def ReleaseBdevPartitionMapping(loop_dev_path):
"""Release allocated dm devices and loopback devices.
@type loop_dev_path: string
@param loop_dev_path: path of loopback device returned by
L{CreateBdevPartitionMapping}
"""
result = utils_process.RunCmd(["kpartx", "-d", loop_dev_path])
if result.failed:
raise errors.CommandError(
"Failed to release partition mapping of %s: %s" %
(loop_dev_path, result.output))
# The invocation of udevadm settle was added here because users had issues
# with the loopback device still being busy after kpartx / earlier commands
# did their work.
result = utils_process.RunCmd(["udevadm", "settle"])
if result.failed:
raise errors.CommandError("Waiting on udev failed: %s" % result.output)
result = utils_process.RunCmd(["losetup", "-d", loop_dev_path])
if result.failed:
raise errors.CommandError("Failed to detach %s: %s" %
(loop_dev_path, result.output))
def CreateBdevPartitionMapping(image_path):
"""Create dm device for each partition of disk image.
This operation will allocate a loopback and a device-mapper device to map
partitions.
You must call L{ReleaseBdevPartitionMapping} to clean up resources allocated
by this function call.
@type image_path: string
@param image_path: path of multi-partition disk image
@rtype: tuple(string, list(string)) or NoneType
@return: returns the tuple(loopback_device, list(device_mapper_files)) if
image_path is a multi-partition disk image. otherwise, returns None.
"""
# Unfortunately, there are two different losetup commands in this world.
# One has the '-s' switch and the other has the '--show' switch to provide the
# same functionality.
result = utils_process.RunCmd(["losetup", "-f", "-s", image_path])
if result.failed and "invalid option -- 's'" in result.stderr:
result = utils_process.RunCmd(["losetup", "-f", "--show", image_path])
if result.failed:
raise errors.CommandError("Failed to setup loop device for %s: %s" %
(image_path, result.output))
loop_dev_path = result.stdout.strip()
logging.debug("Loop dev %s allocated for %s", loop_dev_path, image_path)
result = utils_process.RunCmd(["kpartx", "-a", "-v", loop_dev_path])
if result.failed:
# Just try to cleanup allocated loop device
utils_process.RunCmd(["losetup", "-d", loop_dev_path])
raise errors.CommandError(
"Failed to add partition mapping for %s: %s" %
(image_path, result.output))
dm_devs = [x.split(" ") for x in result.stdout.split("\n") if x]
if dm_devs:
dm_dev_paths = [
utils_io.PathJoin("/dev/mapper", x[2]) for x in dm_devs
]
return (loop_dev_path, dm_dev_paths)
else:
# image_path is not a multi partition disk image, no need to use
# device-mapper.
logging.debug("Release loop dev %s allocated for %s", loop_dev_path,
image_path)
ReleaseBdevPartitionMapping(loop_dev_path)
return None
def ReleaseBdevPartitionMapping(loop_dev_path):
"""Release allocated dm devices and loopback devices.
@type loop_dev_path: string
@param loop_dev_path: path of loopback device returned by
L{CreateBdevPartitionMapping}
"""
result = utils_process.RunCmd(["kpartx", "-d", loop_dev_path])
if result.failed:
raise errors.CommandError(
"Failed to release partition mapping of %s: %s" %
(loop_dev_path, result.output))
result = utils_process.RunCmd(["losetup", "-d", loop_dev_path])
if result.failed:
raise errors.CommandError("Failed to detach %s: %s" %
(loop_dev_path, result.output))