[PATCH] VFS: Permit filesystem to override root dentry on mount

[linux-2.6] / fs / nfs / inode.c

/*
 *  linux/fs/nfs/inode.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  nfs inode and 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
 *
 */

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

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

#define NFSDBG_FACILITY         NFSDBG_VFS
#define NFS_PARANOIA 1

/* 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)

static void nfs_invalidate_inode(struct inode *);
static int nfs_update_inode(struct inode *, struct nfs_fattr *);

static struct inode *nfs_alloc_inode(struct super_block *sb);
static void nfs_destroy_inode(struct inode *);
static int nfs_write_inode(struct inode *,int);
static void nfs_delete_inode(struct inode *);
static void nfs_clear_inode(struct inode *);
static void nfs_umount_begin(struct super_block *);
static int  nfs_statfs(struct super_block *, struct kstatfs *);
static int  nfs_show_options(struct seq_file *, struct vfsmount *);
static int  nfs_show_stats(struct seq_file *, struct vfsmount *);
static void nfs_zap_acl_cache(struct inode *);

static struct rpc_program       nfs_program;

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

/*
 * RPC cruft for NFS
 */
static struct rpc_stat          nfs_rpcstat = {
        .program                = &nfs_program
};
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",
};

#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 inline unsigned long
nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
{
        return nfs_fileid_to_ino_t(fattr->fileid);
}

static int
nfs_write_inode(struct inode *inode, int sync)
{
        int flags = sync ? FLUSH_SYNC : 0;
        int ret;

        ret = nfs_commit_inode(inode, flags);
        if (ret < 0)
                return ret;
        return 0;
}

static void
nfs_delete_inode(struct inode * inode)
{
        dprintk("NFS: delete_inode(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);

        truncate_inode_pages(&inode->i_data, 0);

        nfs_wb_all(inode);
        /*
         * The following should never happen...
         */
        if (nfs_have_writebacks(inode)) {
                printk(KERN_ERR "nfs_delete_inode: inode %ld has pending RPC requests\n", inode->i_ino);
        }

        clear_inode(inode);
}

static void
nfs_clear_inode(struct inode *inode)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        struct rpc_cred *cred;

        nfs_wb_all(inode);
        BUG_ON (!list_empty(&nfsi->open_files));
        nfs_zap_acl_cache(inode);
        cred = nfsi->cache_access.cred;
        if (cred)
                put_rpccred(cred);
        BUG_ON(atomic_read(&nfsi->data_updates) != 0);
}

void
nfs_umount_begin(struct super_block *sb)
{
        struct rpc_clnt *rpc = NFS_SB(sb)->client;

        /* -EIO all pending I/O */
        if (!IS_ERR(rpc))
                rpc_killall_tasks(rpc);
        rpc = NFS_SB(sb)->client_acl;
        if (!IS_ERR(rpc))
                rpc_killall_tasks(rpc);
}


static inline unsigned long
nfs_block_bits(unsigned long bsize, unsigned char *nrbitsp)
{
        /* make sure blocksize is a power of two */
        if ((bsize & (bsize - 1)) || nrbitsp) {
                unsigned char   nrbits;

                for (nrbits = 31; nrbits && !(bsize & (1 << nrbits)); nrbits--)
                        ;
                bsize = 1 << nrbits;
                if (nrbitsp)
                        *nrbitsp = nrbits;
        }

        return bsize;
}

/*
 * Calculate the number of 512byte blocks used.
 */
static inline unsigned long
nfs_calc_block_size(u64 tsize)
{
        loff_t used = (tsize + 511) >> 9;
        return (used > ULONG_MAX) ? ULONG_MAX : used;
}

/*
 * Compute and set NFS server blocksize
 */
static inline unsigned long
nfs_block_size(unsigned long bsize, unsigned char *nrbitsp)
{
        if (bsize < NFS_MIN_FILE_IO_SIZE)
                bsize = NFS_DEF_FILE_IO_SIZE;
        else if (bsize >= NFS_MAX_FILE_IO_SIZE)
                bsize = NFS_MAX_FILE_IO_SIZE;

        return nfs_block_bits(bsize, nrbitsp);
}

/*
 * 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);
        }

        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;

        sb->s_maxbytes = fsinfo.maxfilesize;
        if (sb->s_maxbytes > MAX_LFS_FILESIZE) 
                sb->s_maxbytes = MAX_LFS_FILESIZE; 

        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;
}

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;
}

/*
 * 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_statfs(struct super_block *sb, struct kstatfs *buf)
{
        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;

}

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);
}

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;
}

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;
}

/**
 * nfs_sync_mapping - helper to flush all mmapped dirty data to disk
 */
int nfs_sync_mapping(struct address_space *mapping)
{
        int ret;

        if (mapping->nrpages == 0)
                return 0;
        unmap_mapping_range(mapping, 0, 0, 0);
        ret = filemap_write_and_wait(mapping);
        if (ret != 0)
                goto out;
        ret = nfs_wb_all(mapping->host);
out:
        return ret;
}

/*
 * Invalidate the local caches
 */
static void nfs_zap_caches_locked(struct inode *inode)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        int mode = inode->i_mode;

        nfs_inc_stats(inode, NFSIOS_ATTRINVALIDATE);

        NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
        NFS_ATTRTIMEO_UPDATE(inode) = jiffies;

        memset(NFS_COOKIEVERF(inode), 0, sizeof(NFS_COOKIEVERF(inode)));
        if (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL|NFS_INO_REVAL_PAGECACHE;
        else
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL|NFS_INO_REVAL_PAGECACHE;
}

void nfs_zap_caches(struct inode *inode)
{
        spin_lock(&inode->i_lock);
        nfs_zap_caches_locked(inode);
        spin_unlock(&inode->i_lock);
}

static void nfs_zap_acl_cache(struct inode *inode)
{
        void (*clear_acl_cache)(struct inode *);

        clear_acl_cache = NFS_PROTO(inode)->clear_acl_cache;
        if (clear_acl_cache != NULL)
                clear_acl_cache(inode);
        spin_lock(&inode->i_lock);
        NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_ACL;
        spin_unlock(&inode->i_lock);
}

/*
 * Invalidate, but do not unhash, the inode.
 * NB: must be called with inode->i_lock held!
 */
static void nfs_invalidate_inode(struct inode *inode)
{
        set_bit(NFS_INO_STALE, &NFS_FLAGS(inode));
        nfs_zap_caches_locked(inode);
}

struct nfs_find_desc {
        struct nfs_fh           *fh;
        struct nfs_fattr        *fattr;
};

/*
 * In NFSv3 we can have 64bit inode numbers. In order to support
 * this, and re-exported directories (also seen in NFSv2)
 * we are forced to allow 2 different inodes to have the same
 * i_ino.
 */
static int
nfs_find_actor(struct inode *inode, void *opaque)
{
        struct nfs_find_desc    *desc = (struct nfs_find_desc *)opaque;
        struct nfs_fh           *fh = desc->fh;
        struct nfs_fattr        *fattr = desc->fattr;

        if (NFS_FILEID(inode) != fattr->fileid)
                return 0;
        if (nfs_compare_fh(NFS_FH(inode), fh))
                return 0;
        if (is_bad_inode(inode) || NFS_STALE(inode))
                return 0;
        return 1;
}

static int
nfs_init_locked(struct inode *inode, void *opaque)
{
        struct nfs_find_desc    *desc = (struct nfs_find_desc *)opaque;
        struct nfs_fattr        *fattr = desc->fattr;

        NFS_FILEID(inode) = fattr->fileid;
        nfs_copy_fh(NFS_FH(inode), desc->fh);
        return 0;
}

/* Don't use READDIRPLUS on directories that we believe are too large */
#define NFS_LIMIT_READDIRPLUS (8*PAGE_SIZE)

/*
 * This is our front-end to iget that looks up inodes by file handle
 * instead of inode number.
 */
struct inode *
nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
{
        struct nfs_find_desc desc = {
                .fh     = fh,
                .fattr  = fattr
        };
        struct inode *inode = ERR_PTR(-ENOENT);
        unsigned long hash;

        if ((fattr->valid & NFS_ATTR_FATTR) == 0)
                goto out_no_inode;

        if (!fattr->nlink) {
                printk("NFS: Buggy server - nlink == 0!\n");
                goto out_no_inode;
        }

        hash = nfs_fattr_to_ino_t(fattr);

        inode = iget5_locked(sb, hash, nfs_find_actor, nfs_init_locked, &desc);
        if (inode == NULL) {
                inode = ERR_PTR(-ENOMEM);
                goto out_no_inode;
        }

        if (inode->i_state & I_NEW) {
                struct nfs_inode *nfsi = NFS_I(inode);

                /* We set i_ino for the few things that still rely on it,
                 * such as stat(2) */
                inode->i_ino = hash;

                /* We can't support update_atime(), since the server will reset it */
                inode->i_flags |= S_NOATIME|S_NOCMTIME;
                inode->i_mode = fattr->mode;
                /* Why so? Because we want revalidate for devices/FIFOs, and
                 * that's precisely what we have in nfs_file_inode_operations.
                 */
                inode->i_op = NFS_SB(sb)->rpc_ops->file_inode_ops;
                if (S_ISREG(inode->i_mode)) {
                        inode->i_fop = &nfs_file_operations;
                        inode->i_data.a_ops = &nfs_file_aops;
                        inode->i_data.backing_dev_info = &NFS_SB(sb)->backing_dev_info;
                } else if (S_ISDIR(inode->i_mode)) {
                        inode->i_op = NFS_SB(sb)->rpc_ops->dir_inode_ops;
                        inode->i_fop = &nfs_dir_operations;
                        if (nfs_server_capable(inode, NFS_CAP_READDIRPLUS)
                            && fattr->size <= NFS_LIMIT_READDIRPLUS)
                                set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_FLAGS(inode));
                } else if (S_ISLNK(inode->i_mode))
                        inode->i_op = &nfs_symlink_inode_operations;
                else
                        init_special_inode(inode, inode->i_mode, fattr->rdev);

                nfsi->read_cache_jiffies = fattr->time_start;
                nfsi->last_updated = jiffies;
                inode->i_atime = fattr->atime;
                inode->i_mtime = fattr->mtime;
                inode->i_ctime = fattr->ctime;
                if (fattr->valid & NFS_ATTR_FATTR_V4)
                        nfsi->change_attr = fattr->change_attr;
                inode->i_size = nfs_size_to_loff_t(fattr->size);
                inode->i_nlink = fattr->nlink;
                inode->i_uid = fattr->uid;
                inode->i_gid = fattr->gid;
                if (fattr->valid & (NFS_ATTR_FATTR_V3 | NFS_ATTR_FATTR_V4)) {
                        /*
                         * report the blocks in 512byte units
                         */
                        inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);
                        inode->i_blksize = inode->i_sb->s_blocksize;
                } else {
                        inode->i_blocks = fattr->du.nfs2.blocks;
                        inode->i_blksize = fattr->du.nfs2.blocksize;
                }
                nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
                nfsi->attrtimeo_timestamp = jiffies;
                memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
                nfsi->cache_access.cred = NULL;

                unlock_new_inode(inode);
        } else
                nfs_refresh_inode(inode, fattr);
        dprintk("NFS: nfs_fhget(%s/%Ld ct=%d)\n",
                inode->i_sb->s_id,
                (long long)NFS_FILEID(inode),
                atomic_read(&inode->i_count));

out:
        return inode;

out_no_inode:
        dprintk("nfs_fhget: iget failed with error %ld\n", PTR_ERR(inode));
        goto out;
}

#define NFS_VALID_ATTRS (ATTR_MODE|ATTR_UID|ATTR_GID|ATTR_SIZE|ATTR_ATIME|ATTR_ATIME_SET|ATTR_MTIME|ATTR_MTIME_SET)

int
nfs_setattr(struct dentry *dentry, struct iattr *attr)
{
        struct inode *inode = dentry->d_inode;
        struct nfs_fattr fattr;
        int error;

        nfs_inc_stats(inode, NFSIOS_VFSSETATTR);

        if (attr->ia_valid & ATTR_SIZE) {
                if (!S_ISREG(inode->i_mode) || attr->ia_size == i_size_read(inode))
                        attr->ia_valid &= ~ATTR_SIZE;
        }

        /* Optimization: if the end result is no change, don't RPC */
        attr->ia_valid &= NFS_VALID_ATTRS;
        if (attr->ia_valid == 0)
                return 0;

        lock_kernel();
        nfs_begin_data_update(inode);
        /* Write all dirty data */
        filemap_write_and_wait(inode->i_mapping);
        nfs_wb_all(inode);
        /*
         * Return any delegations if we're going to change ACLs
         */
        if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0)
                nfs_inode_return_delegation(inode);
        error = NFS_PROTO(inode)->setattr(dentry, &fattr, attr);
        if (error == 0)
                nfs_refresh_inode(inode, &fattr);
        nfs_end_data_update(inode);
        unlock_kernel();
        return error;
}

/**
 * nfs_setattr_update_inode - Update inode metadata after a setattr call.
 * @inode: pointer to struct inode
 * @attr: pointer to struct iattr
 *
 * Note: we do this in the *proc.c in order to ensure that
 *       it works for things like exclusive creates too.
 */
void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr)
{
        if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0) {
                if ((attr->ia_valid & ATTR_MODE) != 0) {
                        int mode = attr->ia_mode & S_IALLUGO;
                        mode |= inode->i_mode & ~S_IALLUGO;
                        inode->i_mode = mode;
                }
                if ((attr->ia_valid & ATTR_UID) != 0)
                        inode->i_uid = attr->ia_uid;
                if ((attr->ia_valid & ATTR_GID) != 0)
                        inode->i_gid = attr->ia_gid;
                spin_lock(&inode->i_lock);
                NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                spin_unlock(&inode->i_lock);
        }
        if ((attr->ia_valid & ATTR_SIZE) != 0) {
                nfs_inc_stats(inode, NFSIOS_SETATTRTRUNC);
                inode->i_size = attr->ia_size;
                vmtruncate(inode, attr->ia_size);
        }
}

static int nfs_wait_schedule(void *word)
{
        if (signal_pending(current))
                return -ERESTARTSYS;
        schedule();
        return 0;
}

/*
 * Wait for the inode to get unlocked.
 */
static int nfs_wait_on_inode(struct inode *inode)
{
        struct rpc_clnt *clnt = NFS_CLIENT(inode);
        struct nfs_inode *nfsi = NFS_I(inode);
        sigset_t oldmask;
        int error;

        rpc_clnt_sigmask(clnt, &oldmask);
        error = wait_on_bit_lock(&nfsi->flags, NFS_INO_REVALIDATING,
                                        nfs_wait_schedule, TASK_INTERRUPTIBLE);
        rpc_clnt_sigunmask(clnt, &oldmask);

        return error;
}

static void nfs_wake_up_inode(struct inode *inode)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        clear_bit(NFS_INO_REVALIDATING, &nfsi->flags);
        smp_mb__after_clear_bit();
        wake_up_bit(&nfsi->flags, NFS_INO_REVALIDATING);
}

int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
        struct inode *inode = dentry->d_inode;
        int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME;
        int err;

        /* Flush out writes to the server in order to update c/mtime */
        nfs_sync_inode_wait(inode, 0, 0, FLUSH_NOCOMMIT);

        /*
         * We may force a getattr if the user cares about atime.
         *
         * Note that we only have to check the vfsmount flags here:
         *  - NFS always sets S_NOATIME by so checking it would give a
         *    bogus result
         *  - NFS never sets MS_NOATIME or MS_NODIRATIME so there is
         *    no point in checking those.
         */
        if ((mnt->mnt_flags & MNT_NOATIME) ||
            ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)))
                need_atime = 0;

        if (need_atime)
                err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
        else
                err = nfs_revalidate_inode(NFS_SERVER(inode), inode);
        if (!err)
                generic_fillattr(inode, stat);
        return err;
}

static struct nfs_open_context *alloc_nfs_open_context(struct vfsmount *mnt, struct dentry *dentry, struct rpc_cred *cred)
{
        struct nfs_open_context *ctx;

        ctx = (struct nfs_open_context *)kmalloc(sizeof(*ctx), GFP_KERNEL);
        if (ctx != NULL) {
                atomic_set(&ctx->count, 1);
                ctx->dentry = dget(dentry);
                ctx->vfsmnt = mntget(mnt);
                ctx->cred = get_rpccred(cred);
                ctx->state = NULL;
                ctx->lockowner = current->files;
                ctx->error = 0;
                ctx->dir_cookie = 0;
        }
        return ctx;
}

struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx)
{
        if (ctx != NULL)
                atomic_inc(&ctx->count);
        return ctx;
}

void put_nfs_open_context(struct nfs_open_context *ctx)
{
        if (atomic_dec_and_test(&ctx->count)) {
                if (!list_empty(&ctx->list)) {
                        struct inode *inode = ctx->dentry->d_inode;
                        spin_lock(&inode->i_lock);
                        list_del(&ctx->list);
                        spin_unlock(&inode->i_lock);
                }
                if (ctx->state != NULL)
                        nfs4_close_state(ctx->state, ctx->mode);
                if (ctx->cred != NULL)
                        put_rpccred(ctx->cred);
                dput(ctx->dentry);
                mntput(ctx->vfsmnt);
                kfree(ctx);
        }
}

/*
 * Ensure that mmap has a recent RPC credential for use when writing out
 * shared pages
 */
static void nfs_file_set_open_context(struct file *filp, struct nfs_open_context *ctx)
{
        struct inode *inode = filp->f_dentry->d_inode;
        struct nfs_inode *nfsi = NFS_I(inode);

        filp->private_data = get_nfs_open_context(ctx);
        spin_lock(&inode->i_lock);
        list_add(&ctx->list, &nfsi->open_files);
        spin_unlock(&inode->i_lock);
}

/*
 * Given an inode, search for an open context with the desired characteristics
 */
struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_cred *cred, int mode)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        struct nfs_open_context *pos, *ctx = NULL;

        spin_lock(&inode->i_lock);
        list_for_each_entry(pos, &nfsi->open_files, list) {
                if (cred != NULL && pos->cred != cred)
                        continue;
                if ((pos->mode & mode) == mode) {
                        ctx = get_nfs_open_context(pos);
                        break;
                }
        }
        spin_unlock(&inode->i_lock);
        return ctx;
}

static void nfs_file_clear_open_context(struct file *filp)
{
        struct inode *inode = filp->f_dentry->d_inode;
        struct nfs_open_context *ctx = (struct nfs_open_context *)filp->private_data;

        if (ctx) {
                filp->private_data = NULL;
                spin_lock(&inode->i_lock);
                list_move_tail(&ctx->list, &NFS_I(inode)->open_files);
                spin_unlock(&inode->i_lock);
                put_nfs_open_context(ctx);
        }
}

/*
 * These allocate and release file read/write context information.
 */
int nfs_open(struct inode *inode, struct file *filp)
{
        struct nfs_open_context *ctx;
        struct rpc_cred *cred;

        cred = rpcauth_lookupcred(NFS_CLIENT(inode)->cl_auth, 0);
        if (IS_ERR(cred))
                return PTR_ERR(cred);
        ctx = alloc_nfs_open_context(filp->f_vfsmnt, filp->f_dentry, cred);
        put_rpccred(cred);
        if (ctx == NULL)
                return -ENOMEM;
        ctx->mode = filp->f_mode;
        nfs_file_set_open_context(filp, ctx);
        put_nfs_open_context(ctx);
        return 0;
}

int nfs_release(struct inode *inode, struct file *filp)
{
        nfs_file_clear_open_context(filp);
        return 0;
}

/*
 * This function is called whenever some part of NFS notices that
 * the cached attributes have to be refreshed.
 */
int
__nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
{
        int              status = -ESTALE;
        struct nfs_fattr fattr;
        struct nfs_inode *nfsi = NFS_I(inode);

        dfprintk(PAGECACHE, "NFS: revalidating (%s/%Ld)\n",
                inode->i_sb->s_id, (long long)NFS_FILEID(inode));

        lock_kernel();
        if (!inode || is_bad_inode(inode))
                goto out_nowait;
        if (NFS_STALE(inode))
                goto out_nowait;

        status = nfs_wait_on_inode(inode);
        if (status < 0)
                goto out;
        if (NFS_STALE(inode)) {
                status = -ESTALE;
                /* Do we trust the cached ESTALE? */
                if (NFS_ATTRTIMEO(inode) != 0) {
                        if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ATIME)) {
                                /* no */
                        } else
                                goto out;
                }
        }

        status = NFS_PROTO(inode)->getattr(server, NFS_FH(inode), &fattr);
        if (status != 0) {
                dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) getattr failed, error=%d\n",
                         inode->i_sb->s_id,
                         (long long)NFS_FILEID(inode), status);
                if (status == -ESTALE) {
                        nfs_zap_caches(inode);
                        if (!S_ISDIR(inode->i_mode))
                                set_bit(NFS_INO_STALE, &NFS_FLAGS(inode));
                }
                goto out;
        }

        spin_lock(&inode->i_lock);
        status = nfs_update_inode(inode, &fattr);
        if (status) {
                spin_unlock(&inode->i_lock);
                dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) refresh failed, error=%d\n",
                         inode->i_sb->s_id,
                         (long long)NFS_FILEID(inode), status);
                goto out;
        }
        spin_unlock(&inode->i_lock);

        nfs_revalidate_mapping(inode, inode->i_mapping);

        if (nfsi->cache_validity & NFS_INO_INVALID_ACL)
                nfs_zap_acl_cache(inode);

        dfprintk(PAGECACHE, "NFS: (%s/%Ld) revalidation complete\n",
                inode->i_sb->s_id,
                (long long)NFS_FILEID(inode));

 out:
        nfs_wake_up_inode(inode);

 out_nowait:
        unlock_kernel();
        return status;
}

int nfs_attribute_timeout(struct inode *inode)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        if (nfs_have_delegation(inode, FMODE_READ))
                return 0;
        return time_after(jiffies, nfsi->read_cache_jiffies+nfsi->attrtimeo);
}

/**
 * nfs_revalidate_inode - Revalidate the inode attributes
 * @server - pointer to nfs_server struct
 * @inode - pointer to inode struct
 *
 * Updates inode attribute information by retrieving the data from the server.
 */
int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
{
        nfs_inc_stats(inode, NFSIOS_INODEREVALIDATE);
        if (!(NFS_I(inode)->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
                        && !nfs_attribute_timeout(inode))
                return NFS_STALE(inode) ? -ESTALE : 0;
        return __nfs_revalidate_inode(server, inode);
}

/**
 * nfs_revalidate_mapping - Revalidate the pagecache
 * @inode - pointer to host inode
 * @mapping - pointer to mapping
 */
void nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        if (nfsi->cache_validity & NFS_INO_INVALID_DATA) {
                nfs_inc_stats(inode, NFSIOS_DATAINVALIDATE);
                if (S_ISREG(inode->i_mode))
                        nfs_sync_mapping(mapping);
                invalidate_inode_pages2(mapping);

                spin_lock(&inode->i_lock);
                nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;
                if (S_ISDIR(inode->i_mode)) {
                        memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
                        /* This ensures we revalidate child dentries */
                        nfsi->cache_change_attribute = jiffies;
                }
                spin_unlock(&inode->i_lock);

                dfprintk(PAGECACHE, "NFS: (%s/%Ld) data cache invalidated\n",
                                inode->i_sb->s_id,
                                (long long)NFS_FILEID(inode));
        }
}

/**
 * nfs_begin_data_update
 * @inode - pointer to inode
 * Declare that a set of operations will update file data on the server
 */
void nfs_begin_data_update(struct inode *inode)
{
        atomic_inc(&NFS_I(inode)->data_updates);
}

/**
 * nfs_end_data_update
 * @inode - pointer to inode
 * Declare end of the operations that will update file data
 * This will mark the inode as immediately needing revalidation
 * of its attribute cache.
 */
void nfs_end_data_update(struct inode *inode)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        if (!nfs_have_delegation(inode, FMODE_READ)) {
                /* Directories and symlinks: invalidate page cache */
                if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) {
                        spin_lock(&inode->i_lock);
                        nfsi->cache_validity |= NFS_INO_INVALID_DATA;
                        spin_unlock(&inode->i_lock);
                }
        }
        nfsi->cache_change_attribute = jiffies;
        atomic_dec(&nfsi->data_updates);
}

static void nfs_wcc_update_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        if ((fattr->valid & NFS_ATTR_PRE_CHANGE) != 0
                        && nfsi->change_attr == fattr->pre_change_attr) {
                nfsi->change_attr = fattr->change_attr;
                nfsi->cache_change_attribute = jiffies;
        }

        /* If we have atomic WCC data, we may update some attributes */
        if ((fattr->valid & NFS_ATTR_WCC) != 0) {
                if (timespec_equal(&inode->i_ctime, &fattr->pre_ctime)) {
                        memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
                        nfsi->cache_change_attribute = jiffies;
                }
                if (timespec_equal(&inode->i_mtime, &fattr->pre_mtime)) {
                        memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
                        nfsi->cache_change_attribute = jiffies;
                }
                if (inode->i_size == fattr->pre_size && nfsi->npages == 0) {
                        inode->i_size = fattr->size;
                        nfsi->cache_change_attribute = jiffies;
                }
        }
}

/**
 * nfs_check_inode_attributes - verify consistency of the inode attribute cache
 * @inode - pointer to inode
 * @fattr - updated attributes
 *
 * Verifies the attribute cache. If we have just changed the attributes,
 * so that fattr carries weak cache consistency data, then it may
 * also update the ctime/mtime/change_attribute.
 */
static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        loff_t cur_size, new_isize;
        int data_unstable;


        if ((fattr->valid & NFS_ATTR_FATTR) == 0)
                return 0;

        /* Has the inode gone and changed behind our back? */
        if (nfsi->fileid != fattr->fileid
                        || (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT)) {
                return -EIO;
        }

        /* Are we in the process of updating data on the server? */
        data_unstable = nfs_caches_unstable(inode);

        /* Do atomic weak cache consistency updates */
        nfs_wcc_update_inode(inode, fattr);

        if ((fattr->valid & NFS_ATTR_FATTR_V4) != 0) {
                if (nfsi->change_attr == fattr->change_attr)
                        goto out;
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (!data_unstable)
                        nfsi->cache_validity |= NFS_INO_REVAL_PAGECACHE;
        }

        /* Verify a few of the more important attributes */
        if (!timespec_equal(&inode->i_mtime, &fattr->mtime)) {
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (!data_unstable)
                        nfsi->cache_validity |= NFS_INO_REVAL_PAGECACHE;
        }

        cur_size = i_size_read(inode);
        new_isize = nfs_size_to_loff_t(fattr->size);
        if (cur_size != new_isize && nfsi->npages == 0)
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;

        /* Have any file permissions changed? */
        if ((inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO)
                        || inode->i_uid != fattr->uid
                        || inode->i_gid != fattr->gid)
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;

        /* Has the link count changed? */
        if (inode->i_nlink != fattr->nlink)
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR;

out:
        if (!timespec_equal(&inode->i_atime, &fattr->atime))
                nfsi->cache_validity |= NFS_INO_INVALID_ATIME;

        nfsi->read_cache_jiffies = fattr->time_start;
        return 0;
}

/**
 * nfs_refresh_inode - try to update the inode attribute cache
 * @inode - pointer to inode
 * @fattr - updated attributes
 *
 * Check that an RPC call that returned attributes has not overlapped with
 * other recent updates of the inode metadata, then decide whether it is
 * safe to do a full update of the inode attributes, or whether just to
 * call nfs_check_inode_attributes.
 */
int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        int status;

        if ((fattr->valid & NFS_ATTR_FATTR) == 0)
                return 0;
        spin_lock(&inode->i_lock);
        nfsi->cache_validity &= ~NFS_INO_REVAL_PAGECACHE;
        if (time_after(fattr->time_start, nfsi->last_updated))
                status = nfs_update_inode(inode, fattr);
        else
                status = nfs_check_inode_attributes(inode, fattr);

        spin_unlock(&inode->i_lock);
        return status;
}

/**
 * nfs_post_op_update_inode - try to update the inode attribute cache
 * @inode - pointer to inode
 * @fattr - updated attributes
 *
 * After an operation that has changed the inode metadata, mark the
 * attribute cache as being invalid, then try to update it.
 */
int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        int status = 0;

        spin_lock(&inode->i_lock);
        if (unlikely((fattr->valid & NFS_ATTR_FATTR) == 0)) {
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS;
                goto out;
        }
        status = nfs_update_inode(inode, fattr);
out:
        spin_unlock(&inode->i_lock);
        return status;
}

/*
 * Many nfs protocol calls return the new file attributes after
 * an operation.  Here we update the inode to reflect the state
 * of the server's inode.
 *
 * This is a bit tricky because we have to make sure all dirty pages
 * have been sent off to the server before calling invalidate_inode_pages.
 * To make sure no other process adds more write requests while we try
 * our best to flush them, we make them sleep during the attribute refresh.
 *
 * A very similar scenario holds for the dir cache.
 */
static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        loff_t cur_isize, new_isize;
        unsigned int    invalid = 0;
        int data_stable;

        dfprintk(VFS, "NFS: %s(%s/%ld ct=%d info=0x%x)\n",
                        __FUNCTION__, inode->i_sb->s_id, inode->i_ino,
                        atomic_read(&inode->i_count), fattr->valid);

        if ((fattr->valid & NFS_ATTR_FATTR) == 0)
                return 0;

        if (nfsi->fileid != fattr->fileid)
                goto out_fileid;

        /*
         * Make sure the inode's type hasn't changed.
         */
        if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
                goto out_changed;

        /*
         * Update the read time so we don't revalidate too often.
         */
        nfsi->read_cache_jiffies = fattr->time_start;
        nfsi->last_updated = jiffies;

        /* Are we racing with known updates of the metadata on the server? */
        data_stable = nfs_verify_change_attribute(inode, fattr->time_start);
        if (data_stable)
                nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME);

        /* Do atomic weak cache consistency updates */
        nfs_wcc_update_inode(inode, fattr);

        /* Check if our cached file size is stale */
        new_isize = nfs_size_to_loff_t(fattr->size);
        cur_isize = i_size_read(inode);
        if (new_isize != cur_isize) {
                /* Do we perhaps have any outstanding writes? */
                if (nfsi->npages == 0) {
                        /* No, but did we race with nfs_end_data_update()? */
                        if (data_stable) {
                                inode->i_size = new_isize;
                                invalid |= NFS_INO_INVALID_DATA;
                        }
                        invalid |= NFS_INO_INVALID_ATTR;
                } else if (new_isize > cur_isize) {
                        inode->i_size = new_isize;
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
                }
                nfsi->cache_change_attribute = jiffies;
                dprintk("NFS: isize change on server for file %s/%ld\n",
                                inode->i_sb->s_id, inode->i_ino);
        }

        /* Check if the mtime agrees */
        if (!timespec_equal(&inode->i_mtime, &fattr->mtime)) {
                memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
                dprintk("NFS: mtime change on server for file %s/%ld\n",
                                inode->i_sb->s_id, inode->i_ino);
                invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
                nfsi->cache_change_attribute = jiffies;
        }

        /* If ctime has changed we should definitely clear access+acl caches */
        if (!timespec_equal(&inode->i_ctime, &fattr->ctime)) {
                invalid |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
                nfsi->cache_change_attribute = jiffies;
        }
        memcpy(&inode->i_atime, &fattr->atime, sizeof(inode->i_atime));

        if ((inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO) ||
            inode->i_uid != fattr->uid ||
            inode->i_gid != fattr->gid)
                invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;

        inode->i_mode = fattr->mode;
        inode->i_nlink = fattr->nlink;
        inode->i_uid = fattr->uid;
        inode->i_gid = fattr->gid;

        if (fattr->valid & (NFS_ATTR_FATTR_V3 | NFS_ATTR_FATTR_V4)) {
                /*
                 * report the blocks in 512byte units
                 */
                inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);
                inode->i_blksize = inode->i_sb->s_blocksize;
        } else {
                inode->i_blocks = fattr->du.nfs2.blocks;
                inode->i_blksize = fattr->du.nfs2.blocksize;
        }

        if ((fattr->valid & NFS_ATTR_FATTR_V4)) {
                if (nfsi->change_attr != fattr->change_attr) {
                        dprintk("NFS: change_attr change on server for file %s/%ld\n",
                                        inode->i_sb->s_id, inode->i_ino);
                        nfsi->change_attr = fattr->change_attr;
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                        nfsi->cache_change_attribute = jiffies;
                } else
                        invalid &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA);
        }

        /* Update attrtimeo value if we're out of the unstable period */
        if (invalid & NFS_INO_INVALID_ATTR) {
                nfs_inc_stats(inode, NFSIOS_ATTRINVALIDATE);
                nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
                nfsi->attrtimeo_timestamp = jiffies;
        } else if (time_after(jiffies, nfsi->attrtimeo_timestamp+nfsi->attrtimeo)) {
                if ((nfsi->attrtimeo <<= 1) > NFS_MAXATTRTIMEO(inode))
                        nfsi->attrtimeo = NFS_MAXATTRTIMEO(inode);
                nfsi->attrtimeo_timestamp = jiffies;
        }
        /* Don't invalidate the data if we were to blame */
        if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)
                                || S_ISLNK(inode->i_mode)))
                invalid &= ~NFS_INO_INVALID_DATA;
        if (data_stable)
                invalid &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME|NFS_INO_REVAL_PAGECACHE);
        if (!nfs_have_delegation(inode, FMODE_READ))
                nfsi->cache_validity |= invalid;

        return 0;
 out_changed:
        /*
         * Big trouble! The inode has become a different object.
         */
#ifdef NFS_PARANOIA
        printk(KERN_DEBUG "%s: inode %ld mode changed, %07o to %07o\n",
                        __FUNCTION__, inode->i_ino, inode->i_mode, fattr->mode);
#endif
 out_err:
        /*
         * No need to worry about unhashing the dentry, as the
         * lookup validation will know that the inode is bad.
         * (But we fall through to invalidate the caches.)
         */
        nfs_invalidate_inode(inode);
        return -ESTALE;

 out_fileid:
        printk(KERN_ERR "NFS: server %s error: fileid changed\n"
                "fsid %s: expected fileid 0x%Lx, got 0x%Lx\n",
                NFS_SERVER(inode)->hostname, inode->i_sb->s_id,
                (long long)nfsi->fileid, (long long)fattr->fileid);
        goto out_err;
}

/*
 * File system information
 */

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);
}

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,
};

#ifdef CONFIG_NFS_V4

static void nfs4_clear_inode(struct inode *);


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

/*
 * Clean out any remaining NFSv4 state that might be left over due
 * to open() calls that passed nfs_atomic_lookup, but failed to call
 * nfs_open().
 */
static void nfs4_clear_inode(struct inode *inode)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        /* If we are holding a delegation, return it! */
        nfs_inode_return_delegation(inode);
        /* First call standard NFS clear_inode() code */
        nfs_clear_inode(inode);
        /* Now clear out any remaining state */
        while (!list_empty(&nfsi->open_states)) {
                struct nfs4_state *state;
                
                state = list_entry(nfsi->open_states.next,
                                struct nfs4_state,
                                inode_states);
                dprintk("%s(%s/%Ld): found unclaimed NFSv4 state %p\n",
                                __FUNCTION__,
                                inode->i_sb->s_id,
                                (long long)NFS_FILEID(inode),
                                state);
                BUG_ON(atomic_read(&state->count) != 1);
                nfs4_close_state(state, state->state);
        }
}


static int nfs4_fill_super(struct super_block *sb, struct nfs4_mount_data *data, int silent)
{
        struct nfs_server *server;
        struct nfs4_client *clp = NULL;
        struct rpc_xprt *xprt = NULL;
        struct rpc_clnt *clnt = NULL;
        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;

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

        /* 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;
                }
        }

        down_write(&clp->cl_sem);
        if (IS_ERR(clp->cl_rpcclient)) {
                xprt = xprt_create_proto(data->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;
                }
                clnt = rpc_create_client(xprt, server->hostname, &nfs_program,
                                server->rpc_ops->version, authflavour);
                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)) {
                err = PTR_ERR(clnt);
                dprintk("%s: cannot create RPC client. Error = %d\n",
                                __FUNCTION__, err);
                return err;
        }

        server->client    = clnt;

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

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

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

        sb->s_time_gran = 1;

        sb->s_op = &nfs4_sops;
        err = nfs_sb_init(sb, authflavour);
        if (err == 0)
                return 0;
out_fail:
        if (clp)
                nfs4_put_client(clp);
        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);
}

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,
};

static const int nfs_set_port_min = 0;
static const int nfs_set_port_max = 65535;
static int param_set_port(const char *val, struct kernel_param *kp)
{
        char *endp;
        int num = simple_strtol(val, &endp, 0);
        if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
                return -EINVAL;
        *((int *)kp->arg) = num;
        return 0;
}

module_param_call(callback_tcpport, param_set_port, param_get_int,
                 &nfs_callback_set_tcpport, 0644);

static int param_set_idmap_timeout(const char *val, struct kernel_param *kp)
{
        char *endp;
        int num = simple_strtol(val, &endp, 0);
        int jif = num * HZ;
        if (endp == val || *endp || num < 0 || jif < num)
                return -EINVAL;
        *((int *)kp->arg) = jif;
        return 0;
}

module_param_call(idmap_cache_timeout, param_set_idmap_timeout, param_get_int,
                 &nfs_idmap_cache_timeout, 0644);

#define nfs4_init_once(nfsi) \
        do { \
                INIT_LIST_HEAD(&(nfsi)->open_states); \
                nfsi->delegation = NULL; \
                nfsi->delegation_state = 0; \
                init_rwsem(&nfsi->rwsem); \
        } while(0)

static inline int register_nfs4fs(void)
{
        int ret;

        ret = nfs_register_sysctl();
        if (ret != 0)
                return ret;
        ret = register_filesystem(&nfs4_fs_type);
        if (ret != 0)
                nfs_unregister_sysctl();
        return ret;
}

static inline void unregister_nfs4fs(void)
{
        unregister_filesystem(&nfs4_fs_type);
        nfs_unregister_sysctl();
}
#else
#define nfs4_init_once(nfsi) \
        do { } while (0)
#define register_nfs4fs() (0)
#define unregister_nfs4fs()
#endif

extern int nfs_init_nfspagecache(void);
extern void nfs_destroy_nfspagecache(void);
extern int nfs_init_readpagecache(void);
extern void nfs_destroy_readpagecache(void);
extern int nfs_init_writepagecache(void);
extern void nfs_destroy_writepagecache(void);
#ifdef CONFIG_NFS_DIRECTIO
extern int nfs_init_directcache(void);
extern void nfs_destroy_directcache(void);
#endif

static kmem_cache_t * nfs_inode_cachep;

static struct inode *nfs_alloc_inode(struct super_block *sb)
{
        struct nfs_inode *nfsi;
        nfsi = (struct nfs_inode *)kmem_cache_alloc(nfs_inode_cachep, SLAB_KERNEL);
        if (!nfsi)
                return NULL;
        nfsi->flags = 0UL;
        nfsi->cache_validity = 0UL;
        nfsi->cache_change_attribute = jiffies;
#ifdef CONFIG_NFS_V3_ACL
        nfsi->acl_access = ERR_PTR(-EAGAIN);
        nfsi->acl_default = ERR_PTR(-EAGAIN);
#endif
#ifdef CONFIG_NFS_V4
        nfsi->nfs4_acl = NULL;
#endif /* CONFIG_NFS_V4 */
        return &nfsi->vfs_inode;
}

static void nfs_destroy_inode(struct inode *inode)
{
        kmem_cache_free(nfs_inode_cachep, NFS_I(inode));
}

static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
{
        struct nfs_inode *nfsi = (struct nfs_inode *) foo;

        if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
            SLAB_CTOR_CONSTRUCTOR) {
                inode_init_once(&nfsi->vfs_inode);
                spin_lock_init(&nfsi->req_lock);
                INIT_LIST_HEAD(&nfsi->dirty);
                INIT_LIST_HEAD(&nfsi->commit);
                INIT_LIST_HEAD(&nfsi->open_files);
                INIT_RADIX_TREE(&nfsi->nfs_page_tree, GFP_ATOMIC);
                atomic_set(&nfsi->data_updates, 0);
                nfsi->ndirty = 0;
                nfsi->ncommit = 0;
                nfsi->npages = 0;
                nfs4_init_once(nfsi);
        }
}
 
static int nfs_init_inodecache(void)
{
        nfs_inode_cachep = kmem_cache_create("nfs_inode_cache",
                                             sizeof(struct nfs_inode),
                                             0, (SLAB_RECLAIM_ACCOUNT|
                                                SLAB_MEM_SPREAD),
                                             init_once, NULL);
        if (nfs_inode_cachep == NULL)
                return -ENOMEM;

        return 0;
}

static void nfs_destroy_inodecache(void)
{
        if (kmem_cache_destroy(nfs_inode_cachep))
                printk(KERN_INFO "nfs_inode_cache: not all structures were freed\n");
}

/*
 * Initialize NFS
 */
static int __init init_nfs_fs(void)
{
        int err;

        err = nfs_init_nfspagecache();
        if (err)
                goto out4;

        err = nfs_init_inodecache();
        if (err)
                goto out3;

        err = nfs_init_readpagecache();
        if (err)
                goto out2;

        err = nfs_init_writepagecache();
        if (err)
                goto out1;

#ifdef CONFIG_NFS_DIRECTIO
        err = nfs_init_directcache();
        if (err)
                goto out0;
#endif

#ifdef CONFIG_PROC_FS
        rpc_proc_register(&nfs_rpcstat);
#endif
        err = register_filesystem(&nfs_fs_type);
        if (err)
                goto out;
        if ((err = register_nfs4fs()) != 0)
                goto out;
        return 0;
out:
#ifdef CONFIG_PROC_FS
        rpc_proc_unregister("nfs");
#endif
#ifdef CONFIG_NFS_DIRECTIO
        nfs_destroy_directcache();
out0:
#endif
        nfs_destroy_writepagecache();
out1:
        nfs_destroy_readpagecache();
out2:
        nfs_destroy_inodecache();
out3:
        nfs_destroy_nfspagecache();
out4:
        return err;
}

static void __exit exit_nfs_fs(void)
{
#ifdef CONFIG_NFS_DIRECTIO
        nfs_destroy_directcache();
#endif
        nfs_destroy_writepagecache();
        nfs_destroy_readpagecache();
        nfs_destroy_inodecache();
        nfs_destroy_nfspagecache();
#ifdef CONFIG_PROC_FS
        rpc_proc_unregister("nfs");
#endif
        unregister_filesystem(&nfs_fs_type);
        unregister_nfs4fs();
}

/* Not quite true; I just maintain it */
MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");
MODULE_LICENSE("GPL");

module_init(init_nfs_fs)
module_exit(exit_nfs_fs)