linux-ext4 - Re: [PATCH 3/6] ext4: Do not clear EOFBLOCKS

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Message-ID: <87obx5i8r8.fsf@dmbot.sw.ru>
Date:	Tue, 25 Oct 2011 15:57:31 +0400
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	Ted Ts'o <tytso@....edu>
Cc:	linux-ext4@...r.kernel.org, achender@...ux.vnet.ibm.com
Subject: Re: [PATCH 3/6] ext4: Do not clear EOFBLOCKS_FL too soon

On Tue, 25 Oct 2011 04:18:34 -0400, Ted Ts'o <tytso@....edu> wrote:
> On Fri, Oct 21, 2011 at 01:08:56AM +0400, Dmitry Monakhov wrote:
> > ext4_ext_insert_extent() may fail due to number of reasons (ENOSPC)
> > so let's update eof flag only after extent was successfully inserted.
> > 
> > Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
> 
> The problem with this patch is that if the check_eofblocks_fl() fails,
> the patch jumps to out: and doesn't undo the block allocation and
> extent tree manipulation.
check_eofblocks_fl may fail only due to ext4_journal_get_write_access
or ext4_mark_iloc_dirty, this means that something serious happen,
so it is very unlikely we can undo block allocation.
> 
> I suspect a better way of solving this problem is to keep the existing
> order, but to save the state of eofblocks flag, and if
> ext4_ext_insert_extent() fails, to restore the state of the eofblocks
> flag before jumping to the exit routine.
Yes. This is definitely looks better, will redo.
> 
> 					- Ted
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