Re: [libvirt] [PATCH 2/4] Avoid create/unlink with block devs used for QEMU save

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; + }

+ } 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);