nbd/server: Fix dirty bitmap logic regression

In my hurry to fix a build failure, I introduced a logic bug.
The assertion conditional is backwards, meaning that qemu will
now abort instead of reporting dirty bitmap status.

The bug can only be tickled by an NBD client using an exported
dirty bitmap (which is still an experimental QMP command), so
it's not the end of the world for supported usage (and neither
'make check' nor qemu-iotests fails); but it also shows that we
really want qemu-io support for reading dirty bitmaps if only
so that I can add iotests coverage to prevent future
brown-bag-of-shame events like this one.

Fixes: 45eb6fb6
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180622153509.375130-1-eblake@redhat.com>

diff --git a/nbd/server.c b/nbd/server.c
index 50ac8bfafc685741e22d49de9d01c63c36bc0f1e..e52b76bd1a4a7a344154c36c1585f10d406ea967 100644 (file)
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1977,7 +1977,7 @@ static unsigned int bitmap_to_extents(BdrvDirtyBitmap *bitmap, uint64_t offset,
 
     bdrv_dirty_bitmap_unlock(bitmap);
 
-    assert(offset > end);
+    assert(offset < end);
     *length = end - offset;
     return i;
 }