NFS Client patch

[Craig Soules]

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Hello,

I hope that I am sending this to the appropriate people.  I have been
working on a project known as Self-Securing Storage here at Carnegie
Mellon University.  We have developed our storage server to act as an
NFSv2 server, and have been using the Linux NFSv2 client to do our
benchmarking. I have run across a small problem with the 2.4
implementation of the Linux NFSv2 client.

The problem is in the readdir() operation.  The current cookie for a given
readdir operation is being stored in the file descriptor.  The problem is
that it is not being reset to 0 if a change has been made to the
directory as is indicated in the NFSv2 spec.  This problem is often
seen when doing an operation such as rm -rf to a large directory tree due
to the asynchronous remove operation that has been implemented.

This has not traditionally been a problem for Linux because in ext2 the
cookie is the offset into the directory of the next entry.  If a file
is deleted in that directory during the readdir() operation, it has no
effect since ext2 does lazy directory compaction.

Our system does automatic directory compaction through the use of a tree
structure, and so the cookie needs to be invalidated.  Also, any other
file system whicih does immediate directory compaction would require this.

I have attached my proposed modifications to the end of this file.  They
have been tested under 2.4.5.

Please let me know if there is anything more I need to do, or if you have
any questions.  I would really like to get this proper behavior into the
kernel.

Thanks,
Craig Soules

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