qcow2: Employ metadata overlap checks

The pre-write overlap check function is now called before most of the
qcow2 writes (aborting it on collision or other error).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 0caac9055f..e7e601301a 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -189,6 +189,15 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
         return ret;
     }
 
+    /* The snapshot list position has not yet been updated, so these clusters
+     * must indeed be completely free */
+    ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, offset,
+                                        s->snapshots_size);
+    if (ret < 0) {
+        return ret;
+    }
+
+
     /* Write all snapshots to the new list */
     for(i = 0; i < s->nb_snapshots; i++) {
         sn = s->snapshots + i;
@@ -363,6 +372,12 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
         l1_table[i] = cpu_to_be64(s->l1_table[i]);
     }
 
+    ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
+            sn->l1_table_offset, s->l1_size * sizeof(uint64_t));
+    if (ret < 0) {
+        goto fail;
+    }
+
     ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
                       s->l1_size * sizeof(uint64_t));
     if (ret < 0) {
@@ -475,6 +490,13 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
         goto fail;
     }
 
+    ret = qcow2_pre_write_overlap_check(bs,
+            QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L1,
+            s->l1_table_offset, cur_l1_bytes);
+    if (ret < 0) {
+        goto fail;
+    }
+
     ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, sn_l1_table,
                            cur_l1_bytes);
     if (ret < 0) {