vm: fix a null dereference on out-of-memory

[minix.git] / sys / ufs / lfs / lfs_vnops.c

/*      $NetBSD: lfs_vnops.c,v 1.238 2011/09/20 14:01:33 chs Exp $      */

/*-
 * Copyright (c) 1999, 2000, 2001, 2002, 2003 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Konrad E. Schroder <perseant@hhhh.org>.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */
/*
 * Copyright (c) 1986, 1989, 1991, 1993, 1995
 *      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.
 *
 *      @(#)lfs_vnops.c 8.13 (Berkeley) 6/10/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: lfs_vnops.c,v 1.238 2011/09/20 14:01:33 chs Exp $");

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/resourcevar.h>
#include <sys/kernel.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/pool.h>
#include <sys/signalvar.h>
#include <sys/kauth.h>
#include <sys/syslog.h>
#include <sys/fstrans.h>

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

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

#include <uvm/uvm.h>
#include <uvm/uvm_pmap.h>
#include <uvm/uvm_stat.h>
#include <uvm/uvm_pager.h>

#include <ufs/lfs/lfs.h>
#include <ufs/lfs/lfs_extern.h>

extern pid_t lfs_writer_daemon;
int lfs_ignore_lazy_sync = 1;

/* Global vfs data structures for lfs. */
int (**lfs_vnodeop_p)(void *);
const struct vnodeopv_entry_desc lfs_vnodeop_entries[] = {
        { &vop_default_desc, vn_default_error },
        { &vop_lookup_desc, ufs_lookup },               /* lookup */
        { &vop_create_desc, lfs_create },               /* create */
        { &vop_whiteout_desc, ufs_whiteout },           /* whiteout */
        { &vop_mknod_desc, lfs_mknod },                 /* mknod */
        { &vop_open_desc, ufs_open },                   /* open */
        { &vop_close_desc, lfs_close },                 /* close */
        { &vop_access_desc, ufs_access },               /* access */
        { &vop_getattr_desc, lfs_getattr },             /* getattr */
        { &vop_setattr_desc, lfs_setattr },             /* setattr */
        { &vop_read_desc, lfs_read },                   /* read */
        { &vop_write_desc, lfs_write },                 /* write */
        { &vop_ioctl_desc, ufs_ioctl },                 /* ioctl */
        { &vop_fcntl_desc, lfs_fcntl },                 /* fcntl */
        { &vop_poll_desc, ufs_poll },                   /* poll */
        { &vop_kqfilter_desc, genfs_kqfilter },         /* kqfilter */
        { &vop_revoke_desc, ufs_revoke },               /* revoke */
        { &vop_mmap_desc, lfs_mmap },                   /* mmap */
        { &vop_fsync_desc, lfs_fsync },                 /* fsync */
        { &vop_seek_desc, ufs_seek },                   /* seek */
        { &vop_remove_desc, lfs_remove },               /* remove */
        { &vop_link_desc, lfs_link },                   /* link */
        { &vop_rename_desc, lfs_rename },               /* rename */
        { &vop_mkdir_desc, lfs_mkdir },                 /* mkdir */
        { &vop_rmdir_desc, lfs_rmdir },                 /* rmdir */
        { &vop_symlink_desc, lfs_symlink },             /* symlink */
        { &vop_readdir_desc, ufs_readdir },             /* readdir */
        { &vop_readlink_desc, ufs_readlink },           /* readlink */
        { &vop_abortop_desc, ufs_abortop },             /* abortop */
        { &vop_inactive_desc, lfs_inactive },           /* inactive */
        { &vop_reclaim_desc, lfs_reclaim },             /* reclaim */
        { &vop_lock_desc, ufs_lock },                   /* lock */
        { &vop_unlock_desc, ufs_unlock },               /* unlock */
        { &vop_bmap_desc, ufs_bmap },                   /* bmap */
        { &vop_strategy_desc, lfs_strategy },           /* strategy */
        { &vop_print_desc, ufs_print },                 /* print */
        { &vop_islocked_desc, ufs_islocked },           /* islocked */
        { &vop_pathconf_desc, ufs_pathconf },           /* pathconf */
        { &vop_advlock_desc, ufs_advlock },             /* advlock */
        { &vop_bwrite_desc, lfs_bwrite },               /* bwrite */
        { &vop_getpages_desc, lfs_getpages },           /* getpages */
        { &vop_putpages_desc, lfs_putpages },           /* putpages */
        { NULL, NULL }
};
const struct vnodeopv_desc lfs_vnodeop_opv_desc =
        { &lfs_vnodeop_p, lfs_vnodeop_entries };

int (**lfs_specop_p)(void *);
const struct vnodeopv_entry_desc lfs_specop_entries[] = {
        { &vop_default_desc, vn_default_error },
        { &vop_lookup_desc, spec_lookup },              /* lookup */
        { &vop_create_desc, spec_create },              /* create */
        { &vop_mknod_desc, spec_mknod },                /* mknod */
        { &vop_open_desc, spec_open },                  /* open */
        { &vop_close_desc, lfsspec_close },             /* close */
        { &vop_access_desc, ufs_access },               /* access */
        { &vop_getattr_desc, lfs_getattr },             /* getattr */
        { &vop_setattr_desc, lfs_setattr },             /* setattr */
        { &vop_read_desc, ufsspec_read },               /* read */
        { &vop_write_desc, ufsspec_write },             /* write */
        { &vop_ioctl_desc, spec_ioctl },                /* ioctl */
        { &vop_fcntl_desc, ufs_fcntl },                 /* fcntl */
        { &vop_poll_desc, spec_poll },                  /* poll */
        { &vop_kqfilter_desc, spec_kqfilter },          /* kqfilter */
        { &vop_revoke_desc, spec_revoke },              /* revoke */
        { &vop_mmap_desc, spec_mmap },                  /* mmap */
        { &vop_fsync_desc, spec_fsync },                /* fsync */
        { &vop_seek_desc, spec_seek },                  /* seek */
        { &vop_remove_desc, spec_remove },              /* remove */
        { &vop_link_desc, spec_link },                  /* link */
        { &vop_rename_desc, spec_rename },              /* rename */
        { &vop_mkdir_desc, spec_mkdir },                /* mkdir */
        { &vop_rmdir_desc, spec_rmdir },                /* rmdir */
        { &vop_symlink_desc, spec_symlink },            /* symlink */
        { &vop_readdir_desc, spec_readdir },            /* readdir */
        { &vop_readlink_desc, spec_readlink },          /* readlink */
        { &vop_abortop_desc, spec_abortop },            /* abortop */
        { &vop_inactive_desc, lfs_inactive },           /* inactive */
        { &vop_reclaim_desc, lfs_reclaim },             /* reclaim */
        { &vop_lock_desc, ufs_lock },                   /* lock */
        { &vop_unlock_desc, ufs_unlock },               /* unlock */
        { &vop_bmap_desc, spec_bmap },                  /* bmap */
        { &vop_strategy_desc, spec_strategy },          /* strategy */
        { &vop_print_desc, ufs_print },                 /* print */
        { &vop_islocked_desc, ufs_islocked },           /* islocked */
        { &vop_pathconf_desc, spec_pathconf },          /* pathconf */
        { &vop_advlock_desc, spec_advlock },            /* advlock */
        { &vop_bwrite_desc, vn_bwrite },                /* bwrite */
        { &vop_getpages_desc, spec_getpages },          /* getpages */
        { &vop_putpages_desc, spec_putpages },          /* putpages */
        { NULL, NULL }
};
const struct vnodeopv_desc lfs_specop_opv_desc =
        { &lfs_specop_p, lfs_specop_entries };

int (**lfs_fifoop_p)(void *);
const struct vnodeopv_entry_desc lfs_fifoop_entries[] = {
        { &vop_default_desc, vn_default_error },
        { &vop_lookup_desc, vn_fifo_bypass },           /* lookup */
        { &vop_create_desc, vn_fifo_bypass },           /* create */
        { &vop_mknod_desc, vn_fifo_bypass },            /* mknod */
        { &vop_open_desc, vn_fifo_bypass },             /* open */
        { &vop_close_desc, lfsfifo_close },             /* close */
        { &vop_access_desc, ufs_access },               /* access */
        { &vop_getattr_desc, lfs_getattr },             /* getattr */
        { &vop_setattr_desc, lfs_setattr },             /* setattr */
        { &vop_read_desc, ufsfifo_read },               /* read */
        { &vop_write_desc, ufsfifo_write },             /* write */
        { &vop_ioctl_desc, vn_fifo_bypass },            /* ioctl */
        { &vop_fcntl_desc, ufs_fcntl },                 /* fcntl */
        { &vop_poll_desc, vn_fifo_bypass },             /* poll */
        { &vop_kqfilter_desc, vn_fifo_bypass },         /* kqfilter */
        { &vop_revoke_desc, vn_fifo_bypass },           /* revoke */
        { &vop_mmap_desc, vn_fifo_bypass },             /* mmap */
        { &vop_fsync_desc, vn_fifo_bypass },            /* fsync */
        { &vop_seek_desc, vn_fifo_bypass },             /* seek */
        { &vop_remove_desc, vn_fifo_bypass },           /* remove */
        { &vop_link_desc, vn_fifo_bypass },             /* link */
        { &vop_rename_desc, vn_fifo_bypass },           /* rename */
        { &vop_mkdir_desc, vn_fifo_bypass },            /* mkdir */
        { &vop_rmdir_desc, vn_fifo_bypass },            /* rmdir */
        { &vop_symlink_desc, vn_fifo_bypass },          /* symlink */
        { &vop_readdir_desc, vn_fifo_bypass },          /* readdir */
        { &vop_readlink_desc, vn_fifo_bypass },         /* readlink */
        { &vop_abortop_desc, vn_fifo_bypass },          /* abortop */
        { &vop_inactive_desc, lfs_inactive },           /* inactive */
        { &vop_reclaim_desc, lfs_reclaim },             /* reclaim */
        { &vop_lock_desc, ufs_lock },                   /* lock */
        { &vop_unlock_desc, ufs_unlock },               /* unlock */
        { &vop_bmap_desc, vn_fifo_bypass },             /* bmap */
        { &vop_strategy_desc, vn_fifo_bypass },         /* strategy */
        { &vop_print_desc, ufs_print },                 /* print */
        { &vop_islocked_desc, ufs_islocked },           /* islocked */
        { &vop_pathconf_desc, vn_fifo_bypass },         /* pathconf */
        { &vop_advlock_desc, vn_fifo_bypass },          /* advlock */
        { &vop_bwrite_desc, lfs_bwrite },               /* bwrite */
        { &vop_putpages_desc, vn_fifo_bypass },         /* putpages */
        { NULL, NULL }
};
const struct vnodeopv_desc lfs_fifoop_opv_desc =
        { &lfs_fifoop_p, lfs_fifoop_entries };

static int check_dirty(struct lfs *, struct vnode *, off_t, off_t, off_t, int, int, struct vm_page **);

#define LFS_READWRITE
#include <ufs/ufs/ufs_readwrite.c>
#undef  LFS_READWRITE

/*
 * Synch an open file.
 */
/* ARGSUSED */
int
lfs_fsync(void *v)
{
        struct vop_fsync_args /* {
                struct vnode *a_vp;
                kauth_cred_t a_cred;
                int a_flags;
                off_t offlo;
                off_t offhi;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        int error, wait;
        struct inode *ip = VTOI(vp);
        struct lfs *fs = ip->i_lfs;

        /* If we're mounted read-only, don't try to sync. */
        if (fs->lfs_ronly)
                return 0;

        /* If a removed vnode is being cleaned, no need to sync here. */
        if ((ap->a_flags & FSYNC_RECLAIM) != 0 && ip->i_mode == 0)
                return 0;

        /*
         * Trickle sync simply adds this vnode to the pager list, as if
         * the pagedaemon had requested a pageout.
         */
        if (ap->a_flags & FSYNC_LAZY) {
                if (lfs_ignore_lazy_sync == 0) {
                        mutex_enter(&lfs_lock);
                        if (!(ip->i_flags & IN_PAGING)) {
                                ip->i_flags |= IN_PAGING;
                                TAILQ_INSERT_TAIL(&fs->lfs_pchainhd, ip,
                                                  i_lfs_pchain);
                        }
                        wakeup(&lfs_writer_daemon);
                        mutex_exit(&lfs_lock);
                }
                return 0;
        }

        /*
         * If a vnode is bring cleaned, flush it out before we try to
         * reuse it.  This prevents the cleaner from writing files twice
         * in the same partial segment, causing an accounting underflow.
         */
        if (ap->a_flags & FSYNC_RECLAIM && ip->i_flags & IN_CLEANING) {
                lfs_vflush(vp);
        }

        wait = (ap->a_flags & FSYNC_WAIT);
        do {
                mutex_enter(vp->v_interlock);
                error = VOP_PUTPAGES(vp, trunc_page(ap->a_offlo),
                                     round_page(ap->a_offhi),
                                     PGO_CLEANIT | (wait ? PGO_SYNCIO : 0));
                if (error == EAGAIN) {
                        mutex_enter(&lfs_lock);
                        mtsleep(&fs->lfs_avail, PCATCH | PUSER, "lfs_fsync",
                                hz / 100 + 1, &lfs_lock);
                        mutex_exit(&lfs_lock);
                }
        } while (error == EAGAIN);
        if (error)
                return error;

        if ((ap->a_flags & FSYNC_DATAONLY) == 0)
                error = lfs_update(vp, NULL, NULL, wait ? UPDATE_WAIT : 0);

        if (error == 0 && ap->a_flags & FSYNC_CACHE) {
                int l = 0;
                error = VOP_IOCTL(ip->i_devvp, DIOCCACHESYNC, &l, FWRITE,
                                  curlwp->l_cred);
        }
        if (wait && !VPISEMPTY(vp))
                LFS_SET_UINO(ip, IN_MODIFIED);

        return error;
}

/*
 * Take IN_ADIROP off, then call ufs_inactive.
 */
int
lfs_inactive(void *v)
{
        struct vop_inactive_args /* {
                struct vnode *a_vp;
        } */ *ap = v;

        lfs_unmark_vnode(ap->a_vp);

        /*
         * The Ifile is only ever inactivated on unmount.
         * Streamline this process by not giving it more dirty blocks.
         */
        if (VTOI(ap->a_vp)->i_number == LFS_IFILE_INUM) {
                mutex_enter(&lfs_lock);
                LFS_CLR_UINO(VTOI(ap->a_vp), IN_ALLMOD);
                mutex_exit(&lfs_lock);
                VOP_UNLOCK(ap->a_vp);
                return 0;
        }

        return ufs_inactive(v);
}

/*
 * These macros are used to bracket UFS directory ops, so that we can
 * identify all the pages touched during directory ops which need to
 * be ordered and flushed atomically, so that they may be recovered.
 *
 * Because we have to mark nodes VU_DIROP in order to prevent
 * the cache from reclaiming them while a dirop is in progress, we must
 * also manage the number of nodes so marked (otherwise we can run out).
 * We do this by setting lfs_dirvcount to the number of marked vnodes; it
 * is decremented during segment write, when VU_DIROP is taken off.
 */
#define MARK_VNODE(vp)                  lfs_mark_vnode(vp)
#define UNMARK_VNODE(vp)                lfs_unmark_vnode(vp)
#define SET_DIROP_CREATE(dvp, vpp)      lfs_set_dirop_create((dvp), (vpp))
#define SET_DIROP_REMOVE(dvp, vp)       lfs_set_dirop((dvp), (vp))
static int lfs_set_dirop_create(struct vnode *, struct vnode **);
static int lfs_set_dirop(struct vnode *, struct vnode *);

static int
lfs_set_dirop(struct vnode *dvp, struct vnode *vp)
{
        struct lfs *fs;
        int error;

        KASSERT(VOP_ISLOCKED(dvp));
        KASSERT(vp == NULL || VOP_ISLOCKED(vp));

        fs = VTOI(dvp)->i_lfs;

        ASSERT_NO_SEGLOCK(fs);
        /*
         * LFS_NRESERVE calculates direct and indirect blocks as well
         * as an inode block; an overestimate in most cases.
         */
        if ((error = lfs_reserve(fs, dvp, vp, LFS_NRESERVE(fs))) != 0)
                return (error);

    restart:
        mutex_enter(&lfs_lock);
        if (fs->lfs_dirops == 0) {
                mutex_exit(&lfs_lock);
                lfs_check(dvp, LFS_UNUSED_LBN, 0);
                mutex_enter(&lfs_lock);
        }
        while (fs->lfs_writer) {
                error = mtsleep(&fs->lfs_dirops, (PRIBIO + 1) | PCATCH,
                    "lfs_sdirop", 0, &lfs_lock);
                if (error == EINTR) {
                        mutex_exit(&lfs_lock);
                        goto unreserve;
                }
        }
        if (lfs_dirvcount > LFS_MAX_DIROP && fs->lfs_dirops == 0) {
                wakeup(&lfs_writer_daemon);
                mutex_exit(&lfs_lock);
                preempt();
                goto restart;
        }

        if (lfs_dirvcount > LFS_MAX_DIROP) {
                mutex_exit(&lfs_lock);
                DLOG((DLOG_DIROP, "lfs_set_dirop: sleeping with dirops=%d, "
                      "dirvcount=%d\n", fs->lfs_dirops, lfs_dirvcount));
                if ((error = mtsleep(&lfs_dirvcount,
                    PCATCH | PUSER | PNORELOCK, "lfs_maxdirop", 0,
                    &lfs_lock)) != 0) {
                        goto unreserve;
                }
                goto restart;
        }

        ++fs->lfs_dirops;
        fs->lfs_doifile = 1;
        mutex_exit(&lfs_lock);

        /* Hold a reference so SET_ENDOP will be happy */
        vref(dvp);
        if (vp) {
                vref(vp);
                MARK_VNODE(vp);
        }

        MARK_VNODE(dvp);
        return 0;

  unreserve:
        lfs_reserve(fs, dvp, vp, -LFS_NRESERVE(fs));
        return error;
}

/*
 * Get a new vnode *before* adjusting the dirop count, to avoid a deadlock
 * in getnewvnode(), if we have a stacked filesystem mounted on top
 * of us.
 *
 * NB: this means we have to clear the new vnodes on error.  Fortunately
 * SET_ENDOP is there to do that for us.
 */
static int
lfs_set_dirop_create(struct vnode *dvp, struct vnode **vpp)
{
        int error;
        struct lfs *fs;

        fs = VFSTOUFS(dvp->v_mount)->um_lfs;
        ASSERT_NO_SEGLOCK(fs);
        if (fs->lfs_ronly)
                return EROFS;
        if (vpp == NULL) {
                return lfs_set_dirop(dvp, NULL);
        }
        error = getnewvnode(VT_LFS, dvp->v_mount, lfs_vnodeop_p, NULL, vpp);
        if (error) {
                DLOG((DLOG_ALLOC, "lfs_set_dirop_create: dvp %p error %d\n",
                      dvp, error));
                return error;
        }
        if ((error = lfs_set_dirop(dvp, NULL)) != 0) {
                ungetnewvnode(*vpp);
                *vpp = NULL;
                return error;
        }
        return 0;
}

#define SET_ENDOP_BASE(fs, dvp, str)                                    \
        do {                                                            \
                mutex_enter(&lfs_lock);                         \
                --(fs)->lfs_dirops;                                     \
                if (!(fs)->lfs_dirops) {                                \
                        if ((fs)->lfs_nadirop) {                        \
                                panic("SET_ENDOP: %s: no dirops but "   \
                                        " nadirop=%d", (str),           \
                                        (fs)->lfs_nadirop);             \
                        }                                               \
                        wakeup(&(fs)->lfs_writer);                      \
                        mutex_exit(&lfs_lock);                          \
                        lfs_check((dvp), LFS_UNUSED_LBN, 0);            \
                } else                                                  \
                        mutex_exit(&lfs_lock);                          \
        } while(0)
#define SET_ENDOP_CREATE(fs, dvp, nvpp, str)                            \
        do {                                                            \
                UNMARK_VNODE(dvp);                                      \
                if (nvpp && *nvpp)                                      \
                        UNMARK_VNODE(*nvpp);                            \
                /* Check for error return to stem vnode leakage */      \
                if (nvpp && *nvpp && !((*nvpp)->v_uflag & VU_DIROP))    \
                        ungetnewvnode(*(nvpp));                         \
                SET_ENDOP_BASE((fs), (dvp), (str));                     \
                lfs_reserve((fs), (dvp), NULL, -LFS_NRESERVE(fs));      \
                vrele(dvp);                                             \
        } while(0)
#define SET_ENDOP_CREATE_AP(ap, str)                                    \
        SET_ENDOP_CREATE(VTOI((ap)->a_dvp)->i_lfs, (ap)->a_dvp,         \
                         (ap)->a_vpp, (str))
#define SET_ENDOP_REMOVE(fs, dvp, ovp, str)                             \
        do {                                                            \
                UNMARK_VNODE(dvp);                                      \
                if (ovp)                                                \
                        UNMARK_VNODE(ovp);                              \
                SET_ENDOP_BASE((fs), (dvp), (str));                     \
                lfs_reserve((fs), (dvp), (ovp), -LFS_NRESERVE(fs));     \
                vrele(dvp);                                             \
                if (ovp)                                                \
                        vrele(ovp);                                     \
        } while(0)

void
lfs_mark_vnode(struct vnode *vp)
{
        struct inode *ip = VTOI(vp);
        struct lfs *fs = ip->i_lfs;

        mutex_enter(&lfs_lock);
        if (!(ip->i_flag & IN_ADIROP)) {
                if (!(vp->v_uflag & VU_DIROP)) {
                        mutex_enter(vp->v_interlock);
                        (void)lfs_vref(vp);
                        ++lfs_dirvcount;
                        ++fs->lfs_dirvcount;
                        TAILQ_INSERT_TAIL(&fs->lfs_dchainhd, ip, i_lfs_dchain);
                        vp->v_uflag |= VU_DIROP;
                }
                ++fs->lfs_nadirop;
                ip->i_flag |= IN_ADIROP;
        } else
                KASSERT(vp->v_uflag & VU_DIROP);
        mutex_exit(&lfs_lock);
}

void
lfs_unmark_vnode(struct vnode *vp)
{
        struct inode *ip = VTOI(vp);

        if (ip && (ip->i_flag & IN_ADIROP)) {
                KASSERT(vp->v_uflag & VU_DIROP);
                mutex_enter(&lfs_lock);
                --ip->i_lfs->lfs_nadirop;
                mutex_exit(&lfs_lock);
                ip->i_flag &= ~IN_ADIROP;
        }
}

int
lfs_symlink(void *v)
{
        struct vop_symlink_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
                struct vattr *a_vap;
                char *a_target;
        } */ *ap = v;
        int error;

        if ((error = SET_DIROP_CREATE(ap->a_dvp, ap->a_vpp)) != 0) {
                vput(ap->a_dvp);
                return error;
        }
        error = ufs_symlink(ap);
        SET_ENDOP_CREATE_AP(ap, "symlink");
        return (error);
}

int
lfs_mknod(void *v)
{
        struct vop_mknod_args   /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
                struct vattr *a_vap;
        } */ *ap = v;
        struct vattr *vap = ap->a_vap;
        struct vnode **vpp = ap->a_vpp;
        struct inode *ip;
        int error;
        struct mount    *mp;
        ino_t           ino;
        struct ufs_lookup_results *ulr;

        /* XXX should handle this material another way */
        ulr = &VTOI(ap->a_dvp)->i_crap;
        UFS_CHECK_CRAPCOUNTER(VTOI(ap->a_dvp));

        if ((error = SET_DIROP_CREATE(ap->a_dvp, ap->a_vpp)) != 0) {
                vput(ap->a_dvp);
                return error;
        }
        error = ufs_makeinode(MAKEIMODE(vap->va_type, vap->va_mode),
                              ap->a_dvp, ulr, vpp, ap->a_cnp);

        /* Either way we're done with the dirop at this point */
        SET_ENDOP_CREATE_AP(ap, "mknod");

        if (error)
                return (error);

        ip = VTOI(*vpp);
        mp  = (*vpp)->v_mount;
        ino = ip->i_number;
        ip->i_flag |= IN_ACCESS | IN_CHANGE | IN_UPDATE;
        if (vap->va_rdev != VNOVAL) {
                /*
                 * Want to be able to use this to make badblock
                 * inodes, so don't truncate the dev number.
                 */
#if 0
                ip->i_ffs1_rdev = ufs_rw32(vap->va_rdev,
                                           UFS_MPNEEDSWAP((*vpp)->v_mount));
#else
                ip->i_ffs1_rdev = vap->va_rdev;
#endif
        }

        /*
         * Call fsync to write the vnode so that we don't have to deal with
         * flushing it when it's marked VU_DIROP|VI_XLOCK.
         *
         * XXX KS - If we can't flush we also can't call vgone(), so must
         * return.  But, that leaves this vnode in limbo, also not good.
         * Can this ever happen (barring hardware failure)?
         */
        if ((error = VOP_FSYNC(*vpp, NOCRED, FSYNC_WAIT, 0, 0)) != 0) {
                panic("lfs_mknod: couldn't fsync (ino %llu)",
                      (unsigned long long)ino);
                /* return (error); */
        }
        /*
         * Remove vnode so that it will be reloaded by VFS_VGET and
         * checked to see if it is an alias of an existing entry in
         * the inode cache.
         */
        /* Used to be vput, but that causes us to call VOP_INACTIVE twice. */

        VOP_UNLOCK(*vpp);
        (*vpp)->v_type = VNON;
        vgone(*vpp);
        error = VFS_VGET(mp, ino, vpp);

        if (error != 0) {
                *vpp = NULL;
                return (error);
        }
        return (0);
}

int
lfs_create(void *v)
{
        struct vop_create_args  /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
                struct vattr *a_vap;
        } */ *ap = v;
        int error;

        if ((error = SET_DIROP_CREATE(ap->a_dvp, ap->a_vpp)) != 0) {
                vput(ap->a_dvp);
                return error;
        }
        error = ufs_create(ap);
        SET_ENDOP_CREATE_AP(ap, "create");
        return (error);
}

int
lfs_mkdir(void *v)
{
        struct vop_mkdir_args   /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
                struct vattr *a_vap;
        } */ *ap = v;
        int error;

        if ((error = SET_DIROP_CREATE(ap->a_dvp, ap->a_vpp)) != 0) {
                vput(ap->a_dvp);
                return error;
        }
        error = ufs_mkdir(ap);
        SET_ENDOP_CREATE_AP(ap, "mkdir");
        return (error);
}

int
lfs_remove(void *v)
{
        struct vop_remove_args  /* {
                struct vnode *a_dvp;
                struct vnode *a_vp;
                struct componentname *a_cnp;
        } */ *ap = v;
        struct vnode *dvp, *vp;
        struct inode *ip;
        int error;

        dvp = ap->a_dvp;
        vp = ap->a_vp;
        ip = VTOI(vp);
        if ((error = SET_DIROP_REMOVE(dvp, vp)) != 0) {
                if (dvp == vp)
                        vrele(vp);
                else
                        vput(vp);
                vput(dvp);
                return error;
        }
        error = ufs_remove(ap);
        if (ip->i_nlink == 0)
                lfs_orphan(ip->i_lfs, ip->i_number);
        SET_ENDOP_REMOVE(ip->i_lfs, dvp, ap->a_vp, "remove");
        return (error);
}

int
lfs_rmdir(void *v)
{
        struct vop_rmdir_args   /* {
                struct vnodeop_desc *a_desc;
                struct vnode *a_dvp;
                struct vnode *a_vp;
                struct componentname *a_cnp;
        } */ *ap = v;
        struct vnode *vp;
        struct inode *ip;
        int error;

        vp = ap->a_vp;
        ip = VTOI(vp);
        if ((error = SET_DIROP_REMOVE(ap->a_dvp, ap->a_vp)) != 0) {
                if (ap->a_dvp == vp)
                        vrele(ap->a_dvp);
                else
                        vput(ap->a_dvp);
                vput(vp);
                return error;
        }
        error = ufs_rmdir(ap);
        if (ip->i_nlink == 0)
                lfs_orphan(ip->i_lfs, ip->i_number);
        SET_ENDOP_REMOVE(ip->i_lfs, ap->a_dvp, ap->a_vp, "rmdir");
        return (error);
}

int
lfs_link(void *v)
{
        struct vop_link_args    /* {
                struct vnode *a_dvp;
                struct vnode *a_vp;
                struct componentname *a_cnp;
        } */ *ap = v;
        int error;
        struct vnode **vpp = NULL;

        if ((error = SET_DIROP_CREATE(ap->a_dvp, vpp)) != 0) {
                vput(ap->a_dvp);
                return error;
        }
        error = ufs_link(ap);
        SET_ENDOP_CREATE(VTOI(ap->a_dvp)->i_lfs, ap->a_dvp, vpp, "link");
        return (error);
}

int
lfs_rename(void *v)
{
        struct vop_rename_args  /* {
                struct vnode *a_fdvp;
                struct vnode *a_fvp;
                struct componentname *a_fcnp;
                struct vnode *a_tdvp;
                struct vnode *a_tvp;
                struct componentname *a_tcnp;
        } */ *ap = v;
        struct vnode *tvp, *fvp, *tdvp, *fdvp;
        struct componentname *tcnp, *fcnp;
        int error;
        struct lfs *fs;

        fs = VTOI(ap->a_fdvp)->i_lfs;
        tvp = ap->a_tvp;
        tdvp = ap->a_tdvp;
        tcnp = ap->a_tcnp;
        fvp = ap->a_fvp;
        fdvp = ap->a_fdvp;
        fcnp = ap->a_fcnp;

        /*
         * Check for cross-device rename.
         * If it is, we don't want to set dirops, just error out.
         * (In particular note that MARK_VNODE(tdvp) will DTWT on
         * a cross-device rename.)
         *
         * Copied from ufs_rename.
         */
        if ((fvp->v_mount != tdvp->v_mount) ||
            (tvp && (fvp->v_mount != tvp->v_mount))) {
                error = EXDEV;
                goto errout;
        }

        /*
         * Check to make sure we're not renaming a vnode onto itself
         * (deleting a hard link by renaming one name onto another);
         * if we are we can't recursively call VOP_REMOVE since that
         * would leave us with an unaccounted-for number of live dirops.
         *
         * Inline the relevant section of ufs_rename here, *before*
         * calling SET_DIROP_REMOVE.
         */
        if (tvp && ((VTOI(tvp)->i_flags & (IMMUTABLE | APPEND)) ||
                    (VTOI(tdvp)->i_flags & APPEND))) {
                error = EPERM;
                goto errout;
        }
        if (fvp == tvp) {
                if (fvp->v_type == VDIR) {
                        error = EINVAL;
                        goto errout;
                }

                /* Release destination completely. */
                VOP_ABORTOP(tdvp, tcnp);
                vput(tdvp);
                vput(tvp);

                /* Delete source. */
                vrele(fvp);
                fcnp->cn_flags &= ~(MODMASK);
                fcnp->cn_flags |= LOCKPARENT | LOCKLEAF;
                fcnp->cn_nameiop = DELETE;
                vn_lock(fdvp, LK_EXCLUSIVE | LK_RETRY);
                if ((error = relookup(fdvp, &fvp, fcnp, 0))) {
                        vput(fdvp);
                        return (error);
                }
                return (VOP_REMOVE(fdvp, fvp, fcnp));
        }

        if ((error = SET_DIROP_REMOVE(tdvp, tvp)) != 0)
                goto errout;
        MARK_VNODE(fdvp);
        MARK_VNODE(fvp);

        error = ufs_rename(ap);
        UNMARK_VNODE(fdvp);
        UNMARK_VNODE(fvp);
        SET_ENDOP_REMOVE(fs, tdvp, tvp, "rename");
        return (error);

  errout:
        VOP_ABORTOP(tdvp, ap->a_tcnp); /* XXX, why not in NFS? */
        if (tdvp == tvp)
                vrele(tdvp);
        else
                vput(tdvp);
        if (tvp)
                vput(tvp);
        VOP_ABORTOP(fdvp, ap->a_fcnp); /* XXX, why not in NFS? */
        vrele(fdvp);
        vrele(fvp);
        return (error);
}

/* XXX hack to avoid calling ITIMES in getattr */
int
lfs_getattr(void *v)
{
        struct vop_getattr_args /* {
                struct vnode *a_vp;
                struct vattr *a_vap;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct inode *ip = VTOI(vp);
        struct vattr *vap = ap->a_vap;
        struct lfs *fs = ip->i_lfs;
        /*
         * Copy from inode table
         */
        vap->va_fsid = ip->i_dev;
        vap->va_fileid = ip->i_number;
        vap->va_mode = ip->i_mode & ~IFMT;
        vap->va_nlink = ip->i_nlink;
        vap->va_uid = ip->i_uid;
        vap->va_gid = ip->i_gid;
        vap->va_rdev = (dev_t)ip->i_ffs1_rdev;
        vap->va_size = vp->v_size;
        vap->va_atime.tv_sec = ip->i_ffs1_atime;
        vap->va_atime.tv_nsec = ip->i_ffs1_atimensec;
        vap->va_mtime.tv_sec = ip->i_ffs1_mtime;
        vap->va_mtime.tv_nsec = ip->i_ffs1_mtimensec;
        vap->va_ctime.tv_sec = ip->i_ffs1_ctime;
        vap->va_ctime.tv_nsec = ip->i_ffs1_ctimensec;
        vap->va_flags = ip->i_flags;
        vap->va_gen = ip->i_gen;
        /* this doesn't belong here */
        if (vp->v_type == VBLK)
                vap->va_blocksize = BLKDEV_IOSIZE;
        else if (vp->v_type == VCHR)
                vap->va_blocksize = MAXBSIZE;
        else
                vap->va_blocksize = vp->v_mount->mnt_stat.f_iosize;
        vap->va_bytes = fsbtob(fs, (u_quad_t)ip->i_lfs_effnblks);
        vap->va_type = vp->v_type;
        vap->va_filerev = ip->i_modrev;
        return (0);
}

/*
 * Check to make sure the inode blocks won't choke the buffer
 * cache, then call ufs_setattr as usual.
 */
int
lfs_setattr(void *v)
{
        struct vop_setattr_args /* {
                struct vnode *a_vp;
                struct vattr *a_vap;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;

        lfs_check(vp, LFS_UNUSED_LBN, 0);
        return ufs_setattr(v);
}

/*
 * Release the block we hold on lfs_newseg wrapping.  Called on file close,
 * or explicitly from LFCNWRAPGO.  Called with the interlock held.
 */
static int
lfs_wrapgo(struct lfs *fs, struct inode *ip, int waitfor)
{
        if (fs->lfs_stoplwp != curlwp)
                return EBUSY;

        fs->lfs_stoplwp = NULL;
        cv_signal(&fs->lfs_stopcv);

        KASSERT(fs->lfs_nowrap > 0);
        if (fs->lfs_nowrap <= 0) {
                return 0;
        }

        if (--fs->lfs_nowrap == 0) {
                log(LOG_NOTICE, "%s: re-enabled log wrap\n", fs->lfs_fsmnt);
                wakeup(&fs->lfs_wrappass);
                lfs_wakeup_cleaner(fs);
        }
        if (waitfor) {
                mtsleep(&fs->lfs_nextseg, PCATCH | PUSER, "segment",
                    0, &lfs_lock);
        }

        return 0;
}

/*
 * Close called
 */
/* ARGSUSED */
int
lfs_close(void *v)
{
        struct vop_close_args /* {
                struct vnode *a_vp;
                int  a_fflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct inode *ip = VTOI(vp);
        struct lfs *fs = ip->i_lfs;

        if ((ip->i_number == ROOTINO || ip->i_number == LFS_IFILE_INUM) &&
            fs->lfs_stoplwp == curlwp) {
                mutex_enter(&lfs_lock);
                log(LOG_NOTICE, "lfs_close: releasing log wrap control\n");
                lfs_wrapgo(fs, ip, 0);
                mutex_exit(&lfs_lock);
        }

        if (vp == ip->i_lfs->lfs_ivnode &&
            vp->v_mount->mnt_iflag & IMNT_UNMOUNT)
                return 0;

        if (vp->v_usecount > 1 && vp != ip->i_lfs->lfs_ivnode) {
                LFS_ITIMES(ip, NULL, NULL, NULL);
        }
        return (0);
}

/*
 * Close wrapper for special devices.
 *
 * Update the times on the inode then do device close.
 */
int
lfsspec_close(void *v)
{
        struct vop_close_args /* {
                struct vnode    *a_vp;
                int             a_fflag;
                kauth_cred_t    a_cred;
        } */ *ap = v;
        struct vnode    *vp;
        struct inode    *ip;

        vp = ap->a_vp;
        ip = VTOI(vp);
        if (vp->v_usecount > 1) {
                LFS_ITIMES(ip, NULL, NULL, NULL);
        }
        return (VOCALL (spec_vnodeop_p, VOFFSET(vop_close), ap));
}

/*
 * Close wrapper for fifo's.
 *
 * Update the times on the inode then do device close.
 */
int
lfsfifo_close(void *v)
{
        struct vop_close_args /* {
                struct vnode    *a_vp;
                int             a_fflag;
                kauth_cred_     a_cred;
        } */ *ap = v;
        struct vnode    *vp;
        struct inode    *ip;

        vp = ap->a_vp;
        ip = VTOI(vp);
        if (ap->a_vp->v_usecount > 1) {
                LFS_ITIMES(ip, NULL, NULL, NULL);
        }
        return (VOCALL (fifo_vnodeop_p, VOFFSET(vop_close), ap));
}

/*
 * Reclaim an inode so that it can be used for other purposes.
 */

int
lfs_reclaim(void *v)
{
        struct vop_reclaim_args /* {
                struct vnode *a_vp;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct inode *ip = VTOI(vp);
        struct lfs *fs = ip->i_lfs;
        int error;

        /*
         * The inode must be freed and updated before being removed
         * from its hash chain.  Other threads trying to gain a hold
         * on the inode will be stalled because it is locked (VI_XLOCK).
         */
        if (ip->i_nlink <= 0 && (vp->v_mount->mnt_flag & MNT_RDONLY) == 0)
                lfs_vfree(vp, ip->i_number, ip->i_omode);

        mutex_enter(&lfs_lock);
        LFS_CLR_UINO(ip, IN_ALLMOD);
        mutex_exit(&lfs_lock);
        if ((error = ufs_reclaim(vp)))
                return (error);

        /*
         * Take us off the paging and/or dirop queues if we were on them.
         * We shouldn't be on them.
         */
        mutex_enter(&lfs_lock);
        if (ip->i_flags & IN_PAGING) {
                log(LOG_WARNING, "%s: reclaimed vnode is IN_PAGING\n",
                    fs->lfs_fsmnt);
                ip->i_flags &= ~IN_PAGING;
                TAILQ_REMOVE(&fs->lfs_pchainhd, ip, i_lfs_pchain);
        }
        if (vp->v_uflag & VU_DIROP) {
                panic("reclaimed vnode is VU_DIROP");
                vp->v_uflag &= ~VU_DIROP;
                TAILQ_REMOVE(&fs->lfs_dchainhd, ip, i_lfs_dchain);
        }
        mutex_exit(&lfs_lock);

        pool_put(&lfs_dinode_pool, ip->i_din.ffs1_din);
        lfs_deregister_all(vp);
        pool_put(&lfs_inoext_pool, ip->inode_ext.lfs);
        ip->inode_ext.lfs = NULL;
        genfs_node_destroy(vp);
        pool_put(&lfs_inode_pool, vp->v_data);
        vp->v_data = NULL;
        return (0);
}

/*
 * Read a block from a storage device.
 * In order to avoid reading blocks that are in the process of being
 * written by the cleaner---and hence are not mutexed by the normal
 * buffer cache / page cache mechanisms---check for collisions before
 * reading.
 *
 * We inline ufs_strategy to make sure that the VOP_BMAP occurs *before*
 * the active cleaner test.
 *
 * XXX This code assumes that lfs_markv makes synchronous checkpoints.
 */
int
lfs_strategy(void *v)
{
        struct vop_strategy_args /* {
                struct vnode *a_vp;
                struct buf *a_bp;
        } */ *ap = v;
        struct buf      *bp;
        struct lfs      *fs;
        struct vnode    *vp;
        struct inode    *ip;
        daddr_t         tbn;
        int             i, sn, error, slept;

        bp = ap->a_bp;
        vp = ap->a_vp;
        ip = VTOI(vp);
        fs = ip->i_lfs;

        /* lfs uses its strategy routine only for read */
        KASSERT(bp->b_flags & B_READ);

        if (vp->v_type == VBLK || vp->v_type == VCHR)
                panic("lfs_strategy: spec");
        KASSERT(bp->b_bcount != 0);
        if (bp->b_blkno == bp->b_lblkno) {
                error = VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
                                 NULL);
                if (error) {
                        bp->b_error = error;
                        bp->b_resid = bp->b_bcount;
                        biodone(bp);
                        return (error);
                }
                if ((long)bp->b_blkno == -1) /* no valid data */
                        clrbuf(bp);
        }
        if ((long)bp->b_blkno < 0) { /* block is not on disk */
                bp->b_resid = bp->b_bcount;
                biodone(bp);
                return (0);
        }

        slept = 1;
        mutex_enter(&lfs_lock);
        while (slept && fs->lfs_seglock) {
                mutex_exit(&lfs_lock);
                /*
                 * Look through list of intervals.
                 * There will only be intervals to look through
                 * if the cleaner holds the seglock.
                 * Since the cleaner is synchronous, we can trust
                 * the list of intervals to be current.
                 */
                tbn = dbtofsb(fs, bp->b_blkno);
                sn = dtosn(fs, tbn);
                slept = 0;
                for (i = 0; i < fs->lfs_cleanind; i++) {
                        if (sn == dtosn(fs, fs->lfs_cleanint[i]) &&
                            tbn >= fs->lfs_cleanint[i]) {
                                DLOG((DLOG_CLEAN,
                                      "lfs_strategy: ino %d lbn %" PRId64
                                      " ind %d sn %d fsb %" PRIx32
                                      " given sn %d fsb %" PRIx64 "\n",
                                      ip->i_number, bp->b_lblkno, i,
                                      dtosn(fs, fs->lfs_cleanint[i]),
                                      fs->lfs_cleanint[i], sn, tbn));
                                DLOG((DLOG_CLEAN,
                                      "lfs_strategy: sleeping on ino %d lbn %"
                                      PRId64 "\n", ip->i_number, bp->b_lblkno));
                                mutex_enter(&lfs_lock);
                                if (LFS_SEGLOCK_HELD(fs) && fs->lfs_iocount) {
                                        /* Cleaner can't wait for itself */
                                        mtsleep(&fs->lfs_iocount,
                                                (PRIBIO + 1) | PNORELOCK,
                                                "clean2", 0,
                                                &lfs_lock);
                                        slept = 1;
                                        break;
                                } else if (fs->lfs_seglock) {
                                        mtsleep(&fs->lfs_seglock,
                                                (PRIBIO + 1) | PNORELOCK,
                                                "clean1", 0,
                                                &lfs_lock);
                                        slept = 1;
                                        break;
                                }
                                mutex_exit(&lfs_lock);
                        }
                }
                mutex_enter(&lfs_lock);
        }
        mutex_exit(&lfs_lock);

        vp = ip->i_devvp;
        VOP_STRATEGY(vp, bp);
        return (0);
}

void
lfs_flush_dirops(struct lfs *fs)
{
        struct inode *ip, *nip;
        struct vnode *vp;
        extern int lfs_dostats;
        struct segment *sp;

        ASSERT_MAYBE_SEGLOCK(fs);
        KASSERT(fs->lfs_nadirop == 0);

        if (fs->lfs_ronly)
                return;

        mutex_enter(&lfs_lock);
        if (TAILQ_FIRST(&fs->lfs_dchainhd) == NULL) {
                mutex_exit(&lfs_lock);
                return;
        } else
                mutex_exit(&lfs_lock);

        if (lfs_dostats)
                ++lfs_stats.flush_invoked;

        /*
         * Inline lfs_segwrite/lfs_writevnodes, but just for dirops.
         * Technically this is a checkpoint (the on-disk state is valid)
         * even though we are leaving out all the file data.
         */
        lfs_imtime(fs);
        lfs_seglock(fs, SEGM_CKP);
        sp = fs->lfs_sp;

        /*
         * lfs_writevnodes, optimized to get dirops out of the way.
         * Only write dirops, and don't flush files' pages, only
         * blocks from the directories.
         *
         * We don't need to vref these files because they are
         * dirops and so hold an extra reference until the
         * segunlock clears them of that status.
         *
         * We don't need to check for IN_ADIROP because we know that
         * no dirops are active.
         *
         */
        mutex_enter(&lfs_lock);
        for (ip = TAILQ_FIRST(&fs->lfs_dchainhd); ip != NULL; ip = nip) {
                nip = TAILQ_NEXT(ip, i_lfs_dchain);
                mutex_exit(&lfs_lock);
                vp = ITOV(ip);

                KASSERT((ip->i_flag & IN_ADIROP) == 0);

                /*
                 * All writes to directories come from dirops; all
                 * writes to files' direct blocks go through the page
                 * cache, which we're not touching.  Reads to files
                 * and/or directories will not be affected by writing
                 * directory blocks inodes and file inodes.  So we don't
                 * really need to lock.  If we don't lock, though,
                 * make sure that we don't clear IN_MODIFIED
                 * unnecessarily.
                 */
                if (vp->v_iflag & VI_XLOCK) {
                        mutex_enter(&lfs_lock);
                        continue;
                }
                /* XXX see below
                 * waslocked = VOP_ISLOCKED(vp);
                 */
                if (vp->v_type != VREG &&
                    ((ip->i_flag & IN_ALLMOD) || !VPISEMPTY(vp))) {
                        lfs_writefile(fs, sp, vp);
                        if (!VPISEMPTY(vp) && !WRITEINPROG(vp) &&
                            !(ip->i_flag & IN_ALLMOD)) {
                                mutex_enter(&lfs_lock);
                                LFS_SET_UINO(ip, IN_MODIFIED);
                                mutex_exit(&lfs_lock);
                        }
                }
                KDASSERT(ip->i_number != LFS_IFILE_INUM);
                (void) lfs_writeinode(fs, sp, ip);
                mutex_enter(&lfs_lock);
                /*
                 * XXX
                 * LK_EXCLOTHER is dead -- what is intended here?
                 * if (waslocked == LK_EXCLOTHER)
                 *      LFS_SET_UINO(ip, IN_MODIFIED);
                 */
        }
        mutex_exit(&lfs_lock);
        /* We've written all the dirops there are */
        ((SEGSUM *)(sp->segsum))->ss_flags &= ~(SS_CONT);
        lfs_finalize_fs_seguse(fs);
        (void) lfs_writeseg(fs, sp);
        lfs_segunlock(fs);
}

/*
 * Flush all vnodes for which the pagedaemon has requested pageouts.
 * Skip over any files that are marked VU_DIROP (since lfs_flush_dirop()
 * has just run, this would be an error).  If we have to skip a vnode
 * for any reason, just skip it; if we have to wait for the cleaner,
 * abort.  The writer daemon will call us again later.
 */
void
lfs_flush_pchain(struct lfs *fs)
{
        struct inode *ip, *nip;
        struct vnode *vp;
        extern int lfs_dostats;
        struct segment *sp;
        int error;

        ASSERT_NO_SEGLOCK(fs);

        if (fs->lfs_ronly)
                return;

        mutex_enter(&lfs_lock);
        if (TAILQ_FIRST(&fs->lfs_pchainhd) == NULL) {
                mutex_exit(&lfs_lock);
                return;
        } else
                mutex_exit(&lfs_lock);

        /* Get dirops out of the way */
        lfs_flush_dirops(fs);

        if (lfs_dostats)
                ++lfs_stats.flush_invoked;

        /*
         * Inline lfs_segwrite/lfs_writevnodes, but just for pageouts.
         */
        lfs_imtime(fs);
        lfs_seglock(fs, 0);
        sp = fs->lfs_sp;

        /*
         * lfs_writevnodes, optimized to clear pageout requests.
         * Only write non-dirop files that are in the pageout queue.
         * We're very conservative about what we write; we want to be
         * fast and async.
         */
        mutex_enter(&lfs_lock);
    top:
        for (ip = TAILQ_FIRST(&fs->lfs_pchainhd); ip != NULL; ip = nip) {
                nip = TAILQ_NEXT(ip, i_lfs_pchain);
                vp = ITOV(ip);

                if (!(ip->i_flags & IN_PAGING))
                        goto top;

                mutex_enter(vp->v_interlock);
                if ((vp->v_iflag & VI_XLOCK) || (vp->v_uflag & VU_DIROP) != 0) {
                        mutex_exit(vp->v_interlock);
                        continue;
                }
                if (vp->v_type != VREG) {
                        mutex_exit(vp->v_interlock);
                        continue;
                }
                if (lfs_vref(vp))
                        continue;
                mutex_exit(&lfs_lock);

                if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_RETRY) != 0) {
                        lfs_vunref(vp);
                        mutex_enter(&lfs_lock);
                        continue;
                }

                error = lfs_writefile(fs, sp, vp);
                if (!VPISEMPTY(vp) && !WRITEINPROG(vp) &&
                    !(ip->i_flag & IN_ALLMOD)) {
                        mutex_enter(&lfs_lock);
                        LFS_SET_UINO(ip, IN_MODIFIED);
                        mutex_exit(&lfs_lock);
                }
                KDASSERT(ip->i_number != LFS_IFILE_INUM);
                (void) lfs_writeinode(fs, sp, ip);

                VOP_UNLOCK(vp);
                lfs_vunref(vp);

                if (error == EAGAIN) {
                        lfs_writeseg(fs, sp);
                        mutex_enter(&lfs_lock);
                        break;
                }
                mutex_enter(&lfs_lock);
        }
        mutex_exit(&lfs_lock);
        (void) lfs_writeseg(fs, sp);
        lfs_segunlock(fs);
}

/*
 * Provide a fcntl interface to sys_lfs_{segwait,bmapv,markv}.
 */
int
lfs_fcntl(void *v)
{
        struct vop_fcntl_args /* {
                struct vnode *a_vp;
                u_int a_command;
                void * a_data;
                int  a_fflag;
                kauth_cred_t a_cred;
        } */ *ap = v;
        struct timeval tv;
        struct timeval *tvp;
        BLOCK_INFO *blkiov;
        CLEANERINFO *cip;
        SEGUSE *sup;
        int blkcnt, error, oclean;
        size_t fh_size;
        struct lfs_fcntl_markv blkvp;
        struct lwp *l;
        fsid_t *fsidp;
        struct lfs *fs;
        struct buf *bp;
        fhandle_t *fhp;
        daddr_t off;

        /* Only respect LFS fcntls on fs root or Ifile */
        if (VTOI(ap->a_vp)->i_number != ROOTINO &&
            VTOI(ap->a_vp)->i_number != LFS_IFILE_INUM) {
                return ufs_fcntl(v);
        }

        /* Avoid locking a draining lock */
        if (ap->a_vp->v_mount->mnt_iflag & IMNT_UNMOUNT) {
                return ESHUTDOWN;
        }

        /* LFS control and monitoring fcntls are available only to root */
        l = curlwp;
        if (((ap->a_command & 0xff00) >> 8) == 'L' &&
            (error = kauth_authorize_generic(l->l_cred, KAUTH_GENERIC_ISSUSER,
                                             NULL)) != 0)
                return (error);

        fs = VTOI(ap->a_vp)->i_lfs;
        fsidp = &ap->a_vp->v_mount->mnt_stat.f_fsidx;

        error = 0;
        switch ((int)ap->a_command) {
            case LFCNSEGWAITALL_COMPAT_50:
            case LFCNSEGWAITALL_COMPAT:
                fsidp = NULL;
                /* FALLSTHROUGH */
            case LFCNSEGWAIT_COMPAT_50:
            case LFCNSEGWAIT_COMPAT:
                {
                        struct timeval50 *tvp50
                                = (struct timeval50 *)ap->a_data;
                        timeval50_to_timeval(tvp50, &tv);
                        tvp = &tv;
                }
                goto segwait_common;
            case LFCNSEGWAITALL:
                fsidp = NULL;
                /* FALLSTHROUGH */
            case LFCNSEGWAIT:
                tvp = (struct timeval *)ap->a_data;
segwait_common:
                mutex_enter(&lfs_lock);
                ++fs->lfs_sleepers;
                mutex_exit(&lfs_lock);

                error = lfs_segwait(fsidp, tvp);

                mutex_enter(&lfs_lock);
                if (--fs->lfs_sleepers == 0)
                        wakeup(&fs->lfs_sleepers);
                mutex_exit(&lfs_lock);
                return error;

            case LFCNBMAPV:
            case LFCNMARKV:
                blkvp = *(struct lfs_fcntl_markv *)ap->a_data;

                blkcnt = blkvp.blkcnt;
                if ((u_int) blkcnt > LFS_MARKV_MAXBLKCNT)
                        return (EINVAL);
                blkiov = lfs_malloc(fs, blkcnt * sizeof(BLOCK_INFO), LFS_NB_BLKIOV);
                if ((error = copyin(blkvp.blkiov, blkiov,
                     blkcnt * sizeof(BLOCK_INFO))) != 0) {
                        lfs_free(fs, blkiov, LFS_NB_BLKIOV);
                        return error;
                }

                mutex_enter(&lfs_lock);
                ++fs->lfs_sleepers;
                mutex_exit(&lfs_lock);
                if (ap->a_command == LFCNBMAPV)
                        error = lfs_bmapv(l->l_proc, fsidp, blkiov, blkcnt);
                else /* LFCNMARKV */
                        error = lfs_markv(l->l_proc, fsidp, blkiov, blkcnt);
                if (error == 0)
                        error = copyout(blkiov, blkvp.blkiov,
                                        blkcnt * sizeof(BLOCK_INFO));
                mutex_enter(&lfs_lock);
                if (--fs->lfs_sleepers == 0)
                        wakeup(&fs->lfs_sleepers);
                mutex_exit(&lfs_lock);
                lfs_free(fs, blkiov, LFS_NB_BLKIOV);
                return error;

            case LFCNRECLAIM:
                /*
                 * Flush dirops and write Ifile, allowing empty segments
                 * to be immediately reclaimed.
                 */
                lfs_writer_enter(fs, "pndirop");
                off = fs->lfs_offset;
                lfs_seglock(fs, SEGM_FORCE_CKP | SEGM_CKP);
                lfs_flush_dirops(fs);
                LFS_CLEANERINFO(cip, fs, bp);
                oclean = cip->clean;
                LFS_SYNC_CLEANERINFO(cip, fs, bp, 1);
                lfs_segwrite(ap->a_vp->v_mount, SEGM_FORCE_CKP);
                fs->lfs_sp->seg_flags |= SEGM_PROT;
                lfs_segunlock(fs);
                lfs_writer_leave(fs);

#ifdef DEBUG
                LFS_CLEANERINFO(cip, fs, bp);
                DLOG((DLOG_CLEAN, "lfs_fcntl: reclaim wrote %" PRId64
                      " blocks, cleaned %" PRId32 " segments (activesb %d)\n",
                      fs->lfs_offset - off, cip->clean - oclean,
                      fs->lfs_activesb));
                LFS_SYNC_CLEANERINFO(cip, fs, bp, 0);
#endif

                return 0;

            case LFCNIFILEFH_COMPAT:
                /* Return the filehandle of the Ifile */
                if ((error = kauth_authorize_system(l->l_cred,
                    KAUTH_SYSTEM_FILEHANDLE, 0, NULL, NULL, NULL)) != 0)
                        return (error);
                fhp = (struct fhandle *)ap->a_data;
                fhp->fh_fsid = *fsidp;
                fh_size = 16;   /* former VFS_MAXFIDSIZ */
                return lfs_vptofh(fs->lfs_ivnode, &(fhp->fh_fid), &fh_size);

            case LFCNIFILEFH_COMPAT2:
            case LFCNIFILEFH:
                /* Return the filehandle of the Ifile */
                fhp = (struct fhandle *)ap->a_data;
                fhp->fh_fsid = *fsidp;
                fh_size = sizeof(struct lfs_fhandle) -
                    offsetof(fhandle_t, fh_fid);
                return lfs_vptofh(fs->lfs_ivnode, &(fhp->fh_fid), &fh_size);

            case LFCNREWIND:
                /* Move lfs_offset to the lowest-numbered segment */
                return lfs_rewind(fs, *(int *)ap->a_data);

            case LFCNINVAL:
                /* Mark a segment SEGUSE_INVAL */
                LFS_SEGENTRY(sup, fs, *(int *)ap->a_data, bp);
                if (sup->su_nbytes > 0) {
                        brelse(bp, 0);
                        lfs_unset_inval_all(fs);
                        return EBUSY;
                }
                sup->su_flags |= SEGUSE_INVAL;
                VOP_BWRITE(bp->b_vp, bp);
                return 0;

            case LFCNRESIZE:
                /* Resize the filesystem */
                return lfs_resize_fs(fs, *(int *)ap->a_data);

            case LFCNWRAPSTOP:
            case LFCNWRAPSTOP_COMPAT:
                /*
                 * Hold lfs_newseg at segment 0; if requested, sleep until
                 * the filesystem wraps around.  To support external agents
                 * (dump, fsck-based regression test) that need to look at
                 * a snapshot of the filesystem, without necessarily
                 * requiring that all fs activity stops.
                 */
                if (fs->lfs_stoplwp == curlwp)
                        return EALREADY;

                mutex_enter(&lfs_lock);
                while (fs->lfs_stoplwp != NULL)
                        cv_wait(&fs->lfs_stopcv, &lfs_lock);
                fs->lfs_stoplwp = curlwp;
                if (fs->lfs_nowrap == 0)
                        log(LOG_NOTICE, "%s: disabled log wrap\n", fs->lfs_fsmnt);
                ++fs->lfs_nowrap;
                if (*(int *)ap->a_data == 1
                    || ap->a_command == LFCNWRAPSTOP_COMPAT) {
                        log(LOG_NOTICE, "LFCNSTOPWRAP waiting for log wrap\n");
                        error = mtsleep(&fs->lfs_nowrap, PCATCH | PUSER,
                                "segwrap", 0, &lfs_lock);
                        log(LOG_NOTICE, "LFCNSTOPWRAP done waiting\n");
                        if (error) {
                                lfs_wrapgo(fs, VTOI(ap->a_vp), 0);
                        }
                }
                mutex_exit(&lfs_lock);
                return 0;

            case LFCNWRAPGO:
            case LFCNWRAPGO_COMPAT:
                /*
                 * Having done its work, the agent wakes up the writer.
                 * If the argument is 1, it sleeps until a new segment
                 * is selected.
                 */
                mutex_enter(&lfs_lock);
                error = lfs_wrapgo(fs, VTOI(ap->a_vp),
                                   ap->a_command == LFCNWRAPGO_COMPAT ? 1 :
                                    *((int *)ap->a_data));
                mutex_exit(&lfs_lock);
                return error;

            case LFCNWRAPPASS:
                if ((VTOI(ap->a_vp)->i_lfs_iflags & LFSI_WRAPWAIT))
                        return EALREADY;
                mutex_enter(&lfs_lock);
                if (fs->lfs_stoplwp != curlwp) {
                        mutex_exit(&lfs_lock);
                        return EALREADY;
                }
                if (fs->lfs_nowrap == 0) {
                        mutex_exit(&lfs_lock);
                        return EBUSY;
                }
                fs->lfs_wrappass = 1;
                wakeup(&fs->lfs_wrappass);
                /* Wait for the log to wrap, if asked */
                if (*(int *)ap->a_data) {
                        mutex_enter(ap->a_vp->v_interlock);
                        lfs_vref(ap->a_vp);
                        VTOI(ap->a_vp)->i_lfs_iflags |= LFSI_WRAPWAIT;
                        log(LOG_NOTICE, "LFCNPASS waiting for log wrap\n");
                        error = mtsleep(&fs->lfs_nowrap, PCATCH | PUSER,
                                "segwrap", 0, &lfs_lock);
                        log(LOG_NOTICE, "LFCNPASS done waiting\n");
                        VTOI(ap->a_vp)->i_lfs_iflags &= ~LFSI_WRAPWAIT;
                        lfs_vunref(ap->a_vp);
                }
                mutex_exit(&lfs_lock);
                return error;

            case LFCNWRAPSTATUS:
                mutex_enter(&lfs_lock);
                *(int *)ap->a_data = fs->lfs_wrapstatus;
                mutex_exit(&lfs_lock);
                return 0;

            default:
                return ufs_fcntl(v);
        }
        return 0;
}

int
lfs_getpages(void *v)
{
        struct vop_getpages_args /* {
                struct vnode *a_vp;
                voff_t a_offset;
                struct vm_page **a_m;
                int *a_count;
                int a_centeridx;
                vm_prot_t a_access_type;
                int a_advice;
                int a_flags;
        } */ *ap = v;

        if (VTOI(ap->a_vp)->i_number == LFS_IFILE_INUM &&
            (ap->a_access_type & VM_PROT_WRITE) != 0) {
                return EPERM;
        }
        if ((ap->a_access_type & VM_PROT_WRITE) != 0) {
                mutex_enter(&lfs_lock);
                LFS_SET_UINO(VTOI(ap->a_vp), IN_MODIFIED);
                mutex_exit(&lfs_lock);
        }

        /*
         * we're relying on the fact that genfs_getpages() always read in
         * entire filesystem blocks.
         */
        return genfs_getpages(v);
}

/*
 * Wait for a page to become unbusy, possibly printing diagnostic messages
 * as well.
 *
 * Called with vp->v_interlock held; return with it held.
 */
static void
wait_for_page(struct vnode *vp, struct vm_page *pg, const char *label)
{
        if ((pg->flags & PG_BUSY) == 0)
                return;         /* Nothing to wait for! */

#if defined(DEBUG) && defined(UVM_PAGE_TRKOWN)
        static struct vm_page *lastpg;

        if (label != NULL && pg != lastpg) {
                if (pg->owner_tag) {
                        printf("lfs_putpages[%d.%d]: %s: page %p owner %d.%d [%s]\n",
                               curproc->p_pid, curlwp->l_lid, label,
                               pg, pg->owner, pg->lowner, pg->owner_tag);
                } else {
                        printf("lfs_putpages[%d.%d]: %s: page %p unowned?!\n",
                               curproc->p_pid, curlwp->l_lid, label, pg);
                }
        }
        lastpg = pg;
#endif

        pg->flags |= PG_WANTED;
        UVM_UNLOCK_AND_WAIT(pg, vp->v_interlock, 0, "lfsput", 0);
        mutex_enter(vp->v_interlock);
}

/*
 * This routine is called by lfs_putpages() when it can't complete the
 * write because a page is busy.  This means that either (1) someone,
 * possibly the pagedaemon, is looking at this page, and will give it up
 * presently; or (2) we ourselves are holding the page busy in the
 * process of being written (either gathered or actually on its way to
 * disk).  We don't need to give up the segment lock, but we might need
 * to call lfs_writeseg() to expedite the page's journey to disk.
 *
 * Called with vp->v_interlock held; return with it held.
 */
/* #define BUSYWAIT */
static void
write_and_wait(struct lfs *fs, struct vnode *vp, struct vm_page *pg,
               int seglocked, const char *label)
{
#ifndef BUSYWAIT
        struct inode *ip = VTOI(vp);
        struct segment *sp = fs->lfs_sp;
        int count = 0;

        if (pg == NULL)
                return;

        while (pg->flags & PG_BUSY &&
            pg->uobject == &vp->v_uobj) {
                mutex_exit(vp->v_interlock);
                if (sp->cbpp - sp->bpp > 1) {
                        /* Write gathered pages */
                        lfs_updatemeta(sp);
                        lfs_release_finfo(fs);
                        (void) lfs_writeseg(fs, sp);

                        /*
                         * Reinitialize FIP
                         */
                        KASSERT(sp->vp == vp);
                        lfs_acquire_finfo(fs, ip->i_number,
                                          ip->i_gen);
                }
                ++count;
                mutex_enter(vp->v_interlock);
                wait_for_page(vp, pg, label);
        }
        if (label != NULL && count > 1)
                printf("lfs_putpages[%d]: %s: %sn = %d\n", curproc->p_pid,
                       label, (count > 0 ? "looping, " : ""), count);
#else
        preempt(1);
#endif
}

/*
 * Make sure that for all pages in every block in the given range,
 * either all are dirty or all are clean.  If any of the pages
 * we've seen so far are dirty, put the vnode on the paging chain,
 * and mark it IN_PAGING.
 *
 * If checkfirst != 0, don't check all the pages but return at the
 * first dirty page.
 */
static int
check_dirty(struct lfs *fs, struct vnode *vp,
            off_t startoffset, off_t endoffset, off_t blkeof,
            int flags, int checkfirst, struct vm_page **pgp)
{
        int by_list;
        struct vm_page *curpg = NULL; /* XXX: gcc */
        struct vm_page *pgs[MAXBSIZE / PAGE_SIZE], *pg;
        off_t soff = 0; /* XXX: gcc */
        voff_t off;
        int i;
        int nonexistent;
        int any_dirty;  /* number of dirty pages */
        int dirty;      /* number of dirty pages in a block */
        int tdirty;
        int pages_per_block = fs->lfs_bsize >> PAGE_SHIFT;
        int pagedaemon = (curlwp == uvm.pagedaemon_lwp);

        ASSERT_MAYBE_SEGLOCK(fs);
  top:
        by_list = (vp->v_uobj.uo_npages <=
                   ((endoffset - startoffset) >> PAGE_SHIFT) *
                   UVM_PAGE_TREE_PENALTY);
        any_dirty = 0;

        if (by_list) {
                curpg = TAILQ_FIRST(&vp->v_uobj.memq);
        } else {
                soff = startoffset;
        }
        while (by_list || soff < MIN(blkeof, endoffset)) {
                if (by_list) {
                        /*
                         * Find the first page in a block.  Skip
                         * blocks outside our area of interest or beyond
                         * the end of file.
                         */
                        KASSERT(curpg == NULL
                            || (curpg->flags & PG_MARKER) == 0);
                        if (pages_per_block > 1) {
                                while (curpg &&
                                    ((curpg->offset & fs->lfs_bmask) ||
                                    curpg->offset >= vp->v_size ||
                                    curpg->offset >= endoffset)) {
                                        curpg = TAILQ_NEXT(curpg, listq.queue);
                                        KASSERT(curpg == NULL ||
                                            (curpg->flags & PG_MARKER) == 0);
                                }
                        }
                        if (curpg == NULL)
                                break;
                        soff = curpg->offset;
                }

                /*
                 * Mark all pages in extended range busy; find out if any
                 * of them are dirty.
                 */
                nonexistent = dirty = 0;
                for (i = 0; i == 0 || i < pages_per_block; i++) {
                        if (by_list && pages_per_block <= 1) {
                                pgs[i] = pg = curpg;
                        } else {
                                off = soff + (i << PAGE_SHIFT);
                                pgs[i] = pg = uvm_pagelookup(&vp->v_uobj, off);
                                if (pg == NULL) {
                                        ++nonexistent;
                                        continue;
                                }
                        }
                        KASSERT(pg != NULL);

                        /*
                         * If we're holding the segment lock, we can deadlock
                         * against a process that has our page and is waiting
                         * for the cleaner, while the cleaner waits for the
                         * segment lock.  Just bail in that case.
                         */
                        if ((pg->flags & PG_BUSY) &&
                            (pagedaemon || LFS_SEGLOCK_HELD(fs))) {
                                if (i > 0)
                                        uvm_page_unbusy(pgs, i);
                                DLOG((DLOG_PAGE, "lfs_putpages: avoiding 3-way or pagedaemon deadlock\n"));
                                if (pgp)
                                        *pgp = pg;
                                return -1;
                        }

                        while (pg->flags & PG_BUSY) {
                                wait_for_page(vp, pg, NULL);
                                if (i > 0)
                                        uvm_page_unbusy(pgs, i);
                                goto top;
                        }
                        pg->flags |= PG_BUSY;
                        UVM_PAGE_OWN(pg, "lfs_putpages");

                        pmap_page_protect(pg, VM_PROT_NONE);
                        tdirty = (pmap_clear_modify(pg) ||
                                  (pg->flags & PG_CLEAN) == 0);
                        dirty += tdirty;
                }
                if (pages_per_block > 0 && nonexistent >= pages_per_block) {
                        if (by_list) {
                                curpg = TAILQ_NEXT(curpg, listq.queue);
                        } else {
                                soff += fs->lfs_bsize;
                        }
                        continue;
                }

                any_dirty += dirty;
                KASSERT(nonexistent == 0);

                /*
                 * If any are dirty make all dirty; unbusy them,
                 * but if we were asked to clean, wire them so that
                 * the pagedaemon doesn't bother us about them while
                 * they're on their way to disk.
                 */
                for (i = 0; i == 0 || i < pages_per_block; i++) {
                        pg = pgs[i];
                        KASSERT(!((pg->flags & PG_CLEAN) && (pg->flags & PG_DELWRI)));
                        if (dirty) {
                                pg->flags &= ~PG_CLEAN;
                                if (flags & PGO_FREE) {
                                        /*
                                         * Wire the page so that
                                         * pdaemon doesn't see it again.
                                         */
                                        mutex_enter(&uvm_pageqlock);
                                        uvm_pagewire(pg);
                                        mutex_exit(&uvm_pageqlock);

                                        /* Suspended write flag */
                                        pg->flags |= PG_DELWRI;
                                }
                        }
                        if (pg->flags & PG_WANTED)
                                wakeup(pg);
                        pg->flags &= ~(PG_WANTED|PG_BUSY);
                        UVM_PAGE_OWN(pg, NULL);
                }

                if (checkfirst && any_dirty)
                        break;

                if (by_list) {
                        curpg = TAILQ_NEXT(curpg, listq.queue);
                } else {
                        soff += MAX(PAGE_SIZE, fs->lfs_bsize);
                }
        }

        return any_dirty;
}

/*
 * lfs_putpages functions like genfs_putpages except that
 *
 * (1) It needs to bounds-check the incoming requests to ensure that
 *     they are block-aligned; if they are not, expand the range and
 *     do the right thing in case, e.g., the requested range is clean
 *     but the expanded range is dirty.
 *
 * (2) It needs to explicitly send blocks to be written when it is done.
 *     If VOP_PUTPAGES is called without the seglock held, we simply take
 *     the seglock and let lfs_segunlock wait for us.
 *     XXX There might be a bad situation if we have to flush a vnode while
 *     XXX lfs_markv is in operation.  As of this writing we panic in this
 *     XXX case.
 *
 * Assumptions:
 *
 * (1) The caller does not hold any pages in this vnode busy.  If it does,
 *     there is a danger that when we expand the page range and busy the
 *     pages we will deadlock.
 *
 * (2) We are called with vp->v_interlock held; we must return with it
 *     released.
 *
 * (3) We don't absolutely have to free pages right away, provided that
 *     the request does not have PGO_SYNCIO.  When the pagedaemon gives
 *     us a request with PGO_FREE, we take the pages out of the paging
 *     queue and wake up the writer, which will handle freeing them for us.
 *
 *     We ensure that for any filesystem block, all pages for that
 *     block are either resident or not, even if those pages are higher
 *     than EOF; that means that we will be getting requests to free
 *     "unused" pages above EOF all the time, and should ignore them.
 *
 * (4) If we are called with PGO_LOCKED, the finfo array we are to write
 *     into has been set up for us by lfs_writefile.  If not, we will
 *     have to handle allocating and/or freeing an finfo entry.
 *
 * XXX note that we're (ab)using PGO_LOCKED as "seglock held".
 */

/* How many times to loop before we should start to worry */
#define TOOMANY 4

int
lfs_putpages(void *v)
{
        int error;
        struct vop_putpages_args /* {
                struct vnode *a_vp;
                voff_t a_offlo;
                voff_t a_offhi;
                int a_flags;
        } */ *ap = v;
        struct vnode *vp;
        struct inode *ip;
        struct lfs *fs;
        struct segment *sp;
        off_t origoffset, startoffset, endoffset, origendoffset, blkeof;
        off_t off, max_endoffset;
        bool seglocked, sync, pagedaemon;
        struct vm_page *pg, *busypg;
        UVMHIST_FUNC("lfs_putpages"); UVMHIST_CALLED(ubchist);
#ifdef DEBUG
        int debug_n_again, debug_n_dirtyclean;
#endif

        vp = ap->a_vp;
        ip = VTOI(vp);
        fs = ip->i_lfs;
        sync = (ap->a_flags & PGO_SYNCIO) != 0;
        pagedaemon = (curlwp == uvm.pagedaemon_lwp);

        /* Putpages does nothing for metadata. */
        if (vp == fs->lfs_ivnode || vp->v_type != VREG) {
                mutex_exit(vp->v_interlock);
                return 0;
        }

        /*
         * If there are no pages, don't do anything.
         */
        if (vp->v_uobj.uo_npages == 0) {
                if (TAILQ_EMPTY(&vp->v_uobj.memq) &&
                    (vp->v_iflag & VI_ONWORKLST) &&
                    LIST_FIRST(&vp->v_dirtyblkhd) == NULL) {
                        vp->v_iflag &= ~VI_WRMAPDIRTY;
                        vn_syncer_remove_from_worklist(vp);
                }
                mutex_exit(vp->v_interlock);
                
                /* Remove us from paging queue, if we were on it */
                mutex_enter(&lfs_lock);
                if (ip->i_flags & IN_PAGING) {
                        ip->i_flags &= ~IN_PAGING;
                        TAILQ_REMOVE(&fs->lfs_pchainhd, ip, i_lfs_pchain);
                }
                mutex_exit(&lfs_lock);
                return 0;
        }

        blkeof = blkroundup(fs, ip->i_size);

        /*
         * Ignore requests to free pages past EOF but in the same block
         * as EOF, unless the request is synchronous.  (If the request is
         * sync, it comes from lfs_truncate.)
         * XXXUBC Make these pages look "active" so the pagedaemon won't
         * XXXUBC bother us with them again.
         */
        if (!sync && ap->a_offlo >= ip->i_size && ap->a_offlo < blkeof) {
                origoffset = ap->a_offlo;
                for (off = origoffset; off < blkeof; off += fs->lfs_bsize) {
                        pg = uvm_pagelookup(&vp->v_uobj, off);
                        KASSERT(pg != NULL);
                        while (pg->flags & PG_BUSY) {
                                pg->flags |= PG_WANTED;
                                UVM_UNLOCK_AND_WAIT(pg, vp->v_interlock, 0,
                                                    "lfsput2", 0);
                                mutex_enter(vp->v_interlock);
                        }
                        mutex_enter(&uvm_pageqlock);
                        uvm_pageactivate(pg);
                        mutex_exit(&uvm_pageqlock);
                }
                ap->a_offlo = blkeof;
                if (ap->a_offhi > 0 && ap->a_offhi <= ap->a_offlo) {
                        mutex_exit(vp->v_interlock);
                        return 0;
                }
        }

        /*
         * Extend page range to start and end at block boundaries.
         * (For the purposes of VOP_PUTPAGES, fragments don't exist.)
         */
        origoffset = ap->a_offlo;
        origendoffset = ap->a_offhi;
        startoffset = origoffset & ~(fs->lfs_bmask);
        max_endoffset = (trunc_page(LLONG_MAX) >> fs->lfs_bshift)
                                               << fs->lfs_bshift;

        if (origendoffset == 0 || ap->a_flags & PGO_ALLPAGES) {
                endoffset = max_endoffset;
                origendoffset = endoffset;
        } else {
                origendoffset = round_page(ap->a_offhi);
                endoffset = round_page(blkroundup(fs, origendoffset));
        }

        KASSERT(startoffset > 0 || endoffset >= startoffset);
        if (startoffset == endoffset) {
                /* Nothing to do, why were we called? */
                mutex_exit(vp->v_interlock);
                DLOG((DLOG_PAGE, "lfs_putpages: startoffset = endoffset = %"
                      PRId64 "\n", startoffset));
                return 0;
        }

        ap->a_offlo = startoffset;
        ap->a_offhi = endoffset;

        /*
         * If not cleaning, just send the pages through genfs_putpages
         * to be returned to the pool.
         */
        if (!(ap->a_flags & PGO_CLEANIT))
                return genfs_putpages(v);

        /* Set PGO_BUSYFAIL to avoid deadlocks */
        ap->a_flags |= PGO_BUSYFAIL;

        /*
         * Likewise, if we are asked to clean but the pages are not
         * dirty, we can just free them using genfs_putpages.
         */
#ifdef DEBUG
        debug_n_dirtyclean = 0;
#endif
        do {
                int r;

                /* Count the number of dirty pages */
                r = check_dirty(fs, vp, startoffset, endoffset, blkeof,
                                ap->a_flags, 1, NULL);
                if (r < 0) {
                        /* Pages are busy with another process */
                        mutex_exit(vp->v_interlock);
                        return EDEADLK;
                }
                if (r > 0) /* Some pages are dirty */
                        break;

                /*
                 * Sometimes pages are dirtied between the time that
                 * we check and the time we try to clean them.
                 * Instruct lfs_gop_write to return EDEADLK in this case
                 * so we can write them properly.
                 */
                ip->i_lfs_iflags |= LFSI_NO_GOP_WRITE;
                r = genfs_do_putpages(vp, startoffset, endoffset,
                                       ap->a_flags & ~PGO_SYNCIO, &busypg);
                ip->i_lfs_iflags &= ~LFSI_NO_GOP_WRITE;
                if (r != EDEADLK)
                        return r;

                /* One of the pages was busy.  Start over. */
                mutex_enter(vp->v_interlock);
                wait_for_page(vp, busypg, "dirtyclean");
#ifdef DEBUG
                ++debug_n_dirtyclean;
#endif
        } while(1);

#ifdef DEBUG
        if (debug_n_dirtyclean > TOOMANY)
                printf("lfs_putpages: dirtyclean: looping, n = %d\n",
                       debug_n_dirtyclean);
#endif

        /*
         * Dirty and asked to clean.
         *
         * Pagedaemon can't actually write LFS pages; wake up
         * the writer to take care of that.  The writer will
         * notice the pager inode queue and act on that.
         *
         * XXX We must drop the vp->interlock before taking the lfs_lock or we
         * get a nasty deadlock with lfs_flush_pchain().
         */
        if (pagedaemon) {
                mutex_exit(vp->v_interlock);
                mutex_enter(&lfs_lock);
                if (!(ip->i_flags & IN_PAGING)) {
                        ip->i_flags |= IN_PAGING;
                        TAILQ_INSERT_TAIL(&fs->lfs_pchainhd, ip, i_lfs_pchain);
                } 
                wakeup(&lfs_writer_daemon);
                mutex_exit(&lfs_lock);
                preempt();
                return EWOULDBLOCK;
        }

        /*
         * If this is a file created in a recent dirop, we can't flush its
         * inode until the dirop is complete.  Drain dirops, then flush the
         * filesystem (taking care of any other pending dirops while we're
         * at it).
         */
        if ((ap->a_flags & (PGO_CLEANIT|PGO_LOCKED)) == PGO_CLEANIT &&
            (vp->v_uflag & VU_DIROP)) {
                int locked;

                DLOG((DLOG_PAGE, "lfs_putpages: flushing VU_DIROP\n"));
                /* XXX VOP_ISLOCKED() may not be used for lock decisions. */
                locked = (VOP_ISLOCKED(vp) == LK_EXCLUSIVE);
                mutex_exit(vp->v_interlock);
                lfs_writer_enter(fs, "ppdirop");
                if (locked)
                        VOP_UNLOCK(vp); /* XXX why? */

                mutex_enter(&lfs_lock);
                lfs_flush_fs(fs, sync ? SEGM_SYNC : 0);
                mutex_exit(&lfs_lock);

                if (locked)
                        VOP_LOCK(vp, LK_EXCLUSIVE);
                mutex_enter(vp->v_interlock);
                lfs_writer_leave(fs);

                /* XXX the flush should have taken care of this one too! */
        }

        /*
         * This is it.  We are going to write some pages.  From here on
         * down it's all just mechanics.
         *
         * Don't let genfs_putpages wait; lfs_segunlock will wait for us.
         */
        ap->a_flags &= ~PGO_SYNCIO;

        /*
         * If we've already got the seglock, flush the node and return.
         * The FIP has already been set up for us by lfs_writefile,
         * and FIP cleanup and lfs_updatemeta will also be done there,
         * unless genfs_putpages returns EDEADLK; then we must flush
         * what we have, and correct FIP and segment header accounting.
         */
  get_seglock:
        /*
         * If we are not called with the segment locked, lock it.
         * Account for a new FIP in the segment header, and set sp->vp.
         * (This should duplicate the setup at the top of lfs_writefile().)
         */
        seglocked = (ap->a_flags & PGO_LOCKED) != 0;
        if (!seglocked) {
                mutex_exit(vp->v_interlock);
                error = lfs_seglock(fs, SEGM_PROT | (sync ? SEGM_SYNC : 0));
                if (error != 0)
                        return error;
                mutex_enter(vp->v_interlock);
                lfs_acquire_finfo(fs, ip->i_number, ip->i_gen);
        }
        sp = fs->lfs_sp;
        KASSERT(sp->vp == NULL);
        sp->vp = vp;

        /*
         * Ensure that the partial segment is marked SS_DIROP if this
         * vnode is a DIROP.
         */
        if (!seglocked && vp->v_uflag & VU_DIROP)
                ((SEGSUM *)(sp->segsum))->ss_flags |= (SS_DIROP|SS_CONT);

        /*
         * Loop over genfs_putpages until all pages are gathered.
         * genfs_putpages() drops the interlock, so reacquire it if necessary.
         * Whenever we lose the interlock we have to rerun check_dirty, as
         * well, since more pages might have been dirtied in our absence.
         */
#ifdef DEBUG
        debug_n_again = 0;
#endif
        do {
                busypg = NULL;
                if (check_dirty(fs, vp, startoffset, endoffset, blkeof,
                                ap->a_flags, 0, &busypg) < 0) {
                        mutex_exit(vp->v_interlock);

                        mutex_enter(vp->v_interlock);
                        write_and_wait(fs, vp, busypg, seglocked, NULL);
                        if (!seglocked) {
                                mutex_exit(vp->v_interlock);
                                lfs_release_finfo(fs);
                                lfs_segunlock(fs);
                                mutex_enter(vp->v_interlock);
                        }
                        sp->vp = NULL;
                        goto get_seglock;
                }
        
                busypg = NULL;
                error = genfs_do_putpages(vp, startoffset, endoffset,
                                           ap->a_flags, &busypg);
        
                if (error == EDEADLK || error == EAGAIN) {
                        DLOG((DLOG_PAGE, "lfs_putpages: genfs_putpages returned"
                              " %d ino %d off %x (seg %d)\n", error,
                              ip->i_number, fs->lfs_offset,
                              dtosn(fs, fs->lfs_offset)));

                        mutex_enter(vp->v_interlock);
                        write_and_wait(fs, vp, busypg, seglocked, "again");
                }
#ifdef DEBUG
                ++debug_n_again;
#endif
        } while (error == EDEADLK);
#ifdef DEBUG
        if (debug_n_again > TOOMANY)
                printf("lfs_putpages: again: looping, n = %d\n", debug_n_again);
#endif

        KASSERT(sp != NULL && sp->vp == vp);
        if (!seglocked) {
                sp->vp = NULL;

                /* Write indirect blocks as well */
                lfs_gather(fs, fs->lfs_sp, vp, lfs_match_indir);
                lfs_gather(fs, fs->lfs_sp, vp, lfs_match_dindir);
                lfs_gather(fs, fs->lfs_sp, vp, lfs_match_tindir);

                KASSERT(sp->vp == NULL);
                sp->vp = vp;
        }

        /*
         * Blocks are now gathered into a segment waiting to be written.
         * All that's left to do is update metadata, and write them.
         */
        lfs_updatemeta(sp);
        KASSERT(sp->vp == vp);
        sp->vp = NULL;

        /*
         * If we were called from lfs_writefile, we don't need to clean up
         * the FIP or unlock the segment lock.  We're done.
         */
        if (seglocked)
                return error;

        /* Clean up FIP and send it to disk. */
        lfs_release_finfo(fs);
        lfs_writeseg(fs, fs->lfs_sp);

        /*
         * Remove us from paging queue if we wrote all our pages.
         */
        if (origendoffset == 0 || ap->a_flags & PGO_ALLPAGES) {
                mutex_enter(&lfs_lock);
                if (ip->i_flags & IN_PAGING) {
                        ip->i_flags &= ~IN_PAGING;
                        TAILQ_REMOVE(&fs->lfs_pchainhd, ip, i_lfs_pchain);
                }
                mutex_exit(&lfs_lock);
        }

        /*
         * XXX - with the malloc/copy writeseg, the pages are freed by now
         * even if we don't wait (e.g. if we hold a nested lock).  This
         * will not be true if we stop using malloc/copy.
         */
        KASSERT(fs->lfs_sp->seg_flags & SEGM_PROT);
        lfs_segunlock(fs);

        /*
         * Wait for v_numoutput to drop to zero.  The seglock should
         * take care of this, but there is a slight possibility that
         * aiodoned might not have got around to our buffers yet.
         */
        if (sync) {
                mutex_enter(vp->v_interlock);
                while (vp->v_numoutput > 0) {
                        DLOG((DLOG_PAGE, "lfs_putpages: ino %d sleeping on"
                              " num %d\n", ip->i_number, vp->v_numoutput));
                        cv_wait(&vp->v_cv, vp->v_interlock);
                }
                mutex_exit(vp->v_interlock);
        }
        return error;
}

/*
 * Return the last logical file offset that should be written for this file
 * if we're doing a write that ends at "size".  If writing, we need to know
 * about sizes on disk, i.e. fragments if there are any; if reading, we need
 * to know about entire blocks.
 */
void
lfs_gop_size(struct vnode *vp, off_t size, off_t *eobp, int flags)
{
        struct inode *ip = VTOI(vp);
        struct lfs *fs = ip->i_lfs;
        daddr_t olbn, nlbn;

        olbn = lblkno(fs, ip->i_size);
        nlbn = lblkno(fs, size);
        if (!(flags & GOP_SIZE_MEM) && nlbn < NDADDR && olbn <= nlbn) {
                *eobp = fragroundup(fs, size);
        } else {
                *eobp = blkroundup(fs, size);
        }
}

#ifdef DEBUG
void lfs_dump_vop(void *);

void
lfs_dump_vop(void *v)
{
        struct vop_putpages_args /* {
                struct vnode *a_vp;
                voff_t a_offlo;
                voff_t a_offhi;
                int a_flags;
        } */ *ap = v;

#ifdef DDB
        vfs_vnode_print(ap->a_vp, 0, printf);
#endif
        lfs_dump_dinode(VTOI(ap->a_vp)->i_din.ffs1_din);
}
#endif

int
lfs_mmap(void *v)
{
        struct vop_mmap_args /* {
                const struct vnodeop_desc *a_desc;
                struct vnode *a_vp;
                vm_prot_t a_prot;
                kauth_cred_t a_cred;
        } */ *ap = v;

        if (VTOI(ap->a_vp)->i_number == LFS_IFILE_INUM)
                return EOPNOTSUPP;
        return ufs_mmap(v);
}