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[netbsd-mini2440.git] / sys / ufs / lfs / lfs_segment.c

/*      $NetBSD: lfs_segment.c,v 1.213 2008/06/02 16:25:34 ad 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) 1991, 1993
 *      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_segment.c       8.10 (Berkeley) 6/10/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: lfs_segment.c,v 1.213 2008/06/02 16:25:34 ad Exp $");

#ifdef DEBUG
# define vndebug(vp, str) do {                                          \
        if (VTOI(vp)->i_flag & IN_CLEANING)                             \
                DLOG((DLOG_WVNODE, "not writing ino %d because %s (op %d)\n", \
                     VTOI(vp)->i_number, (str), op));                   \
} while(0)
#else
# define vndebug(vp, str)
#endif
#define ivndebug(vp, str) \
        DLOG((DLOG_WVNODE, "ino %d: %s\n", VTOI(vp)->i_number, (str)))

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

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

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

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

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

#include <uvm/uvm.h>
#include <uvm/uvm_extern.h>

MALLOC_JUSTDEFINE(M_SEGMENT, "LFS segment", "Segment for LFS");

extern int count_lock_queue(void);
extern kmutex_t vnode_free_list_lock;           /* XXX */

static void lfs_generic_callback(struct buf *, void (*)(struct buf *));
static void lfs_free_aiodone(struct buf *);
static void lfs_super_aiodone(struct buf *);
static void lfs_cluster_aiodone(struct buf *);
static void lfs_cluster_callback(struct buf *);

/*
 * Determine if it's OK to start a partial in this segment, or if we need
 * to go on to a new segment.
 */
#define LFS_PARTIAL_FITS(fs) \
        ((fs)->lfs_fsbpseg - ((fs)->lfs_offset - (fs)->lfs_curseg) > \
        fragstofsb((fs), (fs)->lfs_frag))

/*
 * Figure out whether we should do a checkpoint write or go ahead with
 * an ordinary write.
 */
#define LFS_SHOULD_CHECKPOINT(fs, flags) \
        ((flags & SEGM_CLEAN) == 0 &&                                   \
          ((fs->lfs_nactive > LFS_MAX_ACTIVE ||                         \
            (flags & SEGM_CKP) ||                                       \
            fs->lfs_nclean < LFS_MAX_ACTIVE)))

int      lfs_match_fake(struct lfs *, struct buf *);
void     lfs_newseg(struct lfs *);
/* XXX ondisk32 */
void     lfs_shellsort(struct buf **, int32_t *, int, int);
void     lfs_supercallback(struct buf *);
void     lfs_updatemeta(struct segment *);
void     lfs_writesuper(struct lfs *, daddr_t);
int      lfs_writevnodes(struct lfs *fs, struct mount *mp,
            struct segment *sp, int dirops);

int     lfs_allclean_wakeup;            /* Cleaner wakeup address. */
int     lfs_writeindir = 1;             /* whether to flush indir on non-ckp */
int     lfs_clean_vnhead = 0;           /* Allow freeing to head of vn list */
int     lfs_dirvcount = 0;              /* # active dirops */

/* Statistics Counters */
int lfs_dostats = 1;
struct lfs_stats lfs_stats;

/* op values to lfs_writevnodes */
#define VN_REG          0
#define VN_DIROP        1
#define VN_EMPTY        2
#define VN_CLEAN        3

/*
 * XXX KS - Set modification time on the Ifile, so the cleaner can
 * read the fs mod time off of it.  We don't set IN_UPDATE here,
 * since we don't really need this to be flushed to disk (and in any
 * case that wouldn't happen to the Ifile until we checkpoint).
 */
void
lfs_imtime(struct lfs *fs)
{
        struct timespec ts;
        struct inode *ip;

        ASSERT_MAYBE_SEGLOCK(fs);
        vfs_timestamp(&ts);
        ip = VTOI(fs->lfs_ivnode);
        ip->i_ffs1_mtime = ts.tv_sec;
        ip->i_ffs1_mtimensec = ts.tv_nsec;
}

/*
 * Ifile and meta data blocks are not marked busy, so segment writes MUST be
 * single threaded.  Currently, there are two paths into lfs_segwrite, sync()
 * and getnewbuf().  They both mark the file system busy.  Lfs_vflush()
 * explicitly marks the file system busy.  So lfs_segwrite is safe.  I think.
 */

#define IS_FLUSHING(fs,vp)  ((fs)->lfs_flushvp == (vp))

int
lfs_vflush(struct vnode *vp)
{
        struct inode *ip;
        struct lfs *fs;
        struct segment *sp;
        struct buf *bp, *nbp, *tbp, *tnbp;
        int error;
        int flushed;
        int relock;
        int loopcount;

        ip = VTOI(vp);
        fs = VFSTOUFS(vp->v_mount)->um_lfs;
        relock = 0;

    top:
        ASSERT_NO_SEGLOCK(fs);
        if (ip->i_flag & IN_CLEANING) {
                ivndebug(vp,"vflush/in_cleaning");
                mutex_enter(&lfs_lock);
                LFS_CLR_UINO(ip, IN_CLEANING);
                LFS_SET_UINO(ip, IN_MODIFIED);
                mutex_exit(&lfs_lock);

                /*
                 * Toss any cleaning buffers that have real counterparts
                 * to avoid losing new data.
                 */
                mutex_enter(&vp->v_interlock);
                for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                        nbp = LIST_NEXT(bp, b_vnbufs);
                        if (!LFS_IS_MALLOC_BUF(bp))
                                continue;
                        /*
                         * Look for pages matching the range covered
                         * by cleaning blocks.  It's okay if more dirty
                         * pages appear, so long as none disappear out
                         * from under us.
                         */
                        if (bp->b_lblkno > 0 && vp->v_type == VREG &&
                            vp != fs->lfs_ivnode) {
                                struct vm_page *pg;
                                voff_t off;

                                for (off = lblktosize(fs, bp->b_lblkno);
                                     off < lblktosize(fs, bp->b_lblkno + 1);
                                     off += PAGE_SIZE) {
                                        pg = uvm_pagelookup(&vp->v_uobj, off);
                                        if (pg == NULL)
                                                continue;
                                        if ((pg->flags & PG_CLEAN) == 0 ||
                                            pmap_is_modified(pg)) {
                                                fs->lfs_avail += btofsb(fs,
                                                        bp->b_bcount);
                                                wakeup(&fs->lfs_avail);
                                                mutex_exit(&vp->v_interlock);
                                                lfs_freebuf(fs, bp);
                                                mutex_enter(&vp->v_interlock);
                                                bp = NULL;
                                                break;
                                        }
                                }
                        }
                        for (tbp = LIST_FIRST(&vp->v_dirtyblkhd); tbp;
                            tbp = tnbp)
                        {
                                tnbp = LIST_NEXT(tbp, b_vnbufs);
                                if (tbp->b_vp == bp->b_vp
                                   && tbp->b_lblkno == bp->b_lblkno
                                   && tbp != bp)
                                {
                                        fs->lfs_avail += btofsb(fs,
                                                bp->b_bcount);
                                        wakeup(&fs->lfs_avail);
                                        mutex_exit(&vp->v_interlock);
                                        lfs_freebuf(fs, bp);
                                        mutex_enter(&vp->v_interlock);
                                        bp = NULL;
                                        break;
                                }
                        }
                }
        } else {
                mutex_enter(&vp->v_interlock);
        }

        /* If the node is being written, wait until that is done */
        while (WRITEINPROG(vp)) {
                ivndebug(vp,"vflush/writeinprog");
                cv_wait(&vp->v_cv, &vp->v_interlock);
        }
        mutex_exit(&vp->v_interlock);

        /* Protect against VI_XLOCK deadlock in vinvalbuf() */
        lfs_seglock(fs, SEGM_SYNC);

        /* If we're supposed to flush a freed inode, just toss it */
        if (ip->i_lfs_iflags & LFSI_DELETED) {
                DLOG((DLOG_VNODE, "lfs_vflush: ino %d freed, not flushing\n",
                      ip->i_number));
                /* Drain v_numoutput */
                mutex_enter(&vp->v_interlock);
                while (vp->v_numoutput > 0) {
                        cv_wait(&vp->v_cv, &vp->v_interlock);
                }
                KASSERT(vp->v_numoutput == 0);
                mutex_exit(&vp->v_interlock);
        
                mutex_enter(&bufcache_lock);
                for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                        nbp = LIST_NEXT(bp, b_vnbufs);

                        KASSERT((bp->b_flags & B_GATHERED) == 0);
                        if (bp->b_oflags & BO_DELWRI) { /* XXX always true? */
                                fs->lfs_avail += btofsb(fs, bp->b_bcount);
                                wakeup(&fs->lfs_avail);
                        }
                        /* Copied from lfs_writeseg */
                        if (bp->b_iodone != NULL) {
                                mutex_exit(&bufcache_lock);
                                biodone(bp);
                                mutex_enter(&bufcache_lock);
                        } else {
                                bremfree(bp);
                                LFS_UNLOCK_BUF(bp);
                                mutex_enter(&vp->v_interlock);
                                bp->b_flags &= ~(B_READ | B_GATHERED);
                                bp->b_oflags = (bp->b_oflags & ~BO_DELWRI) | BO_DONE;
                                bp->b_error = 0;
                                reassignbuf(bp, vp);
                                mutex_exit(&vp->v_interlock);
                                brelse(bp, 0);
                        }
                }
                mutex_exit(&bufcache_lock);
                LFS_CLR_UINO(ip, IN_CLEANING);
                LFS_CLR_UINO(ip, IN_MODIFIED | IN_ACCESSED);
                ip->i_flag &= ~IN_ALLMOD;
                DLOG((DLOG_VNODE, "lfs_vflush: done not flushing ino %d\n",
                      ip->i_number));
                lfs_segunlock(fs);

                KASSERT(LIST_FIRST(&vp->v_dirtyblkhd) == NULL);

                return 0;
        }

        fs->lfs_flushvp = vp;
        if (LFS_SHOULD_CHECKPOINT(fs, fs->lfs_sp->seg_flags)) {
                error = lfs_segwrite(vp->v_mount, SEGM_CKP | SEGM_SYNC);
                fs->lfs_flushvp = NULL;
                KASSERT(fs->lfs_flushvp_fakevref == 0);
                lfs_segunlock(fs);

                /* Make sure that any pending buffers get written */
                mutex_enter(&vp->v_interlock);
                while (vp->v_numoutput > 0) {
                        cv_wait(&vp->v_cv, &vp->v_interlock);
                }
                KASSERT(LIST_FIRST(&vp->v_dirtyblkhd) == NULL);
                KASSERT(vp->v_numoutput == 0);
                mutex_exit(&vp->v_interlock);

                return error;
        }
        sp = fs->lfs_sp;

        flushed = 0;
        if (VPISEMPTY(vp)) {
                lfs_writevnodes(fs, vp->v_mount, sp, VN_EMPTY);
                ++flushed;
        } else if ((ip->i_flag & IN_CLEANING) &&
                  (fs->lfs_sp->seg_flags & SEGM_CLEAN)) {
                ivndebug(vp,"vflush/clean");
                lfs_writevnodes(fs, vp->v_mount, sp, VN_CLEAN);
                ++flushed;
        } else if (lfs_dostats) {
                if (!VPISEMPTY(vp) || (VTOI(vp)->i_flag & IN_ALLMOD))
                        ++lfs_stats.vflush_invoked;
                ivndebug(vp,"vflush");
        }

#ifdef DIAGNOSTIC
        if (vp->v_uflag & VU_DIROP) {
                DLOG((DLOG_VNODE, "lfs_vflush: flushing VU_DIROP\n"));
                /* panic("lfs_vflush: VU_DIROP being flushed...this can\'t happen"); */
        }
#endif

        do {
                loopcount = 0;
                do {
                        if (LIST_FIRST(&vp->v_dirtyblkhd) != NULL) {
                                relock = lfs_writefile(fs, sp, vp);
                                if (relock) {
                                        /*
                                         * Might have to wait for the
                                         * cleaner to run; but we're
                                         * still not done with this vnode.
                                         */
                                        KDASSERT(ip->i_number != LFS_IFILE_INUM);
                                        lfs_writeinode(fs, sp, ip);
                                        mutex_enter(&lfs_lock);
                                        LFS_SET_UINO(ip, IN_MODIFIED);
                                        mutex_exit(&lfs_lock);
                                        lfs_writeseg(fs, sp);
                                        lfs_segunlock(fs);
                                        lfs_segunlock_relock(fs);
                                        goto top;
                                }
                        }
                        /*
                         * If we begin a new segment in the middle of writing
                         * the Ifile, it creates an inconsistent checkpoint,
                         * since the Ifile information for the new segment
                         * is not up-to-date.  Take care of this here by
                         * sending the Ifile through again in case there
                         * are newly dirtied blocks.  But wait, there's more!
                         * This second Ifile write could *also* cross a segment
                         * boundary, if the first one was large.  The second
                         * one is guaranteed to be no more than 8 blocks,
                         * though (two segment blocks and supporting indirects)
                         * so the third write *will not* cross the boundary.
                         */
                        if (vp == fs->lfs_ivnode) {
                                lfs_writefile(fs, sp, vp);
                                lfs_writefile(fs, sp, vp);
                        }
#ifdef DEBUG
                        if (++loopcount > 2)
                                log(LOG_NOTICE, "lfs_vflush: looping count=%d\n", loopcount);
#endif
                } while (lfs_writeinode(fs, sp, ip));
        } while (lfs_writeseg(fs, sp) && ip->i_number == LFS_IFILE_INUM);

        if (lfs_dostats) {
                ++lfs_stats.nwrites;
                if (sp->seg_flags & SEGM_SYNC)
                        ++lfs_stats.nsync_writes;
                if (sp->seg_flags & SEGM_CKP)
                        ++lfs_stats.ncheckpoints;
        }
        /*
         * If we were called from somewhere that has already held the seglock
         * (e.g., lfs_markv()), the lfs_segunlock will not wait for
         * the write to complete because we are still locked.
         * Since lfs_vflush() must return the vnode with no dirty buffers,
         * we must explicitly wait, if that is the case.
         *
         * We compare the iocount against 1, not 0, because it is
         * artificially incremented by lfs_seglock().
         */
        mutex_enter(&lfs_lock);
        if (fs->lfs_seglock > 1) {
                while (fs->lfs_iocount > 1)
                        (void)mtsleep(&fs->lfs_iocount, PRIBIO + 1,
                                     "lfs_vflush", 0, &lfs_lock);
        }
        mutex_exit(&lfs_lock);

        lfs_segunlock(fs);

        /* Wait for these buffers to be recovered by aiodoned */
        mutex_enter(&vp->v_interlock);
        while (vp->v_numoutput > 0) {
                cv_wait(&vp->v_cv, &vp->v_interlock);
        }
        KASSERT(LIST_FIRST(&vp->v_dirtyblkhd) == NULL);
        KASSERT(vp->v_numoutput == 0);
        mutex_exit(&vp->v_interlock);

        fs->lfs_flushvp = NULL;
        KASSERT(fs->lfs_flushvp_fakevref == 0);

        return (0);
}

int
lfs_writevnodes(struct lfs *fs, struct mount *mp, struct segment *sp, int op)
{
        struct inode *ip;
        struct vnode *vp;
        int inodes_written = 0, only_cleaning;
        int error = 0;

        ASSERT_SEGLOCK(fs);
 loop:
        /* start at last (newest) vnode. */
        mutex_enter(&mntvnode_lock);
        TAILQ_FOREACH_REVERSE(vp, &mp->mnt_vnodelist, vnodelst, v_mntvnodes) {
                /*
                 * If the vnode that we are about to sync is no longer
                 * associated with this mount point, start over.
                 */
                if (vp->v_mount != mp) {
                        DLOG((DLOG_VNODE, "lfs_writevnodes: starting over\n"));
                        /*
                         * After this, pages might be busy
                         * due to our own previous putpages.
                         * Start actual segment write here to avoid deadlock.
                         */
                        mutex_exit(&mntvnode_lock);
                        (void)lfs_writeseg(fs, sp);
                        goto loop;
                }

                mutex_enter(&vp->v_interlock);
                if (vp->v_type == VNON || vismarker(vp) ||
                    (vp->v_iflag & VI_CLEAN) != 0) {
                        mutex_exit(&vp->v_interlock);
                        continue;
                }

                ip = VTOI(vp);
                if ((op == VN_DIROP && !(vp->v_uflag & VU_DIROP)) ||
                    (op != VN_DIROP && op != VN_CLEAN &&
                    (vp->v_uflag & VU_DIROP))) {
                        mutex_exit(&vp->v_interlock);
                        vndebug(vp,"dirop");
                        continue;
                }

                if (op == VN_EMPTY && !VPISEMPTY(vp)) {
                        mutex_exit(&vp->v_interlock);
                        vndebug(vp,"empty");
                        continue;
                }

                if (op == VN_CLEAN && ip->i_number != LFS_IFILE_INUM
                   && vp != fs->lfs_flushvp
                   && !(ip->i_flag & IN_CLEANING)) {
                        mutex_exit(&vp->v_interlock);
                        vndebug(vp,"cleaning");
                        continue;
                }

                mutex_exit(&mntvnode_lock);
                if (lfs_vref(vp)) {
                        vndebug(vp,"vref");
                        mutex_enter(&mntvnode_lock);
                        continue;
                }

                only_cleaning = 0;
                /*
                 * Write the inode/file if dirty and it's not the IFILE.
                 */
                if ((ip->i_flag & IN_ALLMOD) || !VPISEMPTY(vp)) {
                        only_cleaning =
                            ((ip->i_flag & IN_ALLMOD) == IN_CLEANING);

                        if (ip->i_number != LFS_IFILE_INUM) {
                                error = lfs_writefile(fs, sp, vp);
                                if (error) {
                                        lfs_vunref(vp);
                                        if (error == EAGAIN) {
                                                /*
                                                 * This error from lfs_putpages
                                                 * indicates we need to drop
                                                 * the segment lock and start
                                                 * over after the cleaner has
                                                 * had a chance to run.
                                                 */
                                                lfs_writeinode(fs, sp, ip);
                                                lfs_writeseg(fs, sp);
                                                if (!VPISEMPTY(vp) &&
                                                    !WRITEINPROG(vp) &&
                                                    !(ip->i_flag & IN_ALLMOD)) {
                                                        mutex_enter(&lfs_lock);
                                                        LFS_SET_UINO(ip, IN_MODIFIED);
                                                        mutex_exit(&lfs_lock);
                                                }
                                                mutex_enter(&mntvnode_lock);
                                                break;
                                        }
                                        error = 0; /* XXX not quite right */
                                        mutex_enter(&mntvnode_lock);
                                        continue;
                                }
                                
                                if (!VPISEMPTY(vp)) {
                                        if (WRITEINPROG(vp)) {
                                                ivndebug(vp,"writevnodes/write2");
                                        } else if (!(ip->i_flag & IN_ALLMOD)) {
                                                mutex_enter(&lfs_lock);
                                                LFS_SET_UINO(ip, IN_MODIFIED);
                                                mutex_exit(&lfs_lock);
                                        }
                                }
                                (void) lfs_writeinode(fs, sp, ip);
                                inodes_written++;
                        }
                }

                if (lfs_clean_vnhead && only_cleaning)
                        lfs_vunref_head(vp);
                else
                        lfs_vunref(vp);

                mutex_enter(&mntvnode_lock);
        }
        mutex_exit(&mntvnode_lock);
        return error;
}

/*
 * Do a checkpoint.
 */
int
lfs_segwrite(struct mount *mp, int flags)
{
        struct buf *bp;
        struct inode *ip;
        struct lfs *fs;
        struct segment *sp;
        struct vnode *vp;
        SEGUSE *segusep;
        int do_ckp, did_ckp, error;
        unsigned n, segleft, maxseg, sn, i, curseg;
        int writer_set = 0;
        int dirty;
        int redo;
        int um_error;
        int loopcount;

        fs = VFSTOUFS(mp)->um_lfs;
        ASSERT_MAYBE_SEGLOCK(fs);

        if (fs->lfs_ronly)
                return EROFS;

        lfs_imtime(fs);

        /*
         * Allocate a segment structure and enough space to hold pointers to
         * the maximum possible number of buffers which can be described in a
         * single summary block.
         */
        do_ckp = LFS_SHOULD_CHECKPOINT(fs, flags);

        lfs_seglock(fs, flags | (do_ckp ? SEGM_CKP : 0));
        sp = fs->lfs_sp;
        if (sp->seg_flags & (SEGM_CLEAN | SEGM_CKP))
                do_ckp = 1;

        /*
         * If lfs_flushvp is non-NULL, we are called from lfs_vflush,
         * in which case we have to flush *all* buffers off of this vnode.
         * We don't care about other nodes, but write any non-dirop nodes
         * anyway in anticipation of another getnewvnode().
         *
         * If we're cleaning we only write cleaning and ifile blocks, and
         * no dirops, since otherwise we'd risk corruption in a crash.
         */
        if (sp->seg_flags & SEGM_CLEAN)
                lfs_writevnodes(fs, mp, sp, VN_CLEAN);
        else if (!(sp->seg_flags & SEGM_FORCE_CKP)) {
                do {
                        um_error = lfs_writevnodes(fs, mp, sp, VN_REG);

                        if (do_ckp || fs->lfs_dirops == 0) {
                                if (!writer_set) {
                                        lfs_writer_enter(fs, "lfs writer");
                                        writer_set = 1;
                                }
                                error = lfs_writevnodes(fs, mp, sp, VN_DIROP);
                                if (um_error == 0)
                                        um_error = error;
                                /* In case writevnodes errored out */
                                lfs_flush_dirops(fs);
                                ((SEGSUM *)(sp->segsum))->ss_flags &= ~(SS_CONT);
                                lfs_finalize_fs_seguse(fs);
                        }
                        if (do_ckp && um_error) {
                                lfs_segunlock_relock(fs);
                                sp = fs->lfs_sp;
                        }
                } while (do_ckp && um_error != 0);
        }

        /*
         * If we are doing a checkpoint, mark everything since the
         * last checkpoint as no longer ACTIVE.
         */
        if (do_ckp || fs->lfs_doifile) {
                segleft = fs->lfs_nseg;
                curseg = 0;
                for (n = 0; n < fs->lfs_segtabsz; n++) {
                        dirty = 0;
                        if (bread(fs->lfs_ivnode, fs->lfs_cleansz + n,
                            fs->lfs_bsize, NOCRED, B_MODIFY, &bp))
                                panic("lfs_segwrite: ifile read");
                        segusep = (SEGUSE *)bp->b_data;
                        maxseg = min(segleft, fs->lfs_sepb);
                        for (i = 0; i < maxseg; i++) {
                                sn = curseg + i;
                                if (sn != dtosn(fs, fs->lfs_curseg) &&
                                    segusep->su_flags & SEGUSE_ACTIVE) {
                                        segusep->su_flags &= ~SEGUSE_ACTIVE;
                                        --fs->lfs_nactive;
                                        ++dirty;
                                }
                                fs->lfs_suflags[fs->lfs_activesb][sn] =
                                        segusep->su_flags;
                                if (fs->lfs_version > 1)
                                        ++segusep;
                                else
                                        segusep = (SEGUSE *)
                                                ((SEGUSE_V1 *)segusep + 1);
                        }

                        if (dirty)
                                error = LFS_BWRITE_LOG(bp); /* Ifile */
                        else
                                brelse(bp, 0);
                        segleft -= fs->lfs_sepb;
                        curseg += fs->lfs_sepb;
                }
        }

        KASSERT(LFS_SEGLOCK_HELD(fs));

        did_ckp = 0;
        if (do_ckp || fs->lfs_doifile) {
                vp = fs->lfs_ivnode;
                vn_lock(vp, LK_EXCLUSIVE);
                loopcount = 0;
                do {
#ifdef DEBUG
                        LFS_ENTER_LOG("pretend", __FILE__, __LINE__, 0, 0, curproc->p_pid);
#endif
                        mutex_enter(&lfs_lock);
                        fs->lfs_flags &= ~LFS_IFDIRTY;
                        mutex_exit(&lfs_lock);

                        ip = VTOI(vp);

                        if (LIST_FIRST(&vp->v_dirtyblkhd) != NULL) {
                                /*
                                 * Ifile has no pages, so we don't need
                                 * to check error return here.
                                 */
                                lfs_writefile(fs, sp, vp);
                                /*
                                 * Ensure the Ifile takes the current segment
                                 * into account.  See comment in lfs_vflush.
                                 */
                                lfs_writefile(fs, sp, vp);
                                lfs_writefile(fs, sp, vp);
                        }

                        if (ip->i_flag & IN_ALLMOD)
                                ++did_ckp;
#if 0
                        redo = (do_ckp ? lfs_writeinode(fs, sp, ip) : 0);
#else
                        redo = lfs_writeinode(fs, sp, ip);
#endif
                        redo += lfs_writeseg(fs, sp);
                        mutex_enter(&lfs_lock);
                        redo += (fs->lfs_flags & LFS_IFDIRTY);
                        mutex_exit(&lfs_lock);
#ifdef DEBUG
                        if (++loopcount > 2)
                                log(LOG_NOTICE, "lfs_segwrite: looping count=%d\n",
                                        loopcount);
#endif
                } while (redo && do_ckp);

                /*
                 * Unless we are unmounting, the Ifile may continue to have
                 * dirty blocks even after a checkpoint, due to changes to
                 * inodes' atime.  If we're checkpointing, it's "impossible"
                 * for other parts of the Ifile to be dirty after the loop
                 * above, since we hold the segment lock.
                 */
                mutex_enter(&vp->v_interlock);
                if (LIST_EMPTY(&vp->v_dirtyblkhd)) {
                        LFS_CLR_UINO(ip, IN_ALLMOD);
                }
#ifdef DIAGNOSTIC
                else if (do_ckp) {
                        int do_panic = 0;
                        LIST_FOREACH(bp, &vp->v_dirtyblkhd, b_vnbufs) {
                                if (bp->b_lblkno < fs->lfs_cleansz +
                                    fs->lfs_segtabsz &&
                                    !(bp->b_flags & B_GATHERED)) {
                                        printf("ifile lbn %ld still dirty (flags %lx)\n",
                                                (long)bp->b_lblkno,
                                                (long)bp->b_flags);
                                        ++do_panic;
                                }
                        }
                        if (do_panic)
                                panic("dirty blocks");
                }
#endif
                mutex_exit(&vp->v_interlock);
                VOP_UNLOCK(vp, 0);
        } else {
                (void) lfs_writeseg(fs, sp);
        }

        /* Note Ifile no longer needs to be written */
        fs->lfs_doifile = 0;
        if (writer_set)
                lfs_writer_leave(fs);

        /*
         * If we didn't write the Ifile, we didn't really do anything.
         * That means that (1) there is a checkpoint on disk and (2)
         * nothing has changed since it was written.
         *
         * Take the flags off of the segment so that lfs_segunlock
         * doesn't have to write the superblock either.
         */
        if (do_ckp && !did_ckp) {
                sp->seg_flags &= ~SEGM_CKP;
        }

        if (lfs_dostats) {
                ++lfs_stats.nwrites;
                if (sp->seg_flags & SEGM_SYNC)
                        ++lfs_stats.nsync_writes;
                if (sp->seg_flags & SEGM_CKP)
                        ++lfs_stats.ncheckpoints;
        }
        lfs_segunlock(fs);
        return (0);
}

/*
 * Write the dirty blocks associated with a vnode.
 */
int
lfs_writefile(struct lfs *fs, struct segment *sp, struct vnode *vp)
{
        struct finfo *fip;
        struct inode *ip;
        int i, frag;
        int error;

        ASSERT_SEGLOCK(fs);
        error = 0;
        ip = VTOI(vp);

        fip = sp->fip;
        lfs_acquire_finfo(fs, ip->i_number, ip->i_gen);

        if (vp->v_uflag & VU_DIROP)
                ((SEGSUM *)(sp->segsum))->ss_flags |= (SS_DIROP|SS_CONT);

        if (sp->seg_flags & SEGM_CLEAN) {
                lfs_gather(fs, sp, vp, lfs_match_fake);
                /*
                 * For a file being flushed, we need to write *all* blocks.
                 * This means writing the cleaning blocks first, and then
                 * immediately following with any non-cleaning blocks.
                 * The same is true of the Ifile since checkpoints assume
                 * that all valid Ifile blocks are written.
                 */
                if (IS_FLUSHING(fs, vp) || vp == fs->lfs_ivnode) {
                        lfs_gather(fs, sp, vp, lfs_match_data);
                        /*
                         * Don't call VOP_PUTPAGES: if we're flushing,
                         * we've already done it, and the Ifile doesn't
                         * use the page cache.
                         */
                }
        } else {
                lfs_gather(fs, sp, vp, lfs_match_data);
                /*
                 * If we're flushing, we've already called VOP_PUTPAGES
                 * so don't do it again.  Otherwise, we want to write
                 * everything we've got.
                 */
                if (!IS_FLUSHING(fs, vp)) {
                        mutex_enter(&vp->v_interlock);
                        error = VOP_PUTPAGES(vp, 0, 0,
                                PGO_CLEANIT | PGO_ALLPAGES | PGO_LOCKED);
                }
        }

        /*
         * It may not be necessary to write the meta-data blocks at this point,
         * as the roll-forward recovery code should be able to reconstruct the
         * list.
         *
         * We have to write them anyway, though, under two conditions: (1) the
         * vnode is being flushed (for reuse by vinvalbuf); or (2) we are
         * checkpointing.
         *
         * BUT if we are cleaning, we might have indirect blocks that refer to
         * new blocks not being written yet, in addition to fragments being
         * moved out of a cleaned segment.  If that is the case, don't
         * write the indirect blocks, or the finfo will have a small block
         * in the middle of it!
         * XXX in this case isn't the inode size wrong too?
         */
        frag = 0;
        if (sp->seg_flags & SEGM_CLEAN) {
                for (i = 0; i < NDADDR; i++)
                        if (ip->i_lfs_fragsize[i] > 0 &&
                            ip->i_lfs_fragsize[i] < fs->lfs_bsize)
                                ++frag;
        }
#ifdef DIAGNOSTIC
        if (frag > 1)
                panic("lfs_writefile: more than one fragment!");
#endif
        if (IS_FLUSHING(fs, vp) ||
            (frag == 0 && (lfs_writeindir || (sp->seg_flags & SEGM_CKP)))) {
                lfs_gather(fs, sp, vp, lfs_match_indir);
                lfs_gather(fs, sp, vp, lfs_match_dindir);
                lfs_gather(fs, sp, vp, lfs_match_tindir);
        }
        fip = sp->fip;
        lfs_release_finfo(fs);

        return error;
}

/*
 * Update segment accounting to reflect this inode's change of address.
 */
static int
lfs_update_iaddr(struct lfs *fs, struct segment *sp, struct inode *ip, daddr_t ndaddr)
{
        struct buf *bp;
        daddr_t daddr;
        IFILE *ifp;
        SEGUSE *sup;
        ino_t ino;
        int redo_ifile, error;
        u_int32_t sn;

        redo_ifile = 0;

        /*
         * If updating the ifile, update the super-block.  Update the disk
         * address and access times for this inode in the ifile.
         */
        ino = ip->i_number;
        if (ino == LFS_IFILE_INUM) {
                daddr = fs->lfs_idaddr;
                fs->lfs_idaddr = dbtofsb(fs, ndaddr);
        } else {
                LFS_IENTRY(ifp, fs, ino, bp);
                daddr = ifp->if_daddr;
                ifp->if_daddr = dbtofsb(fs, ndaddr);
                error = LFS_BWRITE_LOG(bp); /* Ifile */
        }

        /*
         * If this is the Ifile and lfs_offset is set to the first block
         * in the segment, dirty the new segment's accounting block
         * (XXX should already be dirty?) and tell the caller to do it again.
         */
        if (ip->i_number == LFS_IFILE_INUM) {
                sn = dtosn(fs, fs->lfs_offset);
                if (sntod(fs, sn) + btofsb(fs, fs->lfs_sumsize) ==
                    fs->lfs_offset) {
                        LFS_SEGENTRY(sup, fs, sn, bp);
                        KASSERT(bp->b_oflags & BO_DELWRI);
                        LFS_WRITESEGENTRY(sup, fs, sn, bp);
                        /* fs->lfs_flags |= LFS_IFDIRTY; */
                        redo_ifile |= 1;
                }
        }

        /*
         * The inode's last address should not be in the current partial
         * segment, except under exceptional circumstances (lfs_writevnodes
         * had to start over, and in the meantime more blocks were written
         * to a vnode).  Both inodes will be accounted to this segment
         * in lfs_writeseg so we need to subtract the earlier version
         * here anyway.  The segment count can temporarily dip below
         * zero here; keep track of how many duplicates we have in
         * "dupino" so we don't panic below.
         */
        if (daddr >= fs->lfs_lastpseg && daddr <= fs->lfs_offset) {
                ++sp->ndupino;
                DLOG((DLOG_SEG, "lfs_writeinode: last inode addr in current pseg "
                      "(ino %d daddr 0x%llx) ndupino=%d\n", ino,
                      (long long)daddr, sp->ndupino));
        }
        /*
         * Account the inode: it no longer belongs to its former segment,
         * though it will not belong to the new segment until that segment
         * is actually written.
         */
        if (daddr != LFS_UNUSED_DADDR) {
                u_int32_t oldsn = dtosn(fs, daddr);
#ifdef DIAGNOSTIC
                int ndupino = (sp->seg_number == oldsn) ? sp->ndupino : 0;
#endif
                LFS_SEGENTRY(sup, fs, oldsn, bp);
#ifdef DIAGNOSTIC
                if (sup->su_nbytes +
                    sizeof (struct ufs1_dinode) * ndupino
                      < sizeof (struct ufs1_dinode)) {
                        printf("lfs_writeinode: negative bytes "
                               "(segment %" PRIu32 " short by %d, "
                               "oldsn=%" PRIu32 ", cursn=%" PRIu32
                               ", daddr=%" PRId64 ", su_nbytes=%u, "
                               "ndupino=%d)\n",
                               dtosn(fs, daddr),
                               (int)sizeof (struct ufs1_dinode) *
                                   (1 - sp->ndupino) - sup->su_nbytes,
                               oldsn, sp->seg_number, daddr,
                               (unsigned int)sup->su_nbytes,
                               sp->ndupino);
                        panic("lfs_writeinode: negative bytes");
                        sup->su_nbytes = sizeof (struct ufs1_dinode);
                }
#endif
                DLOG((DLOG_SU, "seg %d -= %d for ino %d inode\n",
                      dtosn(fs, daddr), sizeof (struct ufs1_dinode), ino));
                sup->su_nbytes -= sizeof (struct ufs1_dinode);
                redo_ifile |=
                        (ino == LFS_IFILE_INUM && !(bp->b_flags & B_GATHERED));
                if (redo_ifile) {
                        mutex_enter(&lfs_lock);
                        fs->lfs_flags |= LFS_IFDIRTY;
                        mutex_exit(&lfs_lock);
                        /* Don't double-account */
                        fs->lfs_idaddr = 0x0;
                }
                LFS_WRITESEGENTRY(sup, fs, oldsn, bp); /* Ifile */
        }

        return redo_ifile;
}

int
lfs_writeinode(struct lfs *fs, struct segment *sp, struct inode *ip)
{
        struct buf *bp;
        struct ufs1_dinode *cdp;
        daddr_t daddr;
        int32_t *daddrp;        /* XXX ondisk32 */
        int i, ndx;
        int redo_ifile = 0;
        int gotblk = 0;
        int count;

        ASSERT_SEGLOCK(fs);
        if (!(ip->i_flag & IN_ALLMOD))
                return (0);

        /* Can't write ifile when writer is not set */
        KASSERT(ip->i_number != LFS_IFILE_INUM || fs->lfs_writer > 0 ||
                (sp->seg_flags & SEGM_CLEAN));

        /*
         * If this is the Ifile, see if writing it here will generate a
         * temporary misaccounting.  If it will, do the accounting and write
         * the blocks, postponing the inode write until the accounting is
         * solid.
         */
        count = 0;
        while (ip->i_number == LFS_IFILE_INUM) {
                int redo = 0;

                if (sp->idp == NULL && sp->ibp == NULL &&
                    (sp->seg_bytes_left < fs->lfs_ibsize ||
                     sp->sum_bytes_left < sizeof(int32_t))) {
                        (void) lfs_writeseg(fs, sp);
                        continue;
                }

                /* Look for dirty Ifile blocks */
                LIST_FOREACH(bp, &fs->lfs_ivnode->v_dirtyblkhd, b_vnbufs) {
                        if (!(bp->b_flags & B_GATHERED)) {
                                redo = 1;
                                break;
                        }
                }

                if (redo == 0)
                        redo = lfs_update_iaddr(fs, sp, ip, 0x0);
                if (redo == 0)
                        break;

                if (sp->idp) {
                        sp->idp->di_inumber = 0;
                        sp->idp = NULL;
                }
                ++count;
                if (count > 2)
                        log(LOG_NOTICE, "lfs_writeinode: looping count=%d\n", count);
                lfs_writefile(fs, sp, fs->lfs_ivnode);
        }

        /* Allocate a new inode block if necessary. */
        if ((ip->i_number != LFS_IFILE_INUM || sp->idp == NULL) &&
            sp->ibp == NULL) {
                /* Allocate a new segment if necessary. */
                if (sp->seg_bytes_left < fs->lfs_ibsize ||
                    sp->sum_bytes_left < sizeof(int32_t))
                        (void) lfs_writeseg(fs, sp);

                /* Get next inode block. */
                daddr = fs->lfs_offset;
                fs->lfs_offset += btofsb(fs, fs->lfs_ibsize);
                sp->ibp = *sp->cbpp++ =
                        getblk(VTOI(fs->lfs_ivnode)->i_devvp,
                            fsbtodb(fs, daddr), fs->lfs_ibsize, 0, 0);
                gotblk++;

                /* Zero out inode numbers */
                for (i = 0; i < INOPB(fs); ++i)
                        ((struct ufs1_dinode *)sp->ibp->b_data)[i].di_inumber =
                            0;

                ++sp->start_bpp;
                fs->lfs_avail -= btofsb(fs, fs->lfs_ibsize);
                /* Set remaining space counters. */
                sp->seg_bytes_left -= fs->lfs_ibsize;
                sp->sum_bytes_left -= sizeof(int32_t);
                ndx = fs->lfs_sumsize / sizeof(int32_t) -
                        sp->ninodes / INOPB(fs) - 1;
                ((int32_t *)(sp->segsum))[ndx] = daddr;
        }

        /* Check VU_DIROP in case there is a new file with no data blocks */
        if (ITOV(ip)->v_uflag & VU_DIROP)
                ((SEGSUM *)(sp->segsum))->ss_flags |= (SS_DIROP|SS_CONT);

        /* Update the inode times and copy the inode onto the inode page. */
        /* XXX kludge --- don't redirty the ifile just to put times on it */
        if (ip->i_number != LFS_IFILE_INUM)
                LFS_ITIMES(ip, NULL, NULL, NULL);

        /*
         * If this is the Ifile, and we've already written the Ifile in this
         * partial segment, just overwrite it (it's not on disk yet) and
         * continue.
         *
         * XXX we know that the bp that we get the second time around has
         * already been gathered.
         */
        if (ip->i_number == LFS_IFILE_INUM && sp->idp) {
                *(sp->idp) = *ip->i_din.ffs1_din;
                ip->i_lfs_osize = ip->i_size;
                return 0;
        }

        bp = sp->ibp;
        cdp = ((struct ufs1_dinode *)bp->b_data) + (sp->ninodes % INOPB(fs));
        *cdp = *ip->i_din.ffs1_din;

        /*
         * If cleaning, link counts and directory file sizes cannot change,
         * since those would be directory operations---even if the file
         * we are writing is marked VU_DIROP we should write the old values.
         * If we're not cleaning, of course, update the values so we get
         * current values the next time we clean.
         */
        if (sp->seg_flags & SEGM_CLEAN) {
                if (ITOV(ip)->v_uflag & VU_DIROP) {
                        cdp->di_nlink = ip->i_lfs_odnlink;
                        /* if (ITOV(ip)->v_type == VDIR) */
                        cdp->di_size = ip->i_lfs_osize;
                }
        } else {
                ip->i_lfs_odnlink = cdp->di_nlink;
                ip->i_lfs_osize = ip->i_size;
        }
                

        /* We can finish the segment accounting for truncations now */
        lfs_finalize_ino_seguse(fs, ip);

        /*
         * If we are cleaning, ensure that we don't write UNWRITTEN disk
         * addresses to disk; possibly change the on-disk record of
         * the inode size, either by reverting to the previous size
         * (in the case of cleaning) or by verifying the inode's block
         * holdings (in the case of files being allocated as they are being
         * written).
         * XXX By not writing UNWRITTEN blocks, we are making the lfs_avail
         * XXX count on disk wrong by the same amount.  We should be
         * XXX able to "borrow" from lfs_avail and return it after the
         * XXX Ifile is written.  See also in lfs_writeseg.
         */

        /* Check file size based on highest allocated block */
        if (((ip->i_ffs1_mode & IFMT) == IFREG ||
             (ip->i_ffs1_mode & IFMT) == IFDIR) &&
            ip->i_size > ((ip->i_lfs_hiblk + 1) << fs->lfs_bshift)) {
                cdp->di_size = (ip->i_lfs_hiblk + 1) << fs->lfs_bshift;
                DLOG((DLOG_SEG, "lfs_writeinode: ino %d size %" PRId64 " -> %"
                      PRId64 "\n", (int)ip->i_number, ip->i_size, cdp->di_size));
        }
        if (ip->i_lfs_effnblks != ip->i_ffs1_blocks) {
                DLOG((DLOG_SEG, "lfs_writeinode: cleansing ino %d eff %d != nblk %d)"
                      " at %x\n", ip->i_number, ip->i_lfs_effnblks,
                      ip->i_ffs1_blocks, fs->lfs_offset));
                for (daddrp = cdp->di_db; daddrp < cdp->di_ib + NIADDR;
                     daddrp++) {
                        if (*daddrp == UNWRITTEN) {
                                DLOG((DLOG_SEG, "lfs_writeinode: wiping UNWRITTEN\n"));
                                *daddrp = 0;
                        }
                }
        }

#ifdef DIAGNOSTIC
        /*
         * Check dinode held blocks against dinode size.
         * This should be identical to the check in lfs_vget().
         */
        for (i = (cdp->di_size + fs->lfs_bsize - 1) >> fs->lfs_bshift;
             i < NDADDR; i++) {
                KASSERT(i >= 0);
                if ((cdp->di_mode & IFMT) == IFLNK)
                        continue;
                if (((cdp->di_mode & IFMT) == IFBLK ||
                     (cdp->di_mode & IFMT) == IFCHR) && i == 0)
                        continue;
                if (cdp->di_db[i] != 0) {
# ifdef DEBUG
                        lfs_dump_dinode(cdp);
# endif
                        panic("writing inconsistent inode");
                }
        }
#endif /* DIAGNOSTIC */

        if (ip->i_flag & IN_CLEANING)
                LFS_CLR_UINO(ip, IN_CLEANING);
        else {
                /* XXX IN_ALLMOD */
                LFS_CLR_UINO(ip, IN_ACCESSED | IN_ACCESS | IN_CHANGE |
                             IN_UPDATE | IN_MODIFY);
                if (ip->i_lfs_effnblks == ip->i_ffs1_blocks)
                        LFS_CLR_UINO(ip, IN_MODIFIED);
                else {
                        DLOG((DLOG_VNODE, "lfs_writeinode: ino %d: real "
                            "blks=%d, eff=%d\n", ip->i_number,
                            ip->i_ffs1_blocks, ip->i_lfs_effnblks));
                }
        }

        if (ip->i_number == LFS_IFILE_INUM) {
                /* We know sp->idp == NULL */
                sp->idp = ((struct ufs1_dinode *)bp->b_data) +
                        (sp->ninodes % INOPB(fs));

                /* Not dirty any more */
                mutex_enter(&lfs_lock);
                fs->lfs_flags &= ~LFS_IFDIRTY;
                mutex_exit(&lfs_lock);
        }

        if (gotblk) {
                mutex_enter(&bufcache_lock);
                LFS_LOCK_BUF(bp);
                brelsel(bp, 0);
                mutex_exit(&bufcache_lock);
        }

        /* Increment inode count in segment summary block. */
        ++((SEGSUM *)(sp->segsum))->ss_ninos;

        /* If this page is full, set flag to allocate a new page. */
        if (++sp->ninodes % INOPB(fs) == 0)
                sp->ibp = NULL;

        redo_ifile = lfs_update_iaddr(fs, sp, ip, bp->b_blkno);

        KASSERT(redo_ifile == 0);
        return (redo_ifile);
}

int
lfs_gatherblock(struct segment *sp, struct buf *bp, kmutex_t *mptr)
{
        struct lfs *fs;
        int vers;
        int j, blksinblk;

        ASSERT_SEGLOCK(sp->fs);
        /*
         * If full, finish this segment.  We may be doing I/O, so
         * release and reacquire the splbio().
         */
#ifdef DIAGNOSTIC
        if (sp->vp == NULL)
                panic ("lfs_gatherblock: Null vp in segment");
#endif
        fs = sp->fs;
        blksinblk = howmany(bp->b_bcount, fs->lfs_bsize);
        if (sp->sum_bytes_left < sizeof(int32_t) * blksinblk ||
            sp->seg_bytes_left < bp->b_bcount) {
                if (mptr)
                        mutex_exit(mptr);
                lfs_updatemeta(sp);

                vers = sp->fip->fi_version;
                (void) lfs_writeseg(fs, sp);

                /* Add the current file to the segment summary. */
                lfs_acquire_finfo(fs, VTOI(sp->vp)->i_number, vers);

                if (mptr)
                        mutex_enter(mptr);
                return (1);
        }

        if (bp->b_flags & B_GATHERED) {
                DLOG((DLOG_SEG, "lfs_gatherblock: already gathered! Ino %d,"
                      " lbn %" PRId64 "\n",
                      sp->fip->fi_ino, bp->b_lblkno));
                return (0);
        }

        /* Insert into the buffer list, update the FINFO block. */
        bp->b_flags |= B_GATHERED;

        *sp->cbpp++ = bp;
        for (j = 0; j < blksinblk; j++) {
                sp->fip->fi_blocks[sp->fip->fi_nblocks++] = bp->b_lblkno + j;
                /* This block's accounting moves from lfs_favail to lfs_avail */
                lfs_deregister_block(sp->vp, bp->b_lblkno + j);
        }

        sp->sum_bytes_left -= sizeof(int32_t) * blksinblk;
        sp->seg_bytes_left -= bp->b_bcount;
        return (0);
}

int
lfs_gather(struct lfs *fs, struct segment *sp, struct vnode *vp,
    int (*match)(struct lfs *, struct buf *))
{
        struct buf *bp, *nbp;
        int count = 0;

        ASSERT_SEGLOCK(fs);
        if (vp->v_type == VBLK)
                return 0;
        KASSERT(sp->vp == NULL);
        sp->vp = vp;
        mutex_enter(&bufcache_lock);

#ifndef LFS_NO_BACKBUF_HACK
/* This is a hack to see if ordering the blocks in LFS makes a difference. */
# define        BUF_OFFSET      \
        (((char *)&LIST_NEXT(bp, b_vnbufs)) - (char *)bp)
# define        BACK_BUF(BP)    \
        ((struct buf *)(((char *)(BP)->b_vnbufs.le_prev) - BUF_OFFSET))
# define        BEG_OF_LIST     \
        ((struct buf *)(((char *)&LIST_FIRST(&vp->v_dirtyblkhd)) - BUF_OFFSET))

loop:
        /* Find last buffer. */
        for (bp = LIST_FIRST(&vp->v_dirtyblkhd);
             bp && LIST_NEXT(bp, b_vnbufs) != NULL;
             bp = LIST_NEXT(bp, b_vnbufs))
                /* nothing */;
        for (; bp && bp != BEG_OF_LIST; bp = nbp) {
                nbp = BACK_BUF(bp);
#else /* LFS_NO_BACKBUF_HACK */
loop:
        for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                nbp = LIST_NEXT(bp, b_vnbufs);
#endif /* LFS_NO_BACKBUF_HACK */
                if ((bp->b_cflags & BC_BUSY) != 0 ||
                    (bp->b_flags & B_GATHERED) != 0 || !match(fs, bp)) {
#ifdef DEBUG
                        if (vp == fs->lfs_ivnode &&
                            (bp->b_cflags & BC_BUSY) != 0 &&
                            (bp->b_flags & B_GATHERED) == 0)
                                log(LOG_NOTICE, "lfs_gather: ifile lbn %"
                                      PRId64 " busy (%x) at 0x%x",
                                      bp->b_lblkno, bp->b_flags,
                                      (unsigned)fs->lfs_offset);
#endif
                        continue;
                }
#ifdef DIAGNOSTIC
# ifdef LFS_USE_B_INVAL
                if ((bp->b_flags & BC_INVAL) != 0 && bp->b_iodone == NULL) {
                        DLOG((DLOG_SEG, "lfs_gather: lbn %" PRId64
                              " is BC_INVAL\n", bp->b_lblkno));
                        VOP_PRINT(bp->b_vp);
                }
# endif /* LFS_USE_B_INVAL */
                if (!(bp->b_oflags & BO_DELWRI))
                        panic("lfs_gather: bp not BO_DELWRI");
                if (!(bp->b_flags & B_LOCKED)) {
                        DLOG((DLOG_SEG, "lfs_gather: lbn %" PRId64
                              " blk %" PRId64 " not B_LOCKED\n",
                              bp->b_lblkno,
                              dbtofsb(fs, bp->b_blkno)));
                        VOP_PRINT(bp->b_vp);
                        panic("lfs_gather: bp not B_LOCKED");
                }
#endif
                if (lfs_gatherblock(sp, bp, &bufcache_lock)) {
                        goto loop;
                }
                count++;
        }
        mutex_exit(&bufcache_lock);
        lfs_updatemeta(sp);
        KASSERT(sp->vp == vp);
        sp->vp = NULL;
        return count;
}

#if DEBUG
# define DEBUG_OOFF(n) do {                                             \
        if (ooff == 0) {                                                \
                DLOG((DLOG_SEG, "lfs_updatemeta[%d]: warning: writing " \
                        "ino %d lbn %" PRId64 " at 0x%" PRIx32          \
                        ", was 0x0 (or %" PRId64 ")\n",                 \
                        (n), ip->i_number, lbn, ndaddr, daddr));        \
        }                                                               \
} while (0)
#else
# define DEBUG_OOFF(n)
#endif

/*
 * Change the given block's address to ndaddr, finding its previous
 * location using ufs_bmaparray().
 *
 * Account for this change in the segment table.
 *
 * called with sp == NULL by roll-forwarding code.
 */
void
lfs_update_single(struct lfs *fs, struct segment *sp,
    struct vnode *vp, daddr_t lbn, int32_t ndaddr, int size)
{
        SEGUSE *sup;
        struct buf *bp;
        struct indir a[NIADDR + 2], *ap;
        struct inode *ip;
        daddr_t daddr, ooff;
        int num, error;
        int bb, osize, obb;

        ASSERT_SEGLOCK(fs);
        KASSERT(sp == NULL || sp->vp == vp);
        ip = VTOI(vp);

        error = ufs_bmaparray(vp, lbn, &daddr, a, &num, NULL, NULL);
        if (error)
                panic("lfs_updatemeta: ufs_bmaparray returned %d", error);

        daddr = (daddr_t)((int32_t)daddr); /* XXX ondisk32 */
        KASSERT(daddr <= LFS_MAX_DADDR);
        if (daddr > 0)
                daddr = dbtofsb(fs, daddr);

        bb = fragstofsb(fs, numfrags(fs, size));
        switch (num) {
            case 0:
                    ooff = ip->i_ffs1_db[lbn];
                    DEBUG_OOFF(0);
                    if (ooff == UNWRITTEN)
                            ip->i_ffs1_blocks += bb;
                    else {
                            /* possible fragment truncation or extension */
                            obb = btofsb(fs, ip->i_lfs_fragsize[lbn]);
                            ip->i_ffs1_blocks += (bb - obb);
                    }
                    ip->i_ffs1_db[lbn] = ndaddr;
                    break;
            case 1:
                    ooff = ip->i_ffs1_ib[a[0].in_off];
                    DEBUG_OOFF(1);
                    if (ooff == UNWRITTEN)
                            ip->i_ffs1_blocks += bb;
                    ip->i_ffs1_ib[a[0].in_off] = ndaddr;
                    break;
            default:
                    ap = &a[num - 1];
                    if (bread(vp, ap->in_lbn, fs->lfs_bsize, NOCRED,
                        B_MODIFY, &bp))
                            panic("lfs_updatemeta: bread bno %" PRId64,
                                  ap->in_lbn);

                    /* XXX ondisk32 */
                    ooff = ((int32_t *)bp->b_data)[ap->in_off];
                    DEBUG_OOFF(num);
                    if (ooff == UNWRITTEN)
                            ip->i_ffs1_blocks += bb;
                    /* XXX ondisk32 */
                    ((int32_t *)bp->b_data)[ap->in_off] = ndaddr;
                    (void) VOP_BWRITE(bp);
        }

        KASSERT(ooff == 0 || ooff == UNWRITTEN || ooff == daddr);

        /* Update hiblk when extending the file */
        if (lbn > ip->i_lfs_hiblk)
                ip->i_lfs_hiblk = lbn;

        /*
         * Though we'd rather it couldn't, this *can* happen right now
         * if cleaning blocks and regular blocks coexist.
         */
        /* KASSERT(daddr < fs->lfs_lastpseg || daddr > ndaddr); */

        /*
         * Update segment usage information, based on old size
         * and location.
         */
        if (daddr > 0) {
                u_int32_t oldsn = dtosn(fs, daddr);
#ifdef DIAGNOSTIC
                int ndupino;

                if (sp && sp->seg_number == oldsn) {
                        ndupino = sp->ndupino;
                } else {
                        ndupino = 0;
                }
#endif
                KASSERT(oldsn < fs->lfs_nseg);
                if (lbn >= 0 && lbn < NDADDR)
                        osize = ip->i_lfs_fragsize[lbn];
                else
                        osize = fs->lfs_bsize;
                LFS_SEGENTRY(sup, fs, oldsn, bp);
#ifdef DIAGNOSTIC
                if (sup->su_nbytes + sizeof (struct ufs1_dinode) * ndupino
                    < osize) {
                        printf("lfs_updatemeta: negative bytes "
                               "(segment %" PRIu32 " short by %" PRId64
                               ")\n", dtosn(fs, daddr),
                               (int64_t)osize -
                               (sizeof (struct ufs1_dinode) * ndupino +
                                sup->su_nbytes));
                        printf("lfs_updatemeta: ino %llu, lbn %" PRId64
                               ", addr = 0x%" PRIx64 "\n",
                               (unsigned long long)ip->i_number, lbn, daddr);
                        printf("lfs_updatemeta: ndupino=%d\n", ndupino);
                        panic("lfs_updatemeta: negative bytes");
                        sup->su_nbytes = osize -
                            sizeof (struct ufs1_dinode) * ndupino;
                }
#endif
                DLOG((DLOG_SU, "seg %" PRIu32 " -= %d for ino %d lbn %" PRId64
                      " db 0x%" PRIx64 "\n",
                      dtosn(fs, daddr), osize,
                      ip->i_number, lbn, daddr));
                sup->su_nbytes -= osize;
                if (!(bp->b_flags & B_GATHERED)) {
                        mutex_enter(&lfs_lock);
                        fs->lfs_flags |= LFS_IFDIRTY;
                        mutex_exit(&lfs_lock);
                }
                LFS_WRITESEGENTRY(sup, fs, oldsn, bp);
        }
        /*
         * Now that this block has a new address, and its old
         * segment no longer owns it, we can forget about its
         * old size.
         */
        if (lbn >= 0 && lbn < NDADDR)
                ip->i_lfs_fragsize[lbn] = size;
}

/*
 * Update the metadata that points to the blocks listed in the FINFO
 * array.
 */
void
lfs_updatemeta(struct segment *sp)
{
        struct buf *sbp;
        struct lfs *fs;
        struct vnode *vp;
        daddr_t lbn;
        int i, nblocks, num;
        int bb;
        int bytesleft, size;

        ASSERT_SEGLOCK(sp->fs);
        vp = sp->vp;
        nblocks = &sp->fip->fi_blocks[sp->fip->fi_nblocks] - sp->start_lbp;
        KASSERT(nblocks >= 0);
        KASSERT(vp != NULL);
        if (nblocks == 0)
                return;

        /*
         * This count may be high due to oversize blocks from lfs_gop_write.
         * Correct for this. (XXX we should be able to keep track of these.)
         */
        fs = sp->fs;
        for (i = 0; i < nblocks; i++) {
                if (sp->start_bpp[i] == NULL) {
                        DLOG((DLOG_SEG, "lfs_updatemeta: nblocks = %d, not %d\n", i, nblocks));
                        nblocks = i;
                        break;
                }
                num = howmany(sp->start_bpp[i]->b_bcount, fs->lfs_bsize);
                KASSERT(sp->start_bpp[i]->b_lblkno >= 0 || num == 1);
                nblocks -= num - 1;
        }

        KASSERT(vp->v_type == VREG ||
           nblocks == &sp->fip->fi_blocks[sp->fip->fi_nblocks] - sp->start_lbp);
        KASSERT(nblocks == sp->cbpp - sp->start_bpp);

        /*
         * Sort the blocks.
         *
         * We have to sort even if the blocks come from the
         * cleaner, because there might be other pending blocks on the
         * same inode...and if we don't sort, and there are fragments
         * present, blocks may be written in the wrong place.
         */
        lfs_shellsort(sp->start_bpp, sp->start_lbp, nblocks, fs->lfs_bsize);

        /*
         * Record the length of the last block in case it's a fragment.
         * If there are indirect blocks present, they sort last.  An
         * indirect block will be lfs_bsize and its presence indicates
         * that you cannot have fragments.
         *
         * XXX This last is a lie.  A cleaned fragment can coexist with
         * XXX a later indirect block.  This will continue to be
         * XXX true until lfs_markv is fixed to do everything with
         * XXX fake blocks (including fake inodes and fake indirect blocks).
         */
        sp->fip->fi_lastlength = ((sp->start_bpp[nblocks - 1]->b_bcount - 1) &
                fs->lfs_bmask) + 1;

        /*
         * Assign disk addresses, and update references to the logical
         * block and the segment usage information.
         */
        for (i = nblocks; i--; ++sp->start_bpp) {
                sbp = *sp->start_bpp;
                lbn = *sp->start_lbp;
                KASSERT(sbp->b_lblkno == lbn);

                sbp->b_blkno = fsbtodb(fs, fs->lfs_offset);

                /*
                 * If we write a frag in the wrong place, the cleaner won't
                 * be able to correctly identify its size later, and the
                 * segment will be uncleanable.  (Even worse, it will assume
                 * that the indirect block that actually ends the list
                 * is of a smaller size!)
                 */
                if ((sbp->b_bcount & fs->lfs_bmask) && i != 0)
                        panic("lfs_updatemeta: fragment is not last block");

                /*
                 * For each subblock in this possibly oversized block,
                 * update its address on disk.
                 */
                KASSERT(lbn >= 0 || sbp->b_bcount == fs->lfs_bsize);
                KASSERT(vp == sbp->b_vp);
                for (bytesleft = sbp->b_bcount; bytesleft > 0;
                     bytesleft -= fs->lfs_bsize) {
                        size = MIN(bytesleft, fs->lfs_bsize);
                        bb = fragstofsb(fs, numfrags(fs, size));
                        lbn = *sp->start_lbp++;
                        lfs_update_single(fs, sp, sp->vp, lbn, fs->lfs_offset,
                            size);
                        fs->lfs_offset += bb;
                }

        }

        /* This inode has been modified */
        LFS_SET_UINO(VTOI(vp), IN_MODIFIED);
}

/*
 * Move lfs_offset to a segment earlier than sn.
 */
int
lfs_rewind(struct lfs *fs, int newsn)
{
        int sn, osn, isdirty;
        struct buf *bp;
        SEGUSE *sup;

        ASSERT_SEGLOCK(fs);

        osn = dtosn(fs, fs->lfs_offset);
        if (osn < newsn)
                return 0;

        /* lfs_avail eats the remaining space in this segment */
        fs->lfs_avail -= fs->lfs_fsbpseg - (fs->lfs_offset - fs->lfs_curseg);

        /* Find a low-numbered segment */
        for (sn = 0; sn < fs->lfs_nseg; ++sn) {
                LFS_SEGENTRY(sup, fs, sn, bp);
                isdirty = sup->su_flags & SEGUSE_DIRTY;
                brelse(bp, 0);

                if (!isdirty)
                        break;
        }
        if (sn == fs->lfs_nseg)
                panic("lfs_rewind: no clean segments");
        if (newsn >= 0 && sn >= newsn)
                return ENOENT;
        fs->lfs_nextseg = sn;
        lfs_newseg(fs);
        fs->lfs_offset = fs->lfs_curseg;

        return 0;
}

/*
 * Start a new partial segment.
 *
 * Return 1 when we entered to a new segment.
 * Otherwise, return 0.
 */
int
lfs_initseg(struct lfs *fs)
{
        struct segment *sp = fs->lfs_sp;
        SEGSUM *ssp;
        struct buf *sbp;        /* buffer for SEGSUM */
        int repeat = 0;         /* return value */

        ASSERT_SEGLOCK(fs);
        /* Advance to the next segment. */
        if (!LFS_PARTIAL_FITS(fs)) {
                SEGUSE *sup;
                struct buf *bp;

                /* lfs_avail eats the remaining space */
                fs->lfs_avail -= fs->lfs_fsbpseg - (fs->lfs_offset -
                                                   fs->lfs_curseg);
                /* Wake up any cleaning procs waiting on this file system. */
                lfs_wakeup_cleaner(fs);
                lfs_newseg(fs);
                repeat = 1;
                fs->lfs_offset = fs->lfs_curseg;

                sp->seg_number = dtosn(fs, fs->lfs_curseg);
                sp->seg_bytes_left = fsbtob(fs, fs->lfs_fsbpseg);

                /*
                 * If the segment contains a superblock, update the offset
                 * and summary address to skip over it.
                 */
                LFS_SEGENTRY(sup, fs, sp->seg_number, bp);
                if (sup->su_flags & SEGUSE_SUPERBLOCK) {
                        fs->lfs_offset += btofsb(fs, LFS_SBPAD);
                        sp->seg_bytes_left -= LFS_SBPAD;
                }
                brelse(bp, 0);
                /* Segment zero could also contain the labelpad */
                if (fs->lfs_version > 1 && sp->seg_number == 0 &&
                    fs->lfs_start < btofsb(fs, LFS_LABELPAD)) {
                        fs->lfs_offset +=
                            btofsb(fs, LFS_LABELPAD) - fs->lfs_start;
                        sp->seg_bytes_left -=
                            LFS_LABELPAD - fsbtob(fs, fs->lfs_start);
                }
        } else {
                sp->seg_number = dtosn(fs, fs->lfs_curseg);
                sp->seg_bytes_left = fsbtob(fs, fs->lfs_fsbpseg -
                                      (fs->lfs_offset - fs->lfs_curseg));
        }
        fs->lfs_lastpseg = fs->lfs_offset;

        /* Record first address of this partial segment */
        if (sp->seg_flags & SEGM_CLEAN) {
                fs->lfs_cleanint[fs->lfs_cleanind] = fs->lfs_offset;
                if (++fs->lfs_cleanind >= LFS_MAX_CLEANIND) {
                        /* "1" is the artificial inc in lfs_seglock */
                        mutex_enter(&lfs_lock);
                        while (fs->lfs_iocount > 1) {
                                mtsleep(&fs->lfs_iocount, PRIBIO + 1,
                                    "lfs_initseg", 0, &lfs_lock);
                        }
                        mutex_exit(&lfs_lock);
                        fs->lfs_cleanind = 0;
                }
        }

        sp->fs = fs;
        sp->ibp = NULL;
        sp->idp = NULL;
        sp->ninodes = 0;
        sp->ndupino = 0;

        sp->cbpp = sp->bpp;

        /* Get a new buffer for SEGSUM */
        sbp = lfs_newbuf(fs, VTOI(fs->lfs_ivnode)->i_devvp,
            fsbtodb(fs, fs->lfs_offset), fs->lfs_sumsize, LFS_NB_SUMMARY);

        /* ... and enter it into the buffer list. */
        *sp->cbpp = sbp;
        sp->cbpp++;
        fs->lfs_offset += btofsb(fs, fs->lfs_sumsize);

        sp->start_bpp = sp->cbpp;

        /* Set point to SEGSUM, initialize it. */
        ssp = sp->segsum = sbp->b_data;
        memset(ssp, 0, fs->lfs_sumsize);
        ssp->ss_next = fs->lfs_nextseg;
        ssp->ss_nfinfo = ssp->ss_ninos = 0;
        ssp->ss_magic = SS_MAGIC;

        /* Set pointer to first FINFO, initialize it. */
        sp->fip = (struct finfo *)((char *)sp->segsum + SEGSUM_SIZE(fs));
        sp->fip->fi_nblocks = 0;
        sp->start_lbp = &sp->fip->fi_blocks[0];
        sp->fip->fi_lastlength = 0;

        sp->seg_bytes_left -= fs->lfs_sumsize;
        sp->sum_bytes_left = fs->lfs_sumsize - SEGSUM_SIZE(fs);

        return (repeat);
}

/*
 * Remove SEGUSE_INVAL from all segments.
 */
void
lfs_unset_inval_all(struct lfs *fs)
{
        SEGUSE *sup;
        struct buf *bp;
        int i;

        for (i = 0; i < fs->lfs_nseg; i++) {
                LFS_SEGENTRY(sup, fs, i, bp);
                if (sup->su_flags & SEGUSE_INVAL) {
                        sup->su_flags &= ~SEGUSE_INVAL;
                        LFS_WRITESEGENTRY(sup, fs, i, bp);
                } else
                        brelse(bp, 0);
        }
}

/*
 * Return the next segment to write.
 */
void
lfs_newseg(struct lfs *fs)
{
        CLEANERINFO *cip;
        SEGUSE *sup;
        struct buf *bp;
        int curseg, isdirty, sn, skip_inval;

        ASSERT_SEGLOCK(fs);

        /* Honor LFCNWRAPSTOP */
        mutex_enter(&lfs_lock);
        while (fs->lfs_nextseg < fs->lfs_curseg && fs->lfs_nowrap) {
                if (fs->lfs_wrappass) {
                        log(LOG_NOTICE, "%s: wrappass=%d\n",
                                fs->lfs_fsmnt, fs->lfs_wrappass);
                        fs->lfs_wrappass = 0;
                        break;
                }
                fs->lfs_wrapstatus = LFS_WRAP_WAITING;
                wakeup(&fs->lfs_nowrap);
                log(LOG_NOTICE, "%s: waiting at log wrap\n", fs->lfs_fsmnt);
                mtsleep(&fs->lfs_wrappass, PVFS, "newseg", 10 * hz,
                        &lfs_lock);
        }
        fs->lfs_wrapstatus = LFS_WRAP_GOING;
        mutex_exit(&lfs_lock);

        LFS_SEGENTRY(sup, fs, dtosn(fs, fs->lfs_nextseg), bp);
        DLOG((DLOG_SU, "lfs_newseg: seg %d := 0 in newseg\n",
              dtosn(fs, fs->lfs_nextseg)));
        sup->su_flags |= SEGUSE_DIRTY | SEGUSE_ACTIVE;
        sup->su_nbytes = 0;
        sup->su_nsums = 0;
        sup->su_ninos = 0;
        LFS_WRITESEGENTRY(sup, fs, dtosn(fs, fs->lfs_nextseg), bp);

        LFS_CLEANERINFO(cip, fs, bp);
        --cip->clean;
        ++cip->dirty;
        fs->lfs_nclean = cip->clean;
        LFS_SYNC_CLEANERINFO(cip, fs, bp, 1);

        fs->lfs_lastseg = fs->lfs_curseg;
        fs->lfs_curseg = fs->lfs_nextseg;
        skip_inval = 1;
        for (sn = curseg = dtosn(fs, fs->lfs_curseg) + fs->lfs_interleave;;) {
                sn = (sn + 1) % fs->lfs_nseg;

                if (sn == curseg) {
                        if (skip_inval)
                                skip_inval = 0;
                        else
                                panic("lfs_nextseg: no clean segments");
                }
                LFS_SEGENTRY(sup, fs, sn, bp);
                isdirty = sup->su_flags & (SEGUSE_DIRTY | (skip_inval ? SEGUSE_INVAL : 0));
                /* Check SEGUSE_EMPTY as we go along */
                if (isdirty && sup->su_nbytes == 0 &&
                    !(sup->su_flags & SEGUSE_EMPTY))
                        LFS_WRITESEGENTRY(sup, fs, sn, bp);
                else
                        brelse(bp, 0);

                if (!isdirty)
                        break;
        }
        if (skip_inval == 0)
                lfs_unset_inval_all(fs);

        ++fs->lfs_nactive;
        fs->lfs_nextseg = sntod(fs, sn);
        if (lfs_dostats) {
                ++lfs_stats.segsused;
        }
}

static struct buf *
lfs_newclusterbuf(struct lfs *fs, struct vnode *vp, daddr_t addr,
    int n)
{
        struct lfs_cluster *cl;
        struct buf **bpp, *bp;

        ASSERT_SEGLOCK(fs);
        cl = (struct lfs_cluster *)pool_get(&fs->lfs_clpool, PR_WAITOK);
        bpp = (struct buf **)pool_get(&fs->lfs_bpppool, PR_WAITOK);
        memset(cl, 0, sizeof(*cl));
        cl->fs = fs;
        cl->bpp = bpp;
        cl->bufcount = 0;
        cl->bufsize = 0;

        /* If this segment is being written synchronously, note that */
        if (fs->lfs_sp->seg_flags & SEGM_SYNC) {
                cl->flags |= LFS_CL_SYNC;
                cl->seg = fs->lfs_sp;
                ++cl->seg->seg_iocount;
        }

        /* Get an empty buffer header, or maybe one with something on it */
        bp = getiobuf(vp, true);
        bp->b_dev = NODEV;
        bp->b_blkno = bp->b_lblkno = addr;
        bp->b_iodone = lfs_cluster_callback;
        bp->b_private = cl;

        return bp;
}

int
lfs_writeseg(struct lfs *fs, struct segment *sp)
{
        struct buf **bpp, *bp, *cbp, *newbp, *unbusybp;
        SEGUSE *sup;
        SEGSUM *ssp;
        int i;
        int do_again, nblocks, byteoffset;
        size_t el_size;
        struct lfs_cluster *cl;
        u_short ninos;
        struct vnode *devvp;
        char *p = NULL;
        struct vnode *vp;
        int32_t *daddrp;        /* XXX ondisk32 */
        int changed;
        u_int32_t sum;
#ifdef DEBUG
        FINFO *fip;
        int findex;
#endif

        ASSERT_SEGLOCK(fs);

        ssp = (SEGSUM *)sp->segsum;

        /*
         * If there are no buffers other than the segment summary to write,
         * don't do anything.  If we are the end of a dirop sequence, however,
         * write the empty segment summary anyway, to help out the
         * roll-forward agent.
         */
        if ((nblocks = sp->cbpp - sp->bpp) == 1) {
                if ((ssp->ss_flags & (SS_DIROP | SS_CONT)) != SS_DIROP)
                        return 0;
        }

        /* Note if partial segment is being written by the cleaner */
        if (sp->seg_flags & SEGM_CLEAN)
                ssp->ss_flags |= SS_CLEAN;

        devvp = VTOI(fs->lfs_ivnode)->i_devvp;

        /* Update the segment usage information. */
        LFS_SEGENTRY(sup, fs, sp->seg_number, bp);

        /* Loop through all blocks, except the segment summary. */
        for (bpp = sp->bpp; ++bpp < sp->cbpp; ) {
                if ((*bpp)->b_vp != devvp) {
                        sup->su_nbytes += (*bpp)->b_bcount;
                        DLOG((DLOG_SU, "seg %" PRIu32 " += %ld for ino %d"
                              " lbn %" PRId64 " db 0x%" PRIx64 "\n",
                              sp->seg_number, (*bpp)->b_bcount,
                              VTOI((*bpp)->b_vp)->i_number, (*bpp)->b_lblkno,
                              (*bpp)->b_blkno));
                }
        }

#ifdef DEBUG
        /* Check for zero-length and zero-version FINFO entries. */
        fip = (struct finfo *)((char *)ssp + SEGSUM_SIZE(fs));
        for (findex = 0; findex < ssp->ss_nfinfo; findex++) {
                KDASSERT(fip->fi_nblocks > 0);
                KDASSERT(fip->fi_version > 0);
                fip = (FINFO *)((char *)fip + FINFOSIZE +
                        sizeof(int32_t) * fip->fi_nblocks);
        }
#endif /* DEBUG */

        ninos = (ssp->ss_ninos + INOPB(fs) - 1) / INOPB(fs);
        DLOG((DLOG_SU, "seg %d += %d for %d inodes\n",
              sp->seg_number, ssp->ss_ninos * sizeof (struct ufs1_dinode),
              ssp->ss_ninos));
        sup->su_nbytes += ssp->ss_ninos * sizeof (struct ufs1_dinode);
        /* sup->su_nbytes += fs->lfs_sumsize; */
        if (fs->lfs_version == 1)
                sup->su_olastmod = time_second;
        else
                sup->su_lastmod = time_second;
        sup->su_ninos += ninos;
        ++sup->su_nsums;
        fs->lfs_avail -= btofsb(fs, fs->lfs_sumsize);

        do_again = !(bp->b_flags & B_GATHERED);
        LFS_WRITESEGENTRY(sup, fs, sp->seg_number, bp); /* Ifile */

        /*
         * Mark blocks B_BUSY, to prevent then from being changed between
         * the checksum computation and the actual write.
         *
         * If we are cleaning, check indirect blocks for UNWRITTEN, and if
         * there are any, replace them with copies that have UNASSIGNED
         * instead.
         */
        mutex_enter(&bufcache_lock);
        for (bpp = sp->bpp, i = nblocks - 1; i--;) {
                ++bpp;
                bp = *bpp;
                if (bp->b_iodone != NULL) {      /* UBC or malloced buffer */
                        bp->b_cflags |= BC_BUSY;
                        continue;
                }

                while (bp->b_cflags & BC_BUSY) {
                        DLOG((DLOG_SEG, "lfs_writeseg: avoiding potential"
                              " data summary corruption for ino %d, lbn %"
                              PRId64 "\n",
                              VTOI(bp->b_vp)->i_number, bp->b_lblkno));
                        bp->b_cflags |= BC_WANTED;
                        cv_wait(&bp->b_busy, &bufcache_lock);
                }
                bp->b_cflags |= BC_BUSY;
                mutex_exit(&bufcache_lock);
                unbusybp = NULL;

                /*
                 * Check and replace indirect block UNWRITTEN bogosity.
                 * XXX See comment in lfs_writefile.
                 */
                if (bp->b_lblkno < 0 && bp->b_vp != devvp && bp->b_vp &&
                   VTOI(bp->b_vp)->i_ffs1_blocks !=
                   VTOI(bp->b_vp)->i_lfs_effnblks) {
                        DLOG((DLOG_VNODE, "lfs_writeseg: cleansing ino %d (%d != %d)\n",
                              VTOI(bp->b_vp)->i_number,
                              VTOI(bp->b_vp)->i_lfs_effnblks,
                              VTOI(bp->b_vp)->i_ffs1_blocks));
                        /* Make a copy we'll make changes to */
                        newbp = lfs_newbuf(fs, bp->b_vp, bp->b_lblkno,
                                           bp->b_bcount, LFS_NB_IBLOCK);
                        newbp->b_blkno = bp->b_blkno;
                        memcpy(newbp->b_data, bp->b_data,
                               newbp->b_bcount);

                        changed = 0;
                        /* XXX ondisk32 */
                        for (daddrp = (int32_t *)(newbp->b_data);
                             daddrp < (int32_t *)((char *)newbp->b_data +
                                                  newbp->b_bcount); daddrp++) {
                                if (*daddrp == UNWRITTEN) {
                                        ++changed;
                                        *daddrp = 0;
                                }
                        }
                        /*
                         * Get rid of the old buffer.  Don't mark it clean,
                         * though, if it still has dirty data on it.
                         */
                        if (changed) {
                                DLOG((DLOG_SEG, "lfs_writeseg: replacing UNWRITTEN(%d):"
                                      " bp = %p newbp = %p\n", changed, bp,
                                      newbp));
                                *bpp = newbp;
                                bp->b_flags &= ~B_GATHERED;
                                bp->b_error = 0;
                                if (bp->b_iodone != NULL) {
                                        DLOG((DLOG_SEG, "lfs_writeseg: "
                                              "indir bp should not be B_CALL\n"));
                                        biodone(bp);
                                        bp = NULL;
                                } else {
                                        /* Still on free list, leave it there */
                                        unbusybp = bp;
                                        /*
                                         * We have to re-decrement lfs_avail
                                         * since this block is going to come
                                         * back around to us in the next
                                         * segment.
                                         */
                                        fs->lfs_avail -=
                                            btofsb(fs, bp->b_bcount);
                                }
                        } else {
                                lfs_freebuf(fs, newbp);
                        }
                }
                mutex_enter(&bufcache_lock);
                if (unbusybp != NULL) {
                        unbusybp->b_cflags &= ~BC_BUSY;
                        if (unbusybp->b_cflags & BC_WANTED)
                                cv_broadcast(&bp->b_busy);
                }
        }
        mutex_exit(&bufcache_lock);

        /*
         * Compute checksum across data and then across summary; the first
         * block (the summary block) is skipped.  Set the create time here
         * so that it's guaranteed to be later than the inode mod times.
         */
        sum = 0;
        if (fs->lfs_version == 1)
                el_size = sizeof(u_long);
        else
                el_size = sizeof(u_int32_t);
        for (bpp = sp->bpp, i = nblocks - 1; i--; ) {
                ++bpp;
                /* Loop through gop_write cluster blocks */
                for (byteoffset = 0; byteoffset < (*bpp)->b_bcount;
                     byteoffset += fs->lfs_bsize) {
#ifdef LFS_USE_B_INVAL
                        if (((*bpp)->b_cflags & BC_INVAL) != 0 &&
                            (*bpp)->b_iodone != NULL) {
                                if (copyin((void *)(*bpp)->b_saveaddr +
                                           byteoffset, dp, el_size)) {
                                        panic("lfs_writeseg: copyin failed [1]:"
                                                " ino %d blk %" PRId64,
                                                VTOI((*bpp)->b_vp)->i_number,
                                                (*bpp)->b_lblkno);
                                }
                        } else
#endif /* LFS_USE_B_INVAL */
                        {
                                sum = lfs_cksum_part((char *)
                                    (*bpp)->b_data + byteoffset, el_size, sum);
                        }
                }
        }
        if (fs->lfs_version == 1)
                ssp->ss_ocreate = time_second;
        else {
                ssp->ss_create = time_second;
                ssp->ss_serial = ++fs->lfs_serial;
                ssp->ss_ident  = fs->lfs_ident;
        }
        ssp->ss_datasum = lfs_cksum_fold(sum);
        ssp->ss_sumsum = cksum(&ssp->ss_datasum,
            fs->lfs_sumsize - sizeof(ssp->ss_sumsum));

        mutex_enter(&lfs_lock);
        fs->lfs_bfree -= (btofsb(fs, ninos * fs->lfs_ibsize) +
                          btofsb(fs, fs->lfs_sumsize));
        fs->lfs_dmeta += (btofsb(fs, ninos * fs->lfs_ibsize) +
                          btofsb(fs, fs->lfs_sumsize));
        mutex_exit(&lfs_lock);

        /*
         * When we simply write the blocks we lose a rotation for every block
         * written.  To avoid this problem, we cluster the buffers into a
         * chunk and write the chunk.  MAXPHYS is the largest size I/O
         * devices can handle, use that for the size of the chunks.
         *
         * Blocks that are already clusters (from GOP_WRITE), however, we
         * don't bother to copy into other clusters.
         */

#define CHUNKSIZE MAXPHYS

        if (devvp == NULL)
                panic("devvp is NULL");
        for (bpp = sp->bpp, i = nblocks; i;) {
                cbp = lfs_newclusterbuf(fs, devvp, (*bpp)->b_blkno, i);
                cl = cbp->b_private;

                cbp->b_flags |= B_ASYNC;
                cbp->b_cflags |= BC_BUSY;
                cbp->b_bcount = 0;

#if defined(DEBUG) && defined(DIAGNOSTIC)
                if (bpp - sp->bpp > (fs->lfs_sumsize - SEGSUM_SIZE(fs))
                    / sizeof(int32_t)) {
                        panic("lfs_writeseg: real bpp overwrite");
                }
                if (bpp - sp->bpp > segsize(fs) / fs->lfs_fsize) {
                        panic("lfs_writeseg: theoretical bpp overwrite");
                }
#endif

                /*
                 * Construct the cluster.
                 */
                mutex_enter(&lfs_lock);
                ++fs->lfs_iocount;
                mutex_exit(&lfs_lock);
                while (i && cbp->b_bcount < CHUNKSIZE) {
                        bp = *bpp;

                        if (bp->b_bcount > (CHUNKSIZE - cbp->b_bcount))
                                break;
                        if (cbp->b_bcount > 0 && !(cl->flags & LFS_CL_MALLOC))
                                break;

                        /* Clusters from GOP_WRITE are expedited */
                        if (bp->b_bcount > fs->lfs_bsize) {
                                if (cbp->b_bcount > 0)
                                        /* Put in its own buffer */
                                        break;
                                else {
                                        cbp->b_data = bp->b_data;
                                }
                        } else if (cbp->b_bcount == 0) {
                                p = cbp->b_data = lfs_malloc(fs, CHUNKSIZE,
                                                             LFS_NB_CLUSTER);
                                cl->flags |= LFS_CL_MALLOC;
                        }
#ifdef DIAGNOSTIC
                        if (dtosn(fs, dbtofsb(fs, bp->b_blkno +
                                              btodb(bp->b_bcount - 1))) !=
                            sp->seg_number) {
                                printf("blk size %d daddr %" PRIx64
                                    " not in seg %d\n",
                                    bp->b_bcount, bp->b_blkno,
                                    sp->seg_number);
                                panic("segment overwrite");
                        }
#endif

#ifdef LFS_USE_B_INVAL
                        /*
                         * Fake buffers from the cleaner are marked as B_INVAL.
                         * We need to copy the data from user space rather than
                         * from the buffer indicated.
                         * XXX == what do I do on an error?
                         */
                        if ((bp->b_cflags & BC_INVAL) != 0 &&
                            bp->b_iodone != NULL) {
                                if (copyin(bp->b_saveaddr, p, bp->b_bcount))
                                        panic("lfs_writeseg: "
                                            "copyin failed [2]");
                        } else
#endif /* LFS_USE_B_INVAL */
                        if (cl->flags & LFS_CL_MALLOC) {
                                /* copy data into our cluster. */
                                memcpy(p, bp->b_data, bp->b_bcount);
                                p += bp->b_bcount;
                        }

                        cbp->b_bcount += bp->b_bcount;
                        cl->bufsize += bp->b_bcount;

                        bp->b_flags &= ~B_READ;
                        bp->b_error = 0;
                        cl->bpp[cl->bufcount++] = bp;

                        vp = bp->b_vp;
                        mutex_enter(&bufcache_lock);
                        mutex_enter(&vp->v_interlock);
                        bp->b_oflags &= ~(BO_DELWRI | BO_DONE);
                        reassignbuf(bp, vp);
                        vp->v_numoutput++;
                        mutex_exit(&vp->v_interlock);
                        mutex_exit(&bufcache_lock);

                        bpp++;
                        i--;
                }
                if (fs->lfs_sp->seg_flags & SEGM_SYNC)
                        BIO_SETPRIO(cbp, BPRIO_TIMECRITICAL);
                else
                        BIO_SETPRIO(cbp, BPRIO_TIMELIMITED);
                mutex_enter(&devvp->v_interlock);
                devvp->v_numoutput++;
                mutex_exit(&devvp->v_interlock);
                VOP_STRATEGY(devvp, cbp);
                curlwp->l_ru.ru_oublock++;
        }

        if (lfs_dostats) {
                ++lfs_stats.psegwrites;
                lfs_stats.blocktot += nblocks - 1;
                if (fs->lfs_sp->seg_flags & SEGM_SYNC)
                        ++lfs_stats.psyncwrites;
                if (fs->lfs_sp->seg_flags & SEGM_CLEAN) {
                        ++lfs_stats.pcleanwrites;
                        lfs_stats.cleanblocks += nblocks - 1;
                }
        }

        return (lfs_initseg(fs) || do_again);
}

void
lfs_writesuper(struct lfs *fs, daddr_t daddr)
{
        struct buf *bp;
        struct vnode *devvp = VTOI(fs->lfs_ivnode)->i_devvp;
        int s;

        ASSERT_MAYBE_SEGLOCK(fs);
#ifdef DIAGNOSTIC
        KASSERT(fs->lfs_magic == LFS_MAGIC);
#endif
        /*
         * If we can write one superblock while another is in
         * progress, we risk not having a complete checkpoint if we crash.
         * So, block here if a superblock write is in progress.
         */
        mutex_enter(&lfs_lock);
        s = splbio();
        while (fs->lfs_sbactive) {
                mtsleep(&fs->lfs_sbactive, PRIBIO+1, "lfs sb", 0,
                        &lfs_lock);
        }
        fs->lfs_sbactive = daddr;
        splx(s);
        mutex_exit(&lfs_lock);

        /* Set timestamp of this version of the superblock */
        if (fs->lfs_version == 1)
                fs->lfs_otstamp = time_second;
        fs->lfs_tstamp = time_second;

        /* Checksum the superblock and copy it into a buffer. */
        fs->lfs_cksum = lfs_sb_cksum(&(fs->lfs_dlfs));
        bp = lfs_newbuf(fs, devvp,
            fsbtodb(fs, daddr), LFS_SBPAD, LFS_NB_SBLOCK);
        memset((char *)bp->b_data + sizeof(struct dlfs), 0,
            LFS_SBPAD - sizeof(struct dlfs));
        *(struct dlfs *)bp->b_data = fs->lfs_dlfs;

        bp->b_cflags |= BC_BUSY;
        bp->b_flags = (bp->b_flags & ~B_READ) | B_ASYNC;
        bp->b_oflags &= ~(BO_DONE | BO_DELWRI);
        bp->b_error = 0;
        bp->b_iodone = lfs_supercallback;

        if (fs->lfs_sp != NULL && fs->lfs_sp->seg_flags & SEGM_SYNC)
                BIO_SETPRIO(bp, BPRIO_TIMECRITICAL);
        else
                BIO_SETPRIO(bp, BPRIO_TIMELIMITED);
        curlwp->l_ru.ru_oublock++;

        mutex_enter(&devvp->v_interlock);
        devvp->v_numoutput++;
        mutex_exit(&devvp->v_interlock);

        mutex_enter(&lfs_lock);
        ++fs->lfs_iocount;
        mutex_exit(&lfs_lock);
        VOP_STRATEGY(devvp, bp);
}

/*
 * Logical block number match routines used when traversing the dirty block
 * chain.
 */
int
lfs_match_fake(struct lfs *fs, struct buf *bp)
{

        ASSERT_SEGLOCK(fs);
        return LFS_IS_MALLOC_BUF(bp);
}

#if 0
int
lfs_match_real(struct lfs *fs, struct buf *bp)
{

        ASSERT_SEGLOCK(fs);
        return (lfs_match_data(fs, bp) && !lfs_match_fake(fs, bp));
}
#endif

int
lfs_match_data(struct lfs *fs, struct buf *bp)
{

        ASSERT_SEGLOCK(fs);
        return (bp->b_lblkno >= 0);
}

int
lfs_match_indir(struct lfs *fs, struct buf *bp)
{
        daddr_t lbn;

        ASSERT_SEGLOCK(fs);
        lbn = bp->b_lblkno;
        return (lbn < 0 && (-lbn - NDADDR) % NINDIR(fs) == 0);
}

int
lfs_match_dindir(struct lfs *fs, struct buf *bp)
{
        daddr_t lbn;

        ASSERT_SEGLOCK(fs);
        lbn = bp->b_lblkno;
        return (lbn < 0 && (-lbn - NDADDR) % NINDIR(fs) == 1);
}

int
lfs_match_tindir(struct lfs *fs, struct buf *bp)
{
        daddr_t lbn;

        ASSERT_SEGLOCK(fs);
        lbn = bp->b_lblkno;
        return (lbn < 0 && (-lbn - NDADDR) % NINDIR(fs) == 2);
}

static void
lfs_free_aiodone(struct buf *bp)
{
        struct lfs *fs;

        KERNEL_LOCK(1, curlwp);
        fs = bp->b_private;
        ASSERT_NO_SEGLOCK(fs);
        lfs_freebuf(fs, bp);
        KERNEL_UNLOCK_LAST(curlwp);
}

static void
lfs_super_aiodone(struct buf *bp)
{
        struct lfs *fs;

        KERNEL_LOCK(1, curlwp);
        fs = bp->b_private;
        ASSERT_NO_SEGLOCK(fs);
        mutex_enter(&lfs_lock);
        fs->lfs_sbactive = 0;
        if (--fs->lfs_iocount <= 1)
                wakeup(&fs->lfs_iocount);
        wakeup(&fs->lfs_sbactive);
        mutex_exit(&lfs_lock);
        lfs_freebuf(fs, bp);
        KERNEL_UNLOCK_LAST(curlwp);
}

static void
lfs_cluster_aiodone(struct buf *bp)
{
        struct lfs_cluster *cl;
        struct lfs *fs;
        struct buf *tbp, *fbp;
        struct vnode *vp, *devvp, *ovp;
        struct inode *ip;
        int error;

        KERNEL_LOCK(1, curlwp);

        error = bp->b_error;
        cl = bp->b_private;
        fs = cl->fs;
        devvp = VTOI(fs->lfs_ivnode)->i_devvp;
        ASSERT_NO_SEGLOCK(fs);

        /* Put the pages back, and release the buffer */
        while (cl->bufcount--) {
                tbp = cl->bpp[cl->bufcount];
                KASSERT(tbp->b_cflags & BC_BUSY);
                if (error) {
                        tbp->b_error = error;
                }

                /*
                 * We're done with tbp.  If it has not been re-dirtied since
                 * the cluster was written, free it.  Otherwise, keep it on
                 * the locked list to be written again.
                 */
                vp = tbp->b_vp;

                tbp->b_flags &= ~B_GATHERED;

                LFS_BCLEAN_LOG(fs, tbp);

                mutex_enter(&bufcache_lock);
                if (tbp->b_iodone == NULL) {
                        KASSERT(tbp->b_flags & B_LOCKED);
                        bremfree(tbp);
                        if (vp) {
                                mutex_enter(&vp->v_interlock);
                                reassignbuf(tbp, vp);
                                mutex_exit(&vp->v_interlock);
                        }
                        tbp->b_flags |= B_ASYNC; /* for biodone */
                }

                if (((tbp->b_flags | tbp->b_oflags) &
                    (B_LOCKED | BO_DELWRI)) == B_LOCKED)
                        LFS_UNLOCK_BUF(tbp);

                if (tbp->b_oflags & BO_DONE) {
                        DLOG((DLOG_SEG, "blk %d biodone already (flags %lx)\n",
                                cl->bufcount, (long)tbp->b_flags));
                }

                if (tbp->b_iodone != NULL && !LFS_IS_MALLOC_BUF(tbp)) {
                        /*
                         * A buffer from the page daemon.
                         * We use the same iodone as it does,
                         * so we must manually disassociate its
                         * buffers from the vp.
                         */
                        if ((ovp = tbp->b_vp) != NULL) {
                                /* This is just silly */
                                mutex_enter(&ovp->v_interlock);
                                brelvp(tbp);
                                mutex_exit(&ovp->v_interlock);
                                tbp->b_vp = vp;
                                tbp->b_objlock = &vp->v_interlock;
                        }
                        /* Put it back the way it was */
                        tbp->b_flags |= B_ASYNC;
                        /* Master buffers have BC_AGE */
                        if (tbp->b_private == tbp)
                                tbp->b_flags |= BC_AGE;
                }
                mutex_exit(&bufcache_lock);

                biodone(tbp);

                /*
                 * If this is the last block for this vnode, but
                 * there are other blocks on its dirty list,
                 * set IN_MODIFIED/IN_CLEANING depending on what
                 * sort of block.  Only do this for our mount point,
                 * not for, e.g., inode blocks that are attached to
                 * the devvp.
                 * XXX KS - Shouldn't we set *both* if both types
                 * of blocks are present (traverse the dirty list?)
                 */
                mutex_enter(&lfs_lock);
                mutex_enter(&vp->v_interlock);
                if (vp != devvp && vp->v_numoutput == 0 &&
                    (fbp = LIST_FIRST(&vp->v_dirtyblkhd)) != NULL) {
                        ip = VTOI(vp);
                        DLOG((DLOG_SEG, "lfs_cluster_aiodone: mark ino %d\n",
                               ip->i_number));
                        if (LFS_IS_MALLOC_BUF(fbp))
                                LFS_SET_UINO(ip, IN_CLEANING);
                        else
                                LFS_SET_UINO(ip, IN_MODIFIED);
                }
                cv_broadcast(&vp->v_cv);
                mutex_exit(&vp->v_interlock);
                mutex_exit(&lfs_lock);
        }

        /* Fix up the cluster buffer, and release it */
        if (cl->flags & LFS_CL_MALLOC)
                lfs_free(fs, bp->b_data, LFS_NB_CLUSTER);
        putiobuf(bp);

        /* Note i/o done */
        if (cl->flags & LFS_CL_SYNC) {
                if (--cl->seg->seg_iocount == 0)
                        wakeup(&cl->seg->seg_iocount);
        }
        mutex_enter(&lfs_lock);
#ifdef DIAGNOSTIC
        if (fs->lfs_iocount == 0)
                panic("lfs_cluster_aiodone: zero iocount");
#endif
        if (--fs->lfs_iocount <= 1)
                wakeup(&fs->lfs_iocount);
        mutex_exit(&lfs_lock);

        KERNEL_UNLOCK_LAST(curlwp);

        pool_put(&fs->lfs_bpppool, cl->bpp);
        cl->bpp = NULL;
        pool_put(&fs->lfs_clpool, cl);
}

static void
lfs_generic_callback(struct buf *bp, void (*aiodone)(struct buf *))
{
        /* reset b_iodone for when this is a single-buf i/o. */
        bp->b_iodone = aiodone;

        workqueue_enqueue(uvm.aiodone_queue, &bp->b_work, NULL);
}

static void
lfs_cluster_callback(struct buf *bp)
{

        lfs_generic_callback(bp, lfs_cluster_aiodone);
}

void
lfs_supercallback(struct buf *bp)
{

        lfs_generic_callback(bp, lfs_super_aiodone);
}

/*
 * The only buffers that are going to hit these functions are the
 * segment write blocks, or the segment summaries, or the superblocks.
 *
 * All of the above are created by lfs_newbuf, and so do not need to be
 * released via brelse.
 */
void
lfs_callback(struct buf *bp)
{

        lfs_generic_callback(bp, lfs_free_aiodone);
}

/*
 * Shellsort (diminishing increment sort) from Data Structures and
 * Algorithms, Aho, Hopcraft and Ullman, 1983 Edition, page 290;
 * see also Knuth Vol. 3, page 84.  The increments are selected from
 * formula (8), page 95.  Roughly O(N^3/2).
 */
/*
 * This is our own private copy of shellsort because we want to sort
 * two parallel arrays (the array of buffer pointers and the array of
 * logical block numbers) simultaneously.  Note that we cast the array
 * of logical block numbers to a unsigned in this routine so that the
 * negative block numbers (meta data blocks) sort AFTER the data blocks.
 */

void
lfs_shellsort(struct buf **bp_array, int32_t *lb_array, int nmemb, int size)
{
        static int __rsshell_increments[] = { 4, 1, 0 };
        int incr, *incrp, t1, t2;
        struct buf *bp_temp;

#ifdef DEBUG
        incr = 0;
        for (t1 = 0; t1 < nmemb; t1++) {
                for (t2 = 0; t2 * size < bp_array[t1]->b_bcount; t2++) {
                        if (lb_array[incr++] != bp_array[t1]->b_lblkno + t2) {
                                /* dump before panic */
                                printf("lfs_shellsort: nmemb=%d, size=%d\n",
                                    nmemb, size);
                                incr = 0;
                                for (t1 = 0; t1 < nmemb; t1++) {
                                        const struct buf *bp = bp_array[t1];

                                        printf("bp[%d]: lbn=%" PRIu64 ", size=%"
                                            PRIu64 "\n", t1,
                                            (uint64_t)bp->b_bcount,
                                            (uint64_t)bp->b_lblkno);
                                        printf("lbns:");
                                        for (t2 = 0; t2 * size < bp->b_bcount;
                                            t2++) {
                                                printf(" %" PRId32,
                                                    lb_array[incr++]);
                                        }
                                        printf("\n");
                                }
                                panic("lfs_shellsort: inconsistent input");
                        }
                }
        }
#endif

        for (incrp = __rsshell_increments; (incr = *incrp++) != 0;)
                for (t1 = incr; t1 < nmemb; ++t1)
                        for (t2 = t1 - incr; t2 >= 0;)
                                if ((u_int32_t)bp_array[t2]->b_lblkno >
                                    (u_int32_t)bp_array[t2 + incr]->b_lblkno) {
                                        bp_temp = bp_array[t2];
                                        bp_array[t2] = bp_array[t2 + incr];
                                        bp_array[t2 + incr] = bp_temp;
                                        t2 -= incr;
                                } else
                                        break;

        /* Reform the list of logical blocks */
        incr = 0;
        for (t1 = 0; t1 < nmemb; t1++) {
                for (t2 = 0; t2 * size < bp_array[t1]->b_bcount; t2++) {
                        lb_array[incr++] = bp_array[t1]->b_lblkno + t2;
                }
        }
}

/*
 * Call vget with LK_NOWAIT.  If we are the one who holds VI_XLOCK,
 * however, we must press on.  Just fake success in that case.
 */
int
lfs_vref(struct vnode *vp)
{
        int error;
        struct lfs *fs;

        KASSERT(mutex_owned(&vp->v_interlock));

        fs = VTOI(vp)->i_lfs;

        ASSERT_MAYBE_SEGLOCK(fs);

        /*
         * If we return 1 here during a flush, we risk vinvalbuf() not
         * being able to flush all of the pages from this vnode, which
         * will cause it to panic.  So, return 0 if a flush is in progress.
         */
        error = vget(vp, LK_NOWAIT | LK_INTERLOCK);
        if (error == EBUSY && IS_FLUSHING(VTOI(vp)->i_lfs, vp)) {
                ++fs->lfs_flushvp_fakevref;
                return 0;
        }
        return error;
}

/*
 * This is vrele except that we do not want to VOP_INACTIVE this vnode. We
 * inline vrele here to avoid the vn_lock and VOP_INACTIVE call at the end.
 */
void
lfs_vunref(struct vnode *vp)
{
        struct lfs *fs;

        fs = VTOI(vp)->i_lfs;
        ASSERT_MAYBE_SEGLOCK(fs);

        /*
         * Analogous to lfs_vref, if the node is flushing, fake it.
         */
        if (IS_FLUSHING(fs, vp) && fs->lfs_flushvp_fakevref) {
                --fs->lfs_flushvp_fakevref;
                return;
        }

        /* does not call inactive */
        mutex_enter(&vp->v_interlock);
        vrelel(vp, VRELEL_NOINACTIVE);
}

/*
 * We use this when we have vnodes that were loaded in solely for cleaning.
 * There is no reason to believe that these vnodes will be referenced again
 * soon, since the cleaning process is unrelated to normal filesystem
 * activity.  Putting cleaned vnodes at the tail of the list has the effect
 * of flushing the vnode LRU.  So, put vnodes that were loaded only for
 * cleaning at the head of the list, instead.
 */
void
lfs_vunref_head(struct vnode *vp)
{

        ASSERT_SEGLOCK(VTOI(vp)->i_lfs);

        /* does not call inactive, inserts non-held vnode at head of freelist */
        mutex_enter(&vp->v_interlock);
        vrelel(vp, VRELEL_NOINACTIVE | VRELEL_ONHEAD);
}


/*
 * Set up an FINFO entry for a new file.  The fip pointer is assumed to 
 * point at uninitialized space.
 */
void
lfs_acquire_finfo(struct lfs *fs, ino_t ino, int vers)
{
        struct segment *sp = fs->lfs_sp;

        KASSERT(vers > 0);

        if (sp->seg_bytes_left < fs->lfs_bsize ||
            sp->sum_bytes_left < sizeof(struct finfo))
                (void) lfs_writeseg(fs, fs->lfs_sp);
        
        sp->sum_bytes_left -= FINFOSIZE;
        ++((SEGSUM *)(sp->segsum))->ss_nfinfo;
        sp->fip->fi_nblocks = 0;
        sp->fip->fi_ino = ino;
        sp->fip->fi_version = vers;
}

/*
 * Release the FINFO entry, either clearing out an unused entry or
 * advancing us to the next available entry.
 */
void
lfs_release_finfo(struct lfs *fs)
{
        struct segment *sp = fs->lfs_sp;

        if (sp->fip->fi_nblocks != 0) {
                sp->fip = (FINFO*)((char *)sp->fip + FINFOSIZE +
                        sizeof(int32_t) * sp->fip->fi_nblocks);
                sp->start_lbp = &sp->fip->fi_blocks[0];
        } else {
                sp->sum_bytes_left += FINFOSIZE;
                --((SEGSUM *)(sp->segsum))->ss_nfinfo;
        }
}