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[Qemu-devel] [PATCH] loadvm: improve tests before bdrv_snapshot_goto()
From: |
Miguel Di Ciurcio Filho |
Subject: |
[Qemu-devel] [PATCH] loadvm: improve tests before bdrv_snapshot_goto() |
Date: |
Wed, 14 Jul 2010 15:27:31 -0300 |
This patch improves the resilience of the load_vmstate() function, doing
further and better ordered tests.
In load_vmstate(), if there is any error on bdrv_snapshot_goto(), except if the
error is on VM state device, load_vmstate() will return zero and the VM will be
started with major corruption chances.
The current process:
- test if there is any writable device without snapshot support
- if exists return -error
- get the device that saves the VM state, possible return -error but unlikely
because it was tested earlier
- flush I/O
- run bdrv_snapshot_goto() on devices
- if fails, give an warning and goes to the next (not good!)
- if fails on the VM state device, return zero (not good!)
- check if the requested snapshot exists on the device that saves the VM state
and the state is not zero
- if fails return -error
- open the file with the VM state
- if fails return -error
- load the VM state
- if fails return -error
- return zero
New behavior:
- get the device that saves the VM state
- if fails return -error
- check if the requested snapshot exists on the device that saves the VM state
and the state is not zero
- if fails return -error
- test if there is any writable device without snapshot support
- if exists return -error
- test if the devices with snapshot support have the requested snapshot
- if anyone fails, return -error
- flush I/O
- run snapshot_goto() on devices
- if anyone fails, return -error
- open the file with the VM state
- if fails return -error
- load the VM state
- if fails return -error
- return zero
do_loadvm must not call vm_start if any error has occurred in load_vmstate.
Signed-off-by: Miguel Di Ciurcio Filho <address@hidden>
---
monitor.c | 3 +-
savevm.c | 71 ++++++++++++++++++++++++++++--------------------------------
2 files changed, 35 insertions(+), 39 deletions(-)
diff --git a/monitor.c b/monitor.c
index 45fd482..aa60cfa 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2270,8 +2270,9 @@ static void do_loadvm(Monitor *mon, const QDict *qdict)
vm_stop(0);
- if (load_vmstate(name) >= 0 && saved_vm_running)
+ if (load_vmstate(name) == 0 && saved_vm_running) {
vm_start();
+ }
}
int monitor_get_fd(Monitor *mon, const char *fdname)
diff --git a/savevm.c b/savevm.c
index ee27989..9f29cb0 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1804,12 +1804,25 @@ void do_savevm(Monitor *mon, const QDict *qdict)
int load_vmstate(const char *name)
{
- BlockDriverState *bs, *bs1;
+ BlockDriverState *bs, *bs_vm_state;
QEMUSnapshotInfo sn;
QEMUFile *f;
int ret;
- /* Verify if there is a device that doesn't support snapshots and is
writable */
+ bs_vm_state = bdrv_snapshots();
+ if (!bs_vm_state) {
+ error_report("No block device supports snapshots");
+ return -EINVAL;
+ }
+
+ /* Don't even try to load empty VM states */
+ ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
+ if ((ret >= 0) && (sn.vm_state_size == 0)) {
+ return -EINVAL;
+ }
+
+ /* Verify if there is any device that doesn't support snapshots and is
+ writable and check if the requested snapshot is available too. */
bs = NULL;
while ((bs = bdrv_next(bs))) {
@@ -1821,64 +1834,46 @@ int load_vmstate(const char *name)
error_report("Device '%s' is writable but does not support
snapshots.",
bdrv_get_device_name(bs));
return -ENOTSUP;
+ } else {
+ ret = bdrv_snapshot_find(bs, &sn, name);
+ if (ret < 0) {
+ error_report("Device '%s' does not have the requested snapshot
'%s'",
+ bdrv_get_device_name(bs), name);
+ return ret;
+ }
}
}
- bs = bdrv_snapshots();
- if (!bs) {
- error_report("No block device supports snapshots");
- return -EINVAL;
- }
-
/* Flush all IO requests so they don't interfere with the new state. */
qemu_aio_flush();
- bs1 = NULL;
- while ((bs1 = bdrv_next(bs1))) {
- if (bdrv_can_snapshot(bs1)) {
- ret = bdrv_snapshot_goto(bs1, name);
+ bs = NULL;
+ while ((bs = bdrv_next(bs))) {
+ if (bdrv_can_snapshot(bs)) {
+ ret = bdrv_snapshot_goto(bs, name);
if (ret < 0) {
- switch(ret) {
- case -ENOTSUP:
- error_report("%sSnapshots not supported on device '%s'",
- bs != bs1 ? "Warning: " : "",
- bdrv_get_device_name(bs1));
- break;
- case -ENOENT:
- error_report("%sCould not find snapshot '%s' on device
'%s'",
- bs != bs1 ? "Warning: " : "",
- name, bdrv_get_device_name(bs1));
- break;
- default:
- error_report("%sError %d while activating snapshot on
'%s'",
- bs != bs1 ? "Warning: " : "",
- ret, bdrv_get_device_name(bs1));
- break;
- }
- /* fatal on snapshot block device */
- if (bs == bs1)
- return 0;
+ error_report("Error %d while activating snapshot '%s' on '%s'",
+ ret, name, bdrv_get_device_name(bs));
+ return ret;
}
}
}
- /* Don't even try to load empty VM states */
- ret = bdrv_snapshot_find(bs, &sn, name);
- if ((ret >= 0) && (sn.vm_state_size == 0))
- return -EINVAL;
-
/* restore the VM state */
- f = qemu_fopen_bdrv(bs, 0);
+ f = qemu_fopen_bdrv(bs_vm_state, 0);
if (!f) {
error_report("Could not open VM state file");
return -EINVAL;
}
+
ret = qemu_loadvm_state(f);
+
qemu_fclose(f);
if (ret < 0) {
error_report("Error %d while loading VM state", ret);
return ret;
}
+
return 0;
}
--
1.7.1
- [Qemu-devel] [PATCH] loadvm: improve tests before bdrv_snapshot_goto(),
Miguel Di Ciurcio Filho <=