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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


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 ?


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