/*      $NetBSD: mfs_vfsops.c,v 1.117 2025/02/16 18:38:59 joe Exp $     */

/*
 * Copyright (c) 1989, 1990, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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.
 *
 *      @(#)mfs_vfsops.c        8.11 (Berkeley) 6/19/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: mfs_vfsops.c,v 1.117 2025/02/16 18:38:59 joe Exp $");

#if defined(_KERNEL_OPT)
#include "opt_compat_netbsd.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/bufq.h>
#include <sys/mount.h>
#include <sys/signalvar.h>
#include <sys/vnode.h>
#include <sys/kmem.h>
#include <sys/module.h>

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

#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/ufs_extern.h>

#include <ufs/ffs/fs.h>
#include <ufs/ffs/ffs_extern.h>

#include <ufs/mfs/mfsnode.h>
#include <ufs/mfs/mfs_extern.h>

MODULE(MODULE_CLASS_VFS, mfs, "ffs");

kmutex_t mfs_lock;      /* global lock */

/* used for building internal dev_t, minor == 0 reserved for miniroot */
static devminor_t mfs_minor = 1;
static int mfs_initcnt;

extern int (**mfs_vnodeop_p)(void *);

/*
 * mfs vfs operations.
 */

extern const struct vnodeopv_desc mfs_vnodeop_opv_desc;

const struct vnodeopv_desc * const mfs_vnodeopv_descs[] = {
        &mfs_vnodeop_opv_desc,
        NULL,
};

struct vfsops mfs_vfsops = {
        .vfs_name = MOUNT_MFS,
        .vfs_min_mount_data = sizeof (struct mfs_args),
        .vfs_mount = mfs_mount,
        .vfs_start = mfs_start,
        .vfs_unmount = ffs_unmount,
        .vfs_root = ufs_root,
        .vfs_quotactl = ufs_quotactl,
        .vfs_statvfs = mfs_statvfs,
        .vfs_sync = ffs_sync,
        .vfs_vget = ufs_vget,
        .vfs_loadvnode = ffs_loadvnode,
        .vfs_newvnode = ffs_newvnode,
        .vfs_fhtovp = ffs_fhtovp,
        .vfs_vptofh = ffs_vptofh,
        .vfs_init = mfs_init,
        .vfs_reinit = mfs_reinit,
        .vfs_done = mfs_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 = mfs_vnodeopv_descs
};

SYSCTL_SETUP(mfs_sysctl_setup, "mfs sysctl")
{

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_ALIAS,
                       CTLTYPE_NODE, "mfs",
                       SYSCTL_DESCR("Memory based file system"),
                       NULL, 1, NULL, 0,
                       CTL_VFS, 3, CTL_EOL);
        /*
         * XXX the "1" and the "3" above could be dynamic, thereby
         * eliminating one more instance of the "number to vfs"
         * mapping problem, but they are in order as taken from
         * sys/mount.h
         */
}

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

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

        return (error);
}

/*
 * Memory based filesystem initialization.
 */
void
mfs_init(void)
{

        if (mfs_initcnt++ == 0) {
                mutex_init(&mfs_lock, MUTEX_DEFAULT, IPL_NONE);
                ffs_init();
        }
}

void
mfs_reinit(void)
{

        ffs_reinit();
}

void
mfs_done(void)
{

        if (--mfs_initcnt == 0) {
                ffs_done();
                mutex_destroy(&mfs_lock);
        }
}

/*
 * Called by main() when mfs is going to be mounted as root.
 */

int
mfs_mountroot(void)
{
        struct fs *fs;
        struct mount *mp;
        struct lwp *l = curlwp;         /* XXX */
        struct ufsmount *ump;
        struct mfsnode *mfsp;
        int error = 0;

        if ((error = vfs_rootmountalloc(MOUNT_MFS, "mfs_root", &mp))) {
                vrele(rootvp);
                return (error);
        }

        mfsp = kmem_alloc(sizeof(*mfsp), KM_SLEEP);
        rootvp->v_data = mfsp;
        rootvp->v_op = mfs_vnodeop_p;
        rootvp->v_tag = VT_MFS;
        mfsp->mfs_baseoff = mfs_rootbase;
        mfsp->mfs_size = mfs_rootsize;
        mfsp->mfs_vnode = rootvp;
        mfsp->mfs_proc = NULL;          /* indicate kernel space */
        mfsp->mfs_shutdown = 0;
        cv_init(&mfsp->mfs_cv, "mfs");
        mfsp->mfs_refcnt = 1;
        bufq_alloc(&mfsp->mfs_buflist, "fcfs", 0);
        if ((error = ffs_mountfs(rootvp, mp, l)) != 0) {
                vfs_unbusy(mp);
                bufq_free(mfsp->mfs_buflist);
                vfs_rele(mp);
                kmem_free(mfsp, sizeof(*mfsp));
                return (error);
        }
        mountlist_append(mp);
        mp->mnt_vnodecovered = NULLVP;
        ump = VFSTOUFS(mp);
        fs = ump->um_fs;
        (void) copystr(mp->mnt_stat.f_mntonname, fs->fs_fsmnt, MNAMELEN - 1, 0);
        (void)ffs_statvfs(mp, &mp->mnt_stat);
        vfs_unbusy(mp);
        return (0);
}

/*
 * VFS Operations.
 *
 * mount system call
 */
/* ARGSUSED */
int
mfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
{
        struct lwp *l = curlwp;
        struct vnode *devvp;
        struct mfs_args *args = data;
        struct ufsmount *ump;
        struct fs *fs;
        struct mfsnode *mfsp;
        struct proc *p;
        devminor_t minor;
        int flags, error = 0;

        if (args == NULL)
                return EINVAL;
        if (*data_len < sizeof *args)
                return EINVAL;

        p = l->l_proc;
        if (mp->mnt_flag & MNT_GETARGS) {
                struct vnode *vp;

                ump = VFSTOUFS(mp);
                if (ump == NULL)
                        return EIO;

                vp = ump->um_devvp;
                if (vp == NULL)
                        return EIO;

                mfsp = VTOMFS(vp);
                if (mfsp == NULL)
                        return EIO;

                args->fspec = NULL;
                args->base = mfsp->mfs_baseoff;
                args->size = mfsp->mfs_size;
                *data_len = sizeof *args;
                return 0;
        }
        /*
         * XXX turn off async to avoid hangs when writing lots of data.
         * the problem is that MFS needs to allocate pages to clean pages,
         * so if we wait until the last minute to clean pages then there
         * may not be any pages available to do the cleaning.
         * ... and since the default partially-synchronous mode turns out
         * to not be sufficient under heavy load, make it full synchronous.
         */
        mp->mnt_flag &= ~MNT_ASYNC;
        mp->mnt_flag |= MNT_SYNCHRONOUS;

        /*
         * If updating, check whether changing from read-only to
         * read/write; if there is no device name, that's all we do.
         */
        if (mp->mnt_flag & MNT_UPDATE) {
                ump = VFSTOUFS(mp);
                fs = ump->um_fs;
                if (fs->fs_ronly == 0 && (mp->mnt_flag & MNT_RDONLY)) {
                        flags = WRITECLOSE;
                        if (mp->mnt_flag & MNT_FORCE)
                                flags |= FORCECLOSE;
                        error = ffs_flushfiles(mp, flags, l);
                        if (error)
                                return (error);
                }
                if (fs->fs_ronly && (mp->mnt_iflag & IMNT_WANTRDWR))
                        fs->fs_ronly = 0;
                if (args->fspec == NULL)
                        return EINVAL;
                return (0);
        }
        mutex_enter(&mfs_lock);
        minor = mfs_minor++;
        mutex_exit(&mfs_lock);
        error = bdevvp(makedev(255, minor), &devvp);
        if (error)
                return (error);
        mfsp = kmem_alloc(sizeof(*mfsp), KM_SLEEP);
        /*
         * Changing v_op and v_data here is safe as we are
         * the exclusive owner of this device node.
         */
        KASSERT(devvp->v_op == spec_vnodeop_p);
        KASSERT(devvp->v_data == NULL);
        devvp->v_op = mfs_vnodeop_p;
        devvp->v_data = mfsp;
        mfsp->mfs_baseoff = args->base;
        mfsp->mfs_size = args->size;
        mfsp->mfs_vnode = devvp;
        mfsp->mfs_proc = p;
        mfsp->mfs_shutdown = 0;
        cv_init(&mfsp->mfs_cv, "mfsidl");
        mfsp->mfs_refcnt = 1;
        bufq_alloc(&mfsp->mfs_buflist, "fcfs", 0);
        if ((error = ffs_mountfs(devvp, mp, l)) != 0) {
                mfsp->mfs_shutdown = 1;
                vrele(devvp);
                return (error);
        }
        ump = VFSTOUFS(mp);
        fs = ump->um_fs;
        error = set_statvfs_info(path, UIO_USERSPACE, args->fspec,
            UIO_USERSPACE, mp->mnt_op->vfs_name, mp, l);
        if (error)
                return error;
        (void)strncpy(fs->fs_fsmnt, mp->mnt_stat.f_mntonname,
                sizeof(fs->fs_fsmnt));
        fs->fs_fsmnt[sizeof(fs->fs_fsmnt) - 1] = '\0';
        /* XXX: cleanup on error */
        return 0;
}

/*
 * Used to grab the process and keep it in the kernel to service
 * memory filesystem I/O requests.
 *
 * Loop servicing I/O requests.
 * Copy the requested data into or out of the memory filesystem
 * address space.
 */
/* ARGSUSED */
int
mfs_start(struct mount *mp, int flags)
{
        struct vnode *vp;
        struct mfsnode *mfsp;
        struct proc *p;
        struct buf *bp;
        void *base;
        int sleepreturn = 0, refcnt, error;
        ksiginfoq_t kq;

        /*
         * Ensure that file system is still mounted when getting mfsnode.
         * Add a reference to the mfsnode to prevent it disappearing in
         * this routine.
         */
        if ((error = vfs_busy(mp)) != 0)
                return error;
        vp = VFSTOUFS(mp)->um_devvp;
        mfsp = VTOMFS(vp);
        mutex_enter(&mfs_lock);
        mfsp->mfs_refcnt++;
        mutex_exit(&mfs_lock);
        vfs_unbusy(mp);

        base = mfsp->mfs_baseoff;
        mutex_enter(&mfs_lock);
        while (mfsp->mfs_shutdown != 1) {
                while ((bp = bufq_get(mfsp->mfs_buflist)) != NULL) {
                        mutex_exit(&mfs_lock);
                        mfs_doio(bp, base);
                        mutex_enter(&mfs_lock);
                }
                /*
                 * If a non-ignored signal is received, try to unmount.
                 * If that fails, or the filesystem is already in the
                 * process of being unmounted, clear the signal (it has been
                 * "processed"), otherwise we will loop here, as tsleep
                 * will always return EINTR/ERESTART.
                 */
                if (sleepreturn != 0) {
                        mutex_exit(&mfs_lock);
                        if (dounmount(mp, 0, curlwp) != 0) {
                                p = curproc;
                                ksiginfo_queue_init(&kq);
                                mutex_enter(p->p_lock);
                                sigclearall(p, NULL, &kq);
                                mutex_exit(p->p_lock);
                                ksiginfo_queue_drain(&kq);
                        }
                        sleepreturn = 0;
                        mutex_enter(&mfs_lock);
                        continue;
                }

                sleepreturn = cv_wait_sig(&mfsp->mfs_cv, &mfs_lock);
        }
        KASSERT(bufq_peek(mfsp->mfs_buflist) == NULL);
        refcnt = --mfsp->mfs_refcnt;
        mutex_exit(&mfs_lock);
        if (refcnt == 0) {
                bufq_free(mfsp->mfs_buflist);
                cv_destroy(&mfsp->mfs_cv);
                kmem_free(mfsp, sizeof(*mfsp));
        }
        return (sleepreturn);
}

/*
 * Get file system statistics.
 */
int
mfs_statvfs(struct mount *mp, struct statvfs *sbp)
{
        int error;

        error = ffs_statvfs(mp, sbp);
        if (error)
                return error;
        (void)strncpy(sbp->f_fstypename, mp->mnt_op->vfs_name,
            sizeof(sbp->f_fstypename));
        sbp->f_fstypename[sizeof(sbp->f_fstypename) - 1] = '\0';
        return 0;
}