/*
 * 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
 * $FreeBSD: src/sys/ufs/mfs/mfs_vfsops.c,v 1.81.2.3 2001/07/04 17:35:21 tegge Exp $
 */


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/mount.h>
#include <sys/signalvar.h>
#include <sys/signal2.h>
#include <sys/spinlock2.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/sysmsg.h>
#include <sys/mman.h>
#include <sys/linker.h>
#include <sys/fcntl.h>
#include <sys/nlookup.h>
#include <sys/devfs.h>

#include <vm/vm.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vnode_pager.h>
#include <vm/vm_extern.h>

#include <sys/buf2.h>
#include <sys/thread2.h>

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

#include "mfsnode.h"
#include "mfs_extern.h"

MALLOC_DEFINE(M_MFSNODE, "MFS node", "MFS vnode private part");

static int      mfs_mount (struct mount *mp,
                        char *path, caddr_t data, struct ucred *td);
static int      mfs_start (struct mount *mp, int flags);
static int      mfs_statfs (struct mount *mp, struct statfs *sbp,
                        struct ucred *cred); 
static int      mfs_init (struct vfsconf *);
static void     mfs_doio(struct bio *bio, struct mfsnode *mfsp);

d_open_t        mfsopen;
d_close_t       mfsclose;
d_strategy_t    mfsstrategy;

static struct dev_ops mfs_ops = {
        { "MFS", -1, D_DISK | D_NOEMERGPGR },
        .d_open =       mfsopen,
        .d_close =      mfsclose,
        .d_read =       physread,
        .d_write =      physwrite,
        .d_strategy =   mfsstrategy,
};

/*
 * mfs vfs operations.
 */
static struct vfsops mfs_vfsops = {
        .vfs_flags =            0,
        .vfs_mount =            mfs_mount,
        .vfs_start =            mfs_start,
        .vfs_unmount =          ffs_unmount,
        .vfs_root =             ufs_root,
        .vfs_quotactl =         ufs_quotactl,
        .vfs_statfs =           mfs_statfs,
        .vfs_sync =             ffs_sync,
        .vfs_vget =             ffs_vget,
        .vfs_fhtovp =           ffs_fhtovp,
        .vfs_checkexp =         ufs_check_export,
        .vfs_vptofh =           ffs_vptofh,
        .vfs_init =             mfs_init
};

VFS_SET(mfs_vfsops, mfs, 0);
MODULE_VERSION(mfs, 1);

/*
 * We allow the underlying MFS block device to be opened and read.
 */
int
mfsopen(struct dev_open_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;

#if 0
        if (ap->a_oflags & FWRITE)
                return(EROFS);
#endif
        if (dev->si_drv1)
                return(0);
        return(ENXIO);
}

int
mfsclose(struct dev_close_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct mfsnode *mfsp;

        if ((mfsp = dev->si_drv1) == NULL)
                return(0);
        mfsp->mfs_active = 0;
        wakeup((caddr_t)mfsp);
        return(0);
}

int
mfsstrategy(struct dev_strategy_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct bio *bio = ap->a_bio;
        struct buf *bp = bio->bio_buf;
        off_t boff = bio->bio_offset;
        off_t eoff = boff + bp->b_bcount;
        struct mfsnode *mfsp;

        if ((mfsp = dev->si_drv1) == NULL) {
                bp->b_error = ENXIO;
                goto error;
        }
        if (boff < 0)
                goto bad;
        if (eoff > mfsp->mfs_size) {
                if (boff > mfsp->mfs_size || (bp->b_flags & B_BNOCLIP))
                        goto bad;
                /*
                 * Return EOF by completing the I/O with 0 bytes transfered.
                 * Set B_INVAL to indicate that any data in the buffer is not
                 * valid.
                 */
                if (boff == mfsp->mfs_size) {
                        bp->b_resid = bp->b_bcount;
                        bp->b_flags |= B_INVAL;
                        goto done;
                }
                bp->b_bcount = mfsp->mfs_size - boff;
        }

        /*
         * Initiate I/O
         */
        if (mfsp->mfs_td == curthread) {
                mfs_doio(bio, mfsp);
        } else {
                bioq_insert_tail(&mfsp->bio_queue, bio);
                wakeup((caddr_t)mfsp);
        }
        return(0);

        /*
         * Failure conditions on bio
         */
bad:
        bp->b_error = EINVAL;
error:
        bp->b_flags |= B_ERROR | B_INVAL;
done:
        biodone(bio);
        return(0);
}

/*
 * mfs_mount
 *
 * Called when mounting local physical media
 *
 * PARAMETERS:
 *              mountroot
 *                      mp      mount point structure
 *                      path    NULL (flag for root mount!!!)
 *                      data    <unused>
 *                      ndp     <unused>
 *                      p       process (user credentials check [statfs])
 *
 *              mount
 *                      mp      mount point structure
 *                      path    path to mount point
 *                      data    pointer to argument struct in user space
 *                      ndp     mount point namei() return (used for
 *                              credentials on reload), reused to look
 *                              up block device.
 *                      p       process (user credentials check)
 *
 * RETURNS:     0       Success
 *              !0      error number (errno.h)
 *
 * LOCK STATE:
 *
 *              ENTRY
 *                      mount point is locked
 *              EXIT
 *                      mount point is locked
 *
 * NOTES:
 *              A NULL path can be used for a flag since the mount
 *              system call will fail with EFAULT in copyinstr in
 *              namei() if it is a genuine NULL from the user.
 */
/* ARGSUSED */
static int
mfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
{
        struct vnode *devvp;
        struct mfs_args args;
        struct ufsmount *ump;
        struct fs *fs;
        struct mfsnode *mfsp;
        struct nlookupdata nd;
        size_t size;
        char devname[16];
        int flags;
        int minnum;
        int error;
        cdev_t dev;

        /*
         * Use NULL path to flag a root mount
         */
        if (path == NULL) {
                /*
                 ***
                 * Mounting root file system
                 ***
                 */

                /* you lose */
                panic("mfs_mount: mount MFS as root: not configured!");
        }

        mfsp = NULL;

        /*
         ***
         * Mounting non-root file system or updating a file system
         ***
         */

        /* copy in user arguments*/
        error = copyin(data, (caddr_t)&args, sizeof (struct mfs_args));
        if (error)
                goto error_1;

        /*
         * 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) {
                /*
                 ********************
                 * 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);
                        if (error)
                                goto error_1;
                }
                if (fs->fs_ronly && (mp->mnt_kern_flag & MNTK_WANTRDWR)) {
                        /* XXX reopen the device vnode read-write */
                        fs->fs_ronly = 0;
                }
                /* if not updating name...*/
                if (args.fspec == 0) {
                        /*
                         * Process export requests.  Jumping to "success"
                         * will return the vfs_export() error code. 
                         */
                        error = vfs_export(mp, &ump->um_export, &args.export);
                        goto success;
                }

                /* XXX MFS does not support name updating*/
                goto success;
        }

        /*
         * Do the MALLOC before the make_dev since doing so afterward
         * might cause a bogus v_data pointer to get dereferenced
         * elsewhere if MALLOC should block.
         */
        mfsp = kmalloc(sizeof *mfsp, M_MFSNODE, M_WAITOK | M_ZERO);

        minnum = (int)curproc->p_pid;

        dev = make_dev(&mfs_ops, minnum, UID_ROOT, GID_WHEEL, 0600,
                       "mfs%d", minnum);
        /* It is not clear that these will get initialized otherwise */
        dev->si_bsize_phys = DEV_BSIZE;
        dev->si_iosize_max = MAXPHYS;
        dev->si_drv1 = mfsp;
        mfsp->mfs_baseoff = args.base;
        mfsp->mfs_size = args.size;
        mfsp->mfs_dev = dev;
        mfsp->mfs_td = curthread;
        mfsp->mfs_active = 1;
        bioq_init(&mfsp->bio_queue);

        devfs_config(); /* sync devfs work */
        ksnprintf(devname, sizeof(devname), "/dev/mfs%d", minnum);
        nlookup_init(&nd, devname, UIO_SYSSPACE, 0);
        devvp = NULL;
        error = nlookup(&nd);
        if (error == 0) {
                devvp = nd.nl_nch.ncp->nc_vp;
                if (devvp == NULL)
                        error = ENOENT;
                error = vget(devvp, LK_SHARED);
        }
        nlookup_done(&nd);

        if (error)
                goto error_1;
        vn_unlock(devvp);

        /*
         * Our 'block' device must be backed by a VM object.  Theoretically
         * we could use the anonymous memory VM object supplied by userland,
         * but it would be somewhat of a complex task to deal with it
         * that way since it would result in I/O requests which supply
         * the VM pages from our own object.
         *
         * vnode_pager_alloc() is typically called when a VM object is
         * being referenced externally.  We have to undo the refs for
         * the self reference between vnode and object.
         */
        vnode_pager_setsize(devvp, args.size);

        /* Save "mounted from" info for mount point (NULL pad)*/
        copyinstr(args.fspec,                   /* device name*/
                  mp->mnt_stat.f_mntfromname,   /* save area*/
                  MNAMELEN - 1,                 /* max size*/
                  &size);                       /* real size*/
        bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
        /* vref is eaten by mount? */

        error = ffs_mountfs(devvp, mp, M_MFSNODE);
        if (error) {
                mfsp->mfs_active = 0;
                goto error_2;
        }

        /*
         * Initialize FS stat information in mount struct; uses
         * mp->mnt_stat.f_mntfromname.
         *
         * This code is common to root and non-root mounts
         */
        VFS_STATFS(mp, &mp->mnt_stat, cred);

        /*
         * Mark VFS_START MPSAFE; this is to avoid accessing
         * per-mount token after VFS_START exits
         */
        mp->mnt_kern_flag |= MNTK_ST_MPSAFE;

        goto success;

error_2:        /* error with devvp held*/
        vrele(devvp);

error_1:        /* no state to back out*/
        if (mfsp) {
                if (mfsp->mfs_dev) {
                        destroy_dev(mfsp->mfs_dev);
                        mfsp->mfs_dev = NULL;
                }
                kfree(mfsp, M_MFSNODE);
        }

success:
        return(error);
}

/*
 * 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 */
static int
mfs_start(struct mount *mp, int flags)
{
        struct vnode *vp = VFSTOUFS(mp)->um_devvp;
        struct mfsnode *mfsp = vp->v_rdev->si_drv1;
        struct bio *bio;
        struct buf *bp;
        int gotsig = 0, sig;
        thread_t td = curthread;

        /*
         * We must prevent the system from trying to swap
         * out or kill ( when swap space is low, see vm/pageout.c ) the
         * process.  A deadlock can occur if the process is swapped out,
         * and the system can loop trying to kill the unkillable ( while
         * references exist ) MFS process when swap space is low.
         */
        KKASSERT(curproc);
        PHOLD(curproc);

        mfsp->mfs_td = td;

        while (mfsp->mfs_active) {
                crit_enter();

                while ((bio = bioq_takefirst(&mfsp->bio_queue)) != NULL) {
                        crit_exit();
                        bp = bio->bio_buf;
                        mfs_doio(bio, mfsp);
                        wakeup(bp);
                        crit_enter();
                }

                crit_exit();

                /*
                 * If a non-ignored signal is received, try to unmount.
                 * If that fails, clear the signal (it has been "processed"),
                 * otherwise we will loop here, as tsleep will always return
                 * EINTR/ERESTART.
                 */
                /*
                 * Note that dounmount() may fail if work was queued after
                 * we slept. We have to jump hoops here to make sure that we
                 * process any buffers after the sleep, before we dounmount()
                 */
                if (gotsig) {
                        gotsig = 0;
                        if (dounmount(mp, 0, 0) != 0) {
                                KKASSERT(td->td_proc);
                                lwkt_gettoken(&td->td_proc->p_token);
                                sig = CURSIG(td->td_lwp);
                                if (sig) {
                                        spin_lock(&td->td_lwp->lwp_spin);
                                        lwp_delsig(td->td_lwp, sig, 1);
                                        spin_unlock(&td->td_lwp->lwp_spin);
                                }
                                lwkt_reltoken(&td->td_proc->p_token);
                        }
                }
                else if (tsleep((caddr_t)mfsp, PCATCH, "mfsidl", 0))
                        gotsig++;       /* try to unmount in next pass */
        }
        PRELE(curproc);
        if (mfsp->mfs_dev) {
                destroy_dev(mfsp->mfs_dev);
                mfsp->mfs_dev = NULL;
        }
        kfree(mfsp, M_MFSNODE);
        return (EMOUNTEXIT);
}

/*
 * Get file system statistics.
 */
static int
mfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
{
        int error;

        error = ffs_statfs(mp, sbp, cred);
        sbp->f_type = mp->mnt_vfc->vfc_typenum;
        return (error);
}

/*
 * Memory based filesystem initialization.
 */
static int
mfs_init(struct vfsconf *vfsp)
{
        return (0);
}

/*
 * Memory file system I/O.
 *
 * Trivial on the HP since buffer has already been mapping into KVA space.
 *
 * Read and Write are handled with a simple copyin and copyout.
 *
 * We also partially support VOP_FREEBLKS().  We can't implement
 * completely -- for example, on fragments or inode metadata, but we can
 * implement it for page-aligned requests.
 */
static void
mfs_doio(struct bio *bio, struct mfsnode *mfsp)
{
        struct buf *bp = bio->bio_buf;
        caddr_t base = mfsp->mfs_baseoff + bio->bio_offset;
        int bytes;

        switch(bp->b_cmd) {
        case BUF_CMD_FREEBLKS:
                /*
                 * Implement FREEBLKS, which allows the filesystem to tell
                 * a block device when blocks are no longer needed (like when
                 * a file is deleted).  We use the hook to MADV_FREE the VM.
                 * This makes an MFS filesystem work as well or better then
                 * a sun-style swap-mounted filesystem.
                 */
                bytes = bp->b_bcount;

                if ((vm_offset_t)base & PAGE_MASK) {
                        int n = PAGE_SIZE - ((vm_offset_t)base & PAGE_MASK);
                        bytes -= n;
                        base += n;
                }
                if (bytes > 0) {
                        struct madvise_args uap;

                        bytes &= ~PAGE_MASK;
                        if (bytes != 0) {
                                struct sysmsg sysmsg;

                                bzero(&sysmsg, sizeof(sysmsg));
                                bzero(&uap, sizeof(uap));
                                uap.addr  = base;
                                uap.len   = bytes;
                                uap.behav = MADV_FREE;
                                sys_madvise(&sysmsg, &uap);
                        }
                }
                bp->b_error = 0;
                break;
        case BUF_CMD_READ:
                /*
                 * Read data from our 'memory' disk
                 */
                bp->b_error = copyin(base, bp->b_data, bp->b_bcount);
                break;
        case BUF_CMD_WRITE:
                /*
                 * Write data to our 'memory' disk
                 */
                bp->b_error = copyout(bp->b_data, base, bp->b_bcount);
                break;
        default:
                panic("mfs: bad b_cmd %d", bp->b_cmd);
        }
        if (bp->b_error)
                bp->b_flags |= B_ERROR;
        biodone(bio);
}