linux-ext4 - Re: [PATCH v1 19/22] e2fsck: check inline

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Message-ID: <20131012092243.GH14971@birch.djwong.org>
Date:	Sat, 12 Oct 2013 02:22:43 -0700
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	linux-ext4@...r.kernel.org, "Theodore Ts'o" <tytso@....edu>,
	Zheng Liu <wenqing.lz@...bao.com>
Subject: Re: [PATCH v1 19/22] e2fsck: check inline_data in pass3

On Sat, Oct 12, 2013 at 05:17:55PM +0800, Zheng Liu wrote:
> On Sat, Oct 12, 2013 at 02:09:35AM -0700, Darrick J. Wong wrote:
> > On Sat, Oct 12, 2013 at 05:06:35PM +0800, Zheng Liu wrote:
> > > On Fri, Oct 11, 2013 at 05:54:10PM -0700, Darrick J. Wong wrote:
> > > > On Fri, Aug 02, 2013 at 05:49:46PM +0800, Zheng Liu wrote:
> > > > > From: Zheng Liu <wenqing.lz@...bao.com>
> > > > > 
> > > > > In e2fsck_expand_directory() we don't handle a dir with inline data
> > > > > because when this function is called the directory inode shouldn't
> > > > > contains inline data.
> > > > > 
> > > > > Signed-off-by: Theodore Ts'o <tytso@....edu>
> > > > > Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
> > > > > ---
> > > > >  e2fsck/pass3.c  |   12 ++++++++++++
> > > > >  e2fsck/rehash.c |    3 ++-
> > > > >  2 files changed, 14 insertions(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/e2fsck/pass3.c b/e2fsck/pass3.c
> > > > > index a379e9b..5052345 100644
> > > > > --- a/e2fsck/pass3.c
> > > > > +++ b/e2fsck/pass3.c
> > > > > @@ -787,6 +787,18 @@ errcode_t e2fsck_expand_directory(e2fsck_t ctx, ext2_ino_t dir,
> > > > >  	es.ctx = ctx;
> > > > >  	es.dir = dir;
> > > > >  
> > > > > +	/*
> > > > > +	 * 'lost+found' dir shouldn't contains inline data.  So we
> > > > > +	 * need to clear this flag.
> > > > > +	 */
> > > > > +	if (ext2fs_inode_has_inline_data(fs, dir)) {
> > > > > +		retval = ext2fs_read_inode(fs, dir, &inode);
> > > > > +		if (retval)
> > > > > +			return retval;
> > > > > +		inode.i_flags &= ~EXT4_INLINE_DATA_FL;
> > > > > +		e2fsck_write_inode(ctx, dir, &inode, "clear inline_data flag");
> > > > > +	}
> > > > > +
> > > > >  	retval = ext2fs_block_iterate3(fs, dir, BLOCK_FLAG_APPEND,
> > > > >  				       0, expand_dir_proc, &es);
> > > > 
> > > > Are you saying that lost+found can have inline_data set yet i_blocks is
> > > > actually a block map/extent head?  Or are we supposed to zero i_blocks?
> > > > 
> > > > If we clear EXT4_INLINE_DATA_FL and then try to iterate blocks, are we setting
> > > > ourselves up to read (formerly inline) dirents as a block map and iterate it?
> > > > 
> > > > Shouldn't we care if the inode write fails?
> > > 
> > > lost+found dir shouldn't have inline_data flag because this is a special
> > > directory that it is preallocated some blocks when it is created because
> > > we need to avoid to allocate some blocks for it when we check a file
> > > system using e2fsck.  So we need to clear inline_data flag if this dir
> > > has this flag.
> > 
> > How does get that flag in the first place?
> 
> Technically, it shouldn't get this flag.  Think about it again, it seems
> that we don't need to handle this because it couldn't happen.

Hmm.  Maybe there should be an explicit entry and fix_problem() for this
condition?  I think there's some function in e2fsck that specifically messes
with lost+found, but I'm going to bed before the parts of my brain that form
English sentences really crashes. 8)

Though I suppose since we're rehashing directories anyway, there might be
no point in pestering the user more.

--D
> 
>                                                 - Zheng
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