Re: [PATCH 07/17] uml: convert ubd to blk-mq

Ming Lei
2018-10-15T10:27:18Z

On Thu, Oct 11, 2018 at 10:58:59AM -0600, Jens Axboe wrote:
> Just a straight forward conversion. The retry handling could
> potentially be done by blk-mq as well, but that's for another
> day.
>
> Cc: Jeff Dike <jdike@addtoit.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
> arch/um/drivers/ubd_kern.c | 154 ++++++++++++++++++++++---------------
> 1 file changed, 94 insertions(+), 60 deletions(-)
>
> diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
> index 83c470364dfb..a302962a441d 100644
> --- a/arch/um/drivers/ubd_kern.c
> +++ b/arch/um/drivers/ubd_kern.c
> @@ -22,7 +22,7 @@
>
> #include <linux/module.h>
> #include <linux/init.h>
> -#include <linux/blkdev.h>
> +#include <linux/blk-mq.h>
> #include <linux/ata.h>
> #include <linux/hdreg.h>
> #include <linux/cdrom.h>
> @@ -156,6 +156,7 @@ struct ubd {
> struct cow cow;
> struct platform_device pdev;
> struct request_queue *queue;
> + struct blk_mq_tag_set tag_set;
> spinlock_t lock;
> struct scatterlist sg[MAX_SG];
> struct request *request;
> @@ -436,7 +437,9 @@ __uml_help(udb_setup,
> " in the boot output.\n\n"
> );
>
> -static void do_ubd_request(struct request_queue * q);
> +static void ubd_handle_request(struct ubd *dev);
> +static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
> + const struct blk_mq_queue_data *bd);
>
> /* Only changed by ubd_init, which is an initcall. */
> static int thread_fd = -1;
> @@ -520,12 +523,12 @@ static void ubd_handler(void)
> return;
> }
> for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
> - blk_end_request(
> - (*irq_req_buffer)[count]->req,
> - BLK_STS_OK,
> - (*irq_req_buffer)[count]->length
> - );
> - kfree((*irq_req_buffer)[count]);
> + struct io_thread_req *io_req = (*irq_req_buffer)[count];
> +
> + if (!blk_update_request(io_req->req, BLK_STS_OK, io_req->length))
> + __blk_mq_end_request(io_req->req, BLK_STS_OK);
> +
> + kfree(io_req);
> }
> }
> reactivate_fd(thread_fd, UBD_IRQ);
> @@ -534,7 +537,7 @@ static void ubd_handler(void)
> ubd = container_of(list, struct ubd, restart);
> list_del_init(&ubd->restart);
> spin_lock_irqsave(&ubd->lock, flags);
> - do_ubd_request(ubd->queue);
> + ubd_handle_request(ubd);
> spin_unlock_irqrestore(&ubd->lock, flags);
> }
> }
> @@ -856,6 +859,7 @@ static void ubd_device_release(struct device *dev)
> {
> struct ubd *ubd_dev = dev_get_drvdata(dev);
>
> + blk_mq_free_tag_set(&ubd_dev->tag_set);
> blk_cleanup_queue(ubd_dev->queue);
> *ubd_dev = ((struct ubd) DEFAULT_UBD);
> }
> @@ -897,20 +901,25 @@ static int ubd_disk_register(int major, u64 size, int unit,
> return 0;
> }
>
> +static const struct blk_mq_ops ubd_mq_ops = {
> + .queue_rq = ubd_queue_rq,
> +};
> +
> #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
>
> static int ubd_add(int n, char **error_out)
> {
> struct ubd *ubd_dev = &ubd_devs[n];
> + struct blk_mq_tag_set *set;
> int err = 0;
>
> if(ubd_dev->file == NULL)
> - goto out;
> + goto out1;
>
> err = ubd_file_size(ubd_dev, &ubd_dev->size);
> if(err < 0){
> *error_out = "Couldn't determine size of device's file";
> - goto out;
> + goto out1;
> }
>
> ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
> @@ -918,12 +927,26 @@ static int ubd_add(int n, char **error_out)
> INIT_LIST_HEAD(&ubd_dev->restart);
> sg_init_table(ubd_dev->sg, MAX_SG);
>
> - err = -ENOMEM;
> - ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
> - if (ubd_dev->queue == NULL) {
> + set = &ubd_dev->tag_set;
> + set->ops = &ubd_mq_ops;
> + set->nr_hw_queues = 1;
> + set->queue_depth = 2;
> + set->numa_node = NUMA_NO_NODE;
> + set->flags = BLK_MQ_F_SHOULD_MERGE;
> + err = blk_mq_alloc_tag_set(set);
> + if (err) {
> + *error_out = "Failed to initialize device tag set";
> + goto out1;
> + }
> +
> + ubd_dev->queue = blk_mq_init_queue(set);
> + if (IS_ERR(ubd_dev->queue)) {
> + err = PTR_ERR(ubd_dev->queue);
> + ubd_dev->queue = NULL;
> *error_out = "Failed to initialize device queue";
> goto out;
> }
> +
> ubd_dev->queue->queuedata = ubd_dev;
> blk_queue_write_cache(ubd_dev->queue, true, false);
>
> @@ -947,9 +970,12 @@ static int ubd_add(int n, char **error_out)
>
> err = 0;
> out:
> + blk_mq_free_tag_set(&ubd_dev->tag_set);
> +out1:
> return err;
>
> out_cleanup:
> + blk_mq_free_tag_set(&ubd_dev->tag_set);
> blk_cleanup_queue(ubd_dev->queue);

blk_mq_free_tag_set() should have been put after blk_cleanup_queue().

--
Ming