Chunk server: implement re-lock handling in write appender, by queueing the current op into "pending submit" queue, and run the pending submit queue from the first thread that re-acquires the mutex first. Re-use the pending ops queue to implement pending submit queue, by storing the pending submit queue position of the first pending op.
Chunk server: implement re-lock handling in write appender, by queueing the current op into "pending submit" queue, and run the pending submit queue from the first thread that re-acquires the mutex first. Re-use the pending ops queue to implement pending submit queue, by storing the pending submit queue position of the first pending op.

thebigbrain/qfs,qnu/qfs,qnu/qfs,quantcast/qfs,qnu/qfs,fengshao0907/qfs,quantcast/qfs,quantcast/qfs,fengshao0907/qfs,fengshao0907/qfs,chanwit/qfs,chanwit/qfs,thebigbrain/qfs,fengshao0907/qfs,quantcast/qfs,chanwit/qfs,thebigbrain/qfs,chanwit/qfs,qnu/qfs,qnu/qfs,quantcast/qfs,qnu/qfs,quantcast/qfs,fengshao0907/qfs,chanwit/qfs,quantcast/qfs,chanwit/qfs,thebigbrain/qfs,fengshao0907/qfs,fengshao0907/qfs,thebigbrain/qfs,chanwit/qfs,thebigbrain/qfs,fengshao0907/qfs,thebigbrain/qfs,thebigbrain/qfs,qnu/qfs,quantcast/qfs,chanwit/qfs,qnu/qfs