Linux 2.4.0-test10pre4

[davej-history.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 in ksyms.c, 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>
 */

#include <linux/config.h>
#include <linux/version.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/locks.h>
#include <linux/fs.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/malloc.h>
#include <linux/in.h>
#define __NO_VERSION__
#include <linux/module.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 <asm/uaccess.h>

#define NFSDDBG_FACILITY                NFSDDBG_FILEOP
#define NFSD_PARANOIA


/* 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;
        unsigned long           p_reada,
                                p_ramax,
                                p_raend,
                                p_ralen,
                                p_rawin;
};

static struct raparms *         raparml;
static struct raparms *         raparm_cache;

/*
 * 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_CROSSMNT, 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>
 */
int
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;
        int                     err;

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

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

        dparent = fhp->fh_dentry;
        exp  = fhp->fh_export;

        err = nfserr_acces;

        /* Lookup the name, but don't follow links */
        if (strcmp(name, ".")==0) {
                dentry = dget(dparent);
        } else if (strcmp(name, "..")==0) {
                /* checking mountpoint crossing is very different when stepping up */
                if (dparent == exp->ex_dentry) {
                        if (!EX_CROSSMNT(exp))
                                dentry = dget(dparent); /* .. == . just like at / */
                        else
                        {
                                struct svc_export *exp2 = NULL;
                                struct dentry *dp;
                                struct vfsmount *mnt = mntget(exp->ex_mnt);
                                dentry = dget(dparent);
                                while(follow_up(&mnt, &dentry))
                                        ;
                                dp = dget(dentry->d_parent);
                                dput(dentry);
                                dentry = dp;
                                for ( ; exp2 == NULL && dp->d_parent != dp;
                                     dp=dp->d_parent)
                                        exp2 = exp_get(exp->ex_client, dp->d_inode->i_dev, dp->d_inode->i_ino);
                                if (exp2==NULL) {
                                        dput(dentry);
                                        dentry = dget(dparent);
                                } else {
                                        exp = exp2;
                                }
                                mntput(mnt);
                        }
                } else
                        dentry = dget(dparent->d_parent);
        } else {
                fh_lock(fhp);
                dentry = lookup_one(name, dparent);
                err = PTR_ERR(dentry);
                if (IS_ERR(dentry))
                        goto out_nfserr;
                /*
                 * check if we have crossed a mount point ...
                 */
                if (d_mountpoint(dentry)) {
                        struct svc_export *exp2 = NULL;
                        struct vfsmount *mnt = mntget(exp->ex_mnt);
                        struct dentry *mounts = dget(dentry);
                        while (follow_down(&mnt,&mounts)&&d_mountpoint(mounts))
                                ;
                        exp2 = exp_get(rqstp->rq_client,
                                       mounts->d_inode->i_dev,
                                       mounts->d_inode->i_ino);
                        if (exp2 && EX_CROSSMNT(exp2)) {
                                /* successfully crossed mount point */
                                exp = exp2;
                                dput(dentry);
                                dentry = mounts;
                        } else
                                dput(mounts);
                        mntput(mnt);
                }
        }
        /*
         * 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);
        if (!err && !dentry->d_inode)
                err = nfserr_noent;
out:
        return err;

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

/*
 * Set various file attributes.
 * N.B. After this call fhp needs an fh_put
 */
int
nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap)
{
        struct dentry   *dentry;
        struct inode    *inode;
        int             accmode = MAY_SATTR;
        int             ftype = 0;
        int             imode;
        int             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 || !iap->ia_valid)
                goto out;

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

        err = inode_change_ok(inode, iap);
        /* could be a "touch" (utimes) request where the user is not the owner but does
         * have write permission. In this case the user should be allowed to set
         * both times to the current time.  We could just assume any such SETATTR
         * is intended to set the times to "now", but we do a couple of simple tests
         * to increase our confidence.
         */
#define BOTH_TIME_SET (ATTR_ATIME_SET | ATTR_MTIME_SET)
#define MAX_TOUCH_TIME_ERROR (30*60)
        if (err
            && (iap->ia_valid & BOTH_TIME_SET) == BOTH_TIME_SET
            && iap->ia_mtime == iap->ia_ctime
            ) {
            /* looks good.  now just make sure time is in the right ballpark.
             * solaris, at least, doesn't seem to care what the time request is
             */
            time_t delta = iap->ia_atime - CURRENT_TIME;
            if (delta<0) delta = -delta;
            if (delta < MAX_TOUCH_TIME_ERROR) {
                /* 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;
                err = inode_change_ok(inode, iap);
            }
        }
            
        if (err)
                goto out_nfserr;

        /* 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.
                 */
                err = get_lease(inode, FMODE_WRITE);
                if (err)
                        goto out_nfserr;

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

                err = locks_verify_truncate(inode, NULL, iap->ia_size);
                if (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) && (imode & S_ISUID)
         && iap->ia_uid != inode->i_uid) {
                iap->ia_valid |= ATTR_MODE;
                iap->ia_mode = imode &= ~S_ISUID;
        }
        if ((iap->ia_valid & ATTR_GID) && (imode & S_ISGID)
         && iap->ia_gid != inode->i_gid) {
                iap->ia_valid |= ATTR_MODE;
                iap->ia_mode = imode &= ~S_ISGID;
        }

        /* Change the attributes. */


        iap->ia_valid |= ATTR_CTIME;
#ifdef CONFIG_QUOTA
        /* DQUOT_TRANSFER needs both ia_uid and ia_gid defined */
        if (iap->ia_valid & (ATTR_UID|ATTR_GID)) {
                if (! (iap->ia_valid & ATTR_UID))
                        iap->ia_uid = inode->i_uid;
                if (! (iap->ia_valid & ATTR_GID))
                        iap->ia_gid = inode->i_gid;
                iap->ia_valid |= ATTR_UID|ATTR_GID;
        }
#endif /* CONFIG_QUOTA */

        if (iap->ia_valid & ATTR_SIZE) {
                fh_lock(fhp);
                size_change = 1;
        }
#ifdef CONFIG_QUOTA
        if (iap->ia_valid & (ATTR_UID|ATTR_GID)) 
                err = DQUOT_TRANSFER(dentry, iap);
        else
#endif
                err = notify_change(dentry, iap);
        if (size_change) {
                fh_unlock(fhp);
                put_write_access(inode);
        }
        if (err)
                goto out_nfserr;
        if (EX_ISSYNC(fhp->fh_export))
                write_inode_now(inode, 1);
        err = 0;
out:
        return err;

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

#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[] = {
    /* XXX: should we try to cover read/write here for clients that
     * rely on us to do their access checking for special files? */

    {   0,                      0                               }
};

int
nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access)
{
        struct accessmap        *map;
        struct svc_export       *export;
        struct dentry           *dentry;
        u32                     query, result = 0;
        unsigned int            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) {
                        unsigned int err2;
                        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;

 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
 */
int
nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
                        int access, struct file *filp)
{
        struct dentry   *dentry;
        struct inode    *inode;
        int             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 access to files with the append-only bit set or
         * with mandatory locking enabled
         */
        err = nfserr_perm;
        if (IS_APPEND(inode) || 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.
         */
        err = get_lease(inode, (access & MAY_WRITE) ? FMODE_WRITE : 0);
        if (err)
                goto out_nfserr;

        if ((access & MAY_WRITE) && (err = get_write_access(inode)) != 0)
                goto out_nfserr;

        memset(filp, 0, sizeof(*filp));
        filp->f_op    = fops_get(inode->i_fop);
        atomic_set(&filp->f_count, 1);
        filp->f_dentry = dentry;
        if (access & MAY_WRITE) {
                filp->f_flags = O_WRONLY|O_LARGEFILE;
                filp->f_mode  = FMODE_WRITE;
                DQUOT_INIT(inode);
        } else {
                filp->f_flags = O_RDONLY|O_LARGEFILE;
                filp->f_mode  = FMODE_READ;
        }

        err = 0;
        if (filp->f_op && filp->f_op->open) {
                err = filp->f_op->open(inode, filp);
                if (err) {
                        fops_put(filp->f_op);
                        if (access & MAY_WRITE)
                                put_write_access(inode);

                        /* I nearly added put_filp() call here, but this filp
                         * is really on callers stack frame. -DaveM
                         */
                        atomic_dec(&filp->f_count);
                }
        }
out_nfserr:
        if (err)
                err = nfserrno(err);
out:
        return err;
}

/*
 * Close a file.
 */
void
nfsd_close(struct file *filp)
{
        struct dentry   *dentry = filp->f_dentry;
        struct inode    *inode = dentry->d_inode;

        if (filp->f_op && filp->f_op->release)
                filp->f_op->release(inode, filp);
        fops_put(filp->f_op);
        if (filp->f_mode & FMODE_WRITE)
                put_write_access(inode);
}

/*
 * Sync a file
 * As this calls fsync (not fdatasync) there is no need for a write_inode
 * after it.
 */
void
nfsd_sync(struct file *filp)
{
        dprintk("nfsd: sync file %s\n", filp->f_dentry->d_name.name);
        down(&filp->f_dentry->d_inode->i_sem);
        filp->f_op->fsync(filp, filp->f_dentry, 0);
        up(&filp->f_dentry->d_inode->i_sem);
}

void
nfsd_sync_dir(struct dentry *dp)
{
        struct inode *inode = dp->d_inode;
        int (*fsync) (struct file *, struct dentry *, int);
        
        if (inode->i_fop && (fsync = inode->i_fop->fsync)) {
                fsync(NULL, dp, 0);
        }
}

/*
 * 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;
        
        for (rap = &raparm_cache; (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)
                return NULL;
        rap = frap;
        ra = *frap;
        memset(ra, 0, sizeof(*ra));
        ra->p_dev = dev;
        ra->p_ino = ino;
found:
        if (rap != &raparm_cache) {
                *rap = ra->p_next;
                ra->p_next   = raparm_cache;
                raparm_cache = ra;
        }
        ra->p_count++;
        nfsdstats.ra_depth[depth*10/nfsdstats.ra_size]++;
        return ra;
}

/*
 * 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
 */
int
nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
          char *buf, unsigned long *count)
{
        struct raparms  *ra;
        mm_segment_t    oldfs;
        int             err;
        struct file     file;

        err = nfsd_open(rqstp, fhp, S_IFREG, MAY_READ, &file);
        if (err)
                goto out;
        err = nfserr_perm;
        if (!file.f_op->read)
                goto out_close;
#ifdef MSNFS
        if ((fhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
                (!lock_may_read(file.f_dentry->d_inode, offset, *count)))
                goto out_close;
#endif

        /* Get readahead parameters */
        ra = nfsd_get_raparms(fhp->fh_export->ex_dev, fhp->fh_dentry->d_inode->i_ino);
        if (ra) {
                file.f_reada = ra->p_reada;
                file.f_ramax = ra->p_ramax;
                file.f_raend = ra->p_raend;
                file.f_ralen = ra->p_ralen;
                file.f_rawin = ra->p_rawin;
        }
        file.f_pos = offset;

        oldfs = get_fs(); set_fs(KERNEL_DS);
        err = file.f_op->read(&file, buf, *count, &file.f_pos);
        set_fs(oldfs);

        /* Write back readahead params */
        if (ra != NULL) {
                dprintk("nfsd: raparms %ld %ld %ld %ld %ld\n",
                        file.f_reada, file.f_ramax, file.f_raend,
                        file.f_ralen, file.f_rawin);
                ra->p_reada = file.f_reada;
                ra->p_ramax = file.f_ramax;
                ra->p_raend = file.f_raend;
                ra->p_ralen = file.f_ralen;
                ra->p_rawin = file.f_rawin;
                ra->p_count -= 1;
        }

        if (err >= 0) {
                nfsdstats.io_read += err;
                *count = err;
                err = 0;
        } else 
                err = nfserrno(err);
out_close:
        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
 */
int
nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
                                char *buf, unsigned long cnt, int *stablep)
{
        struct svc_export       *exp;
        struct file             file;
        struct dentry           *dentry;
        struct inode            *inode;
        mm_segment_t            oldfs;
        int                     err = 0;
        int                     stable = *stablep;

        err = nfsd_open(rqstp, fhp, S_IFREG, MAY_WRITE, &file);
        if (err)
                goto out;
        if (!cnt)
                goto out_close;
        err = nfserr_perm;
        if (!file.f_op->write)
                goto out_close;
#ifdef MSNFS
        if ((fhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
                (!lock_may_write(file.f_dentry->d_inode, offset, cnt)))
                goto out_close;
#endif

        dentry = file.f_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;

        file.f_pos = offset;            /* set write offset */

        /* Write the data. */
        oldfs = get_fs(); set_fs(KERNEL_DS);
        err = file.f_op->write(&file, buf, cnt, &file.f_pos);
        if (err >= 0)
                nfsdstats.io_write += cnt;
        set_fs(oldfs);

        /* clear setuid/setgid flag after write */
        if (err >= 0 && (inode->i_mode & (S_ISUID | S_ISGID))) {
                struct iattr    ia;

                ia.ia_valid = ATTR_MODE;
                ia.ia_mode  = inode->i_mode & ~(S_ISUID | S_ISGID);
                notify_change(dentry, &ia);
        }

        if (err >= 0 && stable) {
                static unsigned long    last_ino;
                static kdev_t           last_dev = NODEV;

                /*
                 * 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) && (atomic_read(&inode->i_writecount) > 1
                 || (last_ino == inode->i_ino && last_dev == inode->i_dev))) {
#if 0
                        interruptible_sleep_on_timeout(&inode->i_wait, 10 * HZ / 1000);
#else
                        dprintk("nfsd: write defer %d\n", current->pid);
/* FIXME: Olaf commented this out [gam3] */
                        set_current_state(TASK_UNINTERRUPTIBLE);
                        schedule_timeout((HZ+99)/100);
                        current->state = TASK_RUNNING;
                        dprintk("nfsd: write resume %d\n", current->pid);
#endif
                }

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

        dprintk("nfsd: write complete err=%d\n", err);
        if (err >= 0)
                err = 0;
        else 
                err = nfserrno(err);
out_close:
        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.
 */
int
nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
               off_t offset, unsigned long count)
{
        struct file     file;
        int             err;

        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) {
                        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
 */
int
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;
        struct inode    *dirp;
        int             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(fhp);
                dchild = lookup_one(fname, dentry);
                err = PTR_ERR(dchild);
                if (IS_ERR(dchild))
                        goto out_nfserr;
                err = fh_compose(resfhp, fhp->fh_export, dchild);
                if (err)
                        goto out;
        } else {
                /* called from nfsd_proc_create */
                dchild = 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 = -EIO;
                        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 = nfserr_perm;
        switch (type) {
        case S_IFREG:
                err = vfs_create(dirp, dchild, iap->ia_mode);
                break;
        case S_IFDIR:
                err = vfs_mkdir(dirp, dchild, iap->ia_mode);
                break;
        case S_IFCHR:
        case S_IFBLK:
        case S_IFIFO:
        case S_IFSOCK:
                err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
                break;
        default:
                printk("nfsd: bad file type %o in nfsd_create\n", type);
                err = -EINVAL;
        }
        if (err < 0)
                goto out_nfserr;

        if (EX_ISSYNC(fhp->fh_export)) {
                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.
         */
        err = 0;
        if ((iap->ia_valid &= ~(ATTR_UID|ATTR_GID|ATTR_MODE)) != 0)
                err = nfsd_setattr(rqstp, resfhp, iap);
        /*
         * Update the file handle to get the new inode info.
         */
        if (!err)
                err = fh_update(resfhp);
out:
        return err;

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

#ifdef CONFIG_NFSD_V3
/*
 * NFSv3 version of nfsd_create
 */
int
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)
{
        struct dentry   *dentry, *dchild;
        struct inode    *dirp;
        int             err;
        __u32           v_mtime=0, v_atime=0;
        int             v_mode=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(fhp);

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

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

        if (createmode == NFS3_CREATE_EXCLUSIVE) {
                /* while the verifier would fit in mtime+atime,
                 * solaris7 gets confused (bugid 4218508) if these have
                 * the high bit set, so we use the mode as well
                 */
                v_mtime = verifier[0]&0x7fffffff;
                v_atime = verifier[1]&0x7fffffff;
                v_mode  = S_IFREG
                        | ((verifier[0]&0x80000000) >> (32-7)) /* u+x */
                        | ((verifier[1]&0x80000000) >> (32-9)) /* u+r */
                        ;
        }
        
        if (dchild->d_inode) {
                err = 0;

                switch (createmode) {
                case NFS3_CREATE_UNCHECKED:
                        if (! S_ISREG(dchild->d_inode->i_mode))
                                err = nfserr_exist;
                        else {
                                iap->ia_valid &= ATTR_SIZE;
                                goto set_attr;
                        }
                        break;
                case NFS3_CREATE_EXCLUSIVE:
                        if (   dchild->d_inode->i_mtime == v_mtime
                            && dchild->d_inode->i_atime == v_atime
                            && dchild->d_inode->i_mode  == v_mode
                            && dchild->d_inode->i_size  == 0 )
                                break;
                         /* fallthru */
                case NFS3_CREATE_GUARDED:
                        err = nfserr_exist;
                }
                goto out;
        }

        err = vfs_create(dirp, dchild, iap->ia_mode);
        if (err < 0)
                goto out_nfserr;

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

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

        if (createmode == NFS3_CREATE_EXCLUSIVE) {
                /* Cram the verifier into atime/mtime/mode */
                iap->ia_valid = ATTR_MTIME|ATTR_ATIME
                        | ATTR_MTIME_SET|ATTR_ATIME_SET
                        | ATTR_MODE;
                iap->ia_mtime = v_mtime;
                iap->ia_atime = v_atime;
                iap->ia_mode  = v_mode;
        }

        /* Set file attributes.
         * Mode has already been set but we might need to reset it
         * for CREATE_EXCLUSIVE
         * 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)) != 0)
                err = nfsd_setattr(rqstp, resfhp, iap);

 out:
        fh_unlock(fhp);
        return err;
 
 out_nfserr:
        err = nfserrno(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
 */
int
nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
{
        struct dentry   *dentry;
        struct inode    *inode;
        mm_segment_t    oldfs;
        int             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;

        UPDATE_ATIME(inode);
        /* 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);
        err = inode->i_op->readlink(dentry, buf, *lenp);
        set_fs(oldfs);

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

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

/*
 * Create a symlink and look up its inode
 * N.B. After this call _both_ fhp and resfhp need an fh_put
 */
int
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;
        int             err, cerr;

        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(fname, dentry);
        err = PTR_ERR(dnew);
        if (IS_ERR(dnew))
                goto out_nfserr;

        err = vfs_symlink(dentry->d_inode, dnew, path);
        if (!err) {
                if (EX_ISSYNC(fhp->fh_export))
                        nfsd_sync_dir(dentry);
                if (iap) {
                        iap->ia_valid &= ATTR_MODE /* ~(ATTR_MODE|ATTR_UID|ATTR_GID)*/;
                        if (iap->ia_valid) {
                                iap->ia_valid |= ATTR_CTIME;
                                iap->ia_mode = (iap->ia_mode&S_IALLUGO)
                                        | S_IFLNK;
                                err = notify_change(dnew, iap);
                                if (!err && EX_ISSYNC(fhp->fh_export))
                                        write_inode_now(dentry->d_inode, 1);
                       }
                }
        } else
                err = nfserrno(err);
        fh_unlock(fhp);

        /* Compose the fh so the dentry will be freed ... */
        cerr = fh_compose(resfhp, fhp->fh_export, dnew);
        if (err==0) err = cerr;
out:
        return err;

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

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

        fh_lock(ffhp);
        ddir = ffhp->fh_dentry;
        dirp = ddir->d_inode;

        dnew = lookup_one(fname, ddir);
        err = PTR_ERR(dnew);
        if (IS_ERR(dnew))
                goto out_nfserr;

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

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

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

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

/*
 * Rename a file
 * N.B. After this call _both_ ffhp and tfhp need an fh_put
 */
int
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;
        struct inode    *fdir, *tdir;
        int             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 (fdir->i_dev != tdir->i_dev)
                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 */
        double_down(&tdir->i_sem, &fdir->i_sem);
        ffhp->fh_locked = tfhp->fh_locked = 1;
        fill_pre_wcc(ffhp);
        fill_pre_wcc(tfhp);

        odentry = lookup_one(fname, fdentry);
        err = PTR_ERR(odentry);
        if (IS_ERR(odentry))
                goto out_nfserr;

        err = -ENOENT;
        if (!odentry->d_inode)
                goto out_dput_old;

        ndentry = lookup_one(tname, tdentry);
        err = PTR_ERR(ndentry);
        if (IS_ERR(ndentry))
                goto out_dput_old;


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

 out_dput_old:
        dput(odentry);
 out_nfserr:
        if (err)
                err = nfserrno(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);
        double_up(&tdir->i_sem, &fdir->i_sem);
        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
 */
int
nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
                                char *fname, int flen)
{
        struct dentry   *dentry, *rdentry;
        struct inode    *dirp;
        int             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(fhp);
        dentry = fhp->fh_dentry;
        dirp = dentry->d_inode;

        rdentry = lookup_one(fname, dentry);
        err = PTR_ERR(rdentry);
        if (IS_ERR(rdentry))
                goto out_nfserr;

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

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

        dput(rdentry);

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

out:
        return err;

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

/*
 * Read entries from a directory.
 * The verifier is an NFSv3 thing we ignore for now.
 */
int
nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset, 
             encode_dent_fn func, u32 *buffer, int *countp, u32 *verf)
{
        struct inode    *inode;
        u32             *p;
        int             oldlen, eof, err;
        struct file     file;
        struct readdir_cd cd;

        err = nfsd_open(rqstp, fhp, S_IFDIR, MAY_READ, &file);
        if (err)
                goto out;
        if (offset > ~(u32) 0)
                goto out_close;

        err = nfserr_notdir;
        if (!file.f_op->readdir)
                goto out_close;
        file.f_pos = offset;

        /* Set up the readdir context */
        memset(&cd, 0, sizeof(cd));
        cd.rqstp  = rqstp;
        cd.buffer = buffer;
        cd.buflen = *countp; /* count of words */
        cd.dirfh  = fhp;

        /*
         * 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.
         */
        inode = file.f_dentry->d_inode;
        down(&inode->i_sem);
        while (1) {
                oldlen = cd.buflen;

                /*
                dprintk("nfsd: f_op->readdir(%x/%ld @ %d) buflen = %d (%d)\n",
                        file.f_inode->i_dev, file.f_inode->i_ino,
                        (int) file.f_pos, (int) oldlen, (int) cd.buflen);
                 */
                err = file.f_op->readdir(&file, &cd, (filldir_t) func);
                if (err < 0)
                        goto out_nfserr;
                if (oldlen == cd.buflen)
                        break;
                if (cd.eob)
                        break;
        }
        up(&inode->i_sem);

        /* If we didn't fill the buffer completely, we're at EOF */
        eof = !cd.eob;

        if (cd.offset) {
                if (rqstp->rq_vers == 3)
                        (void)xdr_encode_hyper(cd.offset, file.f_pos);
                else
                        *cd.offset = htonl(file.f_pos);
        }

        p = cd.buffer;
        *p++ = 0;                       /* no more entries */
        *p++ = htonl(eof);              /* end of directory */
        *countp = (caddr_t) p - (caddr_t) buffer;

        dprintk("nfsd: readdir result %d bytes, eof %d offset %d\n",
                                *countp, eof,
                                cd.offset? ntohl(*cd.offset) : -1);
        err = 0;
out_close:
        nfsd_close(&file);
out:
        return err;

out_nfserr:
        up(&inode->i_sem);
        err = nfserrno(err);
        goto out_close;
}

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

/*
 * Check for a user's access permissions to this inode.
 */
int
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

        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));

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

        return err? nfserrno(err) : 0;
}

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

        if (raparm_cache)
                return 0;
        raparml = kmalloc(sizeof(struct raparms) * cache_size, GFP_KERNEL);

        if (raparml != NULL) {
                dprintk("nfsd: allocating %d readahead buffers.\n",
                        cache_size);
                memset(raparml, 0, sizeof(struct raparms) * cache_size);
                for (i = 0; i < cache_size - 1; i++) {
                        raparml[i].p_next = raparml + i + 1;
                }
                raparm_cache = raparml;
        } else {
                printk(KERN_WARNING
                       "nfsd: Could not allocate memory read-ahead cache.\n");
                return -ENOMEM;
        }
        nfsdstats.ra_size = cache_size;
        return 0;
}