在 2020/11/18 下午7:51, Hao Xu 写道:
Currently, IOCB_NOWAIT is ignored in Direct IO, REQ_NOWAIT is only set
when IOCB_HIPRI is set. But REQ_NOWAIT should be set as well when
IOCB_NOWAIT is set.
Signed-off-by: Hao Xu <haoxu@xxxxxxxxxxxxxxxxx>
---
Hi all,
I tested fio io_uring direct read for a file on ext4 filesystem on a
nvme ssd. I found that IOCB_NOWAIT is ignored in iomap layer, which
means REQ_NOWAIT is not set in bio->bi_opf. This makes nowait IO a
normal IO. Since I'm new to iomap and block layer, I sincerely ask
yours opinions in case I misunderstand the code which is very likely
to happen.:)
v1->v2:
* add same logic in __blkdev_direct_IO_simple()
fs/block_dev.c | 7 +++++++
fs/iomap/direct-io.c | 3 +++
2 files changed, 10 insertions(+)
ping...
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 9e84b1928b94..f3e9e13a9a9f 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -263,6 +263,10 @@ static void blkdev_bio_end_io_simple(struct bio *bio)
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);
@@ -424,6 +428,9 @@ static void blkdev_bio_end_io(struct bio *bio)
if (!nr_pages) {
bool polled = false;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ bio->bi_opf |= REQ_NOWAIT;
+
if (iocb->ki_flags & IOCB_HIPRI) {
bio_set_polled(bio, iocb);
polled = true;
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 933f234d5bec..2e897688ed6d 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -64,6 +64,9 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
{
atomic_inc(&dio->ref);
+ if (dio->iocb->ki_flags & IOCB_NOWAIT)
+ bio->bi_opf |= REQ_NOWAIT;
+
if (dio->iocb->ki_flags & IOCB_HIPRI)
bio_set_polled(bio, dio->iocb);
