From 77a02621812952acfde887244f6f480de1b51f95 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Sun, 4 Dec 2011 22:35:28 +0530 Subject: [PATCH 04/25] hw/9pfs: use migration blockers to prevent live migration when virtfs export path is mounted Now when you try to migrate with VirtFS export path mounted, you get a proper QMP error: (qemu) migrate tcp:localhost:4444 Migration is disabled when VirtFS export path '/tmp/' is mounted in the guest using mount_tag 'v_tmp' (qemu) Signed-off-by: Aneesh Kumar K.V --- hw/9pfs/virtio-9p-device.c | 22 +++++++++++----------- hw/9pfs/virtio-9p.c | 19 +++++++++++++++++++ hw/9pfs/virtio-9p.h | 5 +++-- qerror.c | 5 +++++ qerror.h | 3 +++ 5 files changed, 41 insertions(+), 13 deletions(-) diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c index bba4c54..c9bca8b 100644 --- a/hw/9pfs/virtio-9p-device.c +++ b/hw/9pfs/virtio-9p-device.c @@ -33,13 +33,15 @@ static V9fsState *to_virtio_9p(VirtIODevice *vdev) static void virtio_9p_get_config(VirtIODevice *vdev, uint8_t *config) { + int len; struct virtio_9p_config *cfg; V9fsState *s = to_virtio_9p(vdev); - cfg = g_malloc0(sizeof(struct virtio_9p_config) + - s->tag_len); - stw_raw(&cfg->tag_len, s->tag_len); - memcpy(cfg->tag, s->tag, s->tag_len); + len = strlen(s->tag); + cfg = g_malloc0(sizeof(struct virtio_9p_config) + len); + stw_raw(&cfg->tag_len, len); + /* We don't copy the terminating null to config space */ + memcpy(cfg->tag, s->tag, len); memcpy(config, cfg, s->config_size); g_free(cfg); } @@ -96,20 +98,18 @@ VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf) } len = strlen(conf->tag); - if (len > MAX_TAG_LEN) { + if (len > MAX_TAG_LEN - 1) { fprintf(stderr, "mount tag '%s' (%d bytes) is longer than " - "maximum (%d bytes)", conf->tag, len, MAX_TAG_LEN); + "maximum (%d bytes)", conf->tag, len, MAX_TAG_LEN - 1); exit(1); } - /* s->tag is non-NULL terminated string */ - s->tag = g_malloc(len); - memcpy(s->tag, conf->tag, len); - s->tag_len = len; + + s->tag = strdup(conf->tag); s->ctx.uid = -1; s->ops = fse->ops; s->vdev.get_features = virtio_9p_get_features; - s->config_size = sizeof(struct virtio_9p_config) + s->tag_len; + s->config_size = sizeof(struct virtio_9p_config) + len; s->vdev.get_config = virtio_9p_get_config; s->fid_list = NULL; qemu_co_rwlock_init(&s->rename_lock); diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c index 1b2fc5d..32b98dd 100644 --- a/hw/9pfs/virtio-9p.c +++ b/hw/9pfs/virtio-9p.c @@ -23,6 +23,7 @@ #include "virtio-9p-xattr.h" #include "virtio-9p-coth.h" #include "trace.h" +#include "migration.h" int open_fd_hw; int total_open_fd; @@ -373,6 +374,19 @@ static void put_fid(V9fsPDU *pdu, V9fsFidState *fidp) * Don't free the fid if it is in reclaim list */ if (!fidp->ref && fidp->clunked) { + if (fidp->fid == pdu->s->root_fid) { + /* + * if the clunked fid is root fid then we + * have unmounted the fs on the client side. + * delete the migration blocker. Ideally, this + * should be hooked to transport close notification + */ + if (pdu->s->migration_blocker) { + migrate_del_blocker(pdu->s->migration_blocker); + error_free(pdu->s->migration_blocker); + pdu->s->migration_blocker = NULL; + } + } free_fid(pdu, fidp); } } @@ -1235,6 +1249,11 @@ static void v9fs_attach(void *opaque) err = offset; trace_v9fs_attach_return(pdu->tag, pdu->id, qid.type, qid.version, qid.path); + s->root_fid = fid; + /* disable migration */ + error_set(&s->migration_blocker, QERR_VIRTFS_FEATURE_BLOCKS_MIGRATION, + s->ctx.fs_root, s->tag); + migrate_add_blocker(s->migration_blocker); out: put_fid(pdu, fidp); out_nofid: diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h index 7f88356..8b612da 100644 --- a/hw/9pfs/virtio-9p.h +++ b/hw/9pfs/virtio-9p.h @@ -246,8 +246,7 @@ typedef struct V9fsState V9fsFidState *fid_list; FileOperations *ops; FsContext ctx; - uint16_t tag_len; - uint8_t *tag; + char *tag; size_t config_size; enum p9_proto_version proto_version; int32_t msize; @@ -256,6 +255,8 @@ typedef struct V9fsState * on rename. */ CoRwlock rename_lock; + int32_t root_fid; + Error *migration_blocker; } V9fsState; typedef struct V9fsStatState { diff --git a/qerror.c b/qerror.c index fdf62b9..25bc91e 100644 --- a/qerror.c +++ b/qerror.c @@ -235,6 +235,11 @@ static const QErrorStringTable qerror_table[] = { "supported by this qemu version: %(feature)", }, { + .error_fmt = QERR_VIRTFS_FEATURE_BLOCKS_MIGRATION, + .desc = "Migration is disabled when VirtFS export path '%(path)' " + "is mounted in the guest using mount_tag '%(tag)'", + }, + { .error_fmt = QERR_VNC_SERVER_FAILED, .desc = "Could not start VNC server on %(target)", }, diff --git a/qerror.h b/qerror.h index 2d3d43b..6414cd9 100644 --- a/qerror.h +++ b/qerror.h @@ -192,6 +192,9 @@ QError *qobject_to_qerror(const QObject *obj); #define QERR_UNKNOWN_BLOCK_FORMAT_FEATURE \ "{ 'class': 'UnknownBlockFormatFeature', 'data': { 'device': %s, 'format': %s, 'feature': %s } }" +#define QERR_VIRTFS_FEATURE_BLOCKS_MIGRATION \ + "{ 'class': 'VirtFSFeatureBlocksMigration', 'data': { 'path': %s, 'tag': %s } }" + #define QERR_VNC_SERVER_FAILED \ "{ 'class': 'VNCServerFailed', 'data': { 'target': %s } }" -- 1.7.7.5