From: John Snow <jsnow@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-devel@nongnu.org
Cc: kwolf@redhat.com, pbonzini@redhat.com,
Vladimir Sementsov-Ogievskiy <vsementsov@parallels.com>,
stefanha@redhat.com, den@openvz.org
Subject: Re: [Qemu-devel] [PATCH 6/8] qcow2: add autoclear bit for dirty bitmaps
Date: Thu, 11 Jun 2015 12:36:01 -0400 [thread overview]
Message-ID: <5579B8F1.4040606@redhat.com> (raw)
In-Reply-To: <557967C1.1010009@virtuozzo.com>
On 06/11/2015 06:49 AM, Vladimir Sementsov-Ogievskiy wrote:
> On 11.06.2015 02:42, John Snow wrote:
>>
>> On 06/08/2015 11:21 AM, Vladimir Sementsov-Ogievskiy wrote:
>>> From: Vladimir Sementsov-Ogievskiy <vsementsov@parallels.com>
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>> ---
>>> block/qcow2-dirty-bitmap.c | 5 +++++
>>> block/qcow2.c | 13 +++++++++++--
>>> block/qcow2.h | 9 +++++++++
>>> 3 files changed, 25 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/block/qcow2-dirty-bitmap.c b/block/qcow2-dirty-bitmap.c
>>> index db83112..686a121 100644
>>> --- a/block/qcow2-dirty-bitmap.c
>>> +++ b/block/qcow2-dirty-bitmap.c
>>> @@ -188,6 +188,11 @@ static int
>>> qcow2_write_dirty_bitmaps(BlockDriverState *bs)
>>> s->dirty_bitmaps_offset = dirty_bitmaps_offset;
>>> s->dirty_bitmaps_size = dirty_bitmaps_size;
>>> + if (s->nb_dirty_bitmaps > 0) {
>>> + s->autoclear_features |= QCOW2_AUTOCLEAR_DIRTY_BITMAPS;
>>> + } else {
>>> + s->autoclear_features &= ~QCOW2_AUTOCLEAR_DIRTY_BITMAPS;
>>> + }
>>> ret = qcow2_update_header(bs);
>>> if (ret < 0) {
>>> fprintf(stderr, "Could not update qcow2 header\n");
>>> diff --git a/block/qcow2.c b/block/qcow2.c
>>> index 406e55d..f85a55a 100644
>>> --- a/block/qcow2.c
>>> +++ b/block/qcow2.c
>>> @@ -182,6 +182,14 @@ static int
>>> qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
>>> return ret;
>>> }
>>> + if (!(s->autoclear_features &
>>> QCOW2_AUTOCLEAR_DIRTY_BITMAPS) &&
>>> + s->nb_dirty_bitmaps > 0) {
>>> + ret = qcow2_delete_all_dirty_bitmaps(bs, errp);
>>> + if (ret < 0) {
>>> + return ret;
>>> + }
>>> + }
>>> +
>>> #ifdef DEBUG_EXT
>>> printf("Qcow2: Got dirty bitmaps extension:"
>>> " offset=%" PRIu64 " nb_bitmaps=%" PRIu32 "\n",
>>> @@ -928,8 +936,9 @@ static int qcow2_open(BlockDriverState *bs, QDict
>>> *options, int flags,
>>> }
>>> /* Clear unknown autoclear feature bits */
>>> - if (!bs->read_only && !(flags & BDRV_O_INCOMING) &&
>>> s->autoclear_features) {
>>> - s->autoclear_features = 0;
>>> + if (!bs->read_only && !(flags & BDRV_O_INCOMING) &&
>>> + (s->autoclear_features & ~QCOW2_AUTOCLEAR_MASK)) {
>>> + s->autoclear_features |= QCOW2_AUTOCLEAR_MASK;
>> Like Stefan already mentioned, fixing this |= to &= will fix iotest 036,
>> which is otherwise broken by this patch.
>>
>>> ret = qcow2_update_header(bs);
>>> if (ret < 0) {
>>> error_setg_errno(errp, -ret, "Could not update qcow2
>>> header");
>>> diff --git a/block/qcow2.h b/block/qcow2.h
>>> index b5e576c..14bd6f9 100644
>>> --- a/block/qcow2.h
>>> +++ b/block/qcow2.h
>>> @@ -215,6 +215,15 @@ enum {
>>> QCOW2_COMPAT_FEAT_MASK = QCOW2_COMPAT_LAZY_REFCOUNTS,
>>> };
>>> +/* Autoclear feature bits */
>>> +enum {
>>> + QCOW2_AUTOCLEAR_DIRTY_BITMAPS_BITNR = 0,
>>> + QCOW2_AUTOCLEAR_DIRTY_BITMAPS =
>>> + 1 << QCOW2_AUTOCLEAR_DIRTY_BITMAPS_BITNR,
>>> +
>>> + QCOW2_AUTOCLEAR_MASK =
>>> QCOW2_AUTOCLEAR_DIRTY_BITMAPS,
>>> +};
>>> +
>> I find it a little awkward to have an enum with three different kinds of
>> data in it, unless I am reading this incorrectly. (bit position, bit
>> masks, and accumulated bit mask.)
>>
>> Just enumerating the indices is probably sufficient:
>>
>> enum {
>> QCOW2_AUTOCLEAR_BEGIN = 0,
>> QCOW2_AUTOCLEAR_DIRTY_BITMAPS = QCOW2_AUTOCLEAR_BEGIN,
>> ...,
>> QCOW2_AUTOCLEAR_END
>> }
>>
>> and then the QCOW2_AUTOCLEAR_MASK can either be programmatically defined
>> via a function, or just pre-computed as a #define.
>>
>> If you still want the mask definitions, you could do something cheeky
>> like this:
>>
>> #define AUTOCLEAR_MASK(X) (1 << QCOW2_AUTOCLEAR_ ## X)
>>
>> and then you can use things like AUTOCLEAR_MASK(DIRTY_BITMAPS) without
>> having to create and maintain two separate tables if you want both forms
>> easily available.
>
>
> This enum is made like enums for QCOW2_INCOMPAT_* and QCOW2_COMPAT_*,
> which are already in the code... Then, may I make a patch for them too?
> I agree, it is strange solution to put things of different nature to one
> enum.
>
Follow Kevin's lead, here -- It looked strange to me, but it _is_ best
to follow the existing style. I didn't look at the surrounding code too
carefully.
>
>>
>>> enum qcow2_discard_type {
>>> QCOW2_DISCARD_NEVER = 0,
>>> QCOW2_DISCARD_ALWAYS,
>>>
>
>
next prev parent reply other threads:[~2015-06-11 16:36 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-08 15:21 [Qemu-devel] [PATCH v2 RFC 0/8] block: persistent dirty bitmaps Vladimir Sementsov-Ogievskiy
2015-06-08 15:21 ` [Qemu-devel] [PATCH 1/8] spec: add qcow2-dirty-bitmaps specification Vladimir Sementsov-Ogievskiy
2015-06-09 16:01 ` John Snow
2015-06-09 17:03 ` Stefan Hajnoczi
2015-06-10 8:19 ` Vladimir Sementsov-Ogievskiy
2015-06-10 8:49 ` Vladimir Sementsov-Ogievskiy
2015-06-10 13:00 ` Eric Blake
2015-06-11 10:16 ` Vladimir Sementsov-Ogievskiy
2015-06-10 13:24 ` Stefan Hajnoczi
2015-06-11 10:19 ` Vladimir Sementsov-Ogievskiy
2015-06-11 13:03 ` Stefan Hajnoczi
2015-06-11 16:21 ` John Snow
2015-06-12 10:28 ` Stefan Hajnoczi
2015-06-12 15:19 ` John Snow
2015-06-10 15:34 ` Kevin Wolf
2015-06-11 10:25 ` Vladimir Sementsov-Ogievskiy
2015-06-11 16:30 ` John Snow
2015-06-12 8:33 ` Kevin Wolf
2015-08-24 10:46 ` Vladimir Sementsov-Ogievskiy
2015-08-24 13:30 ` Vladimir Sementsov-Ogievskiy
2015-08-24 14:08 ` Vladimir Sementsov-Ogievskiy
2015-08-24 14:04 ` Vladimir Sementsov-Ogievskiy
2015-08-31 22:21 ` Eric Blake
2015-08-31 22:24 ` John Snow
2015-06-08 15:21 ` [Qemu-devel] [PATCH 2/8] qcow2: add dirty-bitmaps feature Vladimir Sementsov-Ogievskiy
2015-06-09 16:52 ` Stefan Hajnoczi
2015-06-10 14:30 ` Stefan Hajnoczi
2015-06-12 19:02 ` John Snow
2015-06-15 14:42 ` Stefan Hajnoczi
2015-06-23 17:57 ` John Snow
2015-06-24 9:39 ` Stefan Hajnoczi
2015-08-14 17:14 ` Vladimir Sementsov-Ogievskiy
2015-08-26 9:09 ` Stefan Hajnoczi
2015-06-11 23:04 ` John Snow
2015-06-15 14:05 ` Vladimir Sementsov-Ogievskiy
2015-06-15 16:53 ` John Snow
2015-06-12 21:55 ` John Snow
2015-08-26 13:15 ` Vladimir Sementsov-Ogievskiy
2015-08-26 14:14 ` Vladimir Sementsov-Ogievskiy
2015-08-27 12:43 ` Vladimir Sementsov-Ogievskiy
2015-06-08 15:21 ` [Qemu-devel] [PATCH 3/8] block: store persistent dirty bitmaps Vladimir Sementsov-Ogievskiy
2015-06-08 15:21 ` [Qemu-devel] [PATCH 4/8] block: add bdrv_load_dirty_bitmap Vladimir Sementsov-Ogievskiy
2015-06-09 16:01 ` Stefan Hajnoczi
2015-06-10 22:33 ` John Snow
2015-06-11 10:41 ` Vladimir Sementsov-Ogievskiy
2015-06-08 15:21 ` [Qemu-devel] [PATCH 5/8] qcow2: add qcow2_dirty_bitmap_delete_all Vladimir Sementsov-Ogievskiy
2015-06-08 15:21 ` [Qemu-devel] [PATCH 6/8] qcow2: add autoclear bit for dirty bitmaps Vladimir Sementsov-Ogievskiy
2015-06-09 15:49 ` Stefan Hajnoczi
2015-06-09 15:50 ` Stefan Hajnoczi
2015-08-27 7:45 ` Vladimir Sementsov-Ogievskiy
2015-08-31 11:06 ` Vladimir Sementsov-Ogievskiy
2015-08-31 22:39 ` Eric Blake
2015-08-31 22:50 ` Eric Blake
2015-06-10 23:42 ` John Snow
2015-06-11 8:35 ` Kevin Wolf
2015-06-11 10:49 ` Vladimir Sementsov-Ogievskiy
2015-06-11 16:36 ` John Snow [this message]
2015-06-08 15:21 ` [Qemu-devel] [PATCH 7/8] qemu: command line option " Vladimir Sementsov-Ogievskiy
2015-06-11 20:57 ` John Snow
2015-06-12 21:49 ` John Snow
2015-06-08 15:21 ` [Qemu-devel] [PATCH 8/8] iotests: test internal persistent dirty bitmap Vladimir Sementsov-Ogievskiy
2015-06-09 16:17 ` Eric Blake
2015-06-10 15:27 ` [Qemu-devel] [PATCH v2 RFC 0/8] block: persistent dirty bitmaps Stefan Hajnoczi
2015-06-11 11:22 ` Vladimir Sementsov-Ogievskiy
2015-06-11 13:14 ` Stefan Hajnoczi
2015-06-11 20:06 ` Stefan Hajnoczi
2015-06-12 9:58 ` Denis V. Lunev
2015-06-12 10:36 ` Stefan Hajnoczi
2015-08-26 6:26 ` Vladimir Sementsov-Ogievskiy
2015-08-26 9:13 ` Stefan Hajnoczi
2015-06-12 19:34 ` John Snow
2015-06-17 14:29 ` Vladimir Sementsov-Ogievskiy
2015-06-24 0:21 ` John Snow
2015-07-08 12:24 ` Vladimir Sementsov-Ogievskiy
2015-07-08 15:21 ` John Snow
2015-08-27 10:08 ` Vladimir Sementsov-Ogievskiy
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