Re: [Qemu-devel] [PATCH v3 0/4] fix image fleecing

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

06.07.2018 10:17, Fam Zheng wrote:
> On Thu, 07/05 10:46, Vladimir Sementsov-Ogievskiy wrote:
>> Hi all.
>>
>> This fixes image fleecing scheme for 3.0, details are in 04 patch.
> Looks like this breaks 'test-replication':
>
> http://patchew.org/QEMU/20180705074638.770905-1-vsementsov@virtuozzo.com/
>
> test-replication: /stor/work/qemu/block/io.c:725: wait_serialising_requests: Assertion `qemu_coroutine_self() != req->co' failed.
> GTester: last random seed: R02Se49967625f19c5be9918a2503fb2fff5
> test-replication: /stor/work/qemu/block/io.c:725: wait_serialising_requests: Assertion `qemu_coroutine_self() != req->co' failed.
>    GTESTER tests/test-qht-par
> GTester: last random seed: R02S8fad2bb2daddc51eb51623bb7c86cb67
> test-replication: /stor/work/qemu/block/io.c:725: wait_serialising_requests: Assertion `qemu_coroutine_self() != req->co' failed.
> GTester: last random seed: R02S024718e9b1e2b1facafe254c43e1430b
>
> Fam

interesting.

in gdb I see, that both requests are identical (i.e. their 
BdrvTrackedRequeststructs, except list filed)writes (self and req)...

and it's actually the same request, duplicated in the ist, first it is 
created in bdrv_co_copy_range_internal,

and than again,
#0  tracked_request_begin (req=0x7fffe8f9e7d0, bs=0x555555a43040, 
offset=33554432, bytes=33554432, type=
     BDRV_TRACKED_WRITE) at block/io.c:598
#1  0x00005555555f76bc in bdrv_co_copy_range_internal 
(src=0x55555597ef80, src_offset=33882112,
     dst=0x5555559f1d30, dst_offset=33554432, bytes=33554432, 
read_flags=BDRV_REQ_NO_SERIALISING,
     write_flags=BDRV_REQ_SERIALISING, recurse_src=true) at block/io.c:2949
#2  0x00005555555f78e9 in bdrv_co_copy_range_from (src=0x55555597ef80, 
src_offset=33882112,
     dst=0x5555559f1d30, dst_offset=33554432, bytes=33554432, 
read_flags=BDRV_REQ_NO_SERIALISING,
     write_flags=BDRV_REQ_SERIALISING) at block/io.c:2995
#3  0x00005555555ae931 in qcow2_co_copy_range_from (bs=0x555555977ff0, 
src=0x5555559f14d0,
     src_offset=33554432, dst=0x5555559f1d30, dst_offset=33554432, 
bytes=33554432,
     read_flags=BDRV_REQ_NO_SERIALISING, 
write_flags=BDRV_REQ_SERIALISING) at block/qcow2.c:3311
#4  0x00005555555f77cf in bdrv_co_copy_range_internal 
(src=0x5555559f14d0, src_offset=33554432,
     dst=0x5555559f1d30, dst_offset=33554432, bytes=33554432, 
read_flags=BDRV_REQ_NO_SERIALISING,
     write_flags=BDRV_REQ_SERIALISING, recurse_src=true) at block/io.c:2966


so, it's actually bug in copy_range architecture.

-- 
Best regards,
Vladimir