commit df702c9b4c1d049b12d7cf2f2ee607ff32f766cb
author Paolo Bonzini <pbonzini@redhat.com> Mon Jan 14 16:26:58 2013 +0100
committer Stefan Hajnoczi <stefanha@redhat.com> Tue Jan 15 10:03:48 2013 +0100
tree 98d268644fff7121bc9063488d9dcadea4fa7f53
parent 501378c3af16e8e83a9dd500c11e594f4d1dbe79

block: clear dirty bitmap when discarding

Note that resetting bits in the dirty bitmap is done _before_ actually
processing the request.  Writes, instead, set bits after the request
is completed.

This way, when there are concurrent write and discard requests, the
outcome will always be that the blocks are marked dirty.  This scenario
should never happen, but it is safer to do it this way.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block.c

diff --git a/block.c b/block.c
index 4a90dd1..6fa7c90 100644
--- a/block.c
+++ b/block.c
@@ -4170,7 +4170,13 @@
         return -EIO;
     } else if (bs->read_only) {
         return -EROFS;
-    } else if (bs->drv->bdrv_co_discard) {
+    }
+
+    if (bs->dirty_bitmap) {
+        set_dirty_bitmap(bs, sector_num, nb_sectors, 0);
+    }
+
+    if (bs->drv->bdrv_co_discard) {
         return bs->drv->bdrv_co_discard(bs, sector_num, nb_sectors);
     } else if (bs->drv->bdrv_aio_discard) {
         BlockDriverAIOCB *acb;