SUNRPC: Report network/connection errors correctly for SOFTCONN rpc tasks

In the case of a SOFTCONN rpc task, we really want to ensure that it
reports errors like ENETUNREACH back to the caller. Currently, only
some of these errors are being reported back (connect errors are not),
and they are being converted by the RPC layer into EIO.

Reported-by: Jan Engelhardt <jengelh@inai.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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etc, fail with an EBADF to indicate that this file descriptor is no
longer valid.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>
NFS: Don't accept more reads/writes if the open context recovery failed

If the state recovery failed, we want to ensure that the application
doesn't try to use the same file descriptor for more reads or writes.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFS: __nfs_find_lock_context needs to check ctx->lock_context for a match too

Currently, we're forcing an unnecessary duplication of the
initial nfs_lock_context in calls to nfs_get_lock_context, since
__nfs_find_lock_context ignores the ctx->lock_context.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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>
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>
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>
NFSv4.1: Select the "most recent locking state" for read/write/setattr stateids

Follow the practice described in section 8.2.2 of RFC5661: When sending a
read/write or setattr stateid, set the seqid field to zero in order to
signal that the NFS server should apply the most recent locking state.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4: Clean up nfs4_opendata_alloc in preparation for NFSv4.1 open modes

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4.1: Add xdr support for CLAIM_FH and CLAIM_DELEG_CUR_FH opens

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4.1: Enable open-by-filehandle

Sometimes, we actually _want_ to do open-by-filehandle, for instance
when recovering opens after a network partition, or when called
from nfs4_file_open.
Enable that functionality using a new capability NFS_CAP_ATOMIC_OPEN_V1,
and which is only enabled for NFSv4.1 servers that support it.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4.1: Use CLAIM_DELEG_CUR_FH opens when available

Now that we do CLAIM_FH opens, we may run into situations where we
get a delegation but don't have perfect knowledge of the file path.
When returning the delegation, we might therefore not be able to
us CLAIM_DELEGATE_CUR opens to convert the delegation into OPEN
stateids and locks.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4: Add a mapping for NFS4ERR_FILE_OPEN in nfs4_map_errors

With unlink is an asynchronous operation in the sillyrename case, it
expects nfs4_async_handle_error() to map the error correctly.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4: Fix another reboot recovery race

If the open_context for the file is not yet fully initialised,
then open recovery cannot succeed, and since nfs4_state_find_open_context
returns an ENOENT, we end up treating the file as being irrecoverable.

What we really want to do, is just defer the recovery until later.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFSv4: Fix Oopses in the fs_locations code

If the server sends us a pathname with more components than the client
limit of NFS4_PATHNAME_MAXCOMPONENTS, more server entries than the client
limit of NFS4_FS_LOCATION_MAXSERVERS, or sends a total number of
fs_locations entries than the client limit of NFS4_FS_LOCATIONS_MAXENTRIES
then we will currently Oops because the limit checks are done _after_ we've
decoded the data into the arrays.

Reported-by: fanchaoting<fanchaoting@cn.fujitsu.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
SUNRPC: Missing module alias for auth_rpcgss.ko

Commit f344f6df "SUNRPC: Auto-load RPC authentication kernel
modules", Mon Mar 20 13:44:08 2006, adds a request_module() call
in rpcauth_create() to auto-load RPC security modules when a ULP
tries to create a credential of that flavor.

In rpcauth_create(), the name of the module to load is built like
this:

	request_module("rpc-auth-%u", flavor);

This means that for, say, RPC_AUTH_GSS, request_module() is looking
for a module or alias called "rpc-auth-6".

The GSS module is named "auth_rpcgss", and commit f344f6df does not
add any new module aliases.  There is also no such alias provided in
/etc/modprobe.d on my system (Fedora 16).  Without this alias, the
GSS module is not loaded on demand.

This is used by rpcauth_create().  The pseudoflavor_to_flavor() call
can return RPC_AUTH_GSS, which is passed to request_module().

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
NFS: Remove unneeded forward declaration

I've built with NFSv4 enabled and disabled.  This forward
declaration does not seem to be required.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
SUNRPC: Define rpcsec_gss_info structure

The NFSv4 SECINFO procedure returns a list of security flavors.  Any
GSS flavor also has a GSS tuple containing an OID, a quality-of-
protection value, and a service value, which specifies a particular
GSS pseudoflavor.

For simplicity and efficiency, I'd like to return each GSS tuple
from the NFSv4 SECINFO XDR decoder and pass it straight into the RPC
client.

Define a data structure that is visible to both the NFS client and
the RPC client.  Take structure and field names from the relevant
standards to avoid confusion.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
SUNRPC: Introduce rpcauth_get_pseudoflavor()

A SECINFO reply may contain flavors whose kernel module is not
yet loaded by the client's kernel.  A new RPC client API, called
rpcauth_get_pseudoflavor(), is introduced to do proper checking
for support of a security flavor.

When this API is invoked, the RPC client now tries to load the
module for each flavor first before performing the "is this
supported?" check.  This means if a module is available on the
client, but has not been loaded yet, it will be loaded and
registered automatically when the SECINFO reply is processed.

The new API can take a full GSS tuple (OID, QoP, and service).
Previously only the OID and service were considered.

nfs_find_best_sec() is updated to verify all flavors requested in a
SECINFO reply, including AUTH_NULL and AUTH_UNIX.  Previously these
two flavors were simply assumed to be supported without consulting
the RPC client.

Note that the replaced version of nfs_find_best_sec() can return
RPC_AUTH_MAXFLAVOR if the server returns a recognized OID but an
unsupported "service" value.  nfs_find_best_sec() now returns
RPC_AUTH_UNIX in this case.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
SUNRPC: Load GSS kernel module by OID

The current GSS mech switch can find and load GSS pseudoflavor
modules by name ("krb5") or pseudoflavor number ("390003"), but
cannot find GSS modules by GSS tuple:

  [ "1.2.840.113554.1.2.2", GSS_C_QOP_DEFAULT, RPC_GSS_SVC_NONE ]

This is important when dealing with a SECINFO request.  A SECINFO
reply contains a list of flavors the server supports for the
requested export, but GSS flavors also have a GSS tuple that maps
to a pseudoflavor (like 390003 for krb5).

If the GSS module that supports the OID in the tuple is not loaded,
our client is not able to load that module dynamically to support
that pseudoflavor.

Add a way for the GSS mech switch to load GSS pseudoflavor support
by OID before searching for the pseudoflavor that matches the OID
and service.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>