[Qemu-devel] [PATCH v5 0/6] vmdk: zeroed-grain GTE support

[Qemu-devel] [PATCH v5 0/6] vmdk: zeroed-grain GTE support

[Fam Zheng]

Added support for zeroed-grain GTE to VMDK according to VMDK Spec 5.0[1].

[1] Virtual Disk Format 5.0 - VMware,
    http://www.vmware.com/support/developer/vddk/vmdk_50_technote.pdf?src=vmdk

Changes since v4:
 - 6/6: Correct endianess: *m_data->l2_cache_entry = offset;


Changes since v3:
 - 5/6: Remove tmp
 - 6/6: Update L2 Cache
        Remove redundant assignment to m_data
        Simplify l2_offset assignment to m_data
        Fix m_data.offset endian.

Changes since v2:
 - all: Added 5/6 (vmdk: store fields of VmdkMetaData in cpu endian)
 - 6/6: Avoid side-effect of vmdk_L2update.
        Change function comment to gtkdoc stype.
        Fix VMDK4_FLAG_ZG.

Changes since v1:
 - all: fix From: field
 - 1/5: squash one line of ret code macro change from 2/5
 - 2/5: change VMDK4_FLAG_ZG to VMDK4_FLAG_ZERO_GRAIN
 - 3/5: move BLOCK_OPT_ZEROED_GRAIN defination from block_int.h to vmdk.c
 - 5/5: fix metadata update issue, unit test with cases 033 034

Fam Zheng (6):
  vmdk: named return code.
  vmdk: add support for “zeroed‐grain” GTE
  vmdk: Add option to create zeroed-grain image
  vmdk: change magic number to macro
  vmdk: store fields of VmdkMetaData in cpu endian
  vmdk: add bdrv_co_write_zeroes

 block/vmdk.c | 208 +++++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 145 insertions(+), 63 deletions(-)

-- 
1.8.1.4

[Qemu-devel] [PATCH v5 1/6] vmdk: named return code.

[Fam Zheng]

Internal routines in vmdk.c previously return -1 on error and 0 on
success. More return values are useful for future changes such as
zeroed-grain GTE. Change all the magic `return 0` and `return -1` to
macro names:

 * VMDK_OK      0
 * VMDK_ERROR   (-1)
 * VMDK_UNALLOC (-2)
 * VMDK_ZEROED  (-3)

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c | 60 ++++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 34 insertions(+), 26 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 7bad757..16aa29c 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -37,6 +37,14 @@
 #define VMDK4_FLAG_MARKER (1 << 17)
 #define VMDK4_GD_AT_END 0xffffffffffffffffULL
 
+
+/* VMDK internal error codes */
+#define VMDK_OK      0
+#define VMDK_ERROR   (-1)
+/* Cluster not allocated */
+#define VMDK_UNALLOC (-2)
+#define VMDK_ZEROED  (-3)
+
 typedef struct {
     uint32_t version;
     uint32_t flags;
@@ -578,22 +586,22 @@ static int vmdk_parse_description(const char *desc, const char *opt_name,
 
     opt_pos = strstr(desc, opt_name);
     if (!opt_pos) {
-        return -1;
+        return VMDK_ERROR;
     }
     /* Skip "=\"" following opt_name */
     opt_pos += strlen(opt_name) + 2;
     if (opt_pos >= end) {
-        return -1;
+        return VMDK_ERROR;
     }
     opt_end = opt_pos;
     while (opt_end < end && *opt_end != '"') {
         opt_end++;
     }
     if (opt_end == end || buf_size < opt_end - opt_pos + 1) {
-        return -1;
+        return VMDK_ERROR;
     }
     pstrcpy(buf, opt_end - opt_pos + 1, opt_pos);
-    return 0;
+    return VMDK_OK;
 }
 
 /* Open an extent file and append to bs array */
@@ -772,7 +780,7 @@ static int get_whole_cluster(BlockDriverState *bs,
         int ret;
 
         if (!vmdk_is_cid_valid(bs)) {
-            return -1;
+            return VMDK_ERROR;
         }
 
         /* floor offset to cluster */
@@ -780,17 +788,17 @@ static int get_whole_cluster(BlockDriverState *bs,
         ret = bdrv_read(bs->backing_hd, offset >> 9, whole_grain,
                 extent->cluster_sectors);
         if (ret < 0) {
-            return -1;
+            return VMDK_ERROR;
         }
 
         /* Write grain only into the active image */
         ret = bdrv_write(extent->file, cluster_offset, whole_grain,
                 extent->cluster_sectors);
         if (ret < 0) {
-            return -1;
+            return VMDK_ERROR;
         }
     }
-    return 0;
+    return VMDK_OK;
 }
 
 static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data)
@@ -803,7 +811,7 @@ static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data)
                 &(m_data->offset),
                 sizeof(m_data->offset)
             ) < 0) {
-        return -1;
+        return VMDK_ERROR;
     }
     /* update backup L2 table */
     if (extent->l1_backup_table_offset != 0) {
@@ -814,11 +822,11 @@ static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data)
                         + (m_data->l2_index * sizeof(m_data->offset)),
                     &(m_data->offset), sizeof(m_data->offset)
                 ) < 0) {
-            return -1;
+            return VMDK_ERROR;
         }
     }
 
-    return 0;
+    return VMDK_OK;
 }
 
 static int get_cluster_offset(BlockDriverState *bs,
@@ -837,17 +845,17 @@ static int get_cluster_offset(BlockDriverState *bs,
     }
     if (extent->flat) {
         *cluster_offset = extent->flat_start_offset;
-        return 0;
+        return VMDK_OK;
     }
 
     offset -= (extent->end_sector - extent->sectors) * SECTOR_SIZE;
     l1_index = (offset >> 9) / extent->l1_entry_sectors;
     if (l1_index >= extent->l1_size) {
-        return -1;
+        return VMDK_ERROR;
     }
     l2_offset = extent->l1_table[l1_index];
     if (!l2_offset) {
-        return -1;
+        return VMDK_UNALLOC;
     }
     for (i = 0; i < L2_CACHE_SIZE; i++) {
         if (l2_offset == extent->l2_cache_offsets[i]) {
@@ -877,7 +885,7 @@ static int get_cluster_offset(BlockDriverState *bs,
                 l2_table,
                 extent->l2_size * sizeof(uint32_t)
             ) != extent->l2_size * sizeof(uint32_t)) {
-        return -1;
+        return VMDK_ERROR;
     }
 
     extent->l2_cache_offsets[min_index] = l2_offset;
@@ -888,7 +896,7 @@ static int get_cluster_offset(BlockDriverState *bs,
 
     if (!*cluster_offset) {
         if (!allocate) {
-            return -1;
+            return VMDK_UNALLOC;
         }
 
         /* Avoid the L2 tables update for the images that have snapshots. */
@@ -911,7 +919,7 @@ static int get_cluster_offset(BlockDriverState *bs,
          */
         if (get_whole_cluster(
                 bs, extent, *cluster_offset, offset, allocate) == -1) {
-            return -1;
+            return VMDK_ERROR;
         }
 
         if (m_data) {
@@ -923,7 +931,7 @@ static int get_cluster_offset(BlockDriverState *bs,
         }
     }
     *cluster_offset <<= 9;
-    return 0;
+    return VMDK_OK;
 }
 
 static VmdkExtent *find_extent(BDRVVmdkState *s,
@@ -1173,7 +1181,7 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
                                 sector_num << 9, !extent->compressed,
                                 &cluster_offset);
         if (extent->compressed) {
-            if (ret == 0) {
+            if (ret == VMDK_OK) {
                 /* Refuse write to allocated cluster for streamOptimized */
                 fprintf(stderr,
                         "VMDK: can't write to allocated cluster"
@@ -1357,7 +1365,7 @@ static int filename_decompose(const char *filename, char *path, char *prefix,
 
     if (filename == NULL || !strlen(filename)) {
         fprintf(stderr, "Vmdk: no filename provided.\n");
-        return -1;
+        return VMDK_ERROR;
     }
     p = strrchr(filename, '/');
     if (p == NULL) {
@@ -1369,7 +1377,7 @@ static int filename_decompose(const char *filename, char *path, char *prefix,
     if (p != NULL) {
         p++;
         if (p - filename >= buf_len) {
-            return -1;
+            return VMDK_ERROR;
         }
         pstrcpy(path, p - filename + 1, filename);
     } else {
@@ -1382,12 +1390,12 @@ static int filename_decompose(const char *filename, char *path, char *prefix,
         postfix[0] = '\0';
     } else {
         if (q - p >= buf_len) {
-            return -1;
+            return VMDK_ERROR;
         }
         pstrcpy(prefix, q - p + 1, p);
         pstrcpy(postfix, buf_len, q);
     }
-    return 0;
+    return VMDK_OK;
 }
 
 static int relative_path(char *dest, int dest_size,
@@ -1403,11 +1411,11 @@ static int relative_path(char *dest, int dest_size,
 #endif
 
     if (!(dest && base && target)) {
-        return -1;
+        return VMDK_ERROR;
     }
     if (path_is_absolute(target)) {
         pstrcpy(dest, dest_size, target);
-        return 0;
+        return VMDK_OK;
     }
     while (base[i] == target[i]) {
         i++;
@@ -1426,7 +1434,7 @@ static int relative_path(char *dest, int dest_size,
         pstrcat(dest, dest_size, sep);
     }
     pstrcat(dest, dest_size, q);
-    return 0;
+    return VMDK_OK;
 }
 
 static int vmdk_create(const char *filename, QEMUOptionParameter *options)
-- 
1.8.1.4

[Qemu-devel] [PATCH v5 2/6] vmdk: add support for “zeroed‐grain” GTE

[Fam Zheng]

Introduced support for zeroed-grain GTE, as specified in Virtual Disk
Format 5.0[1].

    Recent VMware hosted platform products support a new “zeroed‐grain”
    grain table entry (GTE). The zeroed‐grain GTE returns all zeros on
    read.  In other words, the zeroed‐grain GTE indicates that a grain
    in the child disk is zero‐filled but does not actually occupy space
    in storage.  A sparse extent with zeroed‐grain GTE has the following
    in its header:

     * SparseExtentHeader.version = 2
     * SparseExtentHeader.flags has bit 2 set

    Other than the new flag and the possibly zeroed‐grain GTE, version 2
    sparse extents are identical to version 1.  Also, a zeroed‐grain GTE
    has value 0x1 in the GT table.

[1] Virtual Disk Format 5.0, http://www.vmware.com/support/developer/vddk/vmdk_50_technote.pdf?src=vmdk
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 16aa29c..7e07c0f 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -33,10 +33,13 @@
 #define VMDK4_MAGIC (('K' << 24) | ('D' << 16) | ('M' << 8) | 'V')
 #define VMDK4_COMPRESSION_DEFLATE 1
 #define VMDK4_FLAG_RGD (1 << 1)
+/* Zeroed-grain enable bit */
+#define VMDK4_FLAG_ZERO_GRAIN   (1 << 2)
 #define VMDK4_FLAG_COMPRESS (1 << 16)
 #define VMDK4_FLAG_MARKER (1 << 17)
 #define VMDK4_GD_AT_END 0xffffffffffffffffULL
 
+#define VMDK_GTE_ZEROED 0x1
 
 /* VMDK internal error codes */
 #define VMDK_OK      0
@@ -81,6 +84,8 @@ typedef struct VmdkExtent {
     bool flat;
     bool compressed;
     bool has_marker;
+    bool has_zero_grain;
+    int version;
     int64_t sectors;
     int64_t end_sector;
     int64_t flat_start_offset;
@@ -569,6 +574,8 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
     extent->compressed =
         le16_to_cpu(header.compressAlgorithm) == VMDK4_COMPRESSION_DEFLATE;
     extent->has_marker = le32_to_cpu(header.flags) & VMDK4_FLAG_MARKER;
+    extent->version = le32_to_cpu(header.version);
+    extent->has_zero_grain = le32_to_cpu(header.flags) & VMDK4_FLAG_ZERO_GRAIN;
     ret = vmdk_init_tables(bs, extent);
     if (ret) {
         /* free extent allocated by vmdk_add_extent */
@@ -839,6 +846,7 @@ static int get_cluster_offset(BlockDriverState *bs,
     unsigned int l1_index, l2_offset, l2_index;
     int min_index, i, j;
     uint32_t min_count, *l2_table, tmp = 0;
+    bool zeroed = false;
 
     if (m_data) {
         m_data->valid = 0;
@@ -894,9 +902,13 @@ static int get_cluster_offset(BlockDriverState *bs,
     l2_index = ((offset >> 9) / extent->cluster_sectors) % extent->l2_size;
     *cluster_offset = le32_to_cpu(l2_table[l2_index]);
 
-    if (!*cluster_offset) {
+    if (extent->has_zero_grain && *cluster_offset == VMDK_GTE_ZEROED) {
+        zeroed = true;
+    }
+
+    if (!*cluster_offset || zeroed) {
         if (!allocate) {
-            return VMDK_UNALLOC;
+            return zeroed ? VMDK_ZEROED : VMDK_UNALLOC;
         }
 
         /* Avoid the L2 tables update for the images that have snapshots. */
@@ -967,8 +979,8 @@ static int coroutine_fn vmdk_co_is_allocated(BlockDriverState *bs,
     ret = get_cluster_offset(bs, extent, NULL,
                             sector_num * 512, 0, &offset);
     qemu_co_mutex_unlock(&s->lock);
-    /* get_cluster_offset returning 0 means success */
-    ret = !ret;
+
+    ret = (ret == VMDK_OK || ret == VMDK_ZEROED);
 
     index_in_cluster = sector_num % extent->cluster_sectors;
     n = extent->cluster_sectors - index_in_cluster;
@@ -1111,9 +1123,9 @@ static int vmdk_read(BlockDriverState *bs, int64_t sector_num,
         if (n > nb_sectors) {
             n = nb_sectors;
         }
-        if (ret) {
+        if (ret != VMDK_OK) {
             /* if not allocated, try to read from parent image, if exist */
-            if (bs->backing_hd) {
+            if (bs->backing_hd && ret != VMDK_ZEROED) {
                 if (!vmdk_is_cid_valid(bs)) {
                     return -EINVAL;
                 }
-- 
1.8.1.4

[Qemu-devel] [PATCH v5 3/6] vmdk: Add option to create zeroed-grain image

[Fam Zheng]

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_ZERO_GRAIN flag bit
will be set.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 7e07c0f..cc19e20 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -48,6 +48,8 @@
 #define VMDK_UNALLOC (-2)
 #define VMDK_ZEROED  (-3)
 
+#define BLOCK_OPT_ZEROED_GRAIN "zeroed_grain"
+
 typedef struct {
     uint32_t version;
     uint32_t flags;
@@ -1262,7 +1264,7 @@ 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 +1286,10 @@ 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_ZERO_GRAIN : 0);
     header.compressAlgorithm = compress ? VMDK4_COMPRESSION_DEFLATE : 0;
     header.capacity = filesize / 512;
     header.granularity = 128;
@@ -1467,6 +1470,7 @@ 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 +1506,8 @@ 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 +1594,8 @@ 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 +1721,11 @@ 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 efficient zero writes using the zeroed-grain GTE feature"
+    },
     { NULL }
 };
 
-- 
1.8.1.4

[Qemu-devel] [PATCH v5 4/6] vmdk: change magic number to macro

[Fam Zheng]

Two hard coded flag bits are changed to macros.
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index cc19e20..0463d3b 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -32,6 +32,7 @@
 #define VMDK3_MAGIC (('C' << 24) | ('O' << 16) | ('W' << 8) | 'D')
 #define VMDK4_MAGIC (('K' << 24) | ('D' << 16) | ('M' << 8) | 'V')
 #define VMDK4_COMPRESSION_DEFLATE 1
+#define VMDK4_FLAG_NL_DETECT (1 << 0)
 #define VMDK4_FLAG_RGD (1 << 1)
 /* Zeroed-grain enable bit */
 #define VMDK4_FLAG_ZERO_GRAIN   (1 << 2)
@@ -1287,7 +1288,7 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
     magic = cpu_to_be32(VMDK4_MAGIC);
     memset(&header, 0, sizeof(header));
     header.version = zeroed_grain ? 2 : 1;
-    header.flags = 3
+    header.flags = VMDK4_FLAG_RGD | VMDK4_FLAG_NL_DETECT
                    | (compress ? VMDK4_FLAG_COMPRESS | VMDK4_FLAG_MARKER : 0)
                    | (zeroed_grain ? VMDK4_FLAG_ZERO_GRAIN : 0);
     header.compressAlgorithm = compress ? VMDK4_COMPRESSION_DEFLATE : 0;
-- 
1.8.1.4

[Qemu-devel] [PATCH v5 5/6] vmdk: store fields of VmdkMetaData in cpu endian

[Fam Zheng]

Previously VmdkMetaData.offset is stored little endian while other
fields are cpu endian. This changes offset to cpu endian and convert
before writing to image.
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 0463d3b..d98f304 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -813,14 +813,15 @@ static int get_whole_cluster(BlockDriverState *bs,
 
 static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data)
 {
+    uint32_t offset;
+    QEMU_BUILD_BUG_ON(sizeof(offset) != sizeof(m_data->offset));
+    offset = cpu_to_le32(m_data->offset);
     /* update L2 table */
     if (bdrv_pwrite_sync(
                 extent->file,
                 ((int64_t)m_data->l2_offset * 512)
                     + (m_data->l2_index * sizeof(m_data->offset)),
-                &(m_data->offset),
-                sizeof(m_data->offset)
-            ) < 0) {
+                &offset, sizeof(offset)) < 0) {
         return VMDK_ERROR;
     }
     /* update backup L2 table */
@@ -830,8 +831,7 @@ static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data)
                     extent->file,
                     ((int64_t)m_data->l2_offset * 512)
                         + (m_data->l2_index * sizeof(m_data->offset)),
-                    &(m_data->offset), sizeof(m_data->offset)
-                ) < 0) {
+                    &offset, sizeof(offset)) < 0) {
             return VMDK_ERROR;
         }
     }
@@ -848,7 +848,7 @@ static int get_cluster_offset(BlockDriverState *bs,
 {
     unsigned int l1_index, l2_offset, l2_index;
     int min_index, i, j;
-    uint32_t min_count, *l2_table, tmp = 0;
+    uint32_t min_count, *l2_table;
     bool zeroed = false;
 
     if (m_data) {
@@ -924,8 +924,7 @@ static int get_cluster_offset(BlockDriverState *bs,
         }
 
         *cluster_offset >>= 9;
-        tmp = cpu_to_le32(*cluster_offset);
-        l2_table[l2_index] = tmp;
+        l2_table[l2_index] = cpu_to_le32(*cluster_offset);
 
         /* First of all we write grain itself, to avoid race condition
          * that may to corrupt the image.
@@ -938,7 +937,7 @@ static int get_cluster_offset(BlockDriverState *bs,
         }
 
         if (m_data) {
-            m_data->offset = tmp;
+            m_data->offset = *cluster_offset;
             m_data->l1_index = l1_index;
             m_data->l2_index = l2_index;
             m_data->l2_offset = l2_offset;
-- 
1.8.1.4

[Qemu-devel] [PATCH v5 6/6] vmdk: add bdrv_co_write_zeroes

[Fam Zheng]

Use special offset to write zeroes efficiently, when zeroed-grain GTE is
available. If zero-write an allocated cluster, cluster is leaked because
its offset pointer is overwritten by "0x1".

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/vmdk.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 68 insertions(+), 18 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index d98f304..608daaf 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -124,6 +124,7 @@ typedef struct VmdkMetaData {
     unsigned int l2_index;
     unsigned int l2_offset;
     int valid;
+    uint32_t *l2_cache_entry;
 } VmdkMetaData;
 
 typedef struct VmdkGrainMarker {
@@ -835,6 +836,9 @@ static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data)
             return VMDK_ERROR;
         }
     }
+    if (m_data->l2_cache_entry) {
+        *m_data->l2_cache_entry = offset;
+    }
 
     return VMDK_OK;
 }
@@ -905,6 +909,14 @@ static int get_cluster_offset(BlockDriverState *bs,
     l2_index = ((offset >> 9) / extent->cluster_sectors) % extent->l2_size;
     *cluster_offset = le32_to_cpu(l2_table[l2_index]);
 
+    if (m_data) {
+        m_data->valid = 1;
+        m_data->l1_index = l1_index;
+        m_data->l2_index = l2_index;
+        m_data->offset = *cluster_offset;
+        m_data->l2_offset = l2_offset;
+        m_data->l2_cache_entry = &l2_table[l2_index];
+    }
     if (extent->has_zero_grain && *cluster_offset == VMDK_GTE_ZEROED) {
         zeroed = true;
     }
@@ -938,10 +950,6 @@ static int get_cluster_offset(BlockDriverState *bs,
 
         if (m_data) {
             m_data->offset = *cluster_offset;
-            m_data->l1_index = l1_index;
-            m_data->l2_index = l2_index;
-            m_data->l2_offset = l2_offset;
-            m_data->valid = 1;
         }
     }
     *cluster_offset <<= 9;
@@ -1164,8 +1172,17 @@ static coroutine_fn int vmdk_co_read(BlockDriverState *bs, int64_t sector_num,
     return ret;
 }
 
+/**
+ * vmdk_write:
+ * @zeroed:       buf is ignored (data is zero), use zeroed_grain GTE feature
+ * if possible, otherwise return -ENOTSUP.
+ * @zero_dry_run: used for zeroed == true only, don't update L2 table, just
+ *
+ * Returns: error code with 0 for success.
+ */
 static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
-                     const uint8_t *buf, int nb_sectors)
+                      const uint8_t *buf, int nb_sectors,
+                      bool zeroed, bool zero_dry_run)
 {
     BDRVVmdkState *s = bs->opaque;
     VmdkExtent *extent = NULL;
@@ -1211,7 +1228,7 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
                                         &cluster_offset);
             }
         }
-        if (ret) {
+        if (ret == VMDK_ERROR) {
             return -EINVAL;
         }
         extent_begin_sector = extent->end_sector - extent->sectors;
@@ -1221,17 +1238,34 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
         if (n > nb_sectors) {
             n = nb_sectors;
         }
-
-        ret = vmdk_write_extent(extent,
-                        cluster_offset, index_in_cluster * 512,
-                        buf, n, sector_num);
-        if (ret) {
-            return ret;
-        }
-        if (m_data.valid) {
-            /* update L2 tables */
-            if (vmdk_L2update(extent, &m_data) == -1) {
-                return -EIO;
+        if (zeroed) {
+            /* Do zeroed write, buf is ignored */
+            if (extent->has_zero_grain &&
+                    index_in_cluster == 0 &&
+                    n >= extent->cluster_sectors) {
+                n = extent->cluster_sectors;
+                if (!zero_dry_run) {
+                    m_data.offset = VMDK_GTE_ZEROED;
+                    /* update L2 tables */
+                    if (vmdk_L2update(extent, &m_data) != VMDK_OK) {
+                        return -EIO;
+                    }
+                }
+            } else {
+                return -ENOTSUP;
+            }
+        } else {
+            ret = vmdk_write_extent(extent,
+                            cluster_offset, index_in_cluster * 512,
+                            buf, n, sector_num);
+            if (ret) {
+                return ret;
+            }
+            if (m_data.valid) {
+                /* update L2 tables */
+                if (vmdk_L2update(extent, &m_data) != VMDK_OK) {
+                    return -EIO;
+                }
             }
         }
         nb_sectors -= n;
@@ -1257,7 +1291,22 @@ static coroutine_fn int vmdk_co_write(BlockDriverState *bs, int64_t sector_num,
     int ret;
     BDRVVmdkState *s = bs->opaque;
     qemu_co_mutex_lock(&s->lock);
-    ret = vmdk_write(bs, sector_num, buf, nb_sectors);
+    ret = vmdk_write(bs, sector_num, buf, nb_sectors, false, false);
+    qemu_co_mutex_unlock(&s->lock);
+    return ret;
+}
+
+static int coroutine_fn vmdk_co_write_zeroes(BlockDriverState *bs,
+                                             int64_t sector_num,
+                                             int nb_sectors)
+{
+    int ret;
+    BDRVVmdkState *s = bs->opaque;
+    qemu_co_mutex_lock(&s->lock);
+    ret = vmdk_write(bs, sector_num, NULL, nb_sectors, true, true);
+    if (!ret) {
+        ret = vmdk_write(bs, sector_num, NULL, nb_sectors, true, false);
+    }
     qemu_co_mutex_unlock(&s->lock);
     return ret;
 }
@@ -1737,6 +1786,7 @@ static BlockDriver bdrv_vmdk = {
     .bdrv_reopen_prepare = vmdk_reopen_prepare,
     .bdrv_read      = vmdk_co_read,
     .bdrv_write     = vmdk_co_write,
+    .bdrv_co_write_zeroes = vmdk_co_write_zeroes,
     .bdrv_close     = vmdk_close,
     .bdrv_create    = vmdk_create,
     .bdrv_co_flush_to_disk  = vmdk_co_flush,
-- 
1.8.1.4

Re: [Qemu-devel] [PATCH v5 0/6] vmdk: zeroed-grain GTE support

[Stefan Hajnoczi]

On Thu, May 02, 2013 at 10:25:21AM +0800, Fam Zheng wrote:
> Added support for zeroed-grain GTE to VMDK according to VMDK Spec 5.0[1].
> 
> [1] Virtual Disk Format 5.0 - VMware,
>     http://www.vmware.com/support/developer/vddk/vmdk_50_technote.pdf?src=vmdk
> 
> Changes since v4:
>  - 6/6: Correct endianess: *m_data->l2_cache_entry = offset;
> 
> 
> Changes since v3:
>  - 5/6: Remove tmp
>  - 6/6: Update L2 Cache
>         Remove redundant assignment to m_data
>         Simplify l2_offset assignment to m_data
>         Fix m_data.offset endian.
> 
> Changes since v2:
>  - all: Added 5/6 (vmdk: store fields of VmdkMetaData in cpu endian)
>  - 6/6: Avoid side-effect of vmdk_L2update.
>         Change function comment to gtkdoc stype.
>         Fix VMDK4_FLAG_ZG.
> 
> Changes since v1:
>  - all: fix From: field
>  - 1/5: squash one line of ret code macro change from 2/5
>  - 2/5: change VMDK4_FLAG_ZG to VMDK4_FLAG_ZERO_GRAIN
>  - 3/5: move BLOCK_OPT_ZEROED_GRAIN defination from block_int.h to vmdk.c
>  - 5/5: fix metadata update issue, unit test with cases 033 034
> 
> Fam Zheng (6):
>   vmdk: named return code.
>   vmdk: add support for “zeroed‐grain” GTE
>   vmdk: Add option to create zeroed-grain image
>   vmdk: change magic number to macro
>   vmdk: store fields of VmdkMetaData in cpu endian
>   vmdk: add bdrv_co_write_zeroes
> 
>  block/vmdk.c | 208 +++++++++++++++++++++++++++++++++++++++++------------------
>  1 file changed, 145 insertions(+), 63 deletions(-)

Patches look fine now.  The new option breaks qemu-iotests though:

$ cd tests/qemu-iotests
$ QEMU_PROG=$HOME/qemu/x86_64-softmmu/qemu-system-x86_64 \
  PATH=$HOME/qemu:$PATH \
  ./check -vmdk
[...]
001 1s ... - output mismatch (see 001.out.bad)
--- 001.out	2013-04-04 13:26:21.394050764 +0200
+++ 001.out.bad	2013-05-02 16:52:55.685803943 +0200
@@ -1,5 +1,5 @@
 QA output created by 001
 -Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 
 +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 zeroed_grain=off

You'll need to filter out zeroed_grain from qemu-img output.  We already
do this for other options.

Please send a patch to fix qemu-iotests so that I can apply this series.

Thanks,
Stefan

Re: [Qemu-devel] [PATCH v5 0/6] vmdk: zeroed-grain GTE support

[Stefan Hajnoczi]

On Thu, May 02, 2013 at 10:25:21AM +0800, Fam Zheng wrote:
> Added support for zeroed-grain GTE to VMDK according to VMDK Spec 5.0[1].
> 
> [1] Virtual Disk Format 5.0 - VMware,
>     http://www.vmware.com/support/developer/vddk/vmdk_50_technote.pdf?src=vmdk
> 
> Changes since v4:
>  - 6/6: Correct endianess: *m_data->l2_cache_entry = offset;
> 
> 
> Changes since v3:
>  - 5/6: Remove tmp
>  - 6/6: Update L2 Cache
>         Remove redundant assignment to m_data
>         Simplify l2_offset assignment to m_data
>         Fix m_data.offset endian.
> 
> Changes since v2:
>  - all: Added 5/6 (vmdk: store fields of VmdkMetaData in cpu endian)
>  - 6/6: Avoid side-effect of vmdk_L2update.
>         Change function comment to gtkdoc stype.
>         Fix VMDK4_FLAG_ZG.
> 
> Changes since v1:
>  - all: fix From: field
>  - 1/5: squash one line of ret code macro change from 2/5
>  - 2/5: change VMDK4_FLAG_ZG to VMDK4_FLAG_ZERO_GRAIN
>  - 3/5: move BLOCK_OPT_ZEROED_GRAIN defination from block_int.h to vmdk.c
>  - 5/5: fix metadata update issue, unit test with cases 033 034
> 
> Fam Zheng (6):
>   vmdk: named return code.
>   vmdk: add support for “zeroed‐grain” GTE
>   vmdk: Add option to create zeroed-grain image
>   vmdk: change magic number to macro
>   vmdk: store fields of VmdkMetaData in cpu endian
>   vmdk: add bdrv_co_write_zeroes
> 
>  block/vmdk.c | 208 +++++++++++++++++++++++++++++++++++++++++------------------
>  1 file changed, 145 insertions(+), 63 deletions(-)
> 
> -- 
> 1.8.1.4
> 
> 

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan