linux-aio: share one LinuxAioState within an AioContext

This has better performance because it executes fewer system calls
and does not use a bottom half per disk.

Originally proposed by Ming Lei.

[Changed #include "raw-aio.h" to "block/raw-aio.h" in win32-aio.c to fix
build error as reported by Peter Maydell <peter.maydell@linaro.org>.
--Stefan]

Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1467650000-51385-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

squash! linux-aio: share one LinuxAioState within an AioContext

include/block/aio.h

@@ -47,6 +47,9 @@ typedef struct AioHandler AioHandler;
 typedef void QEMUBHFunc(void *opaque);
 typedef void IOHandler(void *opaque);
 
+struct ThreadPool;
+struct LinuxAioState;
+
 struct AioContext {
     GSource source;
 
@@ -119,6 +122,13 @@ struct AioContext {
     /* Thread pool for performing work and receiving completion callbacks */
     struct ThreadPool *thread_pool;
 
+#ifdef CONFIG_LINUX_AIO
+    /* State for native Linux AIO.  Uses aio_context_acquire/release for
+     * locking.
+     */
+    struct LinuxAioState *linux_aio;
+#endif
+
     /* TimerLists for calling timers - one per clock type */
     QEMUTimerListGroup tlg;
 
@@ -335,6 +345,9 @@ GSource *aio_get_g_source(AioContext *ctx);
 /* Return the ThreadPool bound to this AioContext */
 struct ThreadPool *aio_get_thread_pool(AioContext *ctx);
 
+/* Return the LinuxAioState bound to this AioContext */
+struct LinuxAioState *aio_get_linux_aio(AioContext *ctx);
+
 /**
  * aio_timer_new:
  * @ctx: the aio context

include/block/raw-aio.h

@@ -0,0 +1,68 @@
+/*
+ * Declarations for AIO in the raw protocol
+ *
+ * Copyright IBM, Corp. 2008
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
+ */
+#ifndef QEMU_RAW_AIO_H
+#define QEMU_RAW_AIO_H
+
+#include "qemu/coroutine.h"
+#include "qemu/iov.h"
+
+/* AIO request types */
+#define QEMU_AIO_READ         0x0001
+#define QEMU_AIO_WRITE        0x0002
+#define QEMU_AIO_IOCTL        0x0004
+#define QEMU_AIO_FLUSH        0x0008
+#define QEMU_AIO_DISCARD      0x0010
+#define QEMU_AIO_WRITE_ZEROES 0x0020
+#define QEMU_AIO_TYPE_MASK \
+        (QEMU_AIO_READ|QEMU_AIO_WRITE|QEMU_AIO_IOCTL|QEMU_AIO_FLUSH| \
+         QEMU_AIO_DISCARD|QEMU_AIO_WRITE_ZEROES)
+
+/* AIO flags */
+#define QEMU_AIO_MISALIGNED   0x1000
+#define QEMU_AIO_BLKDEV       0x2000
+
+
+/* linux-aio.c - Linux native implementation */
+#ifdef CONFIG_LINUX_AIO
+typedef struct LinuxAioState LinuxAioState;
+LinuxAioState *laio_init(void);
+void laio_cleanup(LinuxAioState *s);
+int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
+                                uint64_t offset, QEMUIOVector *qiov, int type);
+BlockAIOCB *laio_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
+        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+        BlockCompletionFunc *cb, void *opaque, int type);
+void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context);
+void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context);
+void laio_io_plug(BlockDriverState *bs, LinuxAioState *s);
+void laio_io_unplug(BlockDriverState *bs, LinuxAioState *s);
+#endif
+
+#ifdef _WIN32
+typedef struct QEMUWin32AIOState QEMUWin32AIOState;
+QEMUWin32AIOState *win32_aio_init(void);
+void win32_aio_cleanup(QEMUWin32AIOState *aio);
+int win32_aio_attach(QEMUWin32AIOState *aio, HANDLE hfile);
+BlockAIOCB *win32_aio_submit(BlockDriverState *bs,
+        QEMUWin32AIOState *aio, HANDLE hfile,
+        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+        BlockCompletionFunc *cb, void *opaque, int type);
+void win32_aio_detach_aio_context(QEMUWin32AIOState *aio,
+                                  AioContext *old_context);
+void win32_aio_attach_aio_context(QEMUWin32AIOState *aio,
+                                  AioContext *new_context);
+#endif
+
+#endif /* QEMU_RAW_AIO_H */