[Xen-devel] [PATCH 2/6] block: xen-blkback: use API provided by xenbus module to map rings

[David Vrabel <david.vrabel@xxxxxxxxxx>]

From: David Vrabel <david.vrabel@xxxxxxxxxx>

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

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 drivers/block/xen-blkback/common.h |    5 +--
 drivers/block/xen-blkback/xenbus.c |   55 +++++------------------------------
 2 files changed, 9 insertions(+), 51 deletions(-)

diff --git a/drivers/block/xen-blkback/common.h 
b/drivers/block/xen-blkback/common.h
index 9e40b28..65ef268 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;
+       struct page             *blk_ring_page;
        /* 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 3f129b4..7e21ef4 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 +129,30 @@ 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_page(blkif->be->dev, shared_page,
+                                  &blkif->blk_ring_page);
+       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 = page_address(blkif->blk_ring_page);
                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 = page_address(blkif->blk_ring_page);
                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 = page_address(blkif->blk_ring_page);
                BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, 
PAGE_SIZE);
                break;
        }
@@ -201,8 +164,7 @@ 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_page(blkif->be->dev, blkif->blk_ring_page);
                blkif->blk_rings.common.sring = NULL;
                return err;
        }
@@ -228,8 +190,7 @@ 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_page(blkif->be->dev, blkif->blk_ring_page);
                blkif->blk_rings.common.sring = NULL;
        }
 }
-- 
1.7.2.5


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