On Wed, Apr 21, 2010 at 05:56:11PM +0100, Daniel P. Berrange wrote:
> It is possible to use block devices with domain save/restore. Upon
> failure QEMU unlinks the path being saved to. This isn't good when
> it is a block device !
>
> * src/qemu/qemu_driver.c: Don't unlink block devices if save fails
> ---
> src/qemu/qemu_driver.c | 22 ++++++++++++++++++++--
> 1 files changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 91fe963..50cd982 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4787,6 +4787,8 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
> int rc;
> virDomainEventPtr event = NULL;
> qemuDomainObjPrivatePtr priv;
> + struct stat sb;
> + int is_bdev = 0;
>
> memset(&header, 0, sizeof(header));
> memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
> @@ -4840,6 +4842,21 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
> }
> header.xml_len = strlen(xml) + 1;
>
> + /* path might be a pre-existing block dev, in which case
> + * we need to skip the create step, and also avoid unlink
> + * in the failure case */
> + if (stat(path, &sb) < 0) {
> + if (errno != ENOENT) {
> + virReportSystemError(errno, _("unable to access %s"), path);
> + goto endjob;
> + } else {
> + is_bdev = 0;
> + }
what about EACCESS can we fail stat() but still be able to append to
the file ? That sounds unlikely though...
> + } else {
> + is_bdev = S_ISBLK(sb.st_mode);
> + }
> +
> +
> /* Setup hook data needed by virFileOperation hook function */
> hdata.dom = dom;
> hdata.path = path;
> @@ -4849,7 +4866,8 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
> /* Write header to file, followed by XML */
>
> /* First try creating the file as root */
> - if ((rc = virFileOperation(path, O_CREAT|O_TRUNC|O_WRONLY,
> + if (!is_bdev &&
> + (rc = virFileOperation(path, O_CREAT|O_TRUNC|O_WRONLY,
> S_IRUSR|S_IWUSR,
> getuid(), getgid(),
> qemudDomainSaveFileOpHook, &hdata,
> @@ -5014,7 +5032,7 @@ endjob:
>
> cleanup:
> VIR_FREE(xml);
> - if (ret != 0)
> + if (ret != 0 && !is_bdev)
> unlink(path);
> if (vm)
> virDomainObjUnlock(vm);
ACK,
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel@xxxxxxxxxxxx | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/
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