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Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitm
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex |
Date: |
Tue, 27 Jun 2017 14:52:29 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 |
On 27/06/2017 11:47, Vladimir Sementsov-Ogievskiy wrote:
> bdrv_enable_dirty_bitmap - writes to the list, it changes 'disabled'
> field. So it requires both BQL and dirty_bitmap_mutex? But the comment
> says only about BQL.
This one is interesting. There could be a concurrent call to
bdrv_set_dirty, indeed. I'll send a patch.
> Also, for example, if I want to create a new bitmap and than somehow
> change it, should I do it like this:
>
> bdrv_create_dirty_bitmap(...)
>
> bdrv_dirty_bitmaps_lock(bs)
>
> bitmap = bdrv_find_dirty_bitmap(bs, name)
>
> <some changes>
>
> bdrv_dirty_bitmaps_unlock(bs)
>
> - because we can't now trust the pointer returned by
> bdrv_create_dirty_bitmap, as it releases bitmap lock before return.
If you have the big QEMU lock (you do if you are in the QEMU monitor),
you are protected from changes to the list of bitmaps.
Paolo
- [Qemu-devel] [PATCH 13/19] block: protect tracked_requests and flush_queue with reqs_lock, (continued)
- [Qemu-devel] [PATCH 13/19] block: protect tracked_requests and flush_queue with reqs_lock, Paolo Bonzini, 2017/06/05
- [Qemu-devel] [PATCH 10/19] util: add stats64 module, Paolo Bonzini, 2017/06/05
- [Qemu-devel] [PATCH 14/19] block: introduce dirty_bitmap_mutex, Paolo Bonzini, 2017/06/05
- [Qemu-devel] [PATCH 17/19] block: introduce block_account_one_io, Paolo Bonzini, 2017/06/05
- [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Paolo Bonzini, 2017/06/05
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Vladimir Sementsov-Ogievskiy, 2017/06/26
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Paolo Bonzini, 2017/06/26
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Vladimir Sementsov-Ogievskiy, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Paolo Bonzini, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Vladimir Sementsov-Ogievskiy, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Vladimir Sementsov-Ogievskiy, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Paolo Bonzini, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Vladimir Sementsov-Ogievskiy, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Paolo Bonzini, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Vladimir Sementsov-Ogievskiy, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Paolo Bonzini, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Vladimir Sementsov-Ogievskiy, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Vladimir Sementsov-Ogievskiy, 2017/06/27
- Re: [Qemu-devel] [PATCH 16/19] block: protect modification of dirty bitmaps with a mutex, Paolo Bonzini, 2017/06/27
[Qemu-devel] [PATCH 15/19] migration/block: reset dirty bitmap before reading, Paolo Bonzini, 2017/06/05