[Qemu-devel] [PULL 15/32] qcow2: Let inc_refcounts() resize the reftable

[Kevin Wolf <kwolf@redhat.com>]

From: Max Reitz <mreitz@redhat.com>

Now that the refcount table can be passed around by reference, do that
for inc_refcounts() (and subsequently check_refcounts_l1() and
check_refcounts_l2()) and use it for resizing it when a cluster after
the image end is encountered.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-refcount.c | 57 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 22 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 6001c85..d653124 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1083,8 +1083,8 @@ fail:
  */
 static int inc_refcounts(BlockDriverState *bs,
                          BdrvCheckResult *res,
-                         uint16_t *refcount_table,
-                         int64_t refcount_table_size,
+                         uint16_t **refcount_table,
+                         int64_t *refcount_table_size,
                          int64_t offset, int64_t size)
 {
     BDRVQcowState *s = bs->opaque;
@@ -1099,17 +1099,30 @@ static int inc_refcounts(BlockDriverState *bs,
     for(cluster_offset = start; cluster_offset <= last;
         cluster_offset += s->cluster_size) {
         k = cluster_offset >> s->cluster_bits;
-        if (k >= refcount_table_size) {
-            fprintf(stderr, "Warning: cluster offset=0x%" PRIx64 " is after "
-                "the end of the image file, can't properly check refcounts.\n",
-                cluster_offset);
-            res->check_errors++;
-        } else {
-            if (++refcount_table[k] == 0) {
-                fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
-                    "\n", cluster_offset);
-                res->corruptions++;
+        if (k >= *refcount_table_size) {
+            int64_t old_refcount_table_size = *refcount_table_size;
+            uint16_t *new_refcount_table;
+
+            *refcount_table_size = k + 1;
+            new_refcount_table = g_try_realloc(*refcount_table,
+                                               *refcount_table_size *
+                                               sizeof(**refcount_table));
+            if (!new_refcount_table) {
+                *refcount_table_size = old_refcount_table_size;
+                res->check_errors++;
+                return -ENOMEM;
             }
+            *refcount_table = new_refcount_table;
+
+            memset(*refcount_table + old_refcount_table_size, 0,
+                   (*refcount_table_size - old_refcount_table_size) *
+                   sizeof(**refcount_table));
+        }
+
+        if (++(*refcount_table)[k] == 0) {
+            fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
+                    "\n", cluster_offset);
+            res->corruptions++;
         }
     }
 
@@ -1130,7 +1143,7 @@ enum {
  * error occurred.
  */
 static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
-    uint16_t *refcount_table, int64_t refcount_table_size, int64_t l2_offset,
+    uint16_t **refcount_table, int64_t *refcount_table_size, int64_t l2_offset,
     int flags)
 {
     BDRVQcowState *s = bs->opaque;
@@ -1248,8 +1261,8 @@ fail:
  */
 static int check_refcounts_l1(BlockDriverState *bs,
                               BdrvCheckResult *res,
-                              uint16_t *refcount_table,
-                              int64_t refcount_table_size,
+                              uint16_t **refcount_table,
+                              int64_t *refcount_table_size,
                               int64_t l1_table_offset, int l1_size,
                               int flags)
 {
@@ -1586,7 +1599,7 @@ static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res,
         }
 
         if (offset != 0) {
-            ret = inc_refcounts(bs, res, *refcount_table, *nb_clusters,
+            ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
                                 offset, s->cluster_size);
             if (ret < 0) {
                 return ret;
@@ -1619,7 +1632,7 @@ static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res,
                                sizeof(**refcount_table));
                     }
                     (*refcount_table)[cluster]--;
-                    ret = inc_refcounts(bs, res, *refcount_table, *nb_clusters,
+                    ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
                                         new_offset, s->cluster_size);
                     if (ret < 0) {
                         return ret;
@@ -1655,14 +1668,14 @@ static int calculate_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
     }
 
     /* header */
-    ret = inc_refcounts(bs, res, *refcount_table, *nb_clusters,
+    ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
                         0, s->cluster_size);
     if (ret < 0) {
         return ret;
     }
 
     /* current L1 table */
-    ret = check_refcounts_l1(bs, res, *refcount_table, *nb_clusters,
+    ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
                              s->l1_table_offset, s->l1_size, CHECK_FRAG_INFO);
     if (ret < 0) {
         return ret;
@@ -1671,20 +1684,20 @@ static int calculate_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
     /* snapshots */
     for (i = 0; i < s->nb_snapshots; i++) {
         sn = s->snapshots + i;
-        ret = check_refcounts_l1(bs, res, *refcount_table, *nb_clusters,
+        ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
                                  sn->l1_table_offset, sn->l1_size, 0);
         if (ret < 0) {
             return ret;
         }
     }
-    ret = inc_refcounts(bs, res, *refcount_table, *nb_clusters,
+    ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
                         s->snapshots_offset, s->snapshots_size);
     if (ret < 0) {
         return ret;
     }
 
     /* refcount data */
-    ret = inc_refcounts(bs, res, *refcount_table, *nb_clusters,
+    ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
                         s->refcount_table_offset,
                         s->refcount_table_size * sizeof(uint64_t));
     if (ret < 0) {
-- 
1.8.3.1