于 2011年09月23日 15:59, Osier Yang 写道:
> $subject + "If the disk is shared and readonly."
s/disk is/disk is not/
>
> If the disk is not shared or readonly, the later started domain
> will relabel the disk, thus the first domain will lose the permission
> to write to the disk and be corrupt.
>
> --
> I'm not sure if it's the design to allow multiple domains use
> same disk not shared and readonly. So this patch just gives a
> demo of the implementation (it skips the checking of nbd disk,
> and only changes qemu driver),
Hmm, preventing the relabeling in security driver instead might be the
more proper way? (If the disk source is used by other *running* domain,
then quit relabeling and exit with error).
However, this won't prevent one using same disk source for multiple domains
if security_driver is disabled.
And if security_driver is disabled, there will be no permission problem, all
the domains can write to the same disk source, thus it might cause
inconsistency
between the domains or corrupt.
> to see whether if the pricinple
> is right or not.
> ---
> src/conf/domain_conf.c | 34 ++++++++++++++++++++++++++++++++++
> src/conf/domain_conf.h | 2 ++
> src/libvirt_private.syms | 1 +
> src/qemu/qemu_driver.c | 24 ++++++++++++++++++++++++
> 4 files changed, 61 insertions(+), 0 deletions(-)
>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 7463d7c..b64450b 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -655,6 +655,40 @@ virDomainObjPtr virDomainFindByName(const virDomainObjListPtr doms,
> return obj;
> }
>
> +static int
> +virDomainObjListSearchDiskPath(const void *payload,
> + const void *name ATTRIBUTE_UNUSED,
> + const void *data)
> +{
> + virDomainObjPtr obj = (virDomainObjPtr)payload;
> + int i;
> + int want = 0;
> + const char *path = NULL;
> +
> + path = (const char *)data;
> +
> + virDomainObjLock(obj);
> + for (i = 0; obj->def->ndisks; i++) {
> + if (STREQ(obj->def->disks[i]->src, path)) {
> + want = 1;
> + break;
> + }
> + }
> + virDomainObjUnlock(obj);
> +
> + return want;
> +}
> +
> +virDomainObjPtr
> +virDomainFindByDiskPath(const virDomainObjListPtr doms,
> + const char *path)
> +{
> + virDomainObjPtr obj = NULL;
> + obj = virHashSearch(doms->objs, virDomainObjListSearchDiskPath, path);
> + if (obj)
> + virDomainObjLock(obj);
> + return obj;
> +}
>
> bool virDomainObjTaint(virDomainObjPtr obj,
> enum virDomainTaintFlags taint)
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index 371f270..d7d42dd 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -1549,6 +1549,8 @@ virDomainObjPtr virDomainFindByUUID(const virDomainObjListPtr doms,
> const unsigned char *uuid);
> virDomainObjPtr virDomainFindByName(const virDomainObjListPtr doms,
> const char *name);
> +virDomainObjPtr virDomainFindByDiskPath(const virDomainObjListPtr doms,
> + const char *path);
>
> bool virDomainObjTaint(virDomainObjPtr obj,
> enum virDomainTaintFlags taint);
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 8235ea1..c33cb2d 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -302,6 +302,7 @@ virDomainFSTypeToString;
> virDomainFindByID;
> virDomainFindByName;
> virDomainFindByUUID;
> +virDomainFindByDiskPath;
> virDomainGetRootFilesystem;
> virDomainGraphicsAuthConnectedTypeFromString;
> virDomainGraphicsAuthConnectedTypeToString;
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 0d0bea2..a448a0b 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4796,6 +4796,7 @@ static virDomainPtr qemudDomainDefine(virConnectPtr conn, const char *xml) {
> virDomainPtr dom = NULL;
> virDomainEventPtr event = NULL;
> int dupVM;
> + int i;
>
> qemuDriverLock(driver);
> if (!(def = virDomainDefParseString(driver->caps, xml,
> @@ -4809,6 +4810,29 @@ static virDomainPtr qemudDomainDefine(virConnectPtr conn, const char *xml) {
> if ((dupVM = virDomainObjIsDuplicate(&driver->domains, def, 0)) < 0)
> goto cleanup;
>
> + /* Make sure no disk is used by other domain, if it's not
> + * either shareable or readonly.
> + */
> + for (i = 0; i < def->ndisks; i++) {
> + /* XXX: Do we also need to check if same host&port is used by
> + * other domain for disk of nbd type?
> + */
> + if (def->disks[i]->type == VIR_DOMAIN_DISK_TYPE_NETWORK &&
> + def->disks[i]->protocol == VIR_DOMAIN_DISK_PROTOCOL_NBD)
> + continue;
> +
> + if (!def->disks[i]->shared &&
> + !def->disks[i]->readonly &&
> + (vm = virDomainFindByDiskPath(&driver->domains,
> + def->disks[i]->src))
> ) {
> + qemuReportError(VIR_ERR_INVALID_ARG,
> + _("disk '%s' already used by domain '%s'"),
> + def->disks[i]->src,
> + vm->def->name);
> + goto cleanup;
> + }
> + }
> +
> if (qemudCanonicalizeMachine(driver, def) < 0)
> goto cleanup;
>
--
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