[mirror_ubuntu-bionic-kernel.git] / fs / nfs / super.c

/*
 *  linux/fs/nfs/super.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  nfs superblock handling functions
 *
 *  Modularised by Alan Cox <Alan.Cox@linux.org>, while hacking some
 *  experimental NFS changes. Modularisation taken straight from SYS5 fs.
 *
 *  Change to nfs_read_super() to permit NFS mounts to multi-homed hosts.
 *  J.S.Peatfield@damtp.cam.ac.uk
 *
 *  Split from inode.c by David Howells <dhowells@redhat.com>
 *
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>

#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/metrics.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs4_mount.h>
#include <linux/lockd/bind.h>
#include <linux/smp_lock.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/nfs_idmap.h>
#include <linux/vfs.h>
#include <linux/inet.h>
#include <linux/nfs_xdr.h>

#include <asm/system.h>
#include <asm/uaccess.h>

#include "nfs4_fs.h"
#include "callback.h"
#include "delegation.h"
#include "iostat.h"
#include "internal.h"

#define NFSDBG_FACILITY         NFSDBG_VFS

/* Maximum number of readahead requests
 * FIXME: this should really be a sysctl so that users may tune it to suit
 *        their needs. People that do NFS over a slow network, might for
 *        instance want to reduce it to something closer to 1 for improved
 *        interactive response.
 */
#define NFS_MAX_READAHEAD       (RPC_DEF_SLOT_TABLE - 1)

/*
 * RPC cruft for NFS
 */
static struct rpc_version * nfs_version[] = {
        NULL,
        NULL,
        &nfs_version2,
#if defined(CONFIG_NFS_V3)
        &nfs_version3,
#elif defined(CONFIG_NFS_V4)
        NULL,
#endif
#if defined(CONFIG_NFS_V4)
        &nfs_version4,
#endif
};

static struct rpc_program nfs_program = {
        .name                   = "nfs",
        .number                 = NFS_PROGRAM,
        .nrvers                 = ARRAY_SIZE(nfs_version),
        .version                = nfs_version,
        .stats                  = &nfs_rpcstat,
        .pipe_dir_name          = "/nfs",
};

struct rpc_stat nfs_rpcstat = {
        .program                = &nfs_program
};


#ifdef CONFIG_NFS_V3_ACL
static struct rpc_stat          nfsacl_rpcstat = { &nfsacl_program };
static struct rpc_version *     nfsacl_version[] = {
        [3]                     = &nfsacl_version3,
};

struct rpc_program              nfsacl_program = {
        .name =                 "nfsacl",
        .number =               NFS_ACL_PROGRAM,
        .nrvers =               ARRAY_SIZE(nfsacl_version),
        .version =              nfsacl_version,
        .stats =                &nfsacl_rpcstat,
};
#endif  /* CONFIG_NFS_V3_ACL */

static void nfs_umount_begin(struct vfsmount *, int);
static int  nfs_statfs(struct dentry *, struct kstatfs *);
static int  nfs_show_options(struct seq_file *, struct vfsmount *);
static int  nfs_show_stats(struct seq_file *, struct vfsmount *);
static int nfs_get_sb(struct file_system_type *, int, const char *, void *, struct vfsmount *);
static int nfs_clone_nfs_sb(struct file_system_type *fs_type,
                int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static void nfs_kill_super(struct super_block *);

static struct file_system_type nfs_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "nfs",
        .get_sb         = nfs_get_sb,
        .kill_sb        = nfs_kill_super,
        .fs_flags       = FS_ODD_RENAME|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};

struct file_system_type clone_nfs_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "nfs",
        .get_sb         = nfs_clone_nfs_sb,
        .kill_sb        = nfs_kill_super,
        .fs_flags       = FS_ODD_RENAME|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};

static struct super_operations nfs_sops = {
        .alloc_inode    = nfs_alloc_inode,
        .destroy_inode  = nfs_destroy_inode,
        .write_inode    = nfs_write_inode,
        .statfs         = nfs_statfs,
        .clear_inode    = nfs_clear_inode,
        .umount_begin   = nfs_umount_begin,
        .show_options   = nfs_show_options,
        .show_stats     = nfs_show_stats,
};

#ifdef CONFIG_NFS_V4
static int nfs4_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static int nfs_clone_nfs4_sb(struct file_system_type *fs_type,
                int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static int nfs_referral_nfs4_sb(struct file_system_type *fs_type,
                int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static void nfs4_kill_super(struct super_block *sb);

static struct file_system_type nfs4_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "nfs4",
        .get_sb         = nfs4_get_sb,
        .kill_sb        = nfs4_kill_super,
        .fs_flags       = FS_ODD_RENAME|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};

struct file_system_type clone_nfs4_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "nfs4",
        .get_sb         = nfs_clone_nfs4_sb,
        .kill_sb        = nfs4_kill_super,
        .fs_flags       = FS_ODD_RENAME|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};

struct file_system_type nfs_referral_nfs4_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "nfs4",
        .get_sb         = nfs_referral_nfs4_sb,
        .kill_sb        = nfs4_kill_super,
        .fs_flags       = FS_ODD_RENAME|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};

static struct super_operations nfs4_sops = {
        .alloc_inode    = nfs_alloc_inode,
        .destroy_inode  = nfs_destroy_inode,
        .write_inode    = nfs_write_inode,
        .statfs         = nfs_statfs,
        .clear_inode    = nfs4_clear_inode,
        .umount_begin   = nfs_umount_begin,
        .show_options   = nfs_show_options,
        .show_stats     = nfs_show_stats,
};
#endif

static struct shrinker *acl_shrinker;

/*
 * Register the NFS filesystems
 */
int __init register_nfs_fs(void)
{
        int ret;

        ret = register_filesystem(&nfs_fs_type);
        if (ret < 0)
                goto error_0;

#ifdef CONFIG_NFS_V4
        ret = nfs_register_sysctl();
        if (ret < 0)
                goto error_1;
        ret = register_filesystem(&nfs4_fs_type);
        if (ret < 0)
                goto error_2;
#endif
        acl_shrinker = set_shrinker(DEFAULT_SEEKS, nfs_access_cache_shrinker);
        return 0;

#ifdef CONFIG_NFS_V4
error_2:
        nfs_unregister_sysctl();
error_1:
        unregister_filesystem(&nfs_fs_type);
#endif
error_0:
        return ret;
}

/*
 * Unregister the NFS filesystems
 */
void __exit unregister_nfs_fs(void)
{
        if (acl_shrinker != NULL)
                remove_shrinker(acl_shrinker);
#ifdef CONFIG_NFS_V4
        unregister_filesystem(&nfs4_fs_type);
        nfs_unregister_sysctl();
#endif
        unregister_filesystem(&nfs_fs_type);
}

/*
 * Deliver file system statistics to userspace
 */
static int nfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
        struct super_block *sb = dentry->d_sb;
        struct nfs_server *server = NFS_SB(sb);
        unsigned char blockbits;
        unsigned long blockres;
        struct nfs_fh *rootfh = NFS_FH(sb->s_root->d_inode);
        struct nfs_fattr fattr;
        struct nfs_fsstat res = {
                        .fattr = &fattr,
        };
        int error;

        lock_kernel();

        error = server->rpc_ops->statfs(server, rootfh, &res);
        buf->f_type = NFS_SUPER_MAGIC;
        if (error < 0)
                goto out_err;

        /*
         * Current versions of glibc do not correctly handle the
         * case where f_frsize != f_bsize.  Eventually we want to
         * report the value of wtmult in this field.
         */
        buf->f_frsize = sb->s_blocksize;

        /*
         * On most *nix systems, f_blocks, f_bfree, and f_bavail
         * are reported in units of f_frsize.  Linux hasn't had
         * an f_frsize field in its statfs struct until recently,
         * thus historically Linux's sys_statfs reports these
         * fields in units of f_bsize.
         */
        buf->f_bsize = sb->s_blocksize;
        blockbits = sb->s_blocksize_bits;
        blockres = (1 << blockbits) - 1;
        buf->f_blocks = (res.tbytes + blockres) >> blockbits;
        buf->f_bfree = (res.fbytes + blockres) >> blockbits;
        buf->f_bavail = (res.abytes + blockres) >> blockbits;

        buf->f_files = res.tfiles;
        buf->f_ffree = res.afiles;

        buf->f_namelen = server->namelen;
 out:
        unlock_kernel();
        return 0;

 out_err:
        dprintk("%s: statfs error = %d\n", __FUNCTION__, -error);
        buf->f_bsize = buf->f_blocks = buf->f_bfree = buf->f_bavail = -1;
        goto out;

}

/*
 * Map the security flavour number to a name
 */
static const char *nfs_pseudoflavour_to_name(rpc_authflavor_t flavour)
{
        static const struct {
                rpc_authflavor_t flavour;
                const char *str;
        } sec_flavours[] = {
                { RPC_AUTH_NULL, "null" },
                { RPC_AUTH_UNIX, "sys" },
                { RPC_AUTH_GSS_KRB5, "krb5" },
                { RPC_AUTH_GSS_KRB5I, "krb5i" },
                { RPC_AUTH_GSS_KRB5P, "krb5p" },
                { RPC_AUTH_GSS_LKEY, "lkey" },
                { RPC_AUTH_GSS_LKEYI, "lkeyi" },
                { RPC_AUTH_GSS_LKEYP, "lkeyp" },
                { RPC_AUTH_GSS_SPKM, "spkm" },
                { RPC_AUTH_GSS_SPKMI, "spkmi" },
                { RPC_AUTH_GSS_SPKMP, "spkmp" },
                { -1, "unknown" }
        };
        int i;

        for (i=0; sec_flavours[i].flavour != -1; i++) {
                if (sec_flavours[i].flavour == flavour)
                        break;
        }
        return sec_flavours[i].str;
}

/*
 * Describe the mount options in force on this server representation
 */
static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss, int showdefaults)
{
        static struct proc_nfs_info {
                int flag;
                char *str;
                char *nostr;
        } nfs_info[] = {
                { NFS_MOUNT_SOFT, ",soft", ",hard" },
                { NFS_MOUNT_INTR, ",intr", "" },
                { NFS_MOUNT_NOCTO, ",nocto", "" },
                { NFS_MOUNT_NOAC, ",noac", "" },
                { NFS_MOUNT_NONLM, ",nolock", "" },
                { NFS_MOUNT_NOACL, ",noacl", "" },
                { 0, NULL, NULL }
        };
        struct proc_nfs_info *nfs_infop;
        char buf[12];
        char *proto;

        seq_printf(m, ",vers=%d", nfss->rpc_ops->version);
        seq_printf(m, ",rsize=%d", nfss->rsize);
        seq_printf(m, ",wsize=%d", nfss->wsize);
        if (nfss->acregmin != 3*HZ || showdefaults)
                seq_printf(m, ",acregmin=%d", nfss->acregmin/HZ);
        if (nfss->acregmax != 60*HZ || showdefaults)
                seq_printf(m, ",acregmax=%d", nfss->acregmax/HZ);
        if (nfss->acdirmin != 30*HZ || showdefaults)
                seq_printf(m, ",acdirmin=%d", nfss->acdirmin/HZ);
        if (nfss->acdirmax != 60*HZ || showdefaults)
                seq_printf(m, ",acdirmax=%d", nfss->acdirmax/HZ);
        for (nfs_infop = nfs_info; nfs_infop->flag; nfs_infop++) {
                if (nfss->flags & nfs_infop->flag)
                        seq_puts(m, nfs_infop->str);
                else
                        seq_puts(m, nfs_infop->nostr);
        }
        switch (nfss->client->cl_xprt->prot) {
                case IPPROTO_TCP:
                        proto = "tcp";
                        break;
                case IPPROTO_UDP:
                        proto = "udp";
                        break;
                default:
                        snprintf(buf, sizeof(buf), "%u", nfss->client->cl_xprt->prot);
                        proto = buf;
        }
        seq_printf(m, ",proto=%s", proto);
        seq_printf(m, ",timeo=%lu", 10U * nfss->retrans_timeo / HZ);
        seq_printf(m, ",retrans=%u", nfss->retrans_count);
        seq_printf(m, ",sec=%s", nfs_pseudoflavour_to_name(nfss->client->cl_auth->au_flavor));
}

/*
 * Describe the mount options on this VFS mountpoint
 */
static int nfs_show_options(struct seq_file *m, struct vfsmount *mnt)
{
        struct nfs_server *nfss = NFS_SB(mnt->mnt_sb);

        nfs_show_mount_options(m, nfss, 0);

        seq_puts(m, ",addr=");
        seq_escape(m, nfss->hostname, " \t\n\\");

        return 0;
}

/*
 * Present statistical information for this VFS mountpoint
 */
static int nfs_show_stats(struct seq_file *m, struct vfsmount *mnt)
{
        int i, cpu;
        struct nfs_server *nfss = NFS_SB(mnt->mnt_sb);
        struct rpc_auth *auth = nfss->client->cl_auth;
        struct nfs_iostats totals = { };

        seq_printf(m, "statvers=%s", NFS_IOSTAT_VERS);

        /*
         * Display all mount option settings
         */
        seq_printf(m, "\n\topts:\t");
        seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? "ro" : "rw");
        seq_puts(m, mnt->mnt_sb->s_flags & MS_SYNCHRONOUS ? ",sync" : "");
        seq_puts(m, mnt->mnt_sb->s_flags & MS_NOATIME ? ",noatime" : "");
        seq_puts(m, mnt->mnt_sb->s_flags & MS_NODIRATIME ? ",nodiratime" : "");
        nfs_show_mount_options(m, nfss, 1);

        seq_printf(m, "\n\tage:\t%lu", (jiffies - nfss->mount_time) / HZ);

        seq_printf(m, "\n\tcaps:\t");
        seq_printf(m, "caps=0x%x", nfss->caps);
        seq_printf(m, ",wtmult=%d", nfss->wtmult);
        seq_printf(m, ",dtsize=%d", nfss->dtsize);
        seq_printf(m, ",bsize=%d", nfss->bsize);
        seq_printf(m, ",namelen=%d", nfss->namelen);

#ifdef CONFIG_NFS_V4
        if (nfss->rpc_ops->version == 4) {
                seq_printf(m, "\n\tnfsv4:\t");
                seq_printf(m, "bm0=0x%x", nfss->attr_bitmask[0]);
                seq_printf(m, ",bm1=0x%x", nfss->attr_bitmask[1]);
                seq_printf(m, ",acl=0x%x", nfss->acl_bitmask);
        }
#endif

        /*
         * Display security flavor in effect for this mount
         */
        seq_printf(m, "\n\tsec:\tflavor=%d", auth->au_ops->au_flavor);
        if (auth->au_flavor)
                seq_printf(m, ",pseudoflavor=%d", auth->au_flavor);

        /*
         * Display superblock I/O counters
         */
        for_each_possible_cpu(cpu) {
                struct nfs_iostats *stats;

                preempt_disable();
                stats = per_cpu_ptr(nfss->io_stats, cpu);

                for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
                        totals.events[i] += stats->events[i];
                for (i = 0; i < __NFSIOS_BYTESMAX; i++)
                        totals.bytes[i] += stats->bytes[i];

                preempt_enable();
        }

        seq_printf(m, "\n\tevents:\t");
        for (i = 0; i < __NFSIOS_COUNTSMAX; i++)
                seq_printf(m, "%lu ", totals.events[i]);
        seq_printf(m, "\n\tbytes:\t");
        for (i = 0; i < __NFSIOS_BYTESMAX; i++)
                seq_printf(m, "%Lu ", totals.bytes[i]);
        seq_printf(m, "\n");

        rpc_print_iostats(m, nfss->client);

        return 0;
}

/*
 * Begin unmount by attempting to remove all automounted mountpoints we added
 * in response to traversals
 */
static void nfs_umount_begin(struct vfsmount *vfsmnt, int flags)
{
        struct nfs_server *server;
        struct rpc_clnt *rpc;

        shrink_submounts(vfsmnt, &nfs_automount_list);
        if (!(flags & MNT_FORCE))
                return;
        /* -EIO all pending I/O */
        server = NFS_SB(vfsmnt->mnt_sb);
        rpc = server->client;
        if (!IS_ERR(rpc))
                rpc_killall_tasks(rpc);
        rpc = server->client_acl;
        if (!IS_ERR(rpc))
                rpc_killall_tasks(rpc);
}

/*
 * Obtain the root inode of the file system.
 */
static struct inode *
nfs_get_root(struct super_block *sb, struct nfs_fh *rootfh, struct nfs_fsinfo *fsinfo)
{
        struct nfs_server       *server = NFS_SB(sb);
        int                     error;

        error = server->rpc_ops->getroot(server, rootfh, fsinfo);
        if (error < 0) {
                dprintk("nfs_get_root: getattr error = %d\n", -error);
                return ERR_PTR(error);
        }

        server->fsid = fsinfo->fattr->fsid;
        return nfs_fhget(sb, rootfh, fsinfo->fattr);
}

/*
 * Do NFS version-independent mount processing, and sanity checking
 */
static int
nfs_sb_init(struct super_block *sb, rpc_authflavor_t authflavor)
{
        struct nfs_server       *server;
        struct inode            *root_inode;
        struct nfs_fattr        fattr;
        struct nfs_fsinfo       fsinfo = {
                                        .fattr = &fattr,
                                };
        struct nfs_pathconf pathinfo = {
                        .fattr = &fattr,
        };
        int no_root_error = 0;
        unsigned long max_rpc_payload;

        /* We probably want something more informative here */
        snprintf(sb->s_id, sizeof(sb->s_id), "%x:%x", MAJOR(sb->s_dev), MINOR(sb->s_dev));

        server = NFS_SB(sb);

        sb->s_magic      = NFS_SUPER_MAGIC;

        server->io_stats = nfs_alloc_iostats();
        if (server->io_stats == NULL)
                return -ENOMEM;

        root_inode = nfs_get_root(sb, &server->fh, &fsinfo);
        /* Did getting the root inode fail? */
        if (IS_ERR(root_inode)) {
                no_root_error = PTR_ERR(root_inode);
                goto out_no_root;
        }
        sb->s_root = d_alloc_root(root_inode);
        if (!sb->s_root) {
                no_root_error = -ENOMEM;
                goto out_no_root;
        }
        sb->s_root->d_op = server->rpc_ops->dentry_ops;

        /* mount time stamp, in seconds */
        server->mount_time = jiffies;

        /* Get some general file system info */
        if (server->namelen == 0 &&
            server->rpc_ops->pathconf(server, &server->fh, &pathinfo) >= 0)
                server->namelen = pathinfo.max_namelen;
        /* Work out a lot of parameters */
        if (server->rsize == 0)
                server->rsize = nfs_block_size(fsinfo.rtpref, NULL);
        if (server->wsize == 0)
                server->wsize = nfs_block_size(fsinfo.wtpref, NULL);

        if (fsinfo.rtmax >= 512 && server->rsize > fsinfo.rtmax)
                server->rsize = nfs_block_size(fsinfo.rtmax, NULL);
        if (fsinfo.wtmax >= 512 && server->wsize > fsinfo.wtmax)
                server->wsize = nfs_block_size(fsinfo.wtmax, NULL);

        max_rpc_payload = nfs_block_size(rpc_max_payload(server->client), NULL);
        if (server->rsize > max_rpc_payload)
                server->rsize = max_rpc_payload;
        if (server->rsize > NFS_MAX_FILE_IO_SIZE)
                server->rsize = NFS_MAX_FILE_IO_SIZE;
        server->rpages = (server->rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

        if (server->wsize > max_rpc_payload)
                server->wsize = max_rpc_payload;
        if (server->wsize > NFS_MAX_FILE_IO_SIZE)
                server->wsize = NFS_MAX_FILE_IO_SIZE;
        server->wpages = (server->wsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

        if (sb->s_blocksize == 0)
                sb->s_blocksize = nfs_block_bits(server->wsize,
                                                         &sb->s_blocksize_bits);
        server->wtmult = nfs_block_bits(fsinfo.wtmult, NULL);

        server->dtsize = nfs_block_size(fsinfo.dtpref, NULL);
        if (server->dtsize > PAGE_CACHE_SIZE)
                server->dtsize = PAGE_CACHE_SIZE;
        if (server->dtsize > server->rsize)
                server->dtsize = server->rsize;

        if (server->flags & NFS_MOUNT_NOAC) {
                server->acregmin = server->acregmax = 0;
                server->acdirmin = server->acdirmax = 0;
                sb->s_flags |= MS_SYNCHRONOUS;
        }
        server->backing_dev_info.ra_pages = server->rpages * NFS_MAX_READAHEAD;

        nfs_super_set_maxbytes(sb, fsinfo.maxfilesize);

        server->client->cl_intr = (server->flags & NFS_MOUNT_INTR) ? 1 : 0;
        server->client->cl_softrtry = (server->flags & NFS_MOUNT_SOFT) ? 1 : 0;

        /* We're airborne Set socket buffersize */
        rpc_setbufsize(server->client, server->wsize + 100, server->rsize + 100);
        return 0;
        /* Yargs. It didn't work out. */
out_no_root:
        dprintk("nfs_sb_init: get root inode failed: errno %d\n", -no_root_error);
        if (!IS_ERR(root_inode))
                iput(root_inode);
        return no_root_error;
}

/*
 * Initialise the timeout values for a connection
 */
static void nfs_init_timeout_values(struct rpc_timeout *to, int proto, unsigned int timeo, unsigned int retrans)
{
        to->to_initval = timeo * HZ / 10;
        to->to_retries = retrans;
        if (!to->to_retries)
                to->to_retries = 2;

        switch (proto) {
        case IPPROTO_TCP:
                if (!to->to_initval)
                        to->to_initval = 60 * HZ;
                if (to->to_initval > NFS_MAX_TCP_TIMEOUT)
                        to->to_initval = NFS_MAX_TCP_TIMEOUT;
                to->to_increment = to->to_initval;
                to->to_maxval = to->to_initval + (to->to_increment * to->to_retries);
                to->to_exponential = 0;
                break;
        case IPPROTO_UDP:
        default:
                if (!to->to_initval)
                        to->to_initval = 11 * HZ / 10;
                if (to->to_initval > NFS_MAX_UDP_TIMEOUT)
                        to->to_initval = NFS_MAX_UDP_TIMEOUT;
                to->to_maxval = NFS_MAX_UDP_TIMEOUT;
                to->to_exponential = 1;
                break;
        }
}

/*
 * Create an RPC client handle.
 */
static struct rpc_clnt *
nfs_create_client(struct nfs_server *server, const struct nfs_mount_data *data)
{
        struct rpc_timeout      timeparms;
        struct rpc_xprt         *xprt = NULL;
        struct rpc_clnt         *clnt = NULL;
        int                     proto = (data->flags & NFS_MOUNT_TCP) ? IPPROTO_TCP : IPPROTO_UDP;

        nfs_init_timeout_values(&timeparms, proto, data->timeo, data->retrans);

        server->retrans_timeo = timeparms.to_initval;
        server->retrans_count = timeparms.to_retries;

        /* create transport and client */
        xprt = xprt_create_proto(proto, &server->addr, &timeparms);
        if (IS_ERR(xprt)) {
                dprintk("%s: cannot create RPC transport. Error = %ld\n",
                                __FUNCTION__, PTR_ERR(xprt));
                return (struct rpc_clnt *)xprt;
        }
        clnt = rpc_create_client(xprt, server->hostname, &nfs_program,
                                 server->rpc_ops->version, data->pseudoflavor);
        if (IS_ERR(clnt)) {
                dprintk("%s: cannot create RPC client. Error = %ld\n",
                                __FUNCTION__, PTR_ERR(xprt));
                goto out_fail;
        }

        clnt->cl_intr     = 1;
        clnt->cl_softrtry = 1;

        return clnt;

out_fail:
        return clnt;
}

/*
 * Clone a server record
 */
static struct nfs_server *nfs_clone_server(struct super_block *sb, struct nfs_clone_mount *data)
{
        struct nfs_server *server = NFS_SB(sb);
        struct nfs_server *parent = NFS_SB(data->sb);
        struct inode *root_inode;
        struct nfs_fsinfo fsinfo;
        void *err = ERR_PTR(-ENOMEM);

        sb->s_op = data->sb->s_op;
        sb->s_blocksize = data->sb->s_blocksize;
        sb->s_blocksize_bits = data->sb->s_blocksize_bits;
        sb->s_maxbytes = data->sb->s_maxbytes;

        server->client_sys = server->client_acl = ERR_PTR(-EINVAL);
        server->io_stats = nfs_alloc_iostats();
        if (server->io_stats == NULL)
                goto out;

        server->client = rpc_clone_client(parent->client);
        if (IS_ERR((err = server->client)))
                goto out;

        if (!IS_ERR(parent->client_sys)) {
                server->client_sys = rpc_clone_client(parent->client_sys);
                if (IS_ERR((err = server->client_sys)))
                        goto out;
        }
        if (!IS_ERR(parent->client_acl)) {
                server->client_acl = rpc_clone_client(parent->client_acl);
                if (IS_ERR((err = server->client_acl)))
                        goto out;
        }
        root_inode = nfs_fhget(sb, data->fh, data->fattr);
        if (!root_inode)
                goto out;
        sb->s_root = d_alloc_root(root_inode);
        if (!sb->s_root)
                goto out_put_root;
        fsinfo.fattr = data->fattr;
        if (NFS_PROTO(root_inode)->fsinfo(server, data->fh, &fsinfo) == 0)
                nfs_super_set_maxbytes(sb, fsinfo.maxfilesize);
        sb->s_root->d_op = server->rpc_ops->dentry_ops;
        sb->s_flags |= MS_ACTIVE;
        return server;
out_put_root:
        iput(root_inode);
out:
        return err;
}

/*
 * Copy an existing superblock and attach revised data
 */
static int nfs_clone_generic_sb(struct nfs_clone_mount *data,
                struct super_block *(*fill_sb)(struct nfs_server *, struct nfs_clone_mount *),
                struct nfs_server *(*fill_server)(struct super_block *, struct nfs_clone_mount *),
                struct vfsmount *mnt)
{
        struct nfs_server *server;
        struct nfs_server *parent = NFS_SB(data->sb);
        struct super_block *sb = ERR_PTR(-EINVAL);
        char *hostname;
        int error = -ENOMEM;
        int len;

        server = kmalloc(sizeof(struct nfs_server), GFP_KERNEL);
        if (server == NULL)
                goto out_err;
        memcpy(server, parent, sizeof(*server));
        hostname = (data->hostname != NULL) ? data->hostname : parent->hostname;
        len = strlen(hostname) + 1;
        server->hostname = kmalloc(len, GFP_KERNEL);
        if (server->hostname == NULL)
                goto free_server;
        memcpy(server->hostname, hostname, len);
        error = rpciod_up();
        if (error != 0)
                goto free_hostname;

        sb = fill_sb(server, data);
        if (IS_ERR(sb)) {
                error = PTR_ERR(sb);
                goto kill_rpciod;
        }
                
        if (sb->s_root)
                goto out_rpciod_down;

        server = fill_server(sb, data);
        if (IS_ERR(server)) {
                error = PTR_ERR(server);
                goto out_deactivate;
        }
        return simple_set_mnt(mnt, sb);
out_deactivate:
        up_write(&sb->s_umount);
        deactivate_super(sb);
        return error;
out_rpciod_down:
        rpciod_down();
        kfree(server->hostname);
        kfree(server);
        return simple_set_mnt(mnt, sb);
kill_rpciod:
        rpciod_down();
free_hostname:
        kfree(server->hostname);
free_server:
        kfree(server);
out_err:
        return error;
}

/*
 * Set up an NFS2/3 superblock
 *
 * The way this works is that the mount process passes a structure
 * in the data argument which contains the server's IP address
 * and the root file handle obtained from the server's mount
 * daemon. We stash these away in the private superblock fields.
 */
static int
nfs_fill_super(struct super_block *sb, struct nfs_mount_data *data, int silent)
{
        struct nfs_server       *server;
        rpc_authflavor_t        authflavor;

        server           = NFS_SB(sb);
        sb->s_blocksize_bits = 0;
        sb->s_blocksize = 0;
        if (data->bsize)
                sb->s_blocksize = nfs_block_size(data->bsize, &sb->s_blocksize_bits);
        if (data->rsize)
                server->rsize = nfs_block_size(data->rsize, NULL);
        if (data->wsize)
                server->wsize = nfs_block_size(data->wsize, NULL);
        server->flags    = data->flags & NFS_MOUNT_FLAGMASK;

        server->acregmin = data->acregmin*HZ;
        server->acregmax = data->acregmax*HZ;
        server->acdirmin = data->acdirmin*HZ;
        server->acdirmax = data->acdirmax*HZ;

        /* Start lockd here, before we might error out */
        if (!(server->flags & NFS_MOUNT_NONLM))
                lockd_up();

        server->namelen  = data->namlen;
        server->hostname = kmalloc(strlen(data->hostname) + 1, GFP_KERNEL);
        if (!server->hostname)
                return -ENOMEM;
        strcpy(server->hostname, data->hostname);

        /* Check NFS protocol revision and initialize RPC op vector
         * and file handle pool. */
#ifdef CONFIG_NFS_V3
        if (server->flags & NFS_MOUNT_VER3) {
                server->rpc_ops = &nfs_v3_clientops;
                server->caps |= NFS_CAP_READDIRPLUS;
        } else {
                server->rpc_ops = &nfs_v2_clientops;
        }
#else
        server->rpc_ops = &nfs_v2_clientops;
#endif

        /* Fill in pseudoflavor for mount version < 5 */
        if (!(data->flags & NFS_MOUNT_SECFLAVOUR))
                data->pseudoflavor = RPC_AUTH_UNIX;
        authflavor = data->pseudoflavor;        /* save for sb_init() */
        /* XXX maybe we want to add a server->pseudoflavor field */

        /* Create RPC client handles */
        server->client = nfs_create_client(server, data);
        if (IS_ERR(server->client))
                return PTR_ERR(server->client);
        /* RFC 2623, sec 2.3.2 */
        if (authflavor != RPC_AUTH_UNIX) {
                struct rpc_auth *auth;

                server->client_sys = rpc_clone_client(server->client);
                if (IS_ERR(server->client_sys))
                        return PTR_ERR(server->client_sys);
                auth = rpcauth_create(RPC_AUTH_UNIX, server->client_sys);
                if (IS_ERR(auth))
                        return PTR_ERR(auth);
        } else {
                atomic_inc(&server->client->cl_count);
                server->client_sys = server->client;
        }
        if (server->flags & NFS_MOUNT_VER3) {
#ifdef CONFIG_NFS_V3_ACL
                if (!(server->flags & NFS_MOUNT_NOACL)) {
                        server->client_acl = rpc_bind_new_program(server->client, &nfsacl_program, 3);
                        /* No errors! Assume that Sun nfsacls are supported */
                        if (!IS_ERR(server->client_acl))
                                server->caps |= NFS_CAP_ACLS;
                }
#else
                server->flags &= ~NFS_MOUNT_NOACL;
#endif /* CONFIG_NFS_V3_ACL */
                /*
                 * The VFS shouldn't apply the umask to mode bits. We will
                 * do so ourselves when necessary.
                 */
                sb->s_flags |= MS_POSIXACL;
                if (server->namelen == 0 || server->namelen > NFS3_MAXNAMLEN)
                        server->namelen = NFS3_MAXNAMLEN;
                sb->s_time_gran = 1;
        } else {
                if (server->namelen == 0 || server->namelen > NFS2_MAXNAMLEN)
                        server->namelen = NFS2_MAXNAMLEN;
        }

        sb->s_op = &nfs_sops;
        return nfs_sb_init(sb, authflavor);
}

static int nfs_set_super(struct super_block *s, void *data)
{
        s->s_fs_info = data;
        return set_anon_super(s, data);
}

static int nfs_compare_super(struct super_block *sb, void *data)
{
        struct nfs_server *server = data;
        struct nfs_server *old = NFS_SB(sb);

        if (old->addr.sin_addr.s_addr != server->addr.sin_addr.s_addr)
                return 0;
        if (old->addr.sin_port != server->addr.sin_port)
                return 0;
        return !nfs_compare_fh(&old->fh, &server->fh);
}

static int nfs_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
{
        int error;
        struct nfs_server *server = NULL;
        struct super_block *s;
        struct nfs_fh *root;
        struct nfs_mount_data *data = raw_data;

        error = -EINVAL;
        if (data == NULL) {
                dprintk("%s: missing data argument\n", __FUNCTION__);
                goto out_err_noserver;
        }
        if (data->version <= 0 || data->version > NFS_MOUNT_VERSION) {
                dprintk("%s: bad mount version\n", __FUNCTION__);
                goto out_err_noserver;
        }
        switch (data->version) {
                case 1:
                        data->namlen = 0;
                case 2:
                        data->bsize  = 0;
                case 3:
                        if (data->flags & NFS_MOUNT_VER3) {
                                dprintk("%s: mount structure version %d does not support NFSv3\n",
                                                __FUNCTION__,
                                                data->version);
                                goto out_err_noserver;
                        }
                        data->root.size = NFS2_FHSIZE;
                        memcpy(data->root.data, data->old_root.data, NFS2_FHSIZE);
                case 4:
                        if (data->flags & NFS_MOUNT_SECFLAVOUR) {
                                dprintk("%s: mount structure version %d does not support strong security\n",
                                                __FUNCTION__,
                                                data->version);
                                goto out_err_noserver;
                        }
                case 5:
                        memset(data->context, 0, sizeof(data->context));
        }
#ifndef CONFIG_NFS_V3
        /* If NFSv3 is not compiled in, return -EPROTONOSUPPORT */
        error = -EPROTONOSUPPORT;
        if (data->flags & NFS_MOUNT_VER3) {
                dprintk("%s: NFSv3 not compiled into kernel\n", __FUNCTION__);
                goto out_err_noserver;
        }
#endif /* CONFIG_NFS_V3 */

        error = -ENOMEM;
        server = kzalloc(sizeof(struct nfs_server), GFP_KERNEL);
        if (!server)
                goto out_err_noserver;
        /* Zero out the NFS state stuff */
        init_nfsv4_state(server);
        server->client = server->client_sys = server->client_acl = ERR_PTR(-EINVAL);

        root = &server->fh;
        if (data->flags & NFS_MOUNT_VER3)
                root->size = data->root.size;
        else
                root->size = NFS2_FHSIZE;
        error = -EINVAL;
        if (root->size > sizeof(root->data)) {
                dprintk("%s: invalid root filehandle\n", __FUNCTION__);
                goto out_err;
        }
        memcpy(root->data, data->root.data, root->size);

        /* We now require that the mount process passes the remote address */
        memcpy(&server->addr, &data->addr, sizeof(server->addr));
        if (server->addr.sin_addr.s_addr == INADDR_ANY) {
                dprintk("%s: mount program didn't pass remote address!\n",
                                __FUNCTION__);
                goto out_err;
        }

        /* Fire up rpciod if not yet running */
        error = rpciod_up();
        if (error < 0) {
                dprintk("%s: couldn't start rpciod! Error = %d\n",
                                __FUNCTION__, error);
                goto out_err;
        }

        s = sget(fs_type, nfs_compare_super, nfs_set_super, server);
        if (IS_ERR(s)) {
                error = PTR_ERR(s);
                goto out_err_rpciod;
        }

        if (s->s_root)
                goto out_rpciod_down;

        s->s_flags = flags;

        error = nfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
        if (error) {
                up_write(&s->s_umount);
                deactivate_super(s);
                return error;
        }
        s->s_flags |= MS_ACTIVE;
        return simple_set_mnt(mnt, s);

out_rpciod_down:
        rpciod_down();
        kfree(server);
        return simple_set_mnt(mnt, s);

out_err_rpciod:
        rpciod_down();
out_err:
        kfree(server);
out_err_noserver:
        return error;
}

static void nfs_kill_super(struct super_block *s)
{
        struct nfs_server *server = NFS_SB(s);

        kill_anon_super(s);

        if (!IS_ERR(server->client))
                rpc_shutdown_client(server->client);
        if (!IS_ERR(server->client_sys))
                rpc_shutdown_client(server->client_sys);
        if (!IS_ERR(server->client_acl))
                rpc_shutdown_client(server->client_acl);

        if (!(server->flags & NFS_MOUNT_NONLM))
                lockd_down();   /* release rpc.lockd */

        rpciod_down();          /* release rpciod */

        nfs_free_iostats(server->io_stats);
        kfree(server->hostname);
        kfree(server);
        nfs_release_automount_timer();
}

static struct super_block *nfs_clone_sb(struct nfs_server *server, struct nfs_clone_mount *data)
{
        struct super_block *sb;

        server->fsid = data->fattr->fsid;
        nfs_copy_fh(&server->fh, data->fh);
        sb = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, server);
        if (!IS_ERR(sb) && sb->s_root == NULL && !(server->flags & NFS_MOUNT_NONLM))
                lockd_up();
        return sb;
}

static int nfs_clone_nfs_sb(struct file_system_type *fs_type,
                int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
{
        struct nfs_clone_mount *data = raw_data;
        return nfs_clone_generic_sb(data, nfs_clone_sb, nfs_clone_server, mnt);
}

#ifdef CONFIG_NFS_V4
static struct rpc_clnt *nfs4_create_client(struct nfs_server *server,
        struct rpc_timeout *timeparms, int proto, rpc_authflavor_t flavor)
{
        struct nfs4_client *clp;
        struct rpc_xprt *xprt = NULL;
        struct rpc_clnt *clnt = NULL;
        int err = -EIO;

        clp = nfs4_get_client(&server->addr.sin_addr);
        if (!clp) {
                dprintk("%s: failed to create NFS4 client.\n", __FUNCTION__);
                return ERR_PTR(err);
        }

        /* Now create transport and client */
        down_write(&clp->cl_sem);
        if (IS_ERR(clp->cl_rpcclient)) {
                xprt = xprt_create_proto(proto, &server->addr, timeparms);
                if (IS_ERR(xprt)) {
                        up_write(&clp->cl_sem);
                        err = PTR_ERR(xprt);
                        dprintk("%s: cannot create RPC transport. Error = %d\n",
                                        __FUNCTION__, err);
                        goto out_fail;
                }
                /* Bind to a reserved port! */
                xprt->resvport = 1;
                clnt = rpc_create_client(xprt, server->hostname, &nfs_program,
                                server->rpc_ops->version, flavor);
                if (IS_ERR(clnt)) {
                        up_write(&clp->cl_sem);
                        err = PTR_ERR(clnt);
                        dprintk("%s: cannot create RPC client. Error = %d\n",
                                        __FUNCTION__, err);
                        goto out_fail;
                }
                clnt->cl_intr     = 1;
                clnt->cl_softrtry = 1;
                clp->cl_rpcclient = clnt;
                memcpy(clp->cl_ipaddr, server->ip_addr, sizeof(clp->cl_ipaddr));
                nfs_idmap_new(clp);
        }
        list_add_tail(&server->nfs4_siblings, &clp->cl_superblocks);
        clnt = rpc_clone_client(clp->cl_rpcclient);
        if (!IS_ERR(clnt))
                server->nfs4_state = clp;
        up_write(&clp->cl_sem);
        clp = NULL;

        if (IS_ERR(clnt)) {
                dprintk("%s: cannot create RPC client. Error = %d\n",
                                __FUNCTION__, err);
                return clnt;
        }

        if (server->nfs4_state->cl_idmap == NULL) {
                dprintk("%s: failed to create idmapper.\n", __FUNCTION__);
                return ERR_PTR(-ENOMEM);
        }

        if (clnt->cl_auth->au_flavor != flavor) {
                struct rpc_auth *auth;

                auth = rpcauth_create(flavor, clnt);
                if (IS_ERR(auth)) {
                        dprintk("%s: couldn't create credcache!\n", __FUNCTION__);
                        return (struct rpc_clnt *)auth;
                }
        }
        return clnt;

 out_fail:
        if (clp)
                nfs4_put_client(clp);
        return ERR_PTR(err);
}

/*
 * Set up an NFS4 superblock
 */
static int nfs4_fill_super(struct super_block *sb, struct nfs4_mount_data *data, int silent)
{
        struct nfs_server *server;
        struct rpc_timeout timeparms;
        rpc_authflavor_t authflavour;
        int err = -EIO;

        sb->s_blocksize_bits = 0;
        sb->s_blocksize = 0;
        server = NFS_SB(sb);
        if (data->rsize != 0)
                server->rsize = nfs_block_size(data->rsize, NULL);
        if (data->wsize != 0)
                server->wsize = nfs_block_size(data->wsize, NULL);
        server->flags = data->flags & NFS_MOUNT_FLAGMASK;
        server->caps = NFS_CAP_ATOMIC_OPEN;

        server->acregmin = data->acregmin*HZ;
        server->acregmax = data->acregmax*HZ;
        server->acdirmin = data->acdirmin*HZ;
        server->acdirmax = data->acdirmax*HZ;

        server->rpc_ops = &nfs_v4_clientops;

        nfs_init_timeout_values(&timeparms, data->proto, data->timeo, data->retrans);

        server->retrans_timeo = timeparms.to_initval;
        server->retrans_count = timeparms.to_retries;

        /* Now create transport and client */
        authflavour = RPC_AUTH_UNIX;
        if (data->auth_flavourlen != 0) {
                if (data->auth_flavourlen != 1) {
                        dprintk("%s: Invalid number of RPC auth flavours %d.\n",
                                        __FUNCTION__, data->auth_flavourlen);
                        err = -EINVAL;
                        goto out_fail;
                }
                if (copy_from_user(&authflavour, data->auth_flavours, sizeof(authflavour))) {
                        err = -EFAULT;
                        goto out_fail;
                }
        }

        server->client = nfs4_create_client(server, &timeparms, data->proto, authflavour);
        if (IS_ERR(server->client)) {
                err = PTR_ERR(server->client);
                        dprintk("%s: cannot create RPC client. Error = %d\n",
                                        __FUNCTION__, err);
                        goto out_fail;
        }

        sb->s_time_gran = 1;

        sb->s_op = &nfs4_sops;
        err = nfs_sb_init(sb, authflavour);

 out_fail:
        return err;
}

static int nfs4_compare_super(struct super_block *sb, void *data)
{
        struct nfs_server *server = data;
        struct nfs_server *old = NFS_SB(sb);

        if (strcmp(server->hostname, old->hostname) != 0)
                return 0;
        if (strcmp(server->mnt_path, old->mnt_path) != 0)
                return 0;
        return 1;
}

static void *
nfs_copy_user_string(char *dst, struct nfs_string *src, int maxlen)
{
        void *p = NULL;

        if (!src->len)
                return ERR_PTR(-EINVAL);
        if (src->len < maxlen)
                maxlen = src->len;
        if (dst == NULL) {
                p = dst = kmalloc(maxlen + 1, GFP_KERNEL);
                if (p == NULL)
                        return ERR_PTR(-ENOMEM);
        }
        if (copy_from_user(dst, src->data, maxlen)) {
                kfree(p);
                return ERR_PTR(-EFAULT);
        }
        dst[maxlen] = '\0';
        return dst;
}

static int nfs4_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
{
        int error;
        struct nfs_server *server;
        struct super_block *s;
        struct nfs4_mount_data *data = raw_data;
        void *p;

        if (data == NULL) {
                dprintk("%s: missing data argument\n", __FUNCTION__);
                return -EINVAL;
        }
        if (data->version <= 0 || data->version > NFS4_MOUNT_VERSION) {
                dprintk("%s: bad mount version\n", __FUNCTION__);
                return -EINVAL;
        }

        server = kzalloc(sizeof(struct nfs_server), GFP_KERNEL);
        if (!server)
                return -ENOMEM;
        /* Zero out the NFS state stuff */
        init_nfsv4_state(server);
        server->client = server->client_sys = server->client_acl = ERR_PTR(-EINVAL);

        p = nfs_copy_user_string(NULL, &data->hostname, 256);
        if (IS_ERR(p))
                goto out_err;
        server->hostname = p;

        p = nfs_copy_user_string(NULL, &data->mnt_path, 1024);
        if (IS_ERR(p))
                goto out_err;
        server->mnt_path = p;

        p = nfs_copy_user_string(server->ip_addr, &data->client_addr,
                        sizeof(server->ip_addr) - 1);
        if (IS_ERR(p))
                goto out_err;

        /* We now require that the mount process passes the remote address */
        if (data->host_addrlen != sizeof(server->addr)) {
                error = -EINVAL;
                goto out_free;
        }
        if (copy_from_user(&server->addr, data->host_addr, sizeof(server->addr))) {
                error = -EFAULT;
                goto out_free;
        }
        if (server->addr.sin_family != AF_INET ||
            server->addr.sin_addr.s_addr == INADDR_ANY) {
                dprintk("%s: mount program didn't pass remote IP address!\n",
                                __FUNCTION__);
                error = -EINVAL;
                goto out_free;
        }

        /* Fire up rpciod if not yet running */
        error = rpciod_up();
        if (error < 0) {
                dprintk("%s: couldn't start rpciod! Error = %d\n",
                                __FUNCTION__, error);
                goto out_free;
        }

        s = sget(fs_type, nfs4_compare_super, nfs_set_super, server);
        if (IS_ERR(s)) {
                error = PTR_ERR(s);
                goto out_free;
        }

        if (s->s_root) {
                kfree(server->mnt_path);
                kfree(server->hostname);
                kfree(server);
                return simple_set_mnt(mnt, s);
        }

        s->s_flags = flags;

        error = nfs4_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
        if (error) {
                up_write(&s->s_umount);
                deactivate_super(s);
                return error;
        }
        s->s_flags |= MS_ACTIVE;
        return simple_set_mnt(mnt, s);
out_err:
        error = PTR_ERR(p);
out_free:
        kfree(server->mnt_path);
        kfree(server->hostname);
        kfree(server);
        return error;
}

static void nfs4_kill_super(struct super_block *sb)
{
        struct nfs_server *server = NFS_SB(sb);

        nfs_return_all_delegations(sb);
        kill_anon_super(sb);

        nfs4_renewd_prepare_shutdown(server);

        if (server->client != NULL && !IS_ERR(server->client))
                rpc_shutdown_client(server->client);

        destroy_nfsv4_state(server);

        rpciod_down();

        nfs_free_iostats(server->io_stats);
        kfree(server->hostname);
        kfree(server);
        nfs_release_automount_timer();
}

/*
 * Constructs the SERVER-side path
 */
static inline char *nfs4_dup_path(const struct dentry *dentry)
{
        char *page = (char *) __get_free_page(GFP_USER);
        char *path;

        path = nfs4_path(dentry, page, PAGE_SIZE);
        if (!IS_ERR(path)) {
                int len = PAGE_SIZE + page - path;
                char *tmp = path;

                path = kmalloc(len, GFP_KERNEL);
                if (path)
                        memcpy(path, tmp, len);
                else
                        path = ERR_PTR(-ENOMEM);
        }
        free_page((unsigned long)page);
        return path;
}

static struct super_block *nfs4_clone_sb(struct nfs_server *server, struct nfs_clone_mount *data)
{
        const struct dentry *dentry = data->dentry;
        struct nfs4_client *clp = server->nfs4_state;
        struct super_block *sb;

        server->fsid = data->fattr->fsid;
        nfs_copy_fh(&server->fh, data->fh);
        server->mnt_path = nfs4_dup_path(dentry);
        if (IS_ERR(server->mnt_path)) {
                sb = (struct super_block *)server->mnt_path;
                goto err;
        }
        sb = sget(&nfs4_fs_type, nfs4_compare_super, nfs_set_super, server);
        if (IS_ERR(sb) || sb->s_root)
                goto free_path;
        nfs4_server_capabilities(server, &server->fh);

        down_write(&clp->cl_sem);
        atomic_inc(&clp->cl_count);
        list_add_tail(&server->nfs4_siblings, &clp->cl_superblocks);
        up_write(&clp->cl_sem);
        return sb;
free_path:
        kfree(server->mnt_path);
err:
        server->mnt_path = NULL;
        return sb;
}

static int nfs_clone_nfs4_sb(struct file_system_type *fs_type,
                int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
{
        struct nfs_clone_mount *data = raw_data;
        return nfs_clone_generic_sb(data, nfs4_clone_sb, nfs_clone_server, mnt);
}

static struct super_block *nfs4_referral_sb(struct nfs_server *server, struct nfs_clone_mount *data)
{
        struct super_block *sb = ERR_PTR(-ENOMEM);
        int len;

        len = strlen(data->mnt_path) + 1;
        server->mnt_path = kmalloc(len, GFP_KERNEL);
        if (server->mnt_path == NULL)
                goto err;
        memcpy(server->mnt_path, data->mnt_path, len);
        memcpy(&server->addr, data->addr, sizeof(struct sockaddr_in));

        sb = sget(&nfs4_fs_type, nfs4_compare_super, nfs_set_super, server);
        if (IS_ERR(sb) || sb->s_root)
                goto free_path;
        return sb;
free_path:
        kfree(server->mnt_path);
err:
        server->mnt_path = NULL;
        return sb;
}

static struct nfs_server *nfs4_referral_server(struct super_block *sb, struct nfs_clone_mount *data)
{
        struct nfs_server *server = NFS_SB(sb);
        struct rpc_timeout timeparms;
        int proto, timeo, retrans;
        void *err;

        proto = IPPROTO_TCP;
        /* Since we are following a referral and there may be alternatives,
           set the timeouts and retries to low values */
        timeo = 2;
        retrans = 1;
        nfs_init_timeout_values(&timeparms, proto, timeo, retrans);

        server->client = nfs4_create_client(server, &timeparms, proto, data->authflavor);
        if (IS_ERR((err = server->client)))
                goto out_err;

        sb->s_time_gran = 1;
        sb->s_op = &nfs4_sops;
        err = ERR_PTR(nfs_sb_init(sb, data->authflavor));
        if (!IS_ERR(err))
                return server;
out_err:
        return (struct nfs_server *)err;
}

static int nfs_referral_nfs4_sb(struct file_system_type *fs_type,
                int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
{
        struct nfs_clone_mount *data = raw_data;
        return nfs_clone_generic_sb(data, nfs4_referral_sb, nfs4_referral_server, mnt);
}

#endif