[PATCH v6 1/2] block: add ->poll_bio to block_device_operations

Mike Snitzer
2022-03-07T18:57:12Z

From: Ming Lei <ming.lei@redhat.com>

Prepare for supporting IO polling for bio-based driver.

Add ->poll_bio callback so that bio-based driver can provide their own
logic for polling bio.

Also fix ->submit_bio_bio typo in comment block above
__submit_bio_noacct.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
block/blk-core.c | 14 +++++++++-----
block/genhd.c | 4 ++++
include/linux/blkdev.h | 2 ++
3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 94bf37f8e61d..ce08f0aa9dfc 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -708,7 +708,7 @@ static void __submit_bio(struct bio *bio)
*
* bio_list_on_stack[0] contains bios submitted by the current ->submit_bio.
* bio_list_on_stack[1] contains bios that were submitted before the current
- * ->submit_bio_bio, but that haven't been processed yet.
+ * ->submit_bio, but that haven't been processed yet.
*/
static void __submit_bio_noacct(struct bio *bio)
{
@@ -975,7 +975,7 @@ int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
blk_qc_t cookie = READ_ONCE(bio->bi_cookie);
- int ret;
+ int ret = 0;

if (cookie == BLK_QC_T_NONE ||
!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
@@ -985,10 +985,14 @@ int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags)

if (blk_queue_enter(q, BLK_MQ_REQ_NOWAIT))
return 0;
- if (WARN_ON_ONCE(!queue_is_mq(q)))
- ret = 0; /* not yet implemented, should not happen */
- else
+ if (queue_is_mq(q)) {
ret = blk_mq_poll(q, cookie, iob, flags);
+ } else {
+ struct gendisk *disk = q->disk;
+
+ if (disk && disk->fops->poll_bio)
+ ret = disk->fops->poll_bio(bio, iob, flags);
+ }
blk_queue_exit(q);
return ret;
}
diff --git a/block/genhd.c b/block/genhd.c
index e351fac41bf2..1ed46a6f94f5 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -410,6 +410,10 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
struct device *ddev = disk_to_dev(disk);
int ret;

+ /* Only makes sense for bio-based to set ->poll_bio */
+ if (queue_is_mq(disk->queue) && disk->fops->poll_bio)
+ return -EINVAL;
+
/*
* The disk queue should now be all set with enough information about
* the device for the elevator code to pick an adequate default
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f757f9c2871f..51f1b1ddbed2 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1455,6 +1455,8 @@ enum blk_unique_id {

struct block_device_operations {
void (*submit_bio)(struct bio *bio);
+ int (*poll_bio)(struct bio *bio, struct io_comp_batch *iob,
+ unsigned int flags);
int (*open) (struct block_device *, fmode_t);
void (*release) (struct gendisk *, fmode_t);
int (*rw_page)(struct block_device *, sector_t, struct page *, unsigned int);
--
2.15.0