Xiaolong Ye's kernel test robot detected the following Oops:
[  299.158991] BUG: scheduling while atomic: mount.nfs/9387/0x00000002
[  299.169587] 2 locks held by mount.nfs/9387:
[  299.176165]  #0:  (nfs_clid_init_mutex){......}, at: [<ffffffff8130cc92>] nfs4_discover_server_trunking+0x47/0x1fc
[  299.201802]  #1:  (&(&nn->nfs_client_lock)->rlock){......}, at: [<ffffffff813125fa>] nfs40_walk_client_list+0x2e9/0x338
[  299.221979] CPU: 0 PID: 9387 Comm: mount.nfs Not tainted 4.11.0-rc7-00021-g14d1bbb0 #45
[  299.235584] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014
[  299.251176] Call Trace:
[  299.255192]  dump_stack+0x61/0x7e
[  299.260416]  __schedule_bug+0x65/0x74
[  299.266208]  __schedule+0x5d/0x87c
[  299.271883]  schedule+0x89/0x9a
[  299.276937]  schedule_timeout+0x232/0x289
[  299.283223]  ? detach_if_pending+0x10b/0x10b
[  299.289935]  schedule_timeout_uninterruptible+0x2a/0x2c
[  299.298266]  ? put_rpccred+0x3e/0x115
[  299.304327]  ? schedule_timeout_uninterruptible+0x2a/0x2c
[  299.312851]  msleep+0x1e/0x22
[  299.317612]  nfs4_discover_server_trunking+0x102/0x1fc
[  299.325644]  nfs4_init_client+0x13f/0x194

It looks as if we recently added a spin_lock() leak to
nfs40_walk_client_list() when cleaning up the code.
Reported-by: Nkernel test robot <xiaolong.ye@intel.com>
Fixes: 14d1bbb0 ("NFS: Create a common nfs4_match_client() function")
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If we cut out the dprintk()s, then we can return error codes directly
and cut out the goto.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

This puts all the common code in a single place for the
walk_client_list() functions.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Once again, we can remove the function and compare integer values
directly.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If we cut out the dprintk()s, then we don't even need this to be a
separate function.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Currently client doesn't respect max sizes server returns in CREATE_SESSION.
nfs4_session_set_rwsize() gets called and server->rsize, server->wsize are 0
so they never get set to the sizes returned by the server.
Signed-off-by: NOlga Kornievskaia <kolga@netapp.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

This parameter hasn't been used since f8407299 (Linux 3.11-rc2), so
let's remove it from this function and callers.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

It's possible that two different servers can return the same (clientid,
verifier) pair purely by coincidence.  Both are 64-bit values, but
depending on the server implementation, they can be highly predictable
and collisions may be quite likely, especially when there are lots of
servers.

So, check for this case.  If the clientid and verifier both match, then
we actually know they *can't* be the same server, since a new
SETCLIENTID to an already-known server should have changed the verifier.

This helps fix a bug that could cause the client to mount a filesystem
from the wrong server.
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Tested-by: NYongcheng Yang <yoyang@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Add a waitqueue head to the client structure. Have clients set a wait
on that queue prior to requesting a lock from the server. If the lock
is blocked, then we can use that to wait for wakeups.

Note that we do need to do this "manually" since we need to set the
wait on the waitqueue prior to requesting the lock, but requesting a
lock can involve activities that can block.

However, only do that for NFSv4.1 locks, either by compiling out
all of the waitqueue handling when CONFIG_NFS_V4_1 is disabled, or
skipping all of it at runtime if we're dealing with v4.0, or v4.1
servers that don't send lock callbacks.

Note too that even when we expect to get a lock callback, RFC5661
section 20.11.4 is pretty clear that we still need to poll for them,
so we do still sleep on a timeout. We do however always poll at the
longest interval in that case.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
[Anna: nfs4_retry_setlk() "status" should default to -ERESTARTSYS]
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Use an async exchange id call to test for session trunking

To conform with RFC 5661 section 18.35.4, the Non-Update on
Existing Clientid case, save the exchange id verifier in
cl_confirm and use it for the session trunking exhange id test.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

For session trunking, to compare nfs41_exchange_id_res with
existing nfs_client
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

For session trunking, to compare nfs41_exchange_id_res with
exiting nfs_client.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

If a server returns itself as a location while migrating, the client may
end up getting stuck attempting to migrate twice to the same server.  Catch
this by checking if the nfs_client found is the same as the existing
client.  For the other two callers to nfs4_set_client, the nfs_client will
always be ERR_PTR(-EINVAL).
Signed-off-by: NBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

result:

$ mount -o vers=4.1 dcache-lab007:/ /pnfs
$ cp /etc/profile /pnfs
tcp        0      0 131.169.185.68:1005     131.169.191.141:32049   ESTABLISHED
tcp        0      0 131.169.185.68:751      131.169.191.144:2049    ESTABLISHED
$

$ mount -o vers=4.1,noresvport dcache-lab007:/ /pnfs
$ cp /etc/profile /pnfs
tcp        0      0 131.169.185.68:34894    131.169.191.141:32049   ESTABLISHED
tcp        0      0 131.169.185.68:35722    131.169.191.144:2049    ESTABLISHED
$
Signed-off-by: NTigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Chris Worley reports:
 RIP: 0010:[<ffffffffa0245f80>]  [<ffffffffa0245f80>] rpc_new_client+0x2a0/0x2e0 [sunrpc]
 RSP: 0018:ffff880158f6f548  EFLAGS: 00010246
 RAX: 0000000000000000 RBX: ffff880234f8bc00 RCX: 000000000000ea60
 RDX: 0000000000074cc0 RSI: 000000000000ea60 RDI: ffff880234f8bcf0
 RBP: ffff880158f6f588 R08: 000000000001ac80 R09: ffff880237003300
 R10: ffff880201171000 R11: ffffea0000d75200 R12: ffffffffa03afc60
 R13: ffff880230c18800 R14: 0000000000000000 R15: ffff880158f6f680
 FS:  00007f0e32673740(0000) GS:ffff88023fc40000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
 CR2: 0000000000000008 CR3: 0000000234886000 CR4: 00000000001406e0
 Stack:
  ffffffffa047a680 0000000000000000 ffff880158f6f598 ffff880158f6f680
  ffff880158f6f680 ffff880234d11d00 ffff88023357f800 ffff880158f6f7d0
  ffff880158f6f5b8 ffffffffa024660a ffff880158f6f5b8 ffffffffa02492ec
 Call Trace:
  [<ffffffffa024660a>] rpc_create_xprt+0x1a/0xb0 [sunrpc]
  [<ffffffffa02492ec>] ? xprt_create_transport+0x13c/0x240 [sunrpc]
  [<ffffffffa0246766>] rpc_create+0xc6/0x1a0 [sunrpc]
  [<ffffffffa038e695>] nfs_create_rpc_client+0xf5/0x140 [nfs]
  [<ffffffffa038f31a>] nfs_init_client+0x3a/0xd0 [nfs]
  [<ffffffffa038f22f>] nfs_get_client+0x25f/0x310 [nfs]
  [<ffffffffa025cef8>] ? rpc_ntop+0xe8/0x100 [sunrpc]
  [<ffffffffa047512c>] nfs3_set_ds_client+0xcc/0x100 [nfsv3]
  [<ffffffffa041fa10>] nfs4_pnfs_ds_connect+0x120/0x400 [nfsv4]
  [<ffffffffa03d41c7>] nfs4_ff_layout_prepare_ds+0xe7/0x330 [nfs_layout_flexfiles]
  [<ffffffffa03d1b1b>] ff_layout_pg_init_write+0xcb/0x280 [nfs_layout_flexfiles]
  [<ffffffffa03a14dc>] __nfs_pageio_add_request+0x12c/0x490 [nfs]
  [<ffffffffa03a1fa2>] nfs_pageio_add_request+0xc2/0x2a0 [nfs]
  [<ffffffffa03a0365>] ? nfs_pageio_init+0x75/0x120 [nfs]
  [<ffffffffa03a5b50>] nfs_do_writepage+0x120/0x270 [nfs]
  [<ffffffffa03a5d31>] nfs_writepage_locked+0x61/0xc0 [nfs]
  [<ffffffff813d4115>] ? __percpu_counter_add+0x55/0x70
  [<ffffffffa03a6a9f>] nfs_wb_single_page+0xef/0x1c0 [nfs]
  [<ffffffff811ca4a3>] ? __dec_zone_page_state+0x33/0x40
  [<ffffffffa0395b21>] nfs_launder_page+0x41/0x90 [nfs]
  [<ffffffff811baba0>] invalidate_inode_pages2_range+0x340/0x3a0
  [<ffffffff811bac17>] invalidate_inode_pages2+0x17/0x20
  [<ffffffffa039960e>] nfs_release+0x9e/0xb0 [nfs]
  [<ffffffffa0399570>] ? nfs_open+0x60/0x60 [nfs]
  [<ffffffffa0394dad>] nfs_file_release+0x3d/0x60 [nfs]
  [<ffffffff81226e6c>] __fput+0xdc/0x1e0
  [<ffffffff81226fbe>] ____fput+0xe/0x10
  [<ffffffff810bf2e4>] task_work_run+0xc4/0xe0
  [<ffffffff810a4188>] do_exit+0x2e8/0xb30
  [<ffffffff8102471c>] ? do_audit_syscall_entry+0x6c/0x70
  [<ffffffff811464e6>] ? __audit_syscall_exit+0x1e6/0x280
  [<ffffffff810a4a5f>] do_group_exit+0x3f/0xa0
  [<ffffffff810a4ad4>] SyS_exit_group+0x14/0x20
  [<ffffffff8179b76e>] system_call_fastpath+0x12/0x71

Which seems to be due to a call to utsname() when in a task exit context
in order to determine the hostname to set in rpc_new_client().

In reality, what we want here is not the hostname of the current task, but
the hostname that was used to set up the metadata server.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If clp->cl_cb_ident is zero, then nfs_cb_idr_remove_locked() skips removing
it when the nfs_client is freed.  A decoding or server bug can then find
and try to put that first nfs_client which would lead to a crash.
Signed-off-by: NBenjamin Coddington <bcodding@redhat.com>
Fixes: d6870312 ("nfs4client: convert to idr_alloc()")
Cc: stable@vger.kernel.org
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

They already exist and do the exact same thing.  Let's save ourselves
several lines of code!
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Commit 7b1f1fd1 "NFSv4/4.1: Fix bugs in nfs4[01]_walk_client_list"
have change the logical of the list_for_each_entry().
Signed-off-by: NKinglong Mee <kinglongmee@gmail.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

This file is only used internally to the NFS v4 module, so it doesn't
need to be in the global include path.  I also renamed it from
nfs_idmap.h to nfs4idmap.h to emphasize that it's an NFSv4-only include
file.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

that's the bulk of filesystem drivers dealing with inodes of their own
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We do not want to allow a race with another NFS mount to cause
nfs41_walk_client_list() to establish a lease on our nfs_client before
we're done checking for trunking.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

flexfile layout may need to set such when making DS connections.
Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Signed-off-by: NTom Haynes <Thomas.Haynes@primarydata.com>

flexfile layout may use different auth flavor as specified by MDS.
Reviewed-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Signed-off-by: NTom Haynes <Thomas.Haynes@primarydata.com>

If we start state recovery on a client that failed to initialise correctly,
then we are very likely to Oops.
Reported-by: N"Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>
Link: http://lkml.kernel.org/r/130621862.279655.1421851650684.JavaMail.zimbra@desy.de
Cc: stable@vger.kernel.org
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Detect server trunking across transport protocols. Otherwise, an
RDMA mount and a TCP mount of the same server will end up with
separate nfs_clients using the same clientid4.
Reported-by: NDai Ngo <dai.ngo@oracle.com>
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

While we normally expect the NFSv4 client to always send the same client
owner to all servers, there are a couple of situations where that is not
the case:
 1) In NFSv4.0, switching between use of '-omigration' and not will cause
    the kernel to switch between using the non-uniform and uniform client
    strings.
 2) In NFSv4.1, or NFSv4.0 when using uniform client strings, if the
    uniquifier string is suddenly changed.

This patch will catch those situations by checking the client owner id
in the trunking detection code, and will do the right thing if it notices
that the strings differ.

Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Ensure that we cache the NFSv4/v4.1 client owner_id so that we can
verify it when we're doing trunking detection.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Currently, our trunking code will check for session trunking, but will
fail to detect client id trunking. This is a problem, because it means
that the client will fail to recognise that the two connections represent
shared state, even if they do not permit a shared session.
By removing the check for the server minor id, and only checking the
major id, we will end up doing the right thing in both cases: we close
down the new nfs_client and fall back to using the existing one.

Fixes: 05f4c350 ("NFS: Discover NFSv4 server trunking when mounting")
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org # 3.7.x
Tested-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

nfs4_init_callback() is never invoked for NFS versions other than 4.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

The nfs_put_client() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

There is a race between nfs4_state_manager() and
nfs_server_remove_lists() that happens during a nfsv3 mount.

The v3 mount notices there is already a supper block so
nfs_server_remove_lists() called which uses the nfs_client_lock
spin lock to synchronize access to the client list.

At the same time nfs4_state_manager() is running through
the client list looking for work to do, using the same
lock. When nfs4_state_manager() wins the race to the
list, a v3 client pointer is found and not ignored
properly which causes the panic.

Moving some protocol checks before the state checking
avoids the panic.

CC: Stable Tree <stable@vger.kernel.org>
Signed-off-by: NSteve Dickson <steved@redhat.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

We reference cl_hostname in many places for debugging purpose.
So make it useful by setting hostname when calling nfs_get_client.
Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If a timeout or a signal interrupts the NFSv4 trunking discovery
SETCLIENTID_CONFIRM call, then we don't know whether or not the
server has changed the callback identifier on us.
Assume that it did, and schedule a 'path down' recovery...
Tested-by: NSteve Dickson <steved@redhat.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

We need to use the same net namespace that was used to resolve
the hostname and sockaddr arguments.

Fixes: 32e62b7c (NFS: Add nfs4_update_server)
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

There may still be timers active on the session waitqueues. Make sure
that we kill them before freeing the memory.

Cc: stable@vger.kernel.org # 3.12+
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>