Re: [libvirt] [PATCH RESEND 3/4] qemu_migration: Check size prerequisites

With new NBD storage migration approach there are several requirements that need to be meet for successful use of the 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. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_migration.c | 286 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 281 insertions(+), 5 deletions(-) diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c index 69a9013..5080b0a 100644 --- a/src/qemu/qemu_migration.c +++ b/src/qemu/qemu_migration.c @@ -31,6 +31,9 @@ #endif #include <fcntl.h> #include <poll.h> +#include <unistd.h> +#include <sys/types.h> +#include <sys/stat.h> #include "qemu_migration.h" #include "qemu_monitor.h" @@ -135,6 +138,15 @@ typedef struct _qemuMigrationCookieNBD qemuMigrationCookieNBD; typedef qemuMigrationCookieNBD *qemuMigrationCookieNBDPtr; struct _qemuMigrationCookieNBD { int port; /* on which port does NBD server listen for incoming data */ + + /* The list of pairs [disk, size] (in Bytes).

+ * This is needed because the same disk size is one of + * prerequisites for NBD storage migration. */ + size_t ndisks; + struct { + char *target; + size_t bytes; + } *disk; }; typedef struct _qemuMigrationCookie qemuMigrationCookie; @@ -197,6 +209,22 @@ qemuMigrationCookieNetworkFree(qemuMigrationCookieNetworkPtr network) } +static void +qemuMigrationCookieNBDFree(qemuMigrationCookieNBDPtr nbd) +{ + size_t i; + + if (!nbd) + return; + + for (i = 0; i < nbd->ndisks; i++) + VIR_FREE(nbd->disk[i].target); + + VIR_FREE(nbd->disk); + VIR_FREE(nbd); +} + + static void qemuMigrationCookieFree(qemuMigrationCookiePtr mig) { if (!mig) @@ -208,12 +236,14 @@ static void qemuMigrationCookieFree(qemuMigrationCookiePtr mig) if (mig->flags & QEMU_MIGRATION_COOKIE_NETWORK) qemuMigrationCookieNetworkFree(mig->network); + if (mig->flags & QEMU_MIGRATION_COOKIE_NBD) + qemuMigrationCookieNBDFree(mig->nbd); + VIR_FREE(mig->localHostname); VIR_FREE(mig->remoteHostname); VIR_FREE(mig->name); VIR_FREE(mig->lockState); VIR_FREE(mig->lockDriver); - VIR_FREE(mig->nbd); VIR_FREE(mig); } @@ -518,20 +548,58 @@ 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) - 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) + goto cleanup; + + for (i = 0; i < vm->def->ndisks; i++) { + virDomainDiskDefPtr disk = vm->def->disks[i]; + virDomainBlockInfo info; + + /* 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; + + /* Explicitly not checking which formats can be pre-created here, + * as we might be talking to newer libvirt which knows more than we + * do now in here. Just let the destination libvirt decide. */ + if (VIR_STRDUP(mig->nbd->disk[mig->nbd->ndisks].target, disk->dst) < 0) + 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; } @@ -641,7 +709,16 @@ qemuMigrationCookieXMLFormat(virQEMUDriverPtr driver, virBufferAddLit(buf, " <nbd"); if (mig->nbd->port) virBufferAsprintf(buf, " port='%d'", mig->nbd->port); - virBufferAddLit(buf, "/>\n"); + if (mig->nbd->ndisks) { + virBufferAddLit(buf, ">\n"); + for (i = 0; i < mig->nbd->ndisks; i++) + virBufferAsprintf(buf, " <disk target='%s' size='%zu'/>\n", + mig->nbd->disk[i].target, + mig->nbd->disk[i].bytes); + virBufferAddLit(buf, " </nbd>\n"); + } else { + virBufferAddLit(buf, "/>\n"); + } } virBufferAddLit(buf, "</qemu-migration>\n"); @@ -941,6 +1018,44 @@ qemuMigrationCookieXMLParse(qemuMigrationCookiePtr mig, 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; + } + mig->nbd->ndisks = n; + + for (i = 0; i < n; i++) { + ctxt->node = nodes[i]; + + tmp = virXPathString("string(./@target)", ctxt); + if (!tmp) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("Malformed 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'"), + tmp); + VIR_FREE(tmp); + goto error; + } + VIR_FREE(tmp); + } + VIR_FREE(nodes); + ctxt->node = oldNode; + } + VIR_FREE(port);

} virObjectUnref(caps); @@ -1389,6 +1504,163 @@ cleanup: return; } +static int +qemuMigrationPreCreateStorageRaw(virQEMUDriverPtr driver, + virDomainObjPtr vm, + virDomainDiskDefPtr disk, + size_t bytes) +{ + int ret = -1; + struct stat sb; + int fd = -1; + bool need_unlink = false; + + if ((fd = qemuOpenFile(driver, vm, disk->src, O_RDWR | O_CREAT, + &need_unlink, NULL)) < 0) + goto cleanup; + + if (fstat(fd, &sb) < 0) { + virReportSystemError(errno, _("Unable to stat '%s'"), disk->src); + goto cleanup; + } + + VIR_DEBUG("File '%s' is %zuB big. Required %zuB", disk->src, sb.st_size, bytes); + if (sb.st_size != bytes && + posix_fallocate(fd, 0, bytes) < 0) { + virReportSystemError(errno, _("Unable to fallocate '%s'"), disk->src); + goto cleanup; + } + + ret = 0; + +cleanup: + VIR_FORCE_CLOSE(fd); + if (ret < 0 && need_unlink && unlink(disk->src)) + VIR_WARN("Unable to unlink '%s': %d", disk->src, errno); + return ret; +} + +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); + + virCommandAddArgFormat(cmd, "%zuK", size_arg); + + if (virCommandRun(cmd, NULL) < 0) + goto unlink; + + ret = 0; + +cleanup: + return ret; + +unlink: + if (unlink(disk->src) < 0) + VIR_WARN("Unable to unlink '%s': %d", disk->src, errno); + goto cleanup; +} + +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; + + 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]; + 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 ((enum virStorageFileFormat) format) { + /* These below we know how to pre-create. */ + case VIR_STORAGE_FILE_RAW: + if (qemuMigrationPreCreateStorageRaw(driver, vm, 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; + + /* While these we don't know yet. */ + case VIR_STORAGE_FILE_AUTO_SAFE: + case VIR_STORAGE_FILE_AUTO: + case VIR_STORAGE_FILE_NONE: + case VIR_STORAGE_FILE_DIR: + case VIR_STORAGE_FILE_BOCHS: + case VIR_STORAGE_FILE_CLOOP: + case VIR_STORAGE_FILE_COW: + case VIR_STORAGE_FILE_DMG: + case VIR_STORAGE_FILE_ISO: + case VIR_STORAGE_FILE_QED: + case VIR_STORAGE_FILE_VMDK: + case VIR_STORAGE_FILE_VPC: + case VIR_STORAGE_FILE_FAT: + case VIR_STORAGE_FILE_VHD: + case VIR_STORAGE_FILE_VDI: + case VIR_STORAGE_FILE_LAST: + /* Should we error here? As long as user has no control over which + * disks are copied (currently there is no way specifying only a + * set of disks to copy) we can't error here. What we can do is + * leave users with old migration prerequisite: You (users) are + * responsible for creating the storage on the destination. */ + VIR_WARN("Don't know how to pre-create disks of %s type ('%s')", + virStorageFileFormatTypeToString(format), disk->src);

+ break; + } + } + + ret = 0; +cleanup: + /* free from migration data to prevent + * infinite sending from src to dst and back */ + VIR_FREE(mig->nbd->disk);

+ 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 @@ -2305,6 +2577,10 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver, QEMU_MIGRATION_COOKIE_NBD))) goto cleanup; + /* pre-create all storage */ + if (qemuMigrationPreCreateStorage(driver, vm, mig) < 0) + goto cleanup; + if (qemuMigrationJobStart(driver, vm, QEMU_ASYNC_JOB_MIGRATION_IN) < 0) goto cleanup; qemuMigrationJobSetPhase(driver, vm, QEMU_MIGRATION_PHASE_PREPARE); -- 1.8.1.5 -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list