From: Joe Thornber <thornber@redhat.com>
To: monty <monty_pavel@sina.com>
Cc: dm-devel@redhat.com
Subject: Re: dm thin: data block's ref count is not zero but not belong to any device.
Date: Thu, 27 Sep 2018 15:25:26 +0100 [thread overview]
Message-ID: <20180927142526.GB29590@reti> (raw)
In-Reply-To: <20180926031317.GA20632@yyp.\x02>
On Tue, Sep 25, 2018 at 11:13:17PM -0400, monty wrote:
>
> Hi! I met a problem of dm-thin: a thin-pool has no volumes but its
> nr_free_blocks_data is not zero. I guess the scene of this problem like:
> a. create a thin volume thin01, size is 10GB;
> b. write 10GB to thin01;
> c. create a snapshot thin01-snap, orig is thin01;
> d. write 10GB to thin01-snap;
> e. for a data block of thin01-snap, which will be written by user, will
> experience following steps:
> 1. alloc a data block m firstly;
> 2. wirte data to data block m;
> 3. bio callback and assign data block m to thin01-snap.
> If power loss happens between step 2 and step 3, data block will not
> belong to any device but its ref count is not zero.
> Is it a problem? How to solve this problem?
Yes, there are a couple of ways this can happen, a dump and restore of
the metadata will repair it.
- Joe
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
next parent reply other threads:[~2018-09-27 14:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180926031317.GA20632@yyp.\x02>
2018-09-27 14:25 ` Joe Thornber [this message]
2018-09-26 3:13 dm thin: data block's ref count is not zero but not belong to any device monty
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