[PATCH v4 0/2] blk-mq: fix start_time_ns and alloc_time_ns for pre-allocated rq

[chengming.zhou@linux.dev]

From: Chengming Zhou <zhouchengming@bytedance.com>

Hello,

This patchset fix start_time_ns and alloc_time_ns for pre-allocated rq.

patch 1 is preparation that we move data->rq_flags initialization code
outside blk_mq_rq_ctx_init() to its caller, since we will need it to
tell if we need to get start_time_ns.

patch 2 is the fix patch that we set alloc_time_ns and start_time_ns
to now when the pre-allocated rq is actually used and we skip setting
during pre-allocation.

v4:
 - Combine the last two patches into one patch for clearer review.
 - Use blk_mq_alloc_data to pass start_time_ns instead of passing down
   yet another parameter. Thanks Christoph Hellwig.
 - [v3] https://lore.kernel.org/all/20230628124546.1056698-1-chengming.zhou@linux.dev/

v3:
 - Skip setting the alloc_time_ns and start_time_ns during pre-allocation,
   which is clearer, as suggested by Tejun.
 - [v2] https://lore.kernel.org/all/20230626050405.781253-1-chengming.zhou@linux.dev/

v2:
 - Let blk_mq_rq_ctx_init() receive start_time_ns for batched time setting.
 - Set alloc_time_ns and start_time_ns when the pre-allocated rq is actually
   used, as suggested by Tejun.
 - [v1] https://lore.kernel.org/all/20230601053919.3639954-1-chengming.zhou@linux.dev/

Chengming Zhou (2):
  blk-mq: move data->rq_flags initialization code
  blk-mq: fix start_time_ns and alloc_time_ns for pre-allocated rq

 block/blk-mq.c         | 87 ++++++++++++++++++++++++------------------
 block/blk-mq.h         |  1 +
 include/linux/blk-mq.h |  6 +--
 3 files changed, 53 insertions(+), 41 deletions(-)

-- 
2.39.2