From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Micka=EBl_Sala=FCn?= Subject: procfs/d_invalidate break userland Date: Thu, 23 Apr 2015 01:41:02 +0200 Message-ID: <5538318E.6000405@digikod.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="nIbgl2SR42O482SvpU2bfuWja0GBglbuU" Cc: Greg Kroah-Hartman To: Linux-Fsdevel , "Eric W. Biederman" , Al Viro , Miklos Szeredi Return-path: Received: from 14.mo6.mail-out.ovh.net ([46.105.56.113]:59850 "EHLO 14.mo6.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753411AbbDWE1l (ORCPT ); Thu, 23 Apr 2015 00:27:41 -0400 Received: from mail423.ha.ovh.net (gw6.ovh.net [213.251.189.206]) by mo6.mail-out.ovh.net (Postfix) with SMTP id 8A64BFFCA49 for ; Thu, 23 Apr 2015 01:42:24 +0200 (CEST) Sender: linux-fsdevel-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --nIbgl2SR42O482SvpU2bfuWja0GBglbuU Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: quoted-printable Hi, For your information, the commit bbd5192412fdedbae00888316bfe350bf89d0458= (proc: Update proc_flush_task_mnt to use d_invalidate), in the v3.17, br= eak some userland use of procfs. In a user namespace, I'm using /proc//task//fdinfo to mount a t= mpfs, chdir into it, terminate the thread, and use the tmpfs as a p= rivate working directory for PID 1. This trick is useful to disconnect/d_= drop a directory from the current file system and make it inaccessible to= the other processes (kind of an O_TMPFILE for directory). With the v3.17 this is no more possible because it's no more possible to = mount anything in this tmpfs nor use the previously mounted file systems = in this tmpfs. The new d_invalidate is really good to lazily invalidate/umount an entire= hierarchy but I'm not sure the intention was to remove this useful "feat= ure" ;) Micka=EBl --nIbgl2SR42O482SvpU2bfuWja0GBglbuU Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBCgAGBQJVODGWAAoJECLe/t9zvWqVww4H/3cMwJhSdxRtrzfj5rKQyukI sWXBMq7Fat2+HQINpv99KFzSgIRcBEm7TaXiDJSXQ/UtIdZkZH1+iD6EfkyFnSZN C5eYHl8k7UkQo0AXtYOQ0VA9F5o0YVy3rGx2HEbN8VtTvR2jCmhjziLRi8uUzQnW 9daEjG0MthE/QdXry10N2ooQA3KtzqVb/INWPgYWnflLin5VaCoSbvoQy7ZCcidH xTw4O2Qxoi8/nVNKums/C6y5o/Yq8F2D7cLqn+YB0TSmAVxnHXJviyiBMN9453yW WwzMZH2fEP1HN3MfJlhZGv+BstEvwU/glKEs0NzJaO0PKABMhcId8mYVYDwWkDc= =QQoN -----END PGP SIGNATURE----- --nIbgl2SR42O482SvpU2bfuWja0GBglbuU--