Re: 2.6.18-rc4-mm1

On Tue, 2006-08-15 at 17:55 +0100, David Howells wrote:
Trond Myklebust <trond.myklebust@xxxxxxxxxx> wrote:

Could you try pulling afresh from the NFS git tree? I've fixed up a couple
of issues in which rpc_pipefs was corrupting the dcache,

Which patches hold those fixes? I'm seeing:

BUG: atomic counter underflow at:
[<c01d5b05>] _atomic_dec_and_lock+0x1d/0x30
[<c0169bd3>] dput+0x22/0x145
[<c8a2f726>] rpc_destroy_client+0xd9/0xee [sunrpc]
[<c8a2f89e>] rpc_shutdown_client+0xea/0xf1 [sunrpc]
[<c8a2f89e>] rpc_shutdown_client+0xea/0xf1 [sunrpc]
[<c886d842>] nfs_free_client+0x95/0xdd [nfs]
[<c886db38>] nfs_free_server+0xa9/0xd9 [nfs]
[<c8873fae>] nfs_kill_super+0xc/0x14 [nfs]
[<c015c033>] deactivate_super+0x4a/0x5d
[<c016df3e>] sys_umount+0x1d3/0x1f1
[<c016ac98>] destroy_inode+0x36/0x45
[<c0169bd3>] dput+0x22/0x145
[<c0157889>] __fput+0x146/0x170
[<c016cf48>] mntput_no_expire+0x11/0x59
[<c016df73>] sys_oldumount+0x17/0x1a
[<c0102b3f>] syscall_call+0x7/0xb
=======================

And I'm wondering if that's due to that problem.

I've applied the patch to fix the resource counting that's at the head of your
git tree.

See attached mail. Alex confirmed that it fixes the corruption problems
he is seeing.

Cheers,
Trond
--- Begin Message --- On Mon, 2006-08-14 at 16:34 -0400, Alex Polvi wrote:
On 8/14/06, Alex Polvi <polvi@xxxxxxxxxx> wrote:
Here is another fix. It is quite silly, but clnt->cl_auth is set to
NULL in rpc_destroy_client(), then eventually referenced in
gss_release_pipe() via rpc_rmdir(). Simply removing the clnt->cl_auth
= NULL from clnt.c fixes the issue. I'm still trying to understand the
subsystem, but it seems like rpc_rmdir is being correctly called to
clean up because of the weirdness with umount -l and the nfs server
being turned on and off. Does that seem correct? Or is this still just
covering up some other part of the code being sloppy cleaning up?

Also, I just want to make it clear that I do not think this is the
proper fix. It is just pointing out that we intentionally set cl_auth
to NULL, then reference it.

OK. I think I've finally managed to clean up the various interactions
with rpc_pipefs. I've uploaded a series of patches on the NFS client
website. See

http://client.linux-nfs.org/Linux-2.6.x/2.6.18-rc4/

The relevant patches are

linux-2.6.18-006-fix_rpc_unlink.dif:

From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

SUNRPC: make rpc_unlink() take a dentry argument instead of a
path

Signe-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

linux-2.6.18-007-fix_rpc_rmdir.dif:

From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

NFS: clean up rpc_rmdir

Make it take a dentry argument instead of a path

Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

linux-2.6.18-008-fix_rpc_unlink_rmdir_2.dif:

From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

SUNRPC: rpc_unlink() must check for unhashed dentries

A prior call to rpc_depopulate() by rpc_rmdir() on the parent
directory may have already called simple_unlink() on this entry.
Add the same check to rpc_rmdir(). Also remove a redundant call
to rpc_close_pipes() in rpc_rmdir.

Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

linux-2.6.18-009-fix_rpc_unlink_rmdir_3.dif:

From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

SUNRPC: Fix dentry refcounting issues with users of rpc_pipefs

rpc_unlink() and rpc_rmdir() will dput the dentry reference for
you.

Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

----

In addition, there is one patch that is needed in order to fix up a
related issue in the function nfs_alloc_client(), which was introduced
by David Howells' NFS superblock sharing patches.

Cheers,
Trond

--- End Message ---

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