vishesh92 opened a new issue, #14695:
URL: https://github.com/apache/cloudstack/issues/14695
### problem
When a LUKS-encrypted volume on StorPool primary storage is resized, the
plugin resizes the StorPool volume to exactly the requested size. At creation
the plugin adds 2 MiB (2097152 bytes) for the LUKS header, but the resize
path
does not.
Effects:
1. Live resize fails inside QEMU. The agent runs `virsh blockresize` with the
new size; QEMU needs new size + LUKS payload offset on the underlying
block
device, which is larger than the device, and returns:
```
internal error: unable to execute QEMU command 'block_resize': Cannot
grow device files
```
The failure is not surfaced. `notifyqemu()` in `resizevolume.sh` only logs
"failed to live resize", the script exits 0, the agent returns success and
the resizeVolume job succeeds. The guest keeps seeing the old size.
2. Size mismatch. CloudStack records the requested size, but once QEMU
re-reads the device (VM stop/start, or a manual blockresize) the guest
sees
the requested size minus the LUKS header. The same shortfall applies to
offline resize, without any error (from code reading, not tested).
3. Rollback uses the same unadjusted size (from code reading, not tested).
If the StorPool API call or the agent command fails, `resizeVolume()`
calls
`StorPoolUtil.volumeUpdate(name, oldSize, true, ...)`, i.e. shrinkOk=true
with the CloudStack size. For an encrypted volume that has never been
resized the device is oldSize + 2097152, so this requests a 2 MiB shrink
of
a LUKS device.
Code references (main at cc30155defc89bce24a253df892a0494ae8bba1e):
- Create adds the allowance:
https://github.com/apache/cloudstack/blob/cc30155defc89bce24a253df892a0494ae8bba1e/plugins/storage/volume/storpool/src/main/java/org/apache/cloudstack/storage/datastore/driver/StorPoolPrimaryDataStoreDriver.java#L302
(also L876 and L879 for volumes created from a template/snapshot)
- Resize does not (`updateVolumeByStorPoolQoS`, `updateVolumeByOffering`):
https://github.com/apache/cloudstack/blob/cc30155defc89bce24a253df892a0494ae8bba1e/plugins/storage/volume/storpool/src/main/java/org/apache/cloudstack/storage/datastore/driver/StorPoolPrimaryDataStoreDriver.java#L495-L512
- Rollback with oldSize and shrinkOk=true:
https://github.com/apache/cloudstack/blob/cc30155defc89bce24a253df892a0494ae8bba1e/plugins/storage/volume/storpool/src/main/java/org/apache/cloudstack/storage/datastore/driver/StorPoolPrimaryDataStoreDriver.java#L420-L436
- QEMU side: `block_crypto_co_truncate` adds the payload offset, and
`raw_co_truncate` rejects growth of a block device:
https://github.com/qemu/qemu/blob/v9.0.0/block/crypto.c#L433-L449
https://github.com/qemu/qemu/blob/v9.0.0/block/file-posix.c#L2670-L2678
The header allowance was introduced with StorPool encryption support in
#7539.
### versions
on all versions
### The steps to reproduce the bug
1. KVM zone with StorPool primary storage and a host that supports volume
encryption. Create a custom-size disk offering with encrypt=true, tagged
to the StorPool pool.
2. Create a 10 GiB data volume from that offering and attach it to a running
VM. On the host, `blockdev --getsize64` on the StorPool device shows
10739515392 (10 GiB + 2097152); the guest sees 10737418240.
3. Resize the volume while the VM is running:
cmk resize volume id=<volume-uuid> size=20
4. Observe:
- the resizeVolume job succeeds and CloudStack reports 20 GiB
- `blockdev --getsize64` shows 21474836480 (exactly 20 GiB, no allowance)
- libvirtd logs the block_resize "Cannot grow device files" error
- the guest still sees 10 GiB
Expected: the StorPool volume is resized to 20 GiB + 2097152, blockresize
succeeds, and the guest sees 20 GiB, matching what CloudStack reports.
### What to do about it?
Apply the same allowance on resize as on create, for encrypted volumes only:
- In `updateVolumeByOffering` and `updateVolumeByStorPoolQoS`, send
`payload.newSize + 2097152` to the StorPool API when the volume has a
passphrase (or KMS key on main). `updateVolumeByStorPoolQoS` needs the
volume passed in.
- Use the same adjusted size for the rollback in `resizeVolume()`.
- Keep `payload.newSize` for the agent command and for the size stored in
the database.
Sketch:
```java
private static long getStorPoolVolumeSize(VolumeObject vol, long size) {
boolean encrypted = vol.getPassphraseId() != null || vol.getKmsKeyId()
!= null;
return encrypted ? size + 2097152 : size;
}
```
Volumes already resized under this bug have no allowance; the next resize
after the fix would correct them.
Separately, it may be worth surfacing the blockresize failure instead of
returning success, so a failed live resize is visible in the job result.
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