This patch now uses dd entirely to wipe the disk, make it
much easier to wipe in blocks so we can give interactive feedback
about the status.
---
 lib/backend.py   |   28 ++++++++++++++++++++++------
 lib/constants.py |    2 +-
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/lib/backend.py b/lib/backend.py
index 8abe5a6..1edccae 100644
--- a/lib/backend.py
+++ b/lib/backend.py
@@ -1287,32 +1287,48 @@ def BlockdevCreate(disk, size, owner, on_primary, info):
   return device.unique_id
 
 
-def _WipeDevice(path):
+def _WipeDevice(path, offset, size):
   """This function actually wipes the device.
 
   @param path: The path to the device to wipe
+  @param offset: The offset in MiB in the file
+  @param size: The size in MiB to write
 
   """
-  result = utils.RunCmd("%s%s" % (constants.WIPE_CMD, utils.ShellQuote(path)))
+  cmd = ["dd", "if=/dev/zero", "seek=%d" % offset,
+         "bs=%d" % constants.WIPE_BLOCK_SIZE, "oflag=direct", "of=%s" % path,
+         "count=%d" % size]
+  result = utils.RunCmd(cmd)
 
   if result.failed:
     _Fail("Wipe command '%s' exited with error: %s; output: %s", result.cmd,
           result.fail_reason, result.output)
 
 
-def BlockdevWipe(disk):
+def BlockdevWipe(disk, offset, size):
   """Wipes a block device.
 
   @type disk: L{objects.Disk}
   @param disk: the disk object we want to wipe
+  @type offset: int
+  @param offset: The offset in MiB in the file
+  @type size: int
+  @param size: The size in MiB to write
 
   """
   try:
     rdev = _RecursiveFindBD(disk)
-  except errors.BlockDeviceError, err:
-    _Fail("Cannot execute wipe for device %s: device not found", err)
+  except errors.BlockDeviceError:
+    rdev = None
+
+  if not rdev:
+    _Fail("Cannot execute wipe for device %s: device not found", disk.iv_name)
+
+  # Do cross verify some of the parameters
+  assert(offset <= rdev.size)
+  assert(offset + size <= rdev.size)
 
-  _WipeDevice(rdev.dev_path)
+  _WipeDevice(rdev.dev_path, offset, size)
 
 
 def BlockdevRemove(disk):
diff --git a/lib/constants.py b/lib/constants.py
index b66b6eb..8529295 100644
--- a/lib/constants.py
+++ b/lib/constants.py
@@ -96,7 +96,7 @@ CONFD_GROUP = _autoconf.CONFD_GROUP
 NODED_USER = _autoconf.NODED_USER
 
 # Wipe
-WIPE_CMD = _autoconf.WIPE_CMD
+WIPE_BLOCK_SIZE = 1024**2
 
 # file paths
 DATA_DIR = _autoconf.LOCALSTATEDIR + "/lib/ganeti"
-- 
1.7.1

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