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Re: [PATCH v3 04/16] qcow2: Keep unknown extra snapshot data
From: |
Max Reitz |
Subject: |
Re: [PATCH v3 04/16] qcow2: Keep unknown extra snapshot data |
Date: |
Mon, 14 Oct 2019 10:46:24 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0 |
On 11.10.19 18:20, Eric Blake wrote:
> On 10/11/19 10:28 AM, Max Reitz wrote:
>> The qcow2 specification says to ignore unknown extra data fields in
>> snapshot table entries. Currently, we discard it whenever we update the
>> image, which is a bit different from "ignore".
>>
>> This patch makes the qcow2 driver keep all unknown extra data fields
>> when updating an image's snapshot table.
>>
>> Signed-off-by: Max Reitz <address@hidden>
>> Reviewed-by: Eric Blake <address@hidden>
>> ---
>
>> /* Bitmap header extension constraints */
>> #define QCOW2_MAX_BITMAPS 65535
>> #define QCOW2_MAX_BITMAP_DIRECTORY_SIZE (1024 * QCOW2_MAX_BITMAPS)
>> @@ -181,6 +184,8 @@ typedef struct QCowSnapshot {
>> uint32_t date_sec;
>> uint32_t date_nsec;
>> uint64_t vm_clock_nsec;
>> + uint32_t extra_data_size;
>> + void *unknown_extra_data; /* Extra data past
>> QCowSnapshotExtraData */
>
> Would it be worth a comment change:
>
> uint32_t extra_data_size; /* Size of all extra data, including
> QCowSnapshotExtraData */
> void *unknown_extra_data; /* Data beyond QCowSnapshotExtraData, if any */
>
> Either way, R-b stands.
Can’t hurt. Well, except that extra_data_size may or may not include
QCowSnapshotExtraData, because maybe it isn’t fully present in the image.
Max
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- [PATCH v3 00/16] qcow2: Let check -r all repair some snapshot bits, Max Reitz, 2019/10/11
- [PATCH v3 01/16] include: Move endof() up from hw/virtio/virtio.h, Max Reitz, 2019/10/11
- [PATCH v3 02/16] qcow2: Use endof(), Max Reitz, 2019/10/11
- [PATCH v3 03/16] qcow2: Add Error ** to qcow2_read_snapshots(), Max Reitz, 2019/10/11
- [PATCH v3 04/16] qcow2: Keep unknown extra snapshot data, Max Reitz, 2019/10/11
- [PATCH v3 05/16] qcow2: Make qcow2_write_snapshots() public, Max Reitz, 2019/10/11
- [PATCH v3 06/16] qcow2: Put qcow2_upgrade() into its own function, Max Reitz, 2019/10/11
- [PATCH v3 07/16] qcow2: Write v3-compliant snapshot list on upgrade, Max Reitz, 2019/10/11
[PATCH v3 08/16] qcow2: Separate qcow2_check_read_snapshot_table(), Max Reitz, 2019/10/11
[PATCH v3 09/16] qcow2: Add qcow2_check_fix_snapshot_table(), Max Reitz, 2019/10/11
[PATCH v3 10/16] qcow2: Fix broken snapshot table entries, Max Reitz, 2019/10/11