From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu block <qemu-block@nongnu.org>
Cc: qemu-devel <qemu-devel@nongnu.org>, Max Reitz <mreitz@redhat.com>,
Kevin Wolf <kwolf@redhat.com>, "Denis V. Lunev" <den@openvz.org>,
Eric Blake <eblake@redhat.com>
Subject: Re: What prevents discarding a cluster during rewrite?
Date: Tue, 23 Feb 2021 00:42:42 +0300 [thread overview]
Message-ID: <21d6f4e3-1512-50b3-d2a0-7969a49f18bb@virtuozzo.com> (raw)
In-Reply-To: <198596cd-4867-3da5-cd8f-68c1c570a52b@virtuozzo.com>
23.02.2021 00:30, Vladimir Sementsov-Ogievskiy wrote:
> Hi all!
>
> Thinking of how to prevent dereferencing to zero (and discard) of host cluster during flush of compressed cache (which I'm working on now), I have a question.. What prevents it for normal writes?
>
I have no idea about why didn't it fail for years.. May be, I'm missing something?
I have idea of fixing: increase the refcount of host cluster before write to data_file (it's important to increase refacount in same s->lock critical section where we get host_offset) and dereference it after write.. It should help. Any thoughts?
--
Best regards,
Vladimir
next prev parent reply other threads:[~2021-02-22 21:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 21:30 What prevents discarding a cluster during rewrite? Vladimir Sementsov-Ogievskiy
2021-02-22 21:42 ` Vladimir Sementsov-Ogievskiy [this message]
2021-02-23 10:35 ` Kevin Wolf
2021-02-23 15:23 ` Vladimir Sementsov-Ogievskiy
2021-02-23 16:29 ` Kevin Wolf
2021-02-24 6:04 ` Vladimir Sementsov-Ogievskiy
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