Re: [Qemu-devel] [PATCH V5 1/7] block: Add bs->node_name to hold the name of a bs node of the bs graph.

[Fam Zheng <famz@redhat.com>]

On Thu, 12/12 16:33, Benoît Canet wrote:
> Add the minimum of code to prepare for the following patches.
> 
> Signed-off-by: Benoit Canet <benoit@irqsave.net>
> ---
>  block.c                   | 57 +++++++++++++++++++++++++++++++++++------------
>  include/block/block.h     |  1 +
>  include/block/block_int.h |  9 +++++++-
>  3 files changed, 52 insertions(+), 15 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 64e7d22..481d566 100644
> --- a/block.c
> +++ b/block.c
> @@ -90,6 +90,9 @@ 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);
>  
> @@ -327,7 +330,7 @@ BlockDriverState *bdrv_new(const char *device_name)
>      QLIST_INIT(&bs->dirty_bitmaps);
>      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);
>      }
>      bdrv_iostatus_disable(bs);
>      notifier_list_init(&bs->close_notifiers);
> @@ -1501,7 +1504,7 @@ void bdrv_close_all(void)
>  {
>      BlockDriverState *bs;
>  
> -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> +    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
>          bdrv_close(bs);
>      }
>  }
> @@ -1530,7 +1533,7 @@ 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;
>          }
> @@ -1557,7 +1560,7 @@ void bdrv_drain_all(void)
>      BlockDriverState *bs;
>  
>      while (busy) {
> -        QTAILQ_FOREACH(bs, &bdrv_states, list) {
> +        QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
>              bdrv_start_throttled_reqs(bs);
>          }
>  
> @@ -1566,14 +1569,19 @@ void bdrv_drain_all(void)
>      }
>  }
>  
> -/* make a BlockDriverState anonymous by removing from bdrv_state list.
> +/* make a BlockDriverState anonymous by removing from bdrv_state and
> + * graph_bdrv_state list.
>     Also, NULL terminate the device_name to prevent double remove */
>  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';
> +    if (bs->node_name[0] != '\0') {
> +        QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
> +    }
> +    bs->node_name[0] = '\0';
>  }
>  
>  static void bdrv_rebind(BlockDriverState *bs)
> @@ -1627,7 +1635,12 @@ 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
> +     * We do want to swap name but don't want to swap linked list entries
> +     */
> +    bs_dest->node_list   = bs_src->node_list;
>  }
>  
>  /*
> @@ -1952,7 +1965,7 @@ 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) {
> @@ -3110,11 +3123,12 @@ 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;
>          }
> @@ -3122,19 +3136,34 @@ 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;
> +
> +    assert(node_name);
> +
> +    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);
>      }
>  }
> @@ -3154,7 +3183,7 @@ 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;
> @@ -4278,7 +4307,7 @@ 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);
>      }
>  }
> @@ -4287,7 +4316,7 @@ 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);
>      }
>  }
> diff --git a/include/block/block.h b/include/block/block.h
> index 36efaea..834abf9 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -374,6 +374,7 @@ 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 8b132d7..bd5220f 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -325,11 +325,18 @@ struct BlockDriverState {
>      BlockdevOnError on_read_error, on_write_error;
>      bool iostatus_enabled;
>      BlockDeviceIoStatus iostatus;
> +
> +    /* the following member gives a name to every node on the bs graph. */
> +    char node_name[32];
> +    /* element of the list of named nodes building the graph */
> +    QTAILQ_ENTRY(BlockDriverState) node_list;
> +    /* Device name is the name associated with the "drive" the guest sees */
>      char device_name[32];
> +    /* element of the list of "drives" the guest sees */
> +    QTAILQ_ENTRY(BlockDriverState) device_list;
>      QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
>      int refcnt;
>      int in_use; /* users other than guest access, eg. block migration */
> -    QTAILQ_ENTRY(BlockDriverState) list;
>  
>      QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
>  
> -- 
> 1.8.3.2
> 
> 
Reviewed-by: Fam Zheng <famz@redhat.com>