[PULL 53/69] qcow2: Add qcow2_check_fix_snapshot_table()

[Max Reitz]

qcow2_check_read_snapshot_table() can perform consistency checks, but it
cannot fix everything.  Specifically, it cannot allocate new clusters,
because that should wait until the refcount structures are known to be
consistent (i.e., after qcow2_check_refcounts()).  Thus, it cannot call
qcow2_write_snapshots().

Do that in qcow2_check_fix_snapshot_table(), which is called after
qcow2_check_refcounts().

Currently, there is nothing that would set result->corruptions, so this
is a no-op.  A follow-up patch will change that.

Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Message-id: address@hidden
Signed-off-by: Max Reitz <address@hidden>
---
 block/qcow2.h          |  3 +++
 block/qcow2-snapshot.c | 25 +++++++++++++++++++++++++
 block/qcow2.c          |  9 ++++++++-
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/block/qcow2.h b/block/qcow2.h
index adb5c3bc28..601c2e4c82 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -721,6 +721,9 @@ int qcow2_write_snapshots(BlockDriverState *bs);
 int coroutine_fn qcow2_check_read_snapshot_table(BlockDriverState *bs,
                                                  BdrvCheckResult *result,
                                                  BdrvCheckMode fix);
+int coroutine_fn qcow2_check_fix_snapshot_table(BlockDriverState *bs,
+                                                BdrvCheckResult *result,
+                                                BdrvCheckMode fix);
 
 /* qcow2-cache.c functions */
 Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables,
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index d667bfd935..b526a8f819 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -380,6 +380,31 @@ int coroutine_fn 
qcow2_check_read_snapshot_table(BlockDriverState *bs,
     return 0;
 }
 
+int coroutine_fn qcow2_check_fix_snapshot_table(BlockDriverState *bs,
+                                                BdrvCheckResult *result,
+                                                BdrvCheckMode fix)
+{
+    BDRVQcow2State *s = bs->opaque;
+    int ret;
+
+    if (result->corruptions && (fix & BDRV_FIX_ERRORS)) {
+        qemu_co_mutex_unlock(&s->lock);
+        ret = qcow2_write_snapshots(bs);
+        qemu_co_mutex_lock(&s->lock);
+        if (ret < 0) {
+            result->check_errors++;
+            fprintf(stderr, "ERROR failed to update snapshot table: %s\n",
+                    strerror(-ret));
+            return ret;
+        }
+
+        result->corruptions_fixed += result->corruptions;
+        result->corruptions = 0;
+    }
+
+    return 0;
+}
+
 static void find_new_snapshot_id(BlockDriverState *bs,
                                  char *id_str, int id_str_size)
 {
diff --git a/block/qcow2.c b/block/qcow2.c
index b0026e8a9a..8d4f38ae74 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -597,13 +597,20 @@ static int coroutine_fn 
qcow2_co_check_locked(BlockDriverState *bs,
     memset(result, 0, sizeof(*result));
 
     ret = qcow2_check_read_snapshot_table(bs, &snapshot_res, fix);
-    qcow2_add_check_result(result, &snapshot_res, false);
     if (ret < 0) {
+        qcow2_add_check_result(result, &snapshot_res, false);
         return ret;
     }
 
     ret = qcow2_check_refcounts(bs, &refcount_res, fix);
     qcow2_add_check_result(result, &refcount_res, true);
+    if (ret < 0) {
+        qcow2_add_check_result(result, &snapshot_res, false);
+        return ret;
+    }
+
+    ret = qcow2_check_fix_snapshot_table(bs, &snapshot_res, fix);
+    qcow2_add_check_result(result, &snapshot_res, false);
     if (ret < 0) {
         return ret;
     }
-- 
2.21.0