[dm-devel] [PATCH V4 04/12] block: add req flag of REQ_POLL_CTX

[Hannes Reinecke]

On 3/29/21 5:26 PM, Ming Lei wrote:
> Add one req flag REQ_POLL_CTX which will be used in the following patch for
> supporting bio based IO polling.
> 
> Exactly this flag can help us to do:
> 
> 1) request flag is cloned in bio_fast_clone(), so if we mark one FS bio
> as REQ_POLL_CTX, all bios cloned from this FS bio will be marked as
> REQ_POLL_CTX too.
> 
> 2) create per-task io polling context if the bio based queue supports
> polling and the submitted bio is HIPRI. Per-task io poll context will be
> created during submit_bio() before marking this HIPRI bio as REQ_POLL_CTX.
> Then we can avoid to create such io polling context if one cloned bio with
> REQ_POLL_CTX is submitted from another kernel context.
> 
> 3) for supporting bio based io polling, we need to poll IOs from all
> underlying queues of the bio device, this way help us to recognize which
> IO needs to polled in bio based style, which will be applied in
> following patch.
> 
> Reviewed-by: Jeffle Xu <jefflexu at linux.alibaba.com>
> Signed-off-by: Ming Lei <ming.lei at redhat.com>
> ---
>   block/blk-core.c          | 28 ++++++++++++++++++++++++++--
>   include/linux/blk_types.h |  4 ++++
>   2 files changed, 30 insertions(+), 2 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare at suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
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