linux-kernel - Re: [PATCH] xfs: revert to double-buffering readdir

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20071203151141.GB18082@infradead.org>
Date:	Mon, 3 Dec 2007 15:11:41 +0000
From:	Christoph Hellwig <hch@...radead.org>
To:	Stephen Lord <lord@....org>
Cc:	Timothy Shimmin <tes@....com>,
	Christoph Hellwig <hch@...radead.org>,
	Chris Wedgwood <cw@...f.org>, linux-xfs@....sgi.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] xfs: revert to double-buffering readdir

On Fri, Nov 30, 2007 at 04:36:25PM -0600, Stephen Lord wrote:
> Wow, was it really that long ago!
>
> Looks like the readdir is in the bowels of the btree code when filldir gets 
> called
> here, there are probably locks on several buffers in the btree at this 
> point. This
> will only show up for large directories I bet.

Chris saw it with block-form directories.  I've verified it works fine
with short-form directories, and the leaf code looks like it could
happen aswell.  I also remember gfs2 running into a similar problem.

> The xfs readdir code has the complete xfs inode number in its hands at this 
> point
> (filldir is not necessarily getting all the bits of it). All we are doing 
> the lookup
> for really is to get the inode number back again so we can get the inode
> and get the attributes. Rather dumb really. There has got to be a way of
> doing a callout structure here so that the inode number can be pushed
> through filldir and back into an fs specific call. The fs then can do a 
> lookup
> by id - which is what it does most of the time for resolving nfs handles
> anyway. Should be more efficient than the current scheme.

Yes, a lot more efficient.  But it means adding a new operation for use
by the nfs server.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/