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Date: Tue, 26 Nov 2013 10:07:30 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v4 2/7] block: Introduce op_blockers to
	BlockDriverState
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kwolf@redhat.com, hbrock@redhat.com, qemu-devel@nongnu.org, rjones@redhat.com, imain@redhat.com, stefanha@redhat.com

On 2013=E5=B9=B411=E6=9C=8826=E6=97=A5 01:13, Paolo Bonzini wrote:
> Il 22/11/2013 06:24, Fam Zheng ha scritto:
>> +void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reaso=
n)
>> +{
>> +    BdrvOpBlocker *blocker;
>> +    assert(op >=3D0 && op < BLOCK_OP_TYPE_MAX);
>> +
>> +    blocker =3D g_malloc0(sizeof(BdrvOpBlocker));
>> +    blocker->reason =3D reason;
>> +    QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
>> +}
>> +
>> +void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *rea=
son)
>
> What about making BlockOpType a bitmask, and having bdrv_op_{,un}block
> take multiple ORed BlockOpTypes?
>
> bdrv_op_{,un}block_all then are not necessary, you only need a
> BLOCK_OPERATION_ALL value.
>

Bitmap is not enough, at least it should be an array. For example when=20
we enable multiple block jobs, there're two stoppers for drive_del, right=
?

And a bool or int is not as friendly as an error message, because when=20
an operation is blocked we can't print a specific reason when we don't=20
have this information at all. So let's be consistent with migration=20
blockers.

Fam