[Qemu-devel] [PATCH 0/5] vmdk: zeroed-grain GTE support

[Qemu-devel] [PATCH 0/5] 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


Feiran Zheng (5):
  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: add bdrv_co_write_zeroes

 block/vmdk.c              | 166 ++++++++++++++++++++++++++++++++--------------
 include/block/block_int.h |   1 +
 2 files changed, 118 insertions(+), 49 deletions(-)

-- 
1.8.1.4

[Qemu-devel] [PATCH 1/5] vmdk: named return code.

[Fam Zheng]

From: Feiran Zheng <feiran.zheng@emc.com>

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 | 58 +++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 33 insertions(+), 25 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 7bad757..450a721 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,
@@ -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 2/5] vmdk: add support for “zeroed‐grain” GTE

[Fam Zheng]

From: Feiran Zheng <feiran.zheng@emc.com>

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 | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 450a721..5e60940 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_ZG   (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_ZG;
     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;
                 }
@@ -1181,7 +1193,7 @@ 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"
-- 
1.8.1.4

Re: [Qemu-devel] [PATCH 2/5] vmdk: add support for “zeroed‐grain” GTE

[Stefan Hajnoczi]

On Fri, Apr 19, 2013 at 11:48:42AM +0800, Fam Zheng wrote:
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 450a721..5e60940 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_ZG   (1 << 2)

Please use a clear name like VMDK4_FLAG_ZERO_GRAIN.

> @@ -81,6 +84,8 @@ typedef struct VmdkExtent {
>      bool flat;
>      bool compressed;
>      bool has_marker;
> +    bool has_zero_grain;
> +    int version;

uint32_t according to the spec.  Please use fixed-size integer types
instead of int, long, etc which can change depending on the host
architecture.

> @@ -1181,7 +1193,7 @@ 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) {

Should this be squashed into the previous patch?

Re: [Qemu-devel] [PATCH 2/5] vmdk: add support for “zeroed‐grain” GTE

[Fam Zheng]

On Fri, 04/19 10:59, Stefan Hajnoczi wrote:
> On Fri, Apr 19, 2013 at 11:48:42AM +0800, Fam Zheng wrote:
> > diff --git a/block/vmdk.c b/block/vmdk.c
> > index 450a721..5e60940 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_ZG   (1 << 2)
> 
> Please use a clear name like VMDK4_FLAG_ZERO_GRAIN.
> 
> > @@ -81,6 +84,8 @@ typedef struct VmdkExtent {
> >      bool flat;
> >      bool compressed;
> >      bool has_marker;
> > +    bool has_zero_grain;
> > +    int version;
> 
> uint32_t according to the spec.  Please use fixed-size integer types
> instead of int, long, etc which can change depending on the host
> architecture.

This is an internal structure holding information for extent, used the
same way as BDRVVmdkState, there is no direct correspondence to file
header fields, so I think it should be OK, as `int qcow_version' is also
found in block/qcow2.h.

> 
> > @@ -1181,7 +1193,7 @@ 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) {
> 
> Should this be squashed into the previous patch?

Yes.

-- 
Fam

Re: [Qemu-devel] [PATCH 2/5] vmdk: add support for “zeroed‐grain” GTE

[Stefan Hajnoczi]

On Fri, Apr 19, 2013 at 11:10 AM, Fam Zheng <famz@redhat.com> wrote:
> On Fri, 04/19 10:59, Stefan Hajnoczi wrote:
>> On Fri, Apr 19, 2013 at 11:48:42AM +0800, Fam Zheng wrote:
>> > diff --git a/block/vmdk.c b/block/vmdk.c
>> > index 450a721..5e60940 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_ZG   (1 << 2)
>>
>> Please use a clear name like VMDK4_FLAG_ZERO_GRAIN.
>>
>> > @@ -81,6 +84,8 @@ typedef struct VmdkExtent {
>> >      bool flat;
>> >      bool compressed;
>> >      bool has_marker;
>> > +    bool has_zero_grain;
>> > +    int version;
>>
>> uint32_t according to the spec.  Please use fixed-size integer types
>> instead of int, long, etc which can change depending on the host
>> architecture.
>
> This is an internal structure holding information for extent, used the
> same way as BDRVVmdkState, there is no direct correspondence to file
> header fields, so I think it should be OK, as `int qcow_version' is also
> found in block/qcow2.h.

What is the benefit of changing the type internally?

Stefan

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

[Fam Zheng]

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(-)

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;
 
-- 
1.8.1.4

Re: [Qemu-devel] [PATCH 3/5] vmdk: Add option to create zeroed-grain image

[Stefan Hajnoczi]

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.

[Qemu-devel] [PATCH 4/5] vmdk: change magic number to macro

[Fam Zheng]

From: Feiran Zheng <feiran.zheng@emc.com>

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 827b35b..5daa9f2 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_ZG   (1 << 2)
@@ -1285,7 +1286,7 @@ 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_ZG : 0);
     header.compressAlgorithm = compress ? VMDK4_COMPRESSION_DEFLATE : 0;
-- 
1.8.1.4

Re: [Qemu-devel] [PATCH 4/5] vmdk: change magic number to macro

[Stefan Hajnoczi]

On Fri, Apr 19, 2013 at 11:48:44AM +0800, Fam Zheng wrote:
> From: Feiran Zheng <feiran.zheng@emc.com>
> 
> 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 827b35b..5daa9f2 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_ZG   (1 << 2)
> @@ -1285,7 +1286,7 @@ 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

Nice :)

[Qemu-devel] [PATCH 5/5] vmdk: add bdrv_co_write_zeroes

[Fam Zheng]

From: Feiran Zheng <feiran.zheng@emc.com>

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 | 63 +++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 50 insertions(+), 13 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 5daa9f2..3055847 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1163,8 +1163,16 @@ static coroutine_fn int vmdk_co_read(BlockDriverState *bs, int64_t sector_num,
     return ret;
 }
 
+/**
+ * params:
+ *  - 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
+ *                  try if it's supported
+ */
 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;
@@ -1220,17 +1228,30 @@ 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;
+                }
+            } 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) == -1) {
+                    return -EIO;
+                }
             }
         }
         nb_sectors -= n;
@@ -1256,7 +1277,22 @@ 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;
 }
@@ -1736,6 +1772,7 @@ 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 5/5] vmdk: add bdrv_co_write_zeroes

[Stefan Hajnoczi]

On Fri, Apr 19, 2013 at 11:48:45AM +0800, Fam Zheng wrote:
> From: Feiran Zheng <feiran.zheng@emc.com>
> 
> 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 | 63 +++++++++++++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 50 insertions(+), 13 deletions(-)

Do existing qemu-iotests zero write tests cases cover this?  Do you need
to add vmdk to their list of supported formats?

Stefan

Re: [Qemu-devel] [PATCH 5/5] vmdk: add bdrv_co_write_zeroes

[Fam Zheng]

On Fri, 04/19 11:12, Stefan Hajnoczi wrote:
> On Fri, Apr 19, 2013 at 11:48:45AM +0800, Fam Zheng wrote:
> > From: Feiran Zheng <feiran.zheng@emc.com>
> > 
> > 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 | 63 +++++++++++++++++++++++++++++++++++++++++++++++-------------
> >  1 file changed, 50 insertions(+), 13 deletions(-)
> 
> Do existing qemu-iotests zero write tests cases cover this?  Do you need
> to add vmdk to their list of supported formats?

I guess they cover and has include vmdk already, need to double check
correctness of both side and fix the multiple extents cases
(twoGbMaxExtent{Sparse,Flat}).

This patch can't properly handle metadata update for zero write, will
fix in next version.

-- 
Fam