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SubjectRe: [PATCH 0/6] detect online disk resize
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>/device/rescan
>
> or
>
> # blockdev --rereadpt <device file>
>
> 2. Other devices (not device mapper)
>
> # blockdev --rereadpt <device file>
>
> 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



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