linux-ext4 - Re: [PATCH 14/38] fallthru: ext2 fallthru support

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Message-ID: <20100806171640.GC16599@shell>
Date:	Fri, 6 Aug 2010 13:16:40 -0400
From:	Valerie Aurora <vaurora@...hat.com>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	viro@...iv.linux.org.uk, jblunck@...e.de, hch@...radead.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 14/38] fallthru: ext2 fallthru support

On Fri, Aug 06, 2010 at 10:15:14AM +0200, Miklos Szeredi wrote:
> On Thu, 5 Aug 2010, Valerie Aurora wrote:
> > On Thu, Aug 05, 2010 at 12:36:55PM +0200, Miklos Szeredi wrote:
> > > On Wed, 4 Aug 2010, Valerie Aurora wrote:
> > > > --zYM0uCDKw75PZbzx
> > > > Content-Type: text/plain; charset=us-ascii
> > > > Content-Disposition: inline
> > > > 
> > > > On Wed, Aug 04, 2010 at 04:44:10PM +0200, Miklos Szeredi wrote:
> > > > > On Tue, 15 Jun 2010, Valerie Aurora wrote:
> > > > > > Add support for fallthru directory entries to ext2.
> > > > > 
> > > > > If a previously used ext2 filesystem with is mounted again then
> > > > > fallthroughs don't appear to work as expected.  Stat returns ENOENT
> > > > > for these entries.
> > > > > 
> > > > > Can't see anything obviously wrong with the code.
> > > > 
> > > > Hm, I wrote one test case for this that worked (attached).  Can you
> > > > give me more details on your test case?  Thanks,
> > 
> > Cool, thanks.  Yes, I suppose the fallthrus should be ignored if they
> > don't fall through to anything.
> 
> That's not the case here.  They _should_ fall through to ext3.img, yet
> apparently after ovl.img being mounted again they don't seem to work.

Oh, "mmount -b 8" == "mount -o union".  Is this the mmount from mtools
or something else?

> Note, ovl.img starts out as a completely empty filesystem.
> 
> The difference between your test case and mine mitght be that yours
> not only reads the directory but stats the files as well, while mine
> does not.

Okay, I'll experiment more and see what I can do.

-VAL

> Thanks,
> Miklos
> 
> 
> > 
> > > uml:~# mount -oloop -r ext3-2.img /mnt/img/
> > > uml:~# mount -oloop -r ext3.img /mnt/img/
> > > uml:~# losetup -f ovl.img 
> > > uml:~# mmount -b 8 -t ext2 /dev/loop2 /mnt/img/
> > > uml:~# "ls" /mnt/img
> > > bunion  lost+found  union
> > > uml:~# "ls" /mnt/img/union
> > > 1  2  3
> > > uml:~# "ls" /mnt/img/union/1
> > > a  x
> > > uml:~# umount /mnt/img/
> > > uml:~# mmount -b 8 -t ext2 /dev/loop2 /mnt/img/
> > > uml:~# ls -l /mnt/img/  
> > > total 14
> > > drwxr-xr-x 2 root root  1024 Aug  5 09:56 bunion
> > > drwx------ 2 root root 12288 Aug  5 09:41 lost+found
> > > drwxr-xr-x 3 root root  1024 Aug  5 09:56 union
> > > uml:~# ls -l /mnt/img/union/
> > > ls: cannot access /mnt/img/union/3: No such file or directory
> > > ls: cannot access /mnt/img/union/2: No such file or directory
> > > total 1
> > > drwxr-xr-x 2 root root 1024 Aug  5 09:56 1
> > > ?????????? ? ?    ?       ?            ? 2
> > > ?????????? ? ?    ?       ?            ? 3
> > > uml:~# ls -l /mnt/img/union/1
> > > ls: cannot access /mnt/img/union/1/a: No such file or directory
> > > ls: cannot access /mnt/img/union/1/x: No such file or directory
> > > total 0
> > > ?????????? ? ? ? ?            ? a
> > > ?????????? ? ? ? ?            ? x
> > > uml:~# 
> > > 
> > > Thanks,
> > > Miklos
> > 
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