Description of problem: Specific NFS server setup results on BUG on linux nfs client: nfs_follow_mountpoint BUG_ON(IS_ROOT(dentry)) the configuration is the following: tc27.qa.sw.ru -- NFS server (FC8) ts27.qa.sw.ru -- NFS client (RHEL5) Server configuration is the following: [root@tc27 proc]# cat /etc/exports /nfs_share ts27.qa.sw.ru(rw,no_root_squash,no_subtree_check,crossmnt) /nfs_share/boo *(rw,no_root_squash,no_subtree_check) [root@tc27 proc]# cat /proc/mounts /dev/mapper/vzvg-vz /nfs_share ext3 rw,data=ordered 0 0 /dev/sda1 /nfs_share/boo ext3 rw,data=ordered 0 0 Issue can be reproduced by the following script on CLIENT SIDE: [root@ts27 ~]# cat sub-mounts.sh #!/bin/bash echo 65535 > /proc/sys/sunrpc/nfs_debug echo 65535 > /proc/sys/sunrpc/rpc_debug stat -f /mnt/nfs/ | grep -q 'Type: nfs' || mount -v -t nfs tc27:/nfs_share /mnt/nfs -o vers=3,tcp,hard,nointr { ls /mnt/nfs ls /mnt/nfs/boo } >/dev/null echo =========================== grep nfs /proc/mounts umount /mnt/nfs/ This BUG_ON happens due to improper behavior of rpc.mountd process on the nfs server. This is proven by the following file on the server: [root@tc27 proc]# cat /proc/net/rpc/nfsd.fh/content #domain fsidtype fsid [path] *,ts27 0 0x0000fd0000000002 /nfs_share *,ts27 0 0x0100080000000002 /nfs_share As you can see it contains /nfs_share instead of /nfs_share/boo for 0x0100080000000002 fsid. Version-Release number of selected component (if applicable): nfs-utils-1.1.0-6.fc8 Actual results: BUG_ON on client side on nfs submount lookup because of incorrect content of /proc/net/rpc/nfsd.fh/content file Expected results: correct content of /proc/net/rpc/nfsd.fh/content file
The patch posted to the linux-nfs mailing list: Unfortunately, BUG_ON(IS_ROOT(dentry)) can happen inside nfs_follow_mountpoint with NFS running Fedora 8 using a specific setup. https://bugzilla.redhat.com/show_bug.cgi?id=458622 So, the situation should be handled on NFS client gracefully. Signed-off-by: Denis V. Lunev <den> CC: Trond Myklebust <Trond.Myklebust> CC: J. Bruce Fields <bfields> --- fs/nfs/namespace.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c index 66df08d..4f11c13 100644 --- a/fs/nfs/namespace.c +++ b/fs/nfs/namespace.c @@ -105,7 +105,10 @@ static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd) dprintk("--> nfs_follow_mountpoint()\n"); - BUG_ON(IS_ROOT(dentry)); + err = -ESTALE; + if (IS_ROOT(dentry)) + goto out_err; + dprintk("%s: enter\n", __func__); dput(nd->path.dentry); nd->path.dentry = dget(dentry);
I've created a separate bug for RHEL5 NFS client panic https://bugzilla.redhat.com/show_bug.cgi?id=458774
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Fedora 8 changed to end-of-life (EOL) status on 2009-01-07. Fedora 8 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. Thank you for reporting this bug and we are sorry it could not be fixed.