[Qemu-devel] [PATCH 2/2] qcow2: Fix bdrv_write_compressed error handling

[Kevin Wolf <kwolf@redhat.com>]

If during allocation of compressed clusters the cluster was already allocated
uncompressed, fail and properly release the l2_table (the latter avoids a
failed assertion).

While at it, make it return some real error numbers instead of -1.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-cluster.c |    6 ++++--
 block/qcow2.c         |   11 ++++++-----
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 2f76311..f4e049f 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -568,8 +568,10 @@ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
     }
 
     cluster_offset = be64_to_cpu(l2_table[l2_index]);
-    if (cluster_offset & QCOW_OFLAG_COPIED)
-        return cluster_offset & ~QCOW_OFLAG_COPIED;
+    if (cluster_offset & QCOW_OFLAG_COPIED) {
+        qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+        return 0;
+    }
 
     if (cluster_offset)
         qcow2_free_any_clusters(bs, cluster_offset, 1);
diff --git a/block/qcow2.c b/block/qcow2.c
index 4dc980c..bf399f3 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1054,7 +1054,7 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
                        9, Z_DEFAULT_STRATEGY);
     if (ret != 0) {
         g_free(out_buf);
-        return -1;
+        return -EINVAL;
     }
 
     strm.avail_in = s->cluster_size;
@@ -1066,7 +1066,7 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
     if (ret != Z_STREAM_END && ret != Z_OK) {
         g_free(out_buf);
         deflateEnd(&strm);
-        return -1;
+        return -EINVAL;
     }
     out_len = strm.next_out - out_buf;
 
@@ -1079,12 +1079,13 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
         cluster_offset = qcow2_alloc_compressed_cluster_offset(bs,
             sector_num << 9, out_len);
         if (!cluster_offset)
-            return -1;
+            return -EIO;
         cluster_offset &= s->cluster_offset_mask;
         BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
-        if (bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len) != out_len) {
+        ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len);
+        if (ret < 0) {
             g_free(out_buf);
-            return -1;
+            return ret;
         }
     }
 
-- 
1.7.6.4