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

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

[Shantanu Goel]

[-- Attachment #1: Type: text/plain, Size: 979 bytes --]

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

------------------------------------------------------------------------------
This message is intended only for the personal and confidential use of the
designated recipient(s) named above.  If you are not the intended recipient of
this message you are hereby notified that any review, dissemination,
distribution or copying of this message is strictly prohibited.  This
communication is for information purposes only and should not be regarded as
an offer to sell or as a solicitation of an offer to buy any financial
product, an official confirmation of any transaction, or as an official
statement of Lehman Brothers.  Email transmission cannot be guaranteed to be
secure or error-free.  Therefore, we do not represent that this information is
complete or accurate and it should not be relied upon as such.  All
information is subject to change without notice.

[-- Attachment #2: [NFS PATCH] 2.6.0-test10 Invalidate cached inode attributes after rename --]
[-- Type: message/rfc822, Size: 2022 bytes --]

From: "Shantanu Goel" <Shantanu.Goel@lehman.com>
To: nfs@lists.sourceforge.net
Subject: [NFS PATCH] 2.6.0-test10 Invalidate cached inode attributes after rename
Date: Wed, 26 Nov 2003 14:41:45 -0500
Message-ID: <3FC501F9.1050306@lehman.com>

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:

Re: [Fwd: [NFS PATCH] 2.6.0-test10 Invalidate cached inode attributes after rename]

[Trond Myklebust]

>>>>> " " == Shantanu Goel <Shantanu.Goel@lehman.com> writes:

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


It's not a critical bugfix. It will make it in, but not while the
current code-freeze is in place.

Cheers,
  Trond

Re: [Fwd: [NFS PATCH] 2.6.0-test10 Invalidate cached inode attributes after rename]

[Shantanu Goel]

BTW, this also affects 2.4 kernels (e.g. RedHat's AS3 kernel) which 
include your CTO patches that aren't in the upstream kernels yet.

Thanks,
Shantanu

Trond Myklebust wrote:

>>>>>>" " == Shantanu Goel <Shantanu.Goel@lehman.com> writes:
>>>>>>            
>>>>>>
>
>     > I initially mailed this to the NFS mailing list on
>     > sourceforge.net but it doesn't seem to have made it through.
>
>
>It's not a critical bugfix. It will make it in, but not while the
>current code-freeze is in place.
>
>Cheers,
>  Trond
>
>  
>



------------------------------------------------------------------------------
This message is intended only for the personal and confidential use of the
designated recipient(s) named above.  If you are not the intended recipient of
this message you are hereby notified that any review, dissemination,
distribution or copying of this message is strictly prohibited.  This
communication is for information purposes only and should not be regarded as
an offer to sell or as a solicitation of an offer to buy any financial
product, an official confirmation of any transaction, or as an official
statement of Lehman Brothers.  Email transmission cannot be guaranteed to be
secure or error-free.  Therefore, we do not represent that this information is
complete or accurate and it should not be relied upon as such.  All
information is subject to change without notice.

Re: [Fwd: [NFS PATCH] 2.6.0-test10 Invalidate cached inode attributes after rename]

[Trond Myklebust]

>>>>> " " == Shantanu Goel <Shantanu.Goel@lehman.com> writes:

     > BTW, this also affects 2.4 kernels (e.g. RedHat's AS3 kernel)
     > which include your CTO patches that aren't in the upstream
     > kernels yet.

AFAIK Steve Dickson is already aware of the need for this particular
patch for the AS3 kernel. He was one of the people that brought it to
my attention a couple of weeks ago.

Cheers,
  Trond