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[Qemu-block] [RFC PATCH 00/11] Block layer thread-safety, part 2

From: Paolo Bonzini
Subject: [Qemu-block] [RFC PATCH 00/11] Block layer thread-safety, part 2
Date: Wed, 31 May 2017 11:43:19 +0200

This part takes care of drivers and devices, making sure that they can
accept concurrent I/O from multiple AioContext.  Only RFC for now because it
depends on Kevin's QED conversion to coroutines, which is still in flux.

The following drivers are thread-safe without using any QemuMutex/CoMutex:
crypto, gluster, null, rbd, win32-aio.

The following drivers already use mutexes for everything except possibly
snapshots, which do not (yet?) need protection: bochs, cloop, dmg, qcow,
parallels, vhdx, vmdk, curl, iscsi, nfs.

The following drivers already use mutexes for _almost_ everything: vpc
(missing get_block_status), vdi (missing bitmap access), vvfat (missing
commit), nbd (s->in_flight not protected), qcow2 (must call CoQueue APIs
under CoMutex).  They are fixed by patches 1-6.

The following drivers must be changed to use CoMutex to protect internal
data: qed (patches 7-9), sheepdog (patch 10).

The following driver must be changed to support I/O from any AioContext:
ssh.  It is fixed by patch 11.


Paolo Bonzini (11):
  qcow2: call CoQueue APIs under CoMutex
  coroutine-lock: add qemu_co_rwlock_downgrade and qemu_co_rwlock_upgrade
  vdi: make it thread-safe
  vpc: make it thread-safe
  vvfat: make it thread-safe
  nbd: make it thread-safe
  qed: move tail of qed_aio_write_main to qed_aio_write_{cow,alloc}
  block: invoke .bdrv_drain callback in coroutine context and from AioContext
  qed: protect table cache with CoMutex
  sheepdog: add queue_lock
  ssh: support I/O from any AioContext

 block/io.c                 |  42 +++++++---
 block/nbd-client.c         |  30 +++----
 block/qcow2.c              |   4 +-
 block/qed-cluster.c        |   4 +-
 block/qed-l2-cache.c       |   6 ++
 block/qed-table.c          |  24 ++++--
 block/qed.c                | 195 +++++++++++++++++++++++++++------------------
 block/qed.h                |  11 ++-
 block/sheepdog.c           |  21 ++++-
 block/ssh.c                |  24 ++++--
 block/vdi.c                |  48 +++++------
 block/vpc.c                |  20 ++---
 block/vvfat.c              |   8 +-
 include/block/block_int.h  |   2 +-
 include/qemu/coroutine.h   |  19 +++++
 util/qemu-coroutine-lock.c |  35 ++++++++
 16 files changed, 326 insertions(+), 167 deletions(-)


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