Re: [PATCH v8 07/18] nfsd: add "localio" support

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2024-06-26 at 14:24 -0400, Mike Snitzer wrote:
> Pass the stored cl_nfssvc_net from the client to the server as
> first argument to nfsd_open_local_fh() to ensure the proper network
> namespace is used for localio.
> 
> Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
> Signed-off-by: Peng Tao <tao.peng@primarydata.com>
> Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
> ---
>  fs/nfsd/Makefile    |   1 +
>  fs/nfsd/filecache.c |   2 +-
>  fs/nfsd/localio.c   | 246 ++++++++++++++++++++++++++++++++++++++++++++
>  fs/nfsd/nfssvc.c    |   1 +
>  fs/nfsd/trace.h     |   3 +-
>  fs/nfsd/vfs.h       |   9 ++
>  6 files changed, 260 insertions(+), 2 deletions(-)
>  create mode 100644 fs/nfsd/localio.c
> 
> diff --git a/fs/nfsd/Makefile b/fs/nfsd/Makefile
> index b8736a82e57c..78b421778a79 100644
> --- a/fs/nfsd/Makefile
> +++ b/fs/nfsd/Makefile
> @@ -23,3 +23,4 @@ nfsd-$(CONFIG_NFSD_PNFS) += nfs4layouts.o
>  nfsd-$(CONFIG_NFSD_BLOCKLAYOUT) += blocklayout.o blocklayoutxdr.o
>  nfsd-$(CONFIG_NFSD_SCSILAYOUT) += blocklayout.o blocklayoutxdr.o
>  nfsd-$(CONFIG_NFSD_FLEXFILELAYOUT) += flexfilelayout.o flexfilelayoutxdr.o
> +nfsd-$(CONFIG_NFSD_LOCALIO) += localio.o
> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> index ad9083ca144b..99631fa56662 100644
> --- a/fs/nfsd/filecache.c
> +++ b/fs/nfsd/filecache.c
> @@ -52,7 +52,7 @@
>  #define NFSD_FILE_CACHE_UP		     (0)
>  
>  /* We only care about NFSD_MAY_READ/WRITE for this cache */
> -#define NFSD_FILE_MAY_MASK	(NFSD_MAY_READ|NFSD_MAY_WRITE)
> +#define NFSD_FILE_MAY_MASK	(NFSD_MAY_READ|NFSD_MAY_WRITE|NFSD_MAY_LOCALIO)
>  
>  static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
>  static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions);
> diff --git a/fs/nfsd/localio.c b/fs/nfsd/localio.c
> new file mode 100644
> index 000000000000..ba9187735947
> --- /dev/null
> +++ b/fs/nfsd/localio.c
> @@ -0,0 +1,246 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * NFS server support for local clients to bypass network stack
> + *
> + * Copyright (C) 2014 Weston Andros Adamson <dros@primarydata.com>
> + * Copyright (C) 2019 Trond Myklebust <trond.myklebust@hammerspace.com>
> + * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
> + */
> +
> +#include <linux/exportfs.h>
> +#include <linux/sunrpc/svcauth_gss.h>
> +#include <linux/sunrpc/clnt.h>
> +#include <linux/nfs.h>
> +#include <linux/string.h>
> +
> +#include "nfsd.h"
> +#include "vfs.h"
> +#include "netns.h"
> +#include "filecache.h"
> +
> +#define NFSDDBG_FACILITY		NFSDDBG_FH
> +
> +/*
> + * We need to translate between nfs status return values and
> + * the local errno values which may not be the same.
> + * - duplicated from fs/nfs/nfs2xdr.c to avoid needless bloat of
> + *   all compiled nfs objects if it were in include/linux/nfs.h
> + */
> +static const struct {
> +	int stat;
> +	int errno;
> +} nfs_common_errtbl[] = {
> +	{ NFS_OK,		0		},
> +	{ NFSERR_PERM,		-EPERM		},
> +	{ NFSERR_NOENT,		-ENOENT		},
> +	{ NFSERR_IO,		-EIO		},
> +	{ NFSERR_NXIO,		-ENXIO		},
> +/*	{ NFSERR_EAGAIN,	-EAGAIN		}, */
> +	{ NFSERR_ACCES,		-EACCES		},
> +	{ NFSERR_EXIST,		-EEXIST		},
> +	{ NFSERR_XDEV,		-EXDEV		},
> +	{ NFSERR_NODEV,		-ENODEV		},
> +	{ NFSERR_NOTDIR,	-ENOTDIR	},
> +	{ NFSERR_ISDIR,		-EISDIR		},
> +	{ NFSERR_INVAL,		-EINVAL		},
> +	{ NFSERR_FBIG,		-EFBIG		},
> +	{ NFSERR_NOSPC,		-ENOSPC		},
> +	{ NFSERR_ROFS,		-EROFS		},
> +	{ NFSERR_MLINK,		-EMLINK		},
> +	{ NFSERR_NAMETOOLONG,	-ENAMETOOLONG	},
> +	{ NFSERR_NOTEMPTY,	-ENOTEMPTY	},
> +	{ NFSERR_DQUOT,		-EDQUOT		},
> +	{ NFSERR_STALE,		-ESTALE		},
> +	{ NFSERR_REMOTE,	-EREMOTE	},
> +#ifdef EWFLUSH
> +	{ NFSERR_WFLUSH,	-EWFLUSH	},
> +#endif
> +	{ NFSERR_BADHANDLE,	-EBADHANDLE	},
> +	{ NFSERR_NOT_SYNC,	-ENOTSYNC	},
> +	{ NFSERR_BAD_COOKIE,	-EBADCOOKIE	},
> +	{ NFSERR_NOTSUPP,	-ENOTSUPP	},
> +	{ NFSERR_TOOSMALL,	-ETOOSMALL	},
> +	{ NFSERR_SERVERFAULT,	-EREMOTEIO	},
> +	{ NFSERR_BADTYPE,	-EBADTYPE	},
> +	{ NFSERR_JUKEBOX,	-EJUKEBOX	},
> +	{ -1,			-EIO		}
> +};
> +
> +/**
> + * nfs_stat_to_errno - convert an NFS status code to a local errno
> + * @status: NFS status code to convert
> + *
> + * Returns a local errno value, or -EIO if the NFS status code is
> + * not recognized.  nfsd_file_acquire() returns an nfsstat that
> + * needs to be translated to an errno before being returned to a
> + * local client application.
> + */
> +static int nfs_stat_to_errno(enum nfs_stat status)
> +{
> +	int i;
> +
> +	for (i = 0; nfs_common_errtbl[i].stat != -1; i++) {
> +		if (nfs_common_errtbl[i].stat == (int)status)
> +			return nfs_common_errtbl[i].errno;
> +	}
> +	return nfs_common_errtbl[i].errno;
> +}
> +
> +static void
> +nfsd_local_fakerqst_destroy(struct svc_rqst *rqstp)
> +{
> +	if (rqstp->rq_client)
> +		auth_domain_put(rqstp->rq_client);
> +	if (rqstp->rq_cred.cr_group_info)
> +		put_group_info(rqstp->rq_cred.cr_group_info);
> +	/* rpcauth_map_to_svc_cred_local() clears cr_principal */
> +	WARN_ON_ONCE(rqstp->rq_cred.cr_principal != NULL);
> +	kfree(rqstp->rq_xprt);
> +	kfree(rqstp);
> +}
> +
> +static struct svc_rqst *
> +nfsd_local_fakerqst_create(struct net *net, struct rpc_clnt *rpc_clnt,
> +			const struct cred *cred)
> +{
> +	struct svc_rqst *rqstp;
> +	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> +	int status;
> +
> +	/* FIXME: not running in nfsd context, must get reference on nfsd_serv */
> +	if (unlikely(!READ_ONCE(nn->nfsd_serv))) {
> +		dprintk("%s: localio denied. Server not running\n", __func__);

Chuck mentioned this earlier, but I don't think we ought to merge the
dprintks. If they're useful for debugging then they should be turned
into tracepoints. This one, I'd probably just drop.

> +		return ERR_PTR(-ENXIO);
> +	}
> +
> +	rqstp = kzalloc(sizeof(*rqstp), GFP_KERNEL);
> +	if (!rqstp)
> +		return ERR_PTR(-ENOMEM);
> +
> +	rqstp->rq_xprt = kzalloc(sizeof(*rqstp->rq_xprt), GFP_KERNEL);
> +	if (!rqstp->rq_xprt) {
> +		status = -ENOMEM;
> +		goto out_err;
> +	}
> +
> +	rqstp->rq_xprt->xpt_net = net;
> +	__set_bit(RQ_SECURE, &rqstp->rq_flags);
> +	rqstp->rq_proc = 1;
> +	rqstp->rq_vers = 3;
> +	rqstp->rq_prot = IPPROTO_TCP;
> +	rqstp->rq_server = nn->nfsd_serv;
> +
> +	/* Note: we're connecting to ourself, so source addr == peer addr */
> +	rqstp->rq_addrlen = rpc_peeraddr(rpc_clnt,
> +			(struct sockaddr *)&rqstp->rq_addr,
> +			sizeof(rqstp->rq_addr));
> +
> +	rpcauth_map_to_svc_cred_local(rpc_clnt->cl_auth, cred, &rqstp->rq_cred);
> +
> +	/*
> +	 * set up enough for svcauth_unix_set_client to be able to wait
> +	 * for the cache downcall. Note that we do _not_ want to allow the
> +	 * request to be deferred for later revisit since this rqst and xprt
> +	 * are not set up to run inside of the normal svc_rqst engine.
> +	 */
> +	INIT_LIST_HEAD(&rqstp->rq_xprt->xpt_deferred);
> +	kref_init(&rqstp->rq_xprt->xpt_ref);
> +	spin_lock_init(&rqstp->rq_xprt->xpt_lock);
> +	rqstp->rq_chandle.thread_wait = 5 * HZ;
> +
> +	status = svcauth_unix_set_client(rqstp);
> +	switch (status) {
> +	case SVC_OK:
> +		break;
> +	case SVC_DENIED:
> +		status = -ENXIO;
> +		dprintk("%s: client %pISpc denied localio access\n",
> +				__func__, (struct sockaddr *)&rqstp->rq_addr);
> +		goto out_err;
> +	default:
> +		status = -ETIMEDOUT;
> +		dprintk("%s: client %pISpc temporarily denied localio access\n",
> +				__func__, (struct sockaddr *)&rqstp->rq_addr);
> +		goto out_err;
> +	}
> +
> +	return rqstp;
> +
> +out_err:

The two above can probably be turned into a single tracepoint here,
though it might just be best to have a single tracepoint that always
fires when this function exits.

> +	nfsd_local_fakerqst_destroy(rqstp);
> +	return ERR_PTR(status);
> +}
> +
> +/*
> + * nfsd_open_local_fh - lookup a local filehandle @nfs_fh and map to @file
> + *
> + * This function maps a local fh to a path on a local filesystem.
> + * This is useful when the nfs client has the local server mounted - it can
> + * avoid all the NFS overhead with reads, writes and commits.
> + *
> + * on successful return, caller is responsible for calling path_put. Also
> + * note that this is called from nfs.ko via find_symbol() to avoid an explicit
> + * dependency on knfsd. So, there is no forward declaration in a header file
> + * for it.
> + */
> +int nfsd_open_local_fh(struct net *net,
> +			 struct rpc_clnt *rpc_clnt,
> +			 const struct cred *cred,
> +			 const struct nfs_fh *nfs_fh,
> +			 const fmode_t fmode,
> +			 struct file **pfilp)
> +{
> +	const struct cred *save_cred;
> +	struct svc_rqst *rqstp;
> +	struct svc_fh fh;
> +	struct nfsd_file *nf;
> +	int status = 0;
> +	int mayflags = NFSD_MAY_LOCALIO;
> +	__be32 beres;
> +
> +	/* Save creds before calling into nfsd */
> +	save_cred = get_current_cred();
> +
> +	rqstp = nfsd_local_fakerqst_create(net, rpc_clnt, cred);
> +	if (IS_ERR(rqstp)) {
> +		status = PTR_ERR(rqstp);
> +		goto out_revertcred;
> +	}
> +
> +	/* nfs_fh -> svc_fh */
> +	if (nfs_fh->size > NFS4_FHSIZE) {
> +		status = -EINVAL;
> +		goto out;
> +	}
> +	fh_init(&fh, NFS4_FHSIZE);
> +	fh.fh_handle.fh_size = nfs_fh->size;
> +	memcpy(fh.fh_handle.fh_raw, nfs_fh->data, nfs_fh->size);
> +
> +	if (fmode & FMODE_READ)
> +		mayflags |= NFSD_MAY_READ;
> +	if (fmode & FMODE_WRITE)
> +		mayflags |= NFSD_MAY_WRITE;
> +
> +	beres = nfsd_file_acquire(rqstp, &fh, mayflags, &nf);
> +	if (beres) {
> +		status = nfs_stat_to_errno(be32_to_cpu(beres));
> +		dprintk("%s: fh_verify failed %d\n", __func__, status);

This should also be a tracepoint.

> +		goto out_fh_put;
> +	}
> +
> +	*pfilp = get_file(nf->nf_file);
> +
> +	nfsd_file_put(nf);
> +out_fh_put:
> +	fh_put(&fh);
> +
> +out:
> +	nfsd_local_fakerqst_destroy(rqstp);
> +out_revertcred:
> +	revert_creds(save_cred);
> +	return status;
> +}
> +EXPORT_SYMBOL_GPL(nfsd_open_local_fh);
> +
> +/* Compile time type checking, not used by anything */
> +static nfs_to_nfsd_open_t __maybe_unused nfsd_open_local_fh_typecheck = nfsd_open_local_fh;
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index 1222a0a33fe1..a477d2c5088a 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -431,6 +431,7 @@ static int nfsd_startup_net(struct net *net, const struct cred *cred)
>  #endif
>  #if IS_ENABLED(CONFIG_NFSD_LOCALIO)
>  	INIT_LIST_HEAD(&nn->nfsd_uuid.list);
> +	nn->nfsd_uuid.net = net;
>  	list_add_tail_rcu(&nn->nfsd_uuid.list, &nfsd_uuids);
>  #endif
>  	nn->nfsd_net_up = true;
> diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
> index 77bbd23aa150..9c0610fdd11c 100644
> --- a/fs/nfsd/trace.h
> +++ b/fs/nfsd/trace.h
> @@ -86,7 +86,8 @@ DEFINE_NFSD_XDR_ERR_EVENT(cant_encode);
>  		{ NFSD_MAY_NOT_BREAK_LEASE,	"NOT_BREAK_LEASE" },	\
>  		{ NFSD_MAY_BYPASS_GSS,		"BYPASS_GSS" },		\
>  		{ NFSD_MAY_READ_IF_EXEC,	"READ_IF_EXEC" },	\
> -		{ NFSD_MAY_64BIT_COOKIE,	"64BIT_COOKIE" })
> +		{ NFSD_MAY_64BIT_COOKIE,	"64BIT_COOKIE" },	\
> +		{ NFSD_MAY_LOCALIO,		"LOCALIO" })
>  
>  TRACE_EVENT(nfsd_compound,
>  	TP_PROTO(
> diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
> index 57cd70062048..5146f0c81752 100644
> --- a/fs/nfsd/vfs.h
> +++ b/fs/nfsd/vfs.h
> @@ -33,6 +33,8 @@
>  
>  #define NFSD_MAY_64BIT_COOKIE		0x1000 /* 64 bit readdir cookies for >= NFSv3 */
>  
> +#define NFSD_MAY_LOCALIO		0x2000
> +
>  #define NFSD_MAY_CREATE		(NFSD_MAY_EXEC|NFSD_MAY_WRITE)
>  #define NFSD_MAY_REMOVE		(NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC)
>  
> @@ -158,6 +160,13 @@ __be32		nfsd_permission(struct svc_rqst *, struct svc_export *,
>  
>  void		nfsd_filp_close(struct file *fp);
>  
> +int		nfsd_open_local_fh(struct net *net,
> +				   struct rpc_clnt *rpc_clnt,
> +				   const struct cred *cred,
> +				   const struct nfs_fh *nfs_fh,
> +				   const fmode_t fmode,
> +				   struct file **pfilp);
> +
>  static inline int fh_want_write(struct svc_fh *fh)
>  {
>  	int ret;

-- 
Jeff Layton <jlayton@kernel.org>