| Message ID | 546c66d26ae71abc151aa2074c3dd75ff5efb529.1605892141.git.asml.silence@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: don't ignore REQ_NOWAIT for direct IO | expand |
On 20/11/2020 17:10, Pavel Begunkov wrote: > io_uring's direct nowait requests end up waiting on io_schedule() in > sbitmap, that's seems to be so because blkdev_direct_IO() fails to > propagate IOCB_NOWAIT to a bio and hence to blk-mq. I'll leave it for judgement to those who know that code better, but io_schedule() is gone from my traces. > > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > --- > fs/block_dev.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index 9e84b1928b94..e7e860c78d93 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -263,6 +263,8 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, > bio.bi_opf = dio_bio_write_op(iocb); > task_io_account_write(ret); > } > + if (iocb->ki_flags & IOCB_NOWAIT) > + bio.bi_opf |= REQ_NOWAIT; > if (iocb->ki_flags & IOCB_HIPRI) > bio_set_polled(&bio, iocb); > > @@ -416,6 +418,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) > bio->bi_opf = dio_bio_write_op(iocb); > task_io_account_write(bio->bi_iter.bi_size); > } > + if (iocb->ki_flags & IOCB_NOWAIT) > + bio->bi_opf |= REQ_NOWAIT; > > dio->size += bio->bi_iter.bi_size; > pos += bio->bi_iter.bi_size; >
On 11/20/20 10:10 AM, Pavel Begunkov wrote: > io_uring's direct nowait requests end up waiting on io_schedule() in > sbitmap, that's seems to be so because blkdev_direct_IO() fails to > propagate IOCB_NOWAIT to a bio and hence to blk-mq. > > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > --- > fs/block_dev.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index 9e84b1928b94..e7e860c78d93 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -263,6 +263,8 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, > bio.bi_opf = dio_bio_write_op(iocb); > task_io_account_write(ret); > } > + if (iocb->ki_flags & IOCB_NOWAIT) > + bio.bi_opf |= REQ_NOWAIT; > if (iocb->ki_flags & IOCB_HIPRI) > bio_set_polled(&bio, iocb); Was thinking this wasn't needed, but I guess that users could do sync && NOWAIT and get -EAGAIN if using preadv2/pwritev2. > @@ -416,6 +418,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) > bio->bi_opf = dio_bio_write_op(iocb); > task_io_account_write(bio->bi_iter.bi_size); > } > + if (iocb->ki_flags & IOCB_NOWAIT) > + bio->bi_opf |= REQ_NOWAIT; > > dio->size += bio->bi_iter.bi_size; > pos += bio->bi_iter.bi_size; Looks fine to me, we definitely should not be waiting on tags for IOCB_NOWAIT IO. Will run some shakedown and test for 5.11.
On 20/11/2020 19:13, Jens Axboe wrote: > On 11/20/20 10:10 AM, Pavel Begunkov wrote: >> io_uring's direct nowait requests end up waiting on io_schedule() in >> sbitmap, that's seems to be so because blkdev_direct_IO() fails to >> propagate IOCB_NOWAIT to a bio and hence to blk-mq. >> >> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> >> --- >> fs/block_dev.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/fs/block_dev.c b/fs/block_dev.c >> index 9e84b1928b94..e7e860c78d93 100644 >> --- a/fs/block_dev.c >> +++ b/fs/block_dev.c >> @@ -263,6 +263,8 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, >> bio.bi_opf = dio_bio_write_op(iocb); >> task_io_account_write(ret); >> } >> + if (iocb->ki_flags & IOCB_NOWAIT) >> + bio.bi_opf |= REQ_NOWAIT; >> if (iocb->ki_flags & IOCB_HIPRI) >> bio_set_polled(&bio, iocb); > > Was thinking this wasn't needed, but I guess that users could do sync && NOWAIT > and get -EAGAIN if using preadv2/pwritev2. > >> @@ -416,6 +418,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) >> bio->bi_opf = dio_bio_write_op(iocb); >> task_io_account_write(bio->bi_iter.bi_size); >> } >> + if (iocb->ki_flags & IOCB_NOWAIT) >> + bio->bi_opf |= REQ_NOWAIT; >> >> dio->size += bio->bi_iter.bi_size; >> pos += bio->bi_iter.bi_size; > > Looks fine to me, we definitely should not be waiting on tags for IOCB_NOWAIT > IO. Will run some shakedown and test for 5.11. > up
On 11/20/20 10:10 AM, Pavel Begunkov wrote: > io_uring's direct nowait requests end up waiting on io_schedule() in > sbitmap, that's seems to be so because blkdev_direct_IO() fails to > propagate IOCB_NOWAIT to a bio and hence to blk-mq. Thanks, applied. This slipped through the cracks, and I didn't notice until I went and directly tested some of this... iomap suffers from the same issue, fwiw.
diff --git a/fs/block_dev.c b/fs/block_dev.c index 9e84b1928b94..e7e860c78d93 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -263,6 +263,8 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, bio.bi_opf = dio_bio_write_op(iocb); task_io_account_write(ret); } + if (iocb->ki_flags & IOCB_NOWAIT) + bio.bi_opf |= REQ_NOWAIT; if (iocb->ki_flags & IOCB_HIPRI) bio_set_polled(&bio, iocb); @@ -416,6 +418,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) bio->bi_opf = dio_bio_write_op(iocb); task_io_account_write(bio->bi_iter.bi_size); } + if (iocb->ki_flags & IOCB_NOWAIT) + bio->bi_opf |= REQ_NOWAIT; dio->size += bio->bi_iter.bi_size; pos += bio->bi_iter.bi_size;
io_uring's direct nowait requests end up waiting on io_schedule() in sbitmap, that's seems to be so because blkdev_direct_IO() fails to propagate IOCB_NOWAIT to a bio and hence to blk-mq. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- fs/block_dev.c | 4 ++++ 1 file changed, 4 insertions(+)