Re: [PATCH 1/8] iomap: cleanup up iomap_dio_bio_end_io()

Darrick J. Wong
2023-07-21T15:13:53Z

On Thu, Jul 20, 2023 at 12:13:03PM -0600, Jens Axboe wrote:
> Make the logic a bit easier to follow:
>
> 1) Add a release_bio out path, as everybody needs to touch that, and
> have our bio ref check jump there if it's non-zero.
> 2) Add a kiocb local variable.
> 3) Add comments for each of the three conditions (sync, inline, or
> async workqueue punt).
>
> No functional changes in this patch.
>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

Thanks for deindentifying this,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
> fs/iomap/direct-io.c | 46 +++++++++++++++++++++++++++++---------------
> 1 file changed, 31 insertions(+), 15 deletions(-)
>
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index ea3b868c8355..0ce60e80c901 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -152,27 +152,43 @@ void iomap_dio_bio_end_io(struct bio *bio)
> {
> struct iomap_dio *dio = bio->bi_private;
> bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
> + struct kiocb *iocb = dio->iocb;
>
> if (bio->bi_status)
> iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
> + if (!atomic_dec_and_test(&dio->ref))
> + goto release_bio;
>
> - if (atomic_dec_and_test(&dio->ref)) {
> - if (dio->wait_for_completion) {
> - struct task_struct *waiter = dio->submit.waiter;
> - WRITE_ONCE(dio->submit.waiter, NULL);
> - blk_wake_io_task(waiter);
> - } else if (dio->flags & IOMAP_DIO_WRITE) {
> - struct inode *inode = file_inode(dio->iocb->ki_filp);
> -
> - WRITE_ONCE(dio->iocb->private, NULL);
> - INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
> - queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
> - } else {
> - WRITE_ONCE(dio->iocb->private, NULL);
> - iomap_dio_complete_work(&dio->aio.work);
> - }
> + /*
> + * Synchronous dio, task itself will handle any completion work
> + * that needs after IO. All we need to do is wake the task.
> + */
> + if (dio->wait_for_completion) {
> + struct task_struct *waiter = dio->submit.waiter;
> +
> + WRITE_ONCE(dio->submit.waiter, NULL);
> + blk_wake_io_task(waiter);
> + goto release_bio;
> + }
> +
> + /* Read completion can always complete inline. */
> + if (!(dio->flags & IOMAP_DIO_WRITE)) {
> + WRITE_ONCE(iocb->private, NULL);
> + iomap_dio_complete_work(&dio->aio.work);
> + goto release_bio;
> }
>
> + /*
> + * Async DIO completion that requires filesystem level completion work
> + * gets punted to a work queue to complete as the operation may require
> + * more IO to be issued to finalise filesystem metadata changes or
> + * guarantee data integrity.
> + */
> + WRITE_ONCE(iocb->private, NULL);
> + INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
> + queue_work(file_inode(iocb->ki_filp)->i_sb->s_dio_done_wq,
> + &dio->aio.work);
> +release_bio:
> if (should_dirty) {
> bio_check_pages_dirty(bio);
> } else {
> --
> 2.40.1
>