*Hello,
I've checked the duplicate-check code here and I found that's checked
only in the context of one domain but not cross-domain. The thing is
that we should check tap/vbd device cross-domain not to allow another
guest to use the same disk image in some circumstances to prevent VM's
disk corruption.
The patch included denies disk image addition under those circumstances:
1. **We're adding read-only disk that's already used as write-exclusive
2. **We're adding write-shared disk that's already used as write-exclusive
3. **We're adding write-exclusive disk that's already used
4. **We're adding read-only disk that's already used as write-shared*
(because of I/O caching issues etc.)
*
The vif device duplicate check remains the same it was and it's checked
in the context of current domain only so that behaviour has been preserved.
Michal
Signed-off-by: Michal Novotny <minovotn@xxxxxxxxxx>
*
diff -r 2522cc95efd2 tools/python/xen/xend/XendConfig.py
--- a/tools/python/xen/xend/XendConfig.py Mon May 11 13:52:04 2009 +0100
+++ b/tools/python/xen/xend/XendConfig.py Fri May 15 10:58:25 2009 +0200
@@ -19,6 +19,7 @@
import re
import time
import types
+import XendDomain
from xen.xend import sxp
from xen.xend import uuid
@@ -1160,65 +1161,142 @@
return None
return devid
+ def device_tuple_value_from_dev_info(self, dev_info, key):
+ for x in dev_info:
+ if (type(x) != str):
+ for xx in x:
+ if (xx[0] == key):
+ return xx[1]
+ return None
+
+ # This function translates all block device modes (incl. aliases) to
+ # one common label per each device mode. Those modes can be:
+ # read-only (ro), write-exclusive (wx) and write-shared (ws)
+ def block_device_mode_translate(self, mode):
+ # Device modes can be read-only (ro), write-exclusive (wx) or
+ # write-shared (ws), otherwise an error is raised
+ if mode == "w" or mode == "wr":
+ return "wx"
+ elif mode == "r" or mode == "ro":
+ return "ro"
+ elif mode == "!" or mode == "w!":
+ return "ws"
+
+ # If no mode defined we consider this as write-exclusive
+ return "wx"
+
+ # Detect device duplicates for vbd, tap and vif devices for domain and
+ # duplicate unames in global context not to destroy virtual block devices
def device_duplicate_check(self, dev_type, dev_info, defined_config,
config):
- defined_devices_sxpr = self.all_devices_sxpr(target = defined_config)
-
- if dev_type == 'vbd' or dev_type == 'tap':
- dev_uname = dev_info.get('uname')
- blkdev_name = dev_info.get('dev')
- devid = self._blkdev_name_to_number(blkdev_name)
- if devid == None or dev_uname == None:
- return
-
- for o_dev_type, o_dev_info in defined_devices_sxpr:
- if o_dev_type == 'vbd' or o_dev_type == 'tap':
- blkdev_file = blkdev_uname_to_file(dev_uname)
- o_dev_uname = sxp.child_value(o_dev_info, 'uname')
- if o_dev_uname != None:
- o_blkdev_file = blkdev_uname_to_file(o_dev_uname)
- if blkdev_file == o_blkdev_file:
- raise XendConfigError('The file "%s" is already
used' %
- blkdev_file)
- if dev_uname == o_dev_uname:
- raise XendConfigError('The uname "%s" is already
defined' %
- dev_uname)
- o_blkdev_name = sxp.child_value(o_dev_info, 'dev')
- o_devid = self._blkdev_name_to_number(o_blkdev_name)
- if o_devid != None and devid == o_devid:
- name_array = blkdev_name.split(':', 2)
- if len(name_array) == 2 and name_array[1] == 'cdrom':
- #
- # Since the device is a cdrom, we are most likely
- # inserting, changing, or removing a cd. We can
- # update the old device instead of creating a new
- # one.
- #
- if o_dev_uname != None and dev_uname == None:
- #
- # We are removing a cd. We can simply update
- # the uname on the existing device.
- #
- merge_sxp = sxp.from_string("('vbd' ('uname'
''))")
- else:
- merge_sxp = config
+ # Enumerate all devices for all domains
+ allSxprs = []
+ val = XendDomain.instance().domains.values()
+ for v in val:
+ sxpr = v.getDeviceSxprs(dev_type)
+ for key in sxpr:
+ try:
+ index = allSxprs.index(key)
+ except:
+ allSxprs.append(key)
- dev_uuid = sxp.child_value(o_dev_info, 'uuid')
- if dev_uuid != None and \
- self.device_update(dev_uuid, cfg_sxp =
merge_sxp):
- return dev_uuid
+ # Enumerate devices for current domain
+ sxpr = self.all_devices_sxpr(target = defined_config)
- raise XendConfigError('The device "%s" is already
defined' %
- blkdev_name)
-
- elif dev_type == 'vif':
- dev_mac = dev_info.get('mac')
-
- for o_dev_type, o_dev_info in defined_devices_sxpr:
- if dev_type == o_dev_type:
- if dev_mac.lower() == sxp.child_value(o_dev_info,
'mac').lower():
- raise XendConfigError('The mac "%s" is already
defined' %
- dev_mac)
- return None
+ # For vif interface we won't check cross-domain
+ if sxpr == None and dev_type == 'vif':
+ return
+
+ # Preset None values to all variables we'll be checking
+ new_uname = None
+ uname = None
+ dev = None
+ mac = None
+ mode = None
+
+ # Disk device
+ if dev_type in ['vbd', 'tap']:
+ for x in config:
+ if type(x) != str and (x[0] in ['uname', 'dev', 'mode']):
+ if x[0] == 'uname':
+ new_uname = x[1]
+ if x[0] == 'dev':
+ dev = x[1]
+ if x[0] == 'mode':
+ mode = x[1]
+
+ # If we don't have uname entry (happens in virt-manager) return
+ if new_uname == None:
+ return
+
+ new_uname = new_uname.split(":")[len(new_uname.split(":"))-1]
+ # We need to allow when uname is zero length, eg. hdc:cdrom device
+ if len(new_uname) == 0:
+ log.debug("Null uname when attaching disk device, allowing
%s..."
+ % dev)
+ return
+
+ log.debug("Checking for duplicate for uname: %s, dev: %s, mode:
%s"
+ % (new_uname, dev, mode))
+ # No device in dev found
+ if dev == None:
+ return
+
+ devid = self._blkdev_name_to_number(dev)
+ if devid == None:
+ return
+
+ for o_dev_info in sxpr:
+ # Get information only for tap/vbd block devices
+ if o_dev_info[0] in ['tap', 'vbd']:
+ uname = self.device_tuple_value_from_dev_info(o_dev_info,
"uname")
+ dev = self.device_tuple_value_from_dev_info(o_dev_info,
"dev")
+ dev_uname = None
+ if uname != None:
+ dev_uname = uname.split(":")[len(uname.split(":"))-1]
+ if new_uname == dev_uname:
+ raise XendConfigError('The uname "%s" is already
defined' %
+ dev_uname)
+
+ blkdev = dev.split(":")[0]
+ blkdevid = self._blkdev_name_to_number(blkdev)
+ if blkdevid != None and devid == blkdevid:
+ raise XendConfigError('The device "%s" is already
defined' %
+ blkdev)
+
+ tMode = self.block_device_mode_translate(mode)
+
+ # Device/uname not found in the context of current domain but we
+ # need to have a look to global context. We deny addition of
device
+ # in those cases:
+ # 1. We're adding read-only disk that's already used as
write-exclusive
+ # 2. We're adding write-shared disk that's already used as
write-exclusive
+ # 3. We're adding write-exclusive disk that's already used
+ # 4. We're adding read-only disk that's already used as
write-shared
+ for o_dev_info in allSxprs:
+ backend = self.device_tuple_value_from_dev_info(o_dev_info,
"backend")
+ params = xstransact.Read(backend, "params")
+ aMode = self.block_device_mode_translate(
+ xstransact.Read(backend, "mode") )
+ dev_uname = params.split(":")[len(params.split(":"))-1]
+ if new_uname == dev_uname:
+ if ((tMode == "ro" and aMode == "wx")
+ or (tMode == "ws" and aMode == "wx")
+ or (tMode == "ro" and aMode == "ws")
+ or (tMode == "wx")):
+ raise XendConfigError('The uname "%s" is already used
by another domain' %
+ dev_uname)
+
+ # Virtual network adapter
+ elif dev_type == 'vif':
+ dev_mac = dev_info.get('mac')
+
+ for o_dev_type, o_dev_info in sxpr:
+ if dev_type == o_dev_type:
+ if dev_mac.lower() == sxp.child_value(o_dev_info,
'mac').lower():
+ raise XendConfigError('The mac "%s" is already
defined' %
+ dev_mac)
+
+ return None
def device_add(self, dev_type, cfg_sxp = None, cfg_xenapi = None,
target = None):
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