fs/sharefs/sharefs_vnops.c

	sharefs_vnops.c revision 1a5e258f5471356ca102c7176637cdce45bac147
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <fs/fs_subr.h>

#include <sys/errno.h>
#include <sys/file.h>
#include <sys/kmem.h>
#include <sys/kobj.h>
#include <sys/cmn_err.h>
#include <sys/stat.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/atomic.h>
#include <sys/vfs.h>
#include <sys/vfs_opreg.h>

#include <sharefs/sharefs.h>

/*
 * sharefs_snap_create: create a large character buffer with
 * the shares enumerated.
 */
static int
sharefs_snap_create(shnode_t *sft)
{
    sharetab_t      *sht;
    share_t         *sh;
    size_t          sWritten = 0;
    int         iCount = 0;
    char            *buf;

    rw_enter(&sharefs_lock, RW_WRITER);
    rw_enter(&sharetab_lock, RW_READER);

    if (sft->sharefs_snap) {
        /*
         * Nothing has changed, so no need to grab a new copy!
         */
        if (sft->sharefs_generation == sharetab_generation) {
            rw_exit(&sharetab_lock);
            rw_exit(&sharefs_lock);
            return (0);
        }

        ASSERT(sft->sharefs_size != 0);
        kmem_free(sft->sharefs_snap, sft->sharefs_size + 1);
        sft->sharefs_snap = NULL;
    }

    sft->sharefs_size = sharetab_size;
    sft->sharefs_count = sharetab_count;

    if (sft->sharefs_size == 0) {
        rw_exit(&sharetab_lock);
        rw_exit(&sharefs_lock);
        return (0);
    }

    sft->sharefs_snap = kmem_zalloc(sft->sharefs_size + 1, KM_SLEEP);

    buf = sft->sharefs_snap;

    /*
     * Walk the Sharetab, dumping each entry.
     */
    for (sht = sharefs_sharetab; sht != NULL; sht = sht->s_next) {
        int i;

        for (i = 0; i < SHARETAB_HASHES; i++) {
            for (sh = sht->s_buckets[i].ssh_sh;
                sh != NULL;
                sh = sh->sh_next) {
                int n;

                if ((sWritten + sh->sh_size) >
                    sft->sharefs_size) {
                    goto error_fault;
                }

                /*
                 * Note that sh->sh_size accounts
                 * for the field seperators.
                 * We need to add one for the EOL
                 * marker. And we should note that
                 * the space is accounted for in
                 * each share by the EOS marker.
                 */
                n = snprintf(&buf[sWritten],
                    sh->sh_size + 1,
                    "%s\t%s\t%s\t%s\t%s\n",
                    sh->sh_path,
                    sh->sh_res,
                    sh->sh_fstype,
                    sh->sh_opts,
                    sh->sh_descr);

                if (n != sh->sh_size) {
                    goto error_fault;
                }

                sWritten += n;
                iCount++;
            }
        }
    }

    /*
     * We want to record the generation number and
     * mtime inside this snapshot.
     */
    gethrestime(&sharetab_snap_time);
    sft->sharefs_snap_time = sharetab_snap_time;
    sft->sharefs_generation = sharetab_generation;

    ASSERT(iCount == sft->sharefs_count);

    rw_exit(&sharetab_lock);
    rw_exit(&sharefs_lock);
    return (0);

error_fault:

    kmem_free(sft->sharefs_snap, sft->sharefs_size + 1);
    sft->sharefs_size = 0;
    sft->sharefs_count = 0;
    sft->sharefs_snap = NULL;
    rw_exit(&sharetab_lock);
    rw_exit(&sharefs_lock);

    return (EFAULT);
}

/* ARGSUSED */
static int
sharefs_getattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr,
    caller_context_t *ct)
{
    timestruc_t now;
    shnode_t    *sft = VTOSH(vp);

    vap->va_type = VREG;
    vap->va_mode = S_IRUSR | S_IRGRP | S_IROTH;
    vap->va_nodeid = SHAREFS_INO_FILE;
    vap->va_nlink = 1;

    rw_enter(&sharefs_lock, RW_READER);

    /*
     * If we get asked about a snapped vnode, then
     * we must report the data in that vnode.
     *
     * Else we report what is currently in the
     * sharetab.
     */
    if (sft->sharefs_real_vp) {
        rw_enter(&sharetab_lock, RW_READER);
        vap->va_size = sharetab_size;
        vap->va_mtime = sharetab_mtime;
        rw_exit(&sharetab_lock);
    } else {
        vap->va_size = sft->sharefs_size;
        vap->va_mtime = sft->sharefs_snap_time;
    }
    rw_exit(&sharefs_lock);

    gethrestime(&now);
    vap->va_atime = vap->va_ctime = now;

    vap->va_uid = 0;
    vap->va_gid = 0;
    vap->va_rdev = 0;
    vap->va_blksize = DEV_BSIZE;
    vap->va_nblocks = howmany(vap->va_size, vap->va_blksize);
    vap->va_seq = 0;
    vap->va_fsid = vp->v_vfsp->vfs_dev;

    return (0);
}

/* ARGSUSED */
static int
sharefs_access(vnode_t *vp, int mode, int flags, cred_t *cr,
    caller_context_t *ct)
{
    if (mode & (VWRITE|VEXEC))
        return (EROFS);

    return (0);
}

/* ARGSUSED */
int
sharefs_open(vnode_t **vpp, int flag, cred_t *cr, caller_context_t *ct)
{
    vnode_t     *vp;
    vnode_t     *ovp = *vpp;
    shnode_t    *sft;
    int     error = 0;

    if (flag & FWRITE)
        return (EINVAL);

    /*
     * Create a new sharefs vnode for each operation. In order to
     * avoid locks, we create a snapshot which can not change during
     * reads.
     */
    vp = gfs_file_create(sizeof (shnode_t), NULL, sharefs_ops_data);

    ((gfs_file_t *)vp->v_data)->gfs_ino = SHAREFS_INO_FILE;

    /*
     * Hold the parent!
     */
    VFS_HOLD(ovp->v_vfsp);

    VN_SET_VFS_TYPE_DEV(vp, ovp->v_vfsp, VREG, 0);

    vp->v_flag |= VROOT | VNOCACHE | VNOMAP | VNOSWAP | VNOMOUNT;

    *vpp = vp;
    VN_RELE(ovp);

    sft = VTOSH(vp);

    /*
     * No need for the lock, no other thread can be accessing
     * this data structure.
     */
    atomic_inc_32(&sft->sharefs_refs);
    sft->sharefs_real_vp = 0;

    /*
     * Since the sharetab could easily change on us whilst we
     * are dumping an extremely huge sharetab, we make a copy
     * of it here and use it to dump instead.
     */
    error = sharefs_snap_create(sft);

    return (error);
}

/* ARGSUSED */
int
sharefs_close(vnode_t *vp, int flag, int count,
    offset_t off, cred_t *cr, caller_context_t *ct)
{
    shnode_t    *sft = VTOSH(vp);

    if (count > 1)
        return (0);

    rw_enter(&sharefs_lock, RW_WRITER);
    if (vp->v_count == 1) {
        if (sft->sharefs_snap != NULL) {
            kmem_free(sft->sharefs_snap, sft->sharefs_size + 1);
            sft->sharefs_size = 0;
            sft->sharefs_snap = NULL;
            sft->sharefs_generation = 0;
        }
    }
    atomic_dec_32(&sft->sharefs_refs);
    rw_exit(&sharefs_lock);

    return (0);
}

/* ARGSUSED */
static int
sharefs_read(vnode_t *vp, uio_t *uio, int ioflag, cred_t *cr,
            caller_context_t *ct)
{
    shnode_t    *sft = VTOSH(vp);
    off_t       off = uio->uio_offset;
    size_t      len = uio->uio_resid;
    int     error = 0;

    rw_enter(&sharefs_lock, RW_READER);

    /*
     * First check to see if we need to grab a new snapshot.
     */
    if (off == (off_t)0) {
        rw_exit(&sharefs_lock);
        error = sharefs_snap_create(sft);
        if (error) {
            return (EFAULT);
        }
        rw_enter(&sharefs_lock, RW_READER);
    }

    /* LINTED */
    if (len <= 0 || off >= sft->sharefs_size) {
        rw_exit(&sharefs_lock);
        return (error);
    }

    if ((size_t)(off + len) > sft->sharefs_size)
        len = sft->sharefs_size - off;

    if (off < 0 || len > sft->sharefs_size) {
        rw_exit(&sharefs_lock);
        return (EFAULT);
    }

    if (len != 0) {
        error = uiomove(sft->sharefs_snap + off,
            len, UIO_READ, uio);
    }

    rw_exit(&sharefs_lock);
    return (error);
}

/* ARGSUSED */
static void
sharefs_inactive(vnode_t *vp, cred_t *cr, caller_context_t *tx)
{
    gfs_file_t  *fp = vp->v_data;
    shnode_t    *sft;

    sft = (shnode_t *)gfs_file_inactive(vp);
    if (sft) {
        rw_enter(&sharefs_lock, RW_WRITER);
        if (sft->sharefs_snap != NULL) {
            kmem_free(sft->sharefs_snap, sft->sharefs_size + 1);
        }

        kmem_free(sft, fp->gfs_size);
        rw_exit(&sharefs_lock);
    }
}

vnode_t *
sharefs_create_root_file(vfs_t *vfsp)
{
    vnode_t     *vp;
    shnode_t    *sft;

    vp = gfs_root_create_file(sizeof (shnode_t),
        vfsp, sharefs_ops_data, SHAREFS_INO_FILE);

    sft = VTOSH(vp);

    sft->sharefs_real_vp = 1;

    return (vp);
}

const fs_operation_def_t sharefs_tops_data[] = {
    { VOPNAME_OPEN,     { .vop_open = sharefs_open } },
    { VOPNAME_CLOSE,    { .vop_close = sharefs_close } },
    { VOPNAME_IOCTL,    { .error = fs_inval } },
    { VOPNAME_GETATTR,  { .vop_getattr = sharefs_getattr } },
    { VOPNAME_ACCESS,   { .vop_access = sharefs_access } },
    { VOPNAME_INACTIVE, { .vop_inactive = sharefs_inactive } },
    { VOPNAME_READ,     { .vop_read = sharefs_read } },
    { VOPNAME_SEEK,     { .vop_seek = fs_seek } },
    { NULL }
};