[Xen-devel] [PATCH 2/3] xen-blkfront: introduce blkif_set_queue_limits()

[Bob Liu <bob.liu@xxxxxxxxxx>]

blk_mq_update_nr_hw_queues() reset all queue limits to default which it's not
as xen-blkfront expected, introducing blkif_set_queue_limits() to reset limits
with initial correct values.

Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
 drivers/block/xen-blkfront.c | 91 ++++++++++++++++++++++++--------------------
 1 file changed, 50 insertions(+), 41 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 032fc94..10f46a8 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -189,6 +189,8 @@ struct blkfront_info
        struct mutex mutex;
        struct xenbus_device *xbdev;
        struct gendisk *gd;
+       u16 sector_size;
+       unsigned int physical_sector_size;
        int vdevice;
        blkif_vdev_t handle;
        enum blkif_state connected;
@@ -913,9 +915,45 @@ static struct blk_mq_ops blkfront_mq_ops = {
        .map_queue = blk_mq_map_queue,
 };
 
+static void blkif_set_queue_limits(struct blkfront_info *info)
+{
+       struct request_queue *rq = info->rq;
+       struct gendisk *gd = info->gd;
+       unsigned int segments = info->max_indirect_segments ? :
+                               BLKIF_MAX_SEGMENTS_PER_REQUEST;
+
+       queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
+
+       if (info->feature_discard) {
+               queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
+               blk_queue_max_discard_sectors(rq, get_capacity(gd));
+               rq->limits.discard_granularity = info->discard_granularity;
+               rq->limits.discard_alignment = info->discard_alignment;
+               if (info->feature_secdiscard)
+                       queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
+       }
+
+       /* Hard sector size and max sectors impersonate the equiv. hardware. */
+       blk_queue_logical_block_size(rq, info->sector_size);
+       blk_queue_physical_block_size(rq, info->physical_sector_size);
+       blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
+
+       /* Each segment in a request is up to an aligned page in size. */
+       blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
+       blk_queue_max_segment_size(rq, PAGE_SIZE);
+
+       /* Ensure a merged request will fit in a single I/O ring slot. */
+       blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
+
+       /* Make sure buffer addresses are sector-aligned. */
+       blk_queue_dma_alignment(rq, 511);
+
+       /* Make sure we don't use bounce buffers. */
+       blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
+}
+
 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
-                               unsigned int physical_sector_size,
-                               unsigned int segments)
+                               unsigned int physical_sector_size)
 {
        struct request_queue *rq;
        struct blkfront_info *info = gd->private_data;
@@ -947,37 +985,11 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 
sector_size,
        }
 
        rq->queuedata = info;
-       queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
-
-       if (info->feature_discard) {
-               queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
-               blk_queue_max_discard_sectors(rq, get_capacity(gd));
-               rq->limits.discard_granularity = info->discard_granularity;
-               rq->limits.discard_alignment = info->discard_alignment;
-               if (info->feature_secdiscard)
-                       queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
-       }
-
-       /* Hard sector size and max sectors impersonate the equiv. hardware. */
-       blk_queue_logical_block_size(rq, sector_size);
-       blk_queue_physical_block_size(rq, physical_sector_size);
-       blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
-
-       /* Each segment in a request is up to an aligned page in size. */
-       blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
-       blk_queue_max_segment_size(rq, PAGE_SIZE);
-
-       /* Ensure a merged request will fit in a single I/O ring slot. */
-       blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
-
-       /* Make sure buffer addresses are sector-aligned. */
-       blk_queue_dma_alignment(rq, 511);
-
-       /* Make sure we don't use bounce buffers. */
-       blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
-
-       gd->queue = rq;
-
+       info->rq = gd->queue = rq;
+       info->gd = gd;
+       info->sector_size = sector_size;
+       info->physical_sector_size = physical_sector_size;
+       blkif_set_queue_limits(info);
        return 0;
 }
 
@@ -1142,16 +1154,11 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
        gd->driverfs_dev = &(info->xbdev->dev);
        set_capacity(gd, capacity);
 
-       if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
-                                info->max_indirect_segments ? :
-                                BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
+       if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
                del_gendisk(gd);
                goto release;
        }
 
-       info->rq = gd->queue;
-       info->gd = gd;
-
        xlvbd_flush(info);
 
        if (vdisk_info & VDISK_READONLY)
@@ -2132,9 +2139,11 @@ static int blkfront_resume(struct xenbus_device *dev)
                return err;
 
        err = talk_to_blkback(dev, info);
-       if (!err)
+       if (!err) {
                blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
-
+               /* Reset limits changed by blk-mq. */
+               blkif_set_queue_limits(info);
+       }
        /*
         * We have to wait for the backend to switch to
         * connected state, since we want to read which
-- 
2.7.4


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