linux-kernel - Re: [ 71/79] ext4: fix error handling in ext4_ext

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Date:	Sat, 27 Jul 2013 22:33:31 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Theodore Tso <tytso@....edu>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [ 71/79] ext4: fix error handling in ext4_ext_truncate()

On Fri, 2013-07-26 at 13:48 -0700, Greg Kroah-Hartman wrote:
> 3.10-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Theodore Ts'o <tytso@....edu>
> 
> commit 8acd5e9b1217e58a57124d9e225afa12efeae20d upstream.
> 
> Previously ext4_ext_truncate() was ignoring potential error returns
> from ext4_es_remove_extent() and ext4_ext_remove_space().  This can
> lead to the on-diks extent tree and the extent status tree cache
> getting out of sync, which is particuarlly bad, and can lead to file
> system corruption and potential data loss.
> 
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> 
> ---
>  fs/ext4/extents.c |   11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4386,9 +4386,20 @@ void ext4_ext_truncate(handle_t *handle,
>  
>  	last_block = (inode->i_size + sb->s_blocksize - 1)
>  			>> EXT4_BLOCK_SIZE_BITS(sb);
> +retry:
>  	err = ext4_es_remove_extent(inode, last_block,
>  				    EXT_MAX_BLOCKS - last_block);
> +	if (err == ENOMEM) {

Positive ENOMEM?!  It looks like this value is bubbled up from
__es_insert_extent() which returns the usual negative error codes.

Ben.

> +		cond_resched();
> +		congestion_wait(BLK_RW_ASYNC, HZ/50);
> +		goto retry;
> +	}
> +	if (err) {
> +		ext4_std_error(inode->i_sb, err);
> +		return;
> +	}
>  	err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
> +	ext4_std_error(inode->i_sb, err);
>  }
>  
>  static void ext4_falloc_update_inode(struct inode *inode,
> 

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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