From: Matthew Treinish <treinish@linux.vnet.ibm.com>
To: linux-nfs@vger.kernel.org
Cc: treinish@linux.vnet.ibm.com
Subject: [PATCH/RFC v2 0/7] Volatile Filehandle Client-side Support
Date: Fri,  9 Dec 2011 10:23:25 -0500
Message-Id: <1323444212-9855-1-git-send-email-treinish@linux.vnet.ibm.com>
Sender: linux-nfs-owner@vger.kernel.org

This patch series implements client side support for volatile file handle
recovery (RFC 3530 section 4.2 and 4.3) with walk back using the dcache. To
test the client you either need a server that supports volatile file handles or
you can hard code the Linux server to output NFS4ERR_FHEXPIRED instead of
NFSERR_STALE.

The approach used here for recovery is to perform lookups for each file handle
that receives a FHEXPIRED error. If the lookup also fails with FHEXPIRED using
the dcache, it will recursively walk back to the root of the mount, and recover
that using get_root.

Simple testing has shown that this approach works and will correctly recover
from a FHEXPIRED error code. However, the current implementation uses
d_obtain_alias if a nfs4_proc function is only given an inode. When hardlinks
are involved, this results in getting a path, but not necessarily a path which
the user has access, which might lead to permission issues.

As Trond pointed out on the first posting originally it was unable to recover
from FHEXPIRED in state_recovery or rpciod since lookup operations started in
either thread context would not have access to perform the lookup. So this
version attempts to fix this by passing an rpc_cred to vfh_lookup. Then the
credential is added to the lookup's rpc message so that the recovery lookup
will have access. The only thing I am unsure of now is where I pass credential
from for rpciod and state recovery contexts.

v2:
- Added rpc_cred passing to the vfh lookup and added handling of access errors
  on the lookup

Matthew Treinish (7):
  New mount option for volatile filehandle recovery
  Added support for FH_EXPIRE_TYPE attribute.
  Add VFS objects from nfs4_proc calls into nfs4_exception.
  Save root file handle in nfs_server.
  Added VFH FHEXPIRED recovery functions.
  Perform recovery on both inodes for rename.
  Added error handling for NFS4ERR_FHEXPIRED

 fs/nfs/client.c           |    3 +
 fs/nfs/getroot.c          |    7 +
 fs/nfs/nfs4_fs.h          |    3 +
 fs/nfs/nfs4proc.c         |  287 ++++++++++++++++++++++++++++++++++++++++-----
 fs/nfs/nfs4xdr.c          |   27 +++++
 fs/nfs/super.c            |    6 +
 include/linux/nfs_fs_sb.h |    2 +
 include/linux/nfs_mount.h |    1 +
 include/linux/nfs_xdr.h   |    1 +
 9 files changed, 308 insertions(+), 29 deletions(-)

-- 
1.7.4.4