linux-ext4 - Re: [PATCH v2 1/2] ext4: protect i_disksize update by i_data

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Message-ID: <20180322154537.GH2852@thunk.org>
Date:   Thu, 22 Mar 2018 11:45:37 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Eryu Guan <guaneryu@...il.com>
Cc:     linux-ext4@...r.kernel.org, Jan Kara <jack@...e.cz>
Subject: Re: [PATCH v2 1/2] ext4: protect i_disksize update by i_data_sem in
 direct write path

On Mon, Mar 12, 2018 at 11:21:55PM +0800, Eryu Guan wrote:
> i_disksize update should be protected by i_data_sem, by either taking
> the lock explicitly or by using ext4_update_i_disksize() helper. But the
> i_disksize updates in ext4_direct_IO_write() are not protected at all,
> which may be racing with i_disksize updates in writeback path in
> delalloc buffer write path.
> 
> This is found by code inspection, and I didn't hit any i_disksize
> corruption due to this bug. Thanks to Jan Kara for catching this bug and
> suggesting the fix!
> 
> Reported-by: Jan Kara <jack@...e.cz>
> Suggested-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Eryu Guan <guaneryu@...il.com>

Applied, thanks.

					- Ted