From: Michael Chapman <mike@very.puzzling.org>
Date: Mon, 30 Mar 2015 02:41:00 +0000 (+1100)
Subject: qemu: fix race between disk mirror fail and cancel
X-Git-Tag: v1.2.13.1~18
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9a0e0d3f176b198d4fcec9f00b278c152091d0dd;p=thirdparty%2Flibvirt.git

qemu: fix race between disk mirror fail and cancel

If a VM migration is aborted, a disk mirror may be failed by QEMU before
libvirt has a chance to cancel it. The disk->mirrorState remains at
_ABORT in this case, and this breaks subsequent mirrorings of that disk.

We should instead check the mirrorState directly and transition to _NONE
if it is already aborted. Do the check *after* aborting the block job in
QEMU to avoid a race.

Signed-off-by: Michael Chapman <mike@very.puzzling.org>
(cherry picked from commit e5d729ba42d86eb3afa9799bca2944700fde41bb)
---

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 21432c0b98..39ca37c1a2 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1852,6 +1852,10 @@ qemuMigrationDriveMirror(virQEMUDriverPtr driver,
         } else {
             VIR_WARN("Unable to enter monitor. No block job cancelled");
         }
+
+        /* If disk mirror is already aborted, clear the mirror state now */
+        if (disk->mirrorState == VIR_DOMAIN_DISK_MIRROR_STATE_ABORT)
+            disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_NONE;
     }
     if (err)
         virSetError(err);
@@ -1920,6 +1924,10 @@ qemuMigrationCancelDriveMirror(qemuMigrationCookiePtr mig,
             ret = -1;
             goto cleanup;
         }
+
+        /* If disk mirror is already aborted, clear the mirror state now */
+        if (disk->mirrorState == VIR_DOMAIN_DISK_MIRROR_STATE_ABORT)
+            disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_NONE;
     }
 
  cleanup: