On Mon, Feb 18, 2013 at 15:38:42 +0100, Michal Privoznik wrote:
> With new NBD storage migration approach there are several
> requirements that need to be meet for successful use of the
s/meet/met/
> feature. One of them is - the file representing a disk, needs to
> have at least same size as on the source. Hence, we must transfer
> a list of pairs [disk target, size] and check on destination that
> this requirement is met and/or take actions to meet it.
> ---
> src/qemu/qemu_migration.c | 302 +++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 288 insertions(+), 14 deletions(-)
>
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index e2c7804..9b38a0c 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
...
> @@ -525,22 +555,71 @@ qemuMigrationCookieAddNetwork(qemuMigrationCookiePtr mig,
>
> static int
> qemuMigrationCookieAddNBD(qemuMigrationCookiePtr mig,
> - virQEMUDriverPtr driver ATTRIBUTE_UNUSED,
> + virQEMUDriverPtr driver,
> virDomainObjPtr vm)
> {
> qemuDomainObjPrivatePtr priv = vm->privateData;
> + int ret = -1;
> + size_t i;
>
> /* It is not a bug if there already is a NBD data */
> if (!mig->nbd &&
> VIR_ALLOC(mig->nbd) < 0) {
> virReportOOMError();
> - return -1;
> + return ret;
> + }
> +
> + /* in Begin phase add info about disks */
> + if (priv->job.phase == QEMU_MIGRATION_PHASE_BEGIN3 &&
> + vm->def->ndisks) {
> + if (VIR_ALLOC_N(mig->nbd->disk, vm->def->ndisks) < 0) {
> + virReportOOMError();
> + goto cleanup;
> + }
> +
> + for (i = 0; i < vm->def->ndisks; i++) {
> + virDomainDiskDefPtr disk = vm->def->disks[i];
> + virDomainBlockInfo info;
> + int format = disk->format;
> +
> + /* Add only non-shared RW disks with source */
> + if (!disk->src || disk->shared || disk->readonly)
> + continue;
> +
> + memset(&info, 0, sizeof(info));
> +
> + if (qemuDomainGetDiskBlockInfo(driver, vm, disk, &info) < 0)
> + goto cleanup;
Hmm, I see solving the need to enter a job for getting disk block info
won't be exactly easy.
> +
> + if (format != VIR_STORAGE_FILE_RAW &&
> + format != VIR_STORAGE_FILE_QCOW &&
> + format != VIR_STORAGE_FILE_QCOW2) {
> + virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
> + _("Cannot pre-create storage of %s format"),
> + virStorageFileFormatTypeToString(format));
> + goto cleanup;
> + }
> +
> + if (!(mig->nbd->disk[mig->nbd->ndisks].target = strdup(disk->dst))) {
> + virReportOOMError();
> + goto cleanup;
> + }
> +
> + mig->nbd->disk[mig->nbd->ndisks].bytes = info.capacity;
> + mig->nbd->ndisks++;
> + }
> }
>
> mig->nbd->port = priv->nbdPort;
> mig->flags |= QEMU_MIGRATION_COOKIE_NBD;
>
> - return 0;
> + ret = 0;
> +
> +cleanup:
> + if (ret < 0)
> + qemuMigrationCookieNBDFree(mig->nbd);
> +
> + return ret;
> }
>
>
...
> @@ -946,20 +1034,56 @@ qemuMigrationCookieXMLParse(qemuMigrationCookiePtr mig,
> virXPathBoolean("boolean(./nbd)", ctxt)) {
> char *port;
>
> + if (VIR_ALLOC(mig->nbd) < 0) {
> + virReportOOMError();
> + goto error;
> + }
> +
> port = virXPathString("string(./nbd/@port)", ctxt);
> - if (port) {
> - if (VIR_ALLOC(mig->nbd) < 0) {
> + if (port && virStrToLong_i(port, NULL, 10, &mig->nbd->port) < 0) {
> + VIR_FREE(port);
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("Malformed nbd port '%s'"),
> + port);
Oops, I believe you wanted to swap these two lines :-)
> + goto error;
> + }
> + VIR_FREE(port);
> +
> + if ((n = virXPathNodeSet("./nbd/disk", ctxt, &nodes)) > 0) {
> + xmlNodePtr oldNode = ctxt->node;
> + if (VIR_ALLOC_N(mig->nbd->disk, n) < 0) {
> virReportOOMError();
> goto error;
> }
> - if (virStrToLong_i(port, NULL, 10, &mig->nbd->port) < 0) {
> - VIR_FREE(port);
> - virReportError(VIR_ERR_INTERNAL_ERROR,
> - _("Malformed nbd port '%s'"),
> - port);
> - goto error;
> + mig->nbd->ndisks = n;
> +
> + for (i = 0; i < n; i++) {
> + ctxt->node = nodes[i];
When accessing just attributes, it's usually easier to just call
virXMLPropString(nodes[i], "name") instead of using XPath machinery.
> +
> + tmp = virXPathString("string(./@target)", ctxt);
> + if (!tmp) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("Malformed target attribute"));
I think this should rather be "Malformed NBD disk target attribute".
> + goto error;
> + }
> + mig->nbd->disk[i].target = tmp;
> + /* deliberately don't free @tmp here, as the
> + * cookie has the reference now and it is
> + * responsible for freeing it later */
> +
> + tmp = virXPathString("string(./@size)", ctxt);
> + if (virStrToLong_ull(tmp, NULL, 10, (unsigned long long *)
> + &mig->nbd->disk[i].bytes) < 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("Malformed size attribute '%s'"),
You should mention NBD disk here as well.
> + tmp);
> + VIR_FREE(tmp);
> + goto error;
> + }
> + VIR_FREE(tmp);
> }
> - VIR_FREE(port);
> + VIR_FREE(nodes);
> + ctxt->node = oldNode;
> }
> }
>
> @@ -1352,6 +1476,152 @@ error:
> goto cleanup;
> }
>
> +static int
> +qemuMigrationPreCreateStorageRaw(virDomainDiskDefPtr disk,
> + size_t bytes)
> +{
> + int ret = -1;
> + struct stat sb;
> + int fd = -1;
> +
> + if ((fd = virFileOpenAs(disk->src, O_RDWR | O_CREAT, 0660,
> + -1, -1, VIR_FILE_OPEN_NOFORK)) < 0) {
> + virReportSystemError(errno, _("Unable to create '%s'"), disk->src);
> + goto cleanup;
> + }
> +
> + if (fstat(fd, &sb) < 0) {
> + virReportSystemError(errno, _("Unable to stat '%s'"), disk->src);
> + goto unlink;
> + }
> +
> + VIR_DEBUG("File '%s' is %zuB big. Required %zuB", disk->src, sb.st_size, bytes);
> + if (sb.st_size < bytes) {
> + if (ftruncate(fd, bytes) < 0) {
> + virReportSystemError(errno, _("Unable to ftruncate '%s'"), disk->src);
> + goto unlink;
> + }
Shouldn't we rather call posix_fallocate or something similar?
> +
> + if (fsync(fd) < 0) {
> + ret = -errno;
No need to pass errno to the caller.
> + virReportSystemError(errno, _("cannot sync data to file '%s'"),
> + disk->src);
> + goto unlink;
> + }
> + }
> +
> + ret = 0;
> +
> +cleanup:
> + VIR_FORCE_CLOSE(fd);
You should really call VIR_CLOSE(fd) here and check for errors.
> + return ret;
> +
> +unlink:
> + if (unlink(disk->src) < 0)
> + VIR_WARN("Unable to unlink '%s': %d", disk->src, errno);
> + goto cleanup;
What if the file was already there but it was just too small and making
it larger failed. I don't think you want to unlink it in this case.
> +}
> +
> +static int
> +qemuMigrationPreCreateStorageQCOW(virQEMUDriverPtr driver,
> + virDomainDiskDefPtr disk,
> + int format,
> + size_t bytes)
> +{
> + int ret = -1;
> + const char *imgBinary = qemuFindQemuImgBinary(driver);
> + virCommandPtr cmd = NULL;
> + size_t size_arg;
> +
> + if (!imgBinary)
> + return ret;
> +
> + /* Size in KB */
> + size_arg = VIR_DIV_UP(bytes, 1024);
> +
> + cmd = virCommandNewArgList(imgBinary, "create", "-f",
> + virStorageFileFormatTypeToString(format),
> + "-o", "preallocation=metadata",
> + disk->src, NULL);
Wrong indentation.
> +
> + virCommandAddArgFormat(cmd, "%zuK", size_arg);
Any particular reason why we need to round up the size when we can just
use bytes?
virCommandAddArgFormat(cmd, "%zu", bytes);
> +
> + if (virCommandRun(cmd, NULL) < 0)
> + goto unlink;
What happens if the QCOW is already there?
> +
> + ret = 0;
> +
> +cleanup:
> + return ret;
> +
> +unlink:
> + if (unlink(disk->src) < 0)
> + VIR_WARN("Unable to unlink '%s': %d", disk->src, errno);
> + goto cleanup;
> +}
Anyway, I feel like all this storage creation code should be placed in a
storage driver somewhere.
> +
> +static int
> +qemuMigrationPreCreateStorage(virQEMUDriverPtr driver,
> + virDomainObjPtr vm,
> + qemuMigrationCookiePtr mig)
> +{
> + int ret = -1;
> + size_t i = 0;
> +
> + if (!mig->nbd || !mig->nbd->ndisks) {
> + /* nothing to do here */
> + return 0;
> + }
> +
> + for (i = 0; i < mig->nbd->ndisks; i++) {
> + virDomainDiskDefPtr disk;
> + int format;
> + size_t bytes;
> + int index;
This fails to compile:
error: declaration of 'index' shadows a global declaration
> +
> + index = virDomainDiskIndexByName(vm->def, mig->nbd->disk[i].target, false);
> + if (index < 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("No such disk '%s"),
> + mig->nbd->disk[i].target);
> + goto cleanup;
> + }
> +
> + disk = vm->def->disks[i];
As John already said, I think you want vm->def->disks[index] here.
> + format = disk->format;
> + bytes = mig->nbd->disk[i].bytes;
> +
> + VIR_DEBUG("Checking '%s' of %s format for its size (requested %zuB)",
> + disk->src, virStorageFileFormatTypeToString(format), bytes);
> + switch (format) {
> + case VIR_STORAGE_FILE_RAW:
> + if (qemuMigrationPreCreateStorageRaw(disk, bytes) < 0)
> + goto cleanup;
> + break;
> + case VIR_STORAGE_FILE_QCOW:
> + case VIR_STORAGE_FILE_QCOW2:
> + if (qemuMigrationPreCreateStorageQCOW(driver, disk,
> + format, bytes) < 0)
> + goto cleanup;
> + break;
> + default:
> + virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
> + _("Cannot pre-create disks of %s format"),
> + virStorageFileFormatTypeToString(format));
> + goto cleanup;
> + }
> +
> + }
> +
> + ret = 0;
> +cleanup:
> + /* free from migration data to prevent
> + * infinite sending from src to dst and back */
> + VIR_FREE(mig->nbd->disk);
This leaks all disk targets.
> + mig->nbd->ndisks = 0;
> + return ret;
> +}
> +
> /* Validate whether the domain is safe to migrate. If vm is NULL,
> * then this is being run in the v2 Prepare stage on the destination
> * (where we only have the target xml); if vm is provided, then this
> @@ -2014,6 +2284,10 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
> QEMU_MIGRATION_COOKIE_NBD)))
> goto cleanup;
>
> + /* pre-create all storage */
> + if (qemuMigrationPreCreateStorage(driver, vm, mig) < 0)
> + goto cleanup;
> +
What happens if the disks we are pre-creating exist and are used by
another domain on the destination host? :-P Normally, migration would
fail if locking manager is in use but with your code, we'd just happily
overwrite all disks, right? :-) I'm afraid we should deal with lock
manager somehow to avoid doing that :-/
> if (qemuMigrationJobStart(driver, vm, QEMU_ASYNC_JOB_MIGRATION_IN) < 0)
> goto cleanup;
> qemuMigrationJobSetPhase(driver, vm, QEMU_MIGRATION_PHASE_PREPARE);
Jirka
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