Linux 2.6.21

[linux/fpc-iii.git] / fs / nfsd / vfs.c

#define MSNFS   /* HACK HACK */
/*
 * linux/fs/nfsd/vfs.c
 *
 * File operations used by nfsd. Some of these have been ripped from
 * other parts of the kernel because they weren't exported, others
 * are partial duplicates with added or changed functionality.
 *
 * Note that several functions dget() the dentry upon which they want
 * to act, most notably those that create directory entries. Response
 * dentry's are dput()'d if necessary in the release callback.
 * So if you notice code paths that apparently fail to dput() the
 * dentry, don't worry--they have been taken care of.
 *
 * Copyright (C) 1995-1999 Olaf Kirch <okir@monad.swb.de>
 * Zerocpy NFS support (C) 2002 Hirokazu Takahashi <taka@valinux.co.jp>
 */

#include <linux/string.h>
#include <linux/time.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/major.h>
#include <linux/ext2_fs.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/net.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/in.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/vfs.h>
#include <linux/delay.h>
#include <linux/sunrpc/svc.h>
#include <linux/nfsd/nfsd.h>
#ifdef CONFIG_NFSD_V3
#include <linux/nfs3.h>
#include <linux/nfsd/xdr3.h>
#endif /* CONFIG_NFSD_V3 */
#include <linux/nfsd/nfsfh.h>
#include <linux/quotaops.h>
#include <linux/fsnotify.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/xattr.h>
#ifdef CONFIG_NFSD_V4
#include <linux/nfs4.h>
#include <linux/nfs4_acl.h>
#include <linux/nfsd_idmap.h>
#include <linux/security.h>
#endif /* CONFIG_NFSD_V4 */
#include <linux/jhash.h>

#include <asm/uaccess.h>

#define NFSDDBG_FACILITY                NFSDDBG_FILEOP


/* We must ignore files (but only files) which might have mandatory
 * locks on them because there is no way to know if the accesser has
 * the lock.
 */
#define IS_ISMNDLK(i)   (S_ISREG((i)->i_mode) && MANDATORY_LOCK(i))

/*
 * This is a cache of readahead params that help us choose the proper
 * readahead strategy. Initially, we set all readahead parameters to 0
 * and let the VFS handle things.
 * If you increase the number of cached files very much, you'll need to
 * add a hash table here.
 */
struct raparms {
        struct raparms          *p_next;
        unsigned int            p_count;
        ino_t                   p_ino;
        dev_t                   p_dev;
        int                     p_set;
        struct file_ra_state    p_ra;
        unsigned int            p_hindex;
};

struct raparm_hbucket {
        struct raparms          *pb_head;
        spinlock_t              pb_lock;
} ____cacheline_aligned_in_smp;

static struct raparms *         raparml;
#define RAPARM_HASH_BITS        4
#define RAPARM_HASH_SIZE        (1<<RAPARM_HASH_BITS)
#define RAPARM_HASH_MASK        (RAPARM_HASH_SIZE-1)
static struct raparm_hbucket    raparm_hash[RAPARM_HASH_SIZE];

/* 
 * Called from nfsd_lookup and encode_dirent. Check if we have crossed 
 * a mount point.
 * Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
 *  or nfs_ok having possibly changed *dpp and *expp
 */
int
nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp, 
                        struct svc_export **expp)
{
        struct svc_export *exp = *expp, *exp2 = NULL;
        struct dentry *dentry = *dpp;
        struct vfsmount *mnt = mntget(exp->ex_mnt);
        struct dentry *mounts = dget(dentry);
        int err = 0;

        while (follow_down(&mnt,&mounts)&&d_mountpoint(mounts));

        exp2 = exp_get_by_name(exp->ex_client, mnt, mounts, &rqstp->rq_chandle);
        if (IS_ERR(exp2)) {
                err = PTR_ERR(exp2);
                dput(mounts);
                mntput(mnt);
                goto out;
        }
        if (exp2 && ((exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2))) {
                /* successfully crossed mount point */
                exp_put(exp);
                *expp = exp2;
                dput(dentry);
                *dpp = mounts;
        } else {
                if (exp2) exp_put(exp2);
                dput(mounts);
        }
        mntput(mnt);
out:
        return err;
}

/*
 * Look up one component of a pathname.
 * N.B. After this call _both_ fhp and resfh need an fh_put
 *
 * If the lookup would cross a mountpoint, and the mounted filesystem
 * is exported to the client with NFSEXP_NOHIDE, then the lookup is
 * accepted as it stands and the mounted directory is
 * returned. Otherwise the covered directory is returned.
 * NOTE: this mountpoint crossing is not supported properly by all
 *   clients and is explicitly disallowed for NFSv3
 *      NeilBrown <neilb@cse.unsw.edu.au>
 */
__be32
nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
                                        int len, struct svc_fh *resfh)
{
        struct svc_export       *exp;
        struct dentry           *dparent;
        struct dentry           *dentry;
        __be32                  err;
        int                     host_err;

        dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);

        /* Obtain dentry and export. */
        err = fh_verify(rqstp, fhp, S_IFDIR, MAY_EXEC);
        if (err)
                return err;

        dparent = fhp->fh_dentry;
        exp  = fhp->fh_export;
        exp_get(exp);

        err = nfserr_acces;

        /* Lookup the name, but don't follow links */
        if (isdotent(name, len)) {
                if (len==1)
                        dentry = dget(dparent);
                else if (dparent != exp->ex_dentry) {
                        dentry = dget_parent(dparent);
                } else  if (!EX_NOHIDE(exp))
                        dentry = dget(dparent); /* .. == . just like at / */
                else {
                        /* checking mountpoint crossing is very different when stepping up */
                        struct svc_export *exp2 = NULL;
                        struct dentry *dp;
                        struct vfsmount *mnt = mntget(exp->ex_mnt);
                        dentry = dget(dparent);
                        while(dentry == mnt->mnt_root && follow_up(&mnt, &dentry))
                                ;
                        dp = dget_parent(dentry);
                        dput(dentry);
                        dentry = dp;

                        exp2 = exp_parent(exp->ex_client, mnt, dentry,
                                          &rqstp->rq_chandle);
                        if (IS_ERR(exp2)) {
                                host_err = PTR_ERR(exp2);
                                dput(dentry);
                                mntput(mnt);
                                goto out_nfserr;
                        }
                        if (!exp2) {
                                dput(dentry);
                                dentry = dget(dparent);
                        } else {
                                exp_put(exp);
                                exp = exp2;
                        }
                        mntput(mnt);
                }
        } else {
                fh_lock(fhp);
                dentry = lookup_one_len(name, dparent, len);
                host_err = PTR_ERR(dentry);
                if (IS_ERR(dentry))
                        goto out_nfserr;
                /*
                 * check if we have crossed a mount point ...
                 */
                if (d_mountpoint(dentry)) {
                        if ((host_err = nfsd_cross_mnt(rqstp, &dentry, &exp))) {
                                dput(dentry);
                                goto out_nfserr;
                        }
                }
        }
        /*
         * Note: we compose the file handle now, but as the
         * dentry may be negative, it may need to be updated.
         */
        err = fh_compose(resfh, exp, dentry, fhp);
        if (!err && !dentry->d_inode)
                err = nfserr_noent;
        dput(dentry);
out:
        exp_put(exp);
        return err;

out_nfserr:
        err = nfserrno(host_err);
        goto out;
}

/*
 * Set various file attributes.
 * N.B. After this call fhp needs an fh_put
 */
__be32
nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
             int check_guard, time_t guardtime)
{
        struct dentry   *dentry;
        struct inode    *inode;
        int             accmode = MAY_SATTR;
        int             ftype = 0;
        int             imode;
        __be32          err;
        int             host_err;
        int             size_change = 0;

        if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME | ATTR_SIZE))
                accmode |= MAY_WRITE|MAY_OWNER_OVERRIDE;
        if (iap->ia_valid & ATTR_SIZE)
                ftype = S_IFREG;

        /* Get inode */
        err = fh_verify(rqstp, fhp, ftype, accmode);
        if (err)
                goto out;

        dentry = fhp->fh_dentry;
        inode = dentry->d_inode;

        /* Ignore any mode updates on symlinks */
        if (S_ISLNK(inode->i_mode))
                iap->ia_valid &= ~ATTR_MODE;

        if (!iap->ia_valid)
                goto out;

        /* NFSv2 does not differentiate between "set-[ac]time-to-now"
         * which only requires access, and "set-[ac]time-to-X" which
         * requires ownership.
         * So if it looks like it might be "set both to the same time which
         * is close to now", and if inode_change_ok fails, then we
         * convert to "set to now" instead of "set to explicit time"
         *
         * We only call inode_change_ok as the last test as technically
         * it is not an interface that we should be using.  It is only
         * valid if the filesystem does not define it's own i_op->setattr.
         */
#define BOTH_TIME_SET (ATTR_ATIME_SET | ATTR_MTIME_SET)
#define MAX_TOUCH_TIME_ERROR (30*60)
        if ((iap->ia_valid & BOTH_TIME_SET) == BOTH_TIME_SET
            && iap->ia_mtime.tv_sec == iap->ia_atime.tv_sec
            ) {
            /* Looks probable.  Now just make sure time is in the right ballpark.
             * Solaris, at least, doesn't seem to care what the time request is.
             * We require it be within 30 minutes of now.
             */
            time_t delta = iap->ia_atime.tv_sec - get_seconds();
            if (delta<0) delta = -delta;
            if (delta < MAX_TOUCH_TIME_ERROR &&
                inode_change_ok(inode, iap) != 0) {
                /* turn off ATTR_[AM]TIME_SET but leave ATTR_[AM]TIME
                 * this will cause notify_change to set these times to "now"
                 */
                iap->ia_valid &= ~BOTH_TIME_SET;
            }
        }
            
        /* The size case is special. It changes the file as well as the attributes.  */
        if (iap->ia_valid & ATTR_SIZE) {
                if (iap->ia_size < inode->i_size) {
                        err = nfsd_permission(fhp->fh_export, dentry, MAY_TRUNC|MAY_OWNER_OVERRIDE);
                        if (err)
                                goto out;
                }

                /*
                 * If we are changing the size of the file, then
                 * we need to break all leases.
                 */
                host_err = break_lease(inode, FMODE_WRITE | O_NONBLOCK);
                if (host_err == -EWOULDBLOCK)
                        host_err = -ETIMEDOUT;
                if (host_err) /* ENOMEM or EWOULDBLOCK */
                        goto out_nfserr;

                host_err = get_write_access(inode);
                if (host_err)
                        goto out_nfserr;

                size_change = 1;
                host_err = locks_verify_truncate(inode, NULL, iap->ia_size);
                if (host_err) {
                        put_write_access(inode);
                        goto out_nfserr;
                }
                DQUOT_INIT(inode);
        }

        imode = inode->i_mode;
        if (iap->ia_valid & ATTR_MODE) {
                iap->ia_mode &= S_IALLUGO;
                imode = iap->ia_mode |= (imode & ~S_IALLUGO);
        }

        /* Revoke setuid/setgid bit on chown/chgrp */
        if ((iap->ia_valid & ATTR_UID) && iap->ia_uid != inode->i_uid)
                iap->ia_valid |= ATTR_KILL_SUID;
        if ((iap->ia_valid & ATTR_GID) && iap->ia_gid != inode->i_gid)
                iap->ia_valid |= ATTR_KILL_SGID;

        /* Change the attributes. */

        iap->ia_valid |= ATTR_CTIME;

        err = nfserr_notsync;
        if (!check_guard || guardtime == inode->i_ctime.tv_sec) {
                fh_lock(fhp);
                host_err = notify_change(dentry, iap);
                err = nfserrno(host_err);
                fh_unlock(fhp);
        }
        if (size_change)
                put_write_access(inode);
        if (!err)
                if (EX_ISSYNC(fhp->fh_export))
                        write_inode_now(inode, 1);
out:
        return err;

out_nfserr:
        err = nfserrno(host_err);
        goto out;
}

#if defined(CONFIG_NFSD_V2_ACL) || \
    defined(CONFIG_NFSD_V3_ACL) || \
    defined(CONFIG_NFSD_V4)
static ssize_t nfsd_getxattr(struct dentry *dentry, char *key, void **buf)
{
        ssize_t buflen;

        buflen = vfs_getxattr(dentry, key, NULL, 0);
        if (buflen <= 0)
                return buflen;

        *buf = kmalloc(buflen, GFP_KERNEL);
        if (!*buf)
                return -ENOMEM;

        return vfs_getxattr(dentry, key, *buf, buflen);
}
#endif

#if defined(CONFIG_NFSD_V4)
static int
set_nfsv4_acl_one(struct dentry *dentry, struct posix_acl *pacl, char *key)
{
        int len;
        size_t buflen;
        char *buf = NULL;
        int error = 0;

        buflen = posix_acl_xattr_size(pacl->a_count);
        buf = kmalloc(buflen, GFP_KERNEL);
        error = -ENOMEM;
        if (buf == NULL)
                goto out;

        len = posix_acl_to_xattr(pacl, buf, buflen);
        if (len < 0) {
                error = len;
                goto out;
        }

        error = vfs_setxattr(dentry, key, buf, len, 0);
out:
        kfree(buf);
        return error;
}

__be32
nfsd4_set_nfs4_acl(struct svc_rqst *rqstp, struct svc_fh *fhp,
    struct nfs4_acl *acl)
{
        __be32 error;
        int host_error;
        struct dentry *dentry;
        struct inode *inode;
        struct posix_acl *pacl = NULL, *dpacl = NULL;
        unsigned int flags = 0;

        /* Get inode */
        error = fh_verify(rqstp, fhp, 0 /* S_IFREG */, MAY_SATTR);
        if (error)
                goto out;

        dentry = fhp->fh_dentry;
        inode = dentry->d_inode;
        if (S_ISDIR(inode->i_mode))
                flags = NFS4_ACL_DIR;

        host_error = nfs4_acl_nfsv4_to_posix(acl, &pacl, &dpacl, flags);
        if (host_error == -EINVAL) {
                error = nfserr_attrnotsupp;
                goto out;
        } else if (host_error < 0)
                goto out_nfserr;

        host_error = set_nfsv4_acl_one(dentry, pacl, POSIX_ACL_XATTR_ACCESS);
        if (host_error < 0)
                goto out_nfserr;

        if (S_ISDIR(inode->i_mode)) {
                host_error = set_nfsv4_acl_one(dentry, dpacl, POSIX_ACL_XATTR_DEFAULT);
                if (host_error < 0)
                        goto out_nfserr;
        }

        error = nfs_ok;

out:
        posix_acl_release(pacl);
        posix_acl_release(dpacl);
        return (error);
out_nfserr:
        if (host_error == -EOPNOTSUPP)
                error = nfserr_attrnotsupp;
        else
                error = nfserrno(host_error);
        goto out;
}

static struct posix_acl *
_get_posix_acl(struct dentry *dentry, char *key)
{
        void *buf = NULL;
        struct posix_acl *pacl = NULL;
        int buflen;

        buflen = nfsd_getxattr(dentry, key, &buf);
        if (!buflen)
                buflen = -ENODATA;
        if (buflen <= 0)
                return ERR_PTR(buflen);

        pacl = posix_acl_from_xattr(buf, buflen);
        kfree(buf);
        return pacl;
}

int
nfsd4_get_nfs4_acl(struct svc_rqst *rqstp, struct dentry *dentry, struct nfs4_acl **acl)
{
        struct inode *inode = dentry->d_inode;
        int error = 0;
        struct posix_acl *pacl = NULL, *dpacl = NULL;
        unsigned int flags = 0;

        pacl = _get_posix_acl(dentry, POSIX_ACL_XATTR_ACCESS);
        if (IS_ERR(pacl) && PTR_ERR(pacl) == -ENODATA)
                pacl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
        if (IS_ERR(pacl)) {
                error = PTR_ERR(pacl);
                pacl = NULL;
                goto out;
        }

        if (S_ISDIR(inode->i_mode)) {
                dpacl = _get_posix_acl(dentry, POSIX_ACL_XATTR_DEFAULT);
                if (IS_ERR(dpacl) && PTR_ERR(dpacl) == -ENODATA)
                        dpacl = NULL;
                else if (IS_ERR(dpacl)) {
                        error = PTR_ERR(dpacl);
                        dpacl = NULL;
                        goto out;
                }
                flags = NFS4_ACL_DIR;
        }

        *acl = nfs4_acl_posix_to_nfsv4(pacl, dpacl, flags);
        if (IS_ERR(*acl)) {
                error = PTR_ERR(*acl);
                *acl = NULL;
        }
 out:
        posix_acl_release(pacl);
        posix_acl_release(dpacl);
        return error;
}

#endif /* defined(CONFIG_NFS_V4) */

#ifdef CONFIG_NFSD_V3
/*
 * Check server access rights to a file system object
 */
struct accessmap {
        u32             access;
        int             how;
};
static struct accessmap nfs3_regaccess[] = {
    {   NFS3_ACCESS_READ,       MAY_READ                        },
    {   NFS3_ACCESS_EXECUTE,    MAY_EXEC                        },
    {   NFS3_ACCESS_MODIFY,     MAY_WRITE|MAY_TRUNC             },
    {   NFS3_ACCESS_EXTEND,     MAY_WRITE                       },

    {   0,                      0                               }
};

static struct accessmap nfs3_diraccess[] = {
    {   NFS3_ACCESS_READ,       MAY_READ                        },
    {   NFS3_ACCESS_LOOKUP,     MAY_EXEC                        },
    {   NFS3_ACCESS_MODIFY,     MAY_EXEC|MAY_WRITE|MAY_TRUNC    },
    {   NFS3_ACCESS_EXTEND,     MAY_EXEC|MAY_WRITE              },
    {   NFS3_ACCESS_DELETE,     MAY_REMOVE                      },

    {   0,                      0                               }
};

static struct accessmap nfs3_anyaccess[] = {
        /* Some clients - Solaris 2.6 at least, make an access call
         * to the server to check for access for things like /dev/null
         * (which really, the server doesn't care about).  So
         * We provide simple access checking for them, looking
         * mainly at mode bits, and we make sure to ignore read-only
         * filesystem checks
         */
    {   NFS3_ACCESS_READ,       MAY_READ                        },
    {   NFS3_ACCESS_EXECUTE,    MAY_EXEC                        },
    {   NFS3_ACCESS_MODIFY,     MAY_WRITE|MAY_LOCAL_ACCESS      },
    {   NFS3_ACCESS_EXTEND,     MAY_WRITE|MAY_LOCAL_ACCESS      },

    {   0,                      0                               }
};

__be32
nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
{
        struct accessmap        *map;
        struct svc_export       *export;
        struct dentry           *dentry;
        u32                     query, result = 0, sresult = 0;
        __be32                  error;

        error = fh_verify(rqstp, fhp, 0, MAY_NOP);
        if (error)
                goto out;

        export = fhp->fh_export;
        dentry = fhp->fh_dentry;

        if (S_ISREG(dentry->d_inode->i_mode))
                map = nfs3_regaccess;
        else if (S_ISDIR(dentry->d_inode->i_mode))
                map = nfs3_diraccess;
        else
                map = nfs3_anyaccess;


        query = *access;
        for  (; map->access; map++) {
                if (map->access & query) {
                        __be32 err2;

                        sresult |= map->access;

                        err2 = nfsd_permission(export, dentry, map->how);
                        switch (err2) {
                        case nfs_ok:
                                result |= map->access;
                                break;
                                
                        /* the following error codes just mean the access was not allowed,
                         * rather than an error occurred */
                        case nfserr_rofs:
                        case nfserr_acces:
                        case nfserr_perm:
                                /* simply don't "or" in the access bit. */
                                break;
                        default:
                                error = err2;
                                goto out;
                        }
                }
        }
        *access = result;
        if (supported)
                *supported = sresult;

 out:
        return error;
}
#endif /* CONFIG_NFSD_V3 */



/*
 * Open an existing file or directory.
 * The access argument indicates the type of open (read/write/lock)
 * N.B. After this call fhp needs an fh_put
 */
__be32
nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
                        int access, struct file **filp)
{
        struct dentry   *dentry;
        struct inode    *inode;
        int             flags = O_RDONLY|O_LARGEFILE;
        __be32          err;
        int             host_err;

        /*
         * If we get here, then the client has already done an "open",
         * and (hopefully) checked permission - so allow OWNER_OVERRIDE
         * in case a chmod has now revoked permission.
         */
        err = fh_verify(rqstp, fhp, type, access | MAY_OWNER_OVERRIDE);
        if (err)
                goto out;

        dentry = fhp->fh_dentry;
        inode = dentry->d_inode;

        /* Disallow write access to files with the append-only bit set
         * or any access when mandatory locking enabled
         */
        err = nfserr_perm;
        if (IS_APPEND(inode) && (access & MAY_WRITE))
                goto out;
        if (IS_ISMNDLK(inode))
                goto out;

        if (!inode->i_fop)
                goto out;

        /*
         * Check to see if there are any leases on this file.
         * This may block while leases are broken.
         */
        host_err = break_lease(inode, O_NONBLOCK | ((access & MAY_WRITE) ? FMODE_WRITE : 0));
        if (host_err == -EWOULDBLOCK)
                host_err = -ETIMEDOUT;
        if (host_err) /* NOMEM or WOULDBLOCK */
                goto out_nfserr;

        if (access & MAY_WRITE) {
                if (access & MAY_READ)
                        flags = O_RDWR|O_LARGEFILE;
                else
                        flags = O_WRONLY|O_LARGEFILE;

                DQUOT_INIT(inode);
        }
        *filp = dentry_open(dget(dentry), mntget(fhp->fh_export->ex_mnt), flags);
        if (IS_ERR(*filp))
                host_err = PTR_ERR(*filp);
out_nfserr:
        err = nfserrno(host_err);
out:
        return err;
}

/*
 * Close a file.
 */
void
nfsd_close(struct file *filp)
{
        fput(filp);
}

/*
 * Sync a file
 * As this calls fsync (not fdatasync) there is no need for a write_inode
 * after it.
 */
static inline int nfsd_dosync(struct file *filp, struct dentry *dp,
                              const struct file_operations *fop)
{
        struct inode *inode = dp->d_inode;
        int (*fsync) (struct file *, struct dentry *, int);
        int err;

        err = filemap_fdatawrite(inode->i_mapping);
        if (err == 0 && fop && (fsync = fop->fsync))
                err = fsync(filp, dp, 0);
        if (err == 0)
                err = filemap_fdatawait(inode->i_mapping);

        return err;
}
        

static int
nfsd_sync(struct file *filp)
{
        int err;
        struct inode *inode = filp->f_path.dentry->d_inode;
        dprintk("nfsd: sync file %s\n", filp->f_path.dentry->d_name.name);
        mutex_lock(&inode->i_mutex);
        err=nfsd_dosync(filp, filp->f_path.dentry, filp->f_op);
        mutex_unlock(&inode->i_mutex);

        return err;
}

int
nfsd_sync_dir(struct dentry *dp)
{
        return nfsd_dosync(NULL, dp, dp->d_inode->i_fop);
}

/*
 * Obtain the readahead parameters for the file
 * specified by (dev, ino).
 */

static inline struct raparms *
nfsd_get_raparms(dev_t dev, ino_t ino)
{
        struct raparms  *ra, **rap, **frap = NULL;
        int depth = 0;
        unsigned int hash;
        struct raparm_hbucket *rab;

        hash = jhash_2words(dev, ino, 0xfeedbeef) & RAPARM_HASH_MASK;
        rab = &raparm_hash[hash];

        spin_lock(&rab->pb_lock);
        for (rap = &rab->pb_head; (ra = *rap); rap = &ra->p_next) {
                if (ra->p_ino == ino && ra->p_dev == dev)
                        goto found;
                depth++;
                if (ra->p_count == 0)
                        frap = rap;
        }
        depth = nfsdstats.ra_size*11/10;
        if (!frap) {    
                spin_unlock(&rab->pb_lock);
                return NULL;
        }
        rap = frap;
        ra = *frap;
        ra->p_dev = dev;
        ra->p_ino = ino;
        ra->p_set = 0;
        ra->p_hindex = hash;
found:
        if (rap != &rab->pb_head) {
                *rap = ra->p_next;
                ra->p_next   = rab->pb_head;
                rab->pb_head = ra;
        }
        ra->p_count++;
        nfsdstats.ra_depth[depth*10/nfsdstats.ra_size]++;
        spin_unlock(&rab->pb_lock);
        return ra;
}

/*
 * Grab and keep cached pages assosiated with a file in the svc_rqst
 * so that they can be passed to the netowork sendmsg/sendpage routines
 * directrly. They will be released after the sending has completed.
 */
static int
nfsd_read_actor(read_descriptor_t *desc, struct page *page, unsigned long offset , unsigned long size)
{
        unsigned long count = desc->count;
        struct svc_rqst *rqstp = desc->arg.data;
        struct page **pp = rqstp->rq_respages + rqstp->rq_resused;

        if (size > count)
                size = count;

        if (rqstp->rq_res.page_len == 0) {
                get_page(page);
                put_page(*pp);
                *pp = page;
                rqstp->rq_resused++;
                rqstp->rq_res.page_base = offset;
                rqstp->rq_res.page_len = size;
        } else if (page != pp[-1]) {
                get_page(page);
                if (*pp)
                        put_page(*pp);
                *pp = page;
                rqstp->rq_resused++;
                rqstp->rq_res.page_len += size;
        } else
                rqstp->rq_res.page_len += size;

        desc->count = count - size;
        desc->written += size;
        return size;
}

static __be32
nfsd_vfs_read(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
              loff_t offset, struct kvec *vec, int vlen, unsigned long *count)
{
        struct inode *inode;
        struct raparms  *ra;
        mm_segment_t    oldfs;
        __be32          err;
        int             host_err;

        err = nfserr_perm;
        inode = file->f_path.dentry->d_inode;
#ifdef MSNFS
        if ((fhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
                (!lock_may_read(inode, offset, *count)))
                goto out;
#endif

        /* Get readahead parameters */
        ra = nfsd_get_raparms(inode->i_sb->s_dev, inode->i_ino);

        if (ra && ra->p_set)
                file->f_ra = ra->p_ra;

        if (file->f_op->sendfile && rqstp->rq_sendfile_ok) {
                rqstp->rq_resused = 1;
                host_err = file->f_op->sendfile(file, &offset, *count,
                                                 nfsd_read_actor, rqstp);
        } else {
                oldfs = get_fs();
                set_fs(KERNEL_DS);
                host_err = vfs_readv(file, (struct iovec __user *)vec, vlen, &offset);
                set_fs(oldfs);
        }

        /* Write back readahead params */
        if (ra) {
                struct raparm_hbucket *rab = &raparm_hash[ra->p_hindex];
                spin_lock(&rab->pb_lock);
                ra->p_ra = file->f_ra;
                ra->p_set = 1;
                ra->p_count--;
                spin_unlock(&rab->pb_lock);
        }

        if (host_err >= 0) {
                nfsdstats.io_read += host_err;
                *count = host_err;
                err = 0;
                fsnotify_access(file->f_path.dentry);
        } else 
                err = nfserrno(host_err);
out:
        return err;
}

static void kill_suid(struct dentry *dentry)
{
        struct iattr    ia;
        ia.ia_valid = ATTR_KILL_SUID | ATTR_KILL_SGID;

        mutex_lock(&dentry->d_inode->i_mutex);
        notify_change(dentry, &ia);
        mutex_unlock(&dentry->d_inode->i_mutex);
}

static __be32
nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
                                loff_t offset, struct kvec *vec, int vlen,
                                unsigned long cnt, int *stablep)
{
        struct svc_export       *exp;
        struct dentry           *dentry;
        struct inode            *inode;
        mm_segment_t            oldfs;
        __be32                  err = 0;
        int                     host_err;
        int                     stable = *stablep;

#ifdef MSNFS
        err = nfserr_perm;

        if ((fhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
                (!lock_may_write(file->f_path.dentry->d_inode, offset, cnt)))
                goto out;
#endif

        dentry = file->f_path.dentry;
        inode = dentry->d_inode;
        exp   = fhp->fh_export;

        /*
         * Request sync writes if
         *  -   the sync export option has been set, or
         *  -   the client requested O_SYNC behavior (NFSv3 feature).
         *  -   The file system doesn't support fsync().
         * When gathered writes have been configured for this volume,
         * flushing the data to disk is handled separately below.
         */

        if (file->f_op->fsync == 0) {/* COMMIT3 cannot work */
               stable = 2;
               *stablep = 2; /* FILE_SYNC */
        }

        if (!EX_ISSYNC(exp))
                stable = 0;
        if (stable && !EX_WGATHER(exp))
                file->f_flags |= O_SYNC;

        /* Write the data. */
        oldfs = get_fs(); set_fs(KERNEL_DS);
        host_err = vfs_writev(file, (struct iovec __user *)vec, vlen, &offset);
        set_fs(oldfs);
        if (host_err >= 0) {
                nfsdstats.io_write += cnt;
                fsnotify_modify(file->f_path.dentry);
        }

        /* clear setuid/setgid flag after write */
        if (host_err >= 0 && (inode->i_mode & (S_ISUID | S_ISGID)))
                kill_suid(dentry);

        if (host_err >= 0 && stable) {
                static ino_t    last_ino;
                static dev_t    last_dev;

                /*
                 * Gathered writes: If another process is currently
                 * writing to the file, there's a high chance
                 * this is another nfsd (triggered by a bulk write
                 * from a client's biod). Rather than syncing the
                 * file with each write request, we sleep for 10 msec.
                 *
                 * I don't know if this roughly approximates
                 * C. Juszak's idea of gathered writes, but it's a
                 * nice and simple solution (IMHO), and it seems to
                 * work:-)
                 */
                if (EX_WGATHER(exp)) {
                        if (atomic_read(&inode->i_writecount) > 1
                            || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
                                dprintk("nfsd: write defer %d\n", current->pid);
                                msleep(10);
                                dprintk("nfsd: write resume %d\n", current->pid);
                        }

                        if (inode->i_state & I_DIRTY) {
                                dprintk("nfsd: write sync %d\n", current->pid);
                                host_err=nfsd_sync(file);
                        }
#if 0
                        wake_up(&inode->i_wait);
#endif
                }
                last_ino = inode->i_ino;
                last_dev = inode->i_sb->s_dev;
        }

        dprintk("nfsd: write complete host_err=%d\n", host_err);
        if (host_err >= 0)
                err = 0;
        else 
                err = nfserrno(host_err);
out:
        return err;
}

/*
 * Read data from a file. count must contain the requested read count
 * on entry. On return, *count contains the number of bytes actually read.
 * N.B. After this call fhp needs an fh_put
 */
__be32
nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
                loff_t offset, struct kvec *vec, int vlen,
                unsigned long *count)
{
        __be32          err;

        if (file) {
                err = nfsd_permission(fhp->fh_export, fhp->fh_dentry,
                                MAY_READ|MAY_OWNER_OVERRIDE);
                if (err)
                        goto out;
                err = nfsd_vfs_read(rqstp, fhp, file, offset, vec, vlen, count);
        } else {
                err = nfsd_open(rqstp, fhp, S_IFREG, MAY_READ, &file);
                if (err)
                        goto out;
                err = nfsd_vfs_read(rqstp, fhp, file, offset, vec, vlen, count);
                nfsd_close(file);
        }
out:
        return err;
}

/*
 * Write data to a file.
 * The stable flag requests synchronous writes.
 * N.B. After this call fhp needs an fh_put
 */
__be32
nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
                loff_t offset, struct kvec *vec, int vlen, unsigned long cnt,
                int *stablep)
{
        __be32                  err = 0;

        if (file) {
                err = nfsd_permission(fhp->fh_export, fhp->fh_dentry,
                                MAY_WRITE|MAY_OWNER_OVERRIDE);
                if (err)
                        goto out;
                err = nfsd_vfs_write(rqstp, fhp, file, offset, vec, vlen, cnt,
                                stablep);
        } else {
                err = nfsd_open(rqstp, fhp, S_IFREG, MAY_WRITE, &file);
                if (err)
                        goto out;

                if (cnt)
                        err = nfsd_vfs_write(rqstp, fhp, file, offset, vec, vlen,
                                             cnt, stablep);
                nfsd_close(file);
        }
out:
        return err;
}

#ifdef CONFIG_NFSD_V3
/*
 * Commit all pending writes to stable storage.
 * Strictly speaking, we could sync just the indicated file region here,
 * but there's currently no way we can ask the VFS to do so.
 *
 * Unfortunately we cannot lock the file to make sure we return full WCC
 * data to the client, as locking happens lower down in the filesystem.
 */
__be32
nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
               loff_t offset, unsigned long count)
{
        struct file     *file;
        __be32          err;

        if ((u64)count > ~(u64)offset)
                return nfserr_inval;

        if ((err = nfsd_open(rqstp, fhp, S_IFREG, MAY_WRITE, &file)) != 0)
                return err;
        if (EX_ISSYNC(fhp->fh_export)) {
                if (file->f_op && file->f_op->fsync) {
                        err = nfserrno(nfsd_sync(file));
                } else {
                        err = nfserr_notsupp;
                }
        }

        nfsd_close(file);
        return err;
}
#endif /* CONFIG_NFSD_V3 */

/*
 * Create a file (regular, directory, device, fifo); UNIX sockets 
 * not yet implemented.
 * If the response fh has been verified, the parent directory should
 * already be locked. Note that the parent directory is left locked.
 *
 * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
 */
__be32
nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
                char *fname, int flen, struct iattr *iap,
                int type, dev_t rdev, struct svc_fh *resfhp)
{
        struct dentry   *dentry, *dchild = NULL;
        struct inode    *dirp;
        __be32          err;
        int             host_err;

        err = nfserr_perm;
        if (!flen)
                goto out;
        err = nfserr_exist;
        if (isdotent(fname, flen))
                goto out;

        err = fh_verify(rqstp, fhp, S_IFDIR, MAY_CREATE);
        if (err)
                goto out;

        dentry = fhp->fh_dentry;
        dirp = dentry->d_inode;

        err = nfserr_notdir;
        if(!dirp->i_op || !dirp->i_op->lookup)
                goto out;
        /*
         * Check whether the response file handle has been verified yet.
         * If it has, the parent directory should already be locked.
         */
        if (!resfhp->fh_dentry) {
                /* called from nfsd_proc_mkdir, or possibly nfsd3_proc_create */
                fh_lock_nested(fhp, I_MUTEX_PARENT);
                dchild = lookup_one_len(fname, dentry, flen);
                host_err = PTR_ERR(dchild);
                if (IS_ERR(dchild))
                        goto out_nfserr;
                err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
                if (err)
                        goto out;
        } else {
                /* called from nfsd_proc_create */
                dchild = dget(resfhp->fh_dentry);
                if (!fhp->fh_locked) {
                        /* not actually possible */
                        printk(KERN_ERR
                                "nfsd_create: parent %s/%s not locked!\n",
                                dentry->d_parent->d_name.name,
                                dentry->d_name.name);
                        err = nfserr_io;
                        goto out;
                }
        }
        /*
         * Make sure the child dentry is still negative ...
         */
        err = nfserr_exist;
        if (dchild->d_inode) {
                dprintk("nfsd_create: dentry %s/%s not negative!\n",
                        dentry->d_name.name, dchild->d_name.name);
                goto out; 
        }

        if (!(iap->ia_valid & ATTR_MODE))
                iap->ia_mode = 0;
        iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;

        /*
         * Get the dir op function pointer.
         */
        err = 0;
        switch (type) {
        case S_IFREG:
                host_err = vfs_create(dirp, dchild, iap->ia_mode, NULL);
                break;
        case S_IFDIR:
                host_err = vfs_mkdir(dirp, dchild, iap->ia_mode);
                break;
        case S_IFCHR:
        case S_IFBLK:
        case S_IFIFO:
        case S_IFSOCK:
                host_err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
                break;
        default:
                printk("nfsd: bad file type %o in nfsd_create\n", type);
                host_err = -EINVAL;
        }
        if (host_err < 0)
                goto out_nfserr;

        if (EX_ISSYNC(fhp->fh_export)) {
                err = nfserrno(nfsd_sync_dir(dentry));
                write_inode_now(dchild->d_inode, 1);
        }


        /* Set file attributes. Mode has already been set and
         * setting uid/gid works only for root. Irix appears to
         * send along the gid when it tries to implement setgid
         * directories via NFS.
         */
        if ((iap->ia_valid &= ~(ATTR_UID|ATTR_GID|ATTR_MODE)) != 0) {
                __be32 err2 = nfsd_setattr(rqstp, resfhp, iap, 0, (time_t)0);
                if (err2)
                        err = err2;
        }
        /*
         * Update the file handle to get the new inode info.
         */
        if (!err)
                err = fh_update(resfhp);
out:
        if (dchild && !IS_ERR(dchild))
                dput(dchild);
        return err;

out_nfserr:
        err = nfserrno(host_err);
        goto out;
}

#ifdef CONFIG_NFSD_V3
/*
 * NFSv3 version of nfsd_create
 */
__be32
nfsd_create_v3(struct svc_rqst *rqstp, struct svc_fh *fhp,
                char *fname, int flen, struct iattr *iap,
                struct svc_fh *resfhp, int createmode, u32 *verifier,
                int *truncp, int *created)
{
        struct dentry   *dentry, *dchild = NULL;
        struct inode    *dirp;
        __be32          err;
        int             host_err;
        __u32           v_mtime=0, v_atime=0;

        err = nfserr_perm;
        if (!flen)
                goto out;
        err = nfserr_exist;
        if (isdotent(fname, flen))
                goto out;
        if (!(iap->ia_valid & ATTR_MODE))
                iap->ia_mode = 0;
        err = fh_verify(rqstp, fhp, S_IFDIR, MAY_CREATE);
        if (err)
                goto out;

        dentry = fhp->fh_dentry;
        dirp = dentry->d_inode;

        /* Get all the sanity checks out of the way before
         * we lock the parent. */
        err = nfserr_notdir;
        if(!dirp->i_op || !dirp->i_op->lookup)
                goto out;
        fh_lock_nested(fhp, I_MUTEX_PARENT);

        /*
         * Compose the response file handle.
         */
        dchild = lookup_one_len(fname, dentry, flen);
        host_err = PTR_ERR(dchild);
        if (IS_ERR(dchild))
                goto out_nfserr;

        err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
        if (err)
                goto out;

        if (createmode == NFS3_CREATE_EXCLUSIVE) {
                /* solaris7 gets confused (bugid 4218508) if these have
                 * the high bit set, so just clear the high bits.
                 */
                v_mtime = verifier[0]&0x7fffffff;
                v_atime = verifier[1]&0x7fffffff;
        }
        
        if (dchild->d_inode) {
                err = 0;

                switch (createmode) {
                case NFS3_CREATE_UNCHECKED:
                        if (! S_ISREG(dchild->d_inode->i_mode))
                                err = nfserr_exist;
                        else if (truncp) {
                                /* in nfsv4, we need to treat this case a little
                                 * differently.  we don't want to truncate the
                                 * file now; this would be wrong if the OPEN
                                 * fails for some other reason.  furthermore,
                                 * if the size is nonzero, we should ignore it
                                 * according to spec!
                                 */
                                *truncp = (iap->ia_valid & ATTR_SIZE) && !iap->ia_size;
                        }
                        else {
                                iap->ia_valid &= ATTR_SIZE;
                                goto set_attr;
                        }
                        break;
                case NFS3_CREATE_EXCLUSIVE:
                        if (   dchild->d_inode->i_mtime.tv_sec == v_mtime
                            && dchild->d_inode->i_atime.tv_sec == v_atime
                            && dchild->d_inode->i_size  == 0 )
                                break;
                         /* fallthru */
                case NFS3_CREATE_GUARDED:
                        err = nfserr_exist;
                }
                goto out;
        }

        host_err = vfs_create(dirp, dchild, iap->ia_mode, NULL);
        if (host_err < 0)
                goto out_nfserr;
        if (created)
                *created = 1;

        if (EX_ISSYNC(fhp->fh_export)) {
                err = nfserrno(nfsd_sync_dir(dentry));
                /* setattr will sync the child (or not) */
        }

        if (createmode == NFS3_CREATE_EXCLUSIVE) {
                /* Cram the verifier into atime/mtime */
                iap->ia_valid = ATTR_MTIME|ATTR_ATIME
                        | ATTR_MTIME_SET|ATTR_ATIME_SET;
                /* XXX someone who knows this better please fix it for nsec */ 
                iap->ia_mtime.tv_sec = v_mtime;
                iap->ia_atime.tv_sec = v_atime;
                iap->ia_mtime.tv_nsec = 0;
                iap->ia_atime.tv_nsec = 0;
        }

        /* Set file attributes.
         * Irix appears to send along the gid when it tries to
         * implement setgid directories via NFS. Clear out all that cruft.
         */
 set_attr:
        if ((iap->ia_valid &= ~(ATTR_UID|ATTR_GID|ATTR_MODE)) != 0) {
                __be32 err2 = nfsd_setattr(rqstp, resfhp, iap, 0, (time_t)0);
                if (err2)
                        err = err2;
        }

        /*
         * Update the filehandle to get the new inode info.
         */
        if (!err)
                err = fh_update(resfhp);

 out:
        fh_unlock(fhp);
        if (dchild && !IS_ERR(dchild))
                dput(dchild);
        return err;
 
 out_nfserr:
        err = nfserrno(host_err);
        goto out;
}
#endif /* CONFIG_NFSD_V3 */

/*
 * Read a symlink. On entry, *lenp must contain the maximum path length that
 * fits into the buffer. On return, it contains the true length.
 * N.B. After this call fhp needs an fh_put
 */
__be32
nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
{
        struct dentry   *dentry;
        struct inode    *inode;
        mm_segment_t    oldfs;
        __be32          err;
        int             host_err;

        err = fh_verify(rqstp, fhp, S_IFLNK, MAY_NOP);
        if (err)
                goto out;

        dentry = fhp->fh_dentry;
        inode = dentry->d_inode;

        err = nfserr_inval;
        if (!inode->i_op || !inode->i_op->readlink)
                goto out;

        touch_atime(fhp->fh_export->ex_mnt, dentry);
        /* N.B. Why does this call need a get_fs()??
         * Remove the set_fs and watch the fireworks:-) --okir
         */

        oldfs = get_fs(); set_fs(KERNEL_DS);
        host_err = inode->i_op->readlink(dentry, buf, *lenp);
        set_fs(oldfs);

        if (host_err < 0)
                goto out_nfserr;
        *lenp = host_err;
        err = 0;
out:
        return err;

out_nfserr:
        err = nfserrno(host_err);
        goto out;
}

/*
 * Create a symlink and look up its inode
 * N.B. After this call _both_ fhp and resfhp need an fh_put
 */
__be32
nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
                                char *fname, int flen,
                                char *path,  int plen,
                                struct svc_fh *resfhp,
                                struct iattr *iap)
{
        struct dentry   *dentry, *dnew;
        __be32          err, cerr;
        int             host_err;
        umode_t         mode;

        err = nfserr_noent;
        if (!flen || !plen)
                goto out;
        err = nfserr_exist;
        if (isdotent(fname, flen))
                goto out;

        err = fh_verify(rqstp, fhp, S_IFDIR, MAY_CREATE);
        if (err)
                goto out;
        fh_lock(fhp);
        dentry = fhp->fh_dentry;
        dnew = lookup_one_len(fname, dentry, flen);
        host_err = PTR_ERR(dnew);
        if (IS_ERR(dnew))
                goto out_nfserr;

        mode = S_IALLUGO;
        /* Only the MODE ATTRibute is even vaguely meaningful */
        if (iap && (iap->ia_valid & ATTR_MODE))
                mode = iap->ia_mode & S_IALLUGO;

        if (unlikely(path[plen] != 0)) {
                char *path_alloced = kmalloc(plen+1, GFP_KERNEL);
                if (path_alloced == NULL)
                        host_err = -ENOMEM;
                else {
                        strncpy(path_alloced, path, plen);
                        path_alloced[plen] = 0;
                        host_err = vfs_symlink(dentry->d_inode, dnew, path_alloced, mode);
                        kfree(path_alloced);
                }
        } else
                host_err = vfs_symlink(dentry->d_inode, dnew, path, mode);

        if (!host_err) {
                if (EX_ISSYNC(fhp->fh_export))
                        host_err = nfsd_sync_dir(dentry);
        }
        err = nfserrno(host_err);
        fh_unlock(fhp);

        cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
        dput(dnew);
        if (err==0) err = cerr;
out:
        return err;

out_nfserr:
        err = nfserrno(host_err);
        goto out;
}

/*
 * Create a hardlink
 * N.B. After this call _both_ ffhp and tfhp need an fh_put
 */
__be32
nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
                                char *name, int len, struct svc_fh *tfhp)
{
        struct dentry   *ddir, *dnew, *dold;
        struct inode    *dirp, *dest;
        __be32          err;
        int             host_err;

        err = fh_verify(rqstp, ffhp, S_IFDIR, MAY_CREATE);
        if (err)
                goto out;
        err = fh_verify(rqstp, tfhp, -S_IFDIR, MAY_NOP);
        if (err)
                goto out;

        err = nfserr_perm;
        if (!len)
                goto out;
        err = nfserr_exist;
        if (isdotent(name, len))
                goto out;

        fh_lock_nested(ffhp, I_MUTEX_PARENT);
        ddir = ffhp->fh_dentry;
        dirp = ddir->d_inode;

        dnew = lookup_one_len(name, ddir, len);
        host_err = PTR_ERR(dnew);
        if (IS_ERR(dnew))
                goto out_nfserr;

        dold = tfhp->fh_dentry;
        dest = dold->d_inode;

        host_err = vfs_link(dold, dirp, dnew);
        if (!host_err) {
                if (EX_ISSYNC(ffhp->fh_export)) {
                        err = nfserrno(nfsd_sync_dir(ddir));
                        write_inode_now(dest, 1);
                }
                err = 0;
        } else {
                if (host_err == -EXDEV && rqstp->rq_vers == 2)
                        err = nfserr_acces;
                else
                        err = nfserrno(host_err);
        }

        dput(dnew);
out_unlock:
        fh_unlock(ffhp);
out:
        return err;

out_nfserr:
        err = nfserrno(host_err);
        goto out_unlock;
}

/*
 * Rename a file
 * N.B. After this call _both_ ffhp and tfhp need an fh_put
 */
__be32
nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
                            struct svc_fh *tfhp, char *tname, int tlen)
{
        struct dentry   *fdentry, *tdentry, *odentry, *ndentry, *trap;
        struct inode    *fdir, *tdir;
        __be32          err;
        int             host_err;

        err = fh_verify(rqstp, ffhp, S_IFDIR, MAY_REMOVE);
        if (err)
                goto out;
        err = fh_verify(rqstp, tfhp, S_IFDIR, MAY_CREATE);
        if (err)
                goto out;

        fdentry = ffhp->fh_dentry;
        fdir = fdentry->d_inode;

        tdentry = tfhp->fh_dentry;
        tdir = tdentry->d_inode;

        err = (rqstp->rq_vers == 2) ? nfserr_acces : nfserr_xdev;
        if (ffhp->fh_export != tfhp->fh_export)
                goto out;

        err = nfserr_perm;
        if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
                goto out;

        /* cannot use fh_lock as we need deadlock protective ordering
         * so do it by hand */
        trap = lock_rename(tdentry, fdentry);
        ffhp->fh_locked = tfhp->fh_locked = 1;
        fill_pre_wcc(ffhp);
        fill_pre_wcc(tfhp);

        odentry = lookup_one_len(fname, fdentry, flen);
        host_err = PTR_ERR(odentry);
        if (IS_ERR(odentry))
                goto out_nfserr;

        host_err = -ENOENT;
        if (!odentry->d_inode)
                goto out_dput_old;
        host_err = -EINVAL;
        if (odentry == trap)
                goto out_dput_old;

        ndentry = lookup_one_len(tname, tdentry, tlen);
        host_err = PTR_ERR(ndentry);
        if (IS_ERR(ndentry))
                goto out_dput_old;
        host_err = -ENOTEMPTY;
        if (ndentry == trap)
                goto out_dput_new;

#ifdef MSNFS
        if ((ffhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
                ((atomic_read(&odentry->d_count) > 1)
                 || (atomic_read(&ndentry->d_count) > 1))) {
                        host_err = -EPERM;
        } else
#endif
        host_err = vfs_rename(fdir, odentry, tdir, ndentry);
        if (!host_err && EX_ISSYNC(tfhp->fh_export)) {
                host_err = nfsd_sync_dir(tdentry);
                if (!host_err)
                        host_err = nfsd_sync_dir(fdentry);
        }

 out_dput_new:
        dput(ndentry);
 out_dput_old:
        dput(odentry);
 out_nfserr:
        err = nfserrno(host_err);

        /* we cannot reply on fh_unlock on the two filehandles,
         * as that would do the wrong thing if the two directories
         * were the same, so again we do it by hand
         */
        fill_post_wcc(ffhp);
        fill_post_wcc(tfhp);
        unlock_rename(tdentry, fdentry);
        ffhp->fh_locked = tfhp->fh_locked = 0;

out:
        return err;
}

/*
 * Unlink a file or directory
 * N.B. After this call fhp needs an fh_put
 */
__be32
nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
                                char *fname, int flen)
{
        struct dentry   *dentry, *rdentry;
        struct inode    *dirp;
        __be32          err;
        int             host_err;

        err = nfserr_acces;
        if (!flen || isdotent(fname, flen))
                goto out;
        err = fh_verify(rqstp, fhp, S_IFDIR, MAY_REMOVE);
        if (err)
                goto out;

        fh_lock_nested(fhp, I_MUTEX_PARENT);
        dentry = fhp->fh_dentry;
        dirp = dentry->d_inode;

        rdentry = lookup_one_len(fname, dentry, flen);
        host_err = PTR_ERR(rdentry);
        if (IS_ERR(rdentry))
                goto out_nfserr;

        if (!rdentry->d_inode) {
                dput(rdentry);
                err = nfserr_noent;
                goto out;
        }

        if (!type)
                type = rdentry->d_inode->i_mode & S_IFMT;

        if (type != S_IFDIR) { /* It's UNLINK */
#ifdef MSNFS
                if ((fhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
                        (atomic_read(&rdentry->d_count) > 1)) {
                        host_err = -EPERM;
                } else
#endif
                host_err = vfs_unlink(dirp, rdentry);
        } else { /* It's RMDIR */
                host_err = vfs_rmdir(dirp, rdentry);
        }

        dput(rdentry);

        if (host_err)
                goto out_nfserr;
        if (EX_ISSYNC(fhp->fh_export))
                host_err = nfsd_sync_dir(dentry);

out_nfserr:
        err = nfserrno(host_err);
out:
        return err;
}

/*
 * Read entries from a directory.
 * The  NFSv3/4 verifier we ignore for now.
 */
__be32
nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp, 
             struct readdir_cd *cdp, filldir_t func)
{
        __be32          err;
        int             host_err;
        struct file     *file;
        loff_t          offset = *offsetp;

        err = nfsd_open(rqstp, fhp, S_IFDIR, MAY_READ, &file);
        if (err)
                goto out;

        offset = vfs_llseek(file, offset, 0);
        if (offset < 0) {
                err = nfserrno((int)offset);
                goto out_close;
        }

        /*
         * Read the directory entries. This silly loop is necessary because
         * readdir() is not guaranteed to fill up the entire buffer, but
         * may choose to do less.
         */

        do {
                cdp->err = nfserr_eof; /* will be cleared on successful read */
                host_err = vfs_readdir(file, func, cdp);
        } while (host_err >=0 && cdp->err == nfs_ok);
        if (host_err)
                err = nfserrno(host_err);
        else
                err = cdp->err;
        *offsetp = vfs_llseek(file, 0, 1);

        if (err == nfserr_eof || err == nfserr_toosmall)
                err = nfs_ok; /* can still be found in ->err */
out_close:
        nfsd_close(file);
out:
        return err;
}

/*
 * Get file system stats
 * N.B. After this call fhp needs an fh_put
 */
__be32
nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat)
{
        __be32 err = fh_verify(rqstp, fhp, 0, MAY_NOP);
        if (!err && vfs_statfs(fhp->fh_dentry,stat))
                err = nfserr_io;
        return err;
}

/*
 * Check for a user's access permissions to this inode.
 */
__be32
nfsd_permission(struct svc_export *exp, struct dentry *dentry, int acc)
{
        struct inode    *inode = dentry->d_inode;
        int             err;

        if (acc == MAY_NOP)
                return 0;
#if 0
        dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
                acc,
                (acc & MAY_READ)?       " read"  : "",
                (acc & MAY_WRITE)?      " write" : "",
                (acc & MAY_EXEC)?       " exec"  : "",
                (acc & MAY_SATTR)?      " sattr" : "",
                (acc & MAY_TRUNC)?      " trunc" : "",
                (acc & MAY_LOCK)?       " lock"  : "",
                (acc & MAY_OWNER_OVERRIDE)? " owneroverride" : "",
                inode->i_mode,
                IS_IMMUTABLE(inode)?    " immut" : "",
                IS_APPEND(inode)?       " append" : "",
                IS_RDONLY(inode)?       " ro" : "");
        dprintk("      owner %d/%d user %d/%d\n",
                inode->i_uid, inode->i_gid, current->fsuid, current->fsgid);
#endif

        /* Normally we reject any write/sattr etc access on a read-only file
         * system.  But if it is IRIX doing check on write-access for a 
         * device special file, we ignore rofs.
         */
        if (!(acc & MAY_LOCAL_ACCESS))
                if (acc & (MAY_WRITE | MAY_SATTR | MAY_TRUNC)) {
                        if (EX_RDONLY(exp) || IS_RDONLY(inode))
                                return nfserr_rofs;
                        if (/* (acc & MAY_WRITE) && */ IS_IMMUTABLE(inode))
                                return nfserr_perm;
                }
        if ((acc & MAY_TRUNC) && IS_APPEND(inode))
                return nfserr_perm;

        if (acc & MAY_LOCK) {
                /* If we cannot rely on authentication in NLM requests,
                 * just allow locks, otherwise require read permission, or
                 * ownership
                 */
                if (exp->ex_flags & NFSEXP_NOAUTHNLM)
                        return 0;
                else
                        acc = MAY_READ | MAY_OWNER_OVERRIDE;
        }
        /*
         * The file owner always gets access permission for accesses that
         * would normally be checked at open time. This is to make
         * file access work even when the client has done a fchmod(fd, 0).
         *
         * However, `cp foo bar' should fail nevertheless when bar is
         * readonly. A sensible way to do this might be to reject all
         * attempts to truncate a read-only file, because a creat() call
         * always implies file truncation.
         * ... but this isn't really fair.  A process may reasonably call
         * ftruncate on an open file descriptor on a file with perm 000.
         * We must trust the client to do permission checking - using "ACCESS"
         * with NFSv3.
         */
        if ((acc & MAY_OWNER_OVERRIDE) &&
            inode->i_uid == current->fsuid)
                return 0;

        err = permission(inode, acc & (MAY_READ|MAY_WRITE|MAY_EXEC), NULL);

        /* Allow read access to binaries even when mode 111 */
        if (err == -EACCES && S_ISREG(inode->i_mode) &&
            acc == (MAY_READ | MAY_OWNER_OVERRIDE))
                err = permission(inode, MAY_EXEC, NULL);

        return err? nfserrno(err) : 0;
}

void
nfsd_racache_shutdown(void)
{
        if (!raparml)
                return;
        dprintk("nfsd: freeing readahead buffers.\n");
        kfree(raparml);
        raparml = NULL;
}
/*
 * Initialize readahead param cache
 */
int
nfsd_racache_init(int cache_size)
{
        int     i;
        int     j = 0;
        int     nperbucket;


        if (raparml)
                return 0;
        if (cache_size < 2*RAPARM_HASH_SIZE)
                cache_size = 2*RAPARM_HASH_SIZE;
        raparml = kcalloc(cache_size, sizeof(struct raparms), GFP_KERNEL);

        if (!raparml) {
                printk(KERN_WARNING
                        "nfsd: Could not allocate memory read-ahead cache.\n");
                return -ENOMEM;
        }

        dprintk("nfsd: allocating %d readahead buffers.\n", cache_size);
        for (i = 0 ; i < RAPARM_HASH_SIZE ; i++) {
                raparm_hash[i].pb_head = NULL;
                spin_lock_init(&raparm_hash[i].pb_lock);
        }
        nperbucket = cache_size >> RAPARM_HASH_BITS;
        for (i = 0; i < cache_size - 1; i++) {
                if (i % nperbucket == 0)
                        raparm_hash[j++].pb_head = raparml + i;
                if (i % nperbucket < nperbucket-1)
                        raparml[i].p_next = raparml + i + 1;
        }

        nfsdstats.ra_size = cache_size;
        return 0;
}

#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
struct posix_acl *
nfsd_get_posix_acl(struct svc_fh *fhp, int type)
{
        struct inode *inode = fhp->fh_dentry->d_inode;
        char *name;
        void *value = NULL;
        ssize_t size;
        struct posix_acl *acl;

        if (!IS_POSIXACL(inode))
                return ERR_PTR(-EOPNOTSUPP);

        switch (type) {
        case ACL_TYPE_ACCESS:
                name = POSIX_ACL_XATTR_ACCESS;
                break;
        case ACL_TYPE_DEFAULT:
                name = POSIX_ACL_XATTR_DEFAULT;
                break;
        default:
                return ERR_PTR(-EOPNOTSUPP);
        }

        size = nfsd_getxattr(fhp->fh_dentry, name, &value);
        if (size < 0)
                return ERR_PTR(size);

        acl = posix_acl_from_xattr(value, size);
        kfree(value);
        return acl;
}

int
nfsd_set_posix_acl(struct svc_fh *fhp, int type, struct posix_acl *acl)
{
        struct inode *inode = fhp->fh_dentry->d_inode;
        char *name;
        void *value = NULL;
        size_t size;
        int error;

        if (!IS_POSIXACL(inode) || !inode->i_op ||
            !inode->i_op->setxattr || !inode->i_op->removexattr)
                return -EOPNOTSUPP;
        switch(type) {
                case ACL_TYPE_ACCESS:
                        name = POSIX_ACL_XATTR_ACCESS;
                        break;
                case ACL_TYPE_DEFAULT:
                        name = POSIX_ACL_XATTR_DEFAULT;
                        break;
                default:
                        return -EOPNOTSUPP;
        }

        if (acl && acl->a_count) {
                size = posix_acl_xattr_size(acl->a_count);
                value = kmalloc(size, GFP_KERNEL);
                if (!value)
                        return -ENOMEM;
                error = posix_acl_to_xattr(acl, value, size);
                if (error < 0)
                        goto getout;
                size = error;
        } else
                size = 0;

        if (size)
                error = vfs_setxattr(fhp->fh_dentry, name, value, size, 0);
        else {
                if (!S_ISDIR(inode->i_mode) && type == ACL_TYPE_DEFAULT)
                        error = 0;
                else {
                        error = vfs_removexattr(fhp->fh_dentry, name);
                        if (error == -ENODATA)
                                error = 0;
                }
        }

getout:
        kfree(value);
        return error;
}
#endif  /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */