Re: [Qemu-devel] [PATCH 04/17] qcow2: Dirty Bitmaps Ext: structs and consts

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

On 06.10.2015 23:16, John Snow wrote:
>
> On 09/05/2015 12:43 PM, Vladimir Sementsov-Ogievskiy wrote:
>> Add data structures and constraints accordingly to docs/specs/qcow2.txt
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>   block/Makefile.objs        |  2 +-
>>   block/qcow2-dirty-bitmap.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>>   block/qcow2.h              | 28 ++++++++++++++++++++++++++++
>>   3 files changed, 71 insertions(+), 1 deletion(-)
>>   create mode 100644 block/qcow2-dirty-bitmap.c
>>
>> diff --git a/block/Makefile.objs b/block/Makefile.objs
>> index 58ef2ef..c6e1f4b 100644
>> --- a/block/Makefile.objs
>> +++ b/block/Makefile.objs
>> @@ -1,5 +1,5 @@
>>   block-obj-y += raw_bsd.o qcow.o vdi.o vmdk.o cloop.o bochs.o vpc.o vvfat.o
>> -block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o
>> +block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o qcow2-dirty-bitmap.o
>>   block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
>>   block-obj-y += qed-check.o
>>   block-obj-$(CONFIG_VHDX) += vhdx.o vhdx-endian.o vhdx-log.o
>> diff --git a/block/qcow2-dirty-bitmap.c b/block/qcow2-dirty-bitmap.c
>> new file mode 100644
>> index 0000000..fd4e0ef
>> --- /dev/null
>> +++ b/block/qcow2-dirty-bitmap.c
>> @@ -0,0 +1,42 @@
>> +/*
>> + * Dirty bitmaps for the QCOW version 2 format
>> + *
>> + * Copyright (c) 2014-2015 Vladimir Sementsov-Ogievskiy
>> + *
>> + * This file is derived from qcow2-snapshot.c, original copyright:
>> + * Copyright (c) 2004-2006 Fabrice Bellard
>> + *
>> + * Permission is hereby granted, free of charge, to any person obtaining a copy
>> + * of this software and associated documentation files (the "Software"), to deal
>> + * in the Software without restriction, including without limitation the rights
>> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
>> + * copies of the Software, and to permit persons to whom the Software is
>> + * furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice shall be included in
>> + * all copies or substantial portions of the Software.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
>> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
>> + * THE SOFTWARE.
>> + */
>> +
>> +/* NOTICE: DBM here means Dirty Bitmap and used as a namespace for _internal_
>> + * constants. Please do not use this _internal_ abbreviation for other needs
>> + * and/or outside of this file. */
>> +
>> +/* Dirty Bitmap Directory Enrty constraints */
>> +#define DBM_MAX_TABLE_SIZE 0x8000000
>> +#define DBM_MAX_PHYS_SIZE 0x20000000 /* 512 mb */
>> +#define DBM_MAX_GRANULARITY_BITS 63
>> +#define DBM_MAX_NAME_SIZE 1023
>> +
>> +/* Dirty Bitmap Directory Enrty flags */
>> +#define DBM_RESERVED_FLAGS 0xffffffff
>> +
>> +/* bits [0, 8] U [56, 63] are reserved */
>> +#define DBM_TABLE_ENTRY_RESERVED_MASK 0xff000000000001ff
>> diff --git a/block/qcow2.h b/block/qcow2.h
>> index 72e1328..a2a5d4a 100644
>> --- a/block/qcow2.h
>> +++ b/block/qcow2.h
>> @@ -52,6 +52,10 @@
>>    * space for snapshot names and IDs */
>>   #define QCOW_MAX_SNAPSHOTS_SIZE (1024 * QCOW_MAX_SNAPSHOTS)
>>   
>> +/* Dirty Bitmap Header Extension constraints */
>> +#define QCOW_MAX_DIRTY_BITMAPS 65536
>> +#define QCOW_MAX_DIRTY_BITMAP_DIRECTORY_SIZE (1024 * QCOW_MAX_DIRTY_BITMAPS)
>> +
>>   /* indicate that the refcount of the referenced cluster is exactly one. */
>>   #define QCOW_OFLAG_COPIED     (1ULL << 63)
>>   /* indicate that the cluster is compressed (they never have the copied flag) */
>> @@ -141,6 +145,19 @@ typedef struct QEMU_PACKED QCowSnapshotHeader {
>>       /* name follows  */
>>   } QCowSnapshotHeader;
>>   
>> +typedef struct QEMU_PACKED QCowDirtyBitmapHeader {
>> +    /* header is 8 byte aligned */
>> +    uint64_t dirty_bitmap_table_offset;
>> +    uint64_t nb_virtual_bits;
>> +
>> +    uint32_t dirty_bitmap_table_size;
>> +    uint32_t granularity_bits;
>> +
>> +    uint32_t flags;
> looks like DBM_RESERVED_FLAGS was meant to apply to this field, but I
> think the mask is incorrect and should be 0xfffffff0.

I've decided to make patches consistent, so DBM_RESERVED_FLAGS is 
changed in following patches, where flags added.

>
>> +    uint16_t name_size;
>> +    /* name follows  */
>> +} QCowDirtyBitmapHeader;
>> +
>>   typedef struct QEMU_PACKED QCowSnapshotExtraData {
>>       uint64_t vm_state_size_large;
>>       uint64_t disk_size;
>> @@ -159,6 +176,11 @@ typedef struct QCowSnapshot {
>>       uint64_t vm_clock_nsec;
>>   } QCowSnapshot;
>>   
>> +typedef struct QCowDirtyBitmap {
>> +    uint64_t offset;
>> +    char *name;
>> +} QCowDirtyBitmap;
>> +
>>   struct Qcow2Cache;
>>   typedef struct Qcow2Cache Qcow2Cache;
>>   
>> @@ -221,6 +243,12 @@ typedef uint64_t Qcow2GetRefcountFunc(const void *refcount_array,
>>   typedef void Qcow2SetRefcountFunc(void *refcount_array,
>>                                     uint64_t index, uint64_t value);
>>   
>> +typedef struct Qcow2DirtyBitmapHeaderExt {
>> +    uint32_t nb_dirty_bitmaps;
>> +    uint32_t dirty_bitmap_directory_size;
>> +    uint64_t dirty_bitmap_directory_offset;
>> +} QEMU_PACKED Qcow2DirtyBitmapHeaderExt;
>> +
>>   typedef struct BDRVQcowState {
>>       int cluster_bits;
>>       int cluster_size;
>>


-- 
Best regards,
Vladimir