/*      $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);
}

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