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[Xen-devel] [PATCH 02/10] xen/blkfront: drop legacy block layer support



As Christoph suggested, remove the legacy support similar to most
drivers coverted (virtio, mtip, and nvme).

Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
 drivers/block/xen-blkfront.c | 167 +++++++++----------------------------------
 1 file changed, 32 insertions(+), 135 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 13e6178..3589436 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -135,7 +135,6 @@ struct blkfront_info
        unsigned int max_indirect_segments;
        int is_ready;
        struct blk_mq_tag_set tag_set;
-       int feature_multiqueue;
 };
 
 static unsigned int nr_minors;
@@ -606,54 +605,6 @@ static inline bool blkif_request_flush_invalid(struct 
request *req,
                 !(info->feature_flush & REQ_FUA)));
 }
 
-/*
- * do_blkif_request
- *  read a block; request is in a request queue
- */
-static void do_blkif_request(struct request_queue *rq)
-{
-       struct blkfront_info *info = NULL;
-       struct request *req;
-       int queued;
-
-       pr_debug("Entered do_blkif_request\n");
-
-       queued = 0;
-
-       while ((req = blk_peek_request(rq)) != NULL) {
-               info = req->rq_disk->private_data;
-
-               if (RING_FULL(&info->ring))
-                       goto wait;
-
-               blk_start_request(req);
-
-               if (blkif_request_flush_invalid(req, info)) {
-                       __blk_end_request_all(req, -EOPNOTSUPP);
-                       continue;
-               }
-
-               pr_debug("do_blk_req %p: cmd %p, sec %lx, "
-                        "(%u/%u) [%s]\n",
-                        req, req->cmd, (unsigned long)blk_rq_pos(req),
-                        blk_rq_cur_sectors(req), blk_rq_sectors(req),
-                        rq_data_dir(req) ? "write" : "read");
-
-               if (blkif_queue_request(req)) {
-                       blk_requeue_request(rq, req);
-wait:
-                       /* Avoid pointless unplugs. */
-                       blk_stop_queue(rq);
-                       break;
-               }
-
-               queued++;
-       }
-
-       if (queued != 0)
-               flush_requests(info);
-}
-
 static int blk_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
                        const struct blk_mq_queue_data *qd)
 {
@@ -697,27 +648,21 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 
sector_size,
        struct request_queue *rq;
        struct blkfront_info *info = gd->private_data;
 
-       if (info->feature_multiqueue) {
-               memset(&info->tag_set, 0, sizeof(info->tag_set));
-               info->tag_set.ops = &blkfront_mq_ops;
-               info->tag_set.nr_hw_queues = 1;
-               info->tag_set.queue_depth =  BLK_RING_SIZE;
-               info->tag_set.numa_node = NUMA_NO_NODE;
-               info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
-               info->tag_set.cmd_size = 0;
-               info->tag_set.driver_data = info;
-
-               if (blk_mq_alloc_tag_set(&info->tag_set))
-                       return -1;
-               rq = blk_mq_init_queue(&info->tag_set);
-               if (IS_ERR(rq)) {
-                       blk_mq_free_tag_set(&info->tag_set);
-                       return -1;
-               }
-       } else {
-               rq = blk_init_queue(do_blkif_request, &info->io_lock);
-               if (rq == NULL)
-                       return -1;
+       memset(&info->tag_set, 0, sizeof(info->tag_set));
+       info->tag_set.ops = &blkfront_mq_ops;
+       info->tag_set.nr_hw_queues = 1;
+       info->tag_set.queue_depth =  BLK_RING_SIZE;
+       info->tag_set.numa_node = NUMA_NO_NODE;
+       info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
+       info->tag_set.cmd_size = 0;
+       info->tag_set.driver_data = info;
+
+       if (blk_mq_alloc_tag_set(&info->tag_set))
+               return -1;
+       rq = blk_mq_init_queue(&info->tag_set);
+       if (IS_ERR(rq)) {
+               blk_mq_free_tag_set(&info->tag_set);
+               return -1;
        }
 
        queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
@@ -954,10 +899,7 @@ static void xlvbd_release_gendisk(struct blkfront_info 
*info)
        spin_lock_irqsave(&info->io_lock, flags);
 
        /* No more blkif_request(). */
-       if (info->feature_multiqueue)
-               blk_mq_stop_hw_queues(info->rq);
-       else
-               blk_stop_queue(info->rq);
+       blk_mq_stop_hw_queues(info->rq);
 
        /* No more gnttab callback work. */
        gnttab_cancel_free_callback(&info->callback);
@@ -980,18 +922,11 @@ static void xlvbd_release_gendisk(struct blkfront_info 
*info)
        info->gd = NULL;
 }
 
+/* Called with info->io_lock holded */
 static void kick_pending_request_queues(struct blkfront_info *info)
 {
-       if (!RING_FULL(&info->ring)) {
-               if (info->feature_multiqueue) {
-                       blk_mq_start_stopped_hw_queues(info->rq, true);
-               } else {
-                       /* Re-enable calldowns. */
-                       blk_start_queue(info->rq);
-                       /* Kick things off immediately. */
-                       do_blkif_request(info->rq);
-               }
-       }
+       if (!RING_FULL(&info->ring))
+               blk_mq_start_stopped_hw_queues(info->rq, true);
 }
 
 static void blkif_restart_queue(struct work_struct *work)
@@ -1015,12 +950,8 @@ static void blkif_free(struct blkfront_info *info, int 
suspend)
        info->connected = suspend ?
                BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
        /* No more blkif_request(). */
-       if (info->rq) {
-               if (info->feature_multiqueue)
-                       blk_mq_stop_hw_queues(info->rq);
-               else
-                       blk_stop_queue(info->rq);
-       }
+       if (info->rq)
+               blk_mq_stop_hw_queues(info->rq);
 
        /* Remove all persistent grants */
        if (!list_empty(&info->grants)) {
@@ -1204,7 +1135,6 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
        RING_IDX i, rp;
        unsigned long flags;
        struct blkfront_info *info = (struct blkfront_info *)dev_id;
-       int error;
 
        spin_lock_irqsave(&info->io_lock, flags);
 
@@ -1245,40 +1175,37 @@ static irqreturn_t blkif_interrupt(int irq, void 
*dev_id)
                        continue;
                }
 
-               error = req->errors = (bret->status == BLKIF_RSP_OKAY) ? 0 : 
-EIO;
+               req->errors = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
                switch (bret->operation) {
                case BLKIF_OP_DISCARD:
                        if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
                                struct request_queue *rq = info->rq;
                                printk(KERN_WARNING "blkfront: %s: %s op 
failed\n",
                                           info->gd->disk_name, 
op_name(bret->operation));
-                               error = req->errors = -EOPNOTSUPP;
+                               req->errors = -EOPNOTSUPP;
                                info->feature_discard = 0;
                                info->feature_secdiscard = 0;
                                queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
                                queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
                        }
-                       if (info->feature_multiqueue)
-                               blk_mq_complete_request(req);
-                       else
-                               __blk_end_request_all(req, error);
+                       blk_mq_complete_request(req);
                        break;
                case BLKIF_OP_FLUSH_DISKCACHE:
                case BLKIF_OP_WRITE_BARRIER:
                        if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
                                printk(KERN_WARNING "blkfront: %s: %s op 
failed\n",
                                       info->gd->disk_name, 
op_name(bret->operation));
-                               error = req->errors = -EOPNOTSUPP;
+                               req->errors = -EOPNOTSUPP;
                        }
                        if (unlikely(bret->status == BLKIF_RSP_ERROR &&
                                     info->shadow[id].req.u.rw.nr_segments == 
0)) {
                                printk(KERN_WARNING "blkfront: %s: empty %s op 
failed\n",
                                       info->gd->disk_name, 
op_name(bret->operation));
-                               error = req->errors = -EOPNOTSUPP;
+                               req->errors = -EOPNOTSUPP;
                        }
-                       if (unlikely(error)) {
-                               if (error == -EOPNOTSUPP)
-                                       error = req->errors = 0;
+                       if (unlikely(req->errors)) {
+                               if (req->errors == -EOPNOTSUPP)
+                                       req->errors = 0;
                                info->feature_flush = 0;
                                xlvbd_flush(info);
                        }
@@ -1289,10 +1216,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
                                dev_dbg(&info->xbdev->dev, "Bad return from 
blkdev data "
                                        "request: %x\n", bret->status);
 
-                       if (info->feature_multiqueue)
-                               blk_mq_complete_request(req);
-                       else
-                               __blk_end_request_all(req, error);
+                       blk_mq_complete_request(req);
                        break;
                default:
                        BUG();
@@ -1592,28 +1516,6 @@ static int blkif_recover(struct blkfront_info *info)
 
        kfree(copy);
 
-       /*
-        * Empty the queue, this is important because we might have
-        * requests in the queue with more segments than what we
-        * can handle now.
-        */
-       spin_lock_irq(&info->io_lock);
-       while ((req = blk_fetch_request(info->rq)) != NULL) {
-               if (req->cmd_flags &
-                   (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
-                       list_add(&req->queuelist, &requests);
-                       continue;
-               }
-               merge_bio.head = req->bio;
-               merge_bio.tail = req->biotail;
-               bio_list_merge(&bio_list, &merge_bio);
-               req->bio = NULL;
-               if (req->cmd_flags & (REQ_FLUSH | REQ_FUA))
-                       pr_alert("diskcache flush request found!\n");
-               __blk_put_request(info->rq, req);
-       }
-       spin_unlock_irq(&info->io_lock);
-
        xenbus_switch_state(info->xbdev, XenbusStateConnected);
 
        spin_lock_irq(&info->io_lock);
@@ -1628,13 +1530,9 @@ static int blkif_recover(struct blkfront_info *info)
                /* Requeue pending requests (flush or discard) */
                list_del_init(&req->queuelist);
                BUG_ON(req->nr_phys_segments > segs);
-               if (info->feature_multiqueue)
-                       blk_mq_requeue_request(req);
-               else
-                       blk_requeue_request(info->rq, req);
+               blk_mq_requeue_request(req);
        }
-       if (info->feature_multiqueue)
-               blk_mq_kick_requeue_list(info->rq);
+       blk_mq_kick_requeue_list(info->rq);
        spin_unlock_irq(&info->io_lock);
 
        while ((bio = bio_list_pop(&bio_list)) != NULL) {
@@ -1954,7 +1852,6 @@ static void blkfront_connect(struct blkfront_info *info)
                return;
        }
 
-       info->feature_multiqueue = 1;
        err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
                                  physical_sector_size);
        if (err) {
-- 
1.8.3.1


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