Commit 6fa74755 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: factor out a bio_await helper 



Add a new helper to wait for a bio and anything chained off it to
complete synchronously after submitting it.  This factors common code out
of submit_bio_wait and bio_await_chain and will also be useful for
file system code and thus is exported.

Note that this will now set REQ_SYNC also for the bio_await case for
consistency.  Nothing should look at the flag in the end_io handler,
but if something does having the flag set makes more sense.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Link: https://patch.msgid.link/20260407140538.633364-4-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 65565ca5

block/bio.c

+37 −16
Original line number Diff line number Diff line
@@ -1468,17 +1468,20 @@ static void bio_wait_end_io(struct bio *bio) 
}



/**

 * submit_bio_wait - submit a bio, and wait until it completes

 * @bio: The &struct bio which describes the I/O

 * bio_await - call a function on a bio, and wait until it completes

 * @bio:	the bio which describes the I/O

 * @submit:	function called to submit the bio

 * @priv:	private data passed to @submit

 *

 * Simple wrapper around submit_bio(). Returns 0 on success, or the error from

 * bio_endio() on failure.

 * Wait for the bio as well as any bio chained off it after executing the

 * passed in callback @submit.  The wait for the bio is set up before calling

 * @submit to ensure that the completion is captured.  If @submit is %NULL,

 * submit_bio() is used instead to submit the bio.

 *

 * WARNING: Unlike to how submit_bio() is usually used, this function does not

 * result in bio reference to be consumed. The caller must drop the reference

 * on his own.

 * Note: this overrides the bi_private and bi_end_io fields in the bio.

 */

int submit_bio_wait(struct bio *bio)

void bio_await(struct bio *bio, void *priv,

	       void (*submit)(struct bio *bio, void *priv))

{

	DECLARE_COMPLETION_ONSTACK_MAP(done,

			bio->bi_bdev->bd_disk->lockdep_map);
@@ -1486,13 +1489,37 @@ int submit_bio_wait(struct bio *bio) 
	bio->bi_private = &done;

	bio->bi_end_io = bio_wait_end_io;

	bio->bi_opf |= REQ_SYNC;

	if (submit)

		submit(bio, priv);

	else

		submit_bio(bio);

	blk_wait_io(&done);

}

EXPORT_SYMBOL_GPL(bio_await);



/**

 * submit_bio_wait - submit a bio, and wait until it completes

 * @bio: The &struct bio which describes the I/O

 *

 * Simple wrapper around submit_bio(). Returns 0 on success, or the error from

 * bio_endio() on failure.

 *

 * WARNING: Unlike to how submit_bio() is usually used, this function does not

 * result in bio reference to be consumed. The caller must drop the reference

 * on his own.

 */

int submit_bio_wait(struct bio *bio)

{

	bio_await(bio, NULL, NULL);

	return blk_status_to_errno(bio->bi_status);

}

EXPORT_SYMBOL(submit_bio_wait);



static void bio_endio_cb(struct bio *bio, void *priv)

{

	bio_endio(bio);

}



/**

 * bdev_rw_virt - synchronously read into / write from kernel mapping

 * @bdev:	block device to access
@@ -1528,13 +1555,7 @@ EXPORT_SYMBOL_GPL(bdev_rw_virt); 
 */

void bio_await_chain(struct bio *bio)

{

	DECLARE_COMPLETION_ONSTACK_MAP(done,

			bio->bi_bdev->bd_disk->lockdep_map);



	bio->bi_private = &done;

	bio->bi_end_io = bio_wait_end_io;

	bio_endio(bio);

	blk_wait_io(&done);

	bio_await(bio, NULL, bio_endio_cb);

	bio_put(bio);

}

include/linux/bio.h

+2 −0
Original line number Diff line number Diff line
@@ -432,6 +432,8 @@ extern void bio_uninit(struct bio *); 
void bio_reset(struct bio *bio, struct block_device *bdev, blk_opf_t opf);

void bio_reuse(struct bio *bio, blk_opf_t opf);

void bio_chain(struct bio *, struct bio *);

void bio_await(struct bio *bio, void *priv,

	       void (*submit)(struct bio *bio, void *priv));



int __must_check bio_add_page(struct bio *bio, struct page *page, unsigned len,

			      unsigned off);