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[Qemu-devel] [PATCH v3 03/22] qcow2: Use 64 bits for refcount values
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH v3 03/22] qcow2: Use 64 bits for refcount values |
Date: |
Thu, 20 Nov 2014 18:06:19 +0100 |
Refcounts may have a width of up to 64 bits, so qemu should use the same
width to represent refcount values internally.
Since for instance qcow2_get_refcount() signals an error by returning a
negative value, refcount values are generally signed to be able to
represent those error values correctly. This limits the maximum refcount
value supported by qemu to INT64_MAX (= 63 bits), as established in
"qcow2: Add two new fields to BDRVQcowState".
This limitation should have no implications in practice for normal valid
images. If the MSb in a 64 bit refcount value is set, we can safely
assume the value to be invalid (because reaching such high refcounts is
impossible due to other limitations of the qcow2 format).
Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
block/qcow2-cluster.c | 9 ++++++---
block/qcow2-refcount.c | 37 ++++++++++++++++++++-----------------
block/qcow2.h | 7 ++++---
3 files changed, 30 insertions(+), 23 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index df0b2c9..ab43902 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1640,7 +1640,7 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
for (i = 0; i < l1_size; i++) {
uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
bool l2_dirty = false;
- int l2_refcount;
+ int64_t l2_refcount;
if (!l2_offset) {
/* unallocated */
@@ -1696,14 +1696,17 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
}
if (l2_refcount > 1) {
+ int64_t ret64;
+
/* For shared L2 tables, set the refcount accordingly (it
is
* already 1 and needs to be l2_refcount) */
- ret = qcow2_update_cluster_refcount(bs,
+ ret64 = qcow2_update_cluster_refcount(bs,
offset >> s->cluster_bits, l2_refcount - 1,
QCOW2_DISCARD_OTHER);
- if (ret < 0) {
+ if (ret64 < 0) {
qcow2_free_clusters(bs, offset, s->cluster_size,
QCOW2_DISCARD_OTHER);
+ ret = ret64;
goto fail;
}
}
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 6016211..6e06531 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -91,14 +91,14 @@ static int load_refcount_block(BlockDriverState *bs,
* return value is the refcount of the cluster, negative values are -errno
* and indicate an error.
*/
-int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index)
+int64_t qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index)
{
BDRVQcowState *s = bs->opaque;
uint64_t refcount_table_index, block_index;
int64_t refcount_block_offset;
int ret;
uint16_t *refcount_block;
- uint16_t refcount;
+ int64_t refcount;
refcount_table_index = cluster_index >> s->refcount_block_bits;
if (refcount_table_index >= s->refcount_table_size)
@@ -556,9 +556,10 @@ static int QEMU_WARN_UNUSED_RESULT
update_refcount(BlockDriverState *bs,
for(cluster_offset = start; cluster_offset <= last;
cluster_offset += s->cluster_size)
{
- int block_index, refcount;
+ int block_index;
int64_t cluster_index = cluster_offset >> s->cluster_bits;
int64_t table_index = cluster_index >> s->refcount_block_bits;
+ int64_t refcount;
/* Load the refcount block and allocate it if needed */
if (table_index != old_table_index) {
@@ -634,10 +635,10 @@ fail:
* If the return value is non-negative, it is the new refcount of the cluster.
* If it is negative, it is -errno and indicates an error.
*/
-int qcow2_update_cluster_refcount(BlockDriverState *bs,
- int64_t cluster_index,
- int addend,
- enum qcow2_discard_type type)
+int64_t qcow2_update_cluster_refcount(BlockDriverState *bs,
+ int64_t cluster_index,
+ int addend,
+ enum qcow2_discard_type type)
{
BDRVQcowState *s = bs->opaque;
int ret;
@@ -663,7 +664,7 @@ static int64_t alloc_clusters_noref(BlockDriverState *bs,
uint64_t size)
{
BDRVQcowState *s = bs->opaque;
uint64_t i, nb_clusters;
- int refcount;
+ int64_t refcount;
nb_clusters = size_to_clusters(s, size);
retry:
@@ -722,7 +723,8 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t
offset,
BDRVQcowState *s = bs->opaque;
uint64_t cluster_index;
uint64_t i;
- int refcount, ret;
+ int64_t refcount;
+ int ret;
assert(nb_clusters >= 0);
if (nb_clusters == 0) {
@@ -878,8 +880,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
BDRVQcowState *s = bs->opaque;
uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2;
bool l1_allocated = false;
- int64_t old_offset, old_l2_offset;
- int i, j, l1_modified = 0, nb_csectors, refcount;
+ int64_t old_offset, old_l2_offset, refcount;
+ int i, j, l1_modified = 0, nb_csectors;
int ret;
l2_table = NULL;
@@ -1341,7 +1343,7 @@ static int check_oflag_copied(BlockDriverState *bs,
BdrvCheckResult *res,
BDRVQcowState *s = bs->opaque;
uint64_t *l2_table = qemu_blockalign(bs, s->cluster_size);
int ret;
- int refcount;
+ int64_t refcount;
int i, j;
for (i = 0; i < s->l1_size; i++) {
@@ -1360,7 +1362,7 @@ static int check_oflag_copied(BlockDriverState *bs,
BdrvCheckResult *res,
}
if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) {
fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d "
- "l1_entry=%" PRIx64 " refcount=%d\n",
+ "l1_entry=%" PRIx64 " refcount=%" PRId64 "\n",
fix & BDRV_FIX_ERRORS ? "Repairing" :
"ERROR",
i, l1_entry, refcount);
@@ -1403,7 +1405,7 @@ static int check_oflag_copied(BlockDriverState *bs,
BdrvCheckResult *res,
}
if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
fprintf(stderr, "%s OFLAG_COPIED data cluster: "
- "l2_entry=%" PRIx64 " refcount=%d\n",
+ "l2_entry=%" PRIx64 " refcount=%" PRId64 "\n",
fix & BDRV_FIX_ERRORS ? "Repairing" :
"ERROR",
l2_entry, refcount);
@@ -1628,8 +1630,8 @@ static void compare_refcounts(BlockDriverState *bs,
BdrvCheckResult *res,
uint16_t *refcount_table, int64_t nb_clusters)
{
BDRVQcowState *s = bs->opaque;
- int64_t i;
- int refcount1, refcount2, ret;
+ int64_t i, refcount1, refcount2;
+ int ret;
for (i = 0, *highest_cluster = 0; i < nb_clusters; i++) {
refcount1 = qcow2_get_refcount(bs, i);
@@ -1657,7 +1659,8 @@ static void compare_refcounts(BlockDriverState *bs,
BdrvCheckResult *res,
num_fixed = &res->corruptions_fixed;
}
- fprintf(stderr, "%s cluster %" PRId64 " refcount=%d
reference=%d\n",
+ fprintf(stderr, "%s cluster %" PRId64 " refcount=%" PRId64
+ " reference=%" PRId64 "\n",
num_fixed != NULL ? "Repairing" :
refcount1 < refcount2 ? "ERROR" :
"Leaked",
diff --git a/block/qcow2.h b/block/qcow2.h
index 4d8c902..0f8eb15 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -489,10 +489,11 @@ void qcow2_signal_corruption(BlockDriverState *bs, bool
fatal, int64_t offset,
int qcow2_refcount_init(BlockDriverState *bs);
void qcow2_refcount_close(BlockDriverState *bs);
-int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index);
+int64_t qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index);
-int qcow2_update_cluster_refcount(BlockDriverState *bs, int64_t cluster_index,
- int addend, enum qcow2_discard_type type);
+int64_t qcow2_update_cluster_refcount(BlockDriverState *bs,
+ int64_t cluster_index, int addend,
+ enum qcow2_discard_type type);
int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t size);
int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
--
1.9.3