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

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Date:	Sun, 28 Jul 2013 22:15:32 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Theodore Ts'o <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 Sun, 2013-07-28 at 07:40 -0400, Theodore Ts'o wrote:
> On Sat, Jul 27, 2013 at 10:33:31PM +0100, Ben Hutchings wrote:
> > > --- 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.
> 
> Nice catch.  Yup, that's a problem.  I'll fix this upstream and mark
> it cc:stable.
> 
> Until this goes upstream stable kernel maintainers can either: (a) fix
> up this patch by making the line read "err == -ENOMEM", (b) hold back
> this patch until the companion patch to fix this goes upstream, or (c)
> apply this now, since it's otherwise harmless and it does add error
> checking to the ext4_ext_remove_space() call.

We do need that second fix upstream first.  I agree that this seems to
fix a bug and doesn't make the ENOMEM case worse.  If this is applicable
to 3.2.y (I think it isn't but haven't checked yet) then I'll go with
(c).

Ben.

-- 
Ben Hutchings
All extremists should be taken out and shot.

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