diff mbox

[3/5] vmdk: Add option to create zeroed-grain image

Message ID 1366343325-5252-4-git-send-email-famz@redhat.com
State New
Headers show

Commit Message

Fam Zheng April 19, 2013, 3:48 a.m. UTC 
From: Feiran Zheng <feiran.zheng@emc.com>

Add image create option "zeroed-grain" to enable zeroed-grain GTE
feature of vmdk sparse extents. When this option is on, header version
of newly created extent will be 2 and VMDK4_FLAG_ZG flag bit will be
set.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c              | 20 +++++++++++++++-----
 include/block/block_int.h |  1 +
 2 files changed, 16 insertions(+), 5 deletions(-)

Comments

Stefan Hajnoczi April 19, 2013, 9:05 a.m. UTC | #1 
On Fri, Apr 19, 2013 at 11:48:43AM +0800, Fam Zheng wrote:
> @@ -1714,6 +1719,11 @@ static QEMUOptionParameter vmdk_create_options[] = {
>              "VMDK flat extent format, can be one of "
>              "{monolithicSparse (default) | monolithicFlat | twoGbMaxExtentSparse | twoGbMaxExtentFlat | streamOptimized} "
>      },
> +    {
> +        .name = BLOCK_OPT_ZEROED_GRAIN,

This option should be #defined in this patch.

> +        .type = OPT_FLAG,
> +        .help = "Enable zeroed-grain featur (implies header.version = 2)"

This message doesn't help the user.  Maybe something like this?

"Enable efficient zero writes using the zeroed-grain GTE feature"

I think header.version = 2 isn't relevant to users.  People who care
will have read the VMDK specification already.
diff mbox

Patch

diff --git a/block/vmdk.c b/block/vmdk.c
index 5e60940..827b35b 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1262,7 +1262,7 @@  static coroutine_fn int vmdk_co_write(BlockDriverState *bs, int64_t sector_num,
 
 
 static int vmdk_create_extent(const char *filename, int64_t filesize,
-                              bool flat, bool compress)
+                              bool flat, bool compress, bool zeroed_grain)
 {
     int ret, i;
     int fd = 0;
@@ -1284,9 +1284,10 @@  static int vmdk_create_extent(const char *filename, int64_t filesize,
     }
     magic = cpu_to_be32(VMDK4_MAGIC);
     memset(&header, 0, sizeof(header));
-    header.version = 1;
-    header.flags =
-        3 | (compress ? VMDK4_FLAG_COMPRESS | VMDK4_FLAG_MARKER : 0);
+    header.version = zeroed_grain ? 2 : 1;
+    header.flags = 3
+                   | (compress ? VMDK4_FLAG_COMPRESS | VMDK4_FLAG_MARKER : 0)
+                   | (zeroed_grain ? VMDK4_FLAG_ZG : 0);
     header.compressAlgorithm = compress ? VMDK4_COMPRESSION_DEFLATE : 0;
     header.capacity = filesize / 512;
     header.granularity = 128;
@@ -1467,6 +1468,7 @@  static int vmdk_create(const char *filename, QEMUOptionParameter *options)
     char parent_desc_line[BUF_SIZE] = "";
     uint32_t parent_cid = 0xffffffff;
     uint32_t number_heads = 16;
+    bool zeroed_grain = false;
     const char desc_template[] =
         "# Disk DescriptorFile\n"
         "version=1\n"
@@ -1502,6 +1504,8 @@  static int vmdk_create(const char *filename, QEMUOptionParameter *options)
             flags |= options->value.n ? BLOCK_FLAG_COMPAT6 : 0;
         } else if (!strcmp(options->name, BLOCK_OPT_SUBFMT)) {
             fmt = options->value.s;
+        } else if (!strcmp(options->name, BLOCK_OPT_ZEROED_GRAIN)) {
+            zeroed_grain |= options->value.n;
         }
         options++;
     }
@@ -1588,7 +1592,8 @@  static int vmdk_create(const char *filename, QEMUOptionParameter *options)
         snprintf(ext_filename, sizeof(ext_filename), "%s%s",
                 path, desc_filename);
 
-        if (vmdk_create_extent(ext_filename, size, flat, compress)) {
+        if (vmdk_create_extent(ext_filename, size,
+                               flat, compress, zeroed_grain)) {
             return -EINVAL;
         }
         filesize -= size;
@@ -1714,6 +1719,11 @@  static QEMUOptionParameter vmdk_create_options[] = {
             "VMDK flat extent format, can be one of "
             "{monolithicSparse (default) | monolithicFlat | twoGbMaxExtentSparse | twoGbMaxExtentFlat | streamOptimized} "
     },
+    {
+        .name = BLOCK_OPT_ZEROED_GRAIN,
+        .type = OPT_FLAG,
+        .help = "Enable zeroed-grain featur (implies header.version = 2)"
+    },
     { NULL }
 };
 
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 9aa98b5..2c0f94c 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -57,6 +57,7 @@ 
 #define BLOCK_OPT_COMPAT_LEVEL      "compat"
 #define BLOCK_OPT_LAZY_REFCOUNTS    "lazy_refcounts"
 #define BLOCK_OPT_ADAPTER_TYPE      "adapter_type"
+#define BLOCK_OPT_ZEROED_GRAIN      "zeroed_grain"
 
 typedef struct BdrvTrackedRequest BdrvTrackedRequest;