Add one req flag REQ_TAG 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_TAG, all bios cloned from this FS bio will be marked as REQ_TAG. 2)create per-task io polling context if the bio based queue supports polling and the submitted bio is HIPRI. This per-task io polling context will be created during submit_bio() before marking this HIPRI bio as REQ_TAG. Then we can avoid to create such io polling context if one cloned bio with REQ_TAG is submitted from another kernel context. 3) for supporting bio based io polling, we need to poll IOs from all underlying queues of bio device/driver, this way help us to recognize which IOs need to polled in bio based style, which will be implemented in next patch. Signed-off-by: Ming Lei <[email protected]> --- block/blk-core.c | 29 +++++++++++++++++++++++++++-- include/linux/blk_types.h | 4 ++++ 2 files changed, 31 insertions(+), 2 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 0b00c21cbefb..efc7a61a84b4 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -840,11 +840,30 @@ static inline bool blk_queue_support_bio_poll(struct request_queue *q) static inline void blk_bio_poll_preprocess(struct request_queue *q, struct bio *bio) { + bool mq; + if (!(bio->bi_opf & REQ_HIPRI)) return; - if (!blk_queue_poll(q) || (!queue_is_mq(q) && !blk_get_bio_poll_ctx())) + /* + * Can't support bio based IO poll without per-task poll queue + * + * Now we have created per-task io poll context, and mark this + * bio as REQ_TAG, so: 1) if any cloned bio from this bio is + * submitted from another kernel context, we won't create bio + * poll context for it, so that bio will be completed by IRQ; + * 2) If such bio is submitted from current context, we will + * complete it via blk_poll(); 3) If driver knows that one + * underlying bio allocated from driver is for FS bio, meantime + * it is submitted in current context, driver can mark such bio + * as REQ_TAG manually, so the bio can be completed via blk_poll + * too. + */ + mq = queue_is_mq(q); + if (!blk_queue_poll(q) || (!mq && !blk_get_bio_poll_ctx())) bio->bi_opf &= ~REQ_HIPRI; + else if (!mq) + bio->bi_opf |= REQ_TAG; } static noinline_for_stack bool submit_bio_checks(struct bio *bio) @@ -893,9 +912,15 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio) /* * Created per-task io poll queue if we supports bio polling - * and it is one HIPRI bio. + * and it is one HIPRI bio, and this HIPRI bio has to be from + * FS. If REQ_TAG isn't set for HIPRI bio, we think it originated + * from FS. + * + * Driver may allocated bio by itself and REQ_TAG is set, but they + * won't be marked as HIPRI. */ blk_create_io_context(q, blk_queue_support_bio_poll(q) && + !(bio->bi_opf & REQ_TAG) && (bio->bi_opf & REQ_HIPRI)); blk_bio_poll_preprocess(q, bio); diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index db026b6ec15a..a1bcade4bcc3 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -394,6 +394,9 @@ enum req_flag_bits { __REQ_HIPRI, + /* for marking IOs originated from same FS bio in same context */ + __REQ_TAG, + /* for driver use */ __REQ_DRV, __REQ_SWAP, /* swapping request. */ @@ -418,6 +421,7 @@ enum req_flag_bits { #define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP) #define REQ_HIPRI (1ULL << __REQ_HIPRI) +#define REQ_TAG (1ULL << __REQ_TAG) #define REQ_DRV (1ULL << __REQ_DRV) #define REQ_SWAP (1ULL << __REQ_SWAP) -- 2.29.2 -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
