[Qemu-devel] [PATCH v3 3/4] vmdk: support vmfsSparse files

[Fam Zheng <famz@redhat.com>]

VMware ESX hosts use a variant of the VMDK3 format, identified by the
vmfsSparse create type ad the VMFSSPARSE extent type.

It has 16 KB grain tables (L2) and a variable-size grain directory (L1).
In addition, the grain size is always 512, but that is not a problem
because it is included in the header.

The format of the extents is documented in the VMDK spec.  The format
of the descriptor file is not documented precisely, but it can be
found at http://kb.vmware.com/kb/10026353 (Recreating a missing virtual
machine disk (VMDK) descriptor file for delta disks).

With these patches, vmfsSparse files only work if opened through the
descriptor file.  Data files without descriptor files, as far as I
could understand, are not supported by ESX.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>

--
v2: Rebase to patch 01.
    Change le64_to_cpu to le32_to_cpu.
    Rename vmdk_open_vmdk3 to vmdk_open_vmfs_sparse, which represents the
    current usage of this format.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 4d282a6..3986d1d 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -481,9 +481,9 @@ static int vmdk_init_tables(BlockDriverState *bs, VmdkExtent *extent)
     return ret;
 }
 
-static int vmdk_open_vmdk3(BlockDriverState *bs,
-                           BlockDriverState *file,
-                           int flags)
+static int vmdk_open_vmfs_sparse(BlockDriverState *bs,
+                                 BlockDriverState *file,
+                                 int flags)
 {
     int ret;
     uint32_t magic;
@@ -674,7 +674,7 @@ static int vmdk_open_sparse(BlockDriverState *bs,
     magic = be32_to_cpu(magic);
     switch (magic) {
         case VMDK3_MAGIC:
-            return vmdk_open_vmdk3(bs, file, flags);
+            return vmdk_open_vmfs_sparse(bs, file, flags);
             break;
         case VMDK4_MAGIC:
             return vmdk_open_vmdk4(bs, file, flags);
@@ -718,7 +718,8 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
         }
 
         if (sectors <= 0 ||
-            (strcmp(type, "FLAT") && strcmp(type, "SPARSE")) ||
+            (strcmp(type, "FLAT") && strcmp(type, "SPARSE") &&
+             strcmp(type, "VMFSSPARSE")) ||
             (strcmp(access, "RW"))) {
             goto next_line;
         }
@@ -741,8 +742,8 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
                 return ret;
             }
             extent->flat_start_offset = flat_offset << 9;
-        } else if (!strcmp(type, "SPARSE")) {
-            /* SPARSE extent */
+        } else if (!strcmp(type, "SPARSE") || !strcmp(type, "VMFSSPARSE")) {
+            /* SPARSE extent and VMFSSPARSE extent are both "COWD" sparse file*/
             ret = vmdk_open_sparse(bs, extent_file, bs->open_flags);
             if (ret) {
                 bdrv_delete(extent_file);
@@ -789,6 +790,7 @@ static int vmdk_open_desc_file(BlockDriverState *bs, int flags,
         goto exit;
     }
     if (strcmp(ct, "monolithicFlat") &&
+        strcmp(ct, "vmfsSparse") &&
         strcmp(ct, "twoGbMaxExtentSparse") &&
         strcmp(ct, "twoGbMaxExtentFlat")) {
         fprintf(stderr,
@@ -1381,7 +1383,6 @@ static int coroutine_fn vmdk_co_write_zeroes(BlockDriverState *bs,
     return ret;
 }
 
-
 static int vmdk_create_extent(const char *filename, int64_t filesize,
                               bool flat, bool compress, bool zeroed_grain)
 {
-- 
1.8.3.1