[Qemu-devel] [PATCH 4/8] qcow2: Drop l2meta.cluster_offset

[Kevin Wolf <kwolf@redhat.com>]

There's no real reason to have an l2meta for normal requests that don't
allocate anything. Before we can get rid of it, we must return the host
cluster offset in a different way.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-cluster.c |   10 ++++++----
 block/qcow2.c         |   14 +++++++-------
 block/qcow2.h         |    5 +----
 3 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 94b7f13..c4752ee 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -856,7 +856,7 @@ static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
  * Return 0 on success and -errno in error cases
  */
 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
-    int n_start, int n_end, int *num, QCowL2Meta *m)
+    int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta *m)
 {
     BDRVQcowState *s = bs->opaque;
     int l2_index, ret, sectors;
@@ -929,7 +929,6 @@ again:
 
     /* If there is something left to allocate, do that now */
     *m = (QCowL2Meta) {
-        .cluster_offset     = cluster_offset,
         .nb_clusters        = 0,
     };
     qemu_co_queue_init(&m->dependent_requests);
@@ -977,9 +976,11 @@ again:
             int alloc_n_start = keep_clusters == 0 ? n_start : 0;
             int nb_sectors = MIN(requested_sectors, avail_sectors);
 
+            if (keep_clusters == 0) {
+                cluster_offset = alloc_cluster_offset;
+            }
+
             *m = (QCowL2Meta) {
-                .cluster_offset = keep_clusters == 0 ?
-                                  alloc_cluster_offset : cluster_offset,
                 .alloc_offset   = alloc_cluster_offset,
                 .offset         = alloc_offset & ~(s->cluster_size - 1),
                 .nb_clusters    = nb_clusters,
@@ -1007,6 +1008,7 @@ again:
 
     assert(sectors > n_start);
     *num = sectors - n_start;
+    *host_offset = cluster_offset;
 
     return 0;
 
diff --git a/block/qcow2.c b/block/qcow2.c
index 71f870d..66ca12f 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -799,7 +799,7 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
         }
 
         ret = qcow2_alloc_cluster_offset(bs, sector_num << 9,
-            index_in_cluster, n_end, &cur_nr_sectors, l2meta);
+            index_in_cluster, n_end, &cur_nr_sectors, &cluster_offset, l2meta);
         if (ret < 0) {
             goto fail;
         }
@@ -809,7 +809,6 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
             qcow2_mark_dirty(bs);
         }
 
-        cluster_offset = l2meta->cluster_offset;
         assert((cluster_offset & 511) == 0);
 
         qemu_iovec_reset(&hd_qiov);
@@ -1132,6 +1131,7 @@ static int preallocate(BlockDriverState *bs)
 {
     uint64_t nb_sectors;
     uint64_t offset;
+    uint64_t host_offset = 0;
     int num;
     int ret;
     QCowL2Meta meta;
@@ -1139,18 +1139,18 @@ static int preallocate(BlockDriverState *bs)
     nb_sectors = bdrv_getlength(bs) >> 9;
     offset = 0;
     qemu_co_queue_init(&meta.dependent_requests);
-    meta.cluster_offset = 0;
 
     while (nb_sectors) {
         num = MIN(nb_sectors, INT_MAX >> 9);
-        ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num, &meta);
+        ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num,
+                                         &host_offset, &meta);
         if (ret < 0) {
             return ret;
         }
 
         ret = qcow2_alloc_cluster_link_l2(bs, &meta);
         if (ret < 0) {
-            qcow2_free_any_clusters(bs, meta.cluster_offset, meta.nb_clusters);
+            qcow2_free_any_clusters(bs, meta.alloc_offset, meta.nb_clusters);
             return ret;
         }
 
@@ -1169,10 +1169,10 @@ static int preallocate(BlockDriverState *bs)
      * all of the allocated clusters (otherwise we get failing reads after
      * EOF). Extend the image to the last allocated sector.
      */
-    if (meta.cluster_offset != 0) {
+    if (host_offset != 0) {
         uint8_t buf[512];
         memset(buf, 0, 512);
-        ret = bdrv_write(bs->file, (meta.cluster_offset >> 9) + num - 1, buf, 1);
+        ret = bdrv_write(bs->file, (host_offset >> 9) + num - 1, buf, 1);
         if (ret < 0) {
             return ret;
         }
diff --git a/block/qcow2.h b/block/qcow2.h
index 1106b33..24f1001 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -213,9 +213,6 @@ typedef struct QCowL2Meta
     /** Guest offset of the first newly allocated cluster */
     uint64_t offset;
 
-    /** Host offset of the first cluster of the request */
-    uint64_t cluster_offset;
-
     /** Host offset of the first newly allocated cluster */
     uint64_t alloc_offset;
 
@@ -336,7 +333,7 @@ void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
     int *num, uint64_t *cluster_offset);
 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
-    int n_start, int n_end, int *num, QCowL2Meta *m);
+    int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta *m);
 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
                                          uint64_t offset,
                                          int compressed_size);
-- 
1.7.6.5