On Wed, Mar 09, 2011 at 06:45:46PM -0700, Eric Blake wrote:
> This allows direct saves (no compression, no root-squash NFS) to use
> the more efficient fd: migration, which in turn avoids a race where
> qemu exec: migration can sometimes fail because qemu does a generic
> waitpid() that conflicts with the pclose() used by exec:. Further
> patches will solve compression and root-squash NFS.
>
> * src/qemu/qemu_driver.c (qemudDomainSaveFlag): Use new function
> when there is no compression.
> ---
> src/qemu/qemu_driver.c | 26 +++++++++++++++++++++++---
> 1 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 2d11da8..c4d3c85 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -1790,6 +1790,7 @@ static int qemudDomainSaveFlag(struct qemud_driver *driver, virDomainPtr dom,
> int is_reg = 0;
> unsigned long long offset;
> virCgroupPtr cgroup = NULL;
> + virBitmapPtr qemuCaps = NULL;
>
> memset(&header, 0, sizeof(header));
> memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
> @@ -1820,6 +1821,11 @@ static int qemudDomainSaveFlag(struct qemud_driver *driver, virDomainPtr dom,
> }
> }
>
> + if (qemuCapsExtractVersionInfo(vm->def->emulator, vm->def->os.arch,
> + NULL,
> + &qemuCaps) < 0)
> + goto endjob;
> +
> /* Get XML for the domain */
> xml = virDomainDefFormat(vm->def, VIR_DOMAIN_XML_SECURE);
> if (!xml) {
> @@ -1980,10 +1986,23 @@ static int qemudDomainSaveFlag(struct qemud_driver *driver, virDomainPtr dom,
>
> if (header.compressed == QEMUD_SAVE_FORMAT_RAW) {
> const char *args[] = { "cat", NULL };
> + /* XXX gross - why don't we reuse the fd already opened earlier */
> + int fd = -1;
> +
> + if (qemuCapsGet(qemuCaps, QEMU_CAPS_MIGRATE_QEMU_FD) &&
> + priv->monConfig->type == VIR_DOMAIN_CHR_TYPE_UNIX)
> + fd = open(path, O_WRONLY);
Ok, so this is the bit which causes a regression on NFS rootsquash,
if the path isn't readable by root.
> qemuDomainObjEnterMonitorWithDriver(driver, vm);
> - rc = qemuMonitorMigrateToFile(priv->mon,
> - QEMU_MONITOR_MIGRATE_BACKGROUND,
> - args, path, offset);
> + if (fd >= 0 && lseek(fd, offset, SEEK_SET) == offset) {
> + rc = qemuMonitorMigrateToFd(priv->mon,
> + QEMU_MONITOR_MIGRATE_BACKGROUND,
> + fd);
> + } else {
> + rc = qemuMonitorMigrateToFile(priv->mon,
> + QEMU_MONITOR_MIGRATE_BACKGROUND,
> + args, path, offset);
> + }
> + VIR_FORCE_CLOSE(fd);
> qemuDomainObjExitMonitorWithDriver(driver, vm);
> } else {
> const char *prog = qemudSaveCompressionTypeToString(header.compressed);
Daniel
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