ceph: allow idmapped setattr inode op

Enable __ceph_setattr() to handle idmapped mounts. This is just a matter
of passing down the mount's idmapping.

[ aleksandr.mikhalitsyn: adapted to b27c82e12965 ("attr: port attribute
changes to new types") ]

Signed-off-by: Christian Brauner <[e-mail]>
Signed-off-by: Alexander Mikhalitsyn <[e-mail]>
Reviewed-by: Xiubo Li <[e-mail]>
Signed-off-by: Ilya Dryomov <[e-mail]>

fs/ceph/inode.c

···
 #endif /* CONFIG_FS_ENCRYPTION */
 
 	if (ia_valid & ATTR_UID) {
+		kuid_t fsuid = from_vfsuid(idmap, i_user_ns(inode), attr->ia_vfsuid);
+
 		doutc(cl, "%p %llx.%llx uid %d -> %d\n", inode,
 		      ceph_vinop(inode),
 		      from_kuid(&init_user_ns, inode->i_uid),
 		      from_kuid(&init_user_ns, attr->ia_uid));
 		if (issued & CEPH_CAP_AUTH_EXCL) {
-			inode->i_uid = attr->ia_uid;
+			inode->i_uid = fsuid;
 			dirtied |= CEPH_CAP_AUTH_EXCL;
 		} else if ((issued & CEPH_CAP_AUTH_SHARED) == 0 ||
-			   !uid_eq(attr->ia_uid, inode->i_uid)) {
+			   !uid_eq(fsuid, inode->i_uid)) {
 			req->r_args.setattr.uid = cpu_to_le32(
-				from_kuid(&init_user_ns, attr->ia_uid));
+				from_kuid(&init_user_ns, fsuid));
 			mask |= CEPH_SETATTR_UID;
 			release |= CEPH_CAP_AUTH_SHARED;
 		}
 	}
 	if (ia_valid & ATTR_GID) {
+		kgid_t fsgid = from_vfsgid(idmap, i_user_ns(inode), attr->ia_vfsgid);
+
 		doutc(cl, "%p %llx.%llx gid %d -> %d\n", inode,
 		      ceph_vinop(inode),
 		      from_kgid(&init_user_ns, inode->i_gid),
 		      from_kgid(&init_user_ns, attr->ia_gid));
 		if (issued & CEPH_CAP_AUTH_EXCL) {
-			inode->i_gid = attr->ia_gid;
+			inode->i_gid = fsgid;
 			dirtied |= CEPH_CAP_AUTH_EXCL;
 		} else if ((issued & CEPH_CAP_AUTH_SHARED) == 0 ||
-			   !gid_eq(attr->ia_gid, inode->i_gid)) {
+			   !gid_eq(fsgid, inode->i_gid)) {
 			req->r_args.setattr.gid = cpu_to_le32(
-				from_kgid(&init_user_ns, attr->ia_gid));
+				from_kgid(&init_user_ns, fsgid));
 			mask |= CEPH_SETATTR_GID;
 			release |= CEPH_CAP_AUTH_SHARED;
 		}
···
 	if (err)
 		return err;
 
-	err = setattr_prepare(&nop_mnt_idmap, dentry, attr);
+	err = setattr_prepare(idmap, dentry, attr);
 	if (err != 0)
 		return err;
 
···
 	err = __ceph_setattr(idmap, inode, attr, NULL);
 
 	if (err >= 0 && (attr->ia_valid & ATTR_MODE))
-		err = posix_acl_chmod(&nop_mnt_idmap, dentry, attr->ia_mode);
+		err = posix_acl_chmod(idmap, dentry, attr->ia_mode);
 
 	return err;
 }