From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Thu, 23 Aug 2007 20:59:46 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with SMTP id l7O3xb4p025116 for ; Thu, 23 Aug 2007 20:59:41 -0700 Message-ID: <46CE581A.2000405@sgi.com> Date: Fri, 24 Aug 2007 14:01:30 +1000 From: Vlad Apostolov MIME-Version: 1.0 Subject: TAKE 969192: Default mount option "noikeep" makes the inode generation number non-persistent Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: sgi.bugs.xfs@engr.sgi.com Cc: linux-xfs@oss.sgi.com XFS inodes are dynamically allocated on demand, rather than being allocated at mkfs time. Chunks of 64 inodes are allocated at once, but they are never freed. Over time, this can lead to filesystem fragmentation, clusters of inodes and the btrees which point at them can be scattered around the system. By freeing clusters as they are emptied, we reduce fragmentation of the free space after removing files. This in turn allows us to make better placement decisions when repopulating a filesystem. The XFSMNT_IDELETE mount option enables freeing clusters when they get empty. Unfortunately a side effect of freeing inode clusters is that the inode generation numbers of such inodes would be reset to zero when the cluster is reclaimed. This is a problem in particular for a DMAPI enabled filesystem as the the DMAPI handles need to be unique and persistent in time. An unique DMAPI handle is built with the help of the inode generation number. When the last one is prematurely reset by an inode cluster reclaim, there is a high probability of different generation inodes to end up having identical DMAPI handles. To avoid the problem with identical DMAPI handles, the XFSMNT_IDELETE mount option should be set as default, only if the filesystem is not mounted with XFSMNT_DMAPI. Date: Fri Aug 24 13:54:57 AEST 2007 Workarea: soarer.melbourne.sgi.com:/home/vapo/isms/linux-xfs Inspected by: dgc, markgw Author: vapo The following file(s) were checked into: longdrop.melbourne.sgi.com:/isms/linux/2.6.x-xfs-melb Modid: xfs-linux-melb:xfs-kern:29486a fs/xfs/xfs_vfsops.c - 1.527 - changed http://oss.sgi.com/cgi-bin/cvsweb.cgi/xfs-linux/xfs_vfsops.c.diff?r1=text&tr1=1.527&r2=text&tr2=1.526&f=h - pv 969192, rv dgc, markgw - Imply "ikeep" default mount option for DMAPI enabled filestems.