Re: [PATCH 03/26] block: wire up block device iopoll method
On 12/6/18 12:15 PM, Christoph Hellwig wrote: > On Thu, Dec 06, 2018 at 12:14:29PM -0700, Jens Axboe wrote: >> On 12/6/18 12:11 PM, Jeff Moyer wrote: >>> Jens Axboe writes: >>> From: Christoph Hellwig Just call blk_poll on the iocb cookie, we can derive the block device from the inode trivially. >>> >>> Does this work for multi-device file systems? >> >> It should, that's the whole purpose of having fops->iopoll. You should >> be able to derive it from inode + cookie. > > It still assumes the whole I/O will got to a single device. For > XFS this is always tree, but for btrfs this might mean I/O could > need splitting if ->iopoll was to be supported there. Right, we can only support one target for one particular piece of IO, but multi-device works fine in general. -- Jens Axboe
Re: [PATCH 03/26] block: wire up block device iopoll method
On Thu, Dec 06, 2018 at 12:14:29PM -0700, Jens Axboe wrote: > On 12/6/18 12:11 PM, Jeff Moyer wrote: > > Jens Axboe writes: > > > >> From: Christoph Hellwig > >> > >> Just call blk_poll on the iocb cookie, we can derive the block device > >> from the inode trivially. > > > > Does this work for multi-device file systems? > > It should, that's the whole purpose of having fops->iopoll. You should > be able to derive it from inode + cookie. It still assumes the whole I/O will got to a single device. For XFS this is always tree, but for btrfs this might mean I/O could need splitting if ->iopoll was to be supported there.
Re: [PATCH 03/26] block: wire up block device iopoll method
On 12/6/18 12:11 PM, Jeff Moyer wrote: > Jens Axboe writes: > >> From: Christoph Hellwig >> >> Just call blk_poll on the iocb cookie, we can derive the block device >> from the inode trivially. > > Does this work for multi-device file systems? It should, that's the whole purpose of having fops->iopoll. You should be able to derive it from inode + cookie. -- Jens Axboe
Re: [PATCH 03/26] block: wire up block device iopoll method
Jens Axboe writes:
> From: Christoph Hellwig
>
> Just call blk_poll on the iocb cookie, we can derive the block device
> from the inode trivially.
Does this work for multi-device file systems?
-Jeff
>
> Reviewed-by: Johannes Thumshirn
> Signed-off-by: Christoph Hellwig
> Signed-off-by: Jens Axboe
> ---
> fs/block_dev.c | 10 ++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index e1886cc7048f..6de8d35f6e41 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -281,6 +281,14 @@ struct blkdev_dio {
>
> static struct bio_set blkdev_dio_pool;
>
> +static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
> +{
> + struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
> + struct request_queue *q = bdev_get_queue(bdev);
> +
> + return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
> +}
> +
> static void blkdev_bio_end_io(struct bio *bio)
> {
> struct blkdev_dio *dio = bio->bi_private;
> @@ -398,6 +406,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter
> *iter, int nr_pages)
> bio->bi_opf |= REQ_HIPRI;
>
> qc = submit_bio(bio);
> + WRITE_ONCE(iocb->ki_cookie, qc);
> break;
> }
>
> @@ -2070,6 +2079,7 @@ const struct file_operations def_blk_fops = {
> .llseek = block_llseek,
> .read_iter = blkdev_read_iter,
> .write_iter = blkdev_write_iter,
> + .iopoll = blkdev_iopoll,
> .mmap = generic_file_mmap,
> .fsync = blkdev_fsync,
> .unlocked_ioctl = block_ioctl,
