Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2021-02-12' into staging

nbd patches for 2021-02-12

- let qemu-nbd handle larger backlog of connecting clients
- fix a few NBD-related iotest failures
- add block cancellation hook for faster response to NBD failures

# gpg: Signature made Fri 12 Feb 2021 19:57:56 GMT
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
# gpg:                 aka "[jpeg image of size 6874]" [full]
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-nbd-2021-02-12:
  iotests/264: add backup-cancel test-case
  block/backup: implement .cancel job handler
  iotests/264: add mirror-cancel test-case
  iotests.py: qemu_nbd_popen: remove pid file after use
  iotests/264: move to python unittest
  block/mirror: implement .cancel job handler
  job: add .cancel handler for the driver
  block/raw-format: implement .bdrv_cancel_in_flight handler
  block/nbd: implement .bdrv_cancel_in_flight
  block: add new BlockDriver handler: bdrv_cancel_in_flight
  io: error_prepend() in qio_channel_readv_full_all() causes segfault
  iotests/210: Fix reference output
  qemu-nbd: Permit --shared=0 for unlimited clients
  qemu-nbd: Use SOMAXCONN for socket listen() backlog

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 17 insertions, 0 deletions

diff --git a/include/block/block.h b/include/block/block.h
index 0a9f2c187c..2f2698074e 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -849,4 +849,7 @@ int coroutine_fn bdrv_co_copy_range(BdrvChild *src, int64_t src_offset,
                                     BdrvChild *dst, int64_t dst_offset,
                                     int64_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 22a2789d35..88e4111939 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -353,6 +353,15 @@ struct BlockDriver {
         int64_t *map, BlockDriverState **file);
 
     /*
+     * This informs the driver that we are no longer interested in the result
+     * of in-flight requests, so don't waste the time if possible.
+     *
+     * One example usage is to avoid waiting for an nbd target node reconnect
+     * timeout during job-cancel.
+     */
+    void (*bdrv_cancel_in_flight)(BlockDriverState *bs);
+
+    /*
      * Invalidate any cached meta-data.
      */
     void coroutine_fn (*bdrv_co_invalidate_cache)(BlockDriverState *bs,
diff --git a/include/qemu/job.h b/include/qemu/job.h
index 32aabb1c60..efc6fa7544 100644
--- a/include/qemu/job.h
+++ b/include/qemu/job.h
@@ -251,6 +251,11 @@ struct JobDriver {
      */
     void (*clean)(Job *job);
 
+    /**
+     * If the callback is not NULL, it will be invoked in job_cancel_async
+     */
+    void (*cancel)(Job *job);
+
 
     /** Called when the job is freed */
     void (*free)(Job *job);