Re: [Qemu-devel] [PATCH v6 04/10] hbitmap: Add hbitmap_copy

Re: [Qemu-devel] [PATCH v6 04/10] hbitmap: Add hbitmap_copy

[Vladimir Sementsov-Ogievskiy]

[-- Attachment #1: Type: text/plain, Size: 702 bytes --]

> +
> +HBitmap *hbitmap_copy(const HBitmap *bitmap)
> +{
> +    int i;
> +    int64_t size;
> +    HBitmap *hb = g_memdup(bitmap, sizeof(struct HBitmap));
> +
> +    size = bitmap->size;
> +    for (i = HBITMAP_LEVELS; i-- > 0; ) {
> +        size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
> +        hb->levels[i] = g_memdup(bitmap->levels[i],
> +                                 size * sizeof(unsigned long));
> +    }
> +
> +    return hb;
> +}

"(size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL" - will be zero iff size == 0. Is it really possible in qemu? If not, we doesn't need MAX(..., 1).
There is similar construction in older "hbitmap_alloc" function.

-- 
Best regards,
Vladimir


[-- Attachment #2: Type: text/html, Size: 1611 bytes --]

[Qemu-devel] [PATCH v6 00/10] block: Incremental backup series

[Fam Zheng]

v6: Rebased v4 of the series on top of qemu.git. (skipping v5 since it was used
    by me as a private sending, for those who received it, the code is the same
    :)

This is the in memory part of the incremental backup feature.

With the added commands, we can create a bitmap on a block backend, from which
point of time all the writes are tracked by the bitmap, marking sectors as
dirty.  Later, we call drive-backup and pass the bitmap to it, to do an
incremental backup.

See the last patch which adds some tests for this use case.

Fam

Fam Zheng (10):
  qapi: Add optional field "name" to block dirty bitmap
  qmp: Add block-dirty-bitmap-add and block-dirty-bitmap-remove
  block: Introduce bdrv_dirty_bitmap_granularity()
  hbitmap: Add hbitmap_copy
  block: Add bdrv_copy_dirty_bitmap and bdrv_reset_dirty_bitmap
  qmp: Add block-dirty-bitmap-enable and block-dirty-bitmap-disable
  qmp: Add support of "dirty-bitmap" sync mode for drive-backup
  qapi: Add transaction support to
    block-dirty-bitmap-{add,enable,disable}
  qmp: Add dirty bitmap 'enabled' field in query-block
  qemu-iotests: Add tests for drive-backup sync=dirty-bitmap

 block-migration.c             |   2 +-
 block.c                       |  82 ++++++++++++++++-
 block/backup.c                |  54 +++++++++++-
 block/mirror.c                |   6 +-
 blockdev.c                    | 198 +++++++++++++++++++++++++++++++++++++++++-
 hmp.c                         |   4 +-
 include/block/block.h         |  15 +++-
 include/block/block_int.h     |   4 +
 include/qemu/hbitmap.h        |   8 ++
 qapi-schema.json              |   5 +-
 qapi/block-core.json          | 120 +++++++++++++++++++++++--
 qmp-commands.hx               |  66 +++++++++++++-
 tests/qemu-iotests/056        |  33 ++++++-
 tests/qemu-iotests/056.out    |   4 +-
 tests/qemu-iotests/iotests.py |   8 ++
 util/hbitmap.c                |  16 ++++
 16 files changed, 603 insertions(+), 22 deletions(-)

-- 
1.9.3

[Qemu-devel] [PATCH v6 04/10] hbitmap: Add hbitmap_copy

[Fam Zheng]

This makes a deep copy of an HBitmap.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 include/qemu/hbitmap.h |  8 ++++++++
 util/hbitmap.c         | 16 ++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index 550d7ce..b645cfc 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -65,6 +65,14 @@ struct HBitmapIter {
 HBitmap *hbitmap_alloc(uint64_t size, int granularity);
 
 /**
+ * hbitmap_copy:
+ * @bitmap: The original bitmap to copy.
+ *
+ * Copy a HBitmap.
+ */
+HBitmap *hbitmap_copy(const HBitmap *bitmap);
+
+/**
  * hbitmap_empty:
  * @hb: HBitmap to operate on.
  *
diff --git a/util/hbitmap.c b/util/hbitmap.c
index b3060e6..78d449e 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -395,3 +395,19 @@ HBitmap *hbitmap_alloc(uint64_t size, int granularity)
     hb->levels[0][0] |= 1UL << (BITS_PER_LONG - 1);
     return hb;
 }
+
+HBitmap *hbitmap_copy(const HBitmap *bitmap)
+{
+    int i;
+    int64_t size;
+    HBitmap *hb = g_memdup(bitmap, sizeof(struct HBitmap));
+
+    size = bitmap->size;
+    for (i = HBITMAP_LEVELS; i-- > 0; ) {
+        size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
+        hb->levels[i] = g_memdup(bitmap->levels[i],
+                                 size * sizeof(unsigned long));
+    }
+
+    return hb;
+}
-- 
1.9.3

Re: [Qemu-devel] [PATCH v6 04/10] hbitmap: Add hbitmap_copy

[Max Reitz]

On 2014-10-30 at 04:22, Fam Zheng wrote:
> This makes a deep copy of an HBitmap.
>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>   include/qemu/hbitmap.h |  8 ++++++++
>   util/hbitmap.c         | 16 ++++++++++++++++
>   2 files changed, 24 insertions(+)
>
> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
> index 550d7ce..b645cfc 100644
> --- a/include/qemu/hbitmap.h
> +++ b/include/qemu/hbitmap.h
> @@ -65,6 +65,14 @@ struct HBitmapIter {
>   HBitmap *hbitmap_alloc(uint64_t size, int granularity);
>   
>   /**
> + * hbitmap_copy:
> + * @bitmap: The original bitmap to copy.
> + *
> + * Copy a HBitmap.
> + */
> +HBitmap *hbitmap_copy(const HBitmap *bitmap);
> +
> +/**
>    * hbitmap_empty:
>    * @hb: HBitmap to operate on.
>    *
> diff --git a/util/hbitmap.c b/util/hbitmap.c
> index b3060e6..78d449e 100644
> --- a/util/hbitmap.c
> +++ b/util/hbitmap.c
> @@ -395,3 +395,19 @@ HBitmap *hbitmap_alloc(uint64_t size, int granularity)
>       hb->levels[0][0] |= 1UL << (BITS_PER_LONG - 1);
>       return hb;
>   }
> +
> +HBitmap *hbitmap_copy(const HBitmap *bitmap)
> +{
> +    int i;
> +    int64_t size;

Why not uint64_t, like HBitmap::size? Not that it matters in practice, I 
hope.

> +    HBitmap *hb = g_memdup(bitmap, sizeof(struct HBitmap));

"struct" can be omitted.

> +
> +    size = bitmap->size;
> +    for (i = HBITMAP_LEVELS; i-- > 0; ) {

Urgh... I'd prefer "for (i = HBITMAP_LEVELS - 1; i >= 0; i--)" though 
yours is correct and shorter.

> +        size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
> +        hb->levels[i] = g_memdup(bitmap->levels[i],
> +                                 size * sizeof(unsigned long));
> +    }
> +
> +    return hb;
> +}

With or without any of the changes:

Reviewed-by: Max Reitz <mreitz@redhat.com>