linux-ext4 - Re: question about i_dtime being used as an orphan list pointer

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Message-ID: <20100825224830.GK4453@thunk.org>
Date:	Wed, 25 Aug 2010 18:48:30 -0400
From:	Ted Ts'o <tytso@....edu>
To:	Vitali Lovich <vlovich@...il.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: question about i_dtime being used as an orphan list pointer

On Wed, Aug 25, 2010 at 02:25:37PM -0700, Vitali Lovich wrote:
> > For a long-term fix, it probably would make sense to patch ext3/ext4
> > so that when we delete a file, and the current time is less than
> > number of inodes, that we set dtime to 0xffffffff.
>
> Is the i_dtime actually used at all?  Could we just patch it to always
> set that as the i_dtime always?  I grepped the source, & no one is
> actually using the i_dtime field.

It's not used by the kernel, but it is used occasionally by people who
are trouble shooting file systems, and want to know when a particular
inode was deleted.  So a local hack to always set i_dtime to ~0 would
not be horrible.  But something which sets i_dtime to the system time,
unless this would cause confusion with an orphaned inode linked list,
in which case ~0 is used instead, is probably a cleaner fix.

   	      	    	 	     	      	- Ted
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