fs/nfs/mount_clnt.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * In-kernel MOUNT protocol client
  *
  * Copyright (C) 1997, Olaf Kirch <okir@monad.swb.de>
  */

 #include <linux/types.h>
 #include <linux/socket.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/uio.h>
 #include <linux/net.h>
 #include <linux/in.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/sched.h>
 #include <linux/nfs_fs.h>
 #include "internal.h"

 #define NFSDBG_FACILITY	NFSDBG_MOUNT

 /*
  * Defined by RFC 1094, section A.3; and RFC 1813, section 5.1.4
  */
 #define MNTPATHLEN		(1024)

 /*
  * XDR data type sizes
  */
 #define encode_dirpath_sz	(1 + XDR_QUADLEN(MNTPATHLEN))
 #define MNT_status_sz		(1)
 #define MNT_fhandle_sz		XDR_QUADLEN(NFS2_FHSIZE)
 #define MNT_fhandlev3_sz	XDR_QUADLEN(NFS3_FHSIZE)
 #define MNT_authflav3_sz	(1 + NFS_MAX_SECFLAVORS)

 /*
  * XDR argument and result sizes
  */
 #define MNT_enc_dirpath_sz	encode_dirpath_sz
 #define MNT_dec_mountres_sz	(MNT_status_sz + MNT_fhandle_sz)
 #define MNT_dec_mountres3_sz	(MNT_status_sz + MNT_fhandlev3_sz + \
 				 MNT_authflav3_sz)

 /*
  * Defined by RFC 1094, section A.5
  */
 enum {
 	MOUNTPROC_NULL		= 0,
 	MOUNTPROC_MNT		= 1,
 	MOUNTPROC_DUMP		= 2,
 	MOUNTPROC_UMNT		= 3,
 	MOUNTPROC_UMNTALL	= 4,
 	MOUNTPROC_EXPORT	= 5,
 };

 /*
  * Defined by RFC 1813, section 5.2
  */
 enum {
 	MOUNTPROC3_NULL		= 0,
 	MOUNTPROC3_MNT		= 1,
 	MOUNTPROC3_DUMP		= 2,
 	MOUNTPROC3_UMNT		= 3,
 	MOUNTPROC3_UMNTALL	= 4,
 	MOUNTPROC3_EXPORT	= 5,
 };

 static const struct rpc_program mnt_program;

 /*
  * Defined by OpenGroup XNFS Version 3W, chapter 8
  */
 enum mountstat {
 	MNT_OK			= 0,
 	MNT_EPERM		= 1,
 	MNT_ENOENT		= 2,
 	MNT_EACCES		= 13,
 	MNT_EINVAL		= 22,
 };

 static struct {
 	u32 status;
 	int errno;
 } mnt_errtbl[] = {
 	{ .status = MNT_OK,			.errno = 0,		},
 	{ .status = MNT_EPERM,			.errno = -EPERM,	},
 	{ .status = MNT_ENOENT,			.errno = -ENOENT,	},
 	{ .status = MNT_EACCES,			.errno = -EACCES,	},
 	{ .status = MNT_EINVAL,			.errno = -EINVAL,	},
 };

 /*
  * Defined by RFC 1813, section 5.1.5
  */
 enum mountstat3 {
 	MNT3_OK			= 0,		/* no error */
 	MNT3ERR_PERM		= 1,		/* Not owner */
 	MNT3ERR_NOENT		= 2,		/* No such file or directory */
 	MNT3ERR_IO		= 5,		/* I/O error */
 	MNT3ERR_ACCES		= 13,		/* Permission denied */
 	MNT3ERR_NOTDIR		= 20,		/* Not a directory */
 	MNT3ERR_INVAL		= 22,		/* Invalid argument */
 	MNT3ERR_NAMETOOLONG	= 63,		/* Filename too long */
 	MNT3ERR_NOTSUPP		= 10004,	/* Operation not supported */
 	MNT3ERR_SERVERFAULT	= 10006,	/* A failure on the server */
 };

 static struct {
 	u32 status;
 	int errno;
 } mnt3_errtbl[] = {
 	{ .status = MNT3_OK,			.errno = 0,		},
 	{ .status = MNT3ERR_PERM,		.errno = -EPERM,	},
 	{ .status = MNT3ERR_NOENT,		.errno = -ENOENT,	},
 	{ .status = MNT3ERR_IO,			.errno = -EIO,		},
 	{ .status = MNT3ERR_ACCES,		.errno = -EACCES,	},
 	{ .status = MNT3ERR_NOTDIR,		.errno = -ENOTDIR,	},
 	{ .status = MNT3ERR_INVAL,		.errno = -EINVAL,	},
 	{ .status = MNT3ERR_NAMETOOLONG,	.errno = -ENAMETOOLONG,	},
 	{ .status = MNT3ERR_NOTSUPP,		.errno = -ENOTSUPP,	},
 	{ .status = MNT3ERR_SERVERFAULT,	.errno = -EREMOTEIO,	},
 };

 struct mountres {
 	int errno;
 	struct nfs_fh *fh;
 	unsigned int *auth_count;
 	rpc_authflavor_t *auth_flavors;
 };

 /**
  * nfs_mount - Obtain an NFS file handle for the given host and path
  * @info: pointer to mount request arguments
  * @timeo: deciseconds the mount waits for a response before it retries
  * @retrans: number of times the mount retries a request
  *
  * Uses timeout parameters specified by caller. On successful return, the
  * auth_flavs list and auth_flav_len will be populated with the list from the
  * server or a faked-up list if the server didn't provide one.
  */
 int nfs_mount(struct nfs_mount_request *info, int timeo, int retrans)
 {
 	struct rpc_timeout mnt_timeout;
 	struct mountres	result = {
 		.fh		= info->fh,
 		.auth_count	= info->auth_flav_len,
 		.auth_flavors	= info->auth_flavs,
 	};
 	struct rpc_message msg	= {
 		.rpc_argp	= info->dirpath,
 		.rpc_resp	= &result,
 	};
 	struct rpc_create_args args = {
 		.net		= info->net,
 		.protocol	= info->protocol,
 		.address	= (struct sockaddr *)info->sap,
 		.addrsize	= info->salen,
 		.timeout	= &mnt_timeout,
 		.servername	= info->hostname,
 		.program	= &mnt_program,
 		.version	= info->version,
 		.authflavor	= RPC_AUTH_UNIX,
 		.cred		= current_cred(),
 	};
 	struct rpc_clnt		*mnt_clnt;
 	int			status;

 	dprintk("NFS: sending MNT request for %s:%s\n",
 		(info->hostname ? info->hostname : "server"),
 			info->dirpath);

 	if (strlen(info->dirpath) > MNTPATHLEN)
 		return -ENAMETOOLONG;

 	if (info->noresvport)
 		args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;

 	nfs_init_timeout_values(&mnt_timeout, info->protocol, timeo, retrans);
 	mnt_clnt = rpc_create(&args);
 	if (IS_ERR(mnt_clnt))
 		goto out_clnt_err;

 	if (info->version == NFS_MNT3_VERSION)
 		msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC3_MNT];
 	else
 		msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC_MNT];

 	status = rpc_call_sync(mnt_clnt, &msg, RPC_TASK_SOFT|RPC_TASK_TIMEOUT);
 	rpc_shutdown_client(mnt_clnt);

 	if (status < 0)
 		goto out_call_err;
 	if (result.errno != 0)
 		goto out_mnt_err;

 	dprintk("NFS: MNT request succeeded\n");
 	status = 0;

 	/*
 	 * If the server didn't provide a flavor list, allow the
 	 * client to try any flavor.
 	 */
 	if (info->version != NFS_MNT3_VERSION || *info->auth_flav_len == 0) {
 		dprintk("NFS: Faking up auth_flavs list\n");
 		info->auth_flavs[0] = RPC_AUTH_NULL;
 		*info->auth_flav_len = 1;
 	}
 out:
 	return status;

 out_clnt_err:
 	status = PTR_ERR(mnt_clnt);
 	dprintk("NFS: failed to create MNT RPC client, status=%d\n", status);
 	goto out;

 out_call_err:
 	dprintk("NFS: MNT request failed, status=%d\n", status);
 	goto out;

 out_mnt_err:
 	dprintk("NFS: MNT server returned result %d\n", result.errno);
 	status = result.errno;
 	goto out;
 }

 /**
  * nfs_umount - Notify a server that we have unmounted this export
  * @info: pointer to umount request arguments
  *
  * MOUNTPROC_UMNT is advisory, so we set a short timeout, and always
  * use UDP.
  */
 void nfs_umount(const struct nfs_mount_request *info)
 {
 	static const struct rpc_timeout nfs_umnt_timeout = {
 		.to_initval = 1 * HZ,
 		.to_maxval = 3 * HZ,
 		.to_retries = 2,
 	};
 	struct rpc_create_args args = {
 		.net		= info->net,
 		.protocol	= IPPROTO_UDP,
 		.address	= (struct sockaddr *)info->sap,
 		.addrsize	= info->salen,
 		.timeout	= &nfs_umnt_timeout,
 		.servername	= info->hostname,
 		.program	= &mnt_program,
 		.version	= info->version,
 		.authflavor	= RPC_AUTH_UNIX,
 		.flags		= RPC_CLNT_CREATE_NOPING,
 		.cred		= current_cred(),
 	};
 	struct rpc_message msg	= {
 		.rpc_argp	= info->dirpath,
 	};
 	struct rpc_clnt *clnt;
 	int status;

 	if (strlen(info->dirpath) > MNTPATHLEN)
 		return;

 	if (info->noresvport)
 		args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;

 	clnt = rpc_create(&args);
 	if (IS_ERR(clnt))
 		goto out_clnt_err;

 	dprintk("NFS: sending UMNT request for %s:%s\n",
 		(info->hostname ? info->hostname : "server"), info->dirpath);

 	if (info->version == NFS_MNT3_VERSION)
 		msg.rpc_proc = &clnt->cl_procinfo[MOUNTPROC3_UMNT];
 	else
 		msg.rpc_proc = &clnt->cl_procinfo[MOUNTPROC_UMNT];

 	status = rpc_call_sync(clnt, &msg, 0);
 	rpc_shutdown_client(clnt);

 	if (unlikely(status < 0))
 		goto out_call_err;

 	return;

 out_clnt_err:
 	dprintk("NFS: failed to create UMNT RPC client, status=%ld\n",
 			PTR_ERR(clnt));
 	return;

 out_call_err:
 	dprintk("NFS: UMNT request failed, status=%d\n", status);
 }

 /*
  * XDR encode/decode functions for MOUNT
  */

 static void encode_mntdirpath(struct xdr_stream *xdr, const char *pathname)
 {
 	const u32 pathname_len = strlen(pathname);
 	__be32 *p;

 	p = xdr_reserve_space(xdr, 4 + pathname_len);
 	xdr_encode_opaque(p, pathname, pathname_len);
 }

 static void mnt_xdr_enc_dirpath(struct rpc_rqst *req, struct xdr_stream *xdr,
 				const void *dirpath)
 {
 	encode_mntdirpath(xdr, dirpath);
 }

 /*
  * RFC 1094: "A non-zero status indicates some sort of error.  In this
  * case, the status is a UNIX error number."  This can be problematic
  * if the server and client use different errno values for the same
  * error.
  *
  * However, the OpenGroup XNFS spec provides a simple mapping that is
  * independent of local errno values on the server and the client.
  */
 static int decode_status(struct xdr_stream *xdr, struct mountres *res)
 {
 	unsigned int i;
 	u32 status;
 	__be32 *p;

 	p = xdr_inline_decode(xdr, 4);
 	if (unlikely(p == NULL))
 		return -EIO;
 	status = be32_to_cpup(p);

 	for (i = 0; i < ARRAY_SIZE(mnt_errtbl); i++) {
 		if (mnt_errtbl[i].status == status) {
 			res->errno = mnt_errtbl[i].errno;
 			return 0;
 		}
 	}

 	dprintk("NFS: unrecognized MNT status code: %u\n", status);
 	res->errno = -EACCES;
 	return 0;
 }

 static int decode_fhandle(struct xdr_stream *xdr, struct mountres *res)
 {
 	struct nfs_fh *fh = res->fh;
 	__be32 *p;

 	p = xdr_inline_decode(xdr, NFS2_FHSIZE);
 	if (unlikely(p == NULL))
 		return -EIO;

 	fh->size = NFS2_FHSIZE;
 	memcpy(fh->data, p, NFS2_FHSIZE);
 	return 0;
 }

 static int mnt_xdr_dec_mountres(struct rpc_rqst *req,
 				struct xdr_stream *xdr,
 				void *data)
 {
 	struct mountres *res = data;
 	int status;

 	status = decode_status(xdr, res);
 	if (unlikely(status != 0 || res->errno != 0))
 		return status;
 	return decode_fhandle(xdr, res);
 }

 static int decode_fhs_status(struct xdr_stream *xdr, struct mountres *res)
 {
 	unsigned int i;
 	u32 status;
 	__be32 *p;

 	p = xdr_inline_decode(xdr, 4);
 	if (unlikely(p == NULL))
 		return -EIO;
 	status = be32_to_cpup(p);

 	for (i = 0; i < ARRAY_SIZE(mnt3_errtbl); i++) {
 		if (mnt3_errtbl[i].status == status) {
 			res->errno = mnt3_errtbl[i].errno;
 			return 0;
 		}
 	}

 	dprintk("NFS: unrecognized MNT3 status code: %u\n", status);
 	res->errno = -EACCES;
 	return 0;
 }

 static int decode_fhandle3(struct xdr_stream *xdr, struct mountres *res)
 {
 	struct nfs_fh *fh = res->fh;
 	u32 size;
 	__be32 *p;

 	p = xdr_inline_decode(xdr, 4);
 	if (unlikely(p == NULL))
 		return -EIO;

 	size = be32_to_cpup(p);
 	if (size > NFS3_FHSIZE || size == 0)
 		return -EIO;

 	p = xdr_inline_decode(xdr, size);
 	if (unlikely(p == NULL))
 		return -EIO;

 	fh->size = size;
 	memcpy(fh->data, p, size);
 	return 0;
 }

 static int decode_auth_flavors(struct xdr_stream *xdr, struct mountres *res)
 {
 	rpc_authflavor_t *flavors = res->auth_flavors;
 	unsigned int *count = res->auth_count;
 	u32 entries, i;
 	__be32 *p;

 	if (*count == 0)
 		return 0;

 	p = xdr_inline_decode(xdr, 4);
 	if (unlikely(p == NULL))
 		return -EIO;
 	entries = be32_to_cpup(p);
 	dprintk("NFS: received %u auth flavors\n", entries);
 	if (entries > NFS_MAX_SECFLAVORS)
 		entries = NFS_MAX_SECFLAVORS;

 	p = xdr_inline_decode(xdr, 4 * entries);
 	if (unlikely(p == NULL))
 		return -EIO;

 	if (entries > *count)
 		entries = *count;

 	for (i = 0; i < entries; i++) {
 		flavors[i] = be32_to_cpup(p++);
 		dprintk("NFS:   auth flavor[%u]: %d\n", i, flavors[i]);
 	}
 	*count = i;

 	return 0;
 }

 static int mnt_xdr_dec_mountres3(struct rpc_rqst *req,
 				 struct xdr_stream *xdr,
 				 void *data)
 {
 	struct mountres *res = data;
 	int status;

 	status = decode_fhs_status(xdr, res);
 	if (unlikely(status != 0 || res->errno != 0))
 		return status;
 	status = decode_fhandle3(xdr, res);
 	if (unlikely(status != 0)) {
 		res->errno = -EBADHANDLE;
 		return 0;
 	}
 	return decode_auth_flavors(xdr, res);
 }

 static const struct rpc_procinfo mnt_procedures[] = {
 	[MOUNTPROC_MNT] = {
 		.p_proc		= MOUNTPROC_MNT,
 		.p_encode	= mnt_xdr_enc_dirpath,
 		.p_decode	= mnt_xdr_dec_mountres,
 		.p_arglen	= MNT_enc_dirpath_sz,
 		.p_replen	= MNT_dec_mountres_sz,
 		.p_statidx	= MOUNTPROC_MNT,
 		.p_name		= "MOUNT",
 	},
 	[MOUNTPROC_UMNT] = {
 		.p_proc		= MOUNTPROC_UMNT,
 		.p_encode	= mnt_xdr_enc_dirpath,
 		.p_arglen	= MNT_enc_dirpath_sz,
 		.p_statidx	= MOUNTPROC_UMNT,
 		.p_name		= "UMOUNT",
 	},
 };

 static const struct rpc_procinfo mnt3_procedures[] = {
 	[MOUNTPROC3_MNT] = {
 		.p_proc		= MOUNTPROC3_MNT,
 		.p_encode	= mnt_xdr_enc_dirpath,
 		.p_decode	= mnt_xdr_dec_mountres3,
 		.p_arglen	= MNT_enc_dirpath_sz,
 		.p_replen	= MNT_dec_mountres3_sz,
 		.p_statidx	= MOUNTPROC3_MNT,
 		.p_name		= "MOUNT",
 	},
 	[MOUNTPROC3_UMNT] = {
 		.p_proc		= MOUNTPROC3_UMNT,
 		.p_encode	= mnt_xdr_enc_dirpath,
 		.p_arglen	= MNT_enc_dirpath_sz,
 		.p_statidx	= MOUNTPROC3_UMNT,
 		.p_name		= "UMOUNT",
 	},
 };

 static unsigned int mnt_counts[ARRAY_SIZE(mnt_procedures)];
 static const struct rpc_version mnt_version1 = {
 	.number		= 1,
 	.nrprocs	= ARRAY_SIZE(mnt_procedures),
 	.procs		= mnt_procedures,
 	.counts		= mnt_counts,
 };

 static unsigned int mnt3_counts[ARRAY_SIZE(mnt3_procedures)];
 static const struct rpc_version mnt_version3 = {
 	.number		= 3,
 	.nrprocs	= ARRAY_SIZE(mnt3_procedures),
 	.procs		= mnt3_procedures,
 	.counts		= mnt3_counts,
 };

 static const struct rpc_version *mnt_version[] = {
 	NULL,
 	&mnt_version1,
 	NULL,
 	&mnt_version3,
 };

 static struct rpc_stat mnt_stats;

 static const struct rpc_program mnt_program = {
 	.name		= "mount",
 	.number		= NFS_MNT_PROGRAM,
 	.nrvers		= ARRAY_SIZE(mnt_version),
 	.version	= mnt_version,
 	.stats		= &mnt_stats,
 };
	// SPDX-License-Identifier: GPL-2.0
	/*
	* In-kernel MOUNT protocol client
	*
	* Copyright (C) 1997, Olaf Kirch <okir@monad.swb.de>
	*/

	#include <linux/types.h>
	#include <linux/socket.h>
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/uio.h>
	#include <linux/net.h>
	#include <linux/in.h>
	#include <linux/sunrpc/clnt.h>
	#include <linux/sunrpc/sched.h>
	#include <linux/nfs_fs.h>
	#include "internal.h"

	#define NFSDBG_FACILITY NFSDBG_MOUNT

	/*
	* Defined by RFC 1094, section A.3; and RFC 1813, section 5.1.4
	*/
	#define MNTPATHLEN (1024)

	/*
	* XDR data type sizes
	*/
	#define encode_dirpath_sz (1 + XDR_QUADLEN(MNTPATHLEN))
	#define MNT_status_sz (1)
	#define MNT_fhandle_sz XDR_QUADLEN(NFS2_FHSIZE)
	#define MNT_fhandlev3_sz XDR_QUADLEN(NFS3_FHSIZE)
	#define MNT_authflav3_sz (1 + NFS_MAX_SECFLAVORS)

	/*
	* XDR argument and result sizes
	*/
	#define MNT_enc_dirpath_sz encode_dirpath_sz
	#define MNT_dec_mountres_sz (MNT_status_sz + MNT_fhandle_sz)
	#define MNT_dec_mountres3_sz (MNT_status_sz + MNT_fhandlev3_sz + \
	MNT_authflav3_sz)

	/*
	* Defined by RFC 1094, section A.5
	*/
	enum {
	MOUNTPROC_NULL = 0,
	MOUNTPROC_MNT = 1,
	MOUNTPROC_DUMP = 2,
	MOUNTPROC_UMNT = 3,
	MOUNTPROC_UMNTALL = 4,
	MOUNTPROC_EXPORT = 5,
	};

	/*
	* Defined by RFC 1813, section 5.2
	*/
	enum {
	MOUNTPROC3_NULL = 0,
	MOUNTPROC3_MNT = 1,
	MOUNTPROC3_DUMP = 2,
	MOUNTPROC3_UMNT = 3,
	MOUNTPROC3_UMNTALL = 4,
	MOUNTPROC3_EXPORT = 5,
	};

	static const struct rpc_program mnt_program;

	/*
	* Defined by OpenGroup XNFS Version 3W, chapter 8
	*/
	enum mountstat {
	MNT_OK = 0,
	MNT_EPERM = 1,
	MNT_ENOENT = 2,
	MNT_EACCES = 13,
	MNT_EINVAL = 22,
	};

	static struct {
	u32 status;
	int errno;
	} mnt_errtbl[] = {
	{ .status = MNT_OK, .errno = 0, },
	{ .status = MNT_EPERM, .errno = -EPERM, },
	{ .status = MNT_ENOENT, .errno = -ENOENT, },
	{ .status = MNT_EACCES, .errno = -EACCES, },
	{ .status = MNT_EINVAL, .errno = -EINVAL, },
	};

	/*
	* Defined by RFC 1813, section 5.1.5
	*/
	enum mountstat3 {
	MNT3_OK = 0, /* no error */
	MNT3ERR_PERM = 1, /* Not owner */
	MNT3ERR_NOENT = 2, /* No such file or directory */
	MNT3ERR_IO = 5, /* I/O error */
	MNT3ERR_ACCES = 13, /* Permission denied */
	MNT3ERR_NOTDIR = 20, /* Not a directory */
	MNT3ERR_INVAL = 22, /* Invalid argument */
	MNT3ERR_NAMETOOLONG = 63, /* Filename too long */
	MNT3ERR_NOTSUPP = 10004, /* Operation not supported */
	MNT3ERR_SERVERFAULT = 10006, /* A failure on the server */
	};

	static struct {
	u32 status;
	int errno;
	} mnt3_errtbl[] = {
	{ .status = MNT3_OK, .errno = 0, },
	{ .status = MNT3ERR_PERM, .errno = -EPERM, },
	{ .status = MNT3ERR_NOENT, .errno = -ENOENT, },
	{ .status = MNT3ERR_IO, .errno = -EIO, },
	{ .status = MNT3ERR_ACCES, .errno = -EACCES, },
	{ .status = MNT3ERR_NOTDIR, .errno = -ENOTDIR, },
	{ .status = MNT3ERR_INVAL, .errno = -EINVAL, },
	{ .status = MNT3ERR_NAMETOOLONG, .errno = -ENAMETOOLONG, },
	{ .status = MNT3ERR_NOTSUPP, .errno = -ENOTSUPP, },
	{ .status = MNT3ERR_SERVERFAULT, .errno = -EREMOTEIO, },
	};

	struct mountres {
	int errno;
	struct nfs_fh *fh;
	unsigned int *auth_count;
	rpc_authflavor_t *auth_flavors;
	};

	/**
	* nfs_mount - Obtain an NFS file handle for the given host and path
	* @info: pointer to mount request arguments
	* @timeo: deciseconds the mount waits for a response before it retries
	* @retrans: number of times the mount retries a request
	*
	* Uses timeout parameters specified by caller. On successful return, the
	* auth_flavs list and auth_flav_len will be populated with the list from the
	* server or a faked-up list if the server didn't provide one.
	*/
	int nfs_mount(struct nfs_mount_request *info, int timeo, int retrans)
	{
	struct rpc_timeout mnt_timeout;
	struct mountres result = {
	.fh = info->fh,
	.auth_count = info->auth_flav_len,
	.auth_flavors = info->auth_flavs,
	};
	struct rpc_message msg = {
	.rpc_argp = info->dirpath,
	.rpc_resp = &result,
	};
	struct rpc_create_args args = {
	.net = info->net,
	.protocol = info->protocol,
	.address = (struct sockaddr *)info->sap,
	.addrsize = info->salen,
	.timeout = &mnt_timeout,
	.servername = info->hostname,
	.program = &mnt_program,
	.version = info->version,
	.authflavor = RPC_AUTH_UNIX,
	.cred = current_cred(),
	};
	struct rpc_clnt *mnt_clnt;
	int status;

	dprintk("NFS: sending MNT request for %s:%s\n",
	(info->hostname ? info->hostname : "server"),
	info->dirpath);

	if (strlen(info->dirpath) > MNTPATHLEN)
	return -ENAMETOOLONG;

	if (info->noresvport)
	args.flags \|= RPC_CLNT_CREATE_NONPRIVPORT;

	nfs_init_timeout_values(&mnt_timeout, info->protocol, timeo, retrans);
	mnt_clnt = rpc_create(&args);
	if (IS_ERR(mnt_clnt))
	goto out_clnt_err;

	if (info->version == NFS_MNT3_VERSION)
	msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC3_MNT];
	else
	msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC_MNT];

	status = rpc_call_sync(mnt_clnt, &msg, RPC_TASK_SOFT\|RPC_TASK_TIMEOUT);
	rpc_shutdown_client(mnt_clnt);

	if (status < 0)
	goto out_call_err;
	if (result.errno != 0)
	goto out_mnt_err;

	dprintk("NFS: MNT request succeeded\n");
	status = 0;

	/*
	* If the server didn't provide a flavor list, allow the
	* client to try any flavor.
	*/
	if (info->version != NFS_MNT3_VERSION \|\| *info->auth_flav_len == 0) {
	dprintk("NFS: Faking up auth_flavs list\n");
	info->auth_flavs[0] = RPC_AUTH_NULL;
	*info->auth_flav_len = 1;
	}
	out:
	return status;

	out_clnt_err:
	status = PTR_ERR(mnt_clnt);
	dprintk("NFS: failed to create MNT RPC client, status=%d\n", status);
	goto out;

	out_call_err:
	dprintk("NFS: MNT request failed, status=%d\n", status);
	goto out;

	out_mnt_err:
	dprintk("NFS: MNT server returned result %d\n", result.errno);
	status = result.errno;
	goto out;
	}

	/**
	* nfs_umount - Notify a server that we have unmounted this export
	* @info: pointer to umount request arguments
	*
	* MOUNTPROC_UMNT is advisory, so we set a short timeout, and always
	* use UDP.
	*/
	void nfs_umount(const struct nfs_mount_request *info)
	{
	static const struct rpc_timeout nfs_umnt_timeout = {
	.to_initval = 1 * HZ,
	.to_maxval = 3 * HZ,
	.to_retries = 2,
	};
	struct rpc_create_args args = {
	.net = info->net,
	.protocol = IPPROTO_UDP,
	.address = (struct sockaddr *)info->sap,
	.addrsize = info->salen,
	.timeout = &nfs_umnt_timeout,
	.servername = info->hostname,
	.program = &mnt_program,
	.version = info->version,
	.authflavor = RPC_AUTH_UNIX,
	.flags = RPC_CLNT_CREATE_NOPING,
	.cred = current_cred(),
	};
	struct rpc_message msg = {
	.rpc_argp = info->dirpath,
	};
	struct rpc_clnt *clnt;
	int status;

	if (strlen(info->dirpath) > MNTPATHLEN)
	return;

	if (info->noresvport)
	args.flags \|= RPC_CLNT_CREATE_NONPRIVPORT;

	clnt = rpc_create(&args);
	if (IS_ERR(clnt))
	goto out_clnt_err;

	dprintk("NFS: sending UMNT request for %s:%s\n",
	(info->hostname ? info->hostname : "server"), info->dirpath);

	if (info->version == NFS_MNT3_VERSION)
	msg.rpc_proc = &clnt->cl_procinfo[MOUNTPROC3_UMNT];
	else
	msg.rpc_proc = &clnt->cl_procinfo[MOUNTPROC_UMNT];

	status = rpc_call_sync(clnt, &msg, 0);
	rpc_shutdown_client(clnt);

	if (unlikely(status < 0))
	goto out_call_err;

	return;

	out_clnt_err:
	dprintk("NFS: failed to create UMNT RPC client, status=%ld\n",
	PTR_ERR(clnt));
	return;

	out_call_err:
	dprintk("NFS: UMNT request failed, status=%d\n", status);
	}

	/*
	* XDR encode/decode functions for MOUNT
	*/

	static void encode_mntdirpath(struct xdr_stream xdr, const char pathname)
	{
	const u32 pathname_len = strlen(pathname);
	__be32 *p;

	p = xdr_reserve_space(xdr, 4 + pathname_len);
	xdr_encode_opaque(p, pathname, pathname_len);
	}

	static void mnt_xdr_enc_dirpath(struct rpc_rqst req, struct xdr_stream xdr,
	const void *dirpath)
	{
	encode_mntdirpath(xdr, dirpath);
	}

	/*
	* RFC 1094: "A non-zero status indicates some sort of error. In this
	* case, the status is a UNIX error number." This can be problematic
	* if the server and client use different errno values for the same
	* error.
	*
	* However, the OpenGroup XNFS spec provides a simple mapping that is
	* independent of local errno values on the server and the client.
	*/
	static int decode_status(struct xdr_stream xdr, struct mountres res)
	{
	unsigned int i;
	u32 status;
	__be32 *p;

	p = xdr_inline_decode(xdr, 4);
	if (unlikely(p == NULL))
	return -EIO;
	status = be32_to_cpup(p);

	for (i = 0; i < ARRAY_SIZE(mnt_errtbl); i++) {
	if (mnt_errtbl[i].status == status) {
	res->errno = mnt_errtbl[i].errno;
	return 0;
	}
	}

	dprintk("NFS: unrecognized MNT status code: %u\n", status);
	res->errno = -EACCES;
	return 0;
	}

	static int decode_fhandle(struct xdr_stream xdr, struct mountres res)
	{
	struct nfs_fh *fh = res->fh;
	__be32 *p;

	p = xdr_inline_decode(xdr, NFS2_FHSIZE);
	if (unlikely(p == NULL))
	return -EIO;

	fh->size = NFS2_FHSIZE;
	memcpy(fh->data, p, NFS2_FHSIZE);
	return 0;
	}

	static int mnt_xdr_dec_mountres(struct rpc_rqst *req,
	struct xdr_stream *xdr,
	void *data)
	{
	struct mountres *res = data;
	int status;

	status = decode_status(xdr, res);
	if (unlikely(status != 0 \|\| res->errno != 0))
	return status;
	return decode_fhandle(xdr, res);
	}

	static int decode_fhs_status(struct xdr_stream xdr, struct mountres res)
	{
	unsigned int i;
	u32 status;
	__be32 *p;

	p = xdr_inline_decode(xdr, 4);
	if (unlikely(p == NULL))
	return -EIO;
	status = be32_to_cpup(p);

	for (i = 0; i < ARRAY_SIZE(mnt3_errtbl); i++) {
	if (mnt3_errtbl[i].status == status) {
	res->errno = mnt3_errtbl[i].errno;
	return 0;
	}
	}

	dprintk("NFS: unrecognized MNT3 status code: %u\n", status);
	res->errno = -EACCES;
	return 0;
	}

	static int decode_fhandle3(struct xdr_stream xdr, struct mountres res)
	{
	struct nfs_fh *fh = res->fh;
	u32 size;
	__be32 *p;

	p = xdr_inline_decode(xdr, 4);
	if (unlikely(p == NULL))
	return -EIO;

	size = be32_to_cpup(p);
	if (size > NFS3_FHSIZE \|\| size == 0)
	return -EIO;

	p = xdr_inline_decode(xdr, size);
	if (unlikely(p == NULL))
	return -EIO;

	fh->size = size;
	memcpy(fh->data, p, size);
	return 0;
	}

	static int decode_auth_flavors(struct xdr_stream xdr, struct mountres res)
	{
	rpc_authflavor_t *flavors = res->auth_flavors;
	unsigned int *count = res->auth_count;
	u32 entries, i;
	__be32 *p;

	if (*count == 0)
	return 0;

	p = xdr_inline_decode(xdr, 4);
	if (unlikely(p == NULL))
	return -EIO;
	entries = be32_to_cpup(p);
	dprintk("NFS: received %u auth flavors\n", entries);
	if (entries > NFS_MAX_SECFLAVORS)
	entries = NFS_MAX_SECFLAVORS;

	p = xdr_inline_decode(xdr, 4 * entries);
	if (unlikely(p == NULL))
	return -EIO;

	if (entries > *count)
	entries = *count;

	for (i = 0; i < entries; i++) {
	flavors[i] = be32_to_cpup(p++);
	dprintk("NFS: auth flavor[%u]: %d\n", i, flavors[i]);
	}
	*count = i;

	return 0;
	}

	static int mnt_xdr_dec_mountres3(struct rpc_rqst *req,
	struct xdr_stream *xdr,
	void *data)
	{
	struct mountres *res = data;
	int status;

	status = decode_fhs_status(xdr, res);
	if (unlikely(status != 0 \|\| res->errno != 0))
	return status;
	status = decode_fhandle3(xdr, res);
	if (unlikely(status != 0)) {
	res->errno = -EBADHANDLE;
	return 0;
	}
	return decode_auth_flavors(xdr, res);
	}

	static const struct rpc_procinfo mnt_procedures[] = {
	[MOUNTPROC_MNT] = {
	.p_proc = MOUNTPROC_MNT,
	.p_encode = mnt_xdr_enc_dirpath,
	.p_decode = mnt_xdr_dec_mountres,
	.p_arglen = MNT_enc_dirpath_sz,
	.p_replen = MNT_dec_mountres_sz,
	.p_statidx = MOUNTPROC_MNT,
	.p_name = "MOUNT",
	},
	[MOUNTPROC_UMNT] = {
	.p_proc = MOUNTPROC_UMNT,
	.p_encode = mnt_xdr_enc_dirpath,
	.p_arglen = MNT_enc_dirpath_sz,
	.p_statidx = MOUNTPROC_UMNT,
	.p_name = "UMOUNT",
	},
	};

	static const struct rpc_procinfo mnt3_procedures[] = {
	[MOUNTPROC3_MNT] = {
	.p_proc = MOUNTPROC3_MNT,
	.p_encode = mnt_xdr_enc_dirpath,
	.p_decode = mnt_xdr_dec_mountres3,
	.p_arglen = MNT_enc_dirpath_sz,
	.p_replen = MNT_dec_mountres3_sz,
	.p_statidx = MOUNTPROC3_MNT,
	.p_name = "MOUNT",
	},
	[MOUNTPROC3_UMNT] = {
	.p_proc = MOUNTPROC3_UMNT,
	.p_encode = mnt_xdr_enc_dirpath,
	.p_arglen = MNT_enc_dirpath_sz,
	.p_statidx = MOUNTPROC3_UMNT,
	.p_name = "UMOUNT",
	},
	};

	static unsigned int mnt_counts[ARRAY_SIZE(mnt_procedures)];
	static const struct rpc_version mnt_version1 = {
	.number = 1,
	.nrprocs = ARRAY_SIZE(mnt_procedures),
	.procs = mnt_procedures,
	.counts = mnt_counts,
	};

	static unsigned int mnt3_counts[ARRAY_SIZE(mnt3_procedures)];
	static const struct rpc_version mnt_version3 = {
	.number = 3,
	.nrprocs = ARRAY_SIZE(mnt3_procedures),
	.procs = mnt3_procedures,
	.counts = mnt3_counts,
	};

	static const struct rpc_version *mnt_version[] = {
	NULL,
	&mnt_version1,
	NULL,
	&mnt_version3,
	};

	static struct rpc_stat mnt_stats;

	static const struct rpc_program mnt_program = {
	.name = "mount",
	.number = NFS_MNT_PROGRAM,
	.nrvers = ARRAY_SIZE(mnt_version),
	.version = mnt_version,
	.stats = &mnt_stats,
	};