Merge remote-tracking branch 'remotes/xanclic/tags/pull-block-2018-09-25' into staging

Block layer patches:
- Drain fixes
- node-name parameters for block-commit
- Refactor block jobs to use transactional callbacks for exiting

# gpg: Signature made Tue 25 Sep 2018 16:12:44 BST
# gpg:                using RSA key F407DB0061D5CF40
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>"
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* remotes/xanclic/tags/pull-block-2018-09-25: (42 commits)
  test-bdrv-drain: Test draining job source child and parent
  block: Use a single global AioWait
  test-bdrv-drain: Fix outdated comments
  test-bdrv-drain: AIO_WAIT_WHILE() in job .commit/.abort
  job: Avoid deadlocks in job_completed_txn_abort()
  test-bdrv-drain: Test nested poll in bdrv_drain_poll_top_level()
  block: Remove aio_poll() in bdrv_drain_poll variants
  blockjob: Lie better in child_job_drained_poll()
  block-backend: Decrease in_flight only after callback
  block-backend: Fix potential double blk_delete()
  block-backend: Add .drained_poll callback
  block: Add missing locking in bdrv_co_drain_bh_cb()
  test-bdrv-drain: Test AIO_WAIT_WHILE() in completion callback
  job: Use AIO_WAIT_WHILE() in job_finish_sync()
  test-blockjob: Acquire AioContext around job_cancel_sync()
  test-bdrv-drain: Drain with block jobs in an I/O thread
  aio-wait: Increase num_waiters even in home thread
  blockjob: Wake up BDS when job becomes idle
  job: Fix missing locking due to mismerge
  job: Fix nested aio_poll() hanging in job_txn_apply
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 22 insertions, 9 deletions

diff --git a/block/block-backend.c b/block/block-backend.c
index 14a1b7ac6a..7b1ec5071b 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -88,7 +88,6 @@ struct BlockBackend {
      * Accessed with atomic ops.
      */
     unsigned int in_flight;
-    AioWait wait;
 };
 
 typedef struct BlockBackendAIOCB {
@@ -121,6 +120,7 @@ static void blk_root_inherit_options(int *child_flags, QDict *child_options,
     abort();
 }
 static void blk_root_drained_begin(BdrvChild *child);
+static bool blk_root_drained_poll(BdrvChild *child);
 static void blk_root_drained_end(BdrvChild *child);
 
 static void blk_root_change_media(BdrvChild *child, bool load);
@@ -294,6 +294,7 @@ static const BdrvChildRole child_root = {
     .get_parent_desc    = blk_root_get_parent_desc,
 
     .drained_begin      = blk_root_drained_begin,
+    .drained_poll       = blk_root_drained_poll,
     .drained_end        = blk_root_drained_end,
 
     .activate           = blk_root_activate,
@@ -433,6 +434,7 @@ int blk_get_refcnt(BlockBackend *blk)
  */
 void blk_ref(BlockBackend *blk)
 {
+    assert(blk->refcnt > 0);
     blk->refcnt++;
 }
 
@@ -445,7 +447,13 @@ void blk_unref(BlockBackend *blk)
 {
     if (blk) {
         assert(blk->refcnt > 0);
-        if (!--blk->refcnt) {
+        if (blk->refcnt > 1) {
+            blk->refcnt--;
+        } else {
+            blk_drain(blk);
+            /* blk_drain() cannot resurrect blk, nobody held a reference */
+            assert(blk->refcnt == 1);
+            blk->refcnt = 0;
             blk_delete(blk);
         }
     }
@@ -1289,7 +1297,7 @@ static void blk_inc_in_flight(BlockBackend *blk)
 static void blk_dec_in_flight(BlockBackend *blk)
 {
     atomic_dec(&blk->in_flight);
-    aio_wait_kick(&blk->wait);
+    aio_wait_kick();
 }
 
 static void error_callback_bh(void *opaque)
@@ -1330,8 +1338,8 @@ static const AIOCBInfo blk_aio_em_aiocb_info = {
 static void blk_aio_complete(BlkAioEmAIOCB *acb)
 {
     if (acb->has_returned) {
-        blk_dec_in_flight(acb->rwco.blk);
         acb->common.cb(acb->common.opaque, acb->rwco.ret);
+        blk_dec_in_flight(acb->rwco.blk);
         qemu_aio_unref(acb);
     }
 }
@@ -1590,9 +1598,8 @@ void blk_drain(BlockBackend *blk)
     }
 
     /* We may have -ENOMEDIUM completions in flight */
-    AIO_WAIT_WHILE(&blk->wait,
-            blk_get_aio_context(blk),
-            atomic_mb_read(&blk->in_flight) > 0);
+    AIO_WAIT_WHILE(blk_get_aio_context(blk),
+                   atomic_mb_read(&blk->in_flight) > 0);
 
     if (bs) {
         bdrv_drained_end(bs);
@@ -1611,8 +1618,7 @@ void blk_drain_all(void)
         aio_context_acquire(ctx);
 
         /* We may have -ENOMEDIUM completions in flight */
-        AIO_WAIT_WHILE(&blk->wait, ctx,
-                atomic_mb_read(&blk->in_flight) > 0);
+        AIO_WAIT_WHILE(ctx, atomic_mb_read(&blk->in_flight) > 0);
 
         aio_context_release(ctx);
     }
@@ -2189,6 +2195,13 @@ static void blk_root_drained_begin(BdrvChild *child)
     }
 }
 
+static bool blk_root_drained_poll(BdrvChild *child)
+{
+    BlockBackend *blk = child->opaque;
+    assert(blk->quiesce_counter);
+    return !!blk->in_flight;
+}
+
 static void blk_root_drained_end(BdrvChild *child)
 {
     BlockBackend *blk = child->opaque;