[libvirt] [PATCH 0/4] Fix segfault while redefining snapshots and allow redefinition of external snapshots
This series fixes two issues while redefining snapshots: 1) Segfault when disk alignment of the new snapshot failed (patch 3) 2) Failure to redefine external snapshots. A check was missing to align disks for external snapshots. (patch 4) Peter Krempa (4): snapshot: conf: Make virDomainSnapshotIsExternal more reusable snapshot: qemu: Separate logic blocks with newlines snapshot: qemu: Fix segfault and vanishing snapshots when redefining snapshot: qemu: Allow redefinition of external snapshots src/conf/snapshot_conf.c | 14 ++++++++---- src/conf/snapshot_conf.h | 1 + src/libvirt_private.syms | 1 + src/qemu/qemu_driver.c | 57 +++++++++++++++++++++++++++++++++++------------- 4 files changed, 54 insertions(+), 19 deletions(-) -- 1.8.0.2
Allow to use definition objects with this predicate function. --- src/conf/snapshot_conf.c | 14 ++++++++++---- src/conf/snapshot_conf.h | 1 + src/libvirt_private.syms | 1 + 3 files changed, 12 insertions(+), 4 deletions(-) diff --git a/src/conf/snapshot_conf.c b/src/conf/snapshot_conf.c index 201c586..0c5b005 100644 --- a/src/conf/snapshot_conf.c +++ b/src/conf/snapshot_conf.c @@ -1058,17 +1058,23 @@ cleanup: bool -virDomainSnapshotIsExternal(virDomainSnapshotObjPtr snap) +virDomainSnapshotDefIsExternal(virDomainSnapshotDefPtr def) { int i; - if (snap->def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) + if (def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) return true; - for (i = 0; i < snap->def->ndisks; i++) { - if (snap->def->disks[i].snapshot == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) + for (i = 0; i < def->ndisks; i++) { + if (def->disks[i].snapshot == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) return true; } return false; } + +bool +virDomainSnapshotIsExternal(virDomainSnapshotObjPtr snap) +{ + return virDomainSnapshotDefIsExternal(snap->def); +} diff --git a/src/conf/snapshot_conf.h b/src/conf/snapshot_conf.h index b0f8760..f1d5995 100644 --- a/src/conf/snapshot_conf.h +++ b/src/conf/snapshot_conf.h @@ -166,6 +166,7 @@ int virDomainListSnapshots(virDomainSnapshotObjListPtr snapshots, virDomainSnapshotPtr **snaps, unsigned int flags); +bool virDomainSnapshotDefIsExternal(virDomainSnapshotDefPtr def); bool virDomainSnapshotIsExternal(virDomainSnapshotObjPtr snap); VIR_ENUM_DECL(virDomainSnapshotLocation) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 497d5d3..d063382 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1097,6 +1097,7 @@ virDomainSnapshotAlignDisks; virDomainSnapshotAssignDef; virDomainSnapshotDefFormat; virDomainSnapshotDefFree; +virDomainSnapshotDefIsExternal; virDomainSnapshotDefParseString; virDomainSnapshotDropParent; virDomainSnapshotFindByName; -- 1.8.0.2
On 01/03/2013 06:38 AM, Peter Krempa wrote:
Allow to use definition objects with this predicate function. --- src/conf/snapshot_conf.c | 14 ++++++++++---- src/conf/snapshot_conf.h | 1 + src/libvirt_private.syms | 1 + 3 files changed, 12 insertions(+), 4 deletions(-)
ACK. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
--- src/qemu/qemu_driver.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index b8bb36b..0883a56 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -11365,6 +11365,7 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, goto cleanup; } + if (def->dom && memcmp(def->dom->uuid, domain->uuid, VIR_UUID_BUFLEN)) { virReportError(VIR_ERR_INVALID_ARG, @@ -11372,6 +11373,7 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, def->name, uuidstr); goto cleanup; } + other = virDomainSnapshotFindByName(vm->snapshots, def->name); if (other) { if ((other->def->state == VIR_DOMAIN_RUNNING || @@ -11384,6 +11386,7 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, def->name); goto cleanup; } + if ((other->def->state == VIR_DOMAIN_DISK_SNAPSHOT) != (def->state == VIR_DOMAIN_DISK_SNAPSHOT)) { virReportError(VIR_ERR_INVALID_ARG, @@ -11392,6 +11395,7 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, def->name); goto cleanup; } + if (other->def->dom) { if (def->dom) { if (!virDomainDefCheckABIStability(other->def->dom, @@ -11403,10 +11407,12 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, other->def->dom = NULL; } } + if (other == vm->current_snapshot) { update_current = true; vm->current_snapshot = NULL; } + /* Drop and rebuild the parent relationship, but keep all * child relations by reusing snap. */ virDomainSnapshotDropParent(other); -- 1.8.0.2
On 01/03/2013 06:38 AM, Peter Krempa wrote:
--- src/qemu/qemu_driver.c | 6 ++++++ 1 file changed, 6 insertions(+)
Cosmetic only. ACK. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
When the disk alignment check done while redefining an existing snapshot failed, the qemu driver attempted to free the existing snapshot. As in the cleanup path the definition of the snapshot wasn't assigned, the cleanup code dereferenced a NULL pointer. This patch changes the behavior on error paths while redefining snapshot in two ways: 1) On failure, modifications done on the snapshot definiton object are rolled back. 2) The previous definition of the data isn't freed until it's certain it won't be needed any more. This change avoids the segfault and additionaly the snapshot doesn't vanish if re-definiton fails for some reason. --- src/qemu/qemu_driver.c | 51 +++++++++++++++++++++++++++++++++++--------------- 1 file changed, 36 insertions(+), 15 deletions(-) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 0883a56..4c7558d 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -11408,6 +11408,24 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, } } + if (def->dom) { + if (def->state == VIR_DOMAIN_DISK_SNAPSHOT || + def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) { + align_location = VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL; + align_match = false; + } + + if (virDomainSnapshotAlignDisks(def, align_location, + align_match) < 0) { + /* revert stealing of the snapshot domain definition */ + if (def->dom && !other->def->dom) { + other->def->dom = def->dom; + def->dom = NULL; + } + goto cleanup; + } + } + if (other == vm->current_snapshot) { update_current = true; vm->current_snapshot = NULL; @@ -11417,18 +11435,20 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, * child relations by reusing snap. */ virDomainSnapshotDropParent(other); virDomainSnapshotDefFree(other->def); - other->def = NULL; + other->def = def; + def = NULL; snap = other; - } - if (def->dom) { - if (def->state == VIR_DOMAIN_DISK_SNAPSHOT || - def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) { - align_location = VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL; - align_match = false; + } else { + if (def->dom) { + if (def->state == VIR_DOMAIN_DISK_SNAPSHOT || + def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) { + align_location = VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL; + align_match = false; + } + if (virDomainSnapshotAlignDisks(def, align_location, + align_match) < 0) + goto cleanup; } - if (virDomainSnapshotAlignDisks(def, align_location, - align_match) < 0) - goto cleanup; } } else { /* Easiest way to clone inactive portion of vm->def is via @@ -11463,11 +11483,12 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, goto cleanup; } - if (snap) - snap->def = def; - else if (!(snap = virDomainSnapshotAssignDef(vm->snapshots, def))) - goto cleanup; - def = NULL; + if (!snap) { + if (!(snap = virDomainSnapshotAssignDef(vm->snapshots, def))) + goto cleanup; + + def = NULL; + } if (update_current) snap->def->current = true; -- 1.8.0.2
On 01/03/2013 06:38 AM, Peter Krempa wrote:
When the disk alignment check done while redefining an existing snapshot failed, the qemu driver attempted to free the existing snapshot. As in the cleanup path the definition of the snapshot wasn't assigned, the cleanup code dereferenced a NULL pointer.
This patch changes the behavior on error paths while redefining snapshot in two ways:
1) On failure, modifications done on the snapshot definiton object are
s/definiton/definition/
rolled back.
2) The previous definition of the data isn't freed until it's certain it won't be needed any more.
This change avoids the segfault and additionaly the snapshot doesn't
s/additionaly/additionally/
vanish if re-definiton fails for some reason.
s/re-definiton/redefinition/
--- src/qemu/qemu_driver.c | 51 +++++++++++++++++++++++++++++++++++--------------- 1 file changed, 36 insertions(+), 15 deletions(-)
ACK. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
On 01/04/13 19:26, Eric Blake wrote:
On 01/03/2013 06:38 AM, Peter Krempa wrote:
When the disk alignment check done while redefining an existing snapshot failed, the qemu driver attempted to free the existing snapshot. As in the cleanup path the definition of the snapshot wasn't assigned, the cleanup code dereferenced a NULL pointer.
This patch changes the behavior on error paths while redefining snapshot in two ways:
1) On failure, modifications done on the snapshot definiton object are
s/definiton/definition/
rolled back.
2) The previous definition of the data isn't freed until it's certain it won't be needed any more.
This change avoids the segfault and additionaly the snapshot doesn't
s/additionaly/additionally/
vanish if re-definiton fails for some reason.
s/re-definiton/redefinition/
--- src/qemu/qemu_driver.c | 51 +++++++++++++++++++++ ++++++++++++++--------------- 1 file changed, 36 insertions(+), 15 deletions(-)
The amount typos in my patches is really embarrassing. I should get spell checking support for my editor :/.
ACK.
Thanks for the review. Peter
A redefinition of an external inactive snapshot/checkpoint wasn't possible without this change. --- src/qemu/qemu_driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 4c7558d..3a52b47 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -11410,7 +11410,7 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain, if (def->dom) { if (def->state == VIR_DOMAIN_DISK_SNAPSHOT || - def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) { + virDomainSnapshotDefIsExternal(def)) { align_location = VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL; align_match = false; } -- 1.8.0.2
On 01/03/2013 06:38 AM, Peter Krempa wrote:
A redefinition of an external inactive snapshot/checkpoint wasn't possible without this change. --- src/qemu/qemu_driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 4c7558d..3a52b47 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -11410,7 +11410,7 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain,
if (def->dom) { if (def->state == VIR_DOMAIN_DISK_SNAPSHOT || - def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) { + virDomainSnapshotDefIsExternal(def)) {
ACK. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
On 01/04/13 19:26, Eric Blake wrote:
On 01/03/2013 06:38 AM, Peter Krempa wrote:
A redefinition of an external inactive snapshot/checkpoint wasn't possible without this change. ---
ACK.
I've pushed the series. Thanks for the review. Peter
participants (2)
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Eric Blake -
Peter Krempa