Re: [libvirt] [PATCH v3 09/12] 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. --- 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 defad6b..d10c5b5 100644 --- a/src/qemu/qemu_migration.c +++ b/src/qemu/qemu_migration.c @@ -29,6 +29,9 @@ #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" @@ -134,6 +137,15 @@ struct _qemuMigrationCookieNBD { int port; /* on which port does NBD server listen for incoming data. Zero value has special meaning - it is there just to let destination know we (the source) do support NBD. */ + + /* 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; @@ -196,6 +208,22 @@ 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) @@ -207,12 +235,14 @@ 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); } @@ -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; + + 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; } @@ -650,7 +729,16 @@ 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"); @@ -942,20 +1030,56 @@ 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); + 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]; + + 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(port); + VIR_FREE(nodes); + ctxt->node = oldNode; } } @@ -1348,6 +1472,152 @@ 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; + } + + if (fsync(fd) < 0) { + ret = -errno; + virReportSystemError(errno, _("cannot sync data to file '%s'"), + disk->src); + goto unlink; + } + } + + ret = 0; + +cleanup: + VIR_FORCE_CLOSE(fd); + return ret; + +unlink: + if (unlink(disk->src) < 0) + VIR_WARN("Unable to unlink '%s': %d", disk->src, errno); + goto cleanup; +} + +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 (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); + 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 @@ -2003,6 +2273,10 @@ 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);