block: remove AioContext locking

This is the big patch that removes
aio_context_acquire()/aio_context_release() from the block layer and
affected block layer users.

There isn't a clean way to split this patch and the reviewers are likely
the same group of people, so I decided to do it in one patch.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-ID: <20231205182011.1976568-7-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -1625,7 +1625,6 @@ static int no_coroutine_fn GRAPH_UNLOCKED
 bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name,
                  QDict *options, int open_flags, Error **errp)
 {
-    AioContext *ctx;
     Error *local_err = NULL;
     int i, ret;
     GLOBAL_STATE_CODE();
@@ -1673,21 +1672,15 @@ bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name,
     bs->supported_read_flags |= BDRV_REQ_REGISTERED_BUF;
     bs->supported_write_flags |= BDRV_REQ_REGISTERED_BUF;
 
-    /* Get the context after .bdrv_open, it can change the context */
-    ctx = bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
-
     ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not refresh total sector count");
-        aio_context_release(ctx);
         return ret;
     }
 
     bdrv_graph_rdlock_main_loop();
     bdrv_refresh_limits(bs, NULL, &local_err);
     bdrv_graph_rdunlock_main_loop();
-    aio_context_release(ctx);
 
     if (local_err) {
         error_propagate(errp, local_err);
@@ -3062,7 +3055,7 @@ bdrv_attach_child_common(BlockDriverState *child_bs,
                          Transaction *tran, Error **errp)
 {
     BdrvChild *new_child;
-    AioContext *parent_ctx, *new_child_ctx;
+    AioContext *parent_ctx;
     AioContext *child_ctx = bdrv_get_aio_context(child_bs);
 
     assert(child_class->get_parent_desc);
@@ -3114,12 +3107,6 @@ bdrv_attach_child_common(BlockDriverState *child_bs,
         }
     }
 
-    new_child_ctx = bdrv_get_aio_context(child_bs);
-    if (new_child_ctx != child_ctx) {
-        aio_context_release(child_ctx);
-        aio_context_acquire(new_child_ctx);
-    }
-
     bdrv_ref(child_bs);
     /*
      * Let every new BdrvChild start with a drained parent. Inserting the child
@@ -3149,11 +3136,6 @@ bdrv_attach_child_common(BlockDriverState *child_bs,
     };
     tran_add(tran, &bdrv_attach_child_common_drv, s);
 
-    if (new_child_ctx != child_ctx) {
-        aio_context_release(new_child_ctx);
-        aio_context_acquire(child_ctx);
-    }
-
     return new_child;
 }
 
@@ -3605,7 +3587,6 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
     int ret = 0;
     bool implicit_backing = false;
     BlockDriverState *backing_hd;
-    AioContext *backing_hd_ctx;
     QDict *options;
     QDict *tmp_parent_options = NULL;
     Error *local_err = NULL;
@@ -3691,11 +3672,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
 
     /* Hook up the backing file link; drop our reference, bs owns the
      * backing_hd reference now */
-    backing_hd_ctx = bdrv_get_aio_context(backing_hd);
-    aio_context_acquire(backing_hd_ctx);
     ret = bdrv_set_backing_hd(bs, backing_hd, errp);
     bdrv_unref(backing_hd);
-    aio_context_release(backing_hd_ctx);
 
     if (ret < 0) {
         goto free_exit;
@@ -3780,7 +3758,6 @@ BdrvChild *bdrv_open_child(const char *filename,
 {
     BlockDriverState *bs;
     BdrvChild *child;
-    AioContext *ctx;
 
     GLOBAL_STATE_CODE();
 
@@ -3791,11 +3768,8 @@ BdrvChild *bdrv_open_child(const char *filename,
     }
 
     bdrv_graph_wrlock();
-    ctx = bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
     child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
                               errp);
-    aio_context_release(ctx);
     bdrv_graph_wrunlock();
 
     return child;
@@ -3881,7 +3855,6 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
     int64_t total_size;
     QemuOpts *opts = NULL;
     BlockDriverState *bs_snapshot = NULL;
-    AioContext *ctx = bdrv_get_aio_context(bs);
     int ret;
 
     GLOBAL_STATE_CODE();
@@ -3890,9 +3863,7 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
        instead of opening 'filename' directly */
 
     /* Get the required size from the image */
-    aio_context_acquire(ctx);
     total_size = bdrv_getlength(bs);
-    aio_context_release(ctx);
 
     if (total_size < 0) {
         error_setg_errno(errp, -total_size, "Could not get image size");
@@ -3927,10 +3898,7 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
         goto out;
     }
 
-    aio_context_acquire(ctx);
     ret = bdrv_append(bs_snapshot, bs, errp);
-    aio_context_release(ctx);
-
     if (ret < 0) {
         bs_snapshot = NULL;
         goto out;
@@ -3974,7 +3942,6 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
     Error *local_err = NULL;
     QDict *snapshot_options = NULL;
     int snapshot_flags = 0;
-    AioContext *ctx = qemu_get_aio_context();
 
     assert(!child_class || !flags);
     assert(!child_class == !parent);
@@ -4115,12 +4082,10 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
             /* Not requesting BLK_PERM_CONSISTENT_READ because we're only
              * looking at the header to guess the image format. This works even
              * in cases where a guest would not see a consistent state. */
-            ctx = bdrv_get_aio_context(file_bs);
-            aio_context_acquire(ctx);
+            AioContext *ctx = bdrv_get_aio_context(file_bs);
             file = blk_new(ctx, 0, BLK_PERM_ALL);
             blk_insert_bs(file, file_bs, &local_err);
             bdrv_unref(file_bs);
-            aio_context_release(ctx);
 
             if (local_err) {
                 goto fail;
@@ -4167,13 +4132,8 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
         goto fail;
     }
 
-    /* The AioContext could have changed during bdrv_open_common() */
-    ctx = bdrv_get_aio_context(bs);
-
     if (file) {
-        aio_context_acquire(ctx);
         blk_unref(file);
-        aio_context_release(ctx);
         file = NULL;
     }
 
@@ -4231,16 +4191,13 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
          * (snapshot_bs); thus, we have to drop the strong reference to bs
          * (which we obtained by calling bdrv_new()). bs will not be deleted,
          * though, because the overlay still has a reference to it. */
-        aio_context_acquire(ctx);
         bdrv_unref(bs);
-        aio_context_release(ctx);
         bs = snapshot_bs;
     }
 
     return bs;
 
 fail:
-    aio_context_acquire(ctx);
     blk_unref(file);
     qobject_unref(snapshot_options);
     qobject_unref(bs->explicit_options);
@@ -4249,14 +4206,11 @@ fail:
     bs->options = NULL;
     bs->explicit_options = NULL;
     bdrv_unref(bs);
-    aio_context_release(ctx);
     error_propagate(errp, local_err);
     return NULL;
 
 close_and_fail:
-    aio_context_acquire(ctx);
     bdrv_unref(bs);
-    aio_context_release(ctx);
     qobject_unref(snapshot_options);
     qobject_unref(options);
     error_propagate(errp, local_err);
@@ -4540,12 +4494,7 @@ void bdrv_reopen_queue_free(BlockReopenQueue *bs_queue)
     if (bs_queue) {
         BlockReopenQueueEntry *bs_entry, *next;
         QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
-            AioContext *ctx = bdrv_get_aio_context(bs_entry->state.bs);
-
-            aio_context_acquire(ctx);
             bdrv_drained_end(bs_entry->state.bs);
-            aio_context_release(ctx);
-
             qobject_unref(bs_entry->state.explicit_options);
             qobject_unref(bs_entry->state.options);
             g_free(bs_entry);
@@ -4577,7 +4526,6 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
 {
     int ret = -1;
     BlockReopenQueueEntry *bs_entry, *next;
-    AioContext *ctx;
     Transaction *tran = tran_new();
     g_autoptr(GSList) refresh_list = NULL;
 
@@ -4586,10 +4534,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
     GLOBAL_STATE_CODE();
 
     QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
-        ctx = bdrv_get_aio_context(bs_entry->state.bs);
-        aio_context_acquire(ctx);
         ret = bdrv_flush(bs_entry->state.bs);
-        aio_context_release(ctx);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Error flushing drive");
             goto abort;
@@ -4598,10 +4543,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
 
     QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
         assert(bs_entry->state.bs->quiesce_counter > 0);
-        ctx = bdrv_get_aio_context(bs_entry->state.bs);
-        aio_context_acquire(ctx);
         ret = bdrv_reopen_prepare(&bs_entry->state, bs_queue, tran, errp);
-        aio_context_release(ctx);
         if (ret < 0) {
             goto abort;
         }
@@ -4644,10 +4586,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
      * to first element.
      */
     QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
-        ctx = bdrv_get_aio_context(bs_entry->state.bs);
-        aio_context_acquire(ctx);
         bdrv_reopen_commit(&bs_entry->state);
-        aio_context_release(ctx);
     }
 
     bdrv_graph_wrlock();
@@ -4658,10 +4597,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
         BlockDriverState *bs = bs_entry->state.bs;
 
         if (bs->drv->bdrv_reopen_commit_post) {
-            ctx = bdrv_get_aio_context(bs);
-            aio_context_acquire(ctx);
             bs->drv->bdrv_reopen_commit_post(&bs_entry->state);
-            aio_context_release(ctx);
         }
     }
 
@@ -4675,10 +4611,7 @@ abort:
 
     QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
         if (bs_entry->prepared) {
-            ctx = bdrv_get_aio_context(bs_entry->state.bs);
-            aio_context_acquire(ctx);
             bdrv_reopen_abort(&bs_entry->state);
-            aio_context_release(ctx);
         }
     }
 
@@ -4691,24 +4624,13 @@ cleanup:
 int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts,
                 Error **errp)
 {
-    AioContext *ctx = bdrv_get_aio_context(bs);
     BlockReopenQueue *queue;
-    int ret;
 
     GLOBAL_STATE_CODE();
 
     queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts);
 
-    if (ctx != qemu_get_aio_context()) {
-        aio_context_release(ctx);
-    }
-    ret = bdrv_reopen_multiple(queue, errp);
-
-    if (ctx != qemu_get_aio_context()) {
-        aio_context_acquire(ctx);
-    }
-
-    return ret;
+    return bdrv_reopen_multiple(queue, errp);
 }
 
 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
@@ -4760,7 +4682,6 @@ bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
     const char *child_name = is_backing ? "backing" : "file";
     QObject *value;
     const char *str;
-    AioContext *ctx, *old_ctx;
     bool has_child;
     int ret;
 
@@ -4844,13 +4765,6 @@ bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
         bdrv_drained_begin(old_child_bs);
     }
 
-    old_ctx = bdrv_get_aio_context(bs);
-    ctx = bdrv_get_aio_context(new_child_bs);
-    if (old_ctx != ctx) {
-        aio_context_release(old_ctx);
-        aio_context_acquire(ctx);
-    }
-
     bdrv_graph_rdunlock_main_loop();
     bdrv_graph_wrlock();
 
@@ -4859,11 +4773,6 @@ bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
 
     bdrv_graph_wrunlock();
 
-    if (old_ctx != ctx) {
-        aio_context_release(ctx);
-        aio_context_acquire(old_ctx);
-    }
-
     if (old_child_bs) {
         bdrv_drained_end(old_child_bs);
         bdrv_unref(old_child_bs);
@@ -5537,7 +5446,6 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
     int ret;
     BdrvChild *child;
     Transaction *tran = tran_new();
-    AioContext *old_context, *new_context = NULL;
 
     GLOBAL_STATE_CODE();
 
@@ -5545,21 +5453,8 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
     assert(!bs_new->backing);
     bdrv_graph_rdunlock_main_loop();
 
-    old_context = bdrv_get_aio_context(bs_top);
     bdrv_drained_begin(bs_top);
-
-    /*
-     * bdrv_drained_begin() requires that only the AioContext of the drained
-     * node is locked, and at this point it can still differ from the AioContext
-     * of bs_top.
-     */
-    new_context = bdrv_get_aio_context(bs_new);
-    aio_context_release(old_context);
-    aio_context_acquire(new_context);
     bdrv_drained_begin(bs_new);
-    aio_context_release(new_context);
-    aio_context_acquire(old_context);
-    new_context = NULL;
 
     bdrv_graph_wrlock();
 
@@ -5571,18 +5466,6 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
         goto out;
     }
 
-    /*
-     * bdrv_attach_child_noperm could change the AioContext of bs_top and
-     * bs_new, but at least they are in the same AioContext now. This is the
-     * AioContext that we need to lock for the rest of the function.
-     */
-    new_context = bdrv_get_aio_context(bs_top);
-
-    if (old_context != new_context) {
-        aio_context_release(old_context);
-        aio_context_acquire(new_context);
-    }
-
     ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp);
     if (ret < 0) {
         goto out;
@@ -5598,11 +5481,6 @@ out:
     bdrv_drained_end(bs_top);
     bdrv_drained_end(bs_new);
 
-    if (new_context && old_context != new_context) {
-        aio_context_release(new_context);
-        aio_context_acquire(old_context);
-    }
-
     return ret;
 }
 
@@ -5697,12 +5575,8 @@ BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *options,
 
     GLOBAL_STATE_CODE();
 
-    aio_context_release(ctx);
-    aio_context_acquire(qemu_get_aio_context());
     new_node_bs = bdrv_new_open_driver_opts(drv, node_name, options, flags,
                                             errp);
-    aio_context_release(qemu_get_aio_context());
-    aio_context_acquire(ctx);
     assert(bdrv_get_aio_context(bs) == ctx);
 
     options = NULL; /* bdrv_new_open_driver() eats options */
@@ -7037,12 +6911,9 @@ void bdrv_activate_all(Error **errp)
     GRAPH_RDLOCK_GUARD_MAINLOOP();
 
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
         int ret;
 
-        aio_context_acquire(aio_context);
         ret = bdrv_activate(bs, errp);
-        aio_context_release(aio_context);
         if (ret < 0) {
             bdrv_next_cleanup(&it);
             return;
@@ -7137,20 +7008,10 @@ int bdrv_inactivate_all(void)
     BlockDriverState *bs = NULL;
     BdrvNextIterator it;
     int ret = 0;
-    GSList *aio_ctxs = NULL, *ctx;
 
     GLOBAL_STATE_CODE();
     GRAPH_RDLOCK_GUARD_MAINLOOP();
 
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
-
-        if (!g_slist_find(aio_ctxs, aio_context)) {
-            aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
-            aio_context_acquire(aio_context);
-        }
-    }
-
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         /* Nodes with BDS parents are covered by recursion from the last
          * parent that gets inactivated. Don't inactivate them a second
@@ -7161,17 +7022,10 @@ int bdrv_inactivate_all(void)
         ret = bdrv_inactivate_recurse(bs);
         if (ret < 0) {
             bdrv_next_cleanup(&it);
-            goto out;
+            break;
         }
     }
 
-out:
-    for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
-        AioContext *aio_context = ctx->data;
-        aio_context_release(aio_context);
-    }
-    g_slist_free(aio_ctxs);
-
     return ret;
 }
 
@@ -7257,11 +7111,8 @@ void bdrv_unref(BlockDriverState *bs)
 static void bdrv_schedule_unref_bh(void *opaque)
 {
     BlockDriverState *bs = opaque;
-    AioContext *ctx = bdrv_get_aio_context(bs);
 
-    aio_context_acquire(ctx);
     bdrv_unref(bs);
-    aio_context_release(ctx);
 }
 
 /*
@@ -7398,8 +7249,6 @@ void bdrv_img_create(const char *filename, const char *fmt,
         return;
     }
 
-    aio_context_acquire(qemu_get_aio_context());
-
     /* Create parameter list */
     create_opts = qemu_opts_append(create_opts, drv->create_opts);
     create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
@@ -7549,7 +7398,6 @@ out:
     qemu_opts_del(opts);
     qemu_opts_free(create_opts);
     error_propagate(errp, local_err);
-    aio_context_release(qemu_get_aio_context());
 }
 
 AioContext *bdrv_get_aio_context(BlockDriverState *bs)
@@ -7585,29 +7433,12 @@ void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx)
 
 void coroutine_fn bdrv_co_lock(BlockDriverState *bs)
 {
-    AioContext *ctx = bdrv_get_aio_context(bs);
-
-    /* In the main thread, bs->aio_context won't change concurrently */
-    assert(qemu_get_current_aio_context() == qemu_get_aio_context());
-
-    /*
-     * We're in coroutine context, so we already hold the lock of the main
-     * loop AioContext. Don't lock it twice to avoid deadlocks.
-     */
-    assert(qemu_in_coroutine());
-    if (ctx != qemu_get_aio_context()) {
-        aio_context_acquire(ctx);
-    }
+    /* TODO removed in next patch */
 }
 
 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs)
 {
-    AioContext *ctx = bdrv_get_aio_context(bs);
-
-    assert(qemu_in_coroutine());
-    if (ctx != qemu_get_aio_context()) {
-        aio_context_release(ctx);
-    }
+    /* TODO removed in next patch */
 }
 
 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
@@ -7728,21 +7559,8 @@ static void bdrv_set_aio_context_commit(void *opaque)
     BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
     BlockDriverState *bs = (BlockDriverState *) state->bs;
     AioContext *new_context = state->new_ctx;
-    AioContext *old_context = bdrv_get_aio_context(bs);
 
-    /*
-     * Take the old AioContex when detaching it from bs.
-     * At this point, new_context lock is already acquired, and we are now
-     * also taking old_context. This is safe as long as bdrv_detach_aio_context
-     * does not call AIO_POLL_WHILE().
-     */
-    if (old_context != qemu_get_aio_context()) {
-        aio_context_acquire(old_context);
-    }
     bdrv_detach_aio_context(bs);
-    if (old_context != qemu_get_aio_context()) {
-        aio_context_release(old_context);
-    }
     bdrv_attach_aio_context(bs, new_context);
 }
 
@@ -7827,7 +7645,6 @@ int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
     Transaction *tran;
     GHashTable *visited;
     int ret;
-    AioContext *old_context = bdrv_get_aio_context(bs);
     GLOBAL_STATE_CODE();
 
     /*
@@ -7857,34 +7674,7 @@ int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
         return -EPERM;
     }
 
-    /*
-     * Release old AioContext, it won't be needed anymore, as all
-     * bdrv_drained_begin() have been called already.
-     */
-    if (qemu_get_aio_context() != old_context) {
-        aio_context_release(old_context);
-    }
-
-    /*
-     * Acquire new AioContext since bdrv_drained_end() is going to be called
-     * after we switched all nodes in the new AioContext, and the function
-     * assumes that the lock of the bs is always taken.
-     */
-    if (qemu_get_aio_context() != ctx) {
-        aio_context_acquire(ctx);
-    }
-
     tran_commit(tran);
-
-    if (qemu_get_aio_context() != ctx) {
-        aio_context_release(ctx);
-    }
-
-    /* Re-acquire the old AioContext, since the caller takes and releases it. */
-    if (qemu_get_aio_context() != old_context) {
-        aio_context_acquire(old_context);
-    }
-
     return 0;
 }
 
@@ -8006,7 +7796,6 @@ BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
                                         const char *node_name, Error **errp)
 {
     BlockDriverState *to_replace_bs = bdrv_find_node(node_name);
-    AioContext *aio_context;
 
     GLOBAL_STATE_CODE();
 
@@ -8015,12 +7804,8 @@ BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
         return NULL;
     }
 
-    aio_context = bdrv_get_aio_context(to_replace_bs);
-    aio_context_acquire(aio_context);
-
     if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
-        to_replace_bs = NULL;
-        goto out;
+        return NULL;
     }
 
     /* We don't want arbitrary node of the BDS chain to be replaced only the top
@@ -8033,12 +7818,9 @@ BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
                    "because it cannot be guaranteed that doing so would not "
                    "lead to an abrupt change of visible data",
                    node_name, parent_bs->node_name);
-        to_replace_bs = NULL;
-        goto out;
+        return NULL;
     }
 
-out:
-    aio_context_release(aio_context);
     return to_replace_bs;
 }
 

block/block-backend.c

@@ -429,7 +429,6 @@ BlockBackend *blk_new_open(const char *filename, const char *reference,
 {
     BlockBackend *blk;
     BlockDriverState *bs;
-    AioContext *ctx;
     uint64_t perm = 0;
     uint64_t shared = BLK_PERM_ALL;
 
@@ -459,23 +458,18 @@ BlockBackend *blk_new_open(const char *filename, const char *reference,
         shared = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
     }
 
-    aio_context_acquire(qemu_get_aio_context());
     bs = bdrv_open(filename, reference, options, flags, errp);
-    aio_context_release(qemu_get_aio_context());
     if (!bs) {
         return NULL;
     }
 
     /* bdrv_open() could have moved bs to a different AioContext */
-    ctx = bdrv_get_aio_context(bs);
     blk = blk_new(bdrv_get_aio_context(bs), perm, shared);
     blk->perm = perm;
     blk->shared_perm = shared;
 
-    aio_context_acquire(ctx);
     blk_insert_bs(blk, bs, errp);
     bdrv_unref(bs);
-    aio_context_release(ctx);
 
     if (!blk->root) {
         blk_unref(blk);
@@ -577,13 +571,9 @@ void blk_remove_all_bs(void)
     GLOBAL_STATE_CODE();
 
     while ((blk = blk_all_next(blk)) != NULL) {
-        AioContext *ctx = blk_get_aio_context(blk);
-
-        aio_context_acquire(ctx);
         if (blk->root) {
             blk_remove_bs(blk);
         }
-        aio_context_release(ctx);
     }
 }
 
@@ -2736,20 +2726,16 @@ int blk_commit_all(void)
     GRAPH_RDLOCK_GUARD_MAINLOOP();
 
     while ((blk = blk_all_next(blk)) != NULL) {
-        AioContext *aio_context = blk_get_aio_context(blk);
         BlockDriverState *unfiltered_bs = bdrv_skip_filters(blk_bs(blk));
 
-        aio_context_acquire(aio_context);
         if (blk_is_inserted(blk) && bdrv_cow_child(unfiltered_bs)) {
             int ret;
 
             ret = bdrv_commit(unfiltered_bs);
             if (ret < 0) {
-                aio_context_release(aio_context);
                 return ret;
             }
         }
-        aio_context_release(aio_context);
     }
     return 0;
 }

block/copy-before-write.c

@@ -412,7 +412,6 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
     int64_t cluster_size;
     g_autoptr(BlockdevOptions) full_opts = NULL;
     BlockdevOptionsCbw *opts;
-    AioContext *ctx;
     int ret;
 
     full_opts = cbw_parse_options(options, errp);
@@ -435,15 +434,11 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
 
     GRAPH_RDLOCK_GUARD_MAINLOOP();
 
-    ctx = bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
-
     if (opts->bitmap) {
         bitmap = block_dirty_bitmap_lookup(opts->bitmap->node,
                                            opts->bitmap->name, NULL, errp);
         if (!bitmap) {
-            ret = -EINVAL;
-            goto out;
+            return -EINVAL;
         }
     }
     s->on_cbw_error = opts->has_on_cbw_error ? opts->on_cbw_error :
@@ -461,24 +456,21 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
     s->bcs = block_copy_state_new(bs->file, s->target, bitmap, errp);
     if (!s->bcs) {
         error_prepend(errp, "Cannot create block-copy-state: ");
-        ret = -EINVAL;
-        goto out;
+        return -EINVAL;
     }
 
     cluster_size = block_copy_cluster_size(s->bcs);
 
     s->done_bitmap = bdrv_create_dirty_bitmap(bs, cluster_size, NULL, errp);
     if (!s->done_bitmap) {
-        ret = -EINVAL;
-        goto out;
+        return -EINVAL;
     }
     bdrv_disable_dirty_bitmap(s->done_bitmap);
 
     /* s->access_bitmap starts equal to bcs bitmap */
     s->access_bitmap = bdrv_create_dirty_bitmap(bs, cluster_size, NULL, errp);
     if (!s->access_bitmap) {
-        ret = -EINVAL;
-        goto out;
+        return -EINVAL;
     }
     bdrv_disable_dirty_bitmap(s->access_bitmap);
     bdrv_dirty_bitmap_merge_internal(s->access_bitmap,
@@ -487,11 +479,7 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
 
     qemu_co_mutex_init(&s->lock);
     QLIST_INIT(&s->frozen_read_reqs);
-
-    ret = 0;
-out:
-    aio_context_release(ctx);
-    return ret;
+    return 0;
 }
 
 static void cbw_close(BlockDriverState *bs)

block/export/export.c

@@ -114,7 +114,6 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
     }
 
     ctx = bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
 
     if (export->iothread) {
         IOThread *iothread;
@@ -133,8 +132,6 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
         set_context_errp = fixed_iothread ? errp : NULL;
         ret = bdrv_try_change_aio_context(bs, new_ctx, NULL, set_context_errp);
         if (ret == 0) {
-            aio_context_release(ctx);
-            aio_context_acquire(new_ctx);
             ctx = new_ctx;
         } else if (fixed_iothread) {
             goto fail;
@@ -191,8 +188,6 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
     assert(exp->blk != NULL);
 
     QLIST_INSERT_HEAD(&block_exports, exp, next);
-
-    aio_context_release(ctx);
     return exp;
 
 fail:
@@ -200,7 +195,6 @@ fail:
         blk_set_dev_ops(blk, NULL, NULL);
         blk_unref(blk);
     }
-    aio_context_release(ctx);
     if (exp) {
         g_free(exp->id);
         g_free(exp);
@@ -218,9 +212,6 @@ void blk_exp_ref(BlockExport *exp)
 static void blk_exp_delete_bh(void *opaque)
 {
     BlockExport *exp = opaque;
-    AioContext *aio_context = exp->ctx;
-
-    aio_context_acquire(aio_context);
 
     assert(exp->refcount == 0);
     QLIST_REMOVE(exp, next);
@@ -230,8 +221,6 @@ static void blk_exp_delete_bh(void *opaque)
     qapi_event_send_block_export_deleted(exp->id);
     g_free(exp->id);
     g_free(exp);
-
-    aio_context_release(aio_context);
 }
 
 void blk_exp_unref(BlockExport *exp)
@@ -249,22 +238,16 @@ void blk_exp_unref(BlockExport *exp)
  * connections and other internally held references start to shut down. When
  * the function returns, there may still be active references while the export
  * is in the process of shutting down.
- *
- * Acquires exp->ctx internally. Callers must *not* hold the lock.
  */
 void blk_exp_request_shutdown(BlockExport *exp)
 {
-    AioContext *aio_context = exp->ctx;
-
-    aio_context_acquire(aio_context);
-
     /*
      * If the user doesn't own the export any more, it is already shutting
      * down. We must not call .request_shutdown and decrease the refcount a
      * second time.
      */
     if (!exp->user_owned) {
-        goto out;
+        return;
     }
 
     exp->drv->request_shutdown(exp);
@@ -272,9 +255,6 @@ void blk_exp_request_shutdown(BlockExport *exp)
     assert(exp->user_owned);
     exp->user_owned = false;
     blk_exp_unref(exp);
-
-out:
-    aio_context_release(aio_context);
 }
 
 /*

block/io.c

@@ -294,8 +294,6 @@ static void bdrv_co_drain_bh_cb(void *opaque)
     BlockDriverState *bs = data->bs;
 
     if (bs) {
-        AioContext *ctx = bdrv_get_aio_context(bs);
-        aio_context_acquire(ctx);
         bdrv_dec_in_flight(bs);
         if (data->begin) {
             bdrv_do_drained_begin(bs, data->parent, data->poll);
@@ -303,7 +301,6 @@ static void bdrv_co_drain_bh_cb(void *opaque)
             assert(!data->poll);
             bdrv_do_drained_end(bs, data->parent);
         }
-        aio_context_release(ctx);
     } else {
         assert(data->begin);
         bdrv_drain_all_begin();
@@ -320,8 +317,6 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
 {
     BdrvCoDrainData data;
     Coroutine *self = qemu_coroutine_self();
-    AioContext *ctx = bdrv_get_aio_context(bs);
-    AioContext *co_ctx = qemu_coroutine_get_aio_context(self);
 
     /* Calling bdrv_drain() from a BH ensures the current coroutine yields and
      * other coroutines run if they were queued by aio_co_enter(). */
@@ -340,17 +335,6 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
         bdrv_inc_in_flight(bs);
     }
 
-    /*
-     * Temporarily drop the lock across yield or we would get deadlocks.
-     * bdrv_co_drain_bh_cb() reaquires the lock as needed.
-     *
-     * When we yield below, the lock for the current context will be
-     * released, so if this is actually the lock that protects bs, don't drop
-     * it a second time.
-     */
-    if (ctx != co_ctx) {
-        aio_context_release(ctx);
-    }
     replay_bh_schedule_oneshot_event(qemu_get_aio_context(),
                                      bdrv_co_drain_bh_cb, &data);
 
@@ -358,11 +342,6 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
     /* If we are resumed from some other event (such as an aio completion or a
      * timer callback), it is a bug in the caller that should be fixed. */
     assert(data.done);
-
-    /* Reacquire the AioContext of bs if we dropped it */
-    if (ctx != co_ctx) {
-        aio_context_acquire(ctx);
-    }
 }
 
 static void bdrv_do_drained_begin(BlockDriverState *bs, BdrvChild *parent,
@@ -478,13 +457,12 @@ static bool bdrv_drain_all_poll(void)
     GLOBAL_STATE_CODE();
     GRAPH_RDLOCK_GUARD_MAINLOOP();
 
-    /* bdrv_drain_poll() can't make changes to the graph and we are holding the
-     * main AioContext lock, so iterating bdrv_next_all_states() is safe. */
+    /*
+     * bdrv_drain_poll() can't make changes to the graph and we hold the BQL,
+     * so iterating bdrv_next_all_states() is safe.
+     */
     while ((bs = bdrv_next_all_states(bs))) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
-        aio_context_acquire(aio_context);
         result |= bdrv_drain_poll(bs, NULL, true);
-        aio_context_release(aio_context);
     }
 
     return result;
@@ -525,11 +503,7 @@ void bdrv_drain_all_begin_nopoll(void)
     /* Quiesce all nodes, without polling in-flight requests yet. The graph
      * cannot change during this loop. */
     while ((bs = bdrv_next_all_states(bs))) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
-
-        aio_context_acquire(aio_context);
         bdrv_do_drained_begin(bs, NULL, false);
-        aio_context_release(aio_context);
     }
 }
 
@@ -588,11 +562,7 @@ void bdrv_drain_all_end(void)
     }
 
     while ((bs = bdrv_next_all_states(bs))) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
-
-        aio_context_acquire(aio_context);
         bdrv_do_drained_end(bs, NULL);
-        aio_context_release(aio_context);
     }
 
     assert(qemu_get_current_aio_context() == qemu_get_aio_context());
@@ -2368,15 +2338,10 @@ int bdrv_flush_all(void)
     }
 
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
-        int ret;
-
-        aio_context_acquire(aio_context);
-        ret = bdrv_flush(bs);
+        int ret = bdrv_flush(bs);
         if (ret < 0 && !result) {
             result = ret;
         }
-        aio_context_release(aio_context);
     }
 
     return result;

block/mirror.c

@@ -662,7 +662,6 @@ static int mirror_exit_common(Job *job)
     MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);
     BlockJob *bjob = &s->common;
     MirrorBDSOpaque *bs_opaque;
-    AioContext *replace_aio_context = NULL;
     BlockDriverState *src;
     BlockDriverState *target_bs;
     BlockDriverState *mirror_top_bs;
@@ -677,7 +676,6 @@ static int mirror_exit_common(Job *job)
     }
     s->prepared = true;
 
-    aio_context_acquire(qemu_get_aio_context());
     bdrv_graph_rdlock_main_loop();
 
     mirror_top_bs = s->mirror_top_bs;
@@ -742,11 +740,6 @@ static int mirror_exit_common(Job *job)
     }
     bdrv_graph_rdunlock_main_loop();
 
-    if (s->to_replace) {
-        replace_aio_context = bdrv_get_aio_context(s->to_replace);
-        aio_context_acquire(replace_aio_context);
-    }
-
     if (s->should_complete && !abort) {
         BlockDriverState *to_replace = s->to_replace ?: src;
         bool ro = bdrv_is_read_only(to_replace);
@@ -785,9 +778,6 @@ static int mirror_exit_common(Job *job)
         error_free(s->replace_blocker);
         bdrv_unref(s->to_replace);
     }
-    if (replace_aio_context) {
-        aio_context_release(replace_aio_context);
-    }
     g_free(s->replaces);
 
     /*
@@ -811,8 +801,6 @@ static int mirror_exit_common(Job *job)
     bdrv_unref(mirror_top_bs);
     bdrv_unref(src);
 
-    aio_context_release(qemu_get_aio_context());
-
     return ret;
 }
 
@@ -1191,24 +1179,17 @@ static void mirror_complete(Job *job, Error **errp)
 
     /* block all operations on to_replace bs */
     if (s->replaces) {
-        AioContext *replace_aio_context;
-
         s->to_replace = bdrv_find_node(s->replaces);
         if (!s->to_replace) {
             error_setg(errp, "Node name '%s' not found", s->replaces);
             return;
         }
 
-        replace_aio_context = bdrv_get_aio_context(s->to_replace);
-        aio_context_acquire(replace_aio_context);
-
         /* TODO Translate this into child freeze system. */
         error_setg(&s->replace_blocker,
                    "block device is in use by block-job-complete");
         bdrv_op_block_all(s->to_replace, s->replace_blocker);
         bdrv_ref(s->to_replace);
-
-        aio_context_release(replace_aio_context);
     }
 
     s->should_complete = true;

block/monitor/bitmap-qmp-cmds.c

@@ -95,7 +95,6 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
 {
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
-    AioContext *aio_context;
 
     if (!name || name[0] == '\0') {
         error_setg(errp, "Bitmap name cannot be empty");
@@ -107,14 +106,11 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
         return;
     }
 
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-
     if (has_granularity) {
         if (granularity < 512 || !is_power_of_2(granularity)) {
             error_setg(errp, "Granularity must be power of 2 "
                              "and at least 512");
-            goto out;
+            return;
         }
     } else {
         /* Default to cluster size, if available: */
@@ -132,12 +128,12 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
     if (persistent &&
         !bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp))
     {
-        goto out;
+        return;
     }
 
     bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
     if (bitmap == NULL) {
-        goto out;
+        return;
     }
 
     if (disabled) {
@@ -145,9 +141,6 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
     }
 
     bdrv_dirty_bitmap_set_persistence(bitmap, persistent);
-
-out:
-    aio_context_release(aio_context);
 }
 
 BdrvDirtyBitmap *block_dirty_bitmap_remove(const char *node, const char *name,
@@ -157,7 +150,6 @@ BdrvDirtyBitmap *block_dirty_bitmap_remove(const char *node, const char *name,
 {
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
-    AioContext *aio_context;
 
     GLOBAL_STATE_CODE();
 
@@ -166,19 +158,14 @@ BdrvDirtyBitmap *block_dirty_bitmap_remove(const char *node, const char *name,
         return NULL;
     }
 
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-
     if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_BUSY | BDRV_BITMAP_RO,
                                 errp)) {
-        aio_context_release(aio_context);
         return NULL;
     }
 
     if (bdrv_dirty_bitmap_get_persistence(bitmap) &&
         bdrv_remove_persistent_dirty_bitmap(bs, name, errp) < 0)
     {
-        aio_context_release(aio_context);
         return NULL;
     }
 
@@ -190,7 +177,6 @@ BdrvDirtyBitmap *block_dirty_bitmap_remove(const char *node, const char *name,
         *bitmap_bs = bs;
     }
 
-    aio_context_release(aio_context);
     return release ? NULL : bitmap;
 }
 

block/monitor/block-hmp-cmds.c

@@ -141,7 +141,6 @@ void hmp_drive_del(Monitor *mon, const QDict *qdict)
     const char *id = qdict_get_str(qdict, "id");
     BlockBackend *blk;
     BlockDriverState *bs;
-    AioContext *aio_context;
     Error *local_err = NULL;
 
     GLOBAL_STATE_CODE();
@@ -168,14 +167,10 @@ void hmp_drive_del(Monitor *mon, const QDict *qdict)
         return;
     }
 
-    aio_context = blk_get_aio_context(blk);
-    aio_context_acquire(aio_context);
-
     bs = blk_bs(blk);
     if (bs) {
         if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_DRIVE_DEL, &local_err)) {
             error_report_err(local_err);
-            aio_context_release(aio_context);
             return;
         }
 
@@ -196,8 +191,6 @@ void hmp_drive_del(Monitor *mon, const QDict *qdict)
     } else {
         blk_unref(blk);
     }
-
-    aio_context_release(aio_context);
 }
 
 void hmp_commit(Monitor *mon, const QDict *qdict)
@@ -213,7 +206,6 @@ void hmp_commit(Monitor *mon, const QDict *qdict)
         ret = blk_commit_all();
     } else {
         BlockDriverState *bs;
-        AioContext *aio_context;
 
         blk = blk_by_name(device);
         if (!blk) {
@@ -222,18 +214,13 @@ void hmp_commit(Monitor *mon, const QDict *qdict)
         }
 
         bs = bdrv_skip_implicit_filters(blk_bs(blk));
-        aio_context = bdrv_get_aio_context(bs);
-        aio_context_acquire(aio_context);
 
         if (!blk_is_available(blk)) {
             error_report("Device '%s' has no medium", device);
-            aio_context_release(aio_context);
             return;
         }
 
         ret = bdrv_commit(bs);
-
-        aio_context_release(aio_context);
     }
     if (ret < 0) {
         error_report("'commit' error for '%s': %s", device, strerror(-ret));
@@ -560,7 +547,6 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict)
     BlockBackend *blk = NULL;
     BlockDriverState *bs = NULL;
     BlockBackend *local_blk = NULL;
-    AioContext *ctx = NULL;
     bool qdev = qdict_get_try_bool(qdict, "qdev", false);
     const char *device = qdict_get_str(qdict, "device");
     const char *command = qdict_get_str(qdict, "command");
@@ -582,9 +568,6 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict)
         }
     }
 
-    ctx = blk ? blk_get_aio_context(blk) : bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
-
     if (bs) {
         blk = local_blk = blk_new(bdrv_get_aio_context(bs), 0, BLK_PERM_ALL);
         ret = blk_insert_bs(blk, bs, &err);
@@ -622,11 +605,6 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict)
 
 fail:
     blk_unref(local_blk);
-
-    if (ctx) {
-        aio_context_release(ctx);
-    }
-
     hmp_handle_error(mon, err);
 }
 
@@ -882,7 +860,6 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
     int nb_sns, i;
     int total;
     int *global_snapshots;
-    AioContext *aio_context;
 
     typedef struct SnapshotEntry {
         QEMUSnapshotInfo sn;
@@ -909,11 +886,8 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
         error_report_err(err);
         return;
     }
-    aio_context = bdrv_get_aio_context(bs);
 
-    aio_context_acquire(aio_context);
     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
-    aio_context_release(aio_context);
 
     if (nb_sns < 0) {
         monitor_printf(mon, "bdrv_snapshot_list: error %d\n", nb_sns);
@@ -924,9 +898,7 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
         int bs1_nb_sns = 0;
         ImageEntry *ie;
         SnapshotEntry *se;
-        AioContext *ctx = bdrv_get_aio_context(bs1);
 
-        aio_context_acquire(ctx);
         if (bdrv_can_snapshot(bs1)) {
             sn = NULL;
             bs1_nb_sns = bdrv_snapshot_list(bs1, &sn);
@@ -944,7 +916,6 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
             }
             g_free(sn);
         }
-        aio_context_release(ctx);
     }
 
     if (no_snapshot) {

block/qapi-sysemu.c

@@ -174,7 +174,6 @@ blockdev_remove_medium(const char *device, const char *id, Error **errp)
 {
     BlockBackend *blk;
     BlockDriverState *bs;
-    AioContext *aio_context;
     bool has_attached_device;
 
     GLOBAL_STATE_CODE();
@@ -204,13 +203,10 @@ blockdev_remove_medium(const char *device, const char *id, Error **errp)
         return;
     }
 
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-
     bdrv_graph_rdlock_main_loop();
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_EJECT, errp)) {
         bdrv_graph_rdunlock_main_loop();
-        goto out;
+        return;
     }
     bdrv_graph_rdunlock_main_loop();
 
@@ -223,9 +219,6 @@ blockdev_remove_medium(const char *device, const char *id, Error **errp)
          * value passed here (i.e. false). */
         blk_dev_change_media_cb(blk, false, &error_abort);
     }
-
-out:
-    aio_context_release(aio_context);
 }
 
 void qmp_blockdev_remove_medium(const char *id, Error **errp)
@@ -237,7 +230,6 @@ static void qmp_blockdev_insert_anon_medium(BlockBackend *blk,
                                             BlockDriverState *bs, Error **errp)
 {
     Error *local_err = NULL;
-    AioContext *ctx;
     bool has_device;
     int ret;
 
@@ -259,11 +251,7 @@ static void qmp_blockdev_insert_anon_medium(BlockBackend *blk,
         return;
     }
 
-    ctx = bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
     ret = blk_insert_bs(blk, bs, errp);
-    aio_context_release(ctx);
-
     if (ret < 0) {
         return;
     }
@@ -374,9 +362,7 @@ void qmp_blockdev_change_medium(const char *device,
         qdict_put_str(options, "driver", format);
     }
 
-    aio_context_acquire(qemu_get_aio_context());
     medium_bs = bdrv_open(filename, NULL, options, bdrv_flags, errp);
-    aio_context_release(qemu_get_aio_context());
 
     if (!medium_bs) {
         goto fail;
@@ -437,20 +423,16 @@ void qmp_block_set_io_throttle(BlockIOThrottle *arg, Error **errp)
     ThrottleConfig cfg;
     BlockDriverState *bs;
     BlockBackend *blk;
-    AioContext *aio_context;
 
     blk = qmp_get_blk(arg->device, arg->id, errp);
     if (!blk) {
         return;
     }
 
-    aio_context = blk_get_aio_context(blk);
-    aio_context_acquire(aio_context);
-
     bs = blk_bs(blk);
     if (!bs) {
         error_setg(errp, "Device has no medium");
-        goto out;
+        return;
     }
 
     throttle_config_init(&cfg);
@@ -505,7 +487,7 @@ void qmp_block_set_io_throttle(BlockIOThrottle *arg, Error **errp)
     }
 
     if (!throttle_is_valid(&cfg, errp)) {
-        goto out;
+        return;
     }
 
     if (throttle_enabled(&cfg)) {
@@ -522,9 +504,6 @@ void qmp_block_set_io_throttle(BlockIOThrottle *arg, Error **errp)
         /* If all throttling settings are set to 0, disable I/O limits */
         blk_io_limits_disable(blk);
     }
-
-out:
-    aio_context_release(aio_context);
 }
 
 void qmp_block_latency_histogram_set(

block/qapi.c

@@ -234,13 +234,11 @@ bdrv_do_query_node_info(BlockDriverState *bs, BlockNodeInfo *info, Error **errp)
     int ret;
     Error *err = NULL;
 
-    aio_context_acquire(bdrv_get_aio_context(bs));
-
     size = bdrv_getlength(bs);
     if (size < 0) {
         error_setg_errno(errp, -size, "Can't get image size '%s'",
                          bs->exact_filename);
-        goto out;
+        return;
     }
 
     bdrv_refresh_filename(bs);
@@ -265,7 +263,7 @@ bdrv_do_query_node_info(BlockDriverState *bs, BlockNodeInfo *info, Error **errp)
     info->format_specific = bdrv_get_specific_info(bs, &err);
     if (err) {
         error_propagate(errp, err);
-        goto out;
+        return;
     }
     backing_filename = bs->backing_file;
     if (backing_filename[0] != '\0') {
@@ -300,11 +298,8 @@ bdrv_do_query_node_info(BlockDriverState *bs, BlockNodeInfo *info, Error **errp)
         break;
     default:
         error_propagate(errp, err);
-        goto out;
+        return;
     }
-
-out:
-    aio_context_release(bdrv_get_aio_context(bs));
 }
 
 /**
@@ -709,15 +704,10 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
     /* Just to be safe if query_nodes is not always initialized */
     if (has_query_nodes && query_nodes) {
         for (bs = bdrv_next_node(NULL); bs; bs = bdrv_next_node(bs)) {
-            AioContext *ctx = bdrv_get_aio_context(bs);
-
-            aio_context_acquire(ctx);
             QAPI_LIST_APPEND(tail, bdrv_query_bds_stats(bs, false));
-            aio_context_release(ctx);
         }
     } else {
         for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) {
-            AioContext *ctx = blk_get_aio_context(blk);
             BlockStats *s;
             char *qdev;
 
@@ -725,7 +715,6 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
                 continue;
             }
 
-            aio_context_acquire(ctx);
             s = bdrv_query_bds_stats(blk_bs(blk), true);
             s->device = g_strdup(blk_name(blk));
 
@@ -737,7 +726,6 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
             }
 
             bdrv_query_blk_stats(s->stats, blk);
-            aio_context_release(ctx);
 
             QAPI_LIST_APPEND(tail, s);
         }

block/raw-format.c

@@ -470,7 +470,6 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
                     Error **errp)
 {
     BDRVRawState *s = bs->opaque;
-    AioContext *ctx;
     bool has_size;
     uint64_t offset, size;
     BdrvChildRole file_role;
@@ -522,11 +521,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
                 bs->file->bs->filename);
     }
 
-    ctx = bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
     ret = raw_apply_options(bs, s, offset, has_size, size, errp);
-    aio_context_release(ctx);
-
     if (ret < 0) {
         return ret;
     }

block/replication.c

@@ -394,14 +394,7 @@ static void reopen_backing_file(BlockDriverState *bs, bool writable,
     }
 
     if (reopen_queue) {
-        AioContext *ctx = bdrv_get_aio_context(bs);
-        if (ctx != qemu_get_aio_context()) {
-            aio_context_release(ctx);
-        }
         bdrv_reopen_multiple(reopen_queue, errp);
-        if (ctx != qemu_get_aio_context()) {
-            aio_context_acquire(ctx);
-        }
     }
 }
 
@@ -462,14 +455,11 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
     BlockDriverState *top_bs;
     BdrvChild *active_disk, *hidden_disk, *secondary_disk;
     int64_t active_length, hidden_length, disk_length;
-    AioContext *aio_context;
     Error *local_err = NULL;
     BackupPerf perf = { .use_copy_range = true, .max_workers = 1 };
 
     GLOBAL_STATE_CODE();
 
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
     s = bs->opaque;
 
     if (s->stage == BLOCK_REPLICATION_DONE ||
@@ -479,20 +469,17 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
          * Ignore the request because the secondary side of replication
          * doesn't have to do anything anymore.
          */
-        aio_context_release(aio_context);
         return;
     }
 
     if (s->stage != BLOCK_REPLICATION_NONE) {
         error_setg(errp, "Block replication is running or done");
-        aio_context_release(aio_context);
         return;
     }
 
     if (s->mode != mode) {
         error_setg(errp, "The parameter mode's value is invalid, needs %d,"
                    " but got %d", s->mode, mode);
-        aio_context_release(aio_context);
         return;
     }
 
@@ -505,7 +492,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
         if (!active_disk || !active_disk->bs || !active_disk->bs->backing) {
             error_setg(errp, "Active disk doesn't have backing file");
             bdrv_graph_rdunlock_main_loop();
-            aio_context_release(aio_context);
             return;
         }
 
@@ -513,7 +499,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
         if (!hidden_disk->bs || !hidden_disk->bs->backing) {
             error_setg(errp, "Hidden disk doesn't have backing file");
             bdrv_graph_rdunlock_main_loop();
-            aio_context_release(aio_context);
             return;
         }
 
@@ -521,7 +506,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
         if (!secondary_disk->bs || !bdrv_has_blk(secondary_disk->bs)) {
             error_setg(errp, "The secondary disk doesn't have block backend");
             bdrv_graph_rdunlock_main_loop();
-            aio_context_release(aio_context);
             return;
         }
         bdrv_graph_rdunlock_main_loop();
@@ -534,7 +518,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
             active_length != hidden_length || hidden_length != disk_length) {
             error_setg(errp, "Active disk, hidden disk, secondary disk's length"
                        " are not the same");
-            aio_context_release(aio_context);
             return;
         }
 
@@ -546,7 +529,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
             !hidden_disk->bs->drv->bdrv_make_empty) {
             error_setg(errp,
                        "Active disk or hidden disk doesn't support make_empty");
-            aio_context_release(aio_context);
             bdrv_graph_rdunlock_main_loop();
             return;
         }
@@ -556,7 +538,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
         reopen_backing_file(bs, true, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
-            aio_context_release(aio_context);
             return;
         }
 
@@ -569,7 +550,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
         if (local_err) {
             error_propagate(errp, local_err);
             bdrv_graph_wrunlock();
-            aio_context_release(aio_context);
             return;
         }
 
@@ -580,7 +560,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
         if (local_err) {
             error_propagate(errp, local_err);
             bdrv_graph_wrunlock();
-            aio_context_release(aio_context);
             return;
         }
 
@@ -594,7 +573,6 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
             error_setg(errp, "No top_bs or it is invalid");
             bdrv_graph_wrunlock();
             reopen_backing_file(bs, false, NULL);
-            aio_context_release(aio_context);
             return;
         }
         bdrv_op_block_all(top_bs, s->blocker);
@@ -612,13 +590,11 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
         if (local_err) {
             error_propagate(errp, local_err);
             backup_job_cleanup(bs);
-            aio_context_release(aio_context);
             return;
         }
         job_start(&s->backup_job->job);
         break;
     default:
-        aio_context_release(aio_context);
         abort();
     }
 
@@ -629,18 +605,12 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
     }
 
     s->error = 0;
-    aio_context_release(aio_context);
 }
 
 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
 {
     BlockDriverState *bs = rs->opaque;
-    BDRVReplicationState *s;
-    AioContext *aio_context;
-
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-    s = bs->opaque;
+    BDRVReplicationState *s = bs->opaque;
 
     if (s->stage == BLOCK_REPLICATION_DONE ||
         s->stage == BLOCK_REPLICATION_FAILOVER) {
@@ -649,38 +619,28 @@ static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
          * Ignore the request because the secondary side of replication
          * doesn't have to do anything anymore.
          */
-        aio_context_release(aio_context);
         return;
     }
 
     if (s->mode == REPLICATION_MODE_SECONDARY) {
         secondary_do_checkpoint(bs, errp);
     }
-    aio_context_release(aio_context);
 }
 
 static void replication_get_error(ReplicationState *rs, Error **errp)
 {
     BlockDriverState *bs = rs->opaque;
-    BDRVReplicationState *s;
-    AioContext *aio_context;
-
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-    s = bs->opaque;
+    BDRVReplicationState *s = bs->opaque;
 
     if (s->stage == BLOCK_REPLICATION_NONE) {
         error_setg(errp, "Block replication is not running");
-        aio_context_release(aio_context);
         return;
     }
 
     if (s->error) {
         error_setg(errp, "I/O error occurred");
-        aio_context_release(aio_context);
         return;
     }
-    aio_context_release(aio_context);
 }
 
 static void replication_done(void *opaque, int ret)
@@ -708,12 +668,7 @@ static void replication_done(void *opaque, int ret)
 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
 {
     BlockDriverState *bs = rs->opaque;
-    BDRVReplicationState *s;
-    AioContext *aio_context;
-
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-    s = bs->opaque;
+    BDRVReplicationState *s = bs->opaque;
 
     if (s->stage == BLOCK_REPLICATION_DONE ||
         s->stage == BLOCK_REPLICATION_FAILOVER) {
@@ -722,13 +677,11 @@ static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
          * Ignore the request because the secondary side of replication
          * doesn't have to do anything anymore.
          */
-        aio_context_release(aio_context);
         return;
     }
 
     if (s->stage != BLOCK_REPLICATION_RUNNING) {
         error_setg(errp, "Block replication is not running");
-        aio_context_release(aio_context);
         return;
     }
 
@@ -744,15 +697,12 @@ static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
          * disk, secondary disk in backup_job_completed().
          */
         if (s->backup_job) {
-            aio_context_release(aio_context);
             job_cancel_sync(&s->backup_job->job, true);
-            aio_context_acquire(aio_context);
         }
 
         if (!failover) {
             secondary_do_checkpoint(bs, errp);
             s->stage = BLOCK_REPLICATION_DONE;
-            aio_context_release(aio_context);
             return;
         }
 
@@ -765,10 +715,8 @@ static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
         bdrv_graph_rdunlock_main_loop();
         break;
     default:
-        aio_context_release(aio_context);
         abort();
     }
-    aio_context_release(aio_context);
 }
 
 static const char *const replication_strong_runtime_opts[] = {

block/snapshot.c

@@ -527,9 +527,7 @@ static bool GRAPH_RDLOCK bdrv_all_snapshots_includes_bs(BlockDriverState *bs)
     return bdrv_has_blk(bs) || QLIST_EMPTY(&bs->parents);
 }
 
-/* Group operations. All block drivers are involved.
- * These functions will properly handle dataplane (take aio_context_acquire
- * when appropriate for appropriate block drivers) */
+/* Group operations. All block drivers are involved. */
 
 bool bdrv_all_can_snapshot(bool has_devices, strList *devices,
                            Error **errp)
@@ -547,14 +545,11 @@ bool bdrv_all_can_snapshot(bool has_devices, strList *devices,
     iterbdrvs = bdrvs;
     while (iterbdrvs) {
         BlockDriverState *bs = iterbdrvs->data;
-        AioContext *ctx = bdrv_get_aio_context(bs);
         bool ok = true;
 
-        aio_context_acquire(ctx);
         if (devices || bdrv_all_snapshots_includes_bs(bs)) {
             ok = bdrv_can_snapshot(bs);
         }
-        aio_context_release(ctx);
         if (!ok) {
             error_setg(errp, "Device '%s' is writable but does not support "
                        "snapshots", bdrv_get_device_or_node_name(bs));
@@ -584,18 +579,15 @@ int bdrv_all_delete_snapshot(const char *name,
     iterbdrvs = bdrvs;
     while (iterbdrvs) {
         BlockDriverState *bs = iterbdrvs->data;
-        AioContext *ctx = bdrv_get_aio_context(bs);
         QEMUSnapshotInfo sn1, *snapshot = &sn1;
         int ret = 0;
 
-        aio_context_acquire(ctx);
         if ((devices || bdrv_all_snapshots_includes_bs(bs)) &&
             bdrv_snapshot_find(bs, snapshot, name) >= 0)
         {
             ret = bdrv_snapshot_delete(bs, snapshot->id_str,
                                        snapshot->name, errp);
         }
-        aio_context_release(ctx);
         if (ret < 0) {
             error_prepend(errp, "Could not delete snapshot '%s' on '%s': ",
                           name, bdrv_get_device_or_node_name(bs));
@@ -630,17 +622,14 @@ int bdrv_all_goto_snapshot(const char *name,
     iterbdrvs = bdrvs;
     while (iterbdrvs) {
         BlockDriverState *bs = iterbdrvs->data;
-        AioContext *ctx = bdrv_get_aio_context(bs);
         bool all_snapshots_includes_bs;
 
-        aio_context_acquire(ctx);
         bdrv_graph_rdlock_main_loop();
         all_snapshots_includes_bs = bdrv_all_snapshots_includes_bs(bs);
         bdrv_graph_rdunlock_main_loop();
 
         ret = (devices || all_snapshots_includes_bs) ?
               bdrv_snapshot_goto(bs, name, errp) : 0;
-        aio_context_release(ctx);
         if (ret < 0) {
             bdrv_graph_rdlock_main_loop();
             error_prepend(errp, "Could not load snapshot '%s' on '%s': ",
@@ -672,15 +661,12 @@ int bdrv_all_has_snapshot(const char *name,
     iterbdrvs = bdrvs;
     while (iterbdrvs) {
         BlockDriverState *bs = iterbdrvs->data;
-        AioContext *ctx = bdrv_get_aio_context(bs);
         QEMUSnapshotInfo sn;
         int ret = 0;
 
-        aio_context_acquire(ctx);
         if (devices || bdrv_all_snapshots_includes_bs(bs)) {
             ret = bdrv_snapshot_find(bs, &sn, name);
         }
-        aio_context_release(ctx);
         if (ret < 0) {
             if (ret == -ENOENT) {
                 return 0;
@@ -717,10 +703,8 @@ int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
     iterbdrvs = bdrvs;
     while (iterbdrvs) {
         BlockDriverState *bs = iterbdrvs->data;
-        AioContext *ctx = bdrv_get_aio_context(bs);
         int ret = 0;
 
-        aio_context_acquire(ctx);
         if (bs == vm_state_bs) {
             sn->vm_state_size = vm_state_size;
             ret = bdrv_snapshot_create(bs, sn);
@@ -728,7 +712,6 @@ int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
             sn->vm_state_size = 0;
             ret = bdrv_snapshot_create(bs, sn);
         }
-        aio_context_release(ctx);
         if (ret < 0) {
             error_setg(errp, "Could not create snapshot '%s' on '%s'",
                        sn->name, bdrv_get_device_or_node_name(bs));
@@ -759,13 +742,10 @@ BlockDriverState *bdrv_all_find_vmstate_bs(const char *vmstate_bs,
     iterbdrvs = bdrvs;
     while (iterbdrvs) {
         BlockDriverState *bs = iterbdrvs->data;
-        AioContext *ctx = bdrv_get_aio_context(bs);
         bool found = false;
 
-        aio_context_acquire(ctx);
         found = (devices || bdrv_all_snapshots_includes_bs(bs)) &&
             bdrv_can_snapshot(bs);
-        aio_context_release(ctx);
 
         if (vmstate_bs) {
             if (g_str_equal(vmstate_bs,

block/write-threshold.c

@@ -33,7 +33,6 @@ void qmp_block_set_write_threshold(const char *node_name,
                                    Error **errp)
 {
     BlockDriverState *bs;
-    AioContext *aio_context;
 
     bs = bdrv_find_node(node_name);
     if (!bs) {
@@ -41,12 +40,7 @@ void qmp_block_set_write_threshold(const char *node_name,
         return;
     }
 
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-
     bdrv_write_threshold_set(bs, threshold_bytes);
-
-    aio_context_release(aio_context);
 }
 
 void bdrv_write_threshold_check_write(BlockDriverState *bs, int64_t offset,

blockjob.c

@@ -198,9 +198,7 @@ void block_job_remove_all_bdrv(BlockJob *job)
      * one to make sure that such a concurrent access does not attempt
      * to process an already freed BdrvChild.
      */
-    aio_context_release(job->job.aio_context);
     bdrv_graph_wrlock();
-    aio_context_acquire(job->job.aio_context);
     while (job->nodes) {
         GSList *l = job->nodes;
         BdrvChild *c = l->data;
@@ -234,28 +232,12 @@ int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs,
                        uint64_t perm, uint64_t shared_perm, Error **errp)
 {
     BdrvChild *c;
-    AioContext *ctx = bdrv_get_aio_context(bs);
-    bool need_context_ops;
     GLOBAL_STATE_CODE();
 
     bdrv_ref(bs);
 
-    need_context_ops = ctx != job->job.aio_context;
-
-    if (need_context_ops) {
-        if (job->job.aio_context != qemu_get_aio_context()) {
-            aio_context_release(job->job.aio_context);
-        }
-        aio_context_acquire(ctx);
-    }
     c = bdrv_root_attach_child(bs, name, &child_job, 0, perm, shared_perm, job,
                                errp);
-    if (need_context_ops) {
-        aio_context_release(ctx);
-        if (job->job.aio_context != qemu_get_aio_context()) {
-            aio_context_acquire(job->job.aio_context);
-        }
-    }
     if (c == NULL) {
         return -EPERM;
     }

hw/block/dataplane/virtio-blk.c

@@ -124,7 +124,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
     VirtIOBlockDataPlane *s = vblk->dataplane;
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vblk)));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
-    AioContext *old_context;
     unsigned i;
     unsigned nvqs = s->conf->num_queues;
     Error *local_err = NULL;
@@ -178,10 +177,7 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
 
     trace_virtio_blk_data_plane_start(s);
 
-    old_context = blk_get_aio_context(s->conf->conf.blk);
-    aio_context_acquire(old_context);
     r = blk_set_aio_context(s->conf->conf.blk, s->ctx, &local_err);
-    aio_context_release(old_context);
     if (r < 0) {
         error_report_err(local_err);
         goto fail_aio_context;
@@ -208,13 +204,11 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
 
     /* Get this show started by hooking up our callbacks */
     if (!blk_in_drain(s->conf->conf.blk)) {
-        aio_context_acquire(s->ctx);
         for (i = 0; i < nvqs; i++) {
             VirtQueue *vq = virtio_get_queue(s->vdev, i);
 
             virtio_queue_aio_attach_host_notifier(vq, s->ctx);
         }
-        aio_context_release(s->ctx);
     }
     return 0;
 
@@ -314,8 +308,6 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
      */
     vblk->dataplane_started = false;
 
-    aio_context_acquire(s->ctx);
-
     /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
     blk_drain(s->conf->conf.blk);
 
@@ -325,8 +317,6 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
      */
     blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL);
 
-    aio_context_release(s->ctx);
-
     /* Clean up guest notifier (irq) */
     k->set_guest_notifiers(qbus->parent, nvqs, false);
 

hw/block/dataplane/xen-block.c

@@ -260,8 +260,6 @@ static void xen_block_complete_aio(void *opaque, int ret)
     XenBlockRequest *request = opaque;
     XenBlockDataPlane *dataplane = request->dataplane;
 
-    aio_context_acquire(dataplane->ctx);
-
     if (ret != 0) {
         error_report("%s I/O error",
                      request->req.operation == BLKIF_OP_READ ?
@@ -273,10 +271,10 @@ static void xen_block_complete_aio(void *opaque, int ret)
     if (request->presync) {
         request->presync = 0;
         xen_block_do_aio(request);
-        goto done;
+        return;
     }
     if (request->aio_inflight > 0) {
-        goto done;
+        return;
     }
 
     switch (request->req.operation) {
@@ -318,9 +316,6 @@ static void xen_block_complete_aio(void *opaque, int ret)
     if (dataplane->more_work) {
         qemu_bh_schedule(dataplane->bh);
     }
-
-done:
-    aio_context_release(dataplane->ctx);
 }
 
 static bool xen_block_split_discard(XenBlockRequest *request,
@@ -601,9 +596,7 @@ static void xen_block_dataplane_bh(void *opaque)
 {
     XenBlockDataPlane *dataplane = opaque;
 
-    aio_context_acquire(dataplane->ctx);
     xen_block_handle_requests(dataplane);
-    aio_context_release(dataplane->ctx);
 }
 
 static bool xen_block_dataplane_event(void *opaque)
@@ -703,10 +696,8 @@ void xen_block_dataplane_stop(XenBlockDataPlane *dataplane)
         xen_block_dataplane_detach(dataplane);
     }
 
-    aio_context_acquire(dataplane->ctx);
     /* Xen doesn't have multiple users for nodes, so this can't fail */
     blk_set_aio_context(dataplane->blk, qemu_get_aio_context(), &error_abort);
-    aio_context_release(dataplane->ctx);
 
     /*
      * Now that the context has been moved onto the main thread, cancel
@@ -752,7 +743,6 @@ void xen_block_dataplane_start(XenBlockDataPlane *dataplane,
 {
     ERRP_GUARD();
     XenDevice *xendev = dataplane->xendev;
-    AioContext *old_context;
     unsigned int ring_size;
     unsigned int i;
 
@@ -836,11 +826,8 @@ void xen_block_dataplane_start(XenBlockDataPlane *dataplane,
         goto stop;
     }
 
-    old_context = blk_get_aio_context(dataplane->blk);
-    aio_context_acquire(old_context);
     /* If other users keep the BlockBackend in the iothread, that's ok */
     blk_set_aio_context(dataplane->blk, dataplane->ctx, NULL);
-    aio_context_release(old_context);
 
     if (!blk_in_drain(dataplane->blk)) {
         xen_block_dataplane_attach(dataplane);

hw/block/virtio-blk.c

@@ -1210,17 +1210,13 @@ static void virtio_blk_dma_restart_cb(void *opaque, bool running,
 static void virtio_blk_reset(VirtIODevice *vdev)
 {
     VirtIOBlock *s = VIRTIO_BLK(vdev);
-    AioContext *ctx;
     VirtIOBlockReq *req;
 
     /* Dataplane has stopped... */
     assert(!s->dataplane_started);
 
     /* ...but requests may still be in flight. */
-    ctx = blk_get_aio_context(s->blk);
-    aio_context_acquire(ctx);
     blk_drain(s->blk);
-    aio_context_release(ctx);
 
     /* We drop queued requests after blk_drain() because blk_drain() itself can
      * produce them. */
@@ -1250,10 +1246,6 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
     uint64_t capacity;
     int64_t length;
     int blk_size = conf->logical_block_size;
-    AioContext *ctx;
-
-    ctx = blk_get_aio_context(s->blk);
-    aio_context_acquire(ctx);
 
     blk_get_geometry(s->blk, &capacity);
     memset(&blkcfg, 0, sizeof(blkcfg));
@@ -1277,7 +1269,6 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
      * per track (cylinder).
      */
     length = blk_getlength(s->blk);
-    aio_context_release(ctx);
     if (length > 0 && length / conf->heads / conf->secs % blk_size) {
         blkcfg.geometry.sectors = conf->secs & ~s->sector_mask;
     } else {
@@ -1344,9 +1335,7 @@ static void virtio_blk_set_config(VirtIODevice *vdev, const uint8_t *config)
 
     memcpy(&blkcfg, config, s->config_size);
 
-    aio_context_acquire(blk_get_aio_context(s->blk));
     blk_set_enable_write_cache(s->blk, blkcfg.wce != 0);
-    aio_context_release(blk_get_aio_context(s->blk));
 }
 
 static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features,
@@ -1414,11 +1403,9 @@ static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
      * s->blk would erroneously be placed in writethrough mode.
      */
     if (!virtio_vdev_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE)) {
-        aio_context_acquire(blk_get_aio_context(s->blk));
         blk_set_enable_write_cache(s->blk,
                                    virtio_vdev_has_feature(vdev,
                                                            VIRTIO_BLK_F_WCE));
-        aio_context_release(blk_get_aio_context(s->blk));
     }
 }
 

hw/core/qdev-properties-system.c

@@ -120,9 +120,7 @@ static void set_drive_helper(Object *obj, Visitor *v, const char *name,
                        "node");
         }
 
-        aio_context_acquire(ctx);
         blk_replace_bs(blk, bs, errp);
-        aio_context_release(ctx);
         return;
     }
 
@@ -148,10 +146,7 @@ static void set_drive_helper(Object *obj, Visitor *v, const char *name,
                           0, BLK_PERM_ALL);
             blk_created = true;
 
-            aio_context_acquire(ctx);
             ret = blk_insert_bs(blk, bs, errp);
-            aio_context_release(ctx);
-
             if (ret < 0) {
                 goto fail;
             }
@@ -207,12 +202,8 @@ static void release_drive(Object *obj, const char *name, void *opaque)
     BlockBackend **ptr = object_field_prop_ptr(obj, prop);
 
     if (*ptr) {
-        AioContext *ctx = blk_get_aio_context(*ptr);
-
-        aio_context_acquire(ctx);
         blockdev_auto_del(*ptr);
         blk_detach_dev(*ptr, dev);
-        aio_context_release(ctx);
     }
 }
 

include/block/block-global-state.h

@@ -31,11 +31,10 @@
 /*
  * Global state (GS) API. These functions run under the BQL.
  *
- * If a function modifies the graph, it also uses drain and/or
- * aio_context_acquire/release to be sure it has unique access.
- * aio_context locking is needed together with BQL because of
- * the thread-safe I/O API that concurrently runs and accesses
- * the graph without the BQL.
+ * If a function modifies the graph, it also uses the graph lock to be sure it
+ * has unique access. The graph lock is needed together with BQL because of the
+ * thread-safe I/O API that concurrently runs and accesses the graph without
+ * the BQL.
  *
  * It is important to note that not all of these functions are
  * necessarily limited to running under the BQL, but they would

include/block/block-io.h

@@ -31,8 +31,7 @@
 
 /*
  * I/O API functions. These functions are thread-safe, and therefore
- * can run in any thread as long as the thread has called
- * aio_context_acquire/release().
+ * can run in any thread.
  *
  * These functions can only call functions from I/O and Common categories,
  * but can be invoked by GS, "I/O or GS" and I/O APIs.

include/block/snapshot.h

@@ -86,8 +86,6 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
 
 /*
  * Group operations. All block drivers are involved.
- * These functions will properly handle dataplane (take aio_context_acquire
- * when appropriate for appropriate block drivers
  */
 
 bool bdrv_all_can_snapshot(bool has_devices, strList *devices,

job.c

@@ -464,12 +464,8 @@ void job_unref_locked(Job *job)
         assert(!job->txn);
 
         if (job->driver->free) {
-            AioContext *aio_context = job->aio_context;
             job_unlock();
-            /* FIXME: aiocontext lock is required because cb calls blk_unref */
-            aio_context_acquire(aio_context);
             job->driver->free(job);
-            aio_context_release(aio_context);
             job_lock();
         }
 
@@ -840,12 +836,10 @@ static void job_clean(Job *job)
 
 /*
  * Called with job_mutex held, but releases it temporarily.
- * Takes AioContext lock internally to invoke a job->driver callback.
  */
 static int job_finalize_single_locked(Job *job)
 {
     int job_ret;
-    AioContext *ctx = job->aio_context;
 
     assert(job_is_completed_locked(job));
 
@@ -854,7 +848,6 @@ static int job_finalize_single_locked(Job *job)
 
     job_ret = job->ret;
     job_unlock();
-    aio_context_acquire(ctx);
 
     if (!job_ret) {
         job_commit(job);
@@ -867,7 +860,6 @@ static int job_finalize_single_locked(Job *job)
         job->cb(job->opaque, job_ret);
     }
 
-    aio_context_release(ctx);
     job_lock();
 
     /* Emit events only if we actually started */
@@ -886,17 +878,13 @@ static int job_finalize_single_locked(Job *job)
 
 /*
  * Called with job_mutex held, but releases it temporarily.
- * Takes AioContext lock internally to invoke a job->driver callback.
  */
 static void job_cancel_async_locked(Job *job, bool force)
 {
-    AioContext *ctx = job->aio_context;
     GLOBAL_STATE_CODE();
     if (job->driver->cancel) {
         job_unlock();
-        aio_context_acquire(ctx);
         force = job->driver->cancel(job, force);
-        aio_context_release(ctx);
         job_lock();
     } else {
         /* No .cancel() means the job will behave as if force-cancelled */
@@ -931,7 +919,6 @@ static void job_cancel_async_locked(Job *job, bool force)
 
 /*
  * Called with job_mutex held, but releases it temporarily.
- * Takes AioContext lock internally to invoke a job->driver callback.
  */
 static void job_completed_txn_abort_locked(Job *job)
 {
@@ -979,15 +966,12 @@ static void job_completed_txn_abort_locked(Job *job)
 static int job_prepare_locked(Job *job)
 {
     int ret;
-    AioContext *ctx = job->aio_context;
 
     GLOBAL_STATE_CODE();
 
     if (job->ret == 0 && job->driver->prepare) {
         job_unlock();
-        aio_context_acquire(ctx);
         ret = job->driver->prepare(job);
-        aio_context_release(ctx);
         job_lock();
         job->ret = ret;
         job_update_rc_locked(job);

migration/block.c

@@ -66,7 +66,7 @@ typedef struct BlkMigDevState {
     /* Protected by block migration lock.  */
     int64_t completed_sectors;
 
-    /* During migration this is protected by iothread lock / AioContext.
+    /* During migration this is protected by bdrv_dirty_bitmap_lock().
      * Allocation and free happen during setup and cleanup respectively.
      */
     BdrvDirtyBitmap *dirty_bitmap;
@@ -101,7 +101,7 @@ typedef struct BlkMigState {
     int prev_progress;
     int bulk_completed;
 
-    /* Lock must be taken _inside_ the iothread lock and any AioContexts.  */
+    /* Lock must be taken _inside_ the iothread lock.  */
     QemuMutex lock;
 } BlkMigState;
 
@@ -270,7 +270,6 @@ static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
 
     if (bmds->shared_base) {
         qemu_mutex_lock_iothread();
-        aio_context_acquire(blk_get_aio_context(bb));
         /* Skip unallocated sectors; intentionally treats failure or
          * partial sector as an allocated sector */
         while (cur_sector < total_sectors &&
@@ -281,7 +280,6 @@ static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
             }
             cur_sector += count >> BDRV_SECTOR_BITS;
         }
-        aio_context_release(blk_get_aio_context(bb));
         qemu_mutex_unlock_iothread();
     }
 
@@ -313,21 +311,16 @@ static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
     block_mig_state.submitted++;
     blk_mig_unlock();
 
-    /* We do not know if bs is under the main thread (and thus does
-     * not acquire the AioContext when doing AIO) or rather under
-     * dataplane.  Thus acquire both the iothread mutex and the
-     * AioContext.
-     *
-     * This is ugly and will disappear when we make bdrv_* thread-safe,
-     * without the need to acquire the AioContext.
+    /*
+     * The migration thread does not have an AioContext. Lock the BQL so that
+     * I/O runs in the main loop AioContext (see
+     * qemu_get_current_aio_context()).
      */
     qemu_mutex_lock_iothread();
-    aio_context_acquire(blk_get_aio_context(bmds->blk));
     bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, cur_sector * BDRV_SECTOR_SIZE,
                             nr_sectors * BDRV_SECTOR_SIZE);
     blk->aiocb = blk_aio_preadv(bb, cur_sector * BDRV_SECTOR_SIZE, &blk->qiov,
                                 0, blk_mig_read_cb, blk);
-    aio_context_release(blk_get_aio_context(bmds->blk));
     qemu_mutex_unlock_iothread();
 
     bmds->cur_sector = cur_sector + nr_sectors;
@@ -512,7 +505,7 @@ static void blk_mig_reset_dirty_cursor(void)
     }
 }
 
-/* Called with iothread lock and AioContext taken.  */
+/* Called with iothread lock taken.  */
 
 static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
                                  int is_async)
@@ -606,9 +599,7 @@ static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
     int ret = 1;
 
     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
-        aio_context_acquire(blk_get_aio_context(bmds->blk));
         ret = mig_save_device_dirty(f, bmds, is_async);
-        aio_context_release(blk_get_aio_context(bmds->blk));
         if (ret <= 0) {
             break;
         }
@@ -666,9 +657,9 @@ static int64_t get_remaining_dirty(void)
     int64_t dirty = 0;
 
     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
-        aio_context_acquire(blk_get_aio_context(bmds->blk));
+        bdrv_dirty_bitmap_lock(bmds->dirty_bitmap);
         dirty += bdrv_get_dirty_count(bmds->dirty_bitmap);
-        aio_context_release(blk_get_aio_context(bmds->blk));
+        bdrv_dirty_bitmap_unlock(bmds->dirty_bitmap);
     }
 
     return dirty;
@@ -681,7 +672,6 @@ static void block_migration_cleanup_bmds(void)
 {
     BlkMigDevState *bmds;
     BlockDriverState *bs;
-    AioContext *ctx;
 
     unset_dirty_tracking();
 
@@ -693,13 +683,7 @@ static void block_migration_cleanup_bmds(void)
             bdrv_op_unblock_all(bs, bmds->blocker);
         }
         error_free(bmds->blocker);
-
-        /* Save ctx, because bmds->blk can disappear during blk_unref.  */
-        ctx = blk_get_aio_context(bmds->blk);
-        aio_context_acquire(ctx);
         blk_unref(bmds->blk);
-        aio_context_release(ctx);
-
         g_free(bmds->blk_name);
         g_free(bmds->aio_bitmap);
         g_free(bmds);

migration/migration-hmp-cmds.c

@@ -852,14 +852,11 @@ static void vm_completion(ReadLineState *rs, const char *str)
 
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         SnapshotInfoList *snapshots, *snapshot;
-        AioContext *ctx = bdrv_get_aio_context(bs);
         bool ok = false;
 
-        aio_context_acquire(ctx);
         if (bdrv_can_snapshot(bs)) {
             ok = bdrv_query_snapshot_info_list(bs, &snapshots, NULL) == 0;
         }
-        aio_context_release(ctx);
         if (!ok) {
             continue;
         }

migration/savevm.c

@@ -3049,7 +3049,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
     int saved_vm_running;
     uint64_t vm_state_size;
     g_autoptr(GDateTime) now = g_date_time_new_now_local();
-    AioContext *aio_context;
 
     GLOBAL_STATE_CODE();
 
@@ -3092,7 +3091,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
     if (bs == NULL) {
         return false;
     }
-    aio_context = bdrv_get_aio_context(bs);
 
     saved_vm_running = runstate_is_running();
 
@@ -3101,8 +3099,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
 
     bdrv_drain_all_begin();
 
-    aio_context_acquire(aio_context);
-
     memset(sn, 0, sizeof(*sn));
 
     /* fill auxiliary fields */
@@ -3139,14 +3135,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
         goto the_end;
     }
 
-    /* The bdrv_all_create_snapshot() call that follows acquires the AioContext
-     * for itself.  BDRV_POLL_WHILE() does not support nested locking because
-     * it only releases the lock once.  Therefore synchronous I/O will deadlock
-     * unless we release the AioContext before bdrv_all_create_snapshot().
-     */
-    aio_context_release(aio_context);
-    aio_context = NULL;
-
     ret = bdrv_all_create_snapshot(sn, bs, vm_state_size,
                                    has_devices, devices, errp);
     if (ret < 0) {
@@ -3157,10 +3145,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
     ret = 0;
 
  the_end:
-    if (aio_context) {
-        aio_context_release(aio_context);
-    }
-
     bdrv_drain_all_end();
 
     if (saved_vm_running) {
@@ -3258,7 +3242,6 @@ bool load_snapshot(const char *name, const char *vmstate,
     QEMUSnapshotInfo sn;
     QEMUFile *f;
     int ret;
-    AioContext *aio_context;
     MigrationIncomingState *mis = migration_incoming_get_current();
 
     if (!bdrv_all_can_snapshot(has_devices, devices, errp)) {
@@ -3278,12 +3261,9 @@ bool load_snapshot(const char *name, const char *vmstate,
     if (!bs_vm_state) {
         return false;
     }
-    aio_context = bdrv_get_aio_context(bs_vm_state);
 
     /* Don't even try to load empty VM states */
-    aio_context_acquire(aio_context);
     ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
-    aio_context_release(aio_context);
     if (ret < 0) {
         return false;
     } else if (sn.vm_state_size == 0) {
@@ -3320,10 +3300,8 @@ bool load_snapshot(const char *name, const char *vmstate,
         ret = -EINVAL;
         goto err_drain;
     }
-    aio_context_acquire(aio_context);
     ret = qemu_loadvm_state(f);
     migration_incoming_state_destroy();
-    aio_context_release(aio_context);
 
     bdrv_drain_all_end();
 

net/colo-compare.c

@@ -1439,12 +1439,10 @@ static void colo_compare_finalize(Object *obj)
     qemu_bh_delete(s->event_bh);
 
     AioContext *ctx = iothread_get_aio_context(s->iothread);
-    aio_context_acquire(ctx);
     AIO_WAIT_WHILE(ctx, !s->out_sendco.done);
     if (s->notify_dev) {
         AIO_WAIT_WHILE(ctx, !s->notify_sendco.done);
     }
-    aio_context_release(ctx);
 
     /* Release all unhandled packets after compare thead exited */
     g_queue_foreach(&s->conn_list, colo_flush_packets, s);

qemu-img.c

@@ -960,7 +960,6 @@ static int img_commit(int argc, char **argv)
     Error *local_err = NULL;
     CommonBlockJobCBInfo cbi;
     bool image_opts = false;
-    AioContext *aio_context;
     int64_t rate_limit = 0;
 
     fmt = NULL;
@@ -1078,12 +1077,9 @@ static int img_commit(int argc, char **argv)
         .bs   = bs,
     };
 
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
     commit_active_start("commit", bs, base_bs, JOB_DEFAULT, rate_limit,
                         BLOCKDEV_ON_ERROR_REPORT, NULL, common_block_job_cb,
                         &cbi, false, &local_err);
-    aio_context_release(aio_context);
     if (local_err) {
         goto done;
     }

qemu-io.c

@@ -414,15 +414,7 @@ static void prep_fetchline(void *opaque)
 
 static int do_qemuio_command(const char *cmd)
 {
-    int ret;
-    AioContext *ctx =
-        qemuio_blk ? blk_get_aio_context(qemuio_blk) : qemu_get_aio_context();
-
-    aio_context_acquire(ctx);
-    ret = qemuio_command(qemuio_blk, cmd);
-    aio_context_release(ctx);
-
-    return ret;
+    return qemuio_command(qemuio_blk, cmd);
 }
 
 static int command_loop(void)

qemu-nbd.c

@@ -1123,9 +1123,7 @@ int main(int argc, char **argv)
         qdict_put_str(raw_opts, "file", bs->node_name);
         qdict_put_int(raw_opts, "offset", dev_offset);
 
-        aio_context_acquire(qemu_get_aio_context());
         bs = bdrv_open(NULL, NULL, raw_opts, flags, &error_fatal);
-        aio_context_release(qemu_get_aio_context());
 
         blk_remove_bs(blk);
         blk_insert_bs(blk, bs, &error_fatal);

replay/replay-debugging.c

@@ -144,7 +144,6 @@ static char *replay_find_nearest_snapshot(int64_t icount,
     char *ret = NULL;
     int rv;
     int nb_sns, i;
-    AioContext *aio_context;
 
     *snapshot_icount = -1;
 
@@ -152,11 +151,8 @@ static char *replay_find_nearest_snapshot(int64_t icount,
     if (!bs) {
         goto fail;
     }
-    aio_context = bdrv_get_aio_context(bs);
 
-    aio_context_acquire(aio_context);
     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
-    aio_context_release(aio_context);
 
     for (i = 0; i < nb_sns; i++) {
         rv = bdrv_all_has_snapshot(sn_tab[i].name, false, NULL, NULL);

scripts/block-coroutine-wrapper.py

@@ -278,12 +278,9 @@ def gen_no_co_wrapper(func: FuncDecl) -> str:
 static void {name}_bh(void *opaque)
 {{
     {struct_name} *s = opaque;
-    AioContext *ctx = {func.gen_ctx('s->')};
 
 {graph_lock}
-    aio_context_acquire(ctx);
     {func.get_result}{name}({ func.gen_list('s->{name}') });
-    aio_context_release(ctx);
 {graph_unlock}
 
     aio_co_wake(s->co);

tests/tsan/suppressions.tsan

@@ -4,7 +4,6 @@
 
 # TSan reports a double lock on RECURSIVE mutexes.
 # Since the recursive lock is intentional, we choose to ignore it.
-mutex:aio_context_acquire
 mutex:pthread_mutex_lock
 
 # TSan reports a race between pthread_mutex_init() and

tests/unit/test-bdrv-drain.c

@@ -179,13 +179,7 @@ static void do_drain_end(enum drain_type drain_type, BlockDriverState *bs)
 
 static void do_drain_begin_unlocked(enum drain_type drain_type, BlockDriverState *bs)
 {
-    if (drain_type != BDRV_DRAIN_ALL) {
-        aio_context_acquire(bdrv_get_aio_context(bs));
-    }
     do_drain_begin(drain_type, bs);
-    if (drain_type != BDRV_DRAIN_ALL) {
-        aio_context_release(bdrv_get_aio_context(bs));
-    }
 }
 
 static BlockBackend * no_coroutine_fn test_setup(void)
@@ -209,13 +203,7 @@ static BlockBackend * no_coroutine_fn test_setup(void)
 
 static void do_drain_end_unlocked(enum drain_type drain_type, BlockDriverState *bs)
 {
-    if (drain_type != BDRV_DRAIN_ALL) {
-        aio_context_acquire(bdrv_get_aio_context(bs));
-    }
     do_drain_end(drain_type, bs);
-    if (drain_type != BDRV_DRAIN_ALL) {
-        aio_context_release(bdrv_get_aio_context(bs));
-    }
 }
 
 /*
@@ -520,12 +508,8 @@ static void test_iothread_main_thread_bh(void *opaque)
 {
     struct test_iothread_data *data = opaque;
 
-    /* Test that the AioContext is not yet locked in a random BH that is
-     * executed during drain, otherwise this would deadlock. */
-    aio_context_acquire(bdrv_get_aio_context(data->bs));
     bdrv_flush(data->bs);
     bdrv_dec_in_flight(data->bs); /* incremented by test_iothread_common() */
-    aio_context_release(bdrv_get_aio_context(data->bs));
 }
 
 /*
@@ -567,7 +551,6 @@ static void test_iothread_common(enum drain_type drain_type, int drain_thread)
     blk_set_disable_request_queuing(blk, true);
 
     blk_set_aio_context(blk, ctx_a, &error_abort);
-    aio_context_acquire(ctx_a);
 
     s->bh_indirection_ctx = ctx_b;
 
@@ -582,8 +565,6 @@ static void test_iothread_common(enum drain_type drain_type, int drain_thread)
     g_assert(acb != NULL);
     g_assert_cmpint(aio_ret, ==, -EINPROGRESS);
 
-    aio_context_release(ctx_a);
-
     data = (struct test_iothread_data) {
         .bs         = bs,
         .drain_type = drain_type,
@@ -592,10 +573,6 @@ static void test_iothread_common(enum drain_type drain_type, int drain_thread)
 
     switch (drain_thread) {
     case 0:
-        if (drain_type != BDRV_DRAIN_ALL) {
-            aio_context_acquire(ctx_a);
-        }
-
         /*
          * Increment in_flight so that do_drain_begin() waits for
          * test_iothread_main_thread_bh(). This prevents the race between
@@ -613,20 +590,10 @@ static void test_iothread_common(enum drain_type drain_type, int drain_thread)
         do_drain_begin(drain_type, bs);
         g_assert_cmpint(bs->in_flight, ==, 0);
 
-        if (drain_type != BDRV_DRAIN_ALL) {
-            aio_context_release(ctx_a);
-        }
         qemu_event_wait(&done_event);
-        if (drain_type != BDRV_DRAIN_ALL) {
-            aio_context_acquire(ctx_a);
-        }
 
         g_assert_cmpint(aio_ret, ==, 0);
         do_drain_end(drain_type, bs);
-
-        if (drain_type != BDRV_DRAIN_ALL) {
-            aio_context_release(ctx_a);
-        }
         break;
     case 1:
         co = qemu_coroutine_create(test_iothread_drain_co_entry, &data);
@@ -637,9 +604,7 @@ static void test_iothread_common(enum drain_type drain_type, int drain_thread)
         g_assert_not_reached();
     }
 
-    aio_context_acquire(ctx_a);
     blk_set_aio_context(blk, qemu_get_aio_context(), &error_abort);
-    aio_context_release(ctx_a);
 
     bdrv_unref(bs);
     blk_unref(blk);
@@ -757,7 +722,6 @@ static void test_blockjob_common_drain_node(enum drain_type drain_type,
     BlockJob *job;
     TestBlockJob *tjob;
     IOThread *iothread = NULL;
-    AioContext *ctx;
     int ret;
 
     src = bdrv_new_open_driver(&bdrv_test, "source", BDRV_O_RDWR,
@@ -787,11 +751,11 @@ static void test_blockjob_common_drain_node(enum drain_type drain_type,
     }
 
     if (use_iothread) {
+        AioContext *ctx;
+
         iothread = iothread_new();
         ctx = iothread_get_aio_context(iothread);
         blk_set_aio_context(blk_src, ctx, &error_abort);
-    } else {
-        ctx = qemu_get_aio_context();
     }
 
     target = bdrv_new_open_driver(&bdrv_test, "target", BDRV_O_RDWR,
@@ -800,7 +764,6 @@ static void test_blockjob_common_drain_node(enum drain_type drain_type,
     blk_insert_bs(blk_target, target, &error_abort);
     blk_set_allow_aio_context_change(blk_target, true);
 
-    aio_context_acquire(ctx);
     tjob = block_job_create("job0", &test_job_driver, NULL, src,
                             0, BLK_PERM_ALL,
                             0, 0, NULL, NULL, &error_abort);
@@ -821,7 +784,6 @@ static void test_blockjob_common_drain_node(enum drain_type drain_type,
         tjob->prepare_ret = -EIO;
         break;
     }
-    aio_context_release(ctx);
 
     job_start(&job->job);
 
@@ -912,12 +874,10 @@ static void test_blockjob_common_drain_node(enum drain_type drain_type,
     }
     g_assert_cmpint(ret, ==, (result == TEST_JOB_SUCCESS ? 0 : -EIO));
 
-    aio_context_acquire(ctx);
     if (use_iothread) {
         blk_set_aio_context(blk_src, qemu_get_aio_context(), &error_abort);
         assert(blk_get_aio_context(blk_target) == qemu_get_aio_context());
     }
-    aio_context_release(ctx);
 
     blk_unref(blk_src);
     blk_unref(blk_target);
@@ -1401,9 +1361,7 @@ static void test_append_to_drained(void)
     g_assert_cmpint(base_s->drain_count, ==, 1);
     g_assert_cmpint(base->in_flight, ==, 0);
 
-    aio_context_acquire(qemu_get_aio_context());
     bdrv_append(overlay, base, &error_abort);
-    aio_context_release(qemu_get_aio_context());
 
     g_assert_cmpint(base->in_flight, ==, 0);
     g_assert_cmpint(overlay->in_flight, ==, 0);
@@ -1438,16 +1396,11 @@ static void test_set_aio_context(void)
 
     bdrv_drained_begin(bs);
     bdrv_try_change_aio_context(bs, ctx_a, NULL, &error_abort);
-
-    aio_context_acquire(ctx_a);
     bdrv_drained_end(bs);
 
     bdrv_drained_begin(bs);
     bdrv_try_change_aio_context(bs, ctx_b, NULL, &error_abort);
-    aio_context_release(ctx_a);
-    aio_context_acquire(ctx_b);
     bdrv_try_change_aio_context(bs, qemu_get_aio_context(), NULL, &error_abort);
-    aio_context_release(ctx_b);
     bdrv_drained_end(bs);
 
     bdrv_unref(bs);

tests/unit/test-bdrv-graph-mod.c

@@ -142,10 +142,8 @@ static void test_update_perm_tree(void)
                       BDRV_CHILD_DATA, &error_abort);
     bdrv_graph_wrunlock();
 
-    aio_context_acquire(qemu_get_aio_context());
     ret = bdrv_append(filter, bs, NULL);
     g_assert_cmpint(ret, <, 0);
-    aio_context_release(qemu_get_aio_context());
 
     bdrv_unref(filter);
     blk_unref(root);
@@ -211,9 +209,7 @@ static void test_should_update_child(void)
     bdrv_attach_child(filter, target, "target", &child_of_bds,
                       BDRV_CHILD_DATA, &error_abort);
     bdrv_graph_wrunlock();
-    aio_context_acquire(qemu_get_aio_context());
     bdrv_append(filter, bs, &error_abort);
-    aio_context_release(qemu_get_aio_context());
 
     bdrv_graph_rdlock_main_loop();
     g_assert(target->backing->bs == bs);
@@ -440,9 +436,7 @@ static void test_append_greedy_filter(void)
                       &error_abort);
     bdrv_graph_wrunlock();
 
-    aio_context_acquire(qemu_get_aio_context());
     bdrv_append(fl, base, &error_abort);
-    aio_context_release(qemu_get_aio_context());
     bdrv_unref(fl);
     bdrv_unref(top);
 }

tests/unit/test-block-iothread.c

@@ -483,7 +483,6 @@ static void test_sync_op(const void *opaque)
     bdrv_graph_rdunlock_main_loop();
 
     blk_set_aio_context(blk, ctx, &error_abort);
-    aio_context_acquire(ctx);
     if (t->fn) {
         t->fn(c);
     }
@@ -491,7 +490,6 @@ static void test_sync_op(const void *opaque)
         t->blkfn(blk);
     }
     blk_set_aio_context(blk, qemu_get_aio_context(), &error_abort);
-    aio_context_release(ctx);
 
     bdrv_unref(bs);
     blk_unref(blk);
@@ -576,9 +574,7 @@ static void test_attach_blockjob(void)
         aio_poll(qemu_get_aio_context(), false);
     }
 
-    aio_context_acquire(ctx);
     blk_set_aio_context(blk, qemu_get_aio_context(), &error_abort);
-    aio_context_release(ctx);
 
     tjob->n = 0;
     while (tjob->n == 0) {
@@ -595,9 +591,7 @@ static void test_attach_blockjob(void)
     WITH_JOB_LOCK_GUARD() {
         job_complete_sync_locked(&tjob->common.job, &error_abort);
     }
-    aio_context_acquire(ctx);
     blk_set_aio_context(blk, qemu_get_aio_context(), &error_abort);
-    aio_context_release(ctx);
 
     bdrv_unref(bs);
     blk_unref(blk);
@@ -654,9 +648,7 @@ static void test_propagate_basic(void)
 
     /* Switch the AioContext back */
     main_ctx = qemu_get_aio_context();
-    aio_context_acquire(ctx);
     blk_set_aio_context(blk, main_ctx, &error_abort);
-    aio_context_release(ctx);
     g_assert(blk_get_aio_context(blk) == main_ctx);
     g_assert(bdrv_get_aio_context(bs_a) == main_ctx);
     g_assert(bdrv_get_aio_context(bs_verify) == main_ctx);
@@ -732,9 +724,7 @@ static void test_propagate_diamond(void)
 
     /* Switch the AioContext back */
     main_ctx = qemu_get_aio_context();
-    aio_context_acquire(ctx);
     blk_set_aio_context(blk, main_ctx, &error_abort);
-    aio_context_release(ctx);
     g_assert(blk_get_aio_context(blk) == main_ctx);
     g_assert(bdrv_get_aio_context(bs_verify) == main_ctx);
     g_assert(bdrv_get_aio_context(bs_a) == main_ctx);
@@ -764,13 +754,11 @@ static void test_propagate_mirror(void)
                                   &error_abort);
 
     /* Start a mirror job */
-    aio_context_acquire(main_ctx);
     mirror_start("job0", src, target, NULL, JOB_DEFAULT, 0, 0, 0,
                  MIRROR_SYNC_MODE_NONE, MIRROR_OPEN_BACKING_CHAIN, false,
                  BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
                  false, "filter_node", MIRROR_COPY_MODE_BACKGROUND,
                  &error_abort);
-    aio_context_release(main_ctx);
 
     WITH_JOB_LOCK_GUARD() {
         job = job_get_locked("job0");
@@ -785,9 +773,7 @@ static void test_propagate_mirror(void)
     g_assert(job->aio_context == ctx);
 
     /* Change the AioContext of target */
-    aio_context_acquire(ctx);
     bdrv_try_change_aio_context(target, main_ctx, NULL, &error_abort);
-    aio_context_release(ctx);
     g_assert(bdrv_get_aio_context(src) == main_ctx);
     g_assert(bdrv_get_aio_context(target) == main_ctx);
     g_assert(bdrv_get_aio_context(filter) == main_ctx);
@@ -805,10 +791,8 @@ static void test_propagate_mirror(void)
     g_assert(bdrv_get_aio_context(filter) == main_ctx);
 
     /* ...unless we explicitly allow it */
-    aio_context_acquire(ctx);
     blk_set_allow_aio_context_change(blk, true);
     bdrv_try_change_aio_context(target, ctx, NULL, &error_abort);
-    aio_context_release(ctx);
 
     g_assert(blk_get_aio_context(blk) == ctx);
     g_assert(bdrv_get_aio_context(src) == ctx);
@@ -817,10 +801,8 @@ static void test_propagate_mirror(void)
 
     job_cancel_sync_all();
 
-    aio_context_acquire(ctx);
     blk_set_aio_context(blk, main_ctx, &error_abort);
     bdrv_try_change_aio_context(target, main_ctx, NULL, &error_abort);
-    aio_context_release(ctx);
 
     blk_unref(blk);
     bdrv_unref(src);
@@ -836,7 +818,6 @@ static void test_attach_second_node(void)
     BlockDriverState *bs, *filter;
     QDict *options;
 
-    aio_context_acquire(main_ctx);
     blk = blk_new(ctx, BLK_PERM_ALL, BLK_PERM_ALL);
     bs = bdrv_new_open_driver(&bdrv_test, "base", BDRV_O_RDWR, &error_abort);
     blk_insert_bs(blk, bs, &error_abort);
@@ -846,15 +827,12 @@ static void test_attach_second_node(void)
     qdict_put_str(options, "file", "base");
 
     filter = bdrv_open(NULL, NULL, options, BDRV_O_RDWR, &error_abort);
-    aio_context_release(main_ctx);
 
     g_assert(blk_get_aio_context(blk) == ctx);
     g_assert(bdrv_get_aio_context(bs) == ctx);
     g_assert(bdrv_get_aio_context(filter) == ctx);
 
-    aio_context_acquire(ctx);
     blk_set_aio_context(blk, main_ctx, &error_abort);
-    aio_context_release(ctx);
     g_assert(blk_get_aio_context(blk) == main_ctx);
     g_assert(bdrv_get_aio_context(bs) == main_ctx);
     g_assert(bdrv_get_aio_context(filter) == main_ctx);
@@ -868,11 +846,9 @@ static void test_attach_preserve_blk_ctx(void)
 {
     IOThread *iothread = iothread_new();
     AioContext *ctx = iothread_get_aio_context(iothread);
-    AioContext *main_ctx = qemu_get_aio_context();
     BlockBackend *blk;
     BlockDriverState *bs;
 
-    aio_context_acquire(main_ctx);
     blk = blk_new(ctx, BLK_PERM_ALL, BLK_PERM_ALL);
     bs = bdrv_new_open_driver(&bdrv_test, "base", BDRV_O_RDWR, &error_abort);
     bs->total_sectors = 65536 / BDRV_SECTOR_SIZE;
@@ -881,25 +857,18 @@ static void test_attach_preserve_blk_ctx(void)
     blk_insert_bs(blk, bs, &error_abort);
     g_assert(blk_get_aio_context(blk) == ctx);
     g_assert(bdrv_get_aio_context(bs) == ctx);
-    aio_context_release(main_ctx);
 
     /* Remove the node again */
-    aio_context_acquire(ctx);
     blk_remove_bs(blk);
-    aio_context_release(ctx);
     g_assert(blk_get_aio_context(blk) == ctx);
     g_assert(bdrv_get_aio_context(bs) == qemu_get_aio_context());
 
     /* Re-attach the node */
-    aio_context_acquire(main_ctx);
     blk_insert_bs(blk, bs, &error_abort);
-    aio_context_release(main_ctx);
     g_assert(blk_get_aio_context(blk) == ctx);
     g_assert(bdrv_get_aio_context(bs) == ctx);
 
-    aio_context_acquire(ctx);
     blk_set_aio_context(blk, qemu_get_aio_context(), &error_abort);
-    aio_context_release(ctx);
     bdrv_unref(bs);
     blk_unref(blk);
 }

tests/unit/test-blockjob.c

@@ -228,7 +228,6 @@ static void cancel_common(CancelJob *s)
     BlockJob *job = &s->common;
     BlockBackend *blk = s->blk;
     JobStatus sts = job->job.status;
-    AioContext *ctx = job->job.aio_context;
 
     job_cancel_sync(&job->job, true);
     WITH_JOB_LOCK_GUARD() {
@@ -240,9 +239,7 @@ static void cancel_common(CancelJob *s)
         job_unref_locked(&job->job);
     }
 
-    aio_context_acquire(ctx);
     destroy_blk(blk);
-    aio_context_release(ctx);
 
 }
 
@@ -391,132 +388,6 @@ static void test_cancel_concluded(void)
     cancel_common(s);
 }
 
-/* (See test_yielding_driver for the job description) */
-typedef struct YieldingJob {
-    BlockJob common;
-    bool should_complete;
-} YieldingJob;
-
-static void yielding_job_complete(Job *job, Error **errp)
-{
-    YieldingJob *s = container_of(job, YieldingJob, common.job);
-    s->should_complete = true;
-    job_enter(job);
-}
-
-static int coroutine_fn yielding_job_run(Job *job, Error **errp)
-{
-    YieldingJob *s = container_of(job, YieldingJob, common.job);
-
-    job_transition_to_ready(job);
-
-    while (!s->should_complete) {
-        job_yield(job);
-    }
-
-    return 0;
-}
-
-/*
- * This job transitions immediately to the READY state, and then
- * yields until it is to complete.
- */
-static const BlockJobDriver test_yielding_driver = {
-    .job_driver = {
-        .instance_size  = sizeof(YieldingJob),
-        .free           = block_job_free,
-        .user_resume    = block_job_user_resume,
-        .run            = yielding_job_run,
-        .complete       = yielding_job_complete,
-    },
-};
-
-/*
- * Test that job_complete_locked() works even on jobs that are in a paused
- * state (i.e., STANDBY).
- *
- * To do this, run YieldingJob in an IO thread, get it into the READY
- * state, then have a drained section.  Before ending the section,
- * acquire the context so the job will not be entered and will thus
- * remain on STANDBY.
- *
- * job_complete_locked() should still work without error.
- *
- * Note that on the QMP interface, it is impossible to lock an IO
- * thread before a drained section ends.  In practice, the
- * bdrv_drain_all_end() and the aio_context_acquire() will be
- * reversed.  However, that makes for worse reproducibility here:
- * Sometimes, the job would no longer be in STANDBY then but already
- * be started.  We cannot prevent that, because the IO thread runs
- * concurrently.  We can only prevent it by taking the lock before
- * ending the drained section, so we do that.
- *
- * (You can reverse the order of operations and most of the time the
- * test will pass, but sometimes the assert(status == STANDBY) will
- * fail.)
- */
-static void test_complete_in_standby(void)
-{
-    BlockBackend *blk;
-    IOThread *iothread;
-    AioContext *ctx;
-    Job *job;
-    BlockJob *bjob;
-
-    /* Create a test drive, move it to an IO thread */
-    blk = create_blk(NULL);
-    iothread = iothread_new();
-
-    ctx = iothread_get_aio_context(iothread);
-    blk_set_aio_context(blk, ctx, &error_abort);
-
-    /* Create our test job */
-    bjob = mk_job(blk, "job", &test_yielding_driver, true,
-                  JOB_MANUAL_FINALIZE | JOB_MANUAL_DISMISS);
-    job = &bjob->job;
-    assert_job_status_is(job, JOB_STATUS_CREATED);
-
-    /* Wait for the job to become READY */
-    job_start(job);
-    /*
-     * Here we are waiting for the status to change, so don't bother
-     * protecting the read every time.
-     */
-    AIO_WAIT_WHILE_UNLOCKED(ctx, job->status != JOB_STATUS_READY);
-
-    /* Begin the drained section, pausing the job */
-    bdrv_drain_all_begin();
-    assert_job_status_is(job, JOB_STATUS_STANDBY);
-
-    /* Lock the IO thread to prevent the job from being run */
-    aio_context_acquire(ctx);
-    /* This will schedule the job to resume it */
-    bdrv_drain_all_end();
-    aio_context_release(ctx);
-
-    WITH_JOB_LOCK_GUARD() {
-        /* But the job cannot run, so it will remain on standby */
-        assert(job->status == JOB_STATUS_STANDBY);
-
-        /* Even though the job is on standby, this should work */
-        job_complete_locked(job, &error_abort);
-
-        /* The test is done now, clean up. */
-        job_finish_sync_locked(job, NULL, &error_abort);
-        assert(job->status == JOB_STATUS_PENDING);
-
-        job_finalize_locked(job, &error_abort);
-        assert(job->status == JOB_STATUS_CONCLUDED);
-
-        job_dismiss_locked(&job, &error_abort);
-    }
-
-    aio_context_acquire(ctx);
-    destroy_blk(blk);
-    aio_context_release(ctx);
-    iothread_join(iothread);
-}
-
 int main(int argc, char **argv)
 {
     qemu_init_main_loop(&error_abort);
@@ -531,13 +402,5 @@ int main(int argc, char **argv)
     g_test_add_func("/blockjob/cancel/standby", test_cancel_standby);
     g_test_add_func("/blockjob/cancel/pending", test_cancel_pending);
     g_test_add_func("/blockjob/cancel/concluded", test_cancel_concluded);
-
-    /*
-     * This test is flaky and sometimes fails in CI and otherwise:
-     * don't run unless user opts in via environment variable.
-     */
-    if (getenv("QEMU_TEST_FLAKY_TESTS")) {
-        g_test_add_func("/blockjob/complete_in_standby", test_complete_in_standby);
-    }
     return g_test_run();
 }

tests/unit/test-replication.c

@@ -199,17 +199,13 @@ static BlockBackend *start_primary(void)
 static void teardown_primary(void)
 {
     BlockBackend *blk;
-    AioContext *ctx;
 
     /* remove P_ID */
     blk = blk_by_name(P_ID);
     assert(blk);
 
-    ctx = blk_get_aio_context(blk);
-    aio_context_acquire(ctx);
     monitor_remove_blk(blk);
     blk_unref(blk);
-    aio_context_release(ctx);
 }
 
 static void test_primary_read(void)
@@ -345,27 +341,20 @@ static void teardown_secondary(void)
 {
     /* only need to destroy two BBs */
     BlockBackend *blk;
-    AioContext *ctx;
 
     /* remove S_LOCAL_DISK_ID */
     blk = blk_by_name(S_LOCAL_DISK_ID);
     assert(blk);
 
-    ctx = blk_get_aio_context(blk);
-    aio_context_acquire(ctx);
     monitor_remove_blk(blk);
     blk_unref(blk);
-    aio_context_release(ctx);
 
     /* remove S_ID */
     blk = blk_by_name(S_ID);
     assert(blk);
 
-    ctx = blk_get_aio_context(blk);
-    aio_context_acquire(ctx);
     monitor_remove_blk(blk);
     blk_unref(blk);
-    aio_context_release(ctx);
 }
 
 static void test_secondary_read(void)

util/async.c

@@ -562,12 +562,10 @@ static void co_schedule_bh_cb(void *opaque)
         Coroutine *co = QSLIST_FIRST(&straight);
         QSLIST_REMOVE_HEAD(&straight, co_scheduled_next);
         trace_aio_co_schedule_bh_cb(ctx, co);
-        aio_context_acquire(ctx);
 
         /* Protected by write barrier in qemu_aio_coroutine_enter */
         qatomic_set(&co->scheduled, NULL);
         qemu_aio_coroutine_enter(ctx, co);
-        aio_context_release(ctx);
     }
 }
 
@@ -707,9 +705,7 @@ void aio_co_enter(AioContext *ctx, Coroutine *co)
         assert(self != co);
         QSIMPLEQ_INSERT_TAIL(&self->co_queue_wakeup, co, co_queue_next);
     } else {
-        aio_context_acquire(ctx);
         qemu_aio_coroutine_enter(ctx, co);
-        aio_context_release(ctx);
     }
 }
 

util/vhost-user-server.c

@@ -360,10 +360,7 @@ static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
 
     qio_channel_set_follow_coroutine_ctx(server->ioc, true);
 
-    /* Attaching the AioContext starts the vu_client_trip coroutine */
-    aio_context_acquire(server->ctx);
     vhost_user_server_attach_aio_context(server, server->ctx);
-    aio_context_release(server->ctx);
 }
 
 /* server->ctx acquired by caller */