linux-toradex.git/fs/nfsd, branch v6.12-rc1

nfsd: implement server support for NFS_LOCALIO_PROGRAM

2024-09-23T19:03:30+00:00

The LOCALIO auxiliary RPC protocol consists of a single "UUID_IS_LOCAL"
RPC method that allows the Linux NFS client to verify the local Linux
NFS server can see the nonce (single-use UUID) the client generated and
made available in nfs_common.  The server expects this protocol to use
the same transport as NFS and NFSACL for its RPCs.  This protocol
isn't part of an IETF standard, nor does it need to be considering it
is Linux-to-Linux auxiliary RPC protocol that amounts to an
implementation detail.

The UUID_IS_LOCAL method encodes the client generated uuid_t in terms of
the fixed UUID_SIZE (16 bytes).  The fixed size opaque encode and decode
XDR methods are used instead of the less efficient variable sized
methods.

The RPC program number for the NFS_LOCALIO_PROGRAM is 400122 (as assigned
by IANA, see https://www.iana.org/assignments/rpc-program-numbers/ ):
Linux Kernel Organization       400122  nfslocalio

Signed-off-by: Mike Snitzer 
[neilb: factored out and simplified single localio protocol]
Co-developed-by: NeilBrown 
Signed-off-by: NeilBrown 
Acked-by: Chuck Lever 
Reviewed-by: Jeff Layton 
Signed-off-by: Anna Schumaker

nfsd: add LOCALIO support

2024-09-23T19:03:30+00:00

Add server support for bypassing NFS for localhost reads, writes, and
commits. This is only useful when both the client and server are
running on the same host.

If nfsd_open_local_fh() fails then the NFS client will both retry and
fallback to normal network-based read, write and commit operations if
localio is no longer supported.

Care is taken to ensure the same NFS security mechanisms are used
(authentication, etc) regardless of whether localio or regular NFS
access is used.  The auth_domain established as part of the traditional
NFS client access to the NFS server is also used for localio.  Store
auth_domain for localio in nfsd_uuid_t and transfer it to the client
if it is local to the server.

Relative to containers, localio gives the client access to the network
namespace the server has.  This is required to allow the client to
access the server's per-namespace nfsd_net struct.

This commit also introduces the use of NFSD's percpu_ref to interlock
nfsd_destroy_serv and nfsd_open_local_fh, to ensure nn->nfsd_serv is
not destroyed while in use by nfsd_open_local_fh and other LOCALIO
client code.

CONFIG_NFS_LOCALIO enables NFS server support for LOCALIO.

Signed-off-by: Weston Andros Adamson 
Signed-off-by: Trond Myklebust 
Co-developed-by: Mike Snitzer 
Signed-off-by: Mike Snitzer 
Co-developed-by: NeilBrown 
Signed-off-by: NeilBrown 
Reviewed-by: Jeff Layton 
Acked-by: Chuck Lever 
Signed-off-by: Anna Schumaker

nfs_common: prepare for the NFS client to use nfsd_file for LOCALIO

2024-09-23T19:03:30+00:00

The next commit will introduce nfsd_open_local_fh() which returns an
nfsd_file structure.  This commit exposes LOCALIO's required NFSD
symbols to the NFS client:

- Make nfsd_open_local_fh() symbol and other required NFSD symbols
  available to NFS in a global 'nfs_to' nfsd_localio_operations
  struct (global access suggested by Trond, nfsd_localio_operations
  suggested by NeilBrown).  The next commit will also introduce
  nfsd_localio_ops_init() that init_nfsd() will call to initialize
  'nfs_to'.

- Introduce nfsd_file_file() that provides access to nfsd_file's
  backing file.  Keeps nfsd_file structure opaque to NFS client (as
  suggested by Jeff Layton).

- Introduce nfsd_file_put_local() that will put the reference to the
  nfsd_file's associated nn->nfsd_serv and then put the reference to
  the nfsd_file (as suggested by NeilBrown).

Suggested-by: Trond Myklebust  # nfs_to
Suggested-by: NeilBrown  # nfsd_localio_operations
Suggested-by: Jeff Layton  # nfsd_file_file
Signed-off-by: Mike Snitzer 
Reviewed-by: NeilBrown 
Reviewed-by: Jeff Layton 
Signed-off-by: Anna Schumaker

SUNRPC: replace program list with program array

2024-09-23T19:03:30+00:00

A service created with svc_create_pooled() can be given a linked list of
programs and all of these will be served.

Using a linked list makes it cumbersome when there are several programs
that can be optionally selected with CONFIG settings.

After this patch is applied, API consumers must use only
svc_create_pooled() when creating an RPC service that listens for more
than one RPC program.

Signed-off-by: NeilBrown 
Signed-off-by: Mike Snitzer 
Acked-by: Chuck Lever 
Reviewed-by: Jeff Layton 
Signed-off-by: Anna Schumaker

nfsd: add nfsd_serv_try_get and nfsd_serv_put

2024-09-23T19:03:30+00:00

Introduce nfsd_serv_try_get and nfsd_serv_put and update the nfsd code
to prevent nfsd_destroy_serv from destroying nn->nfsd_serv until any
caller of nfsd_serv_try_get releases their reference using nfsd_serv_put.

A percpu_ref is used to implement the interlock between
nfsd_destroy_serv and any caller of nfsd_serv_try_get.

This interlock is needed to properly wait for the completion of client
initiated localio calls to nfsd (that are _not_ in the context of nfsd).

Signed-off-by: Mike Snitzer 
Reviewed-by: Chuck Lever 
Reviewed-by: Jeff Layton 
Reviewed-by: NeilBrown 
Signed-off-by: Anna Schumaker

nfsd: add nfsd_file_acquire_local()

2024-09-23T19:03:30+00:00

nfsd_file_acquire_local() can be used to look up a file by filehandle
without having a struct svc_rqst.  This can be used by NFS LOCALIO to
allow the NFS client to bypass the NFS protocol to directly access a
file provided by the NFS server which is running in the same kernel.

In nfsd_file_do_acquire() care is taken to always use fh_verify() if
rqstp is not NULL (as is the case for non-LOCALIO callers).  Otherwise
the non-LOCALIO callers will not supply the correct and required
arguments to __fh_verify (e.g. gssclient isn't passed).

Introduce fh_verify_local() wrapper around __fh_verify to make it
clear that LOCALIO is intended caller.

Also, use GC for nfsd_file returned by nfsd_file_acquire_local.  GC
offers performance improvements if/when a file is reopened before
launderette cleans it from the filecache's LRU.

Suggested-by: Jeff Layton  # use filecache's GC
Signed-off-by: NeilBrown 
Co-developed-by: Mike Snitzer 
Signed-off-by: Mike Snitzer 
Signed-off-by: Chuck Lever 
Reviewed-by: Jeff Layton 
Signed-off-by: Anna Schumaker

nfsd: factor out __fh_verify to allow NULL rqstp to be passed

2024-09-23T19:03:30+00:00

__fh_verify() offers an interface like fh_verify() but doesn't require
a struct svc_rqst *, instead it also takes the specific parts as
explicit required arguments.  So it is safe to call __fh_verify() with
a NULL rqstp, but the net, cred, and client args must not be NULL.

__fh_verify() does not use SVC_NET(), nor does the functions it calls.

Rather than using rqstp->rq_client pass the client and gssclient
explicitly to __fh_verify and then to nfsd_set_fh_dentry().

Lastly, it should be noted that the previous commit prepared for 4
associated tracepoints to only be used if rqstp is not NULL (this is a
stop-gap that should be properly fixed so localio also benefits from
the utility these tracepoints provide when debugging fh_verify
issues).

Signed-off-by: NeilBrown 
Co-developed-by: Mike Snitzer 
Signed-off-by: Mike Snitzer 
Signed-off-by: Chuck Lever 
Reviewed-by: Jeff Layton 
Signed-off-by: Anna Schumaker

NFSD: Short-circuit fh_verify tracepoints for LOCALIO

2024-09-23T19:03:30+00:00

LOCALIO will be able to call fh_verify() with a NULL rqstp. In this
case, the existing trace points need to be skipped because they
want to dereference the address fields in the passed-in rqstp.

Temporarily make these trace points conditional to avoid a seg
fault in this case. Putting the "rqstp != NULL" check in the trace
points themselves makes the check more efficient.

Signed-off-by: Chuck Lever 
Signed-off-by: Mike Snitzer 
Acked-by: Jeff Layton 
Reviewed-by: NeilBrown 
Signed-off-by: Anna Schumaker

NFSD: Avoid using rqstp->rq_vers in nfsd_set_fh_dentry()

2024-09-23T19:03:30+00:00

Currently, fh_verify() makes some daring assumptions about which
version of file handle the caller wants, based on the things it can
find in the passed-in rqstp. The about-to-be-introduced LOCALIO use
case sometimes has no svc_rqst context, so this logic won't work in
that case.

Instead, examine the passed-in file handle. It's .max_size field
should carry information to allow nfsd_set_fh_dentry() to initialize
the file handle appropriately.

The file handle used by lockd and the one created by write_filehandle
never need any of the version-specific fields (which affect things
like write and getattr requests and pre/post attributes).

Signed-off-by: Chuck Lever 
Signed-off-by: Mike Snitzer 
Reviewed-by: Jeff Layton 
Reviewed-by: NeilBrown 
Signed-off-by: Anna Schumaker

NFSD: Refactor nfsd_setuser_and_check_port()

2024-09-23T19:03:30+00:00

There are several places where __fh_verify unconditionally dereferences
rqstp to check that the connection is suitably secure.  They look at
rqstp->rq_xprt which is not meaningful in the target use case of
"localio" NFS in which the client talks directly to the local server.

Prepare these to always succeed when rqstp is NULL.

Signed-off-by: NeilBrown 
Co-developed-by: Mike Snitzer 
Signed-off-by: Mike Snitzer 
Signed-off-by: Chuck Lever 
Reviewed-by: Jeff Layton 
Signed-off-by: Anna Schumaker