qcow2: Update qcow2_truncate() to support L2 slices

The qcow2_truncate() code is mostly independent from whether
we're using L2 slices or full L2 tables, but in full and
falloc preallocation modes new L2 tables are allocated using
qcow2_alloc_cluster_link_l2().  Therefore the code needs to be
modified to ensure that all nb_clusters that are processed in each
call can be allocated with just one L2 slice.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: 1fd7d272b5e7b66254a090b74cf2bed1cc334c0e.1517840877.git.berto@igalia.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

diff --git a/block/qcow2.c b/block/qcow2.c
index ba8d71c72d55c1449584960bbdbbe38feea98786..953254a004f223b1d58e17c81a049b3b89b420a6 100644 (file)
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3262,9 +3262,9 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset,
         host_offset = allocation_start;
         guest_offset = old_length;
         while (nb_new_data_clusters) {
-            int64_t guest_cluster = guest_offset >> s->cluster_bits;
-            int64_t nb_clusters = MIN(nb_new_data_clusters,
-                                      s->l2_size - guest_cluster % s->l2_size);
+            int64_t nb_clusters = MIN(
+                nb_new_data_clusters,
+                s->l2_slice_size - offset_to_l2_slice_index(s, guest_offset));
             QCowL2Meta allocation = {
                 .offset       = guest_offset,
                 .alloc_offset = host_offset,