From 060bee8943c27d4d53f65570fafaa2559fcd87c3 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Fri, 7 Dec 2012 18:08:45 +0100
Subject: qcow2: Drop l2meta.cluster_offset

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..24f10012 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);
-- 
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