Introduce a mechanism for probing a server to determine if an FSID
is present or absent.

The on-the-wire compound is different between minor version 0 and 1.
Minor version 0 appends a RENEW operation to identify which client
ID is probing.  Minor version 1 has a SEQUENCE operation in the
compound which effectively carries the same information.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

When a server returns NFS4ERR_MOVED during a delegation recall,
trigger the new migration recovery logic in the state manager.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

When a server returns NFS4ERR_MOVED, trigger the new migration
recovery logic in the state manager.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

I'm going to use this exit label also for migration recovery
failures.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Clean up.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Migration recovery and state recovery must be serialized, so handle
both in the state manager thread.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

NFS_SB() returns the pointer to an nfs_server struct, given a
pointer to a super_block.  But we have no way to go back the other
way.

Add a super_block backpointer field so that, given an nfs_server
struct, it is easy to get to the filesystem's root dentry.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The nfs4_proc_fs_locations() function is invoked during referral
processing to perform a GETATTR(fs_locations) on an object's parent
directory in order to discover the target of the referral.  It
performs a LOOKUP in the compound, so the client needs to know the
parent's file handle a priori.

Unfortunately this function is not adequate for handling migration
recovery.  We need to probe fs_locations information on an FSID, but
there's no parent directory available for many operations that
can return NFS4ERR_MOVED.

Another subtlety: recovering from NFS4ERR_LEASE_MOVED is a process
of walking over a list of known FSIDs that reside on the server, and
probing whether they have migrated.  Once the server has detected
that the client has probed all migrated file systems, it stops
returning NFS4ERR_LEASE_MOVED.

A minor version zero server needs to know what client ID is
requesting fs_locations information so it can clear the flag that
forces it to continue returning NFS4ERR_LEASE_MOVED.  This flag is
set per client ID and per FSID.  However, the client ID is not an
argument of either the PUTFH or GETATTR operations.  Later minor
versions have client ID information embedded in the compound's
SEQUENCE operation.

Therefore, by convention, minor version zero clients send a RENEW
operation in the same compound as the GETATTR(fs_locations), since
RENEW's one argument is a clientid4.  This allows a minor version
zero server to identify correctly the client that is probing for a
migration.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Allow code in nfsv4.ko to use _nfs_display_fhandle().
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The differences between minor version 0 and minor version 1
migration will be abstracted by the addition of a set of migration
recovery ops.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Introduce functions that can walk through an array of returned
fs_locations information and connect a transport to one of the
destination servers listed therein.

Note that NFS minor version 1 introduces "fs_locations_info" which
extends the locations array sorting criteria available to clients.
This is not supported yet.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

New function nfs4_update_server() moves an nfs_server to a different
nfs_client.  This is done as part of migration recovery.

Though it may be appealing to think of them as the same thing,
migration recovery is not the same as following a referral.

For a referral, the client has not descended into the file system
yet: it has no nfs_server, no super block, no inodes or open state.
It is enough to simply instantiate the nfs_server and super block,
and perform a referral mount.

For a migration, however, we have all of those things already, and
they have to be moved to a different nfs_client.  No local namespace
changes are needed here.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Cached opens have already been handled by _nfs4_opendata_reclaim_to_nfs4_state
and can safely skip being reprocessed, but must still call update_open_stateid
to make sure that all active fmodes are recovered.
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Cc: stable@vger.kernel.org # 3.7.x: f494a607: NFSv4: fix NULL dereference
Cc: stable@vger.kernel.org # 3.7.x: a43ec98b: NFSv4: don't fail on missin
Cc: stable@vger.kernel.org # 3.7.x
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Currently, if the call to nfs_refresh_inode fails, then we end up leaking
a reference count, due to the call to nfs4_get_open_state.
While we're at it, replace nfs4_get_open_state with a simple call to
atomic_inc(); there is no need to do a full lookup of the struct nfs_state
since it is passed as an argument in the struct nfs4_opendata, and
is already assigned to the variable 'state'.

Cc: stable@vger.kernel.org # 3.7.x: a43ec98b: NFSv4: don't fail on missing
Cc: stable@vger.kernel.org # 3.7.x
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

This is an unneeded check that could cause the client to fail to recover
opens.
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

_nfs4_opendata_reclaim_to_nfs4_state doesn't expect to see a cached
open CLAIM_PREVIOUS, but this can happen. An example is when there are
RDWR openers and RDONLY openers on a delegation stateid. The recovery
path will first try an open CLAIM_PREVIOUS for the RDWR openers, this
marks the delegation as not needing RECLAIM anymore, so the open
CLAIM_PREVIOUS for the RDONLY openers will not actually send an rpc.

The NULL dereference is due to _nfs4_opendata_reclaim_to_nfs4_state
returning PTR_ERR(rpc_status) when !rpc_done. When the open is
cached, rpc_done == 0 and rpc_status == 0, thus
_nfs4_opendata_reclaim_to_nfs4_state returns NULL - this is unexpected
by callers of nfs4_opendata_to_nfs4_state().

This can be reproduced easily by opening the same file two times on an
NFSv4.0 mount with delegations enabled, once as RDWR and once as RDONLY then
sleeping for a long time.  While the files are held open, kick off state
recovery and this NULL dereference will be hit every time.

An example OOPS:

[   65.003602] BUG: unable to handle kernel NULL pointer dereference at 00000000
00000030
[   65.005312] IP: [<ffffffffa037d6ee>] __nfs4_close+0x1e/0x160 [nfsv4]
[   65.006820] PGD 7b0ea067 PUD 791ff067 PMD 0
[   65.008075] Oops: 0000 [#1] SMP
[   65.008802] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache
snd_ens1371 gameport nfsd snd_rawmidi snd_ac97_codec ac97_bus btusb snd_seq snd
_seq_device snd_pcm ppdev bluetooth auth_rpcgss coretemp snd_page_alloc crc32_pc
lmul crc32c_intel ghash_clmulni_intel microcode rfkill nfs_acl vmw_balloon serio
_raw snd_timer lockd parport_pc e1000 snd soundcore parport i2c_piix4 shpchp vmw
_vmci sunrpc ata_generic mperf pata_acpi mptspi vmwgfx ttm scsi_transport_spi dr
m mptscsih mptbase i2c_core
[   65.018684] CPU: 0 PID: 473 Comm: 192.168.10.85-m Not tainted 3.11.2-201.fc19
.x86_64 #1
[   65.020113] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop
Reference Platform, BIOS 6.00 07/31/2013
[   65.022012] task: ffff88003707e320 ti: ffff88007b906000 task.ti: ffff88007b906000
[   65.023414] RIP: 0010:[<ffffffffa037d6ee>]  [<ffffffffa037d6ee>] __nfs4_close+0x1e/0x160 [nfsv4]
[   65.025079] RSP: 0018:ffff88007b907d10  EFLAGS: 00010246
[   65.026042] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   65.027321] RDX: 0000000000000050 RSI: 0000000000000001 RDI: 0000000000000000
[   65.028691] RBP: ffff88007b907d38 R08: 0000000000016f60 R09: 0000000000000000
[   65.029990] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
[   65.031295] R13: 0000000000000050 R14: 0000000000000000 R15: 0000000000000001
[   65.032527] FS:  0000000000000000(0000) GS:ffff88007f600000(0000) knlGS:0000000000000000
[   65.033981] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   65.035177] CR2: 0000000000000030 CR3: 000000007b27f000 CR4: 00000000000407f0
[   65.036568] Stack:
[   65.037011]  0000000000000000 0000000000000001 ffff88007b907d90 ffff88007a880220
[   65.038472]  ffff88007b768de8 ffff88007b907d48 ffffffffa037e4a5 ffff88007b907d80
[   65.039935]  ffffffffa036a6c8 ffff880037020e40 ffff88007a880000 ffff880037020e40
[   65.041468] Call Trace:
[   65.042050]  [<ffffffffa037e4a5>] nfs4_close_state+0x15/0x20 [nfsv4]
[   65.043209]  [<ffffffffa036a6c8>] nfs4_open_recover_helper+0x148/0x1f0 [nfsv4]
[   65.044529]  [<ffffffffa036a886>] nfs4_open_recover+0x116/0x150 [nfsv4]
[   65.045730]  [<ffffffffa036d98d>] nfs4_open_reclaim+0xad/0x150 [nfsv4]
[   65.046905]  [<ffffffffa037d979>] nfs4_do_reclaim+0x149/0x5f0 [nfsv4]
[   65.048071]  [<ffffffffa037e1dc>] nfs4_run_state_manager+0x3bc/0x670 [nfsv4]
[   65.049436]  [<ffffffffa037de20>] ? nfs4_do_reclaim+0x5f0/0x5f0 [nfsv4]
[   65.050686]  [<ffffffffa037de20>] ? nfs4_do_reclaim+0x5f0/0x5f0 [nfsv4]
[   65.051943]  [<ffffffff81088640>] kthread+0xc0/0xd0
[   65.052831]  [<ffffffff81088580>] ? insert_kthread_work+0x40/0x40
[   65.054697]  [<ffffffff8165686c>] ret_from_fork+0x7c/0xb0
[   65.056396]  [<ffffffff81088580>] ? insert_kthread_work+0x40/0x40
[   65.058208] Code: 5c 41 5d 5d c3 0f 1f 84 00 00 00 00 00 66 66 66 66 90 55 48 89 e5 41 57 41 89 f7 41 56 41 89 ce 41 55 41 89 d5 41 54 53 48 89 fb <4c> 8b 67 30 f0 41 ff 44 24 44 49 8d 7c 24 40 e8 0e 0a 2d e1 44
[   65.065225] RIP  [<ffffffffa037d6ee>] __nfs4_close+0x1e/0x160 [nfsv4]
[   65.067175]  RSP <ffff88007b907d10>
[   65.068570] CR2: 0000000000000030
[   65.070098] ---[ end trace 0d1fe4f5c7dd6f8b ]---

Cc: <stable@vger.kernel.org> #3.7+
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The current caching model calls for the security label to be set on
first lookup and/or on any subsequent label changes. There is no
need to do it as part of an open reclaim.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

nfs_parse_mount_options returns 0 on error, not -errno.
Reported-by: NKarel Zak <kzak@redhat.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Reported-by: NEric Doutreleau <edoutreleau@genoscope.cns.fr>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

As of commit 5d422301 we no longer zero the
state.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The spec states that the client should not resend requests because
the server will disconnect if it needs to drop an RPC request.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

In nfs4_proc_getlk(), when some error causes a retry of the call to
_nfs4_proc_getlk(), we can end up with Oopses of the form

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000134
 IP: [<ffffffff8165270e>] _raw_spin_lock+0xe/0x30
<snip>
 Call Trace:
  [<ffffffff812f287d>] _atomic_dec_and_lock+0x4d/0x70
  [<ffffffffa053c4f2>] nfs4_put_lock_state+0x32/0xb0 [nfsv4]
  [<ffffffffa053c585>] nfs4_fl_release_lock+0x15/0x20 [nfsv4]
  [<ffffffffa0522c06>] _nfs4_proc_getlk.isra.40+0x146/0x170 [nfsv4]
  [<ffffffffa052ad99>] nfs4_proc_lock+0x399/0x5a0 [nfsv4]

The problem is that we don't clear the request->fl_ops after the first
try and so when we retry, nfs4_set_lock_state() exits early without
setting the lock stateid.
Regression introduced by commit 70cc6487
(locks: make ->lock release private data before returning in GETLK case)
Reported-by: NWeston Andros Adamson <dros@netapp.com>
Reported-by: NJorge Mora <mora@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: <stable@vger.kernel.org> #2.6.22+

The previous patch introduces a compile warning by not assigning an initial
value to the "flavor" variable.  This could only be a problem if the server
returns a supported secflavor list of length zero, but it's better to
fix this before it's ever hit.
Signed-off-by: NAnna Schumaker <bjschuma@netapp.com>
Acked-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Call nfs4_lookup_root_sec for each flavor returned by SECINFO_NO_NAME until
one works.

One example of a situation this fixes:

 - server configured for krb5
 - server principal somehow gets deleted from KDC
 - server still thinking krb is good, sends krb5 as first entry in
    SECINFO_NO_NAME response
 - client tries krb5, but this fails without even sending an RPC because
    gssd's requests to the KDC can't find the server's principal
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

We need to ensure that the initialisation of the data server nfs_client
structure in nfs4_ds_connect is correctly ordered w.r.t. the read of
ds->ds_clp in nfs4_fl_prepare_ds.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

- Fix an Oops when nfs4_ds_connect() returns an error.
- Always check the device status after waiting for a connect to complete.
Reported-by: NAndy Adamson <andros@netapp.com>
Reported-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: <stable@vger.kernel.org> # v3.10+

Determine if we've created a new file by examining the directory change
attribute and/or the O_EXCL flag.

This fixes a regression when doing a non-exclusive create of a new file.
If the FILE_CREATED flag is not set, the atomic_open() command will
perform full file access permissions checks instead of just checking
for MAY_OPEN.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Set FILE_CREATED on O_CREAT|O_EXCL.  If the NFS server honored our request
for exclusivity then this must be correct.

Currently this is a no-op, since the VFS sets FILE_CREATED anyway.  The
next patch will, however, require this flag to be always set by
filesystems.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

truncate_pagecache() doesn't care about old size since commit
cedabed4 ("vfs: Fix vmtruncate() regression").  Let's drop it.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

No need to spam the logs
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The cl_machine_cred doesn't need to be reference counted here -
a reference is held is for the lifetime of the struct nfs_client.
Also, no need to put_rpccred the rpc_message.rpc_cred.
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Recent SP4_MACH_CRED changes allows rpc_message.rpc_cred to change,
so keep a separate pointer to the machine cred for put_rpccred.
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Request SP4_MACH_CRED WRITE and COMMIT support in spo_must_allow list --
they're already supported by the client.
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Convert the filesystem shrinkers to use the new API, and standardise some
of the behaviours of the shrinkers at the same time.  For example,
nr_to_scan means the number of objects to scan, not the number of objects
to free.

I refactored the CIFS idmap shrinker a little - it really needs to be
broken up into a shrinker per tree and keep an item count with the tree
root so that we don't need to walk the tree every time the shrinker needs
to count the number of objects in the tree (i.e.  all the time under
memory pressure).

[glommer@openvz.org: fixes for ext4, ubifs, nfs, cifs and glock. Fixes are needed mainly due to new code merged in the tree]
[assorted fixes folded in]
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NGlauber Costa <glommer@openvz.org>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Acked-by: NJan Kara <jack@suse.cz>
Acked-by: NSteven Whitehouse <swhiteho@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Rientjes <rientjes@google.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: J. Bruce Fields <bfields@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The sysctl knob sysctl_vfs_cache_pressure is used to determine which
percentage of the shrinkable objects in our cache we should actively try
to shrink.

It works great in situations in which we have many objects (at least more
than 100), because the aproximation errors will be negligible.  But if
this is not the case, specially when total_objects < 100, we may end up
concluding that we have no objects at all (total / 100 = 0, if total <
100).

This is certainly not the biggest killer in the world, but may matter in
very low kernel memory situations.
Signed-off-by: NGlauber Costa <glommer@openvz.org>
Reviewed-by: NCarlos Maiolino <cmaiolino@redhat.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Rientjes <rientjes@google.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: J. Bruce Fields <bfields@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The operation status is decoded in decode_op_hdr.

Stop the print_overflow message that is always hit without this patch:
nfs: decode_free_stateid: prematurely hit end of receive buffer. Remaining
buffer length is 0 words.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Commit 97431204 introduced a regression
that causes SECINFO_NO_NAME to fail without sending an RPC if:

 1) the nfs_client's rpc_client is using krb5i/p (now tried by default)
 2) the current user doesn't have valid kerberos credentials

This situation is quite common - as of now a sec=sys mount would use
krb5i for the nfs_client's rpc_client and a user would hardly be faulted
for not having run kinit.

The solution is to use the machine cred when trying to use an integrity
protected auth flavor for SECINFO_NO_NAME.

Older servers may not support using the machine cred or an integrity
protected auth flavor for SECINFO_NO_NAME in every circumstance, so we fall
back to using the user's cred and the filesystem's auth flavor in this case.

We run into another problem when running against linux nfs servers -
they return NFS4ERR_WRONGSEC when using integrity auth flavor (unless the
mount is also that flavor) even though that is not a valid error for
SECINFO*.  Even though it's against spec, handle WRONGSEC errors on
SECINFO_NO_NAME by falling back to using the user cred and the
filesystem's auth flavor.
Signed-off-by: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Also don't worry about obsolete mount flags...
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

In cases where the parent super block was not mounted with a 'sec=' line,
allow autonegotiation of security for the submounts.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Ensure that nfs4_proc_lookup_common respects the NFS_MOUNT_SECFLAVOUR
flag.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>