[PATCH 0/4] blk-mq: allow to unfreeze queue when io isn't drained

[Ming Lei]

Hi,

The 1st patch is one cleanup and prepares for introducing percpu_ref_resurge().

The 2nd patch introduces percpu_ref_resurge() for implementing
blk_mq_unfreeze_queue_no_drain_io().

The 3rd patch introdces blk_mq_unfreeze_queue_no_drain_io() for
cases in which queue can be unfreeze without draininig IO.

The 4th patch applies blk_mq_unfreeze_queue_no_drain_io() to
NVMe PCI timeout, so that IO hang may be avoided inside
nvme_reset_work() when new IO timeout is triggered. 

Part of idea is from Jianchao's early work:

https://marc.info/?l=linux-kernel&m=153612052611020&w=2


Ming Lei (4):
  percpu-refcount: move zeroing of percpu part into
    percpu_ref_switch_to_atomic_rcu
  lib/percpu-refcount: introduce percpu_ref_resurge()
  blk-mq: introduce blk_mq_unfreeze_queue_no_drain_io
  nvme: don't drain IO in nvme_reset_work()

 block/blk-mq.c                  | 25 +++++++++++++--
 drivers/nvme/host/core.c        | 12 ++++---
 drivers/nvme/host/nvme.h        |  2 +-
 drivers/nvme/host/pci.c         |  3 +-
 include/linux/blk-mq.h          |  1 +
 include/linux/percpu-refcount.h |  1 +
 lib/percpu-refcount.c           | 71 +++++++++++++++++++++++++++++++----------
 7 files changed, 90 insertions(+), 25 deletions(-)

-- 
2.9.5