On 1/29/24 2:30 AM, Peter Krempa wrote:
On Thu, Jan 25, 2024 at 14:52:10 -0600, Jonathon Jongsma wrote:
When starting nbdkit processes for the backing store of a disk, we were
returning an error if any backing store failed, but we were not cleaning
up processes that succeeded higher in the chain. Make sure that if we
return a failure status from qemuNbdkitStartStorageSource() that we roll
back any processes that had been started.
qemuNbdkitStartStorageSource is called from:
src/qemu/qemu_extdevice.c=qemuExtDevicesStart(virQEMUDriver *driver,
src/qemu/qemu_extdevice.c: if (qemuNbdkitStartStorageSource(driver, vm, disk->src, true) < 0)
src/qemu/qemu_extdevice.c: if (qemuNbdkitStartStorageSource(driver, vm, def->os.loader->nvram, true) < 0)
The counterpart is qemuExtDevicesStop.
src/qemu/qemu_hotplug.c=qemuDomainAttachDeviceDiskLiveInternal(virQEMUDriver *driver,
src/qemu/qemu_hotplug.c: if (qemuNbdkitStartStorageSource(driver, vm, disk->src, true) < 0)
This has cleanup inline.
Thus I don't see a possibility where what you describe in the commit
message can happen.
Oops it seems that i never actually responded to this comment. Perhaps
because I was waiting for a resolution on patch 3.
The motivation for this patch was actually in anticipation of patch 3.
In that patch, I followed the existing pattern inside of
qemuDomainStorageSourceAccessModify() where we only set a 'revoke_foo'
variable if the initial 'allow' call succeeds. In other words, if a
function like qemuDomainStorageSourceAccessModifyNVMe() fails, we assume
that it has left things in a consistent state and doesn't need to be
revoked in the error path. So I followed the same pattern for this function.
If you think it would be better, I could just squash this patch with
patch 3?
Jonathon
Signed-off-by: Jonathon Jongsma <jjongsma@xxxxxxxxxx>
---
src/qemu/qemu_nbdkit.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/qemu/qemu_nbdkit.c b/src/qemu/qemu_nbdkit.c
index 39f9c58a48..edbe2137d0 100644
--- a/src/qemu/qemu_nbdkit.c
+++ b/src/qemu/qemu_nbdkit.c
@@ -920,8 +920,11 @@ qemuNbdkitStartStorageSource(virQEMUDriver *driver,
return qemuNbdkitStartStorageSourceOne(driver, vm, src);
for (backing = src; backing != NULL; backing = backing->backingStore) {
- if (qemuNbdkitStartStorageSourceOne(driver, vm, backing) < 0)
+ if (qemuNbdkitStartStorageSourceOne(driver, vm, backing) < 0) {
+ /* roll back any previously-started sources */
+ qemuNbdkitStopStorageSource(src, vm, true);
return -1;
+ }
}
return 0;
--
2.43.0
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