linux-ext4 - Re: [PATCH] ext4: Make fsync to sync parent dir in no-journal for real this time

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Date:	Thu, 2 Apr 2015 23:45:38 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Lukas Czerner <lczerner@...hat.com>
Cc:	linux-ext4@...r.kernel.org, Frank Mayhar <fmayhar@...gle.com>
Subject: Re: [PATCH] ext4: Make fsync to sync parent dir in no-journal for
 real this time

On Mon, Feb 23, 2015 at 02:16:36PM +0100, Lukas Czerner wrote:
> Previously commit 14ece1028b3ed53ffec1b1213ffc6acaf79ad77c added a
> support for for syncing parent directory of newly created inodes to make
> sure that the inode is not lost after a power failure in no-journal
> mode.
> 
> However this does not work in majority of cases, namely:
>  - if the directory has inline data
>  - if the directory is already indexed
>  - if the directory already has at least one block and:
> 	- the new entry fits into it
> 	- or we've successfully converted it to indexed
> 
> So in those cases we might lose the inode entirely even after fsync in
> the no-journal mode. This also includes ext2 default mode obviously.
> 
> I've noticed this while running xfstest generic/321 and even though the
> test should fail (we need to run fsck after a crash in no-journal mode)
> I could not find a newly created entries even when if it was fsynced
> before.
> 
> Fix this by adjusting the ext4_add_entry() successful exit paths to set
> the inode EXT4_STATE_NEWENTRY so that fsync has the chance to fsync the
> parent directory as well.
> 
> Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> Cc: Frank Mayhar <fmayhar@...gle.com>

Thanks, applied.

						- Ted
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