On Thu, 24 Mar 2011 16:46:14 +0800
Hu Tao <hutao@xxxxxxxxxxxxxx> wrote:
> If two or more disks are mapped to the same image file, operating
> on these disks at the same time may corrupt data stored in the
> image file.
>
> changes:
>
> v2:
>
> - allow it for read-only disks
> - compare source files by inode number
>
It doesn't seem that virDomainDiskConflict observes the "shared"
property of a disk definition.
If all the disks are marked as shared, we should say there is no
conflict.
> ---
> src/conf/domain_conf.c | 54
> ++++++++++++++++++++++++++++++++++++++++++++++
> src/conf/domain_conf.h | 2 + src/libvirt_private.syms | 1 +
> src/qemu/qemu_driver.c | 6 +++++
> 4 files changed, 63 insertions(+), 0 deletions(-)
>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 1b02c25..b43dc4a 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -5455,6 +5455,14 @@ static virDomainDefPtr
> virDomainDefParseXML(virCapsPtr caps, if (!disk)
> goto error;
>
> + if (virDomainDiskConflict(disk, def)) {
> + virDomainReportError(VIR_ERR_INTERNAL_ERROR, "%s %s %s",
> + _("source"),
> + disk->src,
> + _("is already mapped to another
> device, "
> + "skip this device."));
> + continue;
> + }
> def->disks[def->ndisks++] = disk;
> }
> VIR_FREE(nodes);
> @@ -9088,3 +9096,49 @@ cleanup:
>
> return ret;
> }
> +
> +bool virDomainDiskConflict(virDomainDiskDefPtr disk, virDomainDefPtr
> def) +{
> + struct stat stat1, stat2;
> + int i;
> +
> + if (!disk->src)
> + return false;
> +
> + if (stat(disk->src, &stat1)) {
> + if (errno != ENOENT) {
> + /* Can't stat file, for safety treate it as conflicted */
> + return true;
> + }
> + }
> +
> + for (i = 0; i < def->ndisks; i++) {
> + if (disk->readonly && def->disks[i]->readonly)
> + continue;
> +
> + if (stat(def->disks[i]->src, &stat2)) {
> + if (errno != ENOENT) {
> + /* Can't stat file, shouldn't happen but for safety
> treate
> + * it as conflicted */
> + return true;
> + }
> + }
> +
> + if (S_ISREG(stat1.st_mode) && S_ISREG(stat2.st_mode)
> + && (stat1.st_ino == stat2.st_ino)
> + && (stat1.st_dev == stat2.st_dev)) {
> + return true;
> + }
> +
> + if (S_ISCHR(stat1.st_mode) && S_ISCHR(stat2.st_mode)
> + && (stat1.st_rdev == stat2.st_rdev)) {
> + return true;
> + }
> +
> + if (S_ISBLK(stat1.st_mode) && S_ISBLK(stat2.st_mode)
> + && (stat1.st_rdev == stat2.st_rdev)) {
> + return true;
> + }
> + }
> + return false;
> +}
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index 9f595d6..78b2f95 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -1350,6 +1350,8 @@ int
> virDomainDiskDefForeachPath(virDomainDiskDefPtr disk, bool
> ignoreOpenFailure, virDomainDiskDefPathIterator iter,
> void *opaque);
> +bool virDomainDiskConflict(virDomainDiskDefPtr disk,
> + virDomainDefPtr def);
>
> typedef const char* (*virLifecycleToStringFunc)(int type);
> typedef int (*virLifecycleFromStringFunc)(const char *type);
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index b4b6c63..17e2ec4 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -237,6 +237,7 @@ virDomainDeviceTypeToString;
> virDomainDiskBusTypeToString;
> virDomainDiskCacheTypeFromString;
> virDomainDiskCacheTypeToString;
> +virDomainDiskConflict;
> virDomainDiskDefAssignAddress;
> virDomainDiskDefForeachPath;
> virDomainDiskDefFree;
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 6f296c9..6de08d3 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4058,6 +4058,12 @@ static int
> qemudDomainAttachDevice(virDomainPtr dom, break;
>
> case VIR_DOMAIN_DISK_DEVICE_DISK:
> + if (virDomainDiskConflict(dev->data.disk, vm->def)) {
> + qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s %s %s",
> + _("source"), dev->data.disk->src,
> + _("is already mapped to another
> device."));
> + break;
> + }
> if (dev->data.disk->bus == VIR_DOMAIN_DISK_BUS_USB) {
> ret = qemuDomainAttachUsbMassstorageDevice(driver,
> vm, dev->data.disk, qemuCaps);
--
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