* John Snow (js...@redhat.com) wrote:
> If a migration is already in progress and somebody attempts
> to add a migration blocker, this should rightly fail.
>
> Add an errp parameter and a retcode return value to migrate_add_blocker.
>
> This is part one of two for a solution to prohibit e.g. block jobs
> from running concurrently with migration.
>
> Signed-off-by: John Snow <js...@redhat.com>
For the migration code only:
Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
Dave
> ---
> block/qcow.c | 6 +++++-
> block/vdi.c | 6 +++++-
> block/vhdx.c | 6 +++++-
> block/vmdk.c | 7 ++++++-
> block/vpc.c | 10 +++++++---
> block/vvfat.c | 20 ++++++++++++--------
> hw/9pfs/virtio-9p.c | 16 ++++++++++++----
> hw/misc/ivshmem.c | 5 ++++-
> hw/scsi/vhost-scsi.c | 25 +++++++++++++++++++------
> hw/virtio/vhost.c | 35 +++++++++++++++++++++++------------
> include/migration/migration.h | 6 +++++-
> migration/migration.c | 32 ++++++++++++++++++++++++++++----
> stubs/migr-blocker.c | 3 ++-
> target-i386/kvm.c | 16 +++++++++++++---
> 14 files changed, 146 insertions(+), 47 deletions(-)
>
> diff --git a/block/qcow.c b/block/qcow.c
> index 6e35db1..fbb498f 100644
> --- a/block/qcow.c
> +++ b/block/qcow.c
> @@ -236,7 +236,11 @@ static int qcow_open(BlockDriverState *bs, QDict
> *options, int flags,
> error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
> "does not support live migration",
> bdrv_get_device_or_node_name(bs));
> - migrate_add_blocker(s->migration_blocker);
> + ret = migrate_add_blocker(s->migration_blocker, errp);
> + if (ret < 0) {
> + error_free(s->migration_blocker);
> + goto fail;
> + }
>
> qemu_co_mutex_init(&s->lock);
> return 0;
> diff --git a/block/vdi.c b/block/vdi.c
> index 062a654..1635ab1 100644
> --- a/block/vdi.c
> +++ b/block/vdi.c
> @@ -505,7 +505,11 @@ static int vdi_open(BlockDriverState *bs, QDict
> *options, int flags,
> error_setg(&s->migration_blocker, "The vdi format used by node '%s' "
> "does not support live migration",
> bdrv_get_device_or_node_name(bs));
> - migrate_add_blocker(s->migration_blocker);
> + ret = migrate_add_blocker(s->migration_blocker, errp);
> + if (ret < 0) {
> + error_free(s->migration_blocker);
> + goto fail_free_bmap;
> + }
>
> qemu_co_mutex_init(&s->write_lock);
>
> diff --git a/block/vhdx.c b/block/vhdx.c
> index d3bb1bd..097c707 100644
> --- a/block/vhdx.c
> +++ b/block/vhdx.c
> @@ -1005,7 +1005,11 @@ static int vhdx_open(BlockDriverState *bs, QDict
> *options, int flags,
> error_setg(&s->migration_blocker, "The vhdx format used by node '%s' "
> "does not support live migration",
> bdrv_get_device_or_node_name(bs));
> - migrate_add_blocker(s->migration_blocker);
> + ret = migrate_add_blocker(s->migration_blocker, errp);
> + if (ret < 0) {
> + error_free(s->migration_blocker);
> + goto fail;
> + }
>
> return 0;
> fail:
> diff --git a/block/vmdk.c b/block/vmdk.c
> index be0d640..36ff6f4 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -951,7 +951,12 @@ static int vmdk_open(BlockDriverState *bs, QDict
> *options, int flags,
> error_setg(&s->migration_blocker, "The vmdk format used by node '%s' "
> "does not support live migration",
> bdrv_get_device_or_node_name(bs));
> - migrate_add_blocker(s->migration_blocker);
> + ret = migrate_add_blocker(s->migration_blocker, errp);
> + if (ret < 0) {
> + error_free(s->migration_blocker);
> + goto fail;
> + }
> +
> g_free(buf);
> return 0;
>
> diff --git a/block/vpc.c b/block/vpc.c
> index 2b3b518..f3dd677 100644
> --- a/block/vpc.c
> +++ b/block/vpc.c
> @@ -325,13 +325,17 @@ static int vpc_open(BlockDriverState *bs, QDict
> *options, int flags,
> #endif
> }
>
> - qemu_co_mutex_init(&s->lock);
> -
> /* Disable migration when VHD images are used */
> error_setg(&s->migration_blocker, "The vpc format used by node '%s' "
> "does not support live migration",
> bdrv_get_device_or_node_name(bs));
> - migrate_add_blocker(s->migration_blocker);
> + ret = migrate_add_blocker(s->migration_blocker, errp);
> + if (ret < 0) {
> + error_free(s->migration_blocker);
> + goto fail;
> + }
> +
> + qemu_co_mutex_init(&s->lock);
>
> return 0;
>
> diff --git a/block/vvfat.c b/block/vvfat.c
> index 7ddc962..bdc1297 100644
> --- a/block/vvfat.c
> +++ b/block/vvfat.c
> @@ -1191,22 +1191,26 @@ static int vvfat_open(BlockDriverState *bs, QDict
> *options, int flags,
>
> s->sector_count = s->faked_sectors +
> s->sectors_per_cluster*s->cluster_count;
>
> - if (s->first_sectors_number == 0x40) {
> - init_mbr(s, cyls, heads, secs);
> - }
> -
> - // assert(is_consistent(s));
> - qemu_co_mutex_init(&s->lock);
> -
> /* Disable migration when vvfat is used rw */
> if (s->qcow) {
> error_setg(&s->migration_blocker,
> "The vvfat (rw) format used by node '%s' "
> "does not support live migration",
> bdrv_get_device_or_node_name(bs));
> - migrate_add_blocker(s->migration_blocker);
> + ret = migrate_add_blocker(s->migration_blocker, errp);
> + if (ret < 0) {
> + error_free(s->migration_blocker);
> + goto fail;
> + }
> }
>
> + if (s->first_sectors_number == 0x40) {
> + init_mbr(s, cyls, heads, secs);
> + }
> +
> + // assert(is_consistent(s));
> + qemu_co_mutex_init(&s->lock);
> +
> ret = 0;
> fail:
> qemu_opts_del(opts);
> diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
> index f972731..67dc626 100644
> --- a/hw/9pfs/virtio-9p.c
> +++ b/hw/9pfs/virtio-9p.c
> @@ -978,20 +978,28 @@ static void v9fs_attach(void *opaque)
> clunk_fid(s, fid);
> goto out;
> }
> - err += offset;
> - trace_v9fs_attach_return(pdu->tag, pdu->id,
> - qid.type, qid.version, qid.path);
> +
> /*
> * disable migration if we haven't done already.
> * attach could get called multiple times for the same export.
> */
> if (!s->migration_blocker) {
> + int ret;
> s->root_fid = fid;
> error_setg(&s->migration_blocker,
> "Migration is disabled when VirtFS export path '%s' is
> mounted in the guest using mount_tag '%s'",
> s->ctx.fs_root ? s->ctx.fs_root : "NULL", s->tag);
> - migrate_add_blocker(s->migration_blocker);
> + ret = migrate_add_blocker(s->migration_blocker, NULL);
> + if (ret < 0) {
> + err = ret;
> + clunk_fid(s, fid);
> + goto out;
> + }
> }
> +
> + err += offset;
> + trace_v9fs_attach_return(pdu->tag, pdu->id,
> + qid.type, qid.version, qid.path);
> out:
> put_fid(pdu, fidp);
> out_nofid:
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index cc76989..859e844 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -740,7 +740,10 @@ static int pci_ivshmem_init(PCIDevice *dev)
> if (s->role_val == IVSHMEM_PEER) {
> error_setg(&s->migration_blocker,
> "Migration is disabled when using feature 'peer mode' in
> device 'ivshmem'");
> - migrate_add_blocker(s->migration_blocker);
> + if (migrate_add_blocker(s->migration_blocker, NULL) < 0) {
> + error_report("Unable to prohibit migration during ivshmem init");
> + exit(1);
> + }
> }
>
> pci_conf = dev->config;
> diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
> index fb7983d..46ab197 100644
> --- a/hw/scsi/vhost-scsi.c
> +++ b/hw/scsi/vhost-scsi.c
> @@ -239,8 +239,14 @@ static void vhost_scsi_realize(DeviceState *dev, Error
> **errp)
> vhost_dummy_handle_output);
> if (err != NULL) {
> error_propagate(errp, err);
> - close(vhostfd);
> - return;
> + goto close_fd;
> + }
> +
> + error_setg(&s->migration_blocker,
> + "vhost-scsi does not support migration");
> + ret = migrate_add_blocker(s->migration_blocker, errp);
> + if (ret < 0) {
> + goto free_blocker;
> }
>
> s->dev.nvqs = VHOST_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
> @@ -253,7 +259,7 @@ static void vhost_scsi_realize(DeviceState *dev, Error
> **errp)
> if (ret < 0) {
> error_setg(errp, "vhost-scsi: vhost initialization failed: %s",
> strerror(-ret));
> - return;
> + goto free_vqs;
> }
>
> /* At present, channel and lun both are 0 for bootable vhost-scsi disk */
> @@ -262,9 +268,16 @@ static void vhost_scsi_realize(DeviceState *dev, Error
> **errp)
> /* Note: we can also get the minimum tpgt from kernel */
> s->target = vs->conf.boot_tpgt;
>
> - error_setg(&s->migration_blocker,
> - "vhost-scsi does not support migration");
> - migrate_add_blocker(s->migration_blocker);
> + return;
> +
> + free_vqs:
> + migrate_del_blocker(s->migration_blocker);
> + g_free(s->dev.vqs);
> + free_blocker:
> + error_free(s->migration_blocker);
> + close_fd:
> + close(vhostfd);
> + return;
> }
>
> static void vhost_scsi_unrealize(DeviceState *dev, Error **errp)
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index c0ed5b2..0de7a01 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -926,13 +926,25 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> goto fail;
> }
>
> - for (i = 0; i < hdev->nvqs; ++i) {
> - r = vhost_virtqueue_init(hdev, hdev->vqs + i, hdev->vq_index + i);
> - if (r < 0) {
> - goto fail_vq;
> - }
> - }
> hdev->features = features;
> + hdev->migration_blocker = NULL;
> +
> + if (!(hdev->features & (0x1ULL << VHOST_F_LOG_ALL))) {
> + error_setg(&hdev->migration_blocker,
> + "Migration disabled: vhost lacks VHOST_F_LOG_ALL
> feature.");
> + r = migrate_add_blocker(hdev->migration_blocker, NULL);
> + if (r < 0) {
> + errno = -r;
> + goto fail_mig;
> + }
> + }
> +
> + for (i = 0; i < hdev->nvqs; ++i) {
> + r = vhost_virtqueue_init(hdev, hdev->vqs + i, hdev->vq_index + i);
> + if (r < 0) {
> + goto fail_vq;
> + }
> + }
>
> hdev->memory_listener = (MemoryListener) {
> .begin = vhost_begin,
> @@ -949,12 +961,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> .eventfd_del = vhost_eventfd_del,
> .priority = 10
> };
> - hdev->migration_blocker = NULL;
> - if (!(hdev->features & (0x1ULL << VHOST_F_LOG_ALL))) {
> - error_setg(&hdev->migration_blocker,
> - "Migration disabled: vhost lacks VHOST_F_LOG_ALL
> feature.");
> - migrate_add_blocker(hdev->migration_blocker);
> - }
> +
> hdev->mem = g_malloc0(offsetof(struct vhost_memory, regions));
> hdev->n_mem_sections = 0;
> hdev->mem_sections = NULL;
> @@ -965,10 +972,14 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> hdev->memory_changed = false;
> memory_listener_register(&hdev->memory_listener, &address_space_memory);
> return 0;
> +
> fail_vq:
> while (--i >= 0) {
> vhost_virtqueue_cleanup(hdev->vqs + i);
> }
> + migrate_del_blocker(hdev->migration_blocker);
> +fail_mig:
> + error_free(hdev->migration_blocker);
> fail:
> r = -errno;
> hdev->vhost_ops->vhost_backend_cleanup(hdev);
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index 8334621..fc18956 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -117,6 +117,7 @@ int migrate_fd_close(MigrationState *s);
> void add_migration_state_change_notifier(Notifier *notify);
> void remove_migration_state_change_notifier(Notifier *notify);
> bool migration_in_setup(MigrationState *);
> +bool migration_has_started(MigrationState *s);
> bool migration_has_finished(MigrationState *);
> bool migration_has_failed(MigrationState *);
> MigrationState *migrate_get_current(void);
> @@ -150,8 +151,11 @@ void ram_handle_compressed(void *host, uint8_t ch,
> uint64_t size);
> * @migrate_add_blocker - prevent migration from proceeding
> *
> * @reason - an error to be returned whenever migration is attempted
> + * @errp - [out] The reason (if any) we cannot block migration right now.
> + *
> + * @returns - 0 on success, -EBUSY on failure, with errp set.
> */
> -void migrate_add_blocker(Error *reason);
> +int migrate_add_blocker(Error *reason, Error **errp);
>
> /**
> * @migrate_del_blocker - remove a blocking error from migration
> diff --git a/migration/migration.c b/migration/migration.c
> index e48dd13..897ae40 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -632,6 +632,26 @@ bool migration_has_failed(MigrationState *s)
> s->state == MIGRATION_STATUS_FAILED);
> }
>
> +bool migration_has_started(MigrationState *s)
> +{
> + if (!s) {
> + s = migrate_get_current();
> + }
> +
> + switch (s->state) {
> + case MIGRATION_STATUS_NONE:
> + case MIGRATION_STATUS_CANCELLED:
> + case MIGRATION_STATUS_COMPLETED:
> + case MIGRATION_STATUS_FAILED:
> + return false;
> + case MIGRATION_STATUS_SETUP:
> + case MIGRATION_STATUS_CANCELLING:
> + case MIGRATION_STATUS_ACTIVE:
> + default:
> + return true;
> + }
> +}
> +
> static MigrationState *migrate_init(const MigrationParams *params)
> {
> MigrationState *s = migrate_get_current();
> @@ -667,9 +687,15 @@ static MigrationState *migrate_init(const
> MigrationParams *params)
>
> static GSList *migration_blockers;
>
> -void migrate_add_blocker(Error *reason)
> +int migrate_add_blocker(Error *reason, Error **errp)
> {
> + if (migration_has_started(NULL)) {
> + error_setg(errp, "Cannot block a migration already in-progress");
> + return -EBUSY;
> + }
> +
> migration_blockers = g_slist_prepend(migration_blockers, reason);
> + return 0;
> }
>
> void migrate_del_blocker(Error *reason)
> @@ -712,9 +738,7 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
> params.blk = has_blk && blk;
> params.shared = has_inc && inc;
>
> - if (s->state == MIGRATION_STATUS_ACTIVE ||
> - s->state == MIGRATION_STATUS_SETUP ||
> - s->state == MIGRATION_STATUS_CANCELLING) {
> + if (migration_has_started(s)) {
> error_setg(errp, QERR_MIGRATION_ACTIVE);
> return;
> }
> diff --git a/stubs/migr-blocker.c b/stubs/migr-blocker.c
> index 300df6e..06812bd 100644
> --- a/stubs/migr-blocker.c
> +++ b/stubs/migr-blocker.c
> @@ -1,8 +1,9 @@
> #include "qemu-common.h"
> #include "migration/migration.h"
>
> -void migrate_add_blocker(Error *reason)
> +int migrate_add_blocker(Error *reason, Error **errp)
> {
> + return 0;
> }
>
> void migrate_del_blocker(Error *reason)
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index 7b0ba17..f45baa5 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -731,7 +731,11 @@ int kvm_arch_init_vcpu(CPUState *cs)
> error_setg(&invtsc_mig_blocker,
> "State blocked by non-migratable CPU device"
> " (invtsc flag)");
> - migrate_add_blocker(invtsc_mig_blocker);
> + r = migrate_add_blocker(invtsc_mig_blocker, NULL);
> + if (r < 0) {
> + fprintf(stderr, "migrate_add_blocker failed\n");
> + goto fail_mig;
> + }
> /* for savevm */
> vmstate_x86_cpu.unmigratable = 1;
> }
> @@ -739,7 +743,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
> cpuid_data.cpuid.padding = 0;
> r = kvm_vcpu_ioctl(cs, KVM_SET_CPUID2, &cpuid_data);
> if (r) {
> - return r;
> + goto fail_ioctl;
> }
>
> r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL);
> @@ -747,7 +751,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
> r = kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz);
> if (r < 0) {
> fprintf(stderr, "KVM_SET_TSC_KHZ failed\n");
> - return r;
> + goto fail_ioctl;
> }
> }
>
> @@ -760,6 +764,12 @@ int kvm_arch_init_vcpu(CPUState *cs)
> }
>
> return 0;
> +
> + fail_ioctl:
> + migrate_del_blocker(invtsc_mig_blocker);
> + fail_mig:
> + error_free(invtsc_mig_blocker);
> + return r;
> }
>
> void kvm_arch_reset_vcpu(X86CPU *cpu)
> --
> 2.4.3
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
