From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 0/6] detect online disk resize Date: Fri, 5 Sep 2008 09:02:47 +0200 Message-ID: <20080905070247.GN20055@kernel.dk> References: <20080904202714.10456.88061.stgit@bob.kio> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from pasmtpb.tele.dk ([80.160.77.98]:39760 "EHLO pasmtpB.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751436AbYIEHCw (ORCPT ); Fri, 5 Sep 2008 03:02:52 -0400 Content-Disposition: inline In-Reply-To: <20080904202714.10456.88061.stgit@bob.kio> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Andrew Patterson Cc: linux-scsi@vger.kernel.org, James.Bottomley@HansenPartnership.com, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, andmike@linux.vnet.ibm.com, mike.miller@hp.com, genanr@emsphone.com, jmoyer@redhat.com On Thu, Sep 04 2008, Andrew Patterson wrote: > Resubmitting this patch against Jens's linux-2.6-block:for-2.6.28 repo. > > This patch series handles online disk resizes that are currently not > completely recognized by the kernel using the existing revalidate_disk > routines. An online resize can occur when growing or shrinking a > Fibre Channel LUN or perhaps by adding a disk to an existing RAID > volume. > > The kernel currently recognizes a device size change when the > lower-level revalidate_disk routines are called; however, the block > layer does not use the new size while it has any current openers on > the device. So, for example, if LVM has an volume open on the device, > you will generally not see the size change until after a reboot. We > fix this problem by creating a wrapper to be used with lower-level > revalidate_disk routines. This wrapper first calls the lower-level > driver's revalidate_disk routine. It then compares the gendisk > capacity to the block devices inode size. If there is a difference, we > adjust the block device's size. If the size has changed, we then flush > the disk for safety. The size is also checked in rescan_partitions > which is called when the device is opened or when the BLKRRPART ioctl > is called. > > There are several ways to "kick off" a device size change: > > 1. For SCSI devices do: > > # echo 1 > /sys/class/scsi_device//device/rescan > > or > > # blockdev --rereadpt > > 2. Other devices (not device mapper) > > # blockdev --rereadpt > > I have tested this patch on SCSI and SmartArray (cciss) > devices. Device mapper still does not recognize device size changes > until the device is restarted. > > > Diff stats: > > drivers/scsi/sd.c | 4 +- > fs/block_dev.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++--- > fs/partitions/check.c | 3 +- > include/linux/fs.h | 3 ++ > 4 files changed, 93 insertions(+), 8 deletions(-) > > Commits: > > - Wrapper for lower-level revalidate_disk routines. > - Adjust block device size after an online resize of a disk. > - Check for device resize in rescan_partitions. > - SCSI sd driver calls revalidate_disk wrapper. > - Added flush_disk to factor out common buffer cache flushing code. > - Call flush_disk() after detecting an online resize. Thanks Andrew, applied. -- Jens Axboe