fs/fd/fdops.c

	fdops.c revision da6c28aaf62fa55f0fdb8004aa40f88f23bf53f0
/*
 * 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.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All rights reserved.      */


#include <sys/types.h>
#include <sys/param.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/dirent.h>
#include <sys/errno.h>
#include <sys/file.h>
#include <sys/inline.h>
#include <sys/kmem.h>
#include <sys/pathname.h>
#include <sys/resource.h>
#include <sys/statvfs.h>
#include <sys/mount.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/vfs.h>
#include <sys/vfs_opreg.h>
#include <sys/vnode.h>
#include <sys/cred.h>
#include <sys/mntent.h>
#include <sys/mount.h>
#include <sys/user.h>
#include <sys/t_lock.h>
#include <sys/modctl.h>
#include <sys/policy.h>
#include <fs/fs_subr.h>
#include <sys/atomic.h>
#include <sys/mkdev.h>

#define round(r)    (((r)+sizeof (int)-1)&(~(sizeof (int)-1)))
#define fdtoi(n)    ((n)+100)

#define FDDIRSIZE 14
struct fddirect {
    short   d_ino;
    char    d_name[FDDIRSIZE];
};

#define FDROOTINO   2
#define FDSDSIZE    sizeof (struct fddirect)
#define FDNSIZE     10

static int      fdfstype = 0;
static major_t      fdfsmaj;
static minor_t      fdfsmin;
static major_t      fdrmaj;
static kmutex_t     fd_minor_lock;

static int fdget(vnode_t *, char *, vnode_t **);

/* ARGSUSED */
static int
fdopen(vnode_t **vpp, int mode, cred_t *cr, caller_context_t *ct)
{
    if ((*vpp)->v_type != VDIR) {
        mutex_enter(&(*vpp)->v_lock);
        (*vpp)->v_flag |= VDUP;
        mutex_exit(&(*vpp)->v_lock);
    }
    return (0);
}

/* ARGSUSED */
static int
fdclose(vnode_t *vp, int flag, int count, offset_t offset, cred_t *cr,
    caller_context_t *ct)
{
    return (0);
}

/* ARGSUSED */
static int
fdread(vnode_t *vp, uio_t *uiop, int ioflag, cred_t *cr, caller_context_t *ct)
{
    static struct fddirect dotbuf[] = {
        { FDROOTINO, "."  },
        { FDROOTINO, ".." }
    };
    struct fddirect dirbuf;
    int i, n;
    int minfd, maxfd, modoff, error = 0;
    int nentries;
    rctl_qty_t fdno_ctl;
    int endoff;

    if (vp->v_type != VDIR)
        return (ENOSYS);

    mutex_enter(&curproc->p_lock);
    fdno_ctl = rctl_enforced_value(rctlproc_legacy[RLIMIT_NOFILE],
        curproc->p_rctls, curproc);
    nentries = MIN(P_FINFO(curproc)->fi_nfiles, (int)fdno_ctl);
    mutex_exit(&curproc->p_lock);

    endoff = (nentries + 2) * FDSDSIZE;

    /*
     * Fake up ".", "..", and the /dev/fd directory entries.
     */
    if (uiop->uio_loffset < (offset_t)0 ||
        uiop->uio_loffset >= (offset_t)endoff ||
        uiop->uio_resid <= 0)
        return (0);
    ASSERT(uiop->uio_loffset <= MAXOFF_T);
    if (uiop->uio_offset < 2*FDSDSIZE) {
        error = uiomove((caddr_t)dotbuf + uiop->uio_offset,
            MIN(uiop->uio_resid, 2*FDSDSIZE - uiop->uio_offset),
            UIO_READ, uiop);
        if (uiop->uio_resid <= 0 || error)
            return (error);
    }
    minfd = (uiop->uio_offset - 2*FDSDSIZE)/FDSDSIZE;
    maxfd = (uiop->uio_offset + uiop->uio_resid - 1)/FDSDSIZE;
    modoff = uiop->uio_offset % FDSDSIZE;

    for (i = 0; i < FDDIRSIZE; i++)
        dirbuf.d_name[i] = '\0';
    for (i = minfd; i < MIN(maxfd, nentries); i++) {
        n = i;
        dirbuf.d_ino = fdtoi(n);
        numtos((ulong_t)n, dirbuf.d_name);
        error = uiomove((caddr_t)&dirbuf + modoff,
            MIN(uiop->uio_resid, FDSDSIZE - modoff),
            UIO_READ, uiop);
        if (uiop->uio_resid <= 0 || error)
            return (error);
        modoff = 0;
    }

    return (error);
}

/* ARGSUSED */
static int
fdgetattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr,
    caller_context_t *ct)
{
    vfs_t *vfsp = vp->v_vfsp;
    timestruc_t now;

    if (vp->v_type == VDIR) {
        vap->va_nlink = 2;
        vap->va_size = (u_offset_t)
            ((P_FINFO(curproc)->fi_nfiles + 2) * FDSDSIZE);
        vap->va_mode = 0555;
        vap->va_nodeid = (ino64_t)FDROOTINO;
    } else {
        vap->va_nlink = 1;
        vap->va_size = (u_offset_t)0;
        vap->va_mode = 0666;
        vap->va_nodeid = (ino64_t)fdtoi(getminor(vp->v_rdev));
    }
    vap->va_type = vp->v_type;
    vap->va_rdev = vp->v_rdev;
    vap->va_blksize = vfsp->vfs_bsize;
    vap->va_nblocks = (fsblkcnt64_t)0;
    gethrestime(&now);
    vap->va_atime = vap->va_mtime = vap->va_ctime = now;
    vap->va_uid = 0;
    vap->va_gid = 0;
    vap->va_fsid = vfsp->vfs_dev;
    vap->va_seq = 0;
    return (0);
}

/* ARGSUSED */
static int
fdaccess(vnode_t *vp, int mode, int flags, cred_t *cr, caller_context_t *ct)
{
    return (0);
}

/* ARGSUSED */
static int
fdlookup(vnode_t *dp, char *comp, vnode_t **vpp, pathname_t *pnp,
    int flags, vnode_t *rdir, cred_t *cr, caller_context_t *ct,
    int *direntflags, pathname_t *realpnp)
{
    if (comp[0] == 0 || strcmp(comp, ".") == 0 || strcmp(comp, "..") == 0) {
        VN_HOLD(dp);
        *vpp = dp;
        return (0);
    }
    return (fdget(dp, comp, vpp));
}

/* ARGSUSED */
static int
fdcreate(vnode_t *dvp, char *comp, vattr_t *vap, enum vcexcl excl,
    int mode, vnode_t **vpp, cred_t *cr, int flag, caller_context_t *ct,
    vsecattr_t *vsecp)
{
    return (fdget(dvp, comp, vpp));
}

/* ARGSUSED */
static int
fdreaddir(vnode_t *vp, uio_t *uiop, cred_t *cr, int *eofp, caller_context_t *ct,
    int flags)
{
    /* bp holds one dirent structure */
    u_offset_t bp[DIRENT64_RECLEN(FDNSIZE) / sizeof (u_offset_t)];
    struct dirent64 *dirent = (struct dirent64 *)bp;
    int reclen, nentries;
    rctl_qty_t fdno_ctl;
    int  n;
    int oresid;
    off_t off;

    if (uiop->uio_offset < 0 || uiop->uio_resid <= 0 ||
        (uiop->uio_offset % FDSDSIZE) != 0)
        return (ENOENT);

    ASSERT(uiop->uio_loffset <= MAXOFF_T);
    oresid = uiop->uio_resid;
    bzero(bp, sizeof (bp));

    mutex_enter(&curproc->p_lock);
    fdno_ctl = rctl_enforced_value(rctlproc_legacy[RLIMIT_NOFILE],
        curproc->p_rctls, curproc);
    nentries = MIN(P_FINFO(curproc)->fi_nfiles, (int)fdno_ctl);
    mutex_exit(&curproc->p_lock);

    while (uiop->uio_resid > 0) {
        if ((off = uiop->uio_offset) == 0) {    /* "." */
            dirent->d_ino = (ino64_t)FDROOTINO;
            dirent->d_name[0] = '.';
            dirent->d_name[1] = '\0';
            reclen = DIRENT64_RECLEN(1);
        } else if (off == FDSDSIZE) {       /* ".." */
            dirent->d_ino = (ino64_t)FDROOTINO;
            dirent->d_name[0] = '.';
            dirent->d_name[1] = '.';
            dirent->d_name[2] = '\0';
            reclen = DIRENT64_RECLEN(2);
        } else {
            /*
             * Return entries corresponding to the allowable
             * number of file descriptors for this process.
             */
            if ((n = (off-2*FDSDSIZE)/FDSDSIZE) >= nentries)
                break;
            dirent->d_ino = (ino64_t)fdtoi(n);
            numtos((ulong_t)n, dirent->d_name);
            reclen = DIRENT64_RECLEN(strlen(dirent->d_name));
        }
        dirent->d_off = (offset_t)(uiop->uio_offset + FDSDSIZE);
        dirent->d_reclen = (ushort_t)reclen;

        if (reclen > uiop->uio_resid) {
            /*
             * Error if no entries have been returned yet.
             */
            if (uiop->uio_resid == oresid)
                return (EINVAL);
            break;
        }
        /*
         * uiomove() updates both resid and offset by the same
         * amount.  But we want offset to change in increments
         * of FDSDSIZE, which is different from the number of bytes
         * being returned to the user.  So we set uio_offset
         * separately, ignoring what uiomove() does.
         */
        if (uiomove((caddr_t)dirent, reclen, UIO_READ, uiop))
            return (EFAULT);
        uiop->uio_offset = off + FDSDSIZE;
    }
    if (eofp)
        *eofp = ((uiop->uio_offset-2*FDSDSIZE)/FDSDSIZE >= nentries);
    return (0);
}

/* ARGSUSED */
static void
fdinactive(vnode_t *vp, cred_t *cr, caller_context_t *ct)
{
    mutex_enter(&vp->v_lock);
    ASSERT(vp->v_count >= 1);
    if (--vp->v_count != 0) {
        mutex_exit(&vp->v_lock);
        return;
    }
    mutex_exit(&vp->v_lock);
    vn_invalid(vp);
    vn_free(vp);
}

static struct vnodeops *fd_vnodeops;

static const fs_operation_def_t fd_vnodeops_template[] = {
    VOPNAME_OPEN,       { .vop_open = fdopen },
    VOPNAME_CLOSE,      { .vop_close = fdclose },
    VOPNAME_READ,       { .vop_read = fdread },
    VOPNAME_GETATTR,    { .vop_getattr = fdgetattr },
    VOPNAME_ACCESS,     { .vop_access = fdaccess },
    VOPNAME_LOOKUP,     { .vop_lookup = fdlookup },
    VOPNAME_CREATE,     { .vop_create = fdcreate },
    VOPNAME_READDIR,    { .vop_readdir = fdreaddir },
    VOPNAME_INACTIVE,   { .vop_inactive = fdinactive },
    VOPNAME_FRLOCK,     { .error = fs_error },
    VOPNAME_POLL,       { .error = fs_error },
    VOPNAME_DISPOSE,    { .error = fs_error },
    NULL,           NULL
};

static int
fdget(struct vnode *dvp, char *comp, struct vnode **vpp)
{
    int n = 0;
    struct vnode *vp;

    while (*comp) {
        if (*comp < '0' || *comp > '9')
            return (ENOENT);
        n = 10 * n + *comp++ - '0';
    }
    vp = vn_alloc(KM_SLEEP);
    vp->v_type = VCHR;
    vp->v_vfsp = dvp->v_vfsp;
    vn_setops(vp, fd_vnodeops);
    vp->v_data = NULL;
    vp->v_flag = VNOMAP;
    vp->v_rdev = makedevice(fdrmaj, n);
    vn_exists(vp);
    *vpp = vp;
    return (0);
}

/*
 * fdfs is mounted on /dev/fd, however, there are two interesting
 * possibilities - two threads racing to do the same mount (protected
 * by vfs locking), and two threads mounting fdfs in different places.
 */
/*ARGSUSED*/
static int
fdmount(vfs_t *vfsp, vnode_t *mvp, struct mounta *uap, cred_t *cr)
{
    struct vnode *vp;

    if (secpolicy_fs_mount(cr, mvp, vfsp) != 0)
        return (EPERM);
    if (mvp->v_type != VDIR)
        return (ENOTDIR);

    mutex_enter(&mvp->v_lock);
    if ((uap->flags & MS_OVERLAY) == 0 &&
        (mvp->v_count > 1 || (mvp->v_flag & VROOT))) {
        mutex_exit(&mvp->v_lock);
        return (EBUSY);
    }
    mutex_exit(&mvp->v_lock);

    /*
     * Having the resource be anything but "fd" doesn't make sense
     */
    vfs_setresource(vfsp, "fd");

    vp = vn_alloc(KM_SLEEP);
    vp->v_vfsp = vfsp;
    vn_setops(vp, fd_vnodeops);
    vp->v_type = VDIR;
    vp->v_data = NULL;
    vp->v_flag |= VROOT;
    vfsp->vfs_fstype = fdfstype;
    vfsp->vfs_data = (char *)vp;
    mutex_enter(&fd_minor_lock);
    do {
        fdfsmin = (fdfsmin + 1) & L_MAXMIN32;
        vfsp->vfs_dev = makedevice(fdfsmaj, fdfsmin);
    } while (vfs_devismounted(vfsp->vfs_dev));
    mutex_exit(&fd_minor_lock);
    vfs_make_fsid(&vfsp->vfs_fsid, vfsp->vfs_dev, fdfstype);
    vfsp->vfs_bsize = 1024;
    return (0);
}

/* ARGSUSED */
static int
fdunmount(vfs_t *vfsp, int flag, cred_t *cr)
{
    vnode_t *rvp;

    if (secpolicy_fs_unmount(cr, vfsp) != 0)
        return (EPERM);

    /*
     * forced unmount is not supported by this file system
     * and thus, ENOTSUP, is being returned.
     */
    if (flag & MS_FORCE)
        return (ENOTSUP);

    rvp = (vnode_t *)vfsp->vfs_data;
    if (rvp->v_count > 1)
        return (EBUSY);

    VN_RELE(rvp);
    return (0);
}

/* ARGSUSED */
static int
fdroot(vfs_t *vfsp, vnode_t **vpp)
{
    vnode_t *vp = (vnode_t *)vfsp->vfs_data;

    VN_HOLD(vp);
    *vpp = vp;
    return (0);
}

/*
 * No locking required because I held the root vnode before calling this
 * function so the vfs won't disappear on me.  To be more explicit:
 * fdvrootp->v_count will be greater than 1 so fdunmount will just return.
 */
static int
fdstatvfs(struct vfs *vfsp, struct statvfs64 *sp)
{
    dev32_t d32;
    rctl_qty_t fdno_ctl;

    mutex_enter(&curproc->p_lock);
    fdno_ctl = rctl_enforced_value(rctlproc_legacy[RLIMIT_NOFILE],
        curproc->p_rctls, curproc);
    mutex_exit(&curproc->p_lock);

    bzero(sp, sizeof (*sp));
    sp->f_bsize = 1024;
    sp->f_frsize = 1024;
    sp->f_blocks = (fsblkcnt64_t)0;
    sp->f_bfree = (fsblkcnt64_t)0;
    sp->f_bavail = (fsblkcnt64_t)0;
    sp->f_files = (fsfilcnt64_t)
        (MIN(P_FINFO(curproc)->fi_nfiles, fdno_ctl + 2));
    sp->f_ffree = (fsfilcnt64_t)0;
    sp->f_favail = (fsfilcnt64_t)0;
    (void) cmpldev(&d32, vfsp->vfs_dev);
    sp->f_fsid = d32;
    (void) strcpy(sp->f_basetype, vfssw[fdfstype].vsw_name);
    sp->f_flag = vf_to_stf(vfsp->vfs_flag);
    sp->f_namemax = FDNSIZE;
    (void) strcpy(sp->f_fstr, "/dev/fd");
    (void) strcpy(&sp->f_fstr[8], "/dev/fd");
    return (0);
}

int
fdinit(int fstype, char *name)
{
    static const fs_operation_def_t fd_vfsops_template[] = {
        VFSNAME_MOUNT,      { .vfs_mount = fdmount },
        VFSNAME_UNMOUNT,    { .vfs_unmount = fdunmount },
        VFSNAME_ROOT,       { .vfs_root = fdroot },
        VFSNAME_STATVFS,    { .vfs_statvfs = fdstatvfs },
        NULL,           NULL
    };
    int error;

    fdfstype = fstype;
    ASSERT(fdfstype != 0);

    /*
     * Associate VFS ops vector with this fstype.
     */
    error = vfs_setfsops(fstype, fd_vfsops_template, NULL);
    if (error != 0) {
        cmn_err(CE_WARN, "fdinit: bad vnode ops template");
        return (error);
    }

    error = vn_make_ops(name, fd_vnodeops_template, &fd_vnodeops);
    if (error != 0) {
        (void) vfs_freevfsops_by_type(fstype);
        cmn_err(CE_WARN, "fdinit: bad vnode ops template");
        return (error);
    }

    /*
     * Assign unique "device" numbers (reported by stat(2)).
     */
    fdfsmaj = getudev();
    fdrmaj = getudev();
    if (fdfsmaj == (major_t)-1 || fdrmaj == (major_t)-1) {
        cmn_err(CE_WARN, "fdinit: can't get unique device numbers");
        if (fdfsmaj == (major_t)-1)
            fdfsmaj = 0;
        if (fdrmaj == (major_t)-1)
            fdrmaj = 0;
    }
    mutex_init(&fd_minor_lock, NULL, MUTEX_DEFAULT, NULL);
    return (0);
}

/*
 * FDFS Mount options table
 */
static char *rw_cancel[] = { MNTOPT_RO, NULL };

static mntopt_t mntopts[] = {
/*
 *  option name     cancel option   default arg flags
 */
    { MNTOPT_RW,        rw_cancel,  NULL,       MO_DEFAULT,
        (void *)MNTOPT_NOINTR },
    { MNTOPT_IGNORE,    NULL,       NULL,       0,
        (void *)0 },
};

static mntopts_t fdfs_mntopts = {
    sizeof (mntopts) / sizeof (mntopt_t),
    mntopts
};

static vfsdef_t vfw = {
    VFSDEF_VERSION,
    "fd",
    fdinit,
    VSW_HASPROTO,
    &fdfs_mntopts
};

static struct modlfs modlfs = {
    &mod_fsops,
    "filesystem for fd",
    &vfw
};

static struct modlinkage modlinkage = {
    MODREV_1,
    &modlfs,
    NULL
};

int
_init(void)
{
    return (mod_install(&modlinkage));
}

int
_info(struct modinfo *modinfop)
{
    return (mod_info(&modlinkage, modinfop));
}