From a71ee337b31271e701f689d544b6153b75609bc5 Mon Sep 17 00:00:00 2001 From: Suresh Jayaraman Date: Tue, 10 Mar 2009 20:33:21 -0400 Subject: [PATCH] NFS: Handle -ESTALE error in access() Hi Trond, I have been looking at a bugreport where trying to open applications on KDE on a NFS mounted home fails temporarily. There have been multiple reports on different kernel versions pointing to this common issue: http://bugzilla.kernel.org/show_bug.cgi?id=12557 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/269954 http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=508866.html This issue can be reproducible consistently by doing this on a NFS mounted home (KDE): 1. Open 2 xterm sessions 2. From one of the xterm session, do "ssh -X " 3. "stat ~/.Xauthority" on the remote SSH session 4. Close the two xterm sessions 5. On the server do a "stat ~/.Xauthority" 6. Now on the client, try to open xterm This will fail. Even if the filehandle had become stale, the NFS client should invalidate the cache/inode and should repeat LOOKUP. Looking at the packet capture when the failure occurs shows that there were two subsequent ACCESS() calls with the same filehandle and both fails with -ESTALE error. I have tested the fix below. Now the client issue a LOOKUP after the ACCESS() call fails with -ESTALE. If all this makes sense to you, can you consider this for inclusion? Thanks, If the server returns an -ESTALE error due to stale filehandle in response to an ACCESS() call, we need to invalidate the cache and inode so that LOOKUP() can be retried. Without this change, the nfs client retries ACCESS() with the same filehandle, fails again and could lead to temporary failure of applications running on nfs mounted home. Signed-off-by: Suresh Jayaraman Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index e35c8199f82f..672368f865ca 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1892,8 +1892,14 @@ static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask) cache.cred = cred; cache.jiffies = jiffies; status = NFS_PROTO(inode)->access(inode, &cache); - if (status != 0) + if (status != 0) { + if (status == -ESTALE) { + nfs_zap_caches(inode); + if (!S_ISDIR(inode->i_mode)) + set_bit(NFS_INO_STALE, &NFS_I(inode)->flags); + } return status; + } nfs_access_add_cache(inode, &cache); out: if ((mask & ~cache.mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)