linux-ext4 - Re: [PATCH 1/4] ext4: Fix data exposure after a crash

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Message-ID: <20160425102458.GC4365@quack2.suse.cz>
Date:	Mon, 25 Apr 2016 12:24:58 +0200
From:	Jan Kara <jack@...e.cz>
To:	Theodore Ts'o <tytso@....edu>
Cc:	Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org,
	Weller.Huang@...bosch.com, stable@...r.kernel.org
Subject: Re: [PATCH 1/4] ext4: Fix data exposure after a crash

On Sun 24-04-16 00:55:51, Ted Tso wrote:
> I had to add a !IS_NOQUOTA check:
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 576f64a..250c2df 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -693,6 +693,7 @@ out_sem:
>  		if (map->m_flags & EXT4_MAP_NEW &&
>  		    !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
>  		    !(flags & EXT4_GET_BLOCKS_ZERO) &&
> +		    !IS_NOQUOTA(inode) &&
>  		    ext4_should_order_data(inode)) {
>  			ret = ext4_jbd2_file_inode(handle, inode);
>  			if (ret)
> 
> 
> In order to prevent crashes when writing to the quota file (see
> below).

Good catch. The fix looks correct to me, thanks for fixing this up. Since
data for quota files is actually journalled, it may be actually a cleaner
fix to reflect this in ext4_inode_journal_mode() and thus
ext4_should_order_data() would catch this case. But this has more potential
for breakage elsewhere so I will do that as a separate cleanup patch.

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