xen/blkback: Shuffle code around (vbd_translate moved higher).

We take out the chunk of code dealing with mapping to the guest
of pages into the xen_blk_map_buf code. And we also move the
vbd_translate to be done much earlier.

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

diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
index f282463d7b5ce0f5d63938a5c02eccff4528a6d3..211b2005f963fffdb07b3a9cb2f913b5dd7362f4 100644 (file)
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -241,6 +241,10 @@ int blkif_schedule(void *arg)
        return 0;
 }
 
+struct seg_buf {
+       unsigned long buf;
+       unsigned int nsec;
+};
 /*
  * Unmap the grant references, and also remove the M2P over-rides
  * used in the 'pending_req'.
@@ -278,6 +282,62 @@ static void fast_flush_area(struct pending_req *req)
                }
        }
 }
+static int xen_blk_map_buf(struct blkif_request *req, struct pending_req *pending_req,
+                          struct seg_buf seg[])
+{
+       struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+       int i;
+       int nseg = req->nr_segments;
+       int ret = 0;
+       /* Fill out preq.nr_sects with proper amount of sectors, and setup
+        * assign map[..] with the PFN of the page in our domain with the
+        * corresponding grant reference for each page.
+        */
+       for (i = 0; i < nseg; i++) {
+               uint32_t flags;
+
+               flags = GNTMAP_host_map;
+               if (pending_req->operation != BLKIF_OP_READ)
+                       flags |= GNTMAP_readonly;
+               gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags,
+                                 req->u.rw.seg[i].gref, pending_req->blkif->domid);
+       }
+
+       ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg);
+       BUG_ON(ret);
+
+       /* Now swizzel the MFN in our domain with the MFN from the other domain
+        * so that when we access vaddr(pending_req,i) it has the contents of
+        * the page from the other domain.
+        */
+       for (i = 0; i < nseg; i++) {
+               if (unlikely(map[i].status != 0)) {
+                       DPRINTK("invalid buffer -- could not remap it\n");
+                       map[i].handle = BLKBACK_INVALID_HANDLE;
+                       ret |= 1;
+               }
+
+               pending_handle(pending_req, i) = map[i].handle;
+
+               if (ret)
+                       continue;
+
+               ret = m2p_add_override(PFN_DOWN(map[i].dev_bus_addr),
+                       blkbk->pending_page(pending_req, i), false);
+               if (ret) {
+                       printk(KERN_ALERT "Failed to install M2P override for"\
+                               " %lx (ret: %d)\n", (unsigned long)
+                               map[i].dev_bus_addr, ret);
+                       /* We could switch over to GNTTABOP_copy */
+                       continue;
+               }
+
+               seg[i].buf  = map[i].dev_bus_addr |
+                       (req->u.rw.seg[i].first_sect << 9);
+       }
+       return ret;
+}
+
 /*
  * Completion callback on the bio's. Called as bh->b_end_io()
  */
@@ -411,15 +471,12 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
                                 struct blkif_request *req,
                                 struct pending_req *pending_req)
 {
-       struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
        struct phys_req preq;
-       struct {
-               unsigned long buf; unsigned int nsec;
-       } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+       struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
        unsigned int nseg;
        struct bio *bio = NULL;
        struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST];
-       int ret, i, nbio = 0;
+       int i, nbio = 0;
        int operation;
        struct blk_plug plug;
        struct request_queue *q;
@@ -444,6 +501,7 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
        if (unlikely(nseg == 0 && operation != WRITE_BARRIER) ||
            unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
                DPRINTK("Bad number of segments in request (%d)\n", nseg);
+               /* Haven't submitted any bio's yet. */
                goto fail_response;
        }
 
@@ -456,77 +514,30 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
        pending_req->operation = req->operation;
        pending_req->status    = BLKIF_RSP_OKAY;
        pending_req->nr_pages  = nseg;
-
-       /* Fill out preq.nr_sects with proper amount of sectors, and setup
-        * assign map[..] with the PFN of the page in our domain with the
-        * corresponding grant reference for each page.
-        */
        for (i = 0; i < nseg; i++) {
-               uint32_t flags;
-
                seg[i].nsec = req->u.rw.seg[i].last_sect -
                        req->u.rw.seg[i].first_sect + 1;
                if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
                    (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect))
                        goto fail_response;
                preq.nr_sects += seg[i].nsec;
-
-               flags = GNTMAP_host_map;
-               if (operation != READ)
-                       flags |= GNTMAP_readonly;
-               gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags,
-                                 req->u.rw.seg[i].gref, blkif->domid);
        }
 
-       ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg);
-       BUG_ON(ret);
-
-       /* Now swizzel the MFN in our domain with the MFN from the other domain
-        * so that when we access vaddr(pending_req,i) it has the contents of
-        * the page from the other domain.
-        */
-       for (i = 0; i < nseg; i++) {
-               if (unlikely(map[i].status != 0)) {
-                       DPRINTK("invalid buffer -- could not remap it\n");
-                       map[i].handle = BLKBACK_INVALID_HANDLE;
-                       ret |= 1;
-               }
-
-               pending_handle(pending_req, i) = map[i].handle;
-
-               if (ret)
-                       continue;
-
-               ret = m2p_add_override(PFN_DOWN(map[i].dev_bus_addr),
-                       blkbk->pending_page(pending_req, i), false);
-               if (ret) {
-                       printk(KERN_ALERT "Failed to install M2P override for"\
-                               " %lx (ret: %d)\n", (unsigned long)
-                               map[i].dev_bus_addr, ret);
-                       /* We could switch over to GNTTABOP_copy */
-                       continue;
-               }
-
-               seg[i].buf  = map[i].dev_bus_addr |
-                       (req->u.rw.seg[i].first_sect << 9);
+       if (vbd_translate(&preq, blkif, operation) != 0) {
+               DPRINTK("access denied: %s of [%llu,%llu] on dev=%04x\n",
+                       operation == READ ? "read" : "write",
+                       preq.sector_number,
+                       preq.sector_number + preq.nr_sects, preq.dev);
+               goto fail_response;
        }
-
        /* If we have failed at this point, we need to undo the M2P override,
         * set gnttab_set_unmap_op on all of the grant references and perform
         * the hypercall to unmap the grants - that is all done in
         * fast_flush_area.
         */
-       if (ret)
+       if (xen_blk_map_buf(req, pending_req, seg))
                goto fail_flush;
 
-       if (vbd_translate(&preq, blkif, operation) != 0) {
-               DPRINTK("access denied: %s of [%llu,%llu] on dev=%04x\n",
-                       operation == READ ? "read" : "write",
-                       preq.sector_number,
-                       preq.sector_number + preq.nr_sects, preq.dev);
-               goto fail_flush;
-       }
-
        /* This corresponding blkif_put is done in __end_block_io_op */
        blkif_get(blkif);