From: Andreas Dilger <adilger@clusterfs.com>
To: David Malone <dwmalone@maths.tcd.ie>
Cc: linux-xfs@oss.sgi.com, linux-kernel@vger.kernel.org
Subject: Re: Directory link count wrapping on Linux/XFS/i386?
Date: Wed, 30 Mar 2005 13:06:01 -0700 [thread overview]
Message-ID: <20050330200601.GG1753@schnapps.adilger.int> (raw)
In-Reply-To: <200503302043.aa27223@salmon.maths.tcd.ie>
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On Mar 30, 2005 20:43 +0100, David Malone wrote:
> It seems that internally xfs uses a 32 bit field for the link count,
> and the stat64 syscalls use a 32 bit field. These fields are copied
> via the vattr structure in xfs_vnode.h, which uses a nlink_t for
> the link count. However, in the kernel, I think this field is
> actually of type __kernel_nlink_t which seems to be 16 bits on many
> platforms.
>
> I've tested this on an i386 2.6.11 kernel and it seems that the
> link count presented to userland wraps after 65536 subdirectories.
> This naturally doesn't let you screw up the filesystem or anything,
> but it does let you can hide files from find/fts, as demonstrated
> below.
The correct fix, used for reiserfs (and a patch for ext3 also) is to
set i_nlink = 1 in case the filesystem count has wrapped. When nlink==1
the fts/find code no longer optimizes subdirectory traversal and checks
each entries filetype to see if it should recurse.
Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.
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next prev parent reply other threads:[~2005-03-30 20:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-30 19:43 David Malone
2005-03-30 20:06 ` Andreas Dilger [this message]
2005-03-31 0:42 ` Nathan Scott
2005-03-31 2:25 ` Nathan Scott
2005-03-31 6:23 ` Jan Engelhardt
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