xen/blkback: Move processing of BLKIF_OP_DISCARD from dispatch_rw_block_io

.. and move it to its own function that will deal with the
discard operation.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 24 insertions, 30 deletions

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 9d2261b02f24..b058de7825f5 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -416,12 +416,16 @@ static int xen_blkbk_map(struct blkif_request *req,
         return ret;
 }
 
-static void xen_blk_discard(struct xen_blkif *blkif, struct blkif_request *req)
+static int dispatch_discard_io(struct xen_blkif *blkif,
+                                struct blkif_request *req)
 {
         int err = 0;
         int status = BLKIF_RSP_OKAY;
         struct block_device *bdev = blkif->vbd.bdev;
 
+        blkif->st_ds_req++;
+
+        xen_blkif_get(blkif);
         if (blkif->blk_backend_type == BLKIF_BACKEND_PHY) {
                 unsigned long secure = (blkif->vbd.discard_secure &&
                         (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
@@ -453,6 +457,8 @@ static void xen_blk_discard(struct xen_blkif *blkif, struct blkif_request *req)
                 status = BLKIF_RSP_ERROR;
 
         make_response(blkif, req->u.discard.id, req->operation, status);
+        xen_blkif_put(blkif);
+        return err;
 }
 
 static void xen_blk_drain_io(struct xen_blkif *blkif)
@@ -576,8 +582,11 @@ __do_block_io_op(struct xen_blkif *blkif)
 
                 /* Apply all sanity checks to /private copy/ of request. */
                 barrier();
-
-                if (dispatch_rw_block_io(blkif, &req, pending_req))
+                if (unlikely(req.operation == BLKIF_OP_DISCARD)) {
+                        free_req(pending_req);
+                        if (dispatch_discard_io(blkif, &req))
+                                break;
+                } else if (dispatch_rw_block_io(blkif, &req, pending_req))
                         break;
 
                 /* Yield point for this unbounded loop. */
@@ -636,24 +645,16 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
                 blkif->st_f_req++;
                 operation = WRITE_FLUSH;
                 break;
-        case BLKIF_OP_DISCARD:
-                blkif->st_ds_req++;
-                operation = REQ_DISCARD;
-                break;
         default:
                 operation = 0; /* make gcc happy */
                 goto fail_response;
                 break;
         }
 
-        if (unlikely(operation == REQ_DISCARD))
-                nseg = 0;
-        else
-                /* Check that the number of segments is sane. */
-                nseg = req->u.rw.nr_segments;
+        /* Check that the number of segments is sane. */
+        nseg = req->u.rw.nr_segments;
 
-        if (unlikely(nseg == 0 && operation != WRITE_FLUSH &&
-                                operation != REQ_DISCARD) ||
+        if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
             unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
                 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n",
                          nseg);
@@ -714,7 +715,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
          * the hypercall to unmap the grants - that is all done in
          * xen_blkbk_unmap.
          */
-        if (nseg && xen_blkbk_map(req, pending_req, seg))
+        if (xen_blkbk_map(req, pending_req, seg))
                 goto fail_flush;
 
         /*
@@ -746,23 +747,16 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
 
         /* This will be hit if the operation was a flush or discard. */
         if (!bio) {
-                BUG_ON(operation != WRITE_FLUSH && operation != REQ_DISCARD);
+                BUG_ON(operation != WRITE_FLUSH);
 
-                if (operation == WRITE_FLUSH) {
-                        bio = bio_alloc(GFP_KERNEL, 0);
-                        if (unlikely(bio == NULL))
-                                goto fail_put_bio;
+                bio = bio_alloc(GFP_KERNEL, 0);
+                if (unlikely(bio == NULL))
+                        goto fail_put_bio;
 
-                        biolist[nbio++] = bio;
-                        bio->bi_bdev    = preq.bdev;
-                        bio->bi_private = pending_req;
-                        bio->bi_end_io  = end_block_io_op;
-                } else if (operation == REQ_DISCARD) {
-                        xen_blk_discard(blkif, req);
-                        xen_blkif_put(blkif);
-                        free_req(pending_req);
-                        return 0;
-                }
+                biolist[nbio++] = bio;
+                bio->bi_bdev    = preq.bdev;
+                bio->bi_private = pending_req;
+                bio->bi_end_io  = end_block_io_op;
         }
 
         /*