[parted-devel] [PATCH] libparted: Fixed bug in initializing and re-reading partition table of FBA devices

[Phillip Susi]

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On 10/28/2013 5:50 AM, Nageswara R Sastry wrote:
> Yes, this kind of disk can not be partitioned and having one
> partition for the whole disk. Parted tool's DASD code correctly
> identifies this kind of disk and the partition. This helps in
> successful installation of an Operating System on the top of FBA
> disk(s).

Ok, so if the disk can't be partitioned, then why run parted on it at
all?  And why should the kernel bother creating this dummy partition?
 Just put your filesystem on /dev/dasda; there's no need for a
/dev/dasda1.

> FBA disk does not contain a partition table to be thrown/created
> by the BLKPG ioctl. With out BLKRRPART ioctl code, kernel is not
> aware of the implicit/single partition available with FBA disk.

Why not?  The kernel should have created it automatically when the
disk was first plugged in.  Since you can't actually create partitions
on the disk, then what is parted doing to it?

It occurs to me that the answers to my questions could be that you
still need to use parted to create the dasd disk label and the
implicit partition does not include the disk label area, kind of like
the loop label.  Is this the case?  If so, then I think your patch is
going about it the wrong way.  Instead of modifying arch/linux.c to be
hard coded to call BLKRRPRT, you should fix labels/dasd.c to create
this implicit partition which parted print would then properly show,
and linux.c should correctly inform the kernel of it with BLKPG.

In other words, parted print should correctly show this implicit
partition instead of showing no partitions, and having the implicit
partition shoved in by the kernel.

> From my colleagues learned that, time delay for all the iterations
> together should not cross '2 seconds'. Is that acceptable? or do
> you have a different number.

Sure, that sounds good.  This sort of thing usually does something
like sleep for 0.1 seconds between attempts with a maximum of 20
attempts to give 2 seconds.


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