[Bug 1469143] Re: kpartx -d fails with image paths longer than 63 characters

[Risto Kankkunen]

In addition to not handling long paths, kpartx also fails to handle
relative paths correctly. Here's an example:

for d in 1 2
do
  mkdir $d && (
    cd $d &&
    dd if=/dev/zero of=disk.img seek=8k count=1 2> /dev/null &&
    (echo n;echo;echo;echo;echo;echo w) | fdisk disk.img >/dev/null &&
    kpartx -av disk.img
  )
done

Expected result:
add map loop1p1 (254:0): 0 6145 linear /dev/loop0 2048
add map loop2p1 (254:1): 0 6145 linear /dev/loop1 2048

Actual result:
add map loop1p1 (254:0): 0 6145 linear /dev/loop0 2048
add map loop1p1 (254:0): 0 6145 linear /dev/loop0 2048

Currently kpartx end up modifying the existing binding instead of
creating a new one.

Both the long path problem and the relative path problem are caused by
kpartx trying to use the binding name to store the image file path and
assuming that the name would uniquely identify a binding.

The correct way is to use the device and inode numbers of the image
files to identify which loop mount is attached to which image file. I
have attached a patch which does exactly this.


** Patch added: "Use inode to match loopback mount to backing file"
   https://bugs.launchpad.net/ubuntu/+source/multipath-tools/+bug/1469143/+attachment/4422343/+files/0014-kpartx-long-path.patch

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https://bugs.launchpad.net/bugs/1469143

Title:
  kpartx -d fails with image paths longer than 63 characters

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