[Qemu-block] [PATCH 11/18] aio: introduce qemu_get_current_aio_context

[Paolo Bonzini]

This will be used by bdrv_poll_while (and thus by bdrv_drain)
to choose how to wait for I/O completion.

Reviewed-by: Fam Zheng <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
 include/block/aio.h | 15 +++++++++++++++
 iothread.c          |  9 +++++++++
 stubs/Makefile.objs |  1 +
 stubs/iothread.c    |  8 ++++++++
 4 files changed, 33 insertions(+)
 create mode 100644 stubs/iothread.c

diff --git a/include/block/aio.h b/include/block/aio.h
index b9fe2cb..60a4f21 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -453,6 +453,21 @@ static inline bool aio_node_check(AioContext *ctx, bool 
is_external)
 }
 
 /**
+ * Return the AioContext whose event loop runs in the current I/O thread.
+ */
+AioContext *qemu_get_current_aio_context(void);
+
+/**
+ * @ctx: the aio context
+ *
+ * Return whether we are running in the I/O thread that manages @ctx.
+ */
+static inline bool aio_context_in_iothread(AioContext *ctx)
+{
+    return ctx == qemu_get_current_aio_context();
+}
+
+/**
  * aio_context_setup:
  * @ctx: the aio context
  *
diff --git a/iothread.c b/iothread.c
index fbeb8de..62c8796 100644
--- a/iothread.c
+++ b/iothread.c
@@ -20,6 +20,7 @@
 #include "qmp-commands.h"
 #include "qemu/error-report.h"
 #include "qemu/rcu.h"
+#include "qemu/main-loop.h"
 
 typedef ObjectClass IOThreadClass;
 
@@ -28,6 +29,13 @@ typedef ObjectClass IOThreadClass;
 #define IOTHREAD_CLASS(klass) \
    OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
 
+static __thread IOThread *my_iothread;
+
+AioContext *qemu_get_current_aio_context(void)
+{
+    return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
+}
+
 static void *iothread_run(void *opaque)
 {
     IOThread *iothread = opaque;
@@ -35,6 +43,7 @@ static void *iothread_run(void *opaque)
 
     rcu_register_thread();
 
+    my_iothread = iothread;
     qemu_mutex_lock(&iothread->init_done_lock);
     iothread->thread_id = qemu_get_thread_id();
     qemu_cond_signal(&iothread->init_done_cond);
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index c5850e8..84b9d9e 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -17,6 +17,7 @@ stub-obj-y += gdbstub.o
 stub-obj-y += get-fd.o
 stub-obj-y += get-next-serial.o
 stub-obj-y += get-vm-name.o
+stub-obj-y += iothread.o
 stub-obj-y += iothread-lock.o
 stub-obj-y += is-daemonized.o
 stub-obj-y += machine-init-done.o
diff --git a/stubs/iothread.c b/stubs/iothread.c
new file mode 100644
index 0000000..8cc9e28
--- /dev/null
+++ b/stubs/iothread.c
@@ -0,0 +1,8 @@
+#include "qemu/osdep.h"
+#include "block/aio.h"
+#include "qemu/main-loop.h"
+
+AioContext *qemu_get_current_aio_context(void)
+{
+    return qemu_get_aio_context();
+}
-- 
2.7.4