[PATCH V5 0/4] blk-mq: implement queue quiesce via percpu_ref for BLK_MQ_F_BLOCKING

[Sagi Grimberg]

>> Hi Jens,
>>
>> The 1st patch add .mq_quiesce_mutex for serializing quiesce/unquiesce,
>> and prepares for replacing srcu with percpu_ref.
>>
>> The 2nd patch replaces srcu with percpu_ref.
>>
>> The 3rd patch adds tagset quiesce interface.
>>
>> The 4th patch applies tagset quiesce interface for NVMe subsystem.
> 
> What is this series against?

It didn't apply cleanly to me too until I realized it is
on top of v4 of: "percpu_ref & block: reduce memory footprint of 
percpu_ref in fast path"