[Qemu-devel] [PATCH 3/3] qcow2: Support for fixing refcount inconsistencies

[Kevin Wolf <kwolf@redhat.com>]

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-refcount.c |   27 +++++++++++++++++++++++++--
 block/qcow2.c          |    6 +-----
 block/qcow2.h          |    3 ++-
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 443c021..6a9a672 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1122,7 +1122,8 @@ fail:
  * Returns 0 if no errors are found, the number of errors in case the image is
  * detected as corrupted, and -errno when an internal error occurred.
  */
-int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res)
+int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
+                          BdrvCheckMode fix)
 {
     BDRVQcowState *s = bs->opaque;
     int64_t size;
@@ -1205,9 +1206,31 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res)
 
         refcount2 = refcount_table[i];
         if (refcount1 != refcount2) {
+
+            /* Check if we're allowed to fix the mismatch */
+            int *num_fixed = NULL;
+            if (refcount1 > refcount2 && (fix & BDRV_FIX_LEAKS)) {
+                num_fixed = &res->leaks_fixed;
+            } else if (refcount1 < refcount2 && (fix & BDRV_FIX_ERRORS)) {
+                num_fixed = &res->corruptions_fixed;
+            }
+
             fprintf(stderr, "%s cluster %d refcount=%d reference=%d\n",
-                   refcount1 < refcount2 ? "ERROR" : "Leaked",
+                   num_fixed != NULL     ? "Repairing" :
+                   refcount1 < refcount2 ? "ERROR" :
+                                           "Leaked",
                    i, refcount1, refcount2);
+
+            if (num_fixed) {
+                ret = update_refcount(bs, i << s->cluster_bits, 1,
+                                      refcount2 - refcount1);
+                if (ret >= 0) {
+                    (*num_fixed)++;
+                    continue;
+                }
+            }
+
+            /* And if we couldn't, print an error */
             if (refcount1 < refcount2) {
                 res->corruptions++;
             } else {
diff --git a/block/qcow2.c b/block/qcow2.c
index 23cc920..cc751d2 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1511,11 +1511,7 @@ static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result,
                        BdrvCheckMode fix)
 {
-    if (fix) {
-        return -ENOTSUP;
-    }
-
-    return qcow2_check_refcounts(bs, result);
+    return qcow2_check_refcounts(bs, result, fix);
 }
 
 #if 0
diff --git a/block/qcow2.h b/block/qcow2.h
index 9b7b2d6..5fb7f61 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -275,7 +275,8 @@ void qcow2_free_any_clusters(BlockDriverState *bs,
 int qcow2_update_snapshot_refcount(BlockDriverState *bs,
     int64_t l1_table_offset, int l1_size, int addend);
 
-int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res);
+int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
+                          BdrvCheckMode fix);
 
 /* qcow2-cluster.c functions */
 int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size);
-- 
1.7.6.5