dma-helpers: Fix too long qiov
If the size of the scatter/gather list isn't a multiple of 512, the
number of sectors for the block layer request is rounded down, resulting
in a qiov that doesn't match the request length. Truncate the qiov to the
new length of the request.
This fixes the IDE qtest case /x86_64/ide/bmdma/short_prdt.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/util/iov.c b/util/iov.c
index 2b4f46d..24566c8 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -550,3 +550,16 @@
return total;
}
+
+void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes)
+{
+ size_t total;
+ unsigned int niov = qiov->niov;
+
+ assert(qiov->size >= bytes);
+ total = iov_discard_back(qiov->iov, &niov, bytes);
+ assert(total == bytes);
+
+ qiov->niov = niov;
+ qiov->size -= bytes;
+}
