qcow2: Convert qcow2_alloc_cluster_offset() into qcow2_alloc_host_offset()

qcow2_alloc_cluster_offset() takes an (unaligned) guest offset and
returns the (aligned) offset of the corresponding cluster in the qcow2
image.

In practice none of the callers need to know where the cluster starts
so this patch makes the function calculate and return the final host
offset directly. The function is also renamed accordingly.

See 388e581615 for a similar change to qcow2_get_cluster_offset().

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-Id: <9bfef50ec9200d752413be4fc2aeb22a28378817.1599833007.git.berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 13 insertions, 23 deletions

diff --git a/block/qcow2.c b/block/qcow2.c
index 1cb5daf..b055127 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2559,7 +2559,7 @@ static coroutine_fn int qcow2_co_pwritev_part(
     int offset_in_cluster;
     int ret;
     unsigned int cur_bytes; /* number of sectors in current iteration */
-    uint64_t cluster_offset;
+    uint64_t host_offset;
     QCowL2Meta *l2meta = NULL;
     AioTaskPool *aio = NULL;
 
@@ -2580,16 +2580,13 @@ static coroutine_fn int qcow2_co_pwritev_part(
 
         qemu_co_mutex_lock(&s->lock);
 
-        ret = qcow2_alloc_cluster_offset(bs, offset, &cur_bytes,
-                                         &cluster_offset, &l2meta);
+        ret = qcow2_alloc_host_offset(bs, offset, &cur_bytes,
+                                      &host_offset, &l2meta);
         if (ret < 0) {
             goto out_locked;
         }
 
-        assert(offset_into_cluster(s, cluster_offset) == 0);
-
-        ret = qcow2_pre_write_overlap_check(bs, 0,
-                                            cluster_offset + offset_in_cluster,
+        ret = qcow2_pre_write_overlap_check(bs, 0, host_offset,
                                             cur_bytes, true);
         if (ret < 0) {
             goto out_locked;
@@ -2601,7 +2598,7 @@ static coroutine_fn int qcow2_co_pwritev_part(
             aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
         }
         ret = qcow2_add_task(bs, aio, qcow2_co_pwritev_task_entry, 0,
-                             cluster_offset + offset_in_cluster, offset,
+                             host_offset, offset,
                              cur_bytes, qiov, qiov_offset, l2meta);
         l2meta = NULL; /* l2meta is consumed by qcow2_co_pwritev_task() */
         if (ret < 0) {
@@ -3129,13 +3126,12 @@ static int coroutine_fn preallocate_co(BlockDriverState *bs, uint64_t offset,
 
     while (bytes) {
         cur_bytes = MIN(bytes, QEMU_ALIGN_DOWN(INT_MAX, s->cluster_size));
-        ret = qcow2_alloc_cluster_offset(bs, offset, &cur_bytes,
-                                         &host_offset, &meta);
+        ret = qcow2_alloc_host_offset(bs, offset, &cur_bytes,
+                                      &host_offset, &meta);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Allocating clusters failed");
             goto out;
         }
-        host_offset += offset_into_cluster(s, offset);
 
         for (m = meta; m != NULL; m = m->next) {
             m->prealloc = true;
@@ -4043,10 +4039,9 @@ qcow2_co_copy_range_to(BlockDriverState *bs,
                        BdrvRequestFlags write_flags)
 {
     BDRVQcow2State *s = bs->opaque;
-    int offset_in_cluster;
     int ret;
     unsigned int cur_bytes; /* number of sectors in current iteration */
-    uint64_t cluster_offset;
+    uint64_t host_offset;
     QCowL2Meta *l2meta = NULL;
 
     assert(!bs->encrypted);
@@ -4057,31 +4052,26 @@ qcow2_co_copy_range_to(BlockDriverState *bs,
 
         l2meta = NULL;
 
-        offset_in_cluster = offset_into_cluster(s, dst_offset);
         cur_bytes = MIN(bytes, INT_MAX);
 
         /* TODO:
          * If src->bs == dst->bs, we could simply copy by incrementing
          * the refcnt, without copying user data.
          * Or if src->bs == dst->bs->backing->bs, we could copy by discarding. */
-        ret = qcow2_alloc_cluster_offset(bs, dst_offset, &cur_bytes,
-                                         &cluster_offset, &l2meta);
+        ret = qcow2_alloc_host_offset(bs, dst_offset, &cur_bytes,
+                                      &host_offset, &l2meta);
         if (ret < 0) {
             goto fail;
         }
 
-        assert(offset_into_cluster(s, cluster_offset) == 0);
-
-        ret = qcow2_pre_write_overlap_check(bs, 0,
-                cluster_offset + offset_in_cluster, cur_bytes, true);
+        ret = qcow2_pre_write_overlap_check(bs, 0, host_offset, cur_bytes,
+                                            true);
         if (ret < 0) {
             goto fail;
         }
 
         qemu_co_mutex_unlock(&s->lock);
-        ret = bdrv_co_copy_range_to(src, src_offset,
-                                    s->data_file,
-                                    cluster_offset + offset_in_cluster,
+        ret = bdrv_co_copy_range_to(src, src_offset, s->data_file, host_offset,
                                     cur_bytes, read_flags, write_flags);
         qemu_co_mutex_lock(&s->lock);
         if (ret < 0) {