block: xen-blkback: use API provided by xenbus module to map rings

The xenbus module provides xenbus_map_ring_valloc() and
xenbus_map_ring_vfree().  Use these to map the ring pages granted by
the frontend.

Acked-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

2 files changed, 8 insertions, 51 deletions

diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 00c57c90e2d6..7ec0e8896a78 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -139,7 +139,7 @@ struct xen_blkif {
         /* Comms information. */
         enum blkif_protocol     blk_protocol;
         union blkif_back_rings  blk_rings;
-        struct vm_struct        *blk_ring_area;
+        void                    *blk_ring;
         /* The VBD attached to this interface. */
         struct xen_vbd          vbd;
         /* Back pointer to the backend_info. */
@@ -163,9 +163,6 @@ struct xen_blkif {
         int                     st_wr_sect;
 
         wait_queue_head_t       waiting_to_free;
-
-        grant_handle_t          shmem_handle;
-        grant_ref_t             shmem_ref;
 };
 
 
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 5fd2010f7d2b..69233dd42212 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -120,38 +120,6 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
         return blkif;
 }
 
-static int map_frontend_page(struct xen_blkif *blkif, unsigned long shared_page)
-{
-        struct gnttab_map_grant_ref op;
-
-        gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
-                          GNTMAP_host_map, shared_page, blkif->domid);
-
-        if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
-                BUG();
-
-        if (op.status) {
-                DPRINTK("Grant table operation failure !\n");
-                return op.status;
-        }
-
-        blkif->shmem_ref = shared_page;
-        blkif->shmem_handle = op.handle;
-
-        return 0;
-}
-
-static void unmap_frontend_page(struct xen_blkif *blkif)
-{
-        struct gnttab_unmap_grant_ref op;
-
-        gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
-                            GNTMAP_host_map, blkif->shmem_handle);
-
-        if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
-                BUG();
-}
-
 static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
                          unsigned int evtchn)
 {
@@ -161,35 +129,29 @@ static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
         if (blkif->irq)
                 return 0;
 
-        blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE);
-        if (!blkif->blk_ring_area)
-                return -ENOMEM;
-
-        err = map_frontend_page(blkif, shared_page);
-        if (err) {
-                free_vm_area(blkif->blk_ring_area);
+        err = xenbus_map_ring_valloc(blkif->be->dev, shared_page, &blkif->blk_ring);
+        if (err < 0)
                 return err;
-        }
 
         switch (blkif->blk_protocol) {
         case BLKIF_PROTOCOL_NATIVE:
         {
                 struct blkif_sring *sring;
-                sring = (struct blkif_sring *)blkif->blk_ring_area->addr;
+                sring = (struct blkif_sring *)blkif->blk_ring;
                 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
                 break;
         }
         case BLKIF_PROTOCOL_X86_32:
         {
                 struct blkif_x86_32_sring *sring_x86_32;
-                sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring_area->addr;
+                sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring;
                 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
                 break;
         }
         case BLKIF_PROTOCOL_X86_64:
         {
                 struct blkif_x86_64_sring *sring_x86_64;
-                sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr;
+                sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring;
                 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
                 break;
         }
@@ -201,8 +163,7 @@ static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
                                                     xen_blkif_be_int, 0,
                                                     "blkif-backend", blkif);
         if (err < 0) {
-                unmap_frontend_page(blkif);
-                free_vm_area(blkif->blk_ring_area);
+                xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
                 blkif->blk_rings.common.sring = NULL;
                 return err;
         }
@@ -228,8 +189,7 @@ static void xen_blkif_disconnect(struct xen_blkif *blkif)
         }
 
         if (blkif->blk_rings.common.sring) {
-                unmap_frontend_page(blkif);
-                free_vm_area(blkif->blk_ring_area);
+                xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
                 blkif->blk_rings.common.sring = NULL;
         }
 }