[Qemu-devel] [PATCH 11/15] block: Remove wrong bdrv_set_aio_context() calls

[Kevin Wolf <kwolf@redhat.com>]

The mirror and commit block jobs use bdrv_set_aio_context() to move
their filter node into the right AioContext before hooking it up in the
graph. Similarly, bdrv_open_backing_file() explicitly moves the backing
file node into the right AioContext first.

This isn't necessary any more, they get automatically moved into the
right context now when attaching them.

However, in the case of bdrv_open_backing_file() with a node reference,
it's actually not only unnecessary, but even wrong: The unchecked
bdrv_set_aio_context() changes the AioContext of the child node even if
other parents require it to retain the old context. So this is not only
a simplification, but a bug fix, too.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1684342
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c        | 1 -
 block/commit.c | 2 --
 block/mirror.c | 1 -
 3 files changed, 4 deletions(-)

diff --git a/block.c b/block.c
index 19268f52f8..e9261c650d 100644
--- a/block.c
+++ b/block.c
@@ -2539,7 +2539,6 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
         ret = -EINVAL;
         goto free_exit;
     }
-    bdrv_set_aio_context(backing_hd, bdrv_get_aio_context(bs));
 
     if (implicit_backing) {
         bdrv_refresh_filename(backing_hd);
diff --git a/block/commit.c b/block/commit.c
index 4d519506d6..c815def89a 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -301,7 +301,6 @@ void commit_start(const char *job_id, BlockDriverState *bs,
         commit_top_bs->implicit = true;
     }
     commit_top_bs->total_sectors = top->total_sectors;
-    bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top));
 
     bdrv_append(commit_top_bs, top, &local_err);
     if (local_err) {
@@ -443,7 +442,6 @@ int bdrv_commit(BlockDriverState *bs)
         error_report_err(local_err);
         goto ro_cleanup;
     }
-    bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(backing_file_bs));
 
     bdrv_set_backing_hd(commit_top_bs, backing_file_bs, &error_abort);
     bdrv_set_backing_hd(bs, commit_top_bs, &error_abort);
diff --git a/block/mirror.c b/block/mirror.c
index eb96b52de9..f8bdb5b21b 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1543,7 +1543,6 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
                                           BDRV_REQ_NO_FALLBACK;
     bs_opaque = g_new0(MirrorBDSOpaque, 1);
     mirror_top_bs->opaque = bs_opaque;
-    bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
 
     /* bdrv_append takes ownership of the mirror_top_bs reference, need to keep
      * it alive until block_job_create() succeeds even if bs has no parent. */
-- 
2.20.1