src/patches/60044_xen-blktap-write-barriers.patch1

   1 From: kwolf@suse.de
   2 Subject: blktap: Write Barriers
   3 Patch-mainline: obsolete
   4
   5 Index: head-2008-11-10/drivers/xen/blktap/blktap.c
   6 ===================================================================
   7 --- head-2008-11-10.orig/drivers/xen/blktap/blktap.c    2008-11-10 12:10:23.000000000 +0100
   8 +++ head-2008-11-10/drivers/xen/blktap/blktap.c 2008-11-10 12:14:32.000000000 +0100
   9 @@ -1324,6 +1324,9 @@ static int do_block_io_op(blkif_t *blkif
  10                         dispatch_rw_block_io(blkif, &req, pending_req);
  11                         break;
  12
  13 +               case BLKIF_OP_WRITE_BARRIER:
  14 +                       /* TODO Some counter? */
  15 +                       /* Fall through */
  16                 case BLKIF_OP_WRITE:
  17                         blkif->st_wr_req++;
  18                         dispatch_rw_block_io(blkif, &req, pending_req);
  19 @@ -1355,7 +1358,7 @@ static void dispatch_rw_block_io(blkif_t
  20                                  pending_req_t *pending_req)
  21  {
  22         extern void ll_rw_block(int rw, int nr, struct buffer_head * bhs[]);
  23 -       int op, operation = (req->operation == BLKIF_OP_WRITE) ? WRITE : READ;
  24 +       int op, operation;
  25         struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST*2];
  26         unsigned int nseg;
  27         int ret, i, nr_sects = 0;
  28 @@ -1366,6 +1369,21 @@ static void dispatch_rw_block_io(blkif_t
  29         uint16_t mmap_idx = pending_req->mem_idx;
  30         struct mm_struct *mm;
  31
  32 +       switch (req->operation) {
  33 +       case BLKIF_OP_READ:
  34 +               operation = READ;
  35 +               break;
  36 +       case BLKIF_OP_WRITE:
  37 +               operation = WRITE;
  38 +               break;
  39 +       case BLKIF_OP_WRITE_BARRIER:
  40 +               operation = WRITE_BARRIER;
  41 +               break;
  42 +       default:
  43 +               operation = 0; /* make gcc happy */
  44 +               BUG();
  45 +       }
  46 +
  47         if (blkif->dev_num < 0 || blkif->dev_num > MAX_TAP_DEV)
  48                 goto fail_response;
  49
  50 @@ -1404,7 +1422,7 @@ static void dispatch_rw_block_io(blkif_t
  51
  52         pending_req->blkif     = blkif;
  53         pending_req->id        = req->id;
  54 -       pending_req->operation = operation;
  55 +       pending_req->operation = req->operation;
  56         pending_req->status    = BLKIF_RSP_OKAY;
  57         pending_req->nr_pages  = nseg;
  58         op = 0;
  59 @@ -1421,7 +1439,7 @@ static void dispatch_rw_block_io(blkif_t
  60                 kvaddr = idx_to_kaddr(mmap_idx, pending_idx, i);
  61
  62                 flags = GNTMAP_host_map;
  63 -               if (operation == WRITE)
  64 +               if (operation != READ)
  65                         flags |= GNTMAP_readonly;
  66                 gnttab_set_map_op(&map[op], kvaddr, flags,
  67                                   req->seg[i].gref, blkif->domid);
  68 @@ -1438,7 +1456,7 @@ static void dispatch_rw_block_io(blkif_t
  69
  70                         flags = GNTMAP_host_map | GNTMAP_application_map
  71                                 | GNTMAP_contains_pte;
  72 -                       if (operation == WRITE)
  73 +                       if (operation != READ)
  74                                 flags |= GNTMAP_readonly;
  75                         gnttab_set_map_op(&map[op], ptep, flags,
  76                                           req->seg[i].gref, blkif->domid);
  77 Index: head-2008-11-10/drivers/xen/blktap/xenbus.c
  78 ===================================================================
  79 --- head-2008-11-10.orig/drivers/xen/blktap/xenbus.c    2008-11-10 12:14:29.000000000 +0100
  80 +++ head-2008-11-10/drivers/xen/blktap/xenbus.c 2008-11-10 12:14:32.000000000 +0100
  81 @@ -395,7 +395,28 @@ static void connect(struct backend_info
  82         int err;
  83
  84         struct xenbus_device *dev = be->dev;
  85 +       struct xenbus_transaction xbt;
  86
  87 +       /* Write feature-barrier to xenstore */
  88 +again:
  89 +       err = xenbus_transaction_start(&xbt);
  90 +       if (err) {
  91 +               xenbus_dev_fatal(dev, err, "starting transaction");
  92 +               return;
  93 +       }
  94 +
  95 +       err = xenbus_printf(xbt, dev->nodename, "feature-barrier",  "1");
  96 +       if (err) {
  97 +               xenbus_dev_fatal(dev, err, "writing feature-barrier");
  98 +               xenbus_transaction_end(xbt, 1);
  99 +               return;
 100 +       }
 101 +
 102 +       err = xenbus_transaction_end(xbt, 0);
 103 +       if (err == -EAGAIN)
 104 +               goto again;
 105 +
 106 +       /* Switch state */
 107         err = xenbus_switch_state(dev, XenbusStateConnected);
 108         if (err)
 109                 xenbus_dev_fatal(dev, err, "switching to Connected state",