raw-posix: Switch to bdrv_co_* interfaces

In order to use the modern byte-based .bdrv_co_preadv/pwritev()
interface, this patch switches raw-posix to coroutine-based interfaces
as a first step. In terms of semantics and performance, it doesn't make
a difference with the existing code whether we go from a coroutine to a
callback-based interface already in block/io.c or only in linux-aio.c

As there have been concerns in the past that this change may be a step
in the wrong direction with respect to a possible AIO fast path, the
old callback-based interface for linux-aio is left around and can be
reactivated when a fast path (e.g. directly from virtio-blk dataplane,
bypassing the whole block layer) is implemented.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/block/raw-aio.h b/block/raw-aio.h
index 714714e016..03bbfba565 100644
--- a/block/raw-aio.h
+++ b/block/raw-aio.h
@@ -15,6 +15,7 @@
 #ifndef QEMU_RAW_AIO_H
 #define QEMU_RAW_AIO_H
 
+#include "qemu/coroutine.h"
 #include "qemu/iov.h"
 
 /* AIO request types */
@@ -38,6 +39,9 @@
 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,
+                                int64_t sector_num, QEMUIOVector *qiov,
+                                int nb_sectors, 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);