[Qemu-devel] [PATCH 01/10] qcow2: Write feature table only for v3 images

[Kevin Wolf <kwolf@redhat.com>]

Version 2 images don't have feature bits, so writing a feature table to
those images is kind of pointless.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.c              | 48 ++++++++++++++++++++++++----------------------
 tests/qemu-iotests/031.out | 12 +-----------
 tests/qemu-iotests/061.out | 15 ---------------
 3 files changed, 26 insertions(+), 49 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 1789af4..5f22e18 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1895,31 +1895,33 @@ int qcow2_update_header(BlockDriverState *bs)
     }
 
     /* Feature table */
-    Qcow2Feature features[] = {
-        {
-            .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
-            .bit  = QCOW2_INCOMPAT_DIRTY_BITNR,
-            .name = "dirty bit",
-        },
-        {
-            .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
-            .bit  = QCOW2_INCOMPAT_CORRUPT_BITNR,
-            .name = "corrupt bit",
-        },
-        {
-            .type = QCOW2_FEAT_TYPE_COMPATIBLE,
-            .bit  = QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
-            .name = "lazy refcounts",
-        },
-    };
+    if (s->qcow_version >= 3) {
+        Qcow2Feature features[] = {
+            {
+                .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
+                .bit  = QCOW2_INCOMPAT_DIRTY_BITNR,
+                .name = "dirty bit",
+            },
+            {
+                .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
+                .bit  = QCOW2_INCOMPAT_CORRUPT_BITNR,
+                .name = "corrupt bit",
+            },
+            {
+                .type = QCOW2_FEAT_TYPE_COMPATIBLE,
+                .bit  = QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
+                .name = "lazy refcounts",
+            },
+        };
 
-    ret = header_ext_add(buf, QCOW2_EXT_MAGIC_FEATURE_TABLE,
-                         features, sizeof(features), buflen);
-    if (ret < 0) {
-        goto fail;
+        ret = header_ext_add(buf, QCOW2_EXT_MAGIC_FEATURE_TABLE,
+                             features, sizeof(features), buflen);
+        if (ret < 0) {
+            goto fail;
+        }
+        buf += ret;
+        buflen -= ret;
     }
-    buf += ret;
-    buflen -= ret;
 
     /* Keep unknown header extensions */
     QLIST_FOREACH(uext, &s->unknown_header_ext, next) {
diff --git a/tests/qemu-iotests/031.out b/tests/qemu-iotests/031.out
index fce3ce0..f065404 100644
--- a/tests/qemu-iotests/031.out
+++ b/tests/qemu-iotests/031.out
@@ -53,11 +53,6 @@ refcount_order            4
 header_length             72
 
 Header extension:
-magic                     0x6803f857
-length                    144
-data                      <binary>
-
-Header extension:
 magic                     0x12345678
 length                    31
 data                      'This is a test header extension'
@@ -68,7 +63,7 @@ No errors were found on the image.
 
 magic                     0x514649fb
 version                   2
-backing_file_offset       0x128
+backing_file_offset       0x90
 backing_file_size         0x17
 cluster_bits              16
 size                      67108864
@@ -91,11 +86,6 @@ length                    11
 data                      'host_device'
 
 Header extension:
-magic                     0x6803f857
-length                    144
-data                      <binary>
-
-Header extension:
 magic                     0x12345678
 length                    31
 data                      'This is a test header extension'
diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out
index 57aae28..d604682 100644
--- a/tests/qemu-iotests/061.out
+++ b/tests/qemu-iotests/061.out
@@ -43,11 +43,6 @@ autoclear_features        0x0
 refcount_order            4
 header_length             72
 
-Header extension:
-magic                     0x6803f857
-length                    144
-data                      <binary>
-
 read 131072/131072 bytes at offset 0
 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 No errors were found on the image.
@@ -105,11 +100,6 @@ autoclear_features        0x0
 refcount_order            4
 header_length             72
 
-Header extension:
-magic                     0x6803f857
-length                    144
-data                      <binary>
-
 read 131072/131072 bytes at offset 0
 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 No errors were found on the image.
@@ -155,11 +145,6 @@ autoclear_features        0x0
 refcount_order            4
 header_length             72
 
-Header extension:
-magic                     0x6803f857
-length                    144
-data                      <binary>
-
 No errors were found on the image.
 
 === Testing version upgrade and resize ===
-- 
1.8.3.1