ms_block: convert to blk-mq

Straight forward conversion, room for optimization in how everything
is punted to a work queue. Also looks plenty racy all over the map,
with the state changes. I fixed a bunch of them up while doing the
conversion, but there are surely more.

Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/memstick/core/ms_block.c b/drivers/memstick/core/ms_block.c
index 8a02f11..ee0be66 100644 (file)
--- a/drivers/memstick/core/ms_block.c
+++ b/drivers/memstick/core/ms_block.c
@@ -15,7 +15,7 @@
 #define pr_fmt(fmt) DRIVER_NAME ": " fmt
 
 #include <linux/module.h>
-#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
 #include <linux/memstick.h>
 #include <linux/idr.h>
 #include <linux/hdreg.h>
@@ -1873,69 +1873,65 @@ static void msb_io_work(struct work_struct *work)
        struct msb_data *msb = container_of(work, struct msb_data, io_work);
        int page, error, len;
        sector_t lba;
-       unsigned long flags;
        struct scatterlist *sg = msb->prealloc_sg;
+       struct request *req;
 
        dbg_verbose("IO: work started");
 
        while (1) {
-               spin_lock_irqsave(&msb->q_lock, flags);
+               spin_lock_irq(&msb->q_lock);
 
                if (msb->need_flush_cache) {
                        msb->need_flush_cache = false;
-                       spin_unlock_irqrestore(&msb->q_lock, flags);
+                       spin_unlock_irq(&msb->q_lock);
                        msb_cache_flush(msb);
                        continue;
                }
 
-               if (!msb->req) {
-                       msb->req = blk_fetch_request(msb->queue);
-                       if (!msb->req) {
-                               dbg_verbose("IO: no more requests exiting");
-                               spin_unlock_irqrestore(&msb->q_lock, flags);
-                               return;
-                       }
+               req = msb->req;
+               if (!req) {
+                       dbg_verbose("IO: no more requests exiting");
+                       spin_unlock_irq(&msb->q_lock);
+                       return;
                }
 
-               spin_unlock_irqrestore(&msb->q_lock, flags);
-
-               /* If card was removed meanwhile */
-               if (!msb->req)
-                       return;
+               spin_unlock_irq(&msb->q_lock);
 
                /* process the request */
                dbg_verbose("IO: processing new request");
-               blk_rq_map_sg(msb->queue, msb->req, sg);
+               blk_rq_map_sg(msb->queue, req, sg);
 
-               lba = blk_rq_pos(msb->req);
+               lba = blk_rq_pos(req);
 
                sector_div(lba, msb->page_size / 512);
                page = sector_div(lba, msb->pages_in_block);
 
                if (rq_data_dir(msb->req) == READ)
                        error = msb_do_read_request(msb, lba, page, sg,
-                               blk_rq_bytes(msb->req), &len);
+                               blk_rq_bytes(req), &len);
                else
                        error = msb_do_write_request(msb, lba, page, sg,
-                               blk_rq_bytes(msb->req), &len);
-
-               spin_lock_irqsave(&msb->q_lock, flags);
+                               blk_rq_bytes(req), &len);
 
-               if (len)
-                       if (!__blk_end_request(msb->req, BLK_STS_OK, len))
-                               msb->req = NULL;
+               if (len && !blk_update_request(req, BLK_STS_OK, len)) {
+                       __blk_mq_end_request(req, BLK_STS_OK);
+                       spin_lock_irq(&msb->q_lock);
+                       msb->req = NULL;
+                       spin_unlock_irq(&msb->q_lock);
+               }
 
                if (error && msb->req) {
                        blk_status_t ret = errno_to_blk_status(error);
+
                        dbg_verbose("IO: ending one sector of the request with error");
-                       if (!__blk_end_request(msb->req, ret, msb->page_size))
-                               msb->req = NULL;
+                       blk_mq_end_request(req, ret);
+                       spin_lock_irq(&msb->q_lock);
+                       msb->req = NULL;
+                       spin_unlock_irq(&msb->q_lock);
                }
 
                if (msb->req)
                        dbg_verbose("IO: request still pending");
-
-               spin_unlock_irqrestore(&msb->q_lock, flags);
        }
 }
 
@@ -2002,29 +1998,40 @@ static int msb_bd_getgeo(struct block_device *bdev,
        return 0;
 }
 
-static void msb_submit_req(struct request_queue *q)
+static blk_status_t msb_queue_rq(struct blk_mq_hw_ctx *hctx,
+                                const struct blk_mq_queue_data *bd)
 {
-       struct memstick_dev *card = q->queuedata;
+       struct memstick_dev *card = hctx->queue->queuedata;
        struct msb_data *msb = memstick_get_drvdata(card);
-       struct request *req = NULL;
+       struct request *req = bd->rq;
 
        dbg_verbose("Submit request");
 
+       spin_lock_irq(&msb->q_lock);
+
        if (msb->card_dead) {
                dbg("Refusing requests on removed card");
 
                WARN_ON(!msb->io_queue_stopped);
 
-               while ((req = blk_fetch_request(q)) != NULL)
-                       __blk_end_request_all(req, BLK_STS_IOERR);
-               return;
+               spin_unlock_irq(&msb->q_lock);
+               blk_mq_start_request(req);
+               return BLK_STS_IOERR;
        }
 
-       if (msb->req)
-               return;
+       if (msb->req) {
+               spin_unlock_irq(&msb->q_lock);
+               return BLK_STS_DEV_RESOURCE;
+       }
+
+       blk_mq_start_request(req);
+       msb->req = req;
 
        if (!msb->io_queue_stopped)
                queue_work(msb->io_queue, &msb->io_work);
+
+       spin_unlock_irq(&msb->q_lock);
+       return BLK_STS_OK;
 }
 
 static int msb_check_card(struct memstick_dev *card)
@@ -2040,21 +2047,20 @@ static void msb_stop(struct memstick_dev *card)
 
        dbg("Stopping all msblock IO");
 
+       blk_mq_stop_hw_queues(msb->queue);
        spin_lock_irqsave(&msb->q_lock, flags);
-       blk_stop_queue(msb->queue);
        msb->io_queue_stopped = true;
        spin_unlock_irqrestore(&msb->q_lock, flags);
 
        del_timer_sync(&msb->cache_flush_timer);
        flush_workqueue(msb->io_queue);
 
+       spin_lock_irqsave(&msb->q_lock, flags);
        if (msb->req) {
-               spin_lock_irqsave(&msb->q_lock, flags);
-               blk_requeue_request(msb->queue, msb->req);
+               blk_mq_requeue_request(msb->req, false);
                msb->req = NULL;
-               spin_unlock_irqrestore(&msb->q_lock, flags);
        }
-
+       spin_unlock_irqrestore(&msb->q_lock, flags);
 }
 
 static void msb_start(struct memstick_dev *card)
@@ -2077,9 +2083,7 @@ static void msb_start(struct memstick_dev *card)
        msb->need_flush_cache = true;
        msb->io_queue_stopped = false;
 
-       spin_lock_irqsave(&msb->q_lock, flags);
-       blk_start_queue(msb->queue);
-       spin_unlock_irqrestore(&msb->q_lock, flags);
+       blk_mq_start_hw_queues(msb->queue);
 
        queue_work(msb->io_queue, &msb->io_work);
 
@@ -2092,10 +2096,15 @@ static const struct block_device_operations msb_bdops = {
        .owner   = THIS_MODULE
 };
 
+static const struct blk_mq_ops msb_mq_ops = {
+       .queue_rq       = msb_queue_rq,
+};
+
 /* Registers the block device */
 static int msb_init_disk(struct memstick_dev *card)
 {
        struct msb_data *msb = memstick_get_drvdata(card);
+       struct blk_mq_tag_set *set = NULL;
        int rc;
        unsigned long capacity;
 
@@ -2112,9 +2121,11 @@ static int msb_init_disk(struct memstick_dev *card)
                goto out_release_id;
        }
 
-       msb->queue = blk_init_queue(msb_submit_req, &msb->q_lock);
-       if (!msb->queue) {
-               rc = -ENOMEM;
+       msb->queue = blk_mq_init_sq_queue(&msb->tag_set, &msb_mq_ops, 2,
+                                               BLK_MQ_F_SHOULD_MERGE);
+       if (IS_ERR(msb->queue)) {
+               rc = PTR_ERR(msb->queue);
+               msb->queue = NULL;
                goto out_put_disk;
        }
 
@@ -2202,12 +2213,13 @@ static void msb_remove(struct memstick_dev *card)
        /* Take care of unhandled + new requests from now on */
        spin_lock_irqsave(&msb->q_lock, flags);
        msb->card_dead = true;
-       blk_start_queue(msb->queue);
        spin_unlock_irqrestore(&msb->q_lock, flags);
+       blk_mq_start_hw_queues(msb->queue);
 
        /* Remove the disk */
        del_gendisk(msb->disk);
        blk_cleanup_queue(msb->queue);
+       blk_mq_free_tag_set(&msb->tag_set);
        msb->queue = NULL;
 
        mutex_lock(&msb_disk_lock);

diff --git a/drivers/memstick/core/ms_block.h b/drivers/memstick/core/ms_block.h
index 53962c3..9ba84e0 100644 (file)
--- a/drivers/memstick/core/ms_block.h
+++ b/drivers/memstick/core/ms_block.h
@@ -152,6 +152,7 @@ struct msb_data {
        struct gendisk                  *disk;
        struct request_queue            *queue;
        spinlock_t                      q_lock;
+       struct blk_mq_tag_set           tag_set;
        struct hd_geometry              geometry;
        struct attribute_group          attr_group;
        struct request                  *req;