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Re: [dm-devel] Adding/removing multi-pathed disk partitions



goggin, edward wrote:

Should one be using the multi-path device-mapper mapped device
name or one of the SCSI target device names for the whole disk
device when modifying a SCSI disk's partition table with fdisk(8)?

If the former, drivers/block/ioctl.c:blkdev_reread_part()
currently returns EINVAL since the mapped device is not
partitionable.  I can't imagine the recommendation is the
latter, since there is no mechanism in place to synchronize
the kernel's partition table handling amongst multiple target
devices.

--

As discussed earlier, one face of this problem is that kpartx does buffered reads to grab the on-disk partition table, leading to situations where kpartx ->fdisk -> kpartx sequence does not garanty partitons-to-maps layout will reflect reality.

To address this particular problem, do you think adding O_DIRECT to the open() call in kpartx.c would be enough ?

Regards,
cvaroqui


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