[v2,1/3] block: Make bdrv_child_get_parent_aio_context I/O

Commit Message

Hanna Czenczek Nov. 7, 2022, 3:13 p.m. UTC

We want to use bdrv_child_get_parent_aio_context() from
bdrv_parent_drained_{begin,end}_single(), both of which are "I/O or GS"
functions.

Prior to 3ed4f708fe1, all the implementations were I/O code anyway.
3ed4f708fe1 has put block jobs' AioContext field under the job mutex, so
to make child_job_get_parent_aio_context() work in an I/O context, we
need to take that lock there.

Furthermore, blk_root_get_parent_aio_context() is not marked as
anything, but is safe to run in an I/O context, so mark it that way now.
(blk_get_aio_context() is an I/O code function.)

With that done, all implementations explicitly are I/O code, so we can
mark bdrv_child_get_parent_aio_context() as I/O code, too, so callers
know it is safe to run from both GS and I/O contexts.

Signed-off-by: Hanna Reitz <[e-mail]>
---
 include/block/block-global-state.h | 1 -
 include/block/block-io.h           | 2 ++
 include/block/block_int-common.h   | 4 ++--
 block.c                            | 2 +-
 block/block-backend.c              | 1 +
 blockjob.c                         | 3 ++-
 6 files changed, 8 insertions(+), 5 deletions(-)

Patch

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index bb42ed9559..c7bd4a2088 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -220,7 +220,6 @@  void coroutine_fn bdrv_co_lock(BlockDriverState *bs);
  */
 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs);
 
-AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c);
 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
                                    GHashTable *visited, Transaction *tran,
                                    Error **errp);
diff --git a/include/block/block-io.h b/include/block/block-io.h
index 770ddeb7c8..b099d7db45 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -171,6 +171,8 @@  void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event);
  */
 AioContext *bdrv_get_aio_context(BlockDriverState *bs);
 
+AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c);
+
 /**
  * Move the current coroutine to the AioContext of @bs and return the old
  * AioContext of the coroutine. Increase bs->in_flight so that draining @bs
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 5a2cc077a0..31ae91e56e 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -911,8 +911,6 @@  struct BdrvChildClass {
                            GHashTable *visited, Transaction *tran,
                            Error **errp);
 
-    AioContext *(*get_parent_aio_context)(BdrvChild *child);
-
     /*
      * I/O API functions. These functions are thread-safe.
      *
@@ -929,6 +927,8 @@  struct BdrvChildClass {
      */
     const char *(*get_name)(BdrvChild *child);
 
+    AioContext *(*get_parent_aio_context)(BdrvChild *child);
+
     /*
      * If this pair of functions is implemented, the parent doesn't issue new
      * requests after returning from .drained_begin() until .drained_end() is
diff --git a/block.c b/block.c
index 3bd594eb2a..2d6128d80a 100644
--- a/block.c
+++ b/block.c
@@ -1533,7 +1533,7 @@  const BdrvChildClass child_of_bds = {
 
 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c)
 {
-    GLOBAL_STATE_CODE();
+    IO_CODE();
     return c->klass->get_parent_aio_context(c);
 }
 
diff --git a/block/block-backend.c b/block/block-backend.c
index c0c7d56c8d..ed2f4b67a2 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -311,6 +311,7 @@  static void blk_root_detach(BdrvChild *child)
 static AioContext *blk_root_get_parent_aio_context(BdrvChild *c)
 {
     BlockBackend *blk = c->opaque;
+    IO_CODE();
 
     return blk_get_aio_context(blk);
 }
diff --git a/blockjob.c b/blockjob.c
index 2d86014fa5..f51d4e18f3 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -173,7 +173,8 @@  static bool child_job_change_aio_ctx(BdrvChild *c, AioContext *ctx,
 static AioContext *child_job_get_parent_aio_context(BdrvChild *c)
 {
     BlockJob *job = c->opaque;
-    GLOBAL_STATE_CODE();
+    IO_CODE();
+    JOB_LOCK_GUARD();
 
     return job->job.aio_context;
 }