Commit Graph

220 Commits

Author SHA1 Message Date
Andy Adamson f9c96fcc50 NFSv4.1 free slot before resending I/O to MDS
Fix a dynamic session slot leak where a slot is preallocated and I/O is
resent through the MDS.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-01-29 11:54:55 -05:00
Anna Schumaker 694e096fd7 NFS: Enabling v4.2 should not recompile nfsd and lockd
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>
2013-11-19 16:20:40 -05:00
Weston Andros Adamson 47fd88e6b7 NFSv4: make nfs_find_best_sec static
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>
2013-10-28 15:33:34 -04:00
Chuck Lever b7f7a66e42 NFS: Support NFS4ERR_LEASE_MOVED recovery in state manager
A migration on the FSID in play for the current NFS operation
is reported via the error status code NFS4ERR_MOVED.

"Lease moved" means that a migration has occurred on some other
FSID than the one for the current operation.  It's a signal that
the client should take action immediately to handle a migration
that it may not have noticed otherwise.  This is so that the
client's lease does not expire unnoticed on the destination server.

In NFSv4.0, a moved lease is reported with the NFS4ERR_LEASE_MOVED
error status code.

To recover from NFS4ERR_LEASE_MOVED, check each FSID for that server
to see if it is still present.  Invoke nfs4_try_migration() if the
FSID is no longer present on the server.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-10-28 15:30:21 -04:00
Chuck Lever 44c9993384 NFS: Add method to detect whether an FSID is still on the server
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: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-10-28 15:30:03 -04:00
Chuck Lever c9fdeb280b NFS: Add basic migration support to state manager thread
Migration recovery and state recovery must be serialized, so handle
both in the state manager thread.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-10-28 15:24:40 -04:00
Chuck Lever b03d735b4c NFS: Add method to retrieve fs_locations during migration recovery
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: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-10-28 15:24:00 -04:00
Chuck Lever ec011fe847 NFS: Introduce a vector of migration recovery ops
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: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-10-28 15:23:17 -04:00
Chuck Lever 800c06a5bf NFS: Add functions to swap transports during migration recovery
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: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-10-28 15:23:07 -04:00
Weston Andros Adamson 312cd958a7 NFSv4.1: sp4_mach_cred: WARN_ON -> WARN_ON_ONCE
No need to spam the logs

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-11 09:08:08 -04:00
Weston Andros Adamson ade33ff58e NFSv4.1: sp4_mach_cred: no need to ref count creds
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: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-11 09:07:53 -04:00
Trond Myklebust 5e6b19901b NFSv4: Fix security auto-negotiation
NFSv4 security auto-negotiation has been broken since
commit 4580a92d44 (NFS:
Use server-recommended security flavor by default (NFSv3))
because nfs4_try_mount() will automatically select AUTH_SYS
if it sees no auth flavours.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
2013-09-07 16:18:30 -04:00
Weston Andros Adamson 8c21c62c44 nfs4.1: Add SP4_MACH_CRED write and commit support
WRITE and COMMIT can use the machine credential.

If WRITE is supported and COMMIT is not, make all (mach cred) writes FILE_SYNC4.

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-05 10:50:45 -04:00
Weston Andros Adamson ab4c236135 nfs4.1: Add state protection handler
Add nfs4_state_protect - the function responsible for switching to the machine
credential and the correct rpc client when SP4_MACH_CRED is in use.

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-05 10:43:33 -04:00
Trond Myklebust f6de7a39c1 NFSv4: Document the recover_lost_locks kernel parameter
Rename the new 'recover_locks' kernel parameter to 'recover_lost_locks'
and change the default to 'false'. Document why in
Documentation/kernel-parameters.txt

Move the 'recover_lost_locks' kernel parameter to fs/nfs/super.c to
make it easy to backport to kernels prior to 3.6.x, which don't have
a separate NFSv4 module.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-04 12:26:32 -04:00
NeilBrown ef1820f9be NFSv4: Don't try to recover NFSv4 locks when they are lost.
When an NFSv4 client loses contact with the server it can lose any
locks that it holds.

Currently when it reconnects to the server it simply tries to reclaim
those locks.  This might succeed even though some other client has
held and released a lock in the mean time.  So the first client might
think the file is unchanged, but it isn't.  This isn't good.

If, when recovery happens, the locks cannot be claimed because some
other client still holds the lock, then we get a message in the kernel
logs, but the client can still write.  So two clients can both think
they have a lock and can both write at the same time.  This is equally
not good.

There was a patch a while ago
  http://comments.gmane.org/gmane.linux.nfs/41917

which tried to address some of this, but it didn't seem to go
anywhere.  That patch would also send a signal to the process.  That
might be useful but for now this patch just causes writes to fail.

For NFSv4 (unlike v2/v3) there is a strong link between the lock and
the write request so we can fairly easily fail any IO of the lock is
gone.  While some applications might not expect this, it is still
safer than allowing the write to succeed.

Because this is a fairly big change in behaviour a module parameter,
"recover_locks", is introduced which defaults to true (the current
behaviour) but can be set to "false" to tell the client not to try to
recover things that were lost.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-04 12:26:32 -04:00
Chuck Lever abf79bb341 NFS: Add a slot table to struct nfs_client for NFSv4.0 transport blocking
Anchor an nfs4_slot_table in the nfs_client for use with NFSv4.0
transport blocking.  It is initialized only for NFSv4.0 nfs_client's.

Introduce appropriate minor version ops to handle nfs_client
initialization and shutdown requirements that differ for each minor
version.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-03 15:26:35 -04:00
Chuck Lever 220e09ccd3 NFS: Remove unused call_sync minor version op
Clean up.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-03 15:26:33 -04:00
Chuck Lever 9915ea7e0a NFS: Add RPC callouts to start NFSv4.0 synchronous requests
Refactor nfs4_call_sync_sequence() so it is used for NFSv4.0 now.
The RPC callouts will house transport blocking logic similar to
NFSv4.1 sessions.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-03 15:26:32 -04:00
Chuck Lever 5a580e0ae2 NFS: Clean up nfs4_setup_sequence()
Clean up: Both the NFSv4.0 and NFSv4.1 version of
nfs4_setup_sequence() are used only in fs/nfs/nfs4proc.c.  No need
to keep global header declarations for either version.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-09-03 15:26:31 -04:00
Chuck Lever 73d8bde5e4 NFS: Never use user credentials for lease renewal
Never try to use a non-UID 0 user credential for lease management,
as that credential can change out from under us.  The server will
block NFSv4 lease recovery with NFS4ERR_CLID_INUSE.

Since the mechanism to acquire a credential for lease management
is now the same for all minor versions, replace the minor version-
specific callout with a single function.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-08-07 13:06:08 -04:00
Trond Myklebust 959d921f5e Merge branch 'labeled-nfs' into linux-next
* labeled-nfs:
  NFS: Apply v4.1 capabilities to v4.2
  NFS: Add in v4.2 callback operation
  NFS: Make callbacks minor version generic
  Kconfig: Add Kconfig entry for Labeled NFS V4 client
  NFS: Extend NFS xattr handlers to accept the security namespace
  NFS: Client implementation of Labeled-NFS
  NFS: Add label lifecycle management
  NFS:Add labels to client function prototypes
  NFSv4: Extend fattr bitmaps to support all 3 words
  NFSv4: Introduce new label structure
  NFSv4: Add label recommended attribute and NFSv4 flags
  NFSv4.2: Added NFS v4.2 support to the NFS client
  SELinux: Add new labeling type native labels
  LSM: Add flags field to security_sb_set_mnt_opts for in kernel mount data.
  Security: Add Hook to test if the particular xattr is part of a MAC model.
  Security: Add hook to calculate context based on a negative dentry.
  NFS: Add NFSv4.2 protocol constants

Conflicts:
	fs/nfs/nfs4proc.c
2013-06-28 16:29:51 -04:00
David Quigley a09df2ca23 NFSv4: Extend fattr bitmaps to support all 3 words
The fattr handling bitmap code only uses the first two fattr words sofar. This
patch adds the 3rd word to being sent but doesn't populate it yet.

Signed-off-by: Miguel Rodel Felipe <Rodel_FM@dsi.a-star.edu.sg>
Signed-off-by: Phua Eu Gene <PHUA_Eu_Gene@dsi.a-star.edu.sg>
Signed-off-by: Khin Mi Mi Aung <Mi_Mi_AUNG@dsi.a-star.edu.sg>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-06-08 16:20:14 -04:00
Trond Myklebust 965e9c23de NFSv4.1: Ensure that reclaim_complete uses the right credential
We want to use the same credential for reclaim_complete as we used
for the exchange_id call.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-06-06 16:24:35 -04:00
Trond Myklebust c8b2d0bfd3 NFSv4.1: Ensure that we free the lock stateid on the server
This ensures that the server doesn't need to keep huge numbers of
lock stateids waiting around for the final CLOSE.
See section 8.2.4 in RFC5661.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-05-06 17:24:27 -04:00
Trond Myklebust 92b40e9384 NFSv4: Use the open stateid if the delegation has the wrong mode
Fix nfs4_select_rw_stateid() so that it chooses the open stateid
(or an all-zero stateid) if the delegation does not match the selected
read/write mode.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-04-20 01:39:42 -04:00
Trond Myklebust 39c6daae70 NFSv4: Prepare for minorversion-specific nfs_server capabilities
Clean up the setting of the nfs_server->caps, by shoving it all
into nfs4_server_common_setup().
Then add an 'initial capabilities' field into struct nfs4_minor_version_ops.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-03-25 12:04:11 -04:00
Trond Myklebust 5521abfdcf NFSv4: Resend the READ/WRITE RPC call if a stateid change causes an error
Adds logic to ensure that if the server returns a BAD_STATEID,
or other state related error, then we check if the stateid has
already changed. If it has, then rather than start state recovery,
we should just resend the failed RPC call with the new stateid.

Allow nfs4_select_rw_stateid to notify that the stateid is unstable by
having it return -EWOULDBLOCK if an RPC is underway that might change the
stateid.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-03-25 12:04:10 -04:00
Trond Myklebust 9b20614988 NFSv4: The stateid must remain the same for replayed RPC calls
If we replay a READ or WRITE call, we should not be changing the
stateid. Currently, we may end up doing so, because the stateid
is only selected at xdr encode time.

This patch ensures that we select the stateid after we get an NFSv4.1
session slot, and that we keep that same stateid across retries.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-03-25 12:04:10 -04:00
Trond Myklebust 5d422301f9 NFSv4: Fail I/O if the state recovery fails irrevocably
If state recovery fails with an ESTALE or a ENOENT, then we shouldn't
keep retrying. Instead, mark the stateid as being invalid and
fail the I/O with an EIO error.
For other operations such as POSIX and BSD file locking, truncate
etc, fail with an EBADF to indicate that this file descriptor is no
longer valid.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-03-25 12:04:10 -04:00
Trond Myklebust 65b62a29f7 NFSv4: Ensure delegation recall and byte range lock removal don't conflict
Add a mutex to the struct nfs4_state_owner to ensure that delegation
recall doesn't conflict with byte range lock removal.

Note that we nest the new mutex _outside_ the state manager reclaim
protection (nfsi->rwsem) in order to avoid deadlocks.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-02-11 15:33:13 -05:00
Trond Myklebust c137afabe3 NFSv4: Allow the state manager to mark an open_owner as being recovered
This patch adds a seqcount_t lock for use by the state manager to
signal that an open owner has been recovered. This mechanism will be
used by the delegation, open and byte range lock code in order to
figure out if they need to replay requests due to collisions with
lock recovery.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-02-11 15:33:11 -05:00
Trond Myklebust 7ce0171d4f Merge branch 'bugfixes' into nfs-for-next 2012-12-11 09:16:26 -05:00
Trond Myklebust 275e7e20aa NFSv4.1: Remove the 'FIFO' behaviour for nfs41_setup_sequence
It is more important to preserve the task priority behaviour, which ensures
that things like reclaim writes take precedence over background and kupdate
writes.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:50 +01:00
Trond Myklebust fd0c09537a NFSv4: Simplify the NFSv4/v4.1 synchronous call switch
We shouldn't need to pass the 'cache_reply' parameter if we
initialise the sequence_args/sequence_res in the caller.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:49 +01:00
Trond Myklebust d9afbd1b08 NFSv4.1: Simplify the sequence setup
Nobody calls nfs4_setup_sequence or nfs41_setup_sequence without
also calling rpc_call_start() on success. This commit therefore
folds the rpc_call_start call into nfs41_setup_sequence().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:48 +01:00
Trond Myklebust c10e449827 NFSv4.1: Ping server when our session table limits are too high
If the server requests a lower target_highest_slotid, then ensure
that we ping it with at least one RPC call containing an
appropriate SEQUENCE op. This ensures that the server won't need to
send a recall callback in order to shrink the slot table.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:47 +01:00
Trond Myklebust 76e697ba7e NFSv4.1: Move slot table and session struct definitions to nfs4session.h
Clean up. Gather NFSv4.1 slot definitions in fs/nfs/nfs4session.h.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:46 +01:00
Trond Myklebust 73e39aaa83 NFSv4.1: Cleanup move session slot management to fs/nfs/nfs4session.c
NFSv4.1 session management is getting complex enough to deserve
a separate file.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:45 +01:00
Trond Myklebust 3302127967 NFSv4: Move nfs4_wait_clnt_recover and nfs4_client_recover_expired_lease
nfs4_wait_clnt_recover and nfs4_client_recover_expired_lease are both
generic state related functions. As such, they belong in nfs4state.c,
and not nfs4proc.c

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:45 +01:00
Trond Myklebust 5d63360dd8 NFSv4.1: Clean up session draining
Coalesce nfs4_check_drain_bc_complete and nfs4_check_drain_fc_complete
into a single function that can be called when the slot table is known
to be empty, then change nfs4_callback_free_slot() and nfs4_free_slot()
to use it.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:44 +01:00
Trond Myklebust ac0748359a NFSv4.1: CB_RECALL_SLOT must schedule a sequence op after updating targets
RFC5661 requires us to make sure that the server knows we've updated
our slot table size by sending at least one SEQUENCE op containing the
new 'highest_slotid' value.
We can do so using the 'CHECK_LEASE' functionality of the state
manager.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:43 +01:00
Trond Myklebust afa296103e NFSv4.1: Remove the state manager code to resize the slot table
The state manager no longer needs any special machinery to stop the
session flow and resize the slot table. It is all done on the fly by
the SEQUENCE op code now.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:43 +01:00
Trond Myklebust 87dda67e73 NFSv4.1: Allow SEQUENCE to resize the slot table on the fly
Instead of an array of slots, use a singly linked list of slots that
can be dynamically appended to or shrunk.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:42 +01:00
Trond Myklebust ce008c4bb9 NFSv4.1: Fix nfs4_callback_recallslot to work with dynamic slot allocation
Ensure that the NFSv4.1 CB_RECALL_SLOT callback updates the slot table
target max slotid safely.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06 00:30:37 +01:00
Trond Myklebust e3725ec015 NFSv4.1: Shrink struct nfs4_sequence_res by moving the session pointer
Move the session pointer into the slot table, then have struct nfs4_slot
point to that slot table.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-11-26 17:49:04 -05:00
Trond Myklebust fe20d7d5ee NFSv4: Fix a compile time warning when #undef CONFIG_NFS_V4_1
The function nfs4_get_machine_cred_locked is used by NFSv4.0 routines
too.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-11-21 22:59:28 -05:00
Trond Myklebust 9216106a84 NFSv4.1: clean up nfs4_recall_slot to use nfs4_alloc_slots
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-11-21 09:29:53 -05:00
Chuck Lever 6f2ea7f2a3 NFS: Add nfs4_unique_id boot parameter
An optional boot parameter is introduced to allow client
administrators to specify a string that the Linux NFS client can
insert into its nfs_client_id4 id string, to make it both more
globally unique, and to ensure that it doesn't change even if the
client's nodename changes.

If this boot parameter is not specified, the client's nodename is
used, as before.

Client installation procedures can create a unique string (typically,
a UUID) which remains unchanged during the lifetime of that client
instance.  This works just like creating a UUID for the label of the
system's root and boot volumes.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-10-01 15:33:33 -07:00
Chuck Lever 05f4c350ee NFS: Discover NFSv4 server trunking when mounting
"Server trunking" is a fancy named for a multi-homed NFS server.
Trunking might occur if a client sends NFS requests for a single
workload to multiple network interfaces on the same server.  There
are some implications for NFSv4 state management that make it useful
for a client to know if a single NFSv4 server instance is
multi-homed.  (Note this is only a consideration for NFSv4, not for
legacy versions of NFS, which are stateless).

If a client cares about server trunking, no NFSv4 operations can
proceed until that client determines who it is talking to.  Thus
server IP trunking discovery must be done when the client first
encounters an unfamiliar server IP address.

The nfs_get_client() function walks the nfs_client_list and matches
on server IP address.  The outcome of that walk tells us immediately
if we have an unfamiliar server IP address.  It invokes
nfs_init_client() in this case.  Thus, nfs4_init_client() is a good
spot to perform trunking discovery.

Discovery requires a client to establish a fresh client ID, so our
client will now send SETCLIENTID or EXCHANGE_ID as the first NFS
operation after a successful ping, rather than waiting for an
application to perform an operation that requires NFSv4 state.

The exact process for detecting trunking is different for NFSv4.0 and
NFSv4.1, so a minorversion-specific init_client callout method is
introduced.

CLID_INUSE recovery is important for the trunking discovery process.
CLID_INUSE is a sign the server recognizes the client's nfs_client_id4
id string, but the client is using the wrong principal this time for
the SETCLIENTID operation.  The SETCLIENTID must be retried with a
series of different principals until one works, and then the rest of
trunking discovery can proceed.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-10-01 15:33:33 -07:00