linux-ext4 - Re: query about truncate and orphan list

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Message-ID: <20120829131758.GA21169@quack.suse.cz>
Date:	Wed, 29 Aug 2012 15:17:58 +0200
From:	Jan Kara <jack@...e.cz>
To:	Ashish Sangwan <ashishsangwan2@...il.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: query about truncate and orphan list

On Wed 29-08-12 14:52:22, Ashish Sangwan wrote:
> I have a query about orphan list and truncate.
> Currently these steps are performed in ext4_ext_truncate():
> a) Start journal handle.
> b) add inode to orphan list.
> c) i_disksize is updated and inode is mark dirty.
> d) actual truncate happen.
> e) remove inode from orphan list.
> f) handle stop.
> 
> If system crash during step d) will i_disksize is actually updated on disk?
> AFAIK i_disksize might be updated on the journal but not on its
> original location because the transaction is not commited yet.
  Yes, that can happen.

> If this is the case than what is the use of re-starting truncate
> operation while processing orphan inode list?
  Because it can be on disk (noone guarantees when a transaction commits)
and in that case we have to perform the truncate because some of the blocks
might have been already freed by a transaction which is also committed.

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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