Andy Adamson reports:

The state manager is recovering expired state and recovery OPENs are being
processed. If kswapd is pruning inodes at the same time, a deadlock can occur
when kswapd calls evict_inode on an NFSv4.1 inode with a layout, and the
resultant layoutreturn gets an error that the state mangager is to handle,
causing the layoutreturn to wait on the (NFS client) cl_rpcwaitq.

At the same time an open is waiting for the inode deletion to complete in
__wait_on_freeing_inode.

If the open is either the open called by the state manager, or an open from
the same open owner that is holding the NFSv4 sequence id which causes the
OPEN from the state manager to wait for the sequence id on the Seqid_waitqueue,
then the state is deadlocked with kswapd.

The fix is simply to have layoutreturn ignore all errors except NFS4ERR_DELAY.
We already know that layouts are dropped on all server reboots, and that
it has to be coded to deal with the "forgetful client model" that doesn't
send layoutreturns.
Reported-by: Andy Adamson <andros@netapp.com>
Link: http://lkml.kernel.org/r/1385402270-14284-1-git-send-email-andros@netapp.comSigned-off-by: Trond Myklebust <Trond.Myklebust@primarydata.com>

Otherwise RPCSEC_GSS_DESTROY messages are not sent.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Also ensure that we zero out the stateid mode when exiting
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

If the DELEGRETURN errors out with something like NFS4ERR_BAD_STATEID
then there is no recovery possible. Just quit without returning an error.

Also, note that the client must not assume that the NFSv4 lease has been
renewed when it sees an error on DELEGRETURN.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org

When the state manager is processing the NFS4CLNT_DELEGRETURN flag, session
draining is off, but DELEGRETURN can still get a session error.
The async handler calls nfs4_schedule_session_recovery returns -EAGAIN, and
the DELEGRETURN done then restarts the RPC task in the prepare state.
With the state manager still processing the NFS4CLNT_DELEGRETURN flag with
session draining off, these DELEGRETURNs will cycle with errors filling up the
session slots.

This prevents OPEN reclaims (from nfs_delegation_claim_opens) required by the
NFS4CLNT_DELEGRETURN state manager processing from completing, hanging the
state manager in the __rpc_wait_for_completion_task in nfs4_run_open_task
as seen in this kernel thread dump:

kernel: 4.12.32.53-ma D 0000000000000000     0  3393      2 0x00000000
kernel: ffff88013995fb60 0000000000000046 ffff880138cc5400 ffff88013a9df140
kernel: ffff8800000265c0 ffffffff8116eef0 ffff88013fc10080 0000000300000001
kernel: ffff88013a4ad058 ffff88013995ffd8 000000000000fbc8 ffff88013a4ad058
kernel: Call Trace:
kernel: [<ffffffff8116eef0>] ? cache_alloc_refill+0x1c0/0x240
kernel: [<ffffffffa0358110>] ? rpc_wait_bit_killable+0x0/0xa0 [sunrpc]
kernel: [<ffffffffa0358152>] rpc_wait_bit_killable+0x42/0xa0 [sunrpc]
kernel: [<ffffffff8152914f>] __wait_on_bit+0x5f/0x90
kernel: [<ffffffffa0358110>] ? rpc_wait_bit_killable+0x0/0xa0 [sunrpc]
kernel: [<ffffffff815291f8>] out_of_line_wait_on_bit+0x78/0x90
kernel: [<ffffffff8109b520>] ? wake_bit_function+0x0/0x50
kernel: [<ffffffffa035810d>] __rpc_wait_for_completion_task+0x2d/0x30 [sunrpc]
kernel: [<ffffffffa040d44c>] nfs4_run_open_task+0x11c/0x160 [nfs]
kernel: [<ffffffffa04114e7>] nfs4_open_recover_helper+0x87/0x120 [nfs]
kernel: [<ffffffffa0411646>] nfs4_open_recover+0xc6/0x150 [nfs]
kernel: [<ffffffffa040cc6f>] ? nfs4_open_recoverdata_alloc+0x2f/0x60 [nfs]
kernel: [<ffffffffa0414e1a>] nfs4_open_delegation_recall+0x6a/0xa0 [nfs]
kernel: [<ffffffffa0424020>] nfs_end_delegation_return+0x120/0x2e0 [nfs]
kernel: [<ffffffff8109580f>] ? queue_work+0x1f/0x30
kernel: [<ffffffffa0424347>] nfs_client_return_marked_delegations+0xd7/0x110 [nfs]
kernel: [<ffffffffa04225d8>] nfs4_run_state_manager+0x548/0x620 [nfs]
kernel: [<ffffffffa0422090>] ? nfs4_run_state_manager+0x0/0x620 [nfs]
kernel: [<ffffffff8109b0f6>] kthread+0x96/0xa0
kernel: [<ffffffff8100c20a>] child_rip+0xa/0x20
kernel: [<ffffffff8109b060>] ? kthread+0x0/0xa0
kernel: [<ffffffff8100c200>] ? child_rip+0x0/0x20

The state manager can not therefore process the DELEGRETURN session errors.
Change the async handler to wait for recovery on session errors.
Signed-off-by: Andy Adamson <andros@netapp.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Fix the following warning:

linux-nfs/fs/nfs/inode.c:315:1: warning: ‘inline’ is not at
beginning of declaration [-Wold-style-declaration]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

When CONFIG_NFS_V4_2 is toggled nfsd and lockd will be recompiled,
instead of only the nfs client.  This patch moves a small amount of code
into the client directory to avoid unnecessary recompiles.
Signed-off-by: Anna Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Defaulting to m seem to prevent building the pnfs layout modules into the
kernel.  Default to the value of CONFIG_NFS_V4 make sure they are
built in for built-in NFSv4 support and modular for a modular NFSv4.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The current test on valid use of the "migration" mount option can never
report an error as it will only do so if
    mnt->version !=4 && mnt->minor_version != 0
(and some other condition), but if that test would succeed, then the previous
test has already gone-to  out_minorversion_mismatch.

So change the && to an || to get correct semantics.
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Currently, when we try to mount and get back NFS4ERR_CLID_IN_USE or
NFS4ERR_WRONGSEC, we create a new rpc_clnt and then try the call again.
There is no guarantee that doing so will work however, so we can end up
retrying the call in an infinite loop.

Worse yet, we create the new client using rpc_clone_client_set_auth,
which creates the new client as a child of the old one. Thus, we can end
up with a *very* long lineage of rpc_clnts. When we go to put all of the
references to them, we can end up with a long call chain that can smash
the stack as each rpc_free_client() call can recurse back into itself.

This patch fixes this by simply ensuring that the SETCLIENTID call will
only be retried in this situation if the last attempt did not use
RPC_AUTH_UNIX.

Note too that with this change, we don't need the (i > 2) check in the
-EACCES case since we now have a more reliable test as to whether we
should reattempt.

Cc: stable@vger.kernel.org # v3.10+
Cc: Chuck Lever <chuck.lever@oracle.com>
Tested-by/Acked-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

In cases where an rpc client has a parent hierarchy, then
rpc_free_client may end up calling rpc_release_client() on the
parent, thus recursing back into rpc_free_client. If the hierarchy
is deep enough, then we can get into situations where the stack
simply overflows.

The fix is to have rpc_release_client() loop so that it can take
care of the parent rpc client hierarchy without needing to
recurse.
Reported-by: Jeff Layton <jlayton@redhat.com>
Reported-by: Weston Andros Adamson <dros@netapp.com>
Reported-by: Bruce Fields <bfields@fieldses.org>
Link: http://lkml.kernel.org/r/2C73011F-0939-434C-9E4D-13A1EB1403D7@netapp.com
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The following scenario can cause silent data corruption when doing
NFS writes. It has mainly been observed when doing database writes
using O_DIRECT.

1) The RPC client uses sendpage() to do zero-copy of the page data.
2) Due to networking issues, the reply from the server is delayed,
   and so the RPC client times out.

3) The client issues a second sendpage of the page data as part of
   an RPC call retransmission.

4) The reply to the first transmission arrives from the server
   _before_ the client hardware has emptied the TCP socket send
   buffer.
5) After processing the reply, the RPC state machine rules that
   the call to be done, and triggers the completion callbacks.
6) The application notices the RPC call is done, and reuses the
   pages to store something else (e.g. a new write).

7) The client NIC drains the TCP socket send buffer. Since the
   page data has now changed, it reads a corrupted version of the
   initial RPC call, and puts it on the wire.

This patch fixes the problem in the following manner:

The ordering guarantees of TCP ensure that when the server sends a
reply, then we know that the _first_ transmission has completed. Using
zero-copy in that situation is therefore safe.
If a time out occurs, we then send the retransmission using sendmsg()
(i.e. no zero-copy), We then know that the socket contains a full copy of
the data, and so it will retransmit a faithful reproduction even if the
RPC call completes, and the application reuses the O_DIRECT buffer in
the meantime.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org

We already check for nfs_server_capable(inode, NFS_CAP_SECURITY_LABEL)
in nfs4_label_alloc()
We check the minor version in _nfs4_server_capabilities before setting
NFS_CAP_SECURITY_LABEL.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

We don't want to be setting capabilities and/or requesting attributes
that are not appropriate for the NFSv4 minor version.

- Ensure that we clear the NFS_CAP_SECURITY_LABEL capability when appropriate
- Ensure that we limit the attribute bitmasks to the mounted_on_fileid
  attribute and less for NFSv4.0
- Ensure that we limit the attribute bitmasks to suppattr_exclcreat and
  less for NFSv4.1
- Ensure that we limit it to change_sec_label or less for NFSv4.2
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Currently, if the server is doing NFSv4.2 and supports labeled NFS, then
our on-the-wire READDIR request ends up asking for the label information,
which is then ignored unless we're doing readdirplus.
This patch ensures that READDIR doesn't ask the server for label information
at all unless the readdir->bitmask contains the FATTR4_WORD2_SECURITY_LABEL
attribute, and the readdir->plus flag is set.

While we're at it, optimise away the 3rd bitmap field if it is zero.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Currently, we fetch the security label when revalidating an inode's
attributes, but don't apply it. This is in contrast to the readdir()
codepath where we do apply label changes.

Cc: Dave Quigley <dpquigl@davequigley.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

In the spec, the security label attribute id is '80', which means that
it should be bit number 80-64 == 16 in the 3rd word of the bitmap.

Fixes: 4488cc96: NFS: Add NFSv4.2 protocol constants
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: Steve Dickson <steved@redhat.com>
Cc: stable@vger.kernel.org # 3.11+
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Ensure that _nfs4_do_get_security_label() also initialises the
SEQUENCE call correctly, by having it call into nfs4_call_sync().
Reported-by: Jeff Layton <jlayton@redhat.com>
Cc: stable@vger.kernel.org # 3.11+
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Chao reported the following oops when testing labeled NFS:

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffffa0568703>] nfs4_xdr_enc_setattr+0x43/0x110 [nfsv4]
PGD 277bbd067 PUD 2777ea067 PMD 0
Oops: 0000 [#1] SMP
Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache sg coretemp kvm_intel kvm crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel lrw gf128mul iTCO_wdt glue_helper ablk_helper cryptd iTCO_vendor_support bnx2 pcspkr serio_raw i7core_edac cdc_ether microcode usbnet edac_core mii lpc_ich i2c_i801 mfd_core shpchp ioatdma dca acpi_cpufreq mperf nfsd auth_rpcgss nfs_acl lockd sunrpc xfs libcrc32c sr_mod sd_mod cdrom crc_t10dif mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper ata_generic ttm pata_acpi drm ata_piix libata megaraid_sas i2c_core dm_mirror dm_region_hash dm_log dm_mod
CPU: 4 PID: 25657 Comm: chcon Not tainted 3.10.0-33.el7.x86_64 #1
Hardware name: IBM System x3550 M3 -[7944OEJ]-/90Y4784     , BIOS -[D6E150CUS-1.11]- 02/08/2011
task: ffff880178397220 ti: ffff8801595d2000 task.ti: ffff8801595d2000
RIP: 0010:[<ffffffffa0568703>]  [<ffffffffa0568703>] nfs4_xdr_enc_setattr+0x43/0x110 [nfsv4]
RSP: 0018:ffff8801595d3888  EFLAGS: 00010296
RAX: 0000000000000000 RBX: ffff8801595d3b30 RCX: 0000000000000b4c
RDX: ffff8801595d3b30 RSI: ffff8801595d38e0 RDI: ffff880278b6ec00
RBP: ffff8801595d38c8 R08: ffff8801595d3b30 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801595d38e0
R13: ffff880277a4a780 R14: ffffffffa05686c0 R15: ffff8802765f206c
FS:  00007f2c68486800(0000) GS:ffff88027fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000027651a000 CR4: 00000000000007e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
 0000000000000000 0000000000000000 0000000000000000 0000000000000000
 0000000000000000 ffff880277865800 ffff880278b6ec00 ffff880277a4a780
 ffff8801595d3948 ffffffffa02ad926 ffff8801595d3b30 ffff8802765f206c
Call Trace:
 [<ffffffffa02ad926>] rpcauth_wrap_req+0x86/0xd0 [sunrpc]
 [<ffffffffa02a1d40>] ? call_connect+0xb0/0xb0 [sunrpc]
 [<ffffffffa02a1d40>] ? call_connect+0xb0/0xb0 [sunrpc]
 [<ffffffffa02a1ecb>] call_transmit+0x18b/0x290 [sunrpc]
 [<ffffffffa02a1d40>] ? call_connect+0xb0/0xb0 [sunrpc]
 [<ffffffffa02aae14>] __rpc_execute+0x84/0x400 [sunrpc]
 [<ffffffffa02ac40e>] rpc_execute+0x5e/0xa0 [sunrpc]
 [<ffffffffa02a2ea0>] rpc_run_task+0x70/0x90 [sunrpc]
 [<ffffffffa02a2f03>] rpc_call_sync+0x43/0xa0 [sunrpc]
 [<ffffffffa055284d>] _nfs4_do_set_security_label+0x11d/0x170 [nfsv4]
 [<ffffffffa0558861>] nfs4_set_security_label.isra.69+0xf1/0x1d0 [nfsv4]
 [<ffffffff815fca8b>] ? avc_alloc_node+0x24/0x125
 [<ffffffff815fcd2f>] ? avc_compute_av+0x1a3/0x1b5
 [<ffffffffa055897b>] nfs4_xattr_set_nfs4_label+0x3b/0x50 [nfsv4]
 [<ffffffff811bc772>] generic_setxattr+0x62/0x80
 [<ffffffff811bcfc3>] __vfs_setxattr_noperm+0x63/0x1b0
 [<ffffffff811bd1c5>] vfs_setxattr+0xb5/0xc0
 [<ffffffff811bd2fe>] setxattr+0x12e/0x1c0
 [<ffffffff811a4d22>] ? final_putname+0x22/0x50
 [<ffffffff811a4f2b>] ? putname+0x2b/0x40
 [<ffffffff811aa1cf>] ? user_path_at_empty+0x5f/0x90
 [<ffffffff8119bc29>] ? __sb_start_write+0x49/0x100
 [<ffffffff811bd66f>] SyS_lsetxattr+0x8f/0xd0
 [<ffffffff8160cf99>] system_call_fastpath+0x16/0x1b
Code: 48 8b 02 48 c7 45 c0 00 00 00 00 48 c7 45 c8 00 00 00 00 48 c7 45 d0 00 00 00 00 48 c7 45 d8 00 00 00 00 48 c7 45 e0 00 00 00 00 <48> 8b 00 48 8b 00 48 85 c0 0f 84 ae 00 00 00 48 8b 80 b8 03 00
RIP  [<ffffffffa0568703>] nfs4_xdr_enc_setattr+0x43/0x110 [nfsv4]
 RSP <ffff8801595d3888>
CR2: 0000000000000000

The problem is that _nfs4_do_set_security_label calls rpc_call_sync()
directly which fails to do any setup of the SEQUENCE call. Have it use
nfs4_call_sync() instead which does the right thing. While we're at it
change the name of "args" to "arg" to better match the pattern in
_nfs4_do_setattr.
Reported-by: Chao Ye <cye@redhat.com>
Cc: David Quigley <dpquigl@davequigley.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: stable@vger.kernel.org # 3.11+
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

commit 6686390b (NFS: remove incorrect "Lock reclaim failed!"
warning.) added a test for a delegation before checking to see if any
reclaimed locks failed. The test however is backward and is only doing
that check when a delegation is held instead of when one isn't.

Cc: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Fixes: 6686390b: NFS: remove incorrect "Lock reclaim failed!" warning.
Cc: stable@vger.kernel.org # 3.12
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

There is no longer any need for a separate xs_local_destroy() helper.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

We have one report of a crash in xs_tcp_setup_socket.
The call path to the crash is:

  xs_tcp_setup_socket -> inet_stream_connect -> lock_sock_nested.

The 'sock' passed to that last function is NULL.

The only way I can see this happening is a concurrent call to
xs_close:

  xs_close -> xs_reset_transport -> sock_release -> inet_release

inet_release sets:
   sock->sk = NULL;
inet_stream_connect calls
   lock_sock(sock->sk);
which gets NULL.

All calls to xs_close are protected by XPRT_LOCKED as are most
activations of the workqueue which runs xs_tcp_setup_socket.
The exception is xs_tcp_schedule_linger_timeout.

So presumably the timeout queued by the later fires exactly when some
other code runs xs_close().

To protect against this we can move the cancel_delayed_work_sync()
call from xs_destory() to xs_close().

As xs_close is never called from the worker scheduled on
->connect_worker, this can never deadlock.
Signed-off-by: NeilBrown <neilb@suse.de>
[Trond: Make it safe to call cancel_delayed_work_sync() on AF_LOCAL sockets]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Remove duplicated include.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Merge branch 'fscache' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into linux-next

Pull fs-cache fixes from David Howells:

Can you pull these commits to fix an issue with NFS whereby caching can be
enabled on a file that is open for writing by subsequently opening it for
reading.  This can be made to crash by opening it for writing again if you're
quick enough.

The gist of the patchset is that the cookie should be acquired at inode
creation only and subsequently enabled and disabled as appropriate (which
dispenses with the backing objects when they're not needed).

The extra synchronisation that NFS does can then be dispensed with as it is
thenceforth managed by FS-Cache.

Could you send these on to Linus?

This likely will need fixing also in CIFS and 9P also once the FS-Cache
changes are upstream.  AFS and Ceph are probably safe.

* 'fscache' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  NFS: Use i_writecount to control whether to get an fscache cookie in nfs_open()
  FS-Cache: Provide the ability to enable/disable cookies
  FS-Cache: Add use/unuse/wake cookie wrappers

This check was added by Al Viro with
d9e80b7d "nfs d_revalidate() is too
trigger-happy with d_drop()", with the explanation that we don't want to
remove the root of a disconnected tree, which will still be included on
the s_anon list.

But DCACHE_DISCONNECTED does *not* actually identify dentries that are
disconnected from the dentry tree or hashed on s_anon.  IS_ROOT() is the
way to do that.

Also add a comment from Al's commit to remind us why this check is
there.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

In gss_encode_v1_msg, it is pointless to BUG() after the overflow has
happened. Replace the existing sprintf()-based code with scnprintf(),
and warn if an overflow is ever triggered.

In gss_encode_v0_msg, replace the runtime BUG_ON() with an appropriate
compile-time BUILD_BUG_ON.
Reported-by: Bruce Fields <bfields@fieldses.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Add the missing 'break' to ensure that we don't corrupt a legacy 'v0' type
message by appending the 'v1'.

Cc: Bruce Fields <bfields@fieldses.org>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

If req allocated failed just goto out_free, no need to check the
'i < num_prealloc'. There is just code simplification, no
functional changes.
Signed-off-by: Wang Weidong <wangweidong1@huawei.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Use 'PTR_ERR_OR_ZERO()' rather than 'IS_ERR(...) ? PTR_ERR(...) : 0'.
Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Use 'PTR_ERR_OR_ZERO()' rather than 'IS_ERR(...) ? PTR_ERR(...) : 0'.
Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

the 'error' variable was been assigned twice in vain.
Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

rpc_clnt_set_transport should use rcu_derefence_protected(), as it is
only safe to be called with the rpc_clnt::cl_lock held.

Cc: Chuck Lever <Chuck.Lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

This patch adds support for multiple security options which can be
specified using a colon-delimited list of security flavors (the same
syntax as nfsd's exports file).

This is useful, for instance, when NFSv4.x mounts cross SECINFO
boundaries. With this patch a user can use "sec=krb5i,krb5p"
to mount a remote filesystem using krb5i, but can still cross
into krb5p-only exports.

New mounts will try all security options before failing.  NFSv4.x
SECINFO results will be compared against the sec= flavors to
find the first flavor in both lists or if no match is found will
return -EPERM.
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Since the parsed sec= flavor is now stored in nfs_server->auth_info,
we no longer need an nfs_server flag to determine if a sec= option was
used.

This flag has not been completely removed because it is still needed for
the (old but still supported) non-text parsed mount options ABI
compatability.
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Cache the auth_info structure in nfs_server and pass these values to submounts.

This lays the groundwork for supporting multiple sec= options.
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

When filling parsed_mount_data, store the parsed sec= mount option in
the new struct nfs_auth_info and the chosen flavor in selected_flavor.

This patch lays the groundwork for supporting multiple sec= options.
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

It's not used outside of nfs4namespace.c anymore.
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

In nfs4_wait_clnt_recover(), hold a reference to the clp being
waited on.  The state manager can reduce clp->cl_count to 1, in
which case the nfs_put_client() in nfs4_run_state_manager() can
free *clp before wait_on_bit() returns and allows
nfs4_wait_clnt_recover() to run again.

The behavior at that point is non-deterministic.  If the waited-on
bit still happens to be zero, wait_on_bit() will wake the waiter as
expected.  If the bit is set again (say, if the memory was poisoned
when freed) wait_on_bit() can leave the waiter asleep.

This is a narrow fix which ensures the safety of accessing *clp in
nfs4_wait_clnt_recover(), but does not address the continued use
of a possibly freed *clp after nfs4_wait_clnt_recover() returns
(see nfs_end_delegation_return(), for example).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Broadly speaking, v4.1 migration is untested.  There are no servers
in the wild that support NFSv4.1 migration.  However, as server
implementations become available, we do want to enable testing by
developers, while leaving it disabled for environments for which
broken migration support would be an unpleasant surprise.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>