On 2014-10-21 at 12:16, Max Reitz wrote:
On 2014-10-21 at 11:59, Kevin Wolf wrote:
Am 20.10.2014 um 16:35 hat Max Reitz geschrieben:
Because the old refcount structure will be leaked after having rebuilt
it, we need to recalculate the refcounts and run a leak-fixing
operation
afterwards (if leaks should be fixed at all).
Signed-off-by: Max Reitz <mre...@redhat.com>
Reviewed-by: Benoît Canet <benoit.ca...@nodalink.com>
---
block/qcow2-refcount.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 75e726b..3730be2 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1956,12 +1956,47 @@ int qcow2_check_refcounts(BlockDriverState
*bs, BdrvCheckResult *res,
nb_clusters);
if (rebuild && (fix & BDRV_FIX_ERRORS)) {
+ BdrvCheckResult old_res = *res;
+
fprintf(stderr, "Rebuilding refcount structure\n");
ret = rebuild_refcount_structure(bs, res, &refcount_table,
&nb_clusters);
if (ret < 0) {
goto fail;
}
+
+ res->corruptions = 0;
+ res->leaks = 0;
+
+ /* Because the old reftable has been exchanged for a new
one the
+ * references have to be recalculated */
+ rebuild = false;
+ memset(refcount_table, 0, nb_clusters * sizeof(uint16_t));
+ ret = calculate_refcounts(bs, res, 0, &rebuild,
&refcount_table,
+ &nb_clusters);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ if (fix & BDRV_FIX_LEAKS) {
+ /* The old refcount structures are now leaked, fix it;
the result
+ * can be ignored */
+ pre_compare_res = *res;
I would prefer using another local variable here. At the first sight
it's not quite clear which references to pre_compare_res correspond to
which state.
Why not.
+ compare_refcounts(bs, res, BDRV_FIX_LEAKS, &rebuild,
+ &highest_cluster, refcount_table,
nb_clusters);
+ if (rebuild) {
+ fprintf(stderr, "ERROR rebuilt refcount structure
is still "
+ "broken\n");
+ }
+ *res = pre_compare_res;
+ }
+
+ if (res->corruptions < old_res.corruptions) {
+ res->corruptions_fixed += old_res.corruptions -
res->corruptions;
+ }
+ if (res->leaks < old_res.leaks) {
+ res->leaks_fixed += old_res.leaks - res->leaks;
+ }
For these numbers to be accurate, don't we need to run
compare_refcounts() unconditionally and only make BDRV_FIX_LEAKS
conditional?
Actually, there is no difference, because at the point of this patch,
you cannot use BDRV_FIX_ERRORS without BDRV_FIX_LEAKS. But it'd be
more correct, right.
Wait, it would not be more correct. The result of the
compare_refcounts() call inside of the "if (fix & BDRV_FIX_LEAKS)"
conditional block is ignored, its only purpose is to fix leaks resulting
from rebuild_refcount_structure().
So the question is whether we should discard the result of that
compare_refcounts() call. I think we should. Its sole purpose is to fix
leaks due to the rebuilt refcount structures, and qemu-img will double
check anyway.
Max
Thanks,
Max
Now that I've read the rest of the series, comparing res and old_res
actually makes sense, so maybe it's not necessary to introduce a
Qcow2CheckResult.
} else if (fix) {
if (rebuild) {
fprintf(stderr, "ERROR need to rebuild refcount
structures\n");
--
2.1.2
Kevin
