Re: [Qemu-devel] [PATCH 1/2] block: Add bs->node_name to hold the name of a bs node of the bs graph.

["Benoît Canet" <benoit.canet@irqsave.net>]

Le Thursday 07 Nov 2013 à 15:54:09 (-0500), Jeff Cody a écrit :
> On Thu, Nov 07, 2013 at 04:01:42PM +0100, Benoît Canet wrote:
> > Add the minimum of code to prepare the followings patches.
> > 
> > If no node_name is provided to bdrv_new the bs->node_name is set to "undefined".
> > This will allow to have some default string to communicate in QMP and HMP.
> > This also make "undefined" a reserved string for bs->node_name.
> 
> Hi Benoît,
> 
> Is it necessary to have a reserved string, or would an empty
> null-terminated string be able to implicitly denote the name as
> undefined?

This would works too and just report the "undefined" logic to hmp printing code.
I'll do this.

> 
> > 
> > Signed-off-by: Benoit Canet <benoit@irqsave.net>
> > ---
> >  block.c                   | 70 +++++++++++++++++++++++++++++++++++------------
> >  block/blkverify.c         |  2 +-
> >  block/iscsi.c             |  2 +-
> >  block/vmdk.c              |  2 +-
> >  block/vvfat.c             |  4 +--
> >  blockdev.c                |  8 +++---
> >  hw/block/xen_disk.c       |  2 +-
> >  include/block/block.h     |  3 +-
> >  include/block/block_int.h |  9 +++++-
> >  qemu-img.c                |  6 ++--
> >  qemu-io.c                 |  2 +-
> >  qemu-nbd.c                |  2 +-
> >  12 files changed, 77 insertions(+), 35 deletions(-)
> > 
> > diff --git a/block.c b/block.c
> > index fd05a80..230e71a 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -89,6 +89,9 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
> >  static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
> >      QTAILQ_HEAD_INITIALIZER(bdrv_states);
> >  
> > +static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
> > +    QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
> > +
> >  static QLIST_HEAD(, BlockDriver) bdrv_drivers =
> >      QLIST_HEAD_INITIALIZER(bdrv_drivers);
> >  
> > @@ -318,14 +321,26 @@ void bdrv_register(BlockDriver *bdrv)
> >  }
> >  
> >  /* create a new block device (by default it is empty) */
> > -BlockDriverState *bdrv_new(const char *device_name)
> > +BlockDriverState *bdrv_new(const char *device_name, const char *node_name)
> >  {
> >      BlockDriverState *bs;
> >  
> >      bs = g_malloc0(sizeof(BlockDriverState));
> >      pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);
> >      if (device_name[0] != '\0') {
> > -        QTAILQ_INSERT_TAIL(&bdrv_states, bs, list);
> > +        QTAILQ_INSERT_TAIL(&bdrv_states, bs, device_list);
> > +    }
> > +    /* if node name is given store it in bs and insert bs in the graph bs list
> > +     * note: undefined is a reserved node name
> > +     */
> > +    if (node_name &&
> > +        node_name[0] != '\0' &&
> > +        strcmp(node_name, "undefined")) {
> > +        pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
> > +        QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
> > +    /* else set the bs node name to undefined for QMP and HMP */
> > +    } else {
> > +        sprintf(bs->node_name, "undefined");
> >      }
> >      bdrv_iostatus_disable(bs);
> >      notifier_list_init(&bs->close_notifiers);
> > @@ -870,7 +885,7 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
> >          options = qdict_new();
> >      }
> >  
> > -    bs = bdrv_new("");
> > +    bs = bdrv_new("", NULL);
> >      bs->options = options;
> >      options = qdict_clone_shallow(options);
> >  
> > @@ -992,7 +1007,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
> >                                         sizeof(backing_filename));
> >      }
> >  
> > -    bs->backing_hd = bdrv_new("");
> > +    bs->backing_hd = bdrv_new("", NULL);
> >  
> >      if (bs->backing_format[0] != '\0') {
> >          back_drv = bdrv_find_format(bs->backing_format);
> > @@ -1062,7 +1077,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
> >             instead of opening 'filename' directly */
> >  
> >          /* if there is a backing file, use it */
> > -        bs1 = bdrv_new("");
> > +        bs1 = bdrv_new("", NULL);
> >          ret = bdrv_open(bs1, filename, NULL, 0, drv, &local_err);
> >          if (ret < 0) {
> >              bdrv_unref(bs1);
> > @@ -1495,7 +1510,7 @@ void bdrv_close_all(void)
> >  {
> >      BlockDriverState *bs;
> >  
> > -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >          bdrv_close(bs);
> >      }
> >  }
> > @@ -1524,7 +1539,7 @@ static bool bdrv_requests_pending(BlockDriverState *bs)
> >  static bool bdrv_requests_pending_all(void)
> >  {
> >      BlockDriverState *bs;
> > -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >          if (bdrv_requests_pending(bs)) {
> >              return true;
> >          }
> > @@ -1554,7 +1569,7 @@ void bdrv_drain_all(void)
> >          /* FIXME: We do not have timer support here, so this is effectively
> >           * a busy wait.
> >           */
> > -        QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +        QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >              if (bdrv_start_throttled_reqs(bs)) {
> >                  busy = true;
> >              }
> > @@ -1570,7 +1585,7 @@ void bdrv_drain_all(void)
> >  void bdrv_make_anon(BlockDriverState *bs)
> >  {
> >      if (bs->device_name[0] != '\0') {
> > -        QTAILQ_REMOVE(&bdrv_states, bs, list);
> > +        QTAILQ_REMOVE(&bdrv_states, bs, device_list);
> >      }
> >      bs->device_name[0] = '\0';
> 
> Do you need to do anything here to remove the BDS from your graph list?
> e.g. QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list)

Right.

> 
> >  }
> > @@ -1626,7 +1641,12 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
> >      /* keep the same entry in bdrv_states */
> >      pstrcpy(bs_dest->device_name, sizeof(bs_dest->device_name),
> >              bs_src->device_name);
> > -    bs_dest->list = bs_src->list;
> > +    bs_dest->device_list = bs_src->device_list;
> > +
> > +    /* keep the same entry in graph_bdrv_states */
> > +    pstrcpy(bs_dest->node_name, sizeof(bs_dest->node_name),
> > +            bs_src->node_name);
> > +    bs_dest->node_list   = bs_src->node_list;
> >  }
> >  
> >  /*
> > @@ -1950,7 +1970,7 @@ int bdrv_commit_all(void)
> >  {
> >      BlockDriverState *bs;
> >  
> > -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >          if (bs->drv && bs->backing_hd) {
> >              int ret = bdrv_commit(bs);
> >              if (ret < 0) {
> > @@ -3017,11 +3037,12 @@ void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
> >      }
> >  }
> >  
> > +/* This function is to find block backend bs */
> >  BlockDriverState *bdrv_find(const char *name)
> >  {
> >      BlockDriverState *bs;
> >  
> > -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >          if (!strcmp(name, bs->device_name)) {
> >              return bs;
> >          }
> > @@ -3029,19 +3050,32 @@ BlockDriverState *bdrv_find(const char *name)
> >      return NULL;
> >  }
> >  
> > +/* This function is to find a node in the bs graph */
> > +BlockDriverState *bdrv_find_node(const char *node_name)
> > +{
> > +    BlockDriverState *bs;
> > +
> > +    QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
> > +        if (!strcmp(node_name, bs->node_name)) {
> > +            return bs;
> > +        }
> > +    }
> > +    return NULL;
> > +}
> > +
> >  BlockDriverState *bdrv_next(BlockDriverState *bs)
> >  {
> >      if (!bs) {
> >          return QTAILQ_FIRST(&bdrv_states);
> >      }
> > -    return QTAILQ_NEXT(bs, list);
> > +    return QTAILQ_NEXT(bs, device_list);
> >  }
> >  
> >  void bdrv_iterate(void (*it)(void *opaque, BlockDriverState *bs), void *opaque)
> >  {
> >      BlockDriverState *bs;
> >  
> > -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >          it(opaque, bs);
> >      }
> >  }
> > @@ -3061,7 +3095,7 @@ int bdrv_flush_all(void)
> >      BlockDriverState *bs;
> >      int result = 0;
> >  
> > -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >          int ret = bdrv_flush(bs);
> >          if (ret < 0 && !result) {
> >              result = ret;
> > @@ -4127,7 +4161,7 @@ void bdrv_invalidate_cache_all(void)
> >  {
> >      BlockDriverState *bs;
> >  
> > -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >          bdrv_invalidate_cache(bs);
> >      }
> >  }
> > @@ -4136,7 +4170,7 @@ void bdrv_clear_incoming_migration_all(void)
> >  {
> >      BlockDriverState *bs;
> >  
> > -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
> >          bs->open_flags = bs->open_flags & ~(BDRV_O_INCOMING);
> >      }
> >  }
> > @@ -4582,7 +4616,7 @@ void bdrv_img_create(const char *filename, const char *fmt,
> >              back_flags =
> >                  flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
> >  
> > -            bs = bdrv_new("");
> > +            bs = bdrv_new("", NULL);
> >  
> >              ret = bdrv_open(bs, backing_file->value.s, NULL, back_flags,
> >                              backing_drv, &local_err);
> > diff --git a/block/blkverify.c b/block/blkverify.c
> > index 55819a0..674b6a5 100644
> > --- a/block/blkverify.c
> > +++ b/block/blkverify.c
> > @@ -155,7 +155,7 @@ static int blkverify_open(BlockDriverState *bs, QDict *options, int flags,
> >          goto fail;
> >      }
> >  
> > -    s->test_file = bdrv_new("");
> > +    s->test_file = bdrv_new("", NULL);
> >      ret = bdrv_open(s->test_file, filename, NULL, flags, NULL, &local_err);
> >      if (ret < 0) {
> >          error_propagate(errp, local_err);
> > diff --git a/block/iscsi.c b/block/iscsi.c
> > index a2a961e..5031593 100644
> > --- a/block/iscsi.c
> > +++ b/block/iscsi.c
> > @@ -1461,7 +1461,7 @@ static int iscsi_create(const char *filename, QEMUOptionParameter *options,
> >      IscsiLun *iscsilun = NULL;
> >      QDict *bs_options;
> >  
> > -    bs = bdrv_new("");
> > +    bs = bdrv_new("", NULL);
> >  
> >      /* Read out options */
> >      while (options && options->name) {
> > diff --git a/block/vmdk.c b/block/vmdk.c
> > index 32ec8b77..97801c2 100644
> > --- a/block/vmdk.c
> > +++ b/block/vmdk.c
> > @@ -1672,7 +1672,7 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
> >          return -ENOTSUP;
> >      }
> >      if (backing_file) {
> > -        BlockDriverState *bs = bdrv_new("");
> > +        BlockDriverState *bs = bdrv_new("", NULL);
> >          ret = bdrv_open(bs, backing_file, NULL, 0, NULL, errp);
> >          if (ret != 0) {
> >              bdrv_unref(bs);
> > diff --git a/block/vvfat.c b/block/vvfat.c
> > index 3ddaa0b..a8b6011 100644
> > --- a/block/vvfat.c
> > +++ b/block/vvfat.c
> > @@ -2935,7 +2935,7 @@ static int enable_write_target(BDRVVVFATState *s)
> >          goto err;
> >      }
> >  
> > -    s->qcow = bdrv_new("");
> > +    s->qcow = bdrv_new("", NULL);
> >  
> >      ret = bdrv_open(s->qcow, s->qcow_filename, NULL,
> >              BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH, bdrv_qcow,
> > @@ -2951,7 +2951,7 @@ static int enable_write_target(BDRVVVFATState *s)
> >      unlink(s->qcow_filename);
> >  #endif
> >  
> > -    s->bs->backing_hd = bdrv_new("");
> > +    s->bs->backing_hd = bdrv_new("", NULL);
> >      s->bs->backing_hd->drv = &vvfat_write_target;
> >      s->bs->backing_hd->opaque = g_malloc(sizeof(void*));
> >      *(void**)s->bs->backing_hd->opaque = s;
> > diff --git a/blockdev.c b/blockdev.c
> > index b260477..ac47413 100644
> > --- a/blockdev.c
> > +++ b/blockdev.c
> > @@ -469,7 +469,7 @@ static DriveInfo *blockdev_init(QDict *bs_opts,
> >      /* init */
> >      dinfo = g_malloc0(sizeof(*dinfo));
> >      dinfo->id = g_strdup(qemu_opts_id(opts));
> > -    dinfo->bdrv = bdrv_new(dinfo->id);
> > +    dinfo->bdrv = bdrv_new(dinfo->id, NULL);
> >      dinfo->bdrv->open_flags = snapshot ? BDRV_O_SNAPSHOT : 0;
> >      dinfo->bdrv->read_only = ro;
> >      dinfo->type = type;
> > @@ -1254,7 +1254,7 @@ static void external_snapshot_prepare(BlkTransactionState *common,
> >      }
> >  
> >      /* We will manually add the backing_hd field to the bs later */
> > -    state->new_bs = bdrv_new("");
> > +    state->new_bs = bdrv_new("", NULL);
> >      /* TODO Inherit bs->options or only take explicit options with an
> >       * extended QMP command? */
> >      ret = bdrv_open(state->new_bs, new_image_file, NULL,
> > @@ -1921,7 +1921,7 @@ void qmp_drive_backup(const char *device, const char *target,
> >          return;
> >      }
> >  
> > -    target_bs = bdrv_new("");
> > +    target_bs = bdrv_new("", NULL);
> >      ret = bdrv_open(target_bs, target, NULL, flags, drv, &local_err);
> >      if (ret < 0) {
> >          bdrv_unref(target_bs);
> > @@ -2055,7 +2055,7 @@ void qmp_drive_mirror(const char *device, const char *target,
> >      /* Mirroring takes care of copy-on-write using the source's backing
> >       * file.
> >       */
> > -    target_bs = bdrv_new("");
> > +    target_bs = bdrv_new("", NULL);
> >      ret = bdrv_open(target_bs, target, NULL, flags | BDRV_O_NO_BACKING, drv,
> >                      &local_err);
> >      if (ret < 0) {
> > diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
> > index 098f6c6..d89e025 100644
> > --- a/hw/block/xen_disk.c
> > +++ b/hw/block/xen_disk.c
> > @@ -808,7 +808,7 @@ static int blk_connect(struct XenDevice *xendev)
> >      if (!blkdev->dinfo) {
> >          /* setup via xenbus -> create new block driver instance */
> >          xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
> > -        blkdev->bs = bdrv_new(blkdev->dev);
> > +        blkdev->bs = bdrv_new(blkdev->dev, NULL);
> >          if (blkdev->bs) {
> >              Error *local_err = NULL;
> >              BlockDriver *drv = bdrv_find_whitelisted_format(blkdev->fileproto,
> > diff --git a/include/block/block.h b/include/block/block.h
> > index 3560deb..2d27bd9 100644
> > --- a/include/block/block.h
> > +++ b/include/block/block.h
> > @@ -149,7 +149,7 @@ int bdrv_create(BlockDriver *drv, const char* filename,
> >      QEMUOptionParameter *options, Error **errp);
> >  int bdrv_create_file(const char* filename, QEMUOptionParameter *options,
> >                       Error **errp);
> > -BlockDriverState *bdrv_new(const char *device_name);
> > +BlockDriverState *bdrv_new(const char *device_name, const char *node_name);
> >  void bdrv_make_anon(BlockDriverState *bs);
> >  void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old);
> >  void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top);
> > @@ -339,6 +339,7 @@ void bdrv_lock_medium(BlockDriverState *bs, bool locked);
> >  void bdrv_eject(BlockDriverState *bs, bool eject_flag);
> >  const char *bdrv_get_format_name(BlockDriverState *bs);
> >  BlockDriverState *bdrv_find(const char *name);
> > +BlockDriverState *bdrv_find_node(const char *node_name);
> >  BlockDriverState *bdrv_next(BlockDriverState *bs);
> >  void bdrv_iterate(void (*it)(void *opaque, BlockDriverState *bs),
> >                    void *opaque);
> > diff --git a/include/block/block_int.h b/include/block/block_int.h
> > index a48731d..9e44136 100644
> > --- a/include/block/block_int.h
> > +++ b/include/block/block_int.h
> > @@ -297,11 +297,18 @@ struct BlockDriverState {
> >      BlockdevOnError on_read_error, on_write_error;
> >      bool iostatus_enabled;
> >      BlockDeviceIoStatus iostatus;
> > +
> > +    /* the following member give a name to every node on the BlockDriverState
> > +     * graph.
> > +     */
> > +    char node_name[32];
> > +    QTAILQ_ENTRY(BlockDriverState) node_list;
> > +    /* Device name is the name associated with the "drive" the guest see */
> >      char device_name[32];
> > +    QTAILQ_ENTRY(BlockDriverState) device_list;
> >      HBitmap *dirty_bitmap;
> >      int refcnt;
> >      int in_use; /* users other than guest access, eg. block migration */
> > -    QTAILQ_ENTRY(BlockDriverState) list;
> >  
> >      QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
> >  
> > diff --git a/qemu-img.c b/qemu-img.c
> > index 926f0a0..215b7b2 100644
> > --- a/qemu-img.c
> > +++ b/qemu-img.c
> > @@ -269,7 +269,7 @@ static BlockDriverState *bdrv_new_open(const char *filename,
> >      Error *local_err = NULL;
> >      int ret;
> >  
> > -    bs = bdrv_new("image");
> > +    bs = bdrv_new("image", NULL);
> >  
> >      if (fmt) {
> >          drv = bdrv_find_format(fmt);
> > @@ -2225,7 +2225,7 @@ static int img_rebase(int argc, char **argv)
> >      } else {
> >          char backing_name[1024];
> >  
> > -        bs_old_backing = bdrv_new("old_backing");
> > +        bs_old_backing = bdrv_new("old_backing", NULL);
> >          bdrv_get_backing_filename(bs, backing_name, sizeof(backing_name));
> >          ret = bdrv_open(bs_old_backing, backing_name, NULL, BDRV_O_FLAGS,
> >                          old_backing_drv, &local_err);
> > @@ -2236,7 +2236,7 @@ static int img_rebase(int argc, char **argv)
> >              goto out;
> >          }
> >          if (out_baseimg[0]) {
> > -            bs_new_backing = bdrv_new("new_backing");
> > +            bs_new_backing = bdrv_new("new_backing", NULL);
> >              ret = bdrv_open(bs_new_backing, out_baseimg, NULL, BDRV_O_FLAGS,
> >                          new_backing_drv, &local_err);
> >              if (ret) {
> > diff --git a/qemu-io.c b/qemu-io.c
> > index 3b3340a..3e1ea88 100644
> > --- a/qemu-io.c
> > +++ b/qemu-io.c
> > @@ -63,7 +63,7 @@ static int openfile(char *name, int flags, int growable, QDict *opts)
> >              return 1;
> >          }
> >      } else {
> > -        qemuio_bs = bdrv_new("hda");
> > +        qemuio_bs = bdrv_new("hda", NULL);
> >  
> >          if (bdrv_open(qemuio_bs, name, opts, flags, NULL, &local_err) < 0) {
> >              fprintf(stderr, "%s: can't open device %s: %s\n", progname, name,
> > diff --git a/qemu-nbd.c b/qemu-nbd.c
> > index c26c98e..35ef57c 100644
> > --- a/qemu-nbd.c
> > +++ b/qemu-nbd.c
> > @@ -572,7 +572,7 @@ int main(int argc, char **argv)
> >          drv = NULL;
> >      }
> >  
> > -    bs = bdrv_new("hda");
> > +    bs = bdrv_new("hda", NULL);
> >      srcpath = argv[optind];
> >      ret = bdrv_open(bs, srcpath, NULL, flags, drv, &local_err);
> >      if (ret < 0) {
> > -- 
> > 1.8.3.2
> > 
> > 
>