Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-pb0-f46.google.com ([209.85.160.46]:63814 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753766Ab2K3ATy (ORCPT ); Thu, 29 Nov 2012 19:19:54 -0500 Received: by mail-pb0-f46.google.com with SMTP id wy7so20078pbc.19 for ; Thu, 29 Nov 2012 16:19:53 -0800 (PST) Message-ID: <50B7FBA7.2030300@gaikai.com> Date: Thu, 29 Nov 2012 16:19:51 -0800 From: Patrick McLean MIME-Version: 1.0 To: Al Viro CC: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Trond Myklebust , linux-nfs@vger.kernel.org Subject: Re: Regression with initramfs and nfsroot (appears to be in the dcache) References: <20121129213316.GU4939@ZenIV.linux.org.uk> <20121129222109.GW4939@ZenIV.linux.org.uk> <50B7E759.9070007@gaikai.com> <20121129234326.GX4939@ZenIV.linux.org.uk> In-Reply-To: <20121129234326.GX4939@ZenIV.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: On 29/11/12 03:43 PM, Al Viro wrote: > On Thu, Nov 29, 2012 at 02:53:13PM -0800, Patrick McLean wrote: >> On 29/11/12 02:21 PM, Al Viro wrote: >>> On Thu, Nov 29, 2012 at 02:06:22PM -0800, Patrick McLean wrote: >>> >>>> I have a trivial reproducer and am happy to help debug in any way that >>>> I can. That patch seems to fix the problem, and produces these >>>> warnings in dmesg: >>> >>> OK... So we have differing entry->fh and NFS_FH(dentry->d_inode). Something >>> like >>> static void dump_fh(const struct nfs_fh *fh) >>> { >>> int i; >>> printk(KERN_INFO "FH(%d)", fh->size); >>> for (i = 0; i < fh->size; i++) >>> printk(KERN_CONT "%c%02x", i ? ' ' : '[', fh->data[i]); >>> printk(KERN_CONT "]\n"); >>> } >>> with dump_fh(entry->fh); dump_fh(NFS_FH(dentry->d_inode)); added next to >>> that WARN_ON(1) would probably be interesting. And probably would make >>> sense to print filename->name as well, to see which files it is about. > >> [ 8.821584] FH(0)] >> [ 8.821586] FH(36)[01 00 07 01 89 00 00 00 00 00 00 00 e1 21 fe c4 9e 38 44 dc bf 1b d5 95 d6 76 d6 d9 a7 3c 1b 80 33 38 e3 62] >> [ 8.821601] filename: proc > > *whoa* > > So we have zero entry->fh->size? No wonder it doesn't match... Which NFS > version it is? entry->fh->size is set by nfs[34]_decode_dirent(). This is nfs v3 over TCP on Linus git at commit e9296e89b85604862bd9ec2d54dc43edad775c0d with nfs-utils-1.2.6 userspace. > NFS folks: any ideas on best way to debug it? The brute-force way would be > to capture all NFS traffic with tcpdump and see what's going on, but that > would be a lot of work... > > Looks like we have READDIRPLUS attempted and succeeded, but fhandle was not > given. Result: nfs_prime_dcache() is doing blind d_drop() on perfectly > valid dentries, no matter how busy. >