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Date: Wed, 06 May 2015 16:22:54 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [RFC PATCH 3/7] block: Add op blocker notifier list
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To: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, jcody@redhat.com, armbru@redhat.com, mreitz@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>



On 06/05/2015 13:23, Fam Zheng wrote:
>  void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
>  {
>      BdrvOpBlocker *blocker;
>      assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
>  
> +    bdrv_op_blocker_notify(bs, op, reason, true);
>      blocker = g_new0(BdrvOpBlocker, 1);
>      blocker->reason = reason;
>      QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
> @@ -3405,6 +3424,7 @@ void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
>  {
>      BdrvOpBlocker *blocker, *next;
>      assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
> +    bdrv_op_blocker_notify(bs, op, reason, false);
>      QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
>          if (blocker->reason == reason) {
>              QLIST_REMOVE(blocker, list);

Changed in the following patch.

Also, should we only invoke the notifier if the list becomes
empty/non-empty?  Is there any reason why the notifier would like to
know the particular Error that was added?

Paolo