block: Remove drained_end_counter

drained_end_counter is unused now, nobody changes its value any more. It
can be removed.

In cases where we had two almost identical functions that only differed
in whether the caller passes drained_end_counter, or whether they would
poll for a local drained_end_counter to reach 0, these become a single
function.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20221118174110.55183-5-kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 1 insertions, 29 deletions

diff --git a/include/block/block-io.h b/include/block/block-io.h
index b099d7db45..054e964c9b 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -237,21 +237,6 @@ int coroutine_fn bdrv_co_copy_range(BdrvChild *src, int64_t src_offset,
                                     int64_t bytes, BdrvRequestFlags read_flags,
                                     BdrvRequestFlags write_flags);
 
-/**
- * bdrv_drained_end_no_poll:
- *
- * Same as bdrv_drained_end(), but do not poll for the subgraph to
- * actually become unquiesced.  Therefore, no graph changes will occur
- * with this function.
- *
- * *drained_end_counter is incremented for every background operation
- * that is scheduled, and will be decremented for every operation once
- * it settles.  The caller must poll until it reaches 0.  The counter
- * should be accessed using atomic operations only.
- */
-void bdrv_drained_end_no_poll(BlockDriverState *bs, int *drained_end_counter);
-
-
 /*
  * "I/O or GS" API functions. These functions can run without
  * the BQL, but only in one specific iothread/main loop.
@@ -311,9 +296,6 @@ void bdrv_parent_drained_begin_single(BdrvChild *c, bool poll);
  * bdrv_parent_drained_end_single:
  *
  * End a quiesced section for the parent of @c.
- *
- * This polls @bs's AioContext until all scheduled sub-drained_ends
- * have settled, which may result in graph changes.
  */
 void bdrv_parent_drained_end_single(BdrvChild *c);
 
@@ -361,12 +343,6 @@ void bdrv_subtree_drained_begin(BlockDriverState *bs);
  * bdrv_drained_end:
  *
  * End a quiescent section started by bdrv_drained_begin().
- *
- * This polls @bs's AioContext until all scheduled sub-drained_ends
- * have settled.  On one hand, that may result in graph changes.  On
- * the other, this requires that the caller either runs in the main
- * loop; or that all involved nodes (@bs and all of its parents) are
- * in the caller's AioContext.
  */
 void bdrv_drained_end(BlockDriverState *bs);
 
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 40d646d1ed..2b97576f6d 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -939,15 +939,11 @@ struct BdrvChildClass {
      * These functions must not change the graph (and therefore also must not
      * call aio_poll(), which could change the graph indirectly).
      *
-     * If drained_end() schedules background operations, it must atomically
-     * increment *drained_end_counter for each such operation and atomically
-     * decrement it once the operation has settled.
-     *
      * Note that this can be nested. If drained_begin() was called twice, new
      * I/O is allowed only after drained_end() was called twice, too.
      */
     void (*drained_begin)(BdrvChild *child);
-    void (*drained_end)(BdrvChild *child, int *drained_end_counter);
+    void (*drained_end)(BdrvChild *child);
 
     /*
      * Returns whether the parent has pending requests for the child. This