From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bernd Schubert Subject: Re: [PATCH 0/4] 32/64 bit llseek hashes v2 Date: Mon, 08 Aug 2011 17:47:21 +0200 Message-ID: <4E400509.8090804@itwm.fraunhofer.de> References: <20110808153432.1872437.85783.stgit@fsdevel3> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, yong.fan-KloliPT79xf2eFz/2MeuCQ@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tytso-3s7WtUTddSA@public.gmane.org, adilger-KloliPT79xf2eFz/2MeuCQ@public.gmane.org To: linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: In-Reply-To: <20110808153432.1872437.85783.stgit@fsdevel3> Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org Oh sorry, I forgot to set the correct subject line in my stg command line :( On 08/08/2011 05:37 PM, Bernd Schubert wrote: > With the ext3/ext4 directory index implementation hashes are used to specify > offsets for llseek(). For compatibility with NFSv2 and 32-bit user space > on 64-bit systems (kernel space) ext3/ext4 currently only return 32-bit > hashes and therefore the probability of hash collisions for larger directories > is rather high. As recently reported on the NFS mailing list that theoretical > problem also happens on real systems: > http://comments.gmane.org/gmane.linux.nfs/40863 > > The following series adds two new f_mode flags to tell ext4 > to use 32-bit or 64-bit hash values for llseek() calls. > These flags can then used by network file systems, such as NFS, to > request 32-bit or 64-bit offsets (hashes). > > Version 2: > - use f_mode instead of O_* flags and also in a separate patch > - introduce EXT4_HTREE_EOF_32BIT and EXT4_HTREE_EOF_64BIT > - fix SEEK_END in ext4_dir_llseek() > - set f_mode flags in NFS code as early as possible and introduce a new > NFSD_MAY_64BIT_COOKIE flag for that > > -- > Bernd Schubert > Fraunhofer ITWM > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailgw1.uni-kl.de ([131.246.120.220]:53830 "EHLO mailgw1.uni-kl.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751907Ab1HHPrX (ORCPT ); Mon, 8 Aug 2011 11:47:23 -0400 Message-ID: <4E400509.8090804@itwm.fraunhofer.de> Date: Mon, 08 Aug 2011 17:47:21 +0200 From: Bernd Schubert To: linux-nfs@vger.kernel.org, linux-ext4@vger.kernel.org CC: hch@infradead.org, yong.fan@whamcloud.com, linux-fsdevel@vger.kernel.org, tytso@mit.edu, adilger@whamcloud.com Subject: Re: [PATCH 0/4] 32/64 bit llseek hashes v2 References: <20110808153432.1872437.85783.stgit@fsdevel3> In-Reply-To: <20110808153432.1872437.85783.stgit@fsdevel3> Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Oh sorry, I forgot to set the correct subject line in my stg command line :( On 08/08/2011 05:37 PM, Bernd Schubert wrote: > With the ext3/ext4 directory index implementation hashes are used to specify > offsets for llseek(). For compatibility with NFSv2 and 32-bit user space > on 64-bit systems (kernel space) ext3/ext4 currently only return 32-bit > hashes and therefore the probability of hash collisions for larger directories > is rather high. As recently reported on the NFS mailing list that theoretical > problem also happens on real systems: > http://comments.gmane.org/gmane.linux.nfs/40863 > > The following series adds two new f_mode flags to tell ext4 > to use 32-bit or 64-bit hash values for llseek() calls. > These flags can then used by network file systems, such as NFS, to > request 32-bit or 64-bit offsets (hashes). > > Version 2: > - use f_mode instead of O_* flags and also in a separate patch > - introduce EXT4_HTREE_EOF_32BIT and EXT4_HTREE_EOF_64BIT > - fix SEEK_END in ext4_dir_llseek() > - set f_mode flags in NFS code as early as possible and introduce a new > NFSD_MAY_64BIT_COOKIE flag for that > > -- > Bernd Schubert > Fraunhofer ITWM > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html