Hi Christoph,
在 2021/10/12 19:12, Christoph Hellwig 写道:
Replace the blk_poll interface that requires the caller to keep a queue
and cookie from the submissions with polling based on the bio.
Polling for the bio itself leads to a few advantages:
- the cookie construction can made entirely private in blk-mq.c
- the caller does not need to remember the request_queue and cookie
separately and thus sidesteps their lifetime issues
- keeping the device and the cookie inside the bio allows to trivially
support polling BIOs remapping by stacking drivers
- a lot of code to propagate the cookie back up the submission path can
be removed entirely.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Tested-by: Mark Wunderlich <mark.wunderlich@xxxxxxxxx>
---
......
/**
* blk_cloned_rq_check_limits - Helper function to check a cloned request
* for the new queue limits
diff --git a/block/blk-exec.c b/block/blk-exec.c
index 1fa7f25e57262..55f0cd34b37b9 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -65,13 +65,19 @@ EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
static bool blk_rq_is_poll(struct request *rq)
{
- return rq->mq_hctx && rq->mq_hctx->type == HCTX_TYPE_POLL;
+ if (!rq->mq_hctx)
+ return false;
+ if (rq->mq_hctx->type != HCTX_TYPE_POLL)
+ return false;
+ if (WARN_ON_ONCE(!rq->bio))
+ return false;
+ return true;
}
static void blk_rq_poll_completion(struct request *rq, struct completion *wait)
{
do {
- blk_poll(rq->q, request_to_qc_t(rq->mq_hctx, rq), 0);
+ bio_poll(rq->bio, 0);
cond_resched();
} while (!completion_done(wait));
}
For some scsi command sent by function __scsi_execute() without data, it
has request but no bio (bufflen = 0),
then how to use bio_poll() for them ?
Best Regards,
Xiang Chen
