From owner-freebsd-fs@FreeBSD.ORG Tue Apr 5 14:16:36 2011 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E0E6A1065679 for ; Tue, 5 Apr 2011 14:16:35 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id 64FF08FC08 for ; Tue, 5 Apr 2011 14:16:34 +0000 (UTC) Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id p35EGV6E062465 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 5 Apr 2011 17:16:31 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4) with ESMTP id p35EGVja032212 for ; Tue, 5 Apr 2011 17:16:31 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4/Submit) id p35EGVp9032211 for freebsd-fs@freebsd.org; Tue, 5 Apr 2011 17:16:31 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Tue, 5 Apr 2011 17:16:31 +0300 From: Kostik Belousov To: freebsd-fs@freebsd.org Message-ID: <20110405141631.GA78089@deviant.kiev.zoral.com.ua> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="FYjy/y/1gvMuB097" Content-Disposition: inline User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-3.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00, DNS_FROM_OPENWHOIS autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua Subject: Knob to turn off _POSIX_NO_TRUNC X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 05 Apr 2011 14:16:36 -0000 --FYjy/y/1gvMuB097 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable =46rom very old and gloomy SysV times I remembered filesystem behaviour that silently truncated the file name components to the NAME_MAX limit, that was, AFAIR, 14. To much of my dismay, I met some usermode software recently that blindly tried to create the file from externally provided name, and sometimes failed with ENAMETOOLONG in similar situation. The authors are not cooperative. I ended up with the following hack, which almost turns off the _POSIX_NO_TRUNC behaviour, globally on the system. Patch allowed me to proceed. The cost in the default case is a single check, which is performed only on ENAMETOOLONG path. I am too chicken to commit it without prior discussion. diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c index 50a2570..e9e7697 100644 --- a/sys/kern/vfs_lookup.c +++ b/sys/kern/vfs_lookup.c @@ -99,6 +99,11 @@ SYSCTL_INT(_vfs, OID_AUTO, lookup_shared, CTLFLAG_RW, &l= ookup_shared, 0, "Enables/Disables shared locks for path name translation"); TUNABLE_INT("vfs.lookup_shared", &lookup_shared); =20 +static int lookup_trim; +SYSCTL_INT(_vfs, OID_AUTO, lookup_trim, CTLFLAG_RW, &lookup_trim, 0, + "Enables/Disables trim of the long path component instead of ENAMETOOL= ONG"); +TUNABLE_INT("vfs.lookup_trim", &lookup_trim); + /* * Convert a pathname into a pointer to a locked vnode. * @@ -514,8 +519,14 @@ dirloop: continue; cnp->cn_namelen =3D cp - cnp->cn_nameptr; if (cnp->cn_namelen > NAME_MAX) { - error =3D ENAMETOOLONG; - goto bad; + if (!lookup_trim) { + error =3D ENAMETOOLONG; + goto bad; + } + ndp->ni_pathlen -=3D cnp->cn_namelen - NAME_MAX; + cnp->cn_namelen =3D NAME_MAX; + strcpy(cnp->cn_nameptr + cnp->cn_namelen, cp); + cp =3D cnp->cn_nameptr + cnp->cn_namelen; } #ifdef NAMEI_DIAGNOSTIC { char c =3D *cp; --FYjy/y/1gvMuB097 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk2bJD4ACgkQC3+MBN1Mb4j8JgCdHDI6bfeegkO1rSFiIf8RblPC YnoAoNl3bJkPaEcn07P6xUaurYrxo3PW =Ntd5 -----END PGP SIGNATURE----- --FYjy/y/1gvMuB097--