[Qemu-devel] [PATCH 1/2] vmdk: support vmfsSparse files

[Paolo Bonzini]

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 <address@hidden>
---
 block/vmdk.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 46 insertions(+), 5 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index b16d509..eaf484a 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -505,6 +505,34 @@ static int vmdk_open_vmdk3(BlockDriverState *bs,
     return ret;
 }
 
+static int vmdk_open_vmfs_sparse(BlockDriverState *bs,
+                                 BlockDriverState *file,
+                                 int flags)
+{
+    int ret;
+    uint32_t magic;
+    VMDK3Header header;
+    VmdkExtent *extent;
+
+    ret = bdrv_pread(file, sizeof(magic), &header, sizeof(header));
+    if (ret < 0) {
+        return ret;
+    }
+    extent = vmdk_add_extent(bs, file, false,
+                          le64_to_cpu(header.disk_sectors),
+                          le64_to_cpu(header.l1dir_offset) << 9,
+                          0,
+                          le64_to_cpu(header.l1dir_size) * 4,
+                          4096,
+                          le64_to_cpu(header.granularity)); /* always 512 */
+    ret = vmdk_init_tables(bs, extent);
+    if (ret) {
+        /* free extent allocated by vmdk_add_extent */
+        vmdk_free_last_extent(bs);
+    }
+    return ret;
+}
+
 static int vmdk_open_desc_file(BlockDriverState *bs, int flags,
                                uint64_t desc_offset);
 
@@ -663,7 +691,7 @@ static int vmdk_parse_description(const char *desc, const 
char *opt_name,
 /* Open an extent file and append to bs array */
 static int vmdk_open_sparse(BlockDriverState *bs,
                             BlockDriverState *file,
-                            int flags)
+                            int flags, bool vmfs_sparse)
 {
     uint32_t magic;
 
@@ -674,7 +702,11 @@ static int vmdk_open_sparse(BlockDriverState *bs,
     magic = be32_to_cpu(magic);
     switch (magic) {
         case VMDK3_MAGIC:
-            return vmdk_open_vmdk3(bs, file, flags);
+            if (vmfs_sparse) {
+                return vmdk_open_vmfs_sparse(bs, file, flags);
+            } else {
+                return vmdk_open_vmdk3(bs, file, flags);
+            }
             break;
         case VMDK4_MAGIC:
             return vmdk_open_vmdk4(bs, file, flags);
@@ -718,7 +750,8 @@ 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;
         }
@@ -743,7 +776,14 @@ static int vmdk_parse_extents(const char *desc, 
BlockDriverState *bs,
             extent->flat_start_offset = flat_offset << 9;
         } else if (!strcmp(type, "SPARSE")) {
             /* SPARSE extent */
-            ret = vmdk_open_sparse(bs, extent_file, bs->open_flags);
+            ret = vmdk_open_sparse(bs, extent_file, bs->open_flags, false);
+            if (ret) {
+                bdrv_delete(extent_file);
+                return ret;
+            }
+        } else if (!strcmp(type, "VMFSSPARSE")) {
+            /* VMFSSPARSE extent */
+            ret = vmdk_open_sparse(bs, extent_file, bs->open_flags, true);
             if (ret) {
                 bdrv_delete(extent_file);
                 return ret;
@@ -789,6 +829,7 @@ 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,
@@ -808,7 +849,7 @@ static int vmdk_open(BlockDriverState *bs, QDict *options, 
int flags)
     int ret;
     BDRVVmdkState *s = bs->opaque;
 
-    if (vmdk_open_sparse(bs, bs->file, flags) == 0) {
+    if (vmdk_open_sparse(bs, bs->file, flags, false) == 0) {
         s->desc_offset = 0x200;
     } else {
         ret = vmdk_open_desc_file(bs, flags, 0);
-- 
1.8.3.1