/*      $NetBSD: kernfs_vfsops.c,v 1.101 2025/02/16 18:38:58 joe Exp $  */

/*
 * Copyright (c) 1992, 1993, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)kernfs_vfsops.c     8.10 (Berkeley) 5/14/95
 */

/*
 * Kernel params Filesystem
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kernfs_vfsops.c,v 1.101 2025/02/16 18:38:58 joe Exp $");

#ifdef _KERNEL_OPT
#include "opt_compat_netbsd.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/conf.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/dirent.h>
#include <sys/syslog.h>
#include <sys/kauth.h>
#include <sys/module.h>

#include <miscfs/genfs/genfs.h>
#include <miscfs/specfs/specdev.h>
#include <miscfs/kernfs/kernfs.h>

MODULE(MODULE_CLASS_VFS, kernfs, NULL);

dev_t rrootdev = NODEV;
kmutex_t kfs_lock;

VFS_PROTOS(kernfs);

void    kernfs_get_rrootdev(void);

void
kernfs_init(void)
{

        mutex_init(&kfs_lock, MUTEX_DEFAULT, IPL_NONE);
}

void
kernfs_reinit(void)
{

}

void
kernfs_done(void)
{

        mutex_destroy(&kfs_lock);
}

void
kernfs_get_rrootdev(void)
{
        static int tried = 0;

        if (tried) {
                /* Already did it once. */
                return;
        }
        tried = 1;

        if (rootdev == NODEV)
                return;
        rrootdev = devsw_blk2chr(rootdev);
        if (rrootdev != NODEV)
                return;
        rrootdev = NODEV;
        printf("kernfs_get_rrootdev: no raw root device\n");
}

/*
 * Mount the Kernel params filesystem
 */
int
kernfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
{
        struct lwp *l = curlwp;
        int error = 0;
        struct kernfs_mount *fmp;

        if (UIO_MX & (UIO_MX - 1)) {
                log(LOG_ERR, "kernfs: invalid directory entry size");
                return (EINVAL);
        }

        if (mp->mnt_flag & MNT_GETARGS) {
                *data_len = 0;
                return 0;
        }
        /*
         * Update is a no-op
         */
        if (mp->mnt_flag & MNT_UPDATE)
                return (EOPNOTSUPP);

        fmp = kmem_zalloc(sizeof(struct kernfs_mount), KM_SLEEP);
        TAILQ_INIT(&fmp->nodelist);

        mp->mnt_stat.f_namemax = KERNFS_MAXNAMLEN;
        mp->mnt_flag |= MNT_LOCAL;
        mp->mnt_data = fmp;
        vfs_getnewfsid(mp);

        if ((error = set_statvfs_info(path, UIO_USERSPACE, "kernfs",
            UIO_SYSSPACE, mp->mnt_op->vfs_name, mp, l)) != 0) {
                kmem_free(fmp, sizeof(struct kernfs_mount));
                return error;
        }

        kernfs_get_rrootdev();
        return 0;
}

int
kernfs_start(struct mount *mp, int flags)
{

        return (0);
}

int
kernfs_unmount(struct mount *mp, int mntflags)
{
        int error;
        int flags = 0;

        if (mntflags & MNT_FORCE)
                flags |= FORCECLOSE;

        if ((error = vflush(mp, 0, flags)) != 0)
                return (error);

        /*
         * Finally, throw away the kernfs_mount structure
         */
        kmem_free(mp->mnt_data, sizeof(struct kernfs_mount));
        mp->mnt_data = NULL;
        return (0);
}

int
kernfs_root(struct mount *mp, int lktype, struct vnode **vpp)
{
        const struct kern_target *root_target = &kern_targets[0];
        int error;

        /* setup "." */
        error = vcache_get(mp, &root_target, sizeof(root_target), vpp);
        if (error)
                return error;
        error = vn_lock(*vpp, lktype);
        if (error) {
                vrele(*vpp);
                *vpp = NULL;
                return error;
        }
        return 0;
}

/*ARGSUSED*/
int
kernfs_sync(struct mount *mp, int waitfor,
    kauth_cred_t uc)
{

        return (0);
}

/*
 * Kernfs flat namespace lookup.
 * Currently unsupported.
 */
int
kernfs_vget(struct mount *mp, ino_t ino, int lktype,
    struct vnode **vpp)
{

        return (EOPNOTSUPP);
}

int
kernfs_loadvnode(struct mount *mp, struct vnode *vp,
    const void *key, size_t key_len, const void **new_key)
{
        const struct kern_target *kt;
        struct kernfs_node *kfs, *kfsp;
        long *cookie;

        KASSERT(key_len == sizeof(kt));
        memcpy(&kt, key, key_len);

        kfs = kmem_zalloc(sizeof(struct kernfs_node), KM_SLEEP);
        cookie = &(VFSTOKERNFS(mp)->fileno_cookie);
        mutex_enter(&kfs_lock);
again:
        TAILQ_FOREACH(kfsp, &VFSTOKERNFS(mp)->nodelist, kfs_list) {
                if (kfsp->kfs_cookie == *cookie) {
                        (*cookie) ++;
                        goto again;
                }
                if (TAILQ_NEXT(kfsp, kfs_list)) {
                        if (kfsp->kfs_cookie < *cookie &&
                            *cookie < TAILQ_NEXT(kfsp, kfs_list)->kfs_cookie)
                                break;
                        if (kfsp->kfs_cookie + 1 <
                            TAILQ_NEXT(kfsp, kfs_list)->kfs_cookie) {
                                *cookie = kfsp->kfs_cookie + 1;
                                break;
                        }
                }
        }

        kfs->kfs_cookie = *cookie;

        if (kfsp)
                TAILQ_INSERT_AFTER(&VFSTOKERNFS(mp)->nodelist, kfsp, kfs,
                    kfs_list);
        else
                TAILQ_INSERT_TAIL(&VFSTOKERNFS(mp)->nodelist, kfs, kfs_list);

        kfs->kfs_type = kt->kt_tag;
        kfs->kfs_vnode = vp;
        kfs->kfs_fileno = KERNFS_FILENO(kt, kt->kt_tag, kfs->kfs_cookie);
        kfs->kfs_kt = kt;
        kfs->kfs_mode = kt->kt_mode;
        vp->v_tag = VT_KERNFS;
        vp->v_op = kernfs_vnodeop_p;
        vp->v_data = kfs;
        vp->v_type = kt->kt_vtype;
        mutex_exit(&kfs_lock);

        if (kt->kt_tag == KFSkern)
                vp->v_vflag = VV_ROOT;

        if (kt->kt_tag == KFSdevice) {
                vp->v_op = kernfs_specop_p;
                spec_node_init(vp, *(dev_t *)kt->kt_data);
        }

        uvm_vnp_setsize(vp, 0);

        *new_key = &kfs->kfs_kt;
        return 0;
}

extern const struct vnodeopv_desc kernfs_vnodeop_opv_desc;
extern const struct vnodeopv_desc kernfs_specop_opv_desc;

const struct vnodeopv_desc * const kernfs_vnodeopv_descs[] = {
        &kernfs_vnodeop_opv_desc,
        &kernfs_specop_opv_desc,
        NULL,
};

struct vfsops kernfs_vfsops = {
        .vfs_name = MOUNT_KERNFS,
        .vfs_min_mount_data = 0,
        .vfs_mount = kernfs_mount,
        .vfs_start = kernfs_start,
        .vfs_unmount = kernfs_unmount,
        .vfs_root = kernfs_root,
        .vfs_quotactl = (void *)eopnotsupp,
        .vfs_statvfs = genfs_statvfs,
        .vfs_sync = kernfs_sync,
        .vfs_vget = kernfs_vget,
        .vfs_loadvnode = kernfs_loadvnode,
        .vfs_fhtovp = (void *)eopnotsupp,
        .vfs_vptofh = (void *)eopnotsupp,
        .vfs_init = kernfs_init,
        .vfs_reinit = kernfs_reinit,
        .vfs_done = kernfs_done,
        .vfs_snapshot = (void *)eopnotsupp,
        .vfs_extattrctl = vfs_stdextattrctl,
        .vfs_suspendctl = genfs_suspendctl,
        .vfs_renamelock_enter = genfs_renamelock_enter,
        .vfs_renamelock_exit = genfs_renamelock_exit,
        .vfs_fsync = (void *)eopnotsupp,
        .vfs_opv_descs = kernfs_vnodeopv_descs
};

SYSCTL_SETUP(kernfs_sysctl_setup, "kernfs sysctl")
{

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "kernfs",
                       SYSCTL_DESCR("/kern file system"),
                       NULL, 0, NULL, 0,
                       CTL_VFS, 11, CTL_EOL);
        /*
         * XXX the "11" above could be dynamic, thereby eliminating one
         * more instance of the "number to vfs" mapping problem, but
         * "11" is the order as taken from sys/mount.h
         */
}

static int
kernfs_modcmd(modcmd_t cmd, void *arg)
{
        int error;

        switch (cmd) {
        case MODULE_CMD_INIT:
                error = vfs_attach(&kernfs_vfsops);
                break;
        case MODULE_CMD_FINI:
                error = vfs_detach(&kernfs_vfsops);
                break;
        default:
                error = ENOTTY;
                break;
        }

        return (error);
}