[Qemu-devel] [PATCH 1/2] qcow2: Make size_to_clusters() return int64_t

[Max Reitz <mreitz@redhat.com>]

Sadly, some images may have more clusters than what can be represented
using a plain int. We should be prepared for that case (in
qcow2_check_refcounts() we actually were trying to catch that case, but
since size_to_clusters() truncated the returned value, that check never
did anything useful).

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/qcow2-cluster.c | 20 +++++++++++---------
 block/qcow2.h         |  2 +-
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 2975b83..a34f0b1 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -473,8 +473,8 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
     unsigned int l2_index;
     uint64_t l1_index, l2_offset, *l2_table;
     int l1_bits, c;
-    unsigned int index_in_cluster, nb_clusters;
-    uint64_t nb_available, nb_needed;
+    unsigned int index_in_cluster;
+    uint64_t nb_available, nb_needed, nb_clusters;
     int ret;
 
     index_in_cluster = (offset >> 9) & (s->cluster_sectors - 1);
@@ -837,10 +837,10 @@ err:
  * write, but require COW to be performed (this includes yet unallocated space,
  * which must copy from the backing file)
  */
-static int count_cow_clusters(BDRVQcow2State *s, int nb_clusters,
+static int count_cow_clusters(BDRVQcow2State *s, uint64_t nb_clusters,
     uint64_t *l2_table, int l2_index)
 {
-    int i;
+    uint64_t i;
 
     for (i = 0; i < nb_clusters; i++) {
         uint64_t l2_entry = be64_to_cpu(l2_table[l2_index + i]);
@@ -960,7 +960,7 @@ static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
     int l2_index;
     uint64_t cluster_offset;
     uint64_t *l2_table;
-    unsigned int nb_clusters;
+    uint64_t nb_clusters;
     unsigned int keep_clusters;
     int ret;
 
@@ -1426,7 +1426,7 @@ int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
  * clusters.
  */
 static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
-    unsigned int nb_clusters, enum qcow2_discard_type type, bool full_discard)
+    uint64_t nb_clusters, enum qcow2_discard_type type, bool full_discard)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t *l2_table;
@@ -1441,6 +1441,7 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
 
     /* Limit nb_clusters to one L2 table */
     nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+    assert(nb_clusters <= INT_MAX);
 
     for (i = 0; i < nb_clusters; i++) {
         uint64_t old_l2_entry;
@@ -1503,7 +1504,7 @@ int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t end_offset;
-    unsigned int nb_clusters;
+    uint64_t nb_clusters;
     int ret;
 
     end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS);
@@ -1545,7 +1546,7 @@ fail:
  * clusters.
  */
 static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
-    unsigned int nb_clusters)
+    uint64_t nb_clusters)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t *l2_table;
@@ -1560,6 +1561,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
 
     /* Limit nb_clusters to one L2 table */
     nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+    assert(nb_clusters <= INT_MAX);
 
     for (i = 0; i < nb_clusters; i++) {
         uint64_t old_offset;
@@ -1584,7 +1586,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
 int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors)
 {
     BDRVQcow2State *s = bs->opaque;
-    unsigned int nb_clusters;
+    uint64_t nb_clusters;
     int ret;
 
     /* The zero flag is only supported by version 3 and newer */
diff --git a/block/qcow2.h b/block/qcow2.h
index 61f1b57..ce292a0 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -415,7 +415,7 @@ static inline int64_t offset_into_cluster(BDRVQcow2State *s, int64_t offset)
     return offset & (s->cluster_size - 1);
 }
 
-static inline int size_to_clusters(BDRVQcow2State *s, int64_t size)
+static inline int64_t size_to_clusters(BDRVQcow2State *s, int64_t size)
 {
     return (size + (s->cluster_size - 1)) >> s->cluster_bits;
 }
-- 
2.5.1