From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Nieder Subject: Re: [PATCH] vfs: introduce FS_IOC_SYNCFS to sync a single super Date: Sat, 27 Nov 2010 23:04:07 -0600 Message-ID: <20101128050407.GA16903@burratino> References: <20100826170142.e029cff5.akpm@linux-foundation.org> <20101127223217.GA26820@burratino> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20101127223217.GA26820@burratino> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andrew Morton Cc: Sage Weil , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Arnd Bergmann List-Id: linux-api@vger.kernel.org Jonathan Nieder wrote: > Since > ancient times, that has been done with the "rename trick": [...] > Great. Problem is, filesystems with delayed allocation like XFS, > ubifs, ext4, hfs+ don't cope so well with that[1]. [...] > [1] Yes, even after v2.6.30-rc1~416^2~15 (ext4: Automatically allocate > delay allocated blocks on rename, 2009-02-23). > See https://bugzilla.kernel.org/show_bug.cgi?id=18632 Sorry, wrong link. The example meant was https://bugzilla.kernel.org/show_bug.cgi?id=15910 "zero-length files and performance degradation", reported against 2.6.32: | To reproduce it: | * install a fresh Ubuntu Lucid system on an ext4 filesystem, or Debian with | dpkg < 1.15.6 or Ubuntu Karmic | * install a package, wait a few seconds and simulate a crash | $ sudo apt-get install some-package; sleep 5; sudo echo b > /proc/sysrq-trigger | * reboot | $ ls -l /var/lib/dpkg/info/some-package.* will list empty maintainer's scripts. | $ ls -l /var/cache/apt/archive/some-package.* will show the empty archive | you've just downloaded | At this stage, the package manager is unusable and the common user cannot | update anything anymore. | | This behavior is observed with data=ordered and with or without the mount | option auto_da_alloc. Sorry for the confusion. Jonathan