[LVM2 PATCH] Fix lvcreate's checking of the number of PVs

[LVM2 PATCH] Fix lvcreate's checking of the number of PVs

[Jun'ichi Nomura]

Hi,

While not explained in man page, lvcreate can take tags of PVs
as a specification of allocatable PVs.
e.g. if you have 2 MD RAID1 disks and other disks in your vg,
      you can do:
       pvchange --addtag raid1 /dev/md[01]
       lvcreate -L100M -i2 vg @raid1
      instead of 'lvcreate -L100M -i2 vg /dev/md0 /dev/md1'

However, lvcreate checks the number of PVs based on the number of
arguments, so it fails even if the number of PVs for the tag is many
enough.

The same check is done later in the allocation code.
So it's safe to remove the checks here.

A patch to fix this and a reproducer script is attached.

Thanks,
-- 
Jun'ichi Nomura, NEC Corporation of America
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[LVM2 PATCH] Fix lvcreate's checking of the number of PVs

[Jun'ichi Nomura]

Jun'ichi Nomura wrote:
> While not explained in man page, lvcreate can take tags of PVs
> as a specification of allocatable PVs.
> e.g. if you have 2 MD RAID1 disks and other disks in your vg,
>       you can do:
>        pvchange --addtag raid1 /dev/md[01]
>        lvcreate -L100M -i2 vg @raid1
>       instead of 'lvcreate -L100M -i2 vg /dev/md0 /dev/md1'
> 
> However, lvcreate checks the number of PVs based on the number of
> arguments, so it fails even if the number of PVs for the tag is many
> enough.
> 
> The same check is done later in the allocation code.
> So it's safe to remove the checks here.
> 
> A patch to fix this and a reproducer script is attached.

After the fix, 'argc' is no longer used and should be removed
in both _read_stripe_params() and _read_mirror_params().

This is the updated version of the patch.

Thanks,
-- 
Jun'ichi Nomura, NEC Corporation of America
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