode fat checks that the
  caller either is the owner of the inode or the inode's group is in the
  caller's group list. If fat is on an idmapped mount we compare whether
  the inode mapped into the mount is equivalent to the caller's fsuid.
  If it isn't we compare whether the inode's group mapped into the mount
  is in the caller's group list.

  We now use the new vfsuid based helpers for that"

* tag 'fs.vfsuid.fat.v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping:
  fat: port to vfs{g,u}id_t and associated helpers

fs/fat/file.c

@@ -461,8 +461,9 @@ static int fat_allow_set_time(struct user_namespace *mnt_userns,
 {
 	umode_t allow_utime = sbi->options.allow_utime;
 
-	if (!uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode))) {
-		if (in_group_p(i_gid_into_mnt(mnt_userns, inode)))
+	if (!vfsuid_eq_kuid(i_uid_into_vfsuid(mnt_userns, inode),
+			    current_fsuid())) {
+		if (vfsgid_in_group_p(i_gid_into_vfsgid(mnt_userns, inode)))
 			allow_utime >>= 3;
 		if (allow_utime & MAY_WRITE)
 			return 1;