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dom0+vm: qvm-block --attach-file

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Allow to attach disk image from different VM as block device. File attached
with qvm-block -A will be visible as loopX device and as such can be detached.
File path will be in device description.
This commit is contained in:
Marek Marczykowski 2012-03-26 20:29:49 +02:00
parent f05605eccc
commit 8105fad646
4 changed files with 48 additions and 13 deletions
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27
dom0/qvm-core/qubesutils.py
View File

@ -142,6 +142,9 @@ def block_name_to_majorminor(name):
elif name.startswith("sr"):
disk = False
major = 11
elif name.startswith("loop"):
disk = False
major = 7
elif name.startswith("md"):
disk = False
major = 9
@ -242,25 +245,34 @@ def block_check_attached(backend_vm, device, backend_xid = None):
vm_list = xs.ls('', '/local/domain/%d/backend/vbd' % backend_xid)
if vm_list is None:
return None
device_majorminor = block_name_to_majorminor(device)
device_majorminor = None
try:
device_majorminor = block_name_to_majorminor(device)
except:
# Unknown devices will be compared directly - perhaps it is a filename?
pass
for vm_xid in vm_list:
for devid in xs.ls('', '/local/domain/%d/backend/vbd/%s' % (backend_xid, vm_xid)):
(tmp_major, tmp_minor) = (0, 0)
phys_device = xs.read('', '/local/domain/%d/backend/vbd/%s/%s/physical-device' % (backend_xid, vm_xid, devid))
dev_params = xs.read('', '/local/domain/%d/backend/vbd/%s/%s/params' % (backend_xid, vm_xid, devid))
if phys_device and phys_device.find(':'):
(tmp_major, tmp_minor) = phys_device.split(":")
tmp_major = int(tmp_major, 16)
tmp_minor = int(tmp_minor, 16)
else:
# perhaps not ready yet - check params
dev_params = xs.read('', '/local/domain/%d/backend/vbd/%s/%s/params' % (backend_xid, vm_xid, devid))
if not dev_params or not dev_params.startswith('/dev/'):
if not dev_params:
# Skip not-phy devices
continue
elif not dev_params.startswith('/dev/'):
# will compare params directly
pass
else:
(tmp_major, tmp_minor) = block_name_to_majorminor(dev_params.lstrip('/dev/'))
if (tmp_major, tmp_minor) == device_majorminor:
if (device_majorminor and (tmp_major, tmp_minor) == device_majorminor) or \
(device_majorminor is None and dev_params == device):
vm_name = xl_ctx.domid_to_name(int(vm_xid))
frontend = block_devid_to_name(int(devid))
return {"xid":int(vm_xid), "frontend": frontend, "devid": int(devid), "vm": vm_name}
@ -290,7 +302,12 @@ def block_attach(vm, backend_vm, device, frontend=None, mode="w", auto_detach=Fa
else:
raise QubesException("Device %s from %s already connected to VM %s as %s" % (device, backend_vm.name, attached_vm['vm'], attached_vm['frontend']))
xl_cmd = [ '/usr/sbin/xl', 'block-attach', vm.name, 'phy:/dev/' + device, frontend, mode, str(backend_vm.xid) ]
if device.startswith('/'):
backend_dev = 'script:file:' + device
else:
backend_dev = 'phy:/dev/' + device
xl_cmd = [ '/usr/sbin/xl', 'block-attach', vm.name, backend_dev, frontend, mode, str(backend_vm.xid) ]
subprocess.check_call(xl_cmd)
def block_detach(vm, frontend = "xvdi", vm_xid = None):

21
dom0/qvm-tools/qvm-block
View File

@ -37,6 +37,8 @@ def main():
parser = OptionParser (usage)
parser.add_option ("-l", "--list", action="store_true", dest="do_list", default=False)
parser.add_option ("-A", "--attach-file", action="store", dest="file_path", default=None,
help="Attach specified file instead of physical device (syntax: qvm-block -A file backend-VM frontend-VM)")
parser.add_option ("-a", "--attach", action="store_true", dest="do_attach", default=False)
parser.add_option ("-d", "--detach", action="store_true", dest="do_detach", default=False)
parser.add_option ("-f", "--frontend", dest="frontend",
@ -48,8 +50,11 @@ def main():
(options, args) = parser.parse_args ()
if options.file_path:
options.do_attach = True
if options.do_list + options.do_attach + options.do_detach > 1:
print >> sys.stderr, "Only one of -l -a -d is allowed!"
print >> sys.stderr, "Only one of -l -a/-A -d is allowed!"
exit (1)
if options.do_attach or options.do_detach:
@ -64,10 +69,16 @@ def main():
vm = qvm_collection.get_vm_by_name(args[1])
if vm is None:
parser.error ("Invalid VM name: %s" % args[1])
dev_list = block_list()
if not args[0] in dev_list.keys():
parser.error ("Invalid device name: %s" % args[0])
dev = dev_list[args[0]]
if options.file_path:
dev = {}
dev['vm'] = args[0]
dev['device'] = options.file_path
dev['mode'] = 'w'
else:
dev_list = block_list()
if not args[0] in dev_list.keys():
parser.error ("Invalid device name: %s" % args[0])
dev = dev_list[args[0]]
backend_vm = qvm_collection.get_vm_by_name(dev['vm'])
assert backend_vm is not None
kwargs = {}

10
misc/block_add_change
View File

@ -16,6 +16,11 @@ if [ -n "`ls -A /sys/$DEVPATH/holders 2> /dev/null`" ]; then
xenstore-rm "$XS_KEY"
exit 0
fi
# ... and "empty" loop devices
if [ "$MAJOR" -eq 7 -a ! -d /sys/$DEVPATH/loop ]; then
xenstore-rm "$XS_KEY"
exit 0
fi
# Special case for CD
if [ "$ID_TYPE" = "cd" ]; then
@ -26,6 +31,11 @@ if [ "$ID_TYPE" = "cd" ]; then
fi
MODE=r
fi
# Special description for loop devices
if [ -d /sys/$DEVPATH/loop ]; then
DESC=$(cat /sys/$DEVPATH/loop/backing_file)
fi
xenstore-write "$XS_KEY/desc" "$DESC" "$XS_KEY/size" "$SIZE" "$XS_KEY/mode" "$MODE"
# Make sure that block backend is loaded

3
misc/qubes_block.rules
View File

@ -6,9 +6,6 @@ SUBSYSTEM!="block", GOTO="qubes_block_end"
# Skip xen-blkfront devices
ENV{MAJOR}=="202", GOTO="qubes_block_end"
# Skip loop devices
ENV{MAJOR}=="7", GOTO="qubes_block_end"
# Skip device-mapper devices
ENV{MAJOR}=="253", GOTO="qubes_block_end"