[blivet] Add support for FBA EDEV/EAV installation. (#885957)

David Lehman dlehman at redhat.com
Wed Jun 5 16:22:19 UTC 2013


On Wed, 2013-06-05 at 08:56 -0400, Samantha N. Bueno wrote:
> Note: these patches have been tested by IBM. Two minor issues arose
> from testing (noted in comment 15 of the bug if interested), but they
> are non-fatal and not directly related to the patches below.
> 
> ====
> 
> Fixed Block Access (FBA) DASDs are mainframe-specific disk devices
> which are layed out as a sequence of 512-byte sectors. In contrast
> to ECKD DASDs, these disks do not require formatting and resemble
> the LBA layout of non-mainframe disks. Despite this resemblance,
> the Linux kernel applies special handling during partition detection
> for FBA DASDs, resulting in a single, immutable partition being
> reported.
> 
> While actual FBA DASD hardware is no longer available, the z/VM
> hypervisor can simulate FBA DASD disks, backed by either ECKD or
> SCSI devices.

This should really not require _any_ special code in blivet unless to
add support for a new disklabel type. I have several comments, below.

> 
> This patch adds support for successful installation on FBA DASD
> devies (EDEV)
> 
> Patches originally submitted by Nageswara R Sastry
> <rnsastry at linux.vnet.ibm.com>; I only refactored them as needed to mesh
> with current code since they were written last year.
> ---
>  blivet/__init__.py          |  7 +++++--
>  blivet/devices.py           | 17 +++++++++--------
>  blivet/formats/disklabel.py | 23 ++++++++++++++++++++++-
>  blivet/partitioning.py      |  2 ++
>  4 files changed, 38 insertions(+), 11 deletions(-)
> 
> diff --git a/blivet/__init__.py b/blivet/__init__.py
> index 2d69eb1..95d77e0 100644
> --- a/blivet/__init__.py
> +++ b/blivet/__init__.py
> @@ -802,8 +802,11 @@ class Blivet(object):
>                          # disk. Still, we need it out of the devicetree.
>                          self.devicetree._removeDevice(part, moddisk=False)
>  
> -        if disk.partitioned and disk.format.partitions:
> -            raise ValueError("cannot initialize a disk that has partitions")
> +        log.debug("Checking to see if device is LDL DASD")
> +        if not disk.format.isLDL():
> +            log.debug("Disk is not LDL DASD")
> +            if disk.partitioned and disk.format.partitions:
> +                raise ValueError("cannot initialize a disk that has partitions")

I don't want the logs littered with strings about LDL DASD when 99.8% of
the user-base doesn't know or care what that is. If there must be
anything in the logs about these it should be only when we see one.

>  
>          # remove existing formatting from the disk
>          destroy_action = ActionDestroyFormat(disk)
> diff --git a/blivet/devices.py b/blivet/devices.py
> index 2bb7289..e8b3e0b 100644
> --- a/blivet/devices.py
> +++ b/blivet/devices.py
> @@ -1484,15 +1484,16 @@ class PartitionDevice(StorageDevice):
>      def _create(self):
>          """ Create the device. """
>          log_method_call(self, self.name, status=self.status)
> -        self.disk.format.addPartition(self.partedPartition)
> +        # Do not create partition on LDL formatted
> +        if not self.disk.format.isLDL():
> +            self.disk.format.addPartition(self.partedPartition)

So, what -- we're just going to silently not add a partition we have
already planned to add? This isn't right.

>  
> -        self._wipe()
> -        try:
> -            self.disk.format.commit()
> -        except DiskLabelCommitError:
> -            part = self.disk.format.partedDisk.getPartitionByPath(self.path)
> -            self.disk.format.removePartition(part)
> -            raise
> +            try:
> +                self.disk.format.commit()
> +            except DiskLabelCommitError:
> +                part = self.disk.format.partedDisk.getPartitionByPath(self.path)
> +                self.disk.format.removePartition(part)
> +                raise
>  
>      def _postCreate(self):
>          if self.isExtended:
> diff --git a/blivet/formats/disklabel.py b/blivet/formats/disklabel.py
> index 90b73f3..7cb41f5 100644
> --- a/blivet/formats/disklabel.py
> +++ b/blivet/formats/disklabel.py
> @@ -144,6 +144,19 @@ class DiskLabel(DeviceFormat):
>          log_method_call(self, device=self.device, labelType=self._labelType)
>          return parted.freshDisk(device=self.partedDevice, ty=self._labelType)
>  
> +    def newPartedDisk(self):
> +        """ Return a new, empty parted.Disk instance for this device. """
> +        log_method_call(self, device=self.device)
> +        return parted.newDisk(device=self.partedDevice)
> +
> +    def isLDL(self):
> +        """ Return True for LDL formatted disk. """
> +        log_method_call(self, device=self.device)
> +        if (self._labelType == "dasd" and self.partedDisk.maxPrimaryPartitionCount == 1):
> +            return True
> +        else:
> +            return False
> +
>      @property
>      def partedDisk(self):
>          if not self._partedDisk:
> @@ -165,7 +178,13 @@ class DiskLabel(DeviceFormat):
>                  # preexisting disklabels if the passed type was wrong
>                  self._labelType = self._partedDisk.type
>              else:
> -                self._partedDisk = self.freshPartedDisk()
> +                if (self._labelType == "dasd"):
> +                    self._partedDisk = self.newPartedDisk()
> +                    # Don't want to break for the normal DASD
> +                    if self._partedDisk.maxPrimaryPartitionCount != 1:
> +                        self._partedDisk = self.freshPartedDisk()
> +                else:
> +                    self.partedDisk = self.freshPartedDisk()

Why does this special type of DASD require the use of newDisk instead of
freshDisk, which works for every other disk type?

>  
>              # turn off cylinder alignment
>              if self._partedDisk.isFlagAvailable(parted.DISK_CYLINDER_ALIGNMENT):
> @@ -442,6 +461,8 @@ class DiskLabel(DeviceFormat):
>              return 1
>          elif self.labelType == "sun":
>              return 3
> +        elif self.isLDL():
> +            return 1
>          else:
>              return 0
>  
> diff --git a/blivet/partitioning.py b/blivet/partitioning.py
> index 8660969..1bd0d08 100644
> --- a/blivet/partitioning.py
> +++ b/blivet/partitioning.py
> @@ -425,6 +425,8 @@ def getNextPartitionType(disk, no_primary=None):
>                  part_type = parted.PARTITION_LOGICAL
>      elif extended and logical_count < max_logicals:
>          part_type = parted.PARTITION_LOGICAL
> +    elif (disk.type == "dasd" and disk.maxPrimaryPartitionCount == 1):
> +        part_type = parted.PARTITION_NORMAL

Is this really necessary? If these disks have special requirements
and/or limitations they should have code in parted (if not a new
disklabel type) to convey these instead of junking up blivet with all
this special-case code.

>  
>      return part_type
>  




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