[Qemu-devel] [PATCH v2 1/3] block: block: introduce bdrv_io_plug() and bdrv_io_unplug()

[Ming Lei <ming.lei@canonical.com>]

This patch introduces these two APIs so that following
patches can support queuing I/O requests and submitting them
at batch for improving I/O performance.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
 block.c                   |   21 +++++++++++++++++++++
 include/block/block.h     |    3 +++
 include/block/block_int.h |    4 ++++
 3 files changed, 28 insertions(+)

diff --git a/block.c b/block.c
index 217f523..fea9e43 100644
--- a/block.c
+++ b/block.c
@@ -1910,6 +1910,7 @@ void bdrv_drain_all(void)
             bool bs_busy;
 
             aio_context_acquire(aio_context);
+            bdrv_io_unplug(bs);
             bdrv_start_throttled_reqs(bs);
             bs_busy = bdrv_requests_pending(bs);
             bs_busy |= aio_poll(aio_context, bs_busy);
@@ -5774,3 +5775,23 @@ bool bdrv_is_first_non_filter(BlockDriverState *candidate)
 
     return false;
 }
+
+void bdrv_io_plug(BlockDriverState *bs)
+{
+    BlockDriver *drv = bs->drv;
+    if (drv && drv->bdrv_io_plug) {
+        drv->bdrv_io_plug(bs);
+    } else if (bs->file) {
+        bdrv_io_plug(bs->file);
+    }
+}
+
+void bdrv_io_unplug(BlockDriverState *bs)
+{
+    BlockDriver *drv = bs->drv;
+    if (drv && drv->bdrv_io_unplug) {
+        drv->bdrv_io_unplug(bs);
+    } else if (bs->file) {
+        bdrv_io_unplug(bs->file);
+    }
+}
diff --git a/include/block/block.h b/include/block/block.h
index d0baf4f..ea627d2 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -578,4 +578,7 @@ AioContext *bdrv_get_aio_context(BlockDriverState *bs);
  */
 void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context);
 
+void bdrv_io_plug(BlockDriverState *bs);
+void bdrv_io_unplug(BlockDriverState *bs);
+
 #endif
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 715c761..0d75ca6 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -257,6 +257,10 @@ struct BlockDriver {
     void (*bdrv_attach_aio_context)(BlockDriverState *bs,
                                     AioContext *new_context);
 
+    /* io queue for linux-aio */
+    void (*bdrv_io_plug)(BlockDriverState *bs);
+    void (*bdrv_io_unplug)(BlockDriverState *bs);
+
     QLIST_ENTRY(BlockDriver) list;
 };
 
-- 
1.7.9.5