Fix GC hidden attribute in case of SIGTERM signal #87
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The GC can be interrupted by a SIGTERM signal. If this is caught while modifying
a volume's hidden flag, this can have bad consequences.
For example in the situation below, the hidden flag of a volume has been changed
but the cached value (self.hidden) in the python process still has the old value
because of the 'util.CommandException' exception that was thrown. A VDI
that normally should not be hidden is still hidden after executing
`_undoInterruptedCoalesceLeaf` because the hidden value was not the correct one.
Code:
```
def _setHidden(self, hidden=True):
vhdutil.setHidden(self.path, hidden)
# Exception! Next line is never executed.
self.hidden = hidden
```
Trace:
```
Jun 5 09:15:50 r620-q6 SMGC: [563219] Removed vhd-parent from dce4b0fc(2.000G/170.336M?)
Jun 5 09:15:50 r620-q6 SMGC: [563219] Removed vhd-blocks from dce4b0fc(2.000G/170.336M?)
Jun 5 09:15:50 r620-q6 SM: [563219] ['/usr/bin/vhd-util', 'set', '--debug', '-n', '/var/run/sr-mount/f816795d-e7a9-43df-170c-23bc329607fc/OLD_dce4b0fc-6ad1-4750-857b-45d8d2758503.vhd', '-f', 'hidden', '-v', '1']
Jun 5 09:15:50 r620-q6 SM: [563219] GC: recieved SIGTERM
Jun 5 09:15:50 r620-q6 SM: [563219] FAILED in util.pread: (rc -15) stdout: '', stderr: ''
Jun 5 09:15:50 r620-q6 SMGC: [563219] *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jun 5 09:15:50 r620-q6 SMGC: [563219] ***********************
Jun 5 09:15:50 r620-q6 SMGC: [563219] * E X C E P T I O N *
Jun 5 09:15:50 r620-q6 SMGC: [563219] ***********************
Jun 5 09:15:50 r620-q6 SMGC: [563219] _doCoalesceLeaf: EXCEPTION <class 'util.CommandException'>, Signalled 15
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/cleanup.py", line 2653, in _liveLeafCoalesce
Jun 5 09:15:50 r620-q6 SMGC: [563219] self._doCoalesceLeaf(vdi)
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/cleanup.py", line 2717, in _doCoalesceLeaf
Jun 5 09:15:50 r620-q6 SMGC: [563219] vdi._setHidden(True)
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/cleanup.py", line 1063, in _setHidden
Jun 5 09:15:50 r620-q6 SMGC: [563219] vhdutil.setHidden(self.path, hidden)
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/vhdutil.py", line 235, in setHidden
Jun 5 09:15:50 r620-q6 SMGC: [563219] ret = ioretry(cmd)
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/vhdutil.py", line 94, in ioretry
Jun 5 09:15:50 r620-q6 SMGC: [563219] errlist=[errno.EIO, errno.EAGAIN])
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/util.py", line 347, in ioretry
Jun 5 09:15:50 r620-q6 SMGC: [563219] return f()
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/vhdutil.py", line 93, in <lambda>
Jun 5 09:15:50 r620-q6 SMGC: [563219] return util.ioretry(lambda: util.pread2(cmd, text=text),
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/util.py", line 255, in pread2
Jun 5 09:15:50 r620-q6 SMGC: [563219] return pread(cmdlist, quiet=quiet, text=text)
Jun 5 09:15:50 r620-q6 SMGC: [563219] File "/opt/xensource/sm/util.py", line 217, in pread
Jun 5 09:15:50 r620-q6 SMGC: [563219] raise CommandException(rc, str(cmdlist), stderr.strip())
Jun 5 09:15:50 r620-q6 SMGC: [563219]
Jun 5 09:15:50 r620-q6 SMGC: [563219] *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jun 5 09:15:50 r620-q6 SMGC: [563219] *** UNDO LEAF-COALESCE
Jun 5 09:15:50 r620-q6 SMGC: [563219] Renaming parent back: dce4b0fc-6ad1-4750-857b-45d8d2758503 -> 056b6f93-66ff-460a-9354-157540b584a8
Jun 5 09:15:50 r620-q6 SMGC: [563219] Renaming /var/run/sr-mount/f816795d-e7a9-43df-170c-23bc329607fc/dce4b0fc-6ad1-4750-857b-45d8d2758503.vhd -> /var/run/sr-mount/f816795d-e7a9-43df-170c-23bc329607fc/056b6f93-66ff-460a-9354-157540b584a8.vhd
Jun 5 09:15:50 r620-q6 SMGC: [563219] Renaming child back to dce4b0fc-6ad1-4750-857b-45d8d2758503
Jun 5 09:15:50 r620-q6 SMGC: [563219] Renaming /var/run/sr-mount/f816795d-e7a9-43df-170c-23bc329607fc/OLD_dce4b0fc-6ad1-4750-857b-45d8d2758503.vhd -> /var/run/sr-mount/f816795d-e7a9-43df-170c-23bc329607fc/dce4b0fc-6ad1-4750-857b-45d8d2758503.vhd
Jun 5 09:15:50 r620-q6 SMGC: [563219] Updating the VDI record
Jun 5 09:15:50 r620-q6 SMGC: [563219] Set vhd-parent = 056b6f93-66ff-460a-9354-157540b584a8 for dce4b0fc(2.000G/8.500K?)
Jun 5 09:15:50 r620-q6 SMGC: [563219] Set vdi_type = vhd for dce4b0fc(2.000G/8.500K?)
Jun 5 09:15:50 r620-q6 SM: [563219] ['/usr/bin/vhd-util', 'set', '--debug', '-n', '/var/run/sr-mount/f816795d-e7a9-43df-170c-23bc329607fc/056b6f93-66ff-460a-9354-157540b584a8.vhd', '-f', 'hidden', '-v', '1']
Jun 5 09:15:50 r620-q6 SM: [563219] pread SUCCESS
Jun 5 09:15:50 r620-q6 SMGC: [563219] *** leaf-coalesce undo successful
```
Therefore, a VDI impacted by this problem remains hidden and can no longer
be used correctly without manual intervention:
```
Jun 5 09:16:29 r620-q6 SM: [566174] lock: released /var/lock/sm/f816795d-e7a9-43df-170c-23bc329607fc/sr
Jun 5 09:16:29 r620-q6 SM: [566174] ***** generic exception: vdi_clone: EXCEPTION <class 'xs_errors.SROSError'>, Failed to clone VDI [opterr=hidden VDI]
Jun 5 09:16:29 r620-q6 SM: [566174] File "/opt/xensource/sm/SRCommand.py", line 113, in run
Jun 5 09:16:29 r620-q6 SM: [566174] return self._run_locked(sr)
Jun 5 09:16:29 r620-q6 SM: [566174] File "/opt/xensource/sm/SRCommand.py", line 163, in _run_locked
Jun 5 09:16:29 r620-q6 SM: [566174] rv = self._run(sr, target)
Jun 5 09:16:29 r620-q6 SM: [566174] File "/opt/xensource/sm/SRCommand.py", line 270, in _run
Jun 5 09:16:29 r620-q6 SM: [566174] return target.clone(self.params['sr_uuid'], self.vdi_uuid)
Jun 5 09:16:29 r620-q6 SM: [566174] File "/opt/xensource/sm/FileSR.py", line 704, in clone
Jun 5 09:16:29 r620-q6 SM: [566174] return self._do_snapshot(sr_uuid, vdi_uuid, VDI.SNAPSHOT_DOUBLE)
Jun 5 09:16:29 r620-q6 SM: [566174] File "/opt/xensource/sm/FileSR.py", line 754, in _do_snapshot
Jun 5 09:16:29 r620-q6 SM: [566174] return self._snapshot(snapType, cbtlog, consistency_state)
Jun 5 09:16:29 r620-q6 SM: [566174] File "/opt/xensource/sm/FileSR.py", line 797, in _snapshot
Jun 5 09:16:29 r620-q6 SM: [566174] raise xs_errors.XenError('VDIClone', opterr='hidden VDI')
Jun 5 09:16:29 r620-q6 SM: [566174]
```
Signed-off-by: Ronan Abhamon <[email protected]>
|
Is this a candidate for an upstream PR? |
Nambrok
approved these changes
Jun 11, 2025
|
Upstream PR: xapi-project#760 |
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The GC can be interrupted by a SIGTERM signal. If this is caught while modifying a volume's hidden flag, this can have bad consequences.
For example in the situation below, the hidden flag of a volume has been changed but the cached value (self.hidden) in the python process still has the old value because of the 'util.CommandException' exception that was thrown. A VDI that normally should not be hidden is still hidden after executing
_undoInterruptedCoalesceLeafbecause the hidden value was not the correct one.Code:
Trace:
Therefore, a VDI impacted by this problem remains hidden and can no longer be used correctly without manual intervention: