qcow2-refcount: Repair OFLAG_COPIED errors

Since the OFLAG_COPIED checks are now executed after the refcounts have
been repaired (if repairing), it is safe to assume that they are correct
but the OFLAG_COPIED flag may be not. Therefore, if its value differs
from what it should be (considering the according refcount), that
discrepancy can be repaired by correctly setting (or clearing that flag.

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

1 files changed, 52 insertions, 6 deletions

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index aa4b98d85a..2276b6f7f5 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1225,7 +1225,8 @@ fail:
  * been already detected and sufficiently signaled by the calling function
  * (qcow2_check_refcounts) by the time this function is called).
  */
-static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res)
+static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res,
+                              BdrvCheckMode fix)
 {
     BDRVQcowState *s = bs->opaque;
     uint64_t *l2_table = qemu_blockalign(bs, s->cluster_size);
@@ -1236,6 +1237,7 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res)
     for (i = 0; i < s->l1_size; i++) {
         uint64_t l1_entry = s->l1_table[i];
         uint64_t l2_offset = l1_entry & L1E_OFFSET_MASK;
+        bool l2_dirty = false;
 
         if (!l2_offset) {
             continue;
@@ -1247,10 +1249,24 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res)
             continue;
         }
         if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) {
-            fprintf(stderr, "ERROR OFLAG_COPIED L2 cluster: l1_index=%d "
+            fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d "
                     "l1_entry=%" PRIx64 " refcount=%d\n",
+                    fix & BDRV_FIX_ERRORS ? "Repairing" :
+                                            "ERROR",
                     i, l1_entry, refcount);
-            res->corruptions++;
+            if (fix & BDRV_FIX_ERRORS) {
+                s->l1_table[i] = refcount == 1
+                               ? l1_entry |  QCOW_OFLAG_COPIED
+                               : l1_entry & ~QCOW_OFLAG_COPIED;
+                ret = qcow2_write_l1_entry(bs, i);
+                if (ret < 0) {
+                    res->check_errors++;
+                    goto fail;
+                }
+                res->corruptions_fixed++;
+            } else {
+                res->corruptions++;
+            }
         }
 
         ret = bdrv_pread(bs->file, l2_offset, l2_table,
@@ -1275,13 +1291,43 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res)
                     continue;
                 }
                 if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
-                    fprintf(stderr, "ERROR OFLAG_COPIED data cluster: "
+                    fprintf(stderr, "%s OFLAG_COPIED data cluster: "
                             "l2_entry=%" PRIx64 " refcount=%d\n",
+                            fix & BDRV_FIX_ERRORS ? "Repairing" :
+                                                    "ERROR",
                             l2_entry, refcount);
-                    res->corruptions++;
+                    if (fix & BDRV_FIX_ERRORS) {
+                        l2_table[j] = cpu_to_be64(refcount == 1
+                                    ? l2_entry |  QCOW_OFLAG_COPIED
+                                    : l2_entry & ~QCOW_OFLAG_COPIED);
+                        l2_dirty = true;
+                        res->corruptions_fixed++;
+                    } else {
+                        res->corruptions++;
+                    }
                 }
             }
         }
+
+        if (l2_dirty) {
+            ret = qcow2_pre_write_overlap_check(bs,
+                    QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L2, l2_offset,
+                    s->cluster_size);
+            if (ret < 0) {
+                fprintf(stderr, "ERROR: Could not write L2 table; metadata "
+                        "overlap check failed: %s\n", strerror(-ret));
+                res->check_errors++;
+                goto fail;
+            }
+
+            ret = bdrv_pwrite(bs->file, l2_offset, l2_table, s->cluster_size);
+            if (ret < 0) {
+                fprintf(stderr, "ERROR: Could not write L2 table: %s\n",
+                        strerror(-ret));
+                res->check_errors++;
+                goto fail;
+            }
+        }
     }
 
     ret = 0;
@@ -1427,7 +1473,7 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
     }
 
     /* check OFLAG_COPIED */
-    ret = check_oflag_copied(bs, res);
+    ret = check_oflag_copied(bs, res, fix);
     if (ret < 0) {
         goto fail;
     }