[for-4.2,07/13] qcow2: Add qcow2_check_fix_snapshot_table()

Commit Message

Max Reitz July 30, 2019, 5:25 p.m. UTC

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 <[e-mail]>
---
 block/qcow2.h          |  3 +++
 block/qcow2-snapshot.c | 25 +++++++++++++++++++++++++
 block/qcow2.c          |  9 ++++++++-
 3 files changed, 36 insertions(+), 1 deletion(-)

Comments

Eric Blake July 30, 2019, 6:54 p.m. UTC | #1

On 7/30/19 12:25 PM, Max Reitz wrote:
> 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 <[e-mail]>
> ---

Reviewed-by: Eric Blake <[e-mail]>

Patch

diff --git a/block/qcow2.h b/block/qcow2.h
index 50c7eefb5b..6823c37e82 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -715,6 +715,9 @@  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 cbc6d699b6..58609b6ea4 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -379,6 +379,31 @@  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 2983a7795a..ac94cc7807 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -594,13 +594,20 @@  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;
     }