On Thu, Sep 04, 2008 at 02:27:15PM -0600, 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. > Hello and thanks for the patch! How about device mapper.. what's needed to make it detect/support online resizes? I'm specificly interested in online resizing (growing) dm-multipath devices.. Basicly I'd like to have LVM PV on dm-multipath device.. so first I need to get the actual disks resized, then dm-multipath device, and finally run pvresize. I know dm-multipath part can be done atm using this (hacky) method: https://www.redhat.com/archives/dm-devel/2008-August/msg00033.html -- Pasi -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
