block: add ->poll_bio to block_device_operations

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>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/block/blk-core.c b/block/blk-core.c
index 94bf37f..ce08f0a 100644 (file)
--- 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 e351fac..1ed46a6 100644 (file)
--- 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 f757f9c..51f1b1d 100644 (file)
--- 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);