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Re: [Qemu-devel] [PATCH] qcow2: use start_of_cluster() and offset_into_c


From: Fam Zheng
Subject: Re: [Qemu-devel] [PATCH] qcow2: use start_of_cluster() and offset_into_cluster() everywhere
Date: Thu, 05 Dec 2013 15:33:18 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1

On 2013年12月05日 14:32, Hu Tao wrote:
Signed-off-by: Hu Tao <address@hidden>
---
  block/qcow2-cluster.c  |  2 +-
  block/qcow2-refcount.c | 22 +++++++++++-----------
  2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 791083a..b54ad3c 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1401,7 +1401,7 @@ int qcow2_discard_clusters(BlockDriverState *bs, uint64_t 
offset,

      /* Round start up and end down */
      offset = align_offset(offset, s->cluster_size);
-    end_offset &= ~(s->cluster_size - 1);
+    end_offset = start_of_cluster(s, end_offset);

      if (offset > end_offset) {
          return 0;
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 1ff43d0..c974abe 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -515,8 +515,8 @@ static int QEMU_WARN_UNUSED_RESULT 
update_refcount(BlockDriverState *bs,
              s->l2_table_cache);
      }

-    start = offset & ~(s->cluster_size - 1);
-    last = (offset + length - 1) & ~(s->cluster_size - 1);
+    start = start_of_cluster(s, offset);
+    last = start_of_cluster(s, offset + length - 1);
      for(cluster_offset = start; cluster_offset <= last;
          cluster_offset += s->cluster_size)
      {
@@ -724,7 +724,7 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
      }
   redo:
      free_in_cluster = s->cluster_size -
-        (s->free_byte_offset & (s->cluster_size - 1));
+        offset_into_cluster(s, s->free_byte_offset);
      if (size <= free_in_cluster) {
          /* enough space in current cluster */
          offset = s->free_byte_offset;
@@ -732,7 +732,7 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
          free_in_cluster -= size;
          if (free_in_cluster == 0)
              s->free_byte_offset = 0;
-        if ((offset & (s->cluster_size - 1)) != 0)
+        if (offset_into_cluster(s, offset) != 0)
              qcow2_update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
                                            QCOW2_DISCARD_NEVER);
      } else {
@@ -740,7 +740,7 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
          if (offset < 0) {
              return offset;
          }
-        cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1);
+        cluster_offset = start_of_cluster(s, s->free_byte_offset);
          if ((cluster_offset + s->cluster_size) == offset) {
              /* we are lucky: contiguous data */
              offset = s->free_byte_offset;
@@ -1010,8 +1010,8 @@ static void inc_refcounts(BlockDriverState *bs,
      if (size <= 0)
          return;

-    start = offset & ~(s->cluster_size - 1);
-    last = (offset + size - 1) & ~(s->cluster_size - 1);
+    start = start_of_cluster(s, offset);
+    last = start_of_cluster(s, offset + size - 1);
      for(cluster_offset = start; cluster_offset <= last;
          cluster_offset += s->cluster_size) {
          k = cluster_offset >> s->cluster_bits;
@@ -1122,7 +1122,7 @@ static int check_refcounts_l2(BlockDriverState *bs, 
BdrvCheckResult *res,
                  offset, s->cluster_size);

              /* Correct offsets are cluster aligned */
-            if (offset & (s->cluster_size - 1)) {
+            if (offset_into_cluster(s, offset)) {
                  fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not "
                      "properly aligned; L2 entry corrupted.\n", offset);
                  res->corruptions++;
@@ -1194,7 +1194,7 @@ static int check_refcounts_l1(BlockDriverState *bs,
                  l2_offset, s->cluster_size);

              /* L2 tables are cluster aligned */
-            if (l2_offset & (s->cluster_size - 1)) {
+            if (offset_into_cluster(s, l2_offset)) {
                  fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not "
                      "cluster aligned; L1 entry corrupted\n", l2_offset);
                  res->corruptions++;
@@ -1423,7 +1423,7 @@ static int64_t realloc_refcount_block(BlockDriverState 
*bs, int reftable_index,
      }

      /* update refcount table */
-    assert(!(new_offset & (s->cluster_size - 1)));
+    assert(!offset_into_cluster(s, new_offset));
      s->refcount_table[reftable_index] = new_offset;
      ret = write_reftable_entry(bs, reftable_index);
      if (ret < 0) {
@@ -1507,7 +1507,7 @@ int qcow2_check_refcounts(BlockDriverState *bs, 
BdrvCheckResult *res,
          cluster = offset >> s->cluster_bits;

          /* Refcount blocks are cluster aligned */
-        if (offset & (s->cluster_size - 1)) {
+        if (offset_into_cluster(s, offset)) {
              fprintf(stderr, "ERROR refcount block %" PRId64 " is not "
                  "cluster aligned; refcount table entry corrupted\n", i);
              res->corruptions++;


The conversion looks good to me, and covers all the existing "s->cluster_size - 1" appearances in qcow2.

Reviewed-by: Fam Zheng <address@hidden>



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