Bug#714581: Debian Installer "partition disks" step fails on s390/s390x when a "small" disk is used

[Stephen Powell <zlinuxman@wowway.com>]

Package: debian-installer
Version: 20130613
Severity: important
X-Debbugs-CC: debian-s390@lists.debian.org

I recently discovered a bug in the Debian installer on the s390/s390x
architecture.  The bug occurs when a "small" disk is used.  As an
illustration, I had four DASDs in my installation environment, all of
them device type 3390, each with a single partition occupying the
entire disk, as follows:

Device   size in     file     mount
Number   cylinders   system   point 

63FC     3338        ext3     /
63FD       75        ext2     /boot
63FE      500        ext3     /home
63FF     1457        swap     swap

mke2fs for the 63FD device (/dev/dasdb1 in this case) fails because
the block size assumed by default was 1024.  This is normally
fine for i386 and amd64 architectures, since the physical disk block
size is normally 512.  The file system block size must be an
integral multiple of the physical disk block size.  And 1024 is a
multiple of 512.  But on the s390/s390x platform, dasdfmt defaults
to a block size of 4096, regardless of the size of the disk.  Thus,
in the s390/s390x environment, the only acceptable block size (-b
option) for mke2fs is 4096.  Thus, mke2fs fails, which causes the
subsequent mount command to fail, which causes the "partition disks"
step of the installer to fail, which causes the entire installation
to fail.

The definition of a "small" disk is one which results in a default
block size chosen by mke2fs which is lower than 4096.  I'm not sure
where that boundary is.

-- 
  .''`.     Stephen Powell    
 : :'  :
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