[parted-devel] [PATCH] libparted/dasd: improve lvm/raid flag handling for DASD-CDL

[Wang Dong]

On 04/21/2017 08:47 PM, Phil Susi wrote:
> On 4/20/2017 10:07 PM, Wang Dong wrote:
>> But the flag cannot be read with the presence of the filesystem previously.
>> That's why the change.
> How so?  The flag is in the partition table.  What data is written to
> the partition has nothing to do with the flag.  Whether you have a
> filesystem or not, the flag is still there in the partition table.
>
        ▷       ▷       if ((strncmp(PART_TYPE_RAID, str, 6) == 0) &&¶
  451▷       ▷           (ped_file_system_probe(&part->geom) == NULL))¶
  452▷       ▷       ▷       ped_partition_set_flag(part, 
PED_PARTITION_RAID, 1);¶
  453▷       ▷ else¶
  454▷       ▷       ▷       ped_partition_set_flag(part, 
PED_PARTITION_RAID, 0);¶
  455¶
  456▷       ▷       if ((strncmp(PART_TYPE_LVM, str, 6) == 0) &&¶
  457▷       ▷           (ped_file_system_probe(&part->geom) == NULL))¶
  458▷       ▷       ▷       ped_partition_set_flag(part, 
PED_PARTITION_LVM, 1);¶
  459▷       ▷ else¶
  460▷       ▷       ▷       ped_partition_set_flag(part, 
PED_PARTITION_LVM, 0);¶

Maybe I did not put it clearly. The flag is on the partition table. But 
it cannot be read with a filesystem existence.


The code above is from libparted/labels/dasd.c, function dasd_read(), 
master branch.

As I also tested it, with a filesystem, when I set the flag in 
interactive mode, I can read the flag with "print".
But I can not get it after I re-read the device. And I can verify the 
flag's existence with other tool.
If I set the flag in script mode,  I cannot read the flag either. That 
means user cannot see the flag, although it exists.

If I missed something, please let me know. Thanks in advance.

>> Nothing goofy. Just the property of the lvm/raid. Because when to
>> make a partition to lvm/raid, the filesystem will be ripped out.
> Not by parted it won't.  We just update the partition table, and it is
> up to the user to mess with the filesystem.  If they don't run pvcreate
> on the partition after setting the lvm flag, then the filesystem is
> still there and works just fine.  These flags simply don't matter in
> practice, and so I never bother setting them even though I do use raid
> and lvm.
>

-- 
Best regards. Wang Dong