Re: [PATCH 2/3] qemu: roll back if not all nbdkit backends are successful
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.
Signed-off-by: Jonathon Jongsma <jjongsma(a)redhat.com>
---
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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