[PATCH 01/11] block: add new BlockDriver handler: bdrv_cancel_in_flight

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

It will be used to stop retrying NBD requests on mirror cancel.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/block/block.h     |  3 +++
 include/block/block_int.h |  9 +++++++++
 block/io.c                | 11 +++++++++++
 3 files changed, 23 insertions(+)

diff --git a/include/block/block.h b/include/block/block.h
index c9d7c58765..3990ee3677 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -836,4 +836,7 @@ int coroutine_fn bdrv_co_copy_range(BdrvChild *src, uint64_t src_offset,
                                     BdrvChild *dst, uint64_t dst_offset,
                                     uint64_t bytes, BdrvRequestFlags read_flags,
                                     BdrvRequestFlags write_flags);
+
+void bdrv_cancel_in_flight(BlockDriverState *bs);
+
 #endif
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 95d9333be1..07a87ce5e7 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -344,6 +344,15 @@ struct BlockDriver {
         bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum,
         int64_t *map, BlockDriverState **file);
 
+    /*
+     * This informs the driver that we are not more interested in in-flight
+     * requests results, so don't waste the time if possible.
+     *
+     * The example usage is to not wait for nbd target nodedreconnect timeout on
+     * job-cancel.
+     */
+    void (*bdrv_cancel_in_flight)(BlockDriverState *bs);
+
     /*
      * Invalidate any cached meta-data.
      */
diff --git a/block/io.c b/block/io.c
index ec5e152bb7..5dcb6433f9 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3288,3 +3288,14 @@ out:
 
     return ret;
 }
+
+void bdrv_cancel_in_flight(BlockDriverState *bs)
+{
+    if (!bs || !bs->drv) {
+        return;
+    }
+
+    if (bs->drv->bdrv_cancel_in_flight) {
+        bs->drv->bdrv_cancel_in_flight(bs);
+    }
+}
-- 
2.21.3