src/patches/suse-2.6.27.25/patches.xen/xen-blktap-write-barriers

   1 From: kwolf@suse.de
   2 Subject: blktap: Write Barriers
   3 Patch-mainline: obsolete
   4
   5 --- sle11-2009-04-20.orig/drivers/xen/blktap/blktap.c   2009-04-20 11:40:25.000000000 +0200
   6 +++ sle11-2009-04-20/drivers/xen/blktap/blktap.c        2009-04-20 11:41:45.000000000 +0200
   7 @@ -1321,6 +1321,9 @@ static int do_block_io_op(blkif_t *blkif
   8                         dispatch_rw_block_io(blkif, &req, pending_req);
   9                         break;
  10
  11 +               case BLKIF_OP_WRITE_BARRIER:
  12 +                       /* TODO Some counter? */
  13 +                       /* Fall through */
  14                 case BLKIF_OP_WRITE:
  15                         blkif->st_wr_req++;
  16                         dispatch_rw_block_io(blkif, &req, pending_req);
  17 @@ -1352,7 +1355,7 @@ static void dispatch_rw_block_io(blkif_t
  18                                  pending_req_t *pending_req)
  19  {
  20         extern void ll_rw_block(int rw, int nr, struct buffer_head * bhs[]);
  21 -       int op, operation = (req->operation == BLKIF_OP_WRITE) ? WRITE : READ;
  22 +       int op, operation;
  23         struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST*2];
  24         unsigned int nseg;
  25         int ret, i, nr_sects = 0;
  26 @@ -1364,6 +1367,21 @@ static void dispatch_rw_block_io(blkif_t
  27         uint16_t mmap_idx = pending_req->mem_idx;
  28         struct mm_struct *mm;
  29
  30 +       switch (req->operation) {
  31 +       case BLKIF_OP_READ:
  32 +               operation = READ;
  33 +               break;
  34 +       case BLKIF_OP_WRITE:
  35 +               operation = WRITE;
  36 +               break;
  37 +       case BLKIF_OP_WRITE_BARRIER:
  38 +               operation = WRITE_BARRIER;
  39 +               break;
  40 +       default:
  41 +               operation = 0; /* make gcc happy */
  42 +               BUG();
  43 +       }
  44 +
  45         if (blkif->dev_num < 0 || blkif->dev_num > MAX_TAP_DEV)
  46                 goto fail_response;
  47
  48 @@ -1402,7 +1420,7 @@ static void dispatch_rw_block_io(blkif_t
  49
  50         pending_req->blkif     = blkif;
  51         pending_req->id        = req->id;
  52 -       pending_req->operation = operation;
  53 +       pending_req->operation = req->operation;
  54         pending_req->status    = BLKIF_RSP_OKAY;
  55         pending_req->nr_pages  = nseg;
  56         op = 0;
  57 @@ -1420,7 +1438,7 @@ static void dispatch_rw_block_io(blkif_t
  58                 kvaddr = idx_to_kaddr(mmap_idx, pending_idx, i);
  59
  60                 flags = GNTMAP_host_map;
  61 -               if (operation == WRITE)
  62 +               if (operation != READ)
  63                         flags |= GNTMAP_readonly;
  64                 gnttab_set_map_op(&map[op], kvaddr, flags,
  65                                   req->seg[i].gref, blkif->domid);
  66 @@ -1437,7 +1455,7 @@ static void dispatch_rw_block_io(blkif_t
  67
  68                         flags = GNTMAP_host_map | GNTMAP_application_map
  69                                 | GNTMAP_contains_pte;
  70 -                       if (operation == WRITE)
  71 +                       if (operation != READ)
  72                                 flags |= GNTMAP_readonly;
  73                         gnttab_set_map_op(&map[op], ptep, flags,
  74                                           req->seg[i].gref, blkif->domid);
  75 --- sle11-2009-04-20.orig/drivers/xen/blktap/xenbus.c   2008-09-15 15:10:39.000000000 +0200
  76 +++ sle11-2009-04-20/drivers/xen/blktap/xenbus.c        2008-11-10 12:14:32.000000000 +0100
  77 @@ -395,7 +395,28 @@ static void connect(struct backend_info
  78         int err;
  79
  80         struct xenbus_device *dev = be->dev;
  81 +       struct xenbus_transaction xbt;
  82
  83 +       /* Write feature-barrier to xenstore */
  84 +again:
  85 +       err = xenbus_transaction_start(&xbt);
  86 +       if (err) {
  87 +               xenbus_dev_fatal(dev, err, "starting transaction");
  88 +               return;
  89 +       }
  90 +
  91 +       err = xenbus_printf(xbt, dev->nodename, "feature-barrier",  "1");
  92 +       if (err) {
  93 +               xenbus_dev_fatal(dev, err, "writing feature-barrier");
  94 +               xenbus_transaction_end(xbt, 1);
  95 +               return;
  96 +       }
  97 +
  98 +       err = xenbus_transaction_end(xbt, 0);
  99 +       if (err == -EAGAIN)
 100 +               goto again;
 101 +
 102 +       /* Switch state */
 103         err = xenbus_switch_state(dev, XenbusStateConnected);
 104         if (err)
 105                 xenbus_dev_fatal(dev, err, "switching to Connected state",