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

[Paolo Bonzini]

On 08/06/2017 14:52, Stefan Hajnoczi wrote:
> On Wed, May 31, 2017 at 11:43:19AM +0200, Paolo Bonzini wrote:
>> 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
>>
>> 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(-)
>>
>> -- 
>> 2.13.0
> 
> Reviewed-by: Stefan Hajnoczi <address@hidden>

Thanks, I'll repost once QED is converted to coroutines, and send part 3
when I have some time.

Paolo