| Message ID | 20210512131545.495160-3-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/15] direct-io: remove blk_poll support | expand |
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
On Wed, May 12, 2021 at 6:50 PM Christoph Hellwig <hch@lst.de> wrote: > > If an iocb is split into multiple bios we can't poll for both. So don't > bother to even try to poll in that case. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/block_dev.c | 37 ++++++++++++++----------------------- > 1 file changed, 14 insertions(+), 23 deletions(-) > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index b8abccd03e5d..0080a3b710b4 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -375,7 +375,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, > struct blk_plug plug; > struct blkdev_dio *dio; > struct bio *bio; > - bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0; > + bool is_poll = (iocb->ki_flags & IOCB_HIPRI), do_poll = false; > bool is_read = (iov_iter_rw(iter) == READ), is_sync; > loff_t pos = iocb->ki_pos; > blk_qc_t qc = BLK_QC_T_NONE; > @@ -437,22 +437,9 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, > pos += bio->bi_iter.bi_size; > > nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS); > - if (!nr_pages) { > - bool polled = false; > - > - if (iocb->ki_flags & IOCB_HIPRI) { > - bio_set_polled(bio, iocb); > - polled = true; > - } > - > - qc = submit_bio(bio); > - > - if (polled) > - WRITE_ONCE(iocb->ki_cookie, qc); > - break; > - } > - > - if (!dio->multi_bio) { > + if (dio->multi_bio) { > + atomic_inc(&dio->ref); > + } else if (nr_pages) { > /* > * AIO needs an extra reference to ensure the dio > * structure which is embedded into the first bio > @@ -462,11 +449,16 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, > bio_get(bio); > dio->multi_bio = true; > atomic_set(&dio->ref, 2); > - } else { > - atomic_inc(&dio->ref); > + } else if (is_poll) { > + bio_set_polled(bio, iocb); > + do_poll = true; > + } > + qc = submit_bio(bio); > + if (!nr_pages) { > + if (do_poll) > + WRITE_ONCE(iocb->ki_cookie, qc); > + break; > } > - > - submit_bio(bio); > bio = bio_alloc(GFP_KERNEL, nr_pages); > } dio->ref update goes amiss here. For multi-bio, if the original code sets it as N, this will set it as N+1, causing endless-wait for the caller.
diff --git a/fs/block_dev.c b/fs/block_dev.c index b8abccd03e5d..0080a3b710b4 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -375,7 +375,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, struct blk_plug plug; struct blkdev_dio *dio; struct bio *bio; - bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0; + bool is_poll = (iocb->ki_flags & IOCB_HIPRI), do_poll = false; bool is_read = (iov_iter_rw(iter) == READ), is_sync; loff_t pos = iocb->ki_pos; blk_qc_t qc = BLK_QC_T_NONE; @@ -437,22 +437,9 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, pos += bio->bi_iter.bi_size; nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS); - if (!nr_pages) { - bool polled = false; - - if (iocb->ki_flags & IOCB_HIPRI) { - bio_set_polled(bio, iocb); - polled = true; - } - - qc = submit_bio(bio); - - if (polled) - WRITE_ONCE(iocb->ki_cookie, qc); - break; - } - - if (!dio->multi_bio) { + if (dio->multi_bio) { + atomic_inc(&dio->ref); + } else if (nr_pages) { /* * AIO needs an extra reference to ensure the dio * structure which is embedded into the first bio @@ -462,11 +449,16 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, bio_get(bio); dio->multi_bio = true; atomic_set(&dio->ref, 2); - } else { - atomic_inc(&dio->ref); + } else if (is_poll) { + bio_set_polled(bio, iocb); + do_poll = true; + } + qc = submit_bio(bio); + if (!nr_pages) { + if (do_poll) + WRITE_ONCE(iocb->ki_cookie, qc); + break; } - - submit_bio(bio); bio = bio_alloc(GFP_KERNEL, nr_pages); } @@ -481,8 +473,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, if (!READ_ONCE(dio->waiter)) break; - if (!(iocb->ki_flags & IOCB_HIPRI) || - !blk_poll(bdev_get_queue(bdev), qc, true)) + if (!do_poll || !blk_poll(bdev_get_queue(bdev), qc, true)) blk_io_schedule(); } __set_current_state(TASK_RUNNING);
If an iocb is split into multiple bios we can't poll for both. So don't bother to even try to poll in that case. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/block_dev.c | 37 ++++++++++++++----------------------- 1 file changed, 14 insertions(+), 23 deletions(-)