2010-07-07 11:12:45 +00:00
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From: kwolf@suse.de
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Subject: blktap: Write Barriers
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Patch-mainline: obsolete
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2011-04-19 20:09:59 +00:00
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--- head-2011-02-17.orig/drivers/xen/blktap/blktap.c 2011-02-28 14:15:27.000000000 +0100
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+++ head-2011-02-17/drivers/xen/blktap/blktap.c 2011-02-28 14:21:49.000000000 +0100
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@@ -1374,6 +1374,9 @@ static int do_block_io_op(blkif_t *blkif
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2010-07-07 11:12:45 +00:00
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dispatch_rw_block_io(blkif, &req, pending_req);
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break;
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+ case BLKIF_OP_WRITE_BARRIER:
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+ /* TODO Some counter? */
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+ /* Fall through */
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case BLKIF_OP_WRITE:
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blkif->st_wr_req++;
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dispatch_rw_block_io(blkif, &req, pending_req);
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2011-04-19 20:09:59 +00:00
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@@ -1432,7 +1435,7 @@ static void dispatch_rw_block_io(blkif_t
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2010-07-07 11:12:45 +00:00
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2011-04-19 20:09:59 +00:00
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/* Check that number of segments is sane. */
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nseg = req->nr_segments;
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- if ( unlikely(nseg == 0) ||
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+ if (unlikely(nseg == 0 && req->operation != BLKIF_OP_WRITE_BARRIER) ||
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unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) ) {
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WPRINTK("Bad number of segments in request (%d)\n", nseg);
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goto fail_response;
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@@ -1458,8 +1461,13 @@ static void dispatch_rw_block_io(blkif_t
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pending_req->nr_pages = nseg;
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flags = GNTMAP_host_map;
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- if (req->operation == BLKIF_OP_WRITE)
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2010-07-07 11:12:45 +00:00
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+ switch (req->operation) {
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+ case BLKIF_OP_WRITE:
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+ case BLKIF_OP_WRITE_BARRIER:
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2011-04-19 20:09:59 +00:00
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flags |= GNTMAP_readonly;
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2010-07-07 11:12:45 +00:00
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+ break;
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+ }
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+
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op = 0;
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2011-04-19 20:09:59 +00:00
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mm = info->mm;
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if (!xen_feature(XENFEAT_auto_translated_physmap))
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@@ -1622,6 +1630,7 @@ static void dispatch_rw_block_io(blkif_t
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blkif->st_rd_sect += nr_sects;
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break;
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case BLKIF_OP_WRITE:
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+ case BLKIF_OP_WRITE_BARRIER:
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blkif->st_wr_sect += nr_sects;
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break;
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}
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--- head-2011-02-17.orig/drivers/xen/blktap/xenbus.c 2010-11-25 10:57:14.000000000 +0100
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+++ head-2011-02-17/drivers/xen/blktap/xenbus.c 2010-11-25 10:57:21.000000000 +0100
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@@ -418,7 +418,28 @@ static void connect(struct backend_info
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2010-07-07 11:12:45 +00:00
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int err;
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struct xenbus_device *dev = be->dev;
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+ struct xenbus_transaction xbt;
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+ /* Write feature-barrier to xenstore */
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+again:
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+ err = xenbus_transaction_start(&xbt);
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+ if (err) {
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+ xenbus_dev_fatal(dev, err, "starting transaction");
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+ return;
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+ }
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+
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+ err = xenbus_printf(xbt, dev->nodename, "feature-barrier", "1");
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+ if (err) {
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+ xenbus_dev_fatal(dev, err, "writing feature-barrier");
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+ xenbus_transaction_end(xbt, 1);
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+ return;
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+ }
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+
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+ err = xenbus_transaction_end(xbt, 0);
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+ if (err == -EAGAIN)
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+ goto again;
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+
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+ /* Switch state */
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err = xenbus_switch_state(dev, XenbusStateConnected);
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if (err)
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xenbus_dev_fatal(dev, err, "switching to Connected state",
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