[Fwd: [NFS PATCH] 2.6.0-test10 Invalidate cached inodeattributes after rename]

[Shantanu Goel]

I initially mailed this to the NFS mailing list on sourceforge.net but 
it doesn't seem to have made it through.

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> --- Begin Message ---
> Hi Trond et al,
>
> The following one line patch invalidates the attributes of the 
> underlying inode when a file is renamed.  Some filesystems update ctime 
> upon rename().  One such filesystem is ext3, and a comment in the 
> relevant code there indicates this is true with other Unix filesystems 
> as well.
> The following problem was observed on Fedora Core 1 running a stock 
> kernel.org 2.6.0-test10.
> The server is running Solaris 2.8 but I have verified the same issue 
> exists with a server running Linix 2.4.22.  These operations a done via 
> a Perl script.
>
> 1. Check out a CVS repository into an NFS mounted directory.
> 2. Move files from CVS working directory into another directory in the 
> same filesystem.
> 3. Tar up the resultant directory.
> 4. Tar prints lots of "file changed after we read it" messages.
>
> Tar obtains ctime via stat() before reading the file and compares it to 
> the ctime obtained via fstat() after having read the file.  The two 
> differ because the intervening open() forces an attribute refresh due to 
> CTO consistency at which time ctime is updated.  Forcing a cache 
> invalidation during rename() eliminates this particular scenario.
>
> Thanks,
> Shantanu
>
> --- 2.6.0-test10/fs/nfs/dir.c.~1~    2003-10-17 17:43:11.000000000 -0400
> +++ 2.6.0-test10/fs/nfs/dir.c    2003-11-26 12:42:27.000000000 -0500
> @@ -1257,6 +1257,7 @@
>
>     nfs_zap_caches(new_dir);
>     nfs_zap_caches(old_dir);
> +    NFS_CACHEINV(old_inode);
>     error = NFS_PROTO(old_dir)->rename(old_dir, &old_dentry->d_name,
>                        new_dir, &new_dentry->d_name);
> out:
>
>
> --- End Message ---