| Message ID | 20200425170944.968861-7-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/11] block: improve the kerneldoc comments for submit_bio and generic_make_request | expand |
On Sat, Apr 25, 2020 at 07:09:39PM +0200, Christoph Hellwig wrote: > Don't bother with the on-stack bio list if we know that we directly > issue to a request based driver that can't re-inject bios. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > block/blk-core.c | 29 +++++++++++++++++++---------- > 1 file changed, 19 insertions(+), 10 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index 732d5b8d3cd25..e8c48203b2c55 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -1008,6 +1008,18 @@ generic_make_request_checks(struct bio *bio) > return false; > } > > +static inline blk_qc_t __direct_make_request(struct bio *bio) > +{ > + struct request_queue *q = bio->bi_disk->queue; > + blk_qc_t ret; > + > + if (unlikely(bio_queue_enter(bio))) > + return BLK_QC_T_NONE; > + ret = blk_mq_make_request(q, bio); > + blk_queue_exit(q); > + return ret; > +} > + > static blk_qc_t do_make_request(struct bio *bio, > struct bio_list bio_list_on_stack[2]) > { > @@ -1116,7 +1128,10 @@ blk_qc_t generic_make_request(struct bio *bio) > return BLK_QC_T_NONE; > } > > - return __generic_make_request(bio); > + if (bio->bi_disk->queue->make_request_fn) > + return __generic_make_request(bio); > + return __direct_make_request(bio); > + blk_mq_make_request() still calls into generic_make_request(), so bio may be added to current->bio_list, then looks __direct_make_request() can't cover recursive bio submission any more. Thanks, Ming
On Sun, Apr 26, 2020 at 10:53:52AM +0800, Ming Lei wrote: > blk_mq_make_request() still calls into generic_make_request(), so bio > may be added to current->bio_list, then looks __direct_make_request() > can't cover recursive bio submission any more. True, we can't do the series as-is.
diff --git a/block/blk-core.c b/block/blk-core.c index 732d5b8d3cd25..e8c48203b2c55 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1008,6 +1008,18 @@ generic_make_request_checks(struct bio *bio) return false; } +static inline blk_qc_t __direct_make_request(struct bio *bio) +{ + struct request_queue *q = bio->bi_disk->queue; + blk_qc_t ret; + + if (unlikely(bio_queue_enter(bio))) + return BLK_QC_T_NONE; + ret = blk_mq_make_request(q, bio); + blk_queue_exit(q); + return ret; +} + static blk_qc_t do_make_request(struct bio *bio, struct bio_list bio_list_on_stack[2]) { @@ -1116,7 +1128,10 @@ blk_qc_t generic_make_request(struct bio *bio) return BLK_QC_T_NONE; } - return __generic_make_request(bio); + if (bio->bi_disk->queue->make_request_fn) + return __generic_make_request(bio); + return __direct_make_request(bio); + } EXPORT_SYMBOL(generic_make_request); @@ -1130,20 +1145,14 @@ EXPORT_SYMBOL(generic_make_request); */ blk_qc_t direct_make_request(struct bio *bio) { - struct request_queue *q = bio->bi_disk->queue; - blk_qc_t ret; - - if (WARN_ON_ONCE(q->make_request_fn)) { + if (WARN_ON_ONCE(bio->bi_disk->queue->make_request_fn)) { bio_io_error(bio); return BLK_QC_T_NONE; } + if (!generic_make_request_checks(bio)) return BLK_QC_T_NONE; - if (unlikely(bio_queue_enter(bio))) - return BLK_QC_T_NONE; - ret = blk_mq_make_request(q, bio); - blk_queue_exit(q); - return ret; + return __direct_make_request(bio); } EXPORT_SYMBOL_GPL(direct_make_request);
Don't bother with the on-stack bio list if we know that we directly issue to a request based driver that can't re-inject bios. Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/blk-core.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-)