[PATCH 02/16] block: don't try to poll multi-bio I/Os in __blkdev_direct_IO
From: Christoph Hellwig <hch@lst.de>
Date: 2021-06-15 13:11:37
Also in:
linux-fsdevel, linux-nvme
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
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 | 21 +++++++-------------- 1 file changed, 7 insertions(+), 14 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index ac9b3c158a77..8600c651b0b0 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 do_poll = (iocb->ki_flags & IOCB_HIPRI); bool is_read = (iov_iter_rw(iter) == READ), is_sync; loff_t pos = iocb->ki_pos; blk_qc_t qc = BLK_QC_T_NONE;
@@ -404,7 +404,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, * Don't plug for HIPRI/polled IO, as those should go straight * to issue */ - if (!is_poll) + if (!(iocb->ki_flags & IOCB_HIPRI)) blk_start_plug(&plug); for (;;) {
@@ -438,20 +438,13 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS); if (!nr_pages) { - bool polled = false; - - if (iocb->ki_flags & IOCB_HIPRI) { + if (do_poll) bio_set_polled(bio, iocb); - polled = true; - } - qc = submit_bio(bio); - - if (polled) + if (do_poll) WRITE_ONCE(iocb->ki_cookie, qc); break; } - if (!dio->multi_bio) { /* * AIO needs an extra reference to ensure the dio
@@ -462,6 +455,7 @@ 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); + do_poll = false; } else { atomic_inc(&dio->ref); }
@@ -470,7 +464,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, bio = bio_alloc(GFP_KERNEL, nr_pages); } - if (!is_poll) + if (!(iocb->ki_flags & IOCB_HIPRI)) blk_finish_plug(&plug); if (!is_sync)
@@ -481,8 +475,7 @@ 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);
--
2.30.2