On Wed, Mar 24, 2021 at 04:32:31PM +0100, Hannes Reinecke wrote: > On 3/24/21 1:19 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. > > > > Signed-off-by: Ming Lei <[email protected]> > > --- > > block/blk-core.c | 25 ++++++++++++++++++++++++- > > include/linux/blk_types.h | 4 ++++ > > 2 files changed, 28 insertions(+), 1 deletion(-) > > > > diff --git a/block/blk-core.c b/block/blk-core.c > > index 4671bbf31fd3..eb07d61cfdc2 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 polling without per-task poll ctx > > + * > > + * We have created per-task io poll context, and mark this > > + * bio as REQ_POLL_CTX, so: 1) if any cloned bio from this bio is > > + * submitted from another kernel context, we won't create bio > > + * poll context for it, and that bio can 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_HIPRI & REQ_POLL_CTX 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_POLL_CTX; > > } > > static noinline_for_stack bool submit_bio_checks(struct bio *bio) > > @@ -894,8 +913,12 @@ static noinline_for_stack bool > > submit_bio_checks(struct bio *bio) > > /* > > * Create per-task io poll ctx if bio polling supported and HIPRI > > * set. > > + * > > + * If REQ_POLL_CTX isn't set for this HIPRI bio, we think it originated > > + * from FS and allocate io polling context. > > */ > > blk_create_io_context(q, blk_queue_support_bio_poll(q) && > > + !(bio->bi_opf & REQ_POLL_CTX) && > > (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..99160d588c2d 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_POLL_CTX, > > + > > /* 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_POLL_CTX (1ULL << __REQ_POLL_CTX) > > #define REQ_DRV (1ULL << __REQ_DRV) > > #define REQ_SWAP (1ULL << __REQ_SWAP) > > > What happens to split bios? > Will they be tracked similarly to cloned bios? > If so, shouldn't you document that here, too?
split bios are simply cloned bios, please see bio_split(). thanks, Ming -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
