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

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>

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>

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>

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>

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>

NFSv4 security auto-negotiation has been broken since
commit 4580a92d (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: NTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>

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: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NWeston Andros Adamson <dros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NNeilBrown <neilb@suse.de>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: 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>

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

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

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

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: NMiguel Rodel Felipe <Rodel_FM@dsi.a-star.edu.sg>
Signed-off-by: NPhua Eu Gene <PHUA_Eu_Gene@dsi.a-star.edu.sg>
Signed-off-by: NKhin Mi Mi Aung <Mi_Mi_AUNG@dsi.a-star.edu.sg>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

We want to use the same credential for reclaim_complete as we used
for the exchange_id call.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

We shouldn't need to pass the 'cache_reply' parameter if we
initialise the sequence_args/sequence_res in the caller.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

Clean up. Gather NFSv4.1 slot definitions in fs/nfs/nfs4session.h.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

NFSv4.1 session management is getting complex enough to deserve
a separate file.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

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: NTrond Myklebust <Trond.Myklebust@netapp.com>

Instead of an array of slots, use a singly linked list of slots that
can be dynamically appended to or shrunk.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Ensure that the NFSv4.1 CB_RECALL_SLOT callback updates the slot table
target max slotid safely.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>