Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging

Block layer patches

- Fix blockdev-create with iothreads
- Remove aio_disable_external() API

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# gpg:                using RSA key DC3DEB159A9AF95D3D7456FE7F09B272C88F2FD6
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# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]

* tag 'for-upstream' of https://repo.or.cz/qemu/kevin: (32 commits)
  aio: remove aio_disable_external() API
  virtio: do not set is_external=true on host notifiers
  virtio-scsi: implement BlockDevOps->drained_begin()
  virtio-blk: implement BlockDevOps->drained_begin()
  virtio: make it possible to detach host notifier from any thread
  block/fuse: do not set is_external=true on FUSE fd
  block/export: don't require AioContext lock around blk_exp_ref/unref()
  block/export: rewrite vduse-blk drain code
  hw/xen: do not set is_external=true on evtchn fds
  xen-block: implement BlockDevOps->drained_begin()
  block: drain from main loop thread in bdrv_co_yield_to_drain()
  block: add blk_in_drain() API
  hw/xen: do not use aio_set_fd_handler(is_external=true) in xen_xenstore
  block/export: stop using is_external in vhost-user-blk server
  block/export: wait for vhost-user-blk requests when draining
  util/vhost-user-server: rename refcount to in_flight counter
  virtio-scsi: stop using aio_disable_external() during unplug
  virtio-scsi: avoid race between unplug and transport event
  hw/qdev: introduce qdev_is_realized() helper
  block-backend: split blk_do_set_aio_context()
  ...

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 31 insertions, 15 deletions

diff --git a/block.c b/block.c
index a2f8d5a0c0..dae629075c 100644
--- a/block.c
+++ b/block.c
@@ -1613,6 +1613,7 @@ 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();
@@ -1660,15 +1661,21 @@ 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);
@@ -3478,6 +3485,8 @@ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
  * itself, all options starting with "${bdref_key}." are considered part of the
  * BlockdevRef.
  *
+ * The caller must hold the main AioContext lock.
+ *
  * TODO Can this be unified with bdrv_open_image()?
  */
 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
@@ -3644,6 +3653,9 @@ done:
  * BlockdevRef.
  *
  * The BlockdevRef will be removed from the options QDict.
+ *
+ * @parent can move to a different AioContext in this function. Callers must
+ * make sure that their AioContext locking is still correct after this.
  */
 BdrvChild *bdrv_open_child(const char *filename,
                            QDict *options, const char *bdref_key,
@@ -3668,6 +3680,9 @@ BdrvChild *bdrv_open_child(const char *filename,
 
 /*
  * Wrapper on bdrv_open_child() for most popular case: open primary child of bs.
+ *
+ * @parent can move to a different AioContext in this function. Callers must
+ * make sure that their AioContext locking is still correct after this.
  */
 int bdrv_open_file_child(const char *filename,
                          QDict *options, const char *bdref_key,
@@ -3810,9 +3825,7 @@ out:
  * should be opened. If specified, neither options nor a filename may be given,
  * nor can an existing BDS be reused (that is, *pbs has to be NULL).
  *
- * The caller must always hold @filename AioContext lock, because this
- * function eventually calls bdrv_refresh_total_sectors() which polls
- * when called from non-coroutine context.
+ * The caller must always hold the main AioContext lock.
  */
 static BlockDriverState * no_coroutine_fn
 bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
@@ -4100,11 +4113,7 @@ close_and_fail:
     return NULL;
 }
 
-/*
- * The caller must always hold @filename AioContext lock, because this
- * function eventually calls bdrv_refresh_total_sectors() which polls
- * when called from non-coroutine context.
- */
+/* The caller must always hold the main AioContext lock. */
 BlockDriverState *bdrv_open(const char *filename, const char *reference,
                             QDict *options, int flags, Error **errp)
 {
@@ -5390,12 +5399,17 @@ static void bdrv_delete(BlockDriverState *bs)
  * empty set of options. The reference to the QDict belongs to the block layer
  * after the call (even on failure), so if the caller intends to reuse the
  * dictionary, it needs to use qobject_ref() before calling bdrv_open.
+ *
+ * The caller holds the AioContext lock for @bs. It must make sure that @bs
+ * stays in the same AioContext, i.e. @options must not refer to nodes in a
+ * different AioContext.
  */
 BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *options,
                                    int flags, Error **errp)
 {
     ERRP_GUARD();
     int ret;
+    AioContext *ctx = bdrv_get_aio_context(bs);
     BlockDriverState *new_node_bs = NULL;
     const char *drvname, *node_name;
     BlockDriver *drv;
@@ -5416,8 +5430,14 @@ 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 */
     if (!new_node_bs) {
         error_prepend(errp, "Could not create node: ");
@@ -7043,6 +7063,8 @@ 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);
@@ -7192,6 +7214,7 @@ 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)
@@ -7282,9 +7305,6 @@ static void bdrv_detach_aio_context(BlockDriverState *bs)
         bs->drv->bdrv_detach_aio_context(bs);
     }
 
-    if (bs->quiesce_counter) {
-        aio_enable_external(bs->aio_context);
-    }
     bs->aio_context = NULL;
 }
 
@@ -7294,10 +7314,6 @@ static void bdrv_attach_aio_context(BlockDriverState *bs,
     BdrvAioNotifier *ban, *ban_tmp;
     GLOBAL_STATE_CODE();
 
-    if (bs->quiesce_counter) {
-        aio_disable_external(new_context);
-    }
-
     bs->aio_context = new_context;
 
     if (bs->drv && bs->drv->bdrv_attach_aio_context) {