path: root/sys/ufs/ffs/ffs_softdep.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright 1998, 2000 Marshall Kirk McKusick.
 * Copyright 2009, 2010 Jeffrey W. Roberson <jeff@FreeBSD.org>
 * All rights reserved.
 *
 * The soft updates code is derived from the appendix of a University
 * of Michigan technical report (Gregory R. Ganger and Yale N. Patt,
 * "Soft Updates: A Solution to the Metadata Update Problem in File
 * Systems", CSE-TR-254-95, August 1995).
 *
 * Further information about soft updates can be obtained from:
 *
 *	Marshall Kirk McKusick		http://www.mckusick.com/softdep/
 *	1614 Oxford Street		mckusick@mckusick.com
 *	Berkeley, CA 94709-1608		+1-510-843-9542
 *	USA
 *
 * 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 AUTHORS ``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 AUTHORS 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.
 *
 *	from: @(#)ffs_softdep.c	9.59 (McKusick) 6/21/00
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_ffs.h"
#include "opt_quota.h"
#include "opt_ddb.h"

/*
 * For now we want the safety net that the DEBUG flag provides.
 */
#ifndef DEBUG
#define DEBUG
#endif

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/kdb.h>
#include <sys/kthread.h>
#include <sys/ktr.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/rwlock.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/vnode.h>
#include <sys/conf.h>

#include <ufs/ufs/dir.h>
#include <ufs/ufs/extattr.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ffs/fs.h>
#include <ufs/ffs/softdep.h>
#include <ufs/ffs/ffs_extern.h>
#include <ufs/ufs/ufs_extern.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_object.h>

#include <geom/geom.h>

#include <ddb/ddb.h>

#define	KTR_SUJ	0	/* Define to KTR_SPARE. */

#ifndef SOFTUPDATES

int
softdep_flushfiles(oldmnt, flags, td)
	struct mount *oldmnt;
	int flags;
	struct thread *td;
{

	panic("softdep_flushfiles called");
}

int
softdep_mount(devvp, mp, fs, cred)
	struct vnode *devvp;
	struct mount *mp;
	struct fs *fs;
	struct ucred *cred;
{

	return (0);
}

void
softdep_initialize()
{

	return;
}

void
softdep_uninitialize()
{

	return;
}

void
softdep_unmount(mp)
	struct mount *mp;
{

	panic("softdep_unmount called");
}

void
softdep_setup_sbupdate(ump, fs, bp)
	struct ufsmount *ump;
	struct fs *fs;
	struct buf *bp;
{

	panic("softdep_setup_sbupdate called");
}

void
softdep_setup_inomapdep(bp, ip, newinum, mode)
	struct buf *bp;
	struct inode *ip;
	ino_t newinum;
	int mode;
{

	panic("softdep_setup_inomapdep called");
}

void
softdep_setup_blkmapdep(bp, mp, newblkno, frags, oldfrags)
	struct buf *bp;
	struct mount *mp;
	ufs2_daddr_t newblkno;
	int frags;
	int oldfrags;
{

	panic("softdep_setup_blkmapdep called");
}

void
softdep_setup_allocdirect(ip, lbn, newblkno, oldblkno, newsize, oldsize, bp)
	struct inode *ip;
	ufs_lbn_t lbn;
	ufs2_daddr_t newblkno;
	ufs2_daddr_t oldblkno;
	long newsize;
	long oldsize;
	struct buf *bp;
{
	
	panic("softdep_setup_allocdirect called");
}

void
softdep_setup_allocext(ip, lbn, newblkno, oldblkno, newsize, oldsize, bp)
	struct inode *ip;
	ufs_lbn_t lbn;
	ufs2_daddr_t newblkno;
	ufs2_daddr_t oldblkno;
	long newsize;
	long oldsize;
	struct buf *bp;
{
	
	panic("softdep_setup_allocext called");
}

void
softdep_setup_allocindir_page(ip, lbn, bp, ptrno, newblkno, oldblkno, nbp)
	struct inode *ip;
	ufs_lbn_t lbn;
	struct buf *bp;
	int ptrno;
	ufs2_daddr_t newblkno;
	ufs2_daddr_t oldblkno;
	struct buf *nbp;
{

	panic("softdep_setup_allocindir_page called");
}

void
softdep_setup_allocindir_meta(nbp, ip, bp, ptrno, newblkno)
	struct buf *nbp;
	struct inode *ip;
	struct buf *bp;
	int ptrno;
	ufs2_daddr_t newblkno;
{

	panic("softdep_setup_allocindir_meta called");
}

void
softdep_journal_freeblocks(ip, cred, length, flags)
	struct inode *ip;
	struct ucred *cred;
	off_t length;
	int flags;
{
	
	panic("softdep_journal_freeblocks called");
}

void
softdep_journal_fsync(ip)
	struct inode *ip;
{

	panic("softdep_journal_fsync called");
}

void
softdep_setup_freeblocks(ip, length, flags)
	struct inode *ip;
	off_t length;
	int flags;
{
	
	panic("softdep_setup_freeblocks called");
}

void
softdep_freefile(pvp, ino, mode)
		struct vnode *pvp;
		ino_t ino;
		int mode;
{

	panic("softdep_freefile called");
}

int
softdep_setup_directory_add(bp, dp, diroffset, newinum, newdirbp, isnewblk)
	struct buf *bp;
	struct inode *dp;
	off_t diroffset;
	ino_t newinum;
	struct buf *newdirbp;
	int isnewblk;
{

	panic("softdep_setup_directory_add called");
}

void
softdep_change_directoryentry_offset(bp, dp, base, oldloc, newloc, entrysize)
	struct buf *bp;
	struct inode *dp;
	caddr_t base;
	caddr_t oldloc;
	caddr_t newloc;
	int entrysize;
{

	panic("softdep_change_directoryentry_offset called");
}

void
softdep_setup_remove(bp, dp, ip, isrmdir)
	struct buf *bp;
	struct inode *dp;
	struct inode *ip;
	int isrmdir;
{
	
	panic("softdep_setup_remove called");
}

void
softdep_setup_directory_change(bp, dp, ip, newinum, isrmdir)
	struct buf *bp;
	struct inode *dp;
	struct inode *ip;
	ino_t newinum;
	int isrmdir;
{

	panic("softdep_setup_directory_change called");
}

void
softdep_setup_blkfree(mp, bp, blkno, frags, wkhd)
	struct mount *mp;
	struct buf *bp;
	ufs2_daddr_t blkno;
	int frags;
	struct workhead *wkhd;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_setup_inofree(mp, bp, ino, wkhd)
	struct mount *mp;
	struct buf *bp;
	ino_t ino;
	struct workhead *wkhd;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_setup_unlink(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_setup_link(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_revert_link(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_setup_rmdir(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_revert_rmdir(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_setup_create(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_revert_create(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_setup_mkdir(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_revert_mkdir(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

void
softdep_setup_dotdot_link(dp, ip)
	struct inode *dp;
	struct inode *ip;
{

	panic("%s called", __FUNCTION__);
}

int
softdep_prealloc(vp, waitok)
	struct vnode *vp;
	int waitok;
{

	panic("%s called", __FUNCTION__);
}

int
softdep_journal_lookup(mp, vpp)
	struct mount *mp;
	struct vnode **vpp;
{

	return (ENOENT);
}

void
softdep_change_linkcnt(ip)
	struct inode *ip;
{

	panic("softdep_change_linkcnt called");
}

void 
softdep_load_inodeblock(ip)
	struct inode *ip;
{

	panic("softdep_load_inodeblock called");
}

void
softdep_update_inodeblock(ip, bp, waitfor)
	struct inode *ip;
	struct buf *bp;
	int waitfor;
{

	panic("softdep_update_inodeblock called");
}

int
softdep_fsync(vp)
	struct vnode *vp;	/* the "in_core" copy of the inode */
{

	return (0);
}

void
softdep_fsync_mountdev(vp)
	struct vnode *vp;
{

	return;
}

int
softdep_flushworklist(oldmnt, countp, td)
	struct mount *oldmnt;
	int *countp;
	struct thread *td;
{

	*countp = 0;
	return (0);
}

int
softdep_sync_metadata(struct vnode *vp)
{

	panic("softdep_sync_metadata called");
}

int
softdep_sync_buf(struct vnode *vp, struct buf *bp, int waitfor)
{

	panic("softdep_sync_buf called");
}

int
softdep_slowdown(vp)
	struct vnode *vp;
{

	panic("softdep_slowdown called");
}

int
softdep_request_cleanup(fs, vp, cred, resource)
	struct fs *fs;
	struct vnode *vp;
	struct ucred *cred;
	int resource;
{

	return (0);
}

int
softdep_check_suspend(struct mount *mp,
		      struct vnode *devvp,
		      int softdep_depcnt,
		      int softdep_accdepcnt,
		      int secondary_writes,
		      int secondary_accwrites)
{
	struct bufobj *bo;
	int error;
	
	(void) softdep_depcnt,
	(void) softdep_accdepcnt;

	bo = &devvp->v_bufobj;
	ASSERT_BO_WLOCKED(bo);

	MNT_ILOCK(mp);
	while (mp->mnt_secondary_writes != 0) {
		BO_UNLOCK(bo);
		msleep(&mp->mnt_secondary_writes, MNT_MTX(mp),
		    (PUSER - 1) | PDROP, "secwr", 0);
		BO_LOCK(bo);
		MNT_ILOCK(mp);
	}

	/*
	 * Reasons for needing more work before suspend:
	 * - Dirty buffers on devvp.
	 * - Secondary writes occurred after start of vnode sync loop
	 */
	error = 0;
	if (bo->bo_numoutput > 0 ||
	    bo->bo_dirty.bv_cnt > 0 ||
	    secondary_writes != 0 ||
	    mp->mnt_secondary_writes != 0 ||
	    secondary_accwrites != mp->mnt_secondary_accwrites)
		error = EAGAIN;
	BO_UNLOCK(bo);
	return (error);
}

void
softdep_get_depcounts(struct mount *mp,
		      int *softdepactivep,
		      int *softdepactiveaccp)
{
	(void) mp;
	*softdepactivep = 0;
	*softdepactiveaccp = 0;
}

void
softdep_buf_append(bp, wkhd)
	struct buf *bp;
	struct workhead *wkhd;
{

	panic("softdep_buf_appendwork called");
}

void
softdep_inode_append(ip, cred, wkhd)
	struct inode *ip;
	struct ucred *cred;
	struct workhead *wkhd;
{

	panic("softdep_inode_appendwork called");
}

void
softdep_freework(wkhd)
	struct workhead *wkhd;
{

	panic("softdep_freework called");
}

#else

FEATURE(softupdates, "FFS soft-updates support");

static SYSCTL_NODE(_debug, OID_AUTO, softdep, CTLFLAG_RW, 0,
    "soft updates stats");
static SYSCTL_NODE(_debug_softdep, OID_AUTO, total, CTLFLAG_RW, 0,
    "total dependencies allocated");
static SYSCTL_NODE(_debug_softdep, OID_AUTO, highuse, CTLFLAG_RW, 0,
    "high use dependencies allocated");
static SYSCTL_NODE(_debug_softdep, OID_AUTO, current, CTLFLAG_RW, 0,
    "current dependencies allocated");
static SYSCTL_NODE(_debug_softdep, OID_AUTO, write, CTLFLAG_RW, 0,
    "current dependencies written");

unsigned long dep_current[D_LAST + 1];
unsigned long dep_highuse[D_LAST + 1];
unsigned long dep_total[D_LAST + 1];
unsigned long dep_write[D_LAST + 1];

#define	SOFTDEP_TYPE(type, str, long)					\
    static MALLOC_DEFINE(M_ ## type, #str, long);			\
    SYSCTL_ULONG(_debug_softdep_total, OID_AUTO, str, CTLFLAG_RD,	\
	&dep_total[D_ ## type], 0, "");					\
    SYSCTL_ULONG(_debug_softdep_current, OID_AUTO, str, CTLFLAG_RD, 	\
	&dep_current[D_ ## type], 0, "");				\
    SYSCTL_ULONG(_debug_softdep_highuse, OID_AUTO, str, CTLFLAG_RD, 	\
	&dep_highuse[D_ ## type], 0, "");				\
    SYSCTL_ULONG(_debug_softdep_write, OID_AUTO, str, CTLFLAG_RD, 	\
	&dep_write[D_ ## type], 0, "");

SOFTDEP_TYPE(PAGEDEP, pagedep, "File page dependencies"); 
SOFTDEP_TYPE(INODEDEP, inodedep, "Inode dependencies");
SOFTDEP_TYPE(BMSAFEMAP, bmsafemap,
    "Block or frag allocated from cyl group map");
SOFTDEP_TYPE(NEWBLK, newblk, "New block or frag allocation dependency");
SOFTDEP_TYPE(ALLOCDIRECT, allocdirect, "Block or frag dependency for an inode");
SOFTDEP_TYPE(INDIRDEP, indirdep, "Indirect block dependencies");
SOFTDEP_TYPE(ALLOCINDIR, allocindir, "Block dependency for an indirect block");
SOFTDEP_TYPE(FREEFRAG, freefrag, "Previously used frag for an inode");
SOFTDEP_TYPE(FREEBLKS, freeblks, "Blocks freed from an inode");
SOFTDEP_TYPE(FREEFILE, freefile, "Inode deallocated");
SOFTDEP_TYPE(DIRADD, diradd, "New directory entry");
SOFTDEP_TYPE(MKDIR, mkdir, "New directory");
SOFTDEP_TYPE(DIRREM, dirrem, "Directory entry deleted");
SOFTDEP_TYPE(NEWDIRBLK, newdirblk, "Unclaimed new directory block");
SOFTDEP_TYPE(FREEWORK, freework, "free an inode block");
SOFTDEP_TYPE(FREEDEP, freedep, "track a block free");
SOFTDEP_TYPE(JADDREF, jaddref, "Journal inode ref add");
SOFTDEP_TYPE(JREMREF, jremref, "Journal inode ref remove");
SOFTDEP_TYPE(JMVREF, jmvref, "Journal inode ref move");
SOFTDEP_TYPE(JNEWBLK, jnewblk, "Journal new block");
SOFTDEP_TYPE(JFREEBLK, jfreeblk, "Journal free block");
SOFTDEP_TYPE(JFREEFRAG, jfreefrag, "Journal free frag");
SOFTDEP_TYPE(JSEG, jseg, "Journal segment");
SOFTDEP_TYPE(JSEGDEP, jsegdep, "Journal segment complete");
SOFTDEP_TYPE(SBDEP, sbdep, "Superblock write dependency");
SOFTDEP_TYPE(JTRUNC, jtrunc, "Journal inode truncation");
SOFTDEP_TYPE(JFSYNC, jfsync, "Journal fsync complete");

static MALLOC_DEFINE(M_SENTINEL, "sentinel", "Worklist sentinel");

static MALLOC_DEFINE(M_SAVEDINO, "savedino", "Saved inodes");
static MALLOC_DEFINE(M_JBLOCKS, "jblocks", "Journal block locations");
static MALLOC_DEFINE(M_MOUNTDATA, "softdep", "Softdep per-mount data");

#define M_SOFTDEP_FLAGS	(M_WAITOK)

/* 
 * translate from workitem type to memory type
 * MUST match the defines above, such that memtype[D_XXX] == M_XXX
 */
static struct malloc_type *memtype[] = {
	NULL,
	M_PAGEDEP,
	M_INODEDEP,
	M_BMSAFEMAP,
	M_NEWBLK,
	M_ALLOCDIRECT,
	M_INDIRDEP,
	M_ALLOCINDIR,
	M_FREEFRAG,
	M_FREEBLKS,
	M_FREEFILE,
	M_DIRADD,
	M_MKDIR,
	M_DIRREM,
	M_NEWDIRBLK,
	M_FREEWORK,
	M_FREEDEP,
	M_JADDREF,
	M_JREMREF,
	M_JMVREF,
	M_JNEWBLK,
	M_JFREEBLK,
	M_JFREEFRAG,
	M_JSEG,
	M_JSEGDEP,
	M_SBDEP,
	M_JTRUNC,
	M_JFSYNC,
	M_SENTINEL
};

#define DtoM(type) (memtype[type])

/*
 * Names of malloc types.
 */
#define TYPENAME(type)  \
	((unsigned)(type) <= D_LAST && (unsigned)(type) >= D_FIRST ? \
	memtype[type]->ks_shortdesc : "???")
/*
 * End system adaptation definitions.
 */

#define	DOTDOT_OFFSET	offsetof(struct dirtemplate, dotdot_ino)
#define	DOT_OFFSET	offsetof(struct dirtemplate, dot_ino)

/*
 * Internal function prototypes.
 */
static	void check_clear_deps(struct mount *);
static	void softdep_error(char *, int);
static	int softdep_process_worklist(struct mount *, int);
static	int softdep_waitidle(struct mount *, int);
static	void drain_output(struct vnode *);
static	struct buf *getdirtybuf(struct buf *, struct rwlock *, int);
static	int check_inodedep_free(struct inodedep *);
static	void clear_remove(struct mount *);
static	void clear_inodedeps(struct mount *);
static	void unlinked_inodedep(struct mount *, struct inodedep *);
static	void clear_unlinked_inodedep(struct inodedep *);
static	struct inodedep *first_unlinked_inodedep(struct ufsmount *);
static	int flush_pagedep_deps(struct vnode *, struct mount *,
	    struct diraddhd *);
static	int free_pagedep(struct pagedep *);
static	int flush_newblk_dep(struct vnode *, struct mount *, ufs_lbn_t);
static	int flush_inodedep_deps(struct vnode *, struct mount *, ino_t);
static	int flush_deplist(struct allocdirectlst *, int, int *);
static	int sync_cgs(struct mount *, int);
static	int handle_written_filepage(struct pagedep *, struct buf *, int);
static	int handle_written_sbdep(struct sbdep *, struct buf *);
static	void initiate_write_sbdep(struct sbdep *);
static	void diradd_inode_written(struct diradd *, struct inodedep *);
static	int handle_written_indirdep(struct indirdep *, struct buf *,
	    struct buf**, int);
static	int handle_written_inodeblock(struct inodedep *, struct buf *, int);
static	int jnewblk_rollforward(struct jnewblk *, struct fs *, struct cg *,
	    uint8_t *);
static	int handle_written_bmsafemap(struct bmsafemap *, struct buf *, int);
static	void handle_written_jaddref(struct jaddref *);
static	void handle_written_jremref(struct jremref *);
static	void handle_written_jseg(struct jseg *, struct buf *);
static	void handle_written_jnewblk(struct jnewblk *);
static	void handle_written_jblkdep(struct jblkdep *);
static	void handle_written_jfreefrag(struct jfreefrag *);
static	void complete_jseg(struct jseg *);
static	void complete_jsegs(struct jseg *);
static	void jseg_write(struct ufsmount *ump, struct jseg *, uint8_t *);
static	void jaddref_write(struct jaddref *, struct jseg *, uint8_t *);
static	void jremref_write(struct jremref *, struct jseg *, uint8_t *);
static	void jmvref_write(struct jmvref *, struct jseg *, uint8_t *);
static	void jtrunc_write(struct jtrunc *, struct jseg *, uint8_t *);
static	void jfsync_write(struct jfsync *, struct jseg *, uint8_t *data);
static	void jnewblk_write(struct jnewblk *, struct jseg *, uint8_t *);
static	void jfreeblk_write(struct jfreeblk *, struct jseg *, uint8_t *);
static	void jfreefrag_write(struct jfreefrag *, struct jseg *, uint8_t *);
static	inline void inoref_write(struct inoref *, struct jseg *,
	    struct jrefrec *);
static	void handle_allocdirect_partdone(struct allocdirect *,
	    struct workhead *);
static	struct jnewblk *cancel_newblk(struct newblk *, struct worklist *,
	    struct workhead *);
static	void indirdep_complete(struct indirdep *);
static	int indirblk_lookup(struct mount *, ufs2_daddr_t);
static	void indirblk_insert(struct freework *);
static	void indirblk_remove(struct freework *);
static	void handle_allocindir_partdone(struct allocindir *);
static	void initiate_write_filepage(struct pagedep *, struct buf *);
static	void initiate_write_indirdep(struct indirdep*, struct buf *);
static	void handle_written_mkdir(struct mkdir *, int);
static	int jnewblk_rollback(struct jnewblk *, struct fs *, struct cg *,
	    uint8_t *);
static	void initiate_write_bmsafemap(struct bmsafemap *, struct buf *);
static	void initiate_write_inodeblock_ufs1(struct inodedep *, struct buf *);
static	void initiate_write_inodeblock_ufs2(struct inodedep *, struct buf *);
static	void handle_workitem_freefile(struct freefile *);
static	int handle_workitem_remove(struct dirrem *, int);
static	struct dirrem *newdirrem(struct buf *, struct inode *,
	    struct inode *, int, struct dirrem **);
static	struct indirdep *indirdep_lookup(struct mount *, struct inode *,
	    struct buf *);
static	void cancel_indirdep(struct indirdep *, struct buf *,
	    struct freeblks *);
static	void free_indirdep(struct indirdep *);
static	void free_diradd(struct diradd *, struct workhead *);
static	void merge_diradd(struct inodedep *, struct diradd *);
static	void complete_diradd(struct diradd *);
static	struct diradd *diradd_lookup(struct pagedep *, int);
static	struct jremref *cancel_diradd_dotdot(struct inode *, struct dirrem *,
	    struct jremref *);
static	struct jremref *cancel_mkdir_dotdot(struct inode *, struct dirrem *,
	    struct jremref *);
static	void cancel_diradd(struct diradd *, struct dirrem *, struct jremref *,
	    struct jremref *, struct jremref *);
static	void dirrem_journal(struct dirrem *, struct jremref *, struct jremref *,
	    struct jremref *);
static	void cancel_allocindir(struct allocindir *, struct buf *bp,
	    struct freeblks *, int);
static	int setup_trunc_indir(struct freeblks *, struct inode *,
	    ufs_lbn_t, ufs_lbn_t, ufs2_daddr_t);
static	void complete_trunc_indir(struct freework *);
static	void trunc_indirdep(struct indirdep *, struct freeblks *, struct buf *,
	    int);
static	void complete_mkdir(struct mkdir *);
static	void free_newdirblk(struct newdirblk *);
static	void free_jremref(struct jremref *);
static	void free_jaddref(struct jaddref *);
static	void free_jsegdep(struct jsegdep *);
static	void free_jsegs(struct jblocks *);
static	void rele_jseg(struct jseg *);
static	void free_jseg(struct jseg *, struct jblocks *);
static	void free_jnewblk(struct jnewblk *);
static	void free_jblkdep(struct jblkdep *);
static	void free_jfreefrag(struct jfreefrag *);
static	void free_freedep(struct freedep *);
static	void journal_jremref(struct dirrem *, struct jremref *,
	    struct inodedep *);
static	void cancel_jnewblk(struct jnewblk *, struct workhead *);
static	int cancel_jaddref(struct jaddref *, struct inodedep *,
	    struct workhead *);
static	void cancel_jfreefrag(struct jfreefrag *);
static	inline void setup_freedirect(struct freeblks *, struct inode *,
	    int, int);
static	inline void setup_freeext(struct freeblks *, struct inode *, int, int);
static	inline void setup_freeindir(struct freeblks *, struct inode *, int,
	    ufs_lbn_t, int);
static	inline struct freeblks *newfreeblks(struct mount *, struct inode *);
static	void freeblks_free(struct ufsmount *, struct freeblks *, int);
static	void indir_trunc(struct freework *, ufs2_daddr_t, ufs_lbn_t);
static	ufs2_daddr_t blkcount(struct fs *, ufs2_daddr_t, off_t);
static	int trunc_check_buf(struct buf *, int *, ufs_lbn_t, int, int);
static	void trunc_dependencies(struct inode *, struct freeblks *, ufs_lbn_t,
	    int, int);
static	void trunc_pages(struct inode *, off_t, ufs2_daddr_t, int);
static 	int cancel_pagedep(struct pagedep *, struct freeblks *, int);
static	int deallocate_dependencies(struct buf *, struct freeblks *, int);
static	void newblk_freefrag(struct newblk*);
static	void free_newblk(struct newblk *);
static	void cancel_allocdirect(struct allocdirectlst *,
	    struct allocdirect *, struct freeblks *);
static	int check_inode_unwritten(struct inodedep *);
static	int free_inodedep(struct inodedep *);
static	void freework_freeblock(struct freework *, u_long);
static	void freework_enqueue(struct freework *);
static	int handle_workitem_freeblocks(struct freeblks *, int);
static	int handle_complete_freeblocks(struct freeblks *, int);
static	void handle_workitem_indirblk(struct freework *);
static	void handle_written_freework(struct freework *);
static	void merge_inode_lists(struct allocdirectlst *,struct allocdirectlst *);
static	struct worklist *jnewblk_merge(struct worklist *, struct worklist *,
	    struct workhead *);
static	struct freefrag *setup_allocindir_phase2(struct buf *, struct inode *,
	    struct inodedep *, struct allocindir *, ufs_lbn_t);
static	struct allocindir *newallocindir(struct inode *, int, ufs2_daddr_t,
	    ufs2_daddr_t, ufs_lbn_t);
static	void handle_workitem_freefrag(struct freefrag *);
static	struct freefrag *newfreefrag(struct inode *, ufs2_daddr_t, long,
	    ufs_lbn_t, u_long);
static	void allocdirect_merge(struct allocdirectlst *,
	    struct allocdirect *, struct allocdirect *);
static	struct freefrag *allocindir_merge(struct allocindir *,
	    struct allocindir *);
static	int bmsafemap_find(struct bmsafemap_hashhead *, int,
	    struct bmsafemap **);
static	struct bmsafemap *bmsafemap_lookup(struct mount *, struct buf *,
	    int cg, struct bmsafemap *);
static	int newblk_find(struct newblk_hashhead *, ufs2_daddr_t, int,
	    struct newblk **);
static	int newblk_lookup(struct mount *, ufs2_daddr_t, int, struct newblk **);
static	int inodedep_find(struct inodedep_hashhead *, ino_t,
	    struct inodedep **);
static	int inodedep_lookup(struct mount *, ino_t, int, struct inodedep **);
static	int pagedep_lookup(struct mount *, struct buf *bp, ino_t, ufs_lbn_t,
	    int, struct pagedep **);
static	int pagedep_find(struct pagedep_hashhead *, ino_t, ufs_lbn_t,
	    struct pagedep **);
static	void pause_timer(void *);
static	int request_cleanup(struct mount *, int);
static	int softdep_request_cleanup_flush(struct mount *, struct ufsmount *);
static	void schedule_cleanup(struct mount *);
static void softdep_ast_cleanup_proc(struct thread *);
static struct ufsmount *softdep_bp_to_mp(struct buf *bp);
static	int process_worklist_item(struct mount *, int, int);
static	void process_removes(struct vnode *);
static	void process_truncates(struct vnode *);
static	void jwork_move(struct workhead *, struct workhead *);
static	void jwork_insert(struct workhead *, struct jsegdep *);
static	void add_to_worklist(struct worklist *, int);
static	void wake_worklist(struct worklist *);
static	void wait_worklist(struct worklist *, char *);
static	void remove_from_worklist(struct worklist *);
static	void softdep_flush(void *);
static	void softdep_flushjournal(struct mount *);
static	int softdep_speedup(struct ufsmount *);
static	void worklist_speedup(struct mount *);
static	int journal_mount(struct mount *, struct fs *, struct ucred *);
static	void journal_unmount(struct ufsmount *);
static	int journal_space(struct ufsmount *, int);
static	void journal_suspend(struct ufsmount *);
static	int journal_unsuspend(struct ufsmount *ump);
static	void softdep_prelink(struct vnode *, struct vnode *);
static	void add_to_journal(struct worklist *);
static	void remove_from_journal(struct worklist *);
static	bool softdep_excess_items(struct ufsmount *, int);
static	void softdep_process_journal(struct mount *, struct worklist *, int);
static	struct jremref *newjremref(struct dirrem *, struct inode *,
	    struct inode *ip, off_t, nlink_t);
static	struct jaddref *newjaddref(struct inode *, ino_t, off_t, int16_t,
	    uint16_t);
static	inline void newinoref(struct inoref *, ino_t, ino_t, off_t, nlink_t,
	    uint16_t);
static	inline struct jsegdep *inoref_jseg(struct inoref *);
static	struct jmvref *newjmvref(struct inode *, ino_t, off_t, off_t);
static	struct jfreeblk *newjfreeblk(struct freeblks *, ufs_lbn_t,
	    ufs2_daddr_t, int);
static	void adjust_newfreework(struct freeblks *, int);
static	struct jtrunc *newjtrunc(struct freeblks *, off_t, int);
static	void move_newblock_dep(struct jaddref *, struct inodedep *);
static	void cancel_jfreeblk(struct freeblks *, ufs2_daddr_t);
static	struct jfreefrag *newjfreefrag(struct freefrag *, struct inode *,
	    ufs2_daddr_t, long, ufs_lbn_t);
static	struct freework *newfreework(struct ufsmount *, struct freeblks *,
	    struct freework *, ufs_lbn_t, ufs2_daddr_t, int, int, int);
static	int jwait(struct worklist *, int);
static	struct inodedep *inodedep_lookup_ip(struct inode *);
static	int bmsafemap_backgroundwrite(struct bmsafemap *, struct buf *);
static	struct freefile *handle_bufwait(struct inodedep *, struct workhead *);
static	void handle_jwork(struct workhead *);
static	struct mkdir *setup_newdir(struct diradd *, ino_t, ino_t, struct buf *,
	    struct mkdir **);
static	struct jblocks *jblocks_create(void);
static	ufs2_daddr_t jblocks_alloc(struct jblocks *, int, int *);
static	void jblocks_free(struct jblocks *, struct mount *, int);
static	void jblocks_destroy(struct jblocks *);
static	void jblocks_add(struct jblocks *, ufs2_daddr_t, int);

/*
 * Exported softdep operations.
 */
static	void softdep_disk_io_initiation(struct buf *);
static	void softdep_disk_write_complete(struct buf *);
static	void softdep_deallocate_dependencies(struct buf *);
static	int softdep_count_dependencies(struct buf *bp, int);

/*
 * Global lock over all of soft updates.
 */
static struct mtx lk;
MTX_SYSINIT(softdep_lock, &lk, "Global Softdep Lock", MTX_DEF);

#define ACQUIRE_GBLLOCK(lk)	mtx_lock(lk)
#define FREE_GBLLOCK(lk)	mtx_unlock(lk)
#define GBLLOCK_OWNED(lk)	mtx_assert((lk), MA_OWNED)

/*
 * Per-filesystem soft-updates locking.
 */
#define LOCK_PTR(ump)		(&(ump)->um_softdep->sd_fslock)
#define TRY_ACQUIRE_LOCK(ump)	rw_try_wlock(&(ump)->um_softdep->sd_fslock)
#define ACQUIRE_LOCK(ump)	rw_wlock(&(ump)->um_softdep->sd_fslock)
#define FREE_LOCK(ump)		rw_wunlock(&(ump)->um_softdep->sd_fslock)
#define LOCK_OWNED(ump)		rw_assert(&(ump)->um_softdep->sd_fslock, \
				    RA_WLOCKED)

#define	BUF_AREC(bp)		lockallowrecurse(&(bp)->b_lock)
#define	BUF_NOREC(bp)		lockdisablerecurse(&(bp)->b_lock)

/*
 * Worklist queue management.
 * These routines require that the lock be held.
 */
#ifndef /* NOT */ DEBUG
#define WORKLIST_INSERT(head, item) do {	\
	(item)->wk_state |= ONWORKLIST;		\
	LIST_INSERT_HEAD(head, item, wk_list);	\
} while (0)
#define WORKLIST_REMOVE(item) do {		\
	(item)->wk_state &= ~ONWORKLIST;	\
	LIST_REMOVE(item, wk_list);		\
} while (0)
#define WORKLIST_INSERT_UNLOCKED	WORKLIST_INSERT
#define WORKLIST_REMOVE_UNLOCKED	WORKLIST_REMOVE

#else /* DEBUG */
static	void worklist_insert(struct workhead *, struct worklist *, int);
static	void worklist_remove(struct worklist *, int);

#define WORKLIST_INSERT(head, item) worklist_insert(head, item, 1)
#define WORKLIST_INSERT_UNLOCKED(head, item) worklist_insert(head, item, 0)
#define WORKLIST_REMOVE(item) worklist_remove(item, 1)
#define WORKLIST_REMOVE_UNLOCKED(item) worklist_remove(item, 0)

static void
worklist_insert(head, item, locked)
	struct workhead *head;
	struct worklist *item;
	int locked;
{

	if (locked)
		LOCK_OWNED(VFSTOUFS(item->wk_mp));
	if (item->wk_state & ONWORKLIST)
		panic("worklist_insert: %p %s(0x%X) already on list",
		    item, TYPENAME(item->wk_type), item->wk_state);
	item->wk_state |= ONWORKLIST;
	LIST_INSERT_HEAD(head, item, wk_list);
}

static void
worklist_remove(item, locked)
	struct worklist *item;
	int locked;
{

	if (locked)
		LOCK_OWNED(VFSTOUFS(item->wk_mp));
	if ((item->wk_state & ONWORKLIST) == 0)
		panic("worklist_remove: %p %s(0x%X) not on list",
		    item, TYPENAME(item->wk_type), item->wk_state);
	item->wk_state &= ~ONWORKLIST;
	LIST_REMOVE(item, wk_list);
}
#endif /* DEBUG */

/*
 * Merge two jsegdeps keeping only the oldest one as newer references
 * can't be discarded until after older references.
 */
static inline struct jsegdep *
jsegdep_merge(struct jsegdep *one, struct jsegdep *two)
{
	struct jsegdep *swp;

	if (two == NULL)
		return (one);

	if (one->jd_seg->js_seq > two->jd_seg->js_seq) {
		swp = one;
		one = two;
		two = swp;
	}
	WORKLIST_REMOVE(&two->jd_list);
	free_jsegdep(two);

	return (one);
}

/*
 * If two freedeps are compatible free one to reduce list size.
 */
static inline struct freedep *
freedep_merge(struct freedep *one, struct freedep *two)
{
	if (two == NULL)
		return (one);

	if (one->fd_freework == two->fd_freework) {
		WORKLIST_REMOVE(&two->fd_list);
		free_freedep(two);
	}
	return (one);
}

/*
 * Move journal work from one list to another.  Duplicate freedeps and
 * jsegdeps are coalesced to keep the lists as small as possible.
 */
static void
jwork_move(dst, src)
	struct workhead *dst;
	struct workhead *src;
{
	struct freedep *freedep;
	struct jsegdep *jsegdep;
	struct worklist *wkn;
	struct worklist *wk;

	KASSERT(dst != src,
	    ("jwork_move: dst == src"));
	freedep = NULL;
	jsegdep = NULL;
	LIST_FOREACH_SAFE(wk, dst, wk_list, wkn) {
		if (wk->wk_type == D_JSEGDEP)
			jsegdep = jsegdep_merge(WK_JSEGDEP(wk), jsegdep);
		else if (wk->wk_type == D_FREEDEP)
			freedep = freedep_merge(WK_FREEDEP(wk), freedep);
	}

	while ((wk = LIST_FIRST(src)) != NULL) {
		WORKLIST_REMOVE(wk);
		WORKLIST_INSERT(dst, wk);
		if (wk->wk_type == D_JSEGDEP) {
			jsegdep = jsegdep_merge(WK_JSEGDEP(wk), jsegdep);
			continue;
		}
		if (wk->wk_type == D_FREEDEP)
			freedep = freedep_merge(WK_FREEDEP(wk), freedep);
	}
}

static void
jwork_insert(dst, jsegdep)
	struct workhead *dst;
	struct jsegdep *jsegdep;
{
	struct jsegdep *jsegdepn;
	struct worklist *wk;

	LIST_FOREACH(wk, dst, wk_list)
		if (wk->wk_type == D_JSEGDEP)
			break;
	if (wk == NULL) {
		WORKLIST_INSERT(dst, &jsegdep->jd_list);
		return;
	}
	jsegdepn = WK_JSEGDEP(wk);
	if (jsegdep->jd_seg->js_seq < jsegdepn->jd_seg->js_seq) {
		WORKLIST_REMOVE(wk);
		free_jsegdep(jsegdepn);
		WORKLIST_INSERT(dst, &jsegdep->jd_list);
	} else
		free_jsegdep(jsegdep);
}

/*
 * Routines for tracking and managing workitems.
 */
static	void workitem_free(struct worklist *, int);
static	void workitem_alloc(struct worklist *, int, struct mount *);
static	void workitem_reassign(struct worklist *, int);

#define	WORKITEM_FREE(item, type) \
	workitem_free((struct worklist *)(item), (type))
#define	WORKITEM_REASSIGN(item, type) \
	workitem_reassign((struct worklist *)(item), (type))

static void
workitem_free(item, type)
	struct worklist *item;
	int type;
{
	struct ufsmount *ump;

#ifdef DEBUG
	if (item->wk_state & ONWORKLIST)
		panic("workitem_free: %s(0x%X) still on list",
		    TYPENAME(item->wk_type), item->wk_state);
	if (item->wk_type != type && type != D_NEWBLK)
		panic("workitem_free: type mismatch %s != %s",
		    TYPENAME(item->wk_type), TYPENAME(type));
#endif
	if (item->wk_state & IOWAITING)
		wakeup(item);
	ump = VFSTOUFS(item->wk_mp);
	LOCK_OWNED(ump);
	KASSERT(ump->softdep_deps > 0,
	    ("workitem_free: %s: softdep_deps going negative",
	    ump->um_fs->fs_fsmnt));
	if (--ump->softdep_deps == 0 && ump->softdep_req)
		wakeup(&ump->softdep_deps);
	KASSERT(dep_current[item->wk_type] > 0,
	    ("workitem_free: %s: dep_current[%s] going negative",
	    ump->um_fs->fs_fsmnt, TYPENAME(item->wk_type)));
	KASSERT(ump->softdep_curdeps[item->wk_type] > 0,
	    ("workitem_free: %s: softdep_curdeps[%s] going negative",
	    ump->um_fs->fs_fsmnt, TYPENAME(item->wk_type)));
	atomic_subtract_long(&dep_current[item->wk_type], 1);
	ump->softdep_curdeps[item->wk_type] -= 1;
	free(item, DtoM(type));
}

static void
workitem_alloc(item, type, mp)
	struct worklist *item;
	int type;
	struct mount *mp;
{
	struct ufsmount *ump;

	item->wk_type = type;
	item->wk_mp = mp;
	item->wk_state = 0;

	ump = VFSTOUFS(mp);
	ACQUIRE_GBLLOCK(&lk);
	dep_current[type]++;
	if (dep_current[type] > dep_highuse[type])
		dep_highuse[type] = dep_current[type];
	dep_total[type]++;
	FREE_GBLLOCK(&lk);
	ACQUIRE_LOCK(ump);
	ump->softdep_curdeps[type] += 1;
	ump->softdep_deps++;
	ump->softdep_accdeps++;
	FREE_LOCK(ump);
}

static void
workitem_reassign(item, newtype)
	struct worklist *item;
	int newtype;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(item->wk_mp);
	LOCK_OWNED(ump);
	KASSERT(ump->softdep_curdeps[item->wk_type] > 0,
	    ("workitem_reassign: %s: softdep_curdeps[%s] going negative",
	    VFSTOUFS(item->wk_mp)->um_fs->fs_fsmnt, TYPENAME(item->wk_type)));
	ump->softdep_curdeps[item->wk_type] -= 1;
	ump->softdep_curdeps[newtype] += 1;
	KASSERT(dep_current[item->wk_type] > 0,
	    ("workitem_reassign: %s: dep_current[%s] going negative",
	    VFSTOUFS(item->wk_mp)->um_fs->fs_fsmnt, TYPENAME(item->wk_type)));
	ACQUIRE_GBLLOCK(&lk);
	dep_current[newtype]++;
	dep_current[item->wk_type]--;
	if (dep_current[newtype] > dep_highuse[newtype])
		dep_highuse[newtype] = dep_current[newtype];
	dep_total[newtype]++;
	FREE_GBLLOCK(&lk);
	item->wk_type = newtype;
}

/*
 * Workitem queue management
 */
static int max_softdeps;	/* maximum number of structs before slowdown */
static int tickdelay = 2;	/* number of ticks to pause during slowdown */
static int proc_waiting;	/* tracks whether we have a timeout posted */
static int *stat_countp;	/* statistic to count in proc_waiting timeout */
static struct callout softdep_callout;
static int req_clear_inodedeps;	/* syncer process flush some inodedeps */
static int req_clear_remove;	/* syncer process flush some freeblks */
static int softdep_flushcache = 0; /* Should we do BIO_FLUSH? */

/*
 * runtime statistics
 */
static int stat_flush_threads;	/* number of softdep flushing threads */
static int stat_worklist_push;	/* number of worklist cleanups */
static int stat_blk_limit_push;	/* number of times block limit neared */
static int stat_ino_limit_push;	/* number of times inode limit neared */
static int stat_blk_limit_hit;	/* number of times block slowdown imposed */
static int stat_ino_limit_hit;	/* number of times inode slowdown imposed */
static int stat_sync_limit_hit;	/* number of synchronous slowdowns imposed */
static int stat_indir_blk_ptrs;	/* bufs redirtied as indir ptrs not written */
static int stat_inode_bitmap;	/* bufs redirtied as inode bitmap not written */
static int stat_direct_blk_ptrs;/* bufs redirtied as direct ptrs not written */
static int stat_dir_entry;	/* bufs redirtied as dir entry cannot write */
static int stat_jaddref;	/* bufs redirtied as ino bitmap can not write */
static int stat_jnewblk;	/* bufs redirtied as blk bitmap can not write */
static int stat_journal_min;	/* Times hit journal min threshold */
static int stat_journal_low;	/* Times hit journal low threshold */
static int stat_journal_wait;	/* Times blocked in jwait(). */
static int stat_jwait_filepage;	/* Times blocked in jwait() for filepage. */
static int stat_jwait_freeblks;	/* Times blocked in jwait() for freeblks. */
static int stat_jwait_inode;	/* Times blocked in jwait() for inodes. */
static int stat_jwait_newblk;	/* Times blocked in jwait() for newblks. */
static int stat_cleanup_high_delay; /* Maximum cleanup delay (in ticks) */
static int stat_cleanup_blkrequests; /* Number of block cleanup requests */
static int stat_cleanup_inorequests; /* Number of inode cleanup requests */
static int stat_cleanup_retries; /* Number of cleanups that needed to flush */
static int stat_cleanup_failures; /* Number of cleanup requests that failed */
static int stat_emptyjblocks; /* Number of potentially empty journal blocks */

SYSCTL_INT(_debug_softdep, OID_AUTO, max_softdeps, CTLFLAG_RW,
    &max_softdeps, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, tickdelay, CTLFLAG_RW,
    &tickdelay, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, flush_threads, CTLFLAG_RD,
    &stat_flush_threads, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, worklist_push, CTLFLAG_RW,
    &stat_worklist_push, 0,"");
SYSCTL_INT(_debug_softdep, OID_AUTO, blk_limit_push, CTLFLAG_RW,
    &stat_blk_limit_push, 0,"");
SYSCTL_INT(_debug_softdep, OID_AUTO, ino_limit_push, CTLFLAG_RW,
    &stat_ino_limit_push, 0,"");
SYSCTL_INT(_debug_softdep, OID_AUTO, blk_limit_hit, CTLFLAG_RW,
    &stat_blk_limit_hit, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, ino_limit_hit, CTLFLAG_RW,
    &stat_ino_limit_hit, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, sync_limit_hit, CTLFLAG_RW,
    &stat_sync_limit_hit, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, indir_blk_ptrs, CTLFLAG_RW,
    &stat_indir_blk_ptrs, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, inode_bitmap, CTLFLAG_RW,
    &stat_inode_bitmap, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, direct_blk_ptrs, CTLFLAG_RW,
    &stat_direct_blk_ptrs, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, dir_entry, CTLFLAG_RW,
    &stat_dir_entry, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, jaddref_rollback, CTLFLAG_RW,
    &stat_jaddref, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, jnewblk_rollback, CTLFLAG_RW,
    &stat_jnewblk, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, journal_low, CTLFLAG_RW,
    &stat_journal_low, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, journal_min, CTLFLAG_RW,
    &stat_journal_min, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, journal_wait, CTLFLAG_RW,
    &stat_journal_wait, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, jwait_filepage, CTLFLAG_RW,
    &stat_jwait_filepage, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, jwait_freeblks, CTLFLAG_RW,
    &stat_jwait_freeblks, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, jwait_inode, CTLFLAG_RW,
    &stat_jwait_inode, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, jwait_newblk, CTLFLAG_RW,
    &stat_jwait_newblk, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, cleanup_blkrequests, CTLFLAG_RW,
    &stat_cleanup_blkrequests, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, cleanup_inorequests, CTLFLAG_RW,
    &stat_cleanup_inorequests, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, cleanup_high_delay, CTLFLAG_RW,
    &stat_cleanup_high_delay, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, cleanup_retries, CTLFLAG_RW,
    &stat_cleanup_retries, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, cleanup_failures, CTLFLAG_RW,
    &stat_cleanup_failures, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, flushcache, CTLFLAG_RW,
    &softdep_flushcache, 0, "");
SYSCTL_INT(_debug_softdep, OID_AUTO, emptyjblocks, CTLFLAG_RD,
    &stat_emptyjblocks, 0, "");

SYSCTL_DECL(_vfs_ffs);

/* Whether to recompute the summary at mount time */
static int compute_summary_at_mount = 0;
SYSCTL_INT(_vfs_ffs, OID_AUTO, compute_summary_at_mount, CTLFLAG_RW,
	   &compute_summary_at_mount, 0, "Recompute summary at mount");
static int print_threads = 0;
SYSCTL_INT(_debug_softdep, OID_AUTO, print_threads, CTLFLAG_RW,
    &print_threads, 0, "Notify flusher thread start/stop");

/* List of all filesystems mounted with soft updates */
static TAILQ_HEAD(, mount_softdeps) softdepmounts;

/*
 * This function cleans the worklist for a filesystem.
 * Each filesystem running with soft dependencies gets its own
 * thread to run in this function. The thread is started up in
 * softdep_mount and shutdown in softdep_unmount. They show up
 * as part of the kernel "bufdaemon" process whose process
 * entry is available in bufdaemonproc.
 */
static int searchfailed;
extern struct proc *bufdaemonproc;
static void
softdep_flush(addr)
	void *addr;
{
	struct mount *mp;
	struct thread *td;
	struct ufsmount *ump;

	td = curthread;
	td->td_pflags |= TDP_NORUNNINGBUF;
	mp = (struct mount *)addr;
	ump = VFSTOUFS(mp);
	atomic_add_int(&stat_flush_threads, 1);
	ACQUIRE_LOCK(ump);
	ump->softdep_flags &= ~FLUSH_STARTING;
	wakeup(&ump->softdep_flushtd);
	FREE_LOCK(ump);
	if (print_threads) {
		if (stat_flush_threads == 1)
			printf("Running %s at pid %d\n", bufdaemonproc->p_comm,
			    bufdaemonproc->p_pid);
		printf("Start thread %s\n", td->td_name);
	}
	for (;;) {	
		while (softdep_process_worklist(mp, 0) > 0 ||
		    (MOUNTEDSUJ(mp) &&
		    VFSTOUFS(mp)->softdep_jblocks->jb_suspended))
			kthread_suspend_check();
		ACQUIRE_LOCK(ump);
		if ((ump->softdep_flags & (FLUSH_CLEANUP | FLUSH_EXIT)) == 0)
			msleep(&ump->softdep_flushtd, LOCK_PTR(ump), PVM,
			    "sdflush", hz / 2);
		ump->softdep_flags &= ~FLUSH_CLEANUP;
		/*
		 * Check to see if we are done and need to exit.
		 */
		if ((ump->softdep_flags & FLUSH_EXIT) == 0) {
			FREE_LOCK(ump);
			continue;
		}
		ump->softdep_flags &= ~FLUSH_EXIT;
		FREE_LOCK(ump);
		wakeup(&ump->softdep_flags);
		if (print_threads)
			printf("Stop thread %s: searchfailed %d, did cleanups %d\n", td->td_name, searchfailed, ump->um_softdep->sd_cleanups);
		atomic_subtract_int(&stat_flush_threads, 1);
		kthread_exit();
		panic("kthread_exit failed\n");
	}
}

static void
worklist_speedup(mp)
	struct mount *mp;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(mp);
	LOCK_OWNED(ump);
	if ((ump->softdep_flags & (FLUSH_CLEANUP | FLUSH_EXIT)) == 0)
		ump->softdep_flags |= FLUSH_CLEANUP;
	wakeup(&ump->softdep_flushtd);
}

static int
softdep_speedup(ump)
	struct ufsmount *ump;
{
	struct ufsmount *altump;
	struct mount_softdeps *sdp;

	LOCK_OWNED(ump);
	worklist_speedup(ump->um_mountp);
	bd_speedup();
	/*
	 * If we have global shortages, then we need other
	 * filesystems to help with the cleanup. Here we wakeup a
	 * flusher thread for a filesystem that is over its fair
	 * share of resources.
	 */
	if (req_clear_inodedeps || req_clear_remove) {
		ACQUIRE_GBLLOCK(&lk);
		TAILQ_FOREACH(sdp, &softdepmounts, sd_next) {
			if ((altump = sdp->sd_ump) == ump)
				continue;
			if (((req_clear_inodedeps &&
			    altump->softdep_curdeps[D_INODEDEP] >
			    max_softdeps / stat_flush_threads) ||
			    (req_clear_remove &&
			    altump->softdep_curdeps[D_DIRREM] >
			    (max_softdeps / 2) / stat_flush_threads)) &&
			    TRY_ACQUIRE_LOCK(altump))
				break;
		}
		if (sdp == NULL) {
			searchfailed++;
			FREE_GBLLOCK(&lk);
		} else {
			/*
			 * Move to the end of the list so we pick a
			 * different one on out next try.
			 */
			TAILQ_REMOVE(&softdepmounts, sdp, sd_next);
			TAILQ_INSERT_TAIL(&softdepmounts, sdp, sd_next);
			FREE_GBLLOCK(&lk);
			if ((altump->softdep_flags &
			    (FLUSH_CLEANUP | FLUSH_EXIT)) == 0)
				altump->softdep_flags |= FLUSH_CLEANUP;
			altump->um_softdep->sd_cleanups++;
			wakeup(&altump->softdep_flushtd);
			FREE_LOCK(altump);
		}
	}
	return (speedup_syncer());
}

/*
 * Add an item to the end of the work queue.
 * This routine requires that the lock be held.
 * This is the only routine that adds items to the list.
 * The following routine is the only one that removes items
 * and does so in order from first to last.
 */

#define	WK_HEAD		0x0001	/* Add to HEAD. */
#define	WK_NODELAY	0x0002	/* Process immediately. */

static void
add_to_worklist(wk, flags)
	struct worklist *wk;
	int flags;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(wk->wk_mp);
	LOCK_OWNED(ump);
	if (wk->wk_state & ONWORKLIST)
		panic("add_to_worklist: %s(0x%X) already on list",
		    TYPENAME(wk->wk_type), wk->wk_state);
	wk->wk_state |= ONWORKLIST;
	if (ump->softdep_on_worklist == 0) {
		LIST_INSERT_HEAD(&ump->softdep_workitem_pending, wk, wk_list);
		ump->softdep_worklist_tail = wk;
	} else if (flags & WK_HEAD) {
		LIST_INSERT_HEAD(&ump->softdep_workitem_pending, wk, wk_list);
	} else {
		LIST_INSERT_AFTER(ump->softdep_worklist_tail, wk, wk_list);
		ump->softdep_worklist_tail = wk;
	}
	ump->softdep_on_worklist += 1;
	if (flags & WK_NODELAY)
		worklist_speedup(wk->wk_mp);
}

/*
 * Remove the item to be processed. If we are removing the last
 * item on the list, we need to recalculate the tail pointer.
 */
static void
remove_from_worklist(wk)
	struct worklist *wk;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(wk->wk_mp);
	if (ump->softdep_worklist_tail == wk)
		ump->softdep_worklist_tail =
		    (struct worklist *)wk->wk_list.le_prev;
	WORKLIST_REMOVE(wk);
	ump->softdep_on_worklist -= 1;
}

static void
wake_worklist(wk)
	struct worklist *wk;
{
	if (wk->wk_state & IOWAITING) {
		wk->wk_state &= ~IOWAITING;
		wakeup(wk);
	}
}

static void
wait_worklist(wk, wmesg)
	struct worklist *wk;
	char *wmesg;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(wk->wk_mp);
	wk->wk_state |= IOWAITING;
	msleep(wk, LOCK_PTR(ump), PVM, wmesg, 0);
}

/*
 * Process that runs once per second to handle items in the background queue.
 *
 * Note that we ensure that everything is done in the order in which they
 * appear in the queue. The code below depends on this property to ensure
 * that blocks of a file are freed before the inode itself is freed. This
 * ordering ensures that no new <vfsid, inum, lbn> triples will be generated
 * until all the old ones have been purged from the dependency lists.
 */
static int 
softdep_process_worklist(mp, full)
	struct mount *mp;
	int full;
{
	int cnt, matchcnt;
	struct ufsmount *ump;
	long starttime;

	KASSERT(mp != NULL, ("softdep_process_worklist: NULL mp"));
	if (MOUNTEDSOFTDEP(mp) == 0)
		return (0);
	matchcnt = 0;
	ump = VFSTOUFS(mp);
	ACQUIRE_LOCK(ump);
	starttime = time_second;
	softdep_process_journal(mp, NULL, full ? MNT_WAIT : 0);
	check_clear_deps(mp);
	while (ump->softdep_on_worklist > 0) {
		if ((cnt = process_worklist_item(mp, 10, LK_NOWAIT)) == 0)
			break;
		else
			matchcnt += cnt;
		check_clear_deps(mp);
		/*
		 * We do not generally want to stop for buffer space, but if
		 * we are really being a buffer hog, we will stop and wait.
		 */
		if (should_yield()) {
			FREE_LOCK(ump);
			kern_yield(PRI_USER);
			bwillwrite();
			ACQUIRE_LOCK(ump);
		}
		/*
		 * Never allow processing to run for more than one
		 * second. This gives the syncer thread the opportunity
		 * to pause if appropriate.
		 */
		if (!full && starttime != time_second)
			break;
	}
	if (full == 0)
		journal_unsuspend(ump);
	FREE_LOCK(ump);
	return (matchcnt);
}

/*
 * Process all removes associated with a vnode if we are running out of
 * journal space.  Any other process which attempts to flush these will
 * be unable as we have the vnodes locked.
 */
static void
process_removes(vp)
	struct vnode *vp;
{
	struct inodedep *inodedep;
	struct dirrem *dirrem;
	struct ufsmount *ump;
	struct mount *mp;
	ino_t inum;

	mp = vp->v_mount;
	ump = VFSTOUFS(mp);
	LOCK_OWNED(ump);
	inum = VTOI(vp)->i_number;
	for (;;) {
top:
		if (inodedep_lookup(mp, inum, 0, &inodedep) == 0)
			return;
		LIST_FOREACH(dirrem, &inodedep->id_dirremhd, dm_inonext) {
			/*
			 * If another thread is trying to lock this vnode
			 * it will fail but we must wait for it to do so
			 * before we can proceed.
			 */
			if (dirrem->dm_state & INPROGRESS) {
				wait_worklist(&dirrem->dm_list, "pwrwait");
				goto top;
			}
			if ((dirrem->dm_state & (COMPLETE | ONWORKLIST)) == 
			    (COMPLETE | ONWORKLIST))
				break;
		}
		if (dirrem == NULL)
			return;
		remove_from_worklist(&dirrem->dm_list);
		FREE_LOCK(ump);
		if (vn_start_secondary_write(NULL, &mp, V_NOWAIT))
			panic("process_removes: suspended filesystem");
		handle_workitem_remove(dirrem, 0);
		vn_finished_secondary_write(mp);
		ACQUIRE_LOCK(ump);
	}
}

/*
 * Process all truncations associated with a vnode if we are running out
 * of journal space.  This is called when the vnode lock is already held
 * and no other process can clear the truncation.  This function returns
 * a value greater than zero if it did any work.
 */
static void
process_truncates(vp)
	struct vnode *vp;
{
	struct inodedep *inodedep;
	struct freeblks *freeblks;
	struct ufsmount *ump;
	struct mount *mp;
	ino_t inum;
	int cgwait;

	mp = vp->v_mount;
	ump = VFSTOUFS(mp);
	LOCK_OWNED(ump);
	inum = VTOI(vp)->i_number;
	for (;;) {
		if (inodedep_lookup(mp, inum, 0, &inodedep) == 0)
			return;
		cgwait = 0;
		TAILQ_FOREACH(freeblks, &inodedep->id_freeblklst, fb_next) {
			/* Journal entries not yet written.  */
			if (!LIST_EMPTY(&freeblks->fb_jblkdephd)) {
				jwait(&LIST_FIRST(
				    &freeblks->fb_jblkdephd)->jb_list,
				    MNT_WAIT);
				break;
			}
			/* Another thread is executing this item. */
			if (freeblks->fb_state & INPROGRESS) {
				wait_worklist(&freeblks->fb_list, "ptrwait");
				break;
			}
			/* Freeblks is waiting on a inode write. */
			if ((freeblks->fb_state & COMPLETE) == 0) {
				FREE_LOCK(ump);
				ffs_update(vp, 1);
				ACQUIRE_LOCK(ump);
				break;
			}
			if ((freeblks->fb_state & (ALLCOMPLETE | ONWORKLIST)) ==
			    (ALLCOMPLETE | ONWORKLIST)) {
				remove_from_worklist(&freeblks->fb_list);
				freeblks->fb_state |= INPROGRESS;
				FREE_LOCK(ump);
				if (vn_start_secondary_write(NULL, &mp,
				    V_NOWAIT))
					panic("process_truncates: "
					    "suspended filesystem");
				handle_workitem_freeblocks(freeblks, 0);
				vn_finished_secondary_write(mp);
				ACQUIRE_LOCK(ump);
				break;
			}
			if (freeblks->fb_cgwait)
				cgwait++;
		}
		if (cgwait) {
			FREE_LOCK(ump);
			sync_cgs(mp, MNT_WAIT);
			ffs_sync_snap(mp, MNT_WAIT);
			ACQUIRE_LOCK(ump);
			continue;
		}
		if (freeblks == NULL)
			break;
	}
	return;
}

/*
 * Process one item on the worklist.
 */
static int
process_worklist_item(mp, target, flags)
	struct mount *mp;
	int target;
	int flags;
{
	struct worklist sentinel;
	struct worklist *wk;
	struct ufsmount *ump;
	int matchcnt;
	int error;

	KASSERT(mp != NULL, ("process_worklist_item: NULL mp"));
	/*
	 * If we are being called because of a process doing a
	 * copy-on-write, then it is not safe to write as we may
	 * recurse into the copy-on-write routine.
	 */
	if (curthread->td_pflags & TDP_COWINPROGRESS)
		return (-1);
	PHOLD(curproc);	/* Don't let the stack go away. */
	ump = VFSTOUFS(mp);
	LOCK_OWNED(ump);
	matchcnt = 0;
	sentinel.wk_mp = NULL;
	sentinel.wk_type = D_SENTINEL;
	LIST_INSERT_HEAD(&ump->softdep_workitem_pending, &sentinel, wk_list);
	for (wk = LIST_NEXT(&sentinel, wk_list); wk != NULL;
	    wk = LIST_NEXT(&sentinel, wk_list)) {
		if (wk->wk_type == D_SENTINEL) {
			LIST_REMOVE(&sentinel, wk_list);
			LIST_INSERT_AFTER(wk, &sentinel, wk_list);
			continue;
		}
		if (wk->wk_state & INPROGRESS)
			panic("process_worklist_item: %p already in progress.",
			    wk);
		wk->wk_state |= INPROGRESS;
		remove_from_worklist(wk);
		FREE_LOCK(ump);
		if (vn_start_secondary_write(NULL, &mp, V_NOWAIT))
			panic("process_worklist_item: suspended filesystem");
		switch (wk->wk_type) {
		case D_DIRREM:
			/* removal of a directory entry */
			error = handle_workitem_remove(WK_DIRREM(wk), flags);
			break;

		case D_FREEBLKS:
			/* releasing blocks and/or fragments from a file */
			error = handle_workitem_freeblocks(WK_FREEBLKS(wk),
			    flags);
			break;

		case D_FREEFRAG:
			/* releasing a fragment when replaced as a file grows */
			handle_workitem_freefrag(WK_FREEFRAG(wk));
			error = 0;
			break;

		case D_FREEFILE:
			/* releasing an inode when its link count drops to 0 */
			handle_workitem_freefile(WK_FREEFILE(wk));
			error = 0;
			break;

		default:
			panic("%s_process_worklist: Unknown type %s",
			    "softdep", TYPENAME(wk->wk_type));
			/* NOTREACHED */
		}
		vn_finished_secondary_write(mp);
		ACQUIRE_LOCK(ump);
		if (error == 0) {
			if (++matchcnt == target)
				break;
			continue;
		}
		/*
		 * We have to retry the worklist item later.  Wake up any
		 * waiters who may be able to complete it immediately and
		 * add the item back to the head so we don't try to execute
		 * it again.
		 */
		wk->wk_state &= ~INPROGRESS;
		wake_worklist(wk);
		add_to_worklist(wk, WK_HEAD);
	}
	/* Sentinal could've become the tail from remove_from_worklist. */
	if (ump->softdep_worklist_tail == &sentinel)
		ump->softdep_worklist_tail =
		    (struct worklist *)sentinel.wk_list.le_prev;
	LIST_REMOVE(&sentinel, wk_list);
	PRELE(curproc);
	return (matchcnt);
}

/*
 * Move dependencies from one buffer to another.
 */
int
softdep_move_dependencies(oldbp, newbp)
	struct buf *oldbp;
	struct buf *newbp;
{
	struct worklist *wk, *wktail;
	struct ufsmount *ump;
	int dirty;

	if ((wk = LIST_FIRST(&oldbp->b_dep)) == NULL)
		return (0);
	KASSERT(MOUNTEDSOFTDEP(wk->wk_mp) != 0,
	    ("softdep_move_dependencies called on non-softdep filesystem"));
	dirty = 0;
	wktail = NULL;
	ump = VFSTOUFS(wk->wk_mp);
	ACQUIRE_LOCK(ump);
	while ((wk = LIST_FIRST(&oldbp->b_dep)) != NULL) {
		LIST_REMOVE(wk, wk_list);
		if (wk->wk_type == D_BMSAFEMAP &&
		    bmsafemap_backgroundwrite(WK_BMSAFEMAP(wk), newbp))
			dirty = 1;
		if (wktail == NULL)
			LIST_INSERT_HEAD(&newbp->b_dep, wk, wk_list);
		else
			LIST_INSERT_AFTER(wktail, wk, wk_list);
		wktail = wk;
	}
	FREE_LOCK(ump);

	return (dirty);
}

/*
 * Purge the work list of all items associated with a particular mount point.
 */
int
softdep_flushworklist(oldmnt, countp, td)
	struct mount *oldmnt;
	int *countp;
	struct thread *td;
{
	struct vnode *devvp;
	struct ufsmount *ump;
	int count, error;

	/*
	 * Alternately flush the block device associated with the mount
	 * point and process any dependencies that the flushing
	 * creates. We continue until no more worklist dependencies
	 * are found.
	 */
	*countp = 0;
	error = 0;
	ump = VFSTOUFS(oldmnt);
	devvp = ump->um_devvp;
	while ((count = softdep_process_worklist(oldmnt, 1)) > 0) {
		*countp += count;
		vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
		error = VOP_FSYNC(devvp, MNT_WAIT, td);
		VOP_UNLOCK(devvp, 0);
		if (error != 0)
			break;
	}
	return (error);
}

#define	SU_WAITIDLE_RETRIES	20
static int
softdep_waitidle(struct mount *mp, int flags __unused)
{
	struct ufsmount *ump;
	struct vnode *devvp;
	struct thread *td;
	int error, i;

	ump = VFSTOUFS(mp);
	devvp = ump->um_devvp;
	td = curthread;
	error = 0;
	ACQUIRE_LOCK(ump);
	for (i = 0; i < SU_WAITIDLE_RETRIES && ump->softdep_deps != 0; i++) {
		ump->softdep_req = 1;
		KASSERT((flags & FORCECLOSE) == 0 ||
		    ump->softdep_on_worklist == 0,
		    ("softdep_waitidle: work added after flush"));
		msleep(&ump->softdep_deps, LOCK_PTR(ump), PVM | PDROP,
		    "softdeps", 10 * hz);
		vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
		error = VOP_FSYNC(devvp, MNT_WAIT, td);
		VOP_UNLOCK(devvp, 0);
		ACQUIRE_LOCK(ump);
		if (error != 0)
			break;
	}
	ump->softdep_req = 0;
	if (i == SU_WAITIDLE_RETRIES && error == 0 && ump->softdep_deps != 0) {
		error = EBUSY;
		printf("softdep_waitidle: Failed to flush worklist for %p\n",
		    mp);
	}
	FREE_LOCK(ump);
	return (error);
}

/*
 * Flush all vnodes and worklist items associated with a specified mount point.
 */
int
softdep_flushfiles(oldmnt, flags, td)
	struct mount *oldmnt;
	int flags;
	struct thread *td;
{
#ifdef QUOTA
	struct ufsmount *ump;
	int i;
#endif
	int error, early, depcount, loopcnt, retry_flush_count, retry;
	int morework;

	KASSERT(MOUNTEDSOFTDEP(oldmnt) != 0,
	    ("softdep_flushfiles called on non-softdep filesystem"));
	loopcnt = 10;
	retry_flush_count = 3;
retry_flush:
	error = 0;

	/*
	 * Alternately flush the vnodes associated with the mount
	 * point and process any dependencies that the flushing
	 * creates. In theory, this loop can happen at most twice,
	 * but we give it a few extra just to be sure.
	 */
	for (; loopcnt > 0; loopcnt--) {
		/*
		 * Do another flush in case any vnodes were brought in
		 * as part of the cleanup operations.
		 */
		early = retry_flush_count == 1 || (oldmnt->mnt_kern_flag &
		    MNTK_UNMOUNT) == 0 ? 0 : EARLYFLUSH;
		if ((error = ffs_flushfiles(oldmnt, flags | early, td)) != 0)
			break;
		if ((error = softdep_flushworklist(oldmnt, &depcount, td)) != 0 ||
		    depcount == 0)
			break;
	}
	/*
	 * If we are unmounting then it is an error to fail. If we
	 * are simply trying to downgrade to read-only, then filesystem
	 * activity can keep us busy forever, so we just fail with EBUSY.
	 */
	if (loopcnt == 0) {
		if (oldmnt->mnt_kern_flag & MNTK_UNMOUNT)
			panic("softdep_flushfiles: looping");
		error = EBUSY;
	}
	if (!error)
		error = softdep_waitidle(oldmnt, flags);
	if (!error) {
		if (oldmnt->mnt_kern_flag & MNTK_UNMOUNT) {
			retry = 0;
			MNT_ILOCK(oldmnt);
			KASSERT((oldmnt->mnt_kern_flag & MNTK_NOINSMNTQ) != 0,
			    ("softdep_flushfiles: !MNTK_NOINSMNTQ"));
			morework = oldmnt->mnt_nvnodelistsize > 0;
#ifdef QUOTA
			ump = VFSTOUFS(oldmnt);
			UFS_LOCK(ump);
			for (i = 0; i < MAXQUOTAS; i++) {
				if (ump->um_quotas[i] != NULLVP)
					morework = 1;
			}
			UFS_UNLOCK(ump);
#endif
			if (morework) {
				if (--retry_flush_count > 0) {
					retry = 1;
					loopcnt = 3;
				} else
					error = EBUSY;
			}
			MNT_IUNLOCK(oldmnt);
			if (retry)
				goto retry_flush;
		}
	}
	return (error);
}

/*
 * Structure hashing.
 * 
 * There are four types of structures that can be looked up:
 *	1) pagedep structures identified by mount point, inode number,
 *	   and logical block.
 *	2) inodedep structures identified by mount point and inode number.
 *	3) newblk structures identified by mount point and
 *	   physical block number.
 *	4) bmsafemap structures identified by mount point and
 *	   cylinder group number.
 *
 * The "pagedep" and "inodedep" dependency structures are hashed
 * separately from the file blocks and inodes to which they correspond.
 * This separation helps when the in-memory copy of an inode or
 * file block must be replaced. It also obviates the need to access
 * an inode or file page when simply updating (or de-allocating)
 * dependency structures. Lookup of newblk structures is needed to
 * find newly allocated blocks when trying to associate them with
 * their allocdirect or allocindir structure.
 *
 * The lookup routines optionally create and hash a new instance when
 * an existing entry is not found. The bmsafemap lookup routine always
 * allocates a new structure if an existing one is not found.
 */
#define DEPALLOC	0x0001	/* allocate structure if lookup fails */

/*
 * Structures and routines associated with pagedep caching.
 */
#define	PAGEDEP_HASH(ump, inum, lbn) \
	(&(ump)->pagedep_hashtbl[((inum) + (lbn)) & (ump)->pagedep_hash_size])

static int
pagedep_find(pagedephd, ino, lbn, pagedeppp)
	struct pagedep_hashhead *pagedephd;
	ino_t ino;
	ufs_lbn_t lbn;
	struct pagedep **pagedeppp;
{
	struct pagedep *pagedep;

	LIST_FOREACH(pagedep, pagedephd, pd_hash) {
		if (ino == pagedep->pd_ino && lbn == pagedep->pd_lbn) {
			*pagedeppp = pagedep;
			return (1);
		}
	}
	*pagedeppp = NULL;
	return (0);
}
/*
 * Look up a pagedep. Return 1 if found, 0 otherwise.
 * If not found, allocate if DEPALLOC flag is passed.
 * Found or allocated entry is returned in pagedeppp.
 * This routine must be called with splbio interrupts blocked.
 */
static int
pagedep_lookup(mp, bp, ino, lbn, flags, pagedeppp)
	struct mount *mp;
	struct buf *bp;
	ino_t ino;
	ufs_lbn_t lbn;
	int flags;
	struct pagedep **pagedeppp;
{
	struct pagedep *pagedep;
	struct pagedep_hashhead *pagedephd;
	struct worklist *wk;
	struct ufsmount *ump;
	int ret;
	int i;

	ump = VFSTOUFS(mp);
	LOCK_OWNED(ump);
	if (bp) {
		LIST_FOREACH(wk, &bp->b_dep, wk_list) {
			if (wk->wk_type == D_PAGEDEP) {
				*pagedeppp = WK_PAGEDEP(wk);
				return (1);
			}
		}
	}
	pagedephd = PAGEDEP_HASH(ump, ino, lbn);
	ret = pagedep_find(pagedephd, ino, lbn, pagedeppp);
	if (ret) {
		if (((*pagedeppp)->pd_state & ONWORKLIST) == 0 && bp)
			WORKLIST_INSERT(&bp->b_dep, &(*pagedeppp)->pd_list);
		return (1);
	}
	if ((flags & DEPALLOC) == 0)
		return (0);
	FREE_LOCK(ump);
	pagedep = malloc(sizeof(struct pagedep),
	    M_PAGEDEP, M_SOFTDEP_FLAGS|M_ZERO);
	workitem_alloc(&pagedep->pd_list, D_PAGEDEP, mp);
	ACQUIRE_LOCK(ump);
	ret = pagedep_find(pagedephd, ino, lbn, pagedeppp);
	if (*pagedeppp) {
		/*
		 * This should never happen since we only create pagedeps
		 * with the vnode lock held.  Could be an assert.
		 */
		WORKITEM_FREE(pagedep, D_PAGEDEP);
		return (ret);
	}
	pagedep->pd_ino = ino;
	pagedep->pd_lbn = lbn;
	LIST_INIT(&pagedep->pd_dirremhd);
	LIST_INIT(&pagedep->pd_pendinghd);
	for (i = 0; i < DAHASHSZ; i++)
		LIST_INIT(&pagedep->pd_diraddhd[i]);
	LIST_INSERT_HEAD(pagedephd, pagedep, pd_hash);
	WORKLIST_INSERT(&bp->b_dep, &pagedep->pd_list);
	*pagedeppp = pagedep;
	return (0);
}

/*
 * Structures and routines associated with inodedep caching.
 */
#define	INODEDEP_HASH(ump, inum) \
      (&(ump)->inodedep_hashtbl[(inum) & (ump)->inodedep_hash_size])

static int
inodedep_find(inodedephd, inum, inodedeppp)
	struct inodedep_hashhead *inodedephd;
	ino_t inum;
	struct inodedep **inodedeppp;
{
	struct inodedep *inodedep;

	LIST_FOREACH(inodedep, inodedephd, id_hash)
		if (inum == inodedep->id_ino)
			break;
	if (inodedep) {
		*inodedeppp = inodedep;
		return (1);
	}
	*inodedeppp = NULL;

	return (0);
}
/*
 * Look up an inodedep. Return 1 if found, 0 if not found.
 * If not found, allocate if DEPALLOC flag is passed.
 * Found or allocated entry is returned in inodedeppp.
 * This routine must be called with splbio interrupts blocked.
 */
static int
inodedep_lookup(mp, inum, flags, inodedeppp)
	struct mount *mp;
	ino_t inum;
	int flags;
	struct inodedep **inodedeppp;
{
	struct inodedep *inodedep;
	struct inodedep_hashhead *inodedephd;
	struct ufsmount *ump;
	struct fs *fs;

	ump = VFSTOUFS(mp);
	LOCK_OWNED(ump);
	fs = ump->um_fs;
	inodedephd = INODEDEP_HASH(ump, inum);

	if (inodedep_find(inodedephd, inum, inodedeppp))
		return (1);
	if ((flags & DEPALLOC) == 0)
		return (0);
	/*
	 * If the system is over its limit and our filesystem is
	 * responsible for more than our share of that usage and
	 * we are not in a rush, request some inodedep cleanup.
	 */
	if (softdep_excess_items(ump, D_INODEDEP))
		schedule_cleanup(mp);
	else
		FREE_LOCK(ump);
	inodedep = malloc(sizeof(struct inodedep),
		M_INODEDEP, M_SOFTDEP_FLAGS);
	workitem_alloc(&inodedep->id_list, D_INODEDEP, mp);
	ACQUIRE_LOCK(ump);
	if (inodedep_find(inodedephd, inum, inodedeppp)) {
		WORKITEM_FREE(inodedep, D_INODEDEP);
		return (1);
	}
	inodedep->id_fs = fs;
	inodedep->id_ino = inum;
	inodedep->id_state = ALLCOMPLETE;
	inodedep->id_nlinkdelta = 0;
	inodedep->id_savedino1 = NULL;
	inodedep->id_savedsize = -1;
	inodedep->id_savedextsize = -1;
	inodedep->id_savednlink = -1;
	inodedep->id_bmsafemap = NULL;
	inodedep->id_mkdiradd = NULL;
	LIST_INIT(&inodedep->id_dirremhd);
	LIST_INIT(&inodedep->id_pendinghd);
	LIST_INIT(&inodedep->id_inowait);
	LIST_INIT(&inodedep->id_bufwait);
	TAILQ_INIT(&inodedep->id_inoreflst);
	TAILQ_INIT(&inodedep->id_inoupdt);
	TAILQ_INIT(&inodedep->id_newinoupdt);
	TAILQ_INIT(&inodedep->id_extupdt);
	TAILQ_INIT(&inodedep->id_newextupdt);
	TAILQ_INIT(&inodedep->id_freeblklst);
	LIST_INSERT_HEAD(inodedephd, inodedep, id_hash);
	*inodedeppp = inodedep;
	return (0);
}

/*
 * Structures and routines associated with newblk caching.
 */
#define	NEWBLK_HASH(ump, inum) \
	(&(ump)->newblk_hashtbl[(inum) & (ump)->newblk_hash_size])

static int
newblk_find(newblkhd, newblkno, flags, newblkpp)
	struct newblk_hashhead *newblkhd;
	ufs2_daddr_t newblkno;
	int flags;
	struct newblk **newblkpp;
{
	struct newblk *newblk;

	LIST_FOREACH(newblk, newblkhd, nb_hash) {
		if (newblkno != newblk->nb_newblkno)
			continue;
		/*
		 * If we're creating a new dependency don't match those that
		 * have already been converted to allocdirects.  This is for
		 * a frag extend.
		 */
		if ((flags & DEPALLOC) && newblk->nb_list.wk_type != D_NEWBLK)
			continue;
		break;
	}
	if (newblk) {
		*newblkpp = newblk;
		return (1);
	}
	*newblkpp = NULL;
	return (0);
}

/*
 * Look up a newblk. Return 1 if found, 0 if not found.
 * If not found, allocate if DEPALLOC flag is passed.
 * Found or allocated entry is returned in newblkpp.
 */
static int
newblk_lookup(mp, newblkno, flags, newblkpp)
	struct mount *mp;
	ufs2_daddr_t newblkno;
	int flags;
	struct newblk **newblkpp;
{
	struct newblk *newblk;
	struct newblk_hashhead *newblkhd;
	struct ufsmount *ump;

	ump = VFSTOUFS(mp);
	LOCK_OWNED(ump);
	newblkhd = NEWBLK_HASH(ump, newblkno);
	if (newblk_find(newblkhd, newblkno, flags, newblkpp))
		return (1);
	if ((flags & DEPALLOC) == 0)
		return (0);
	if (softdep_excess_items(ump, D_NEWBLK) ||
	    softdep_excess_items(ump, D_ALLOCDIRECT) ||
	    softdep_excess_items(ump, D_ALLOCINDIR))
		schedule_cleanup(mp);
	else
		FREE_LOCK(ump);
	newblk = malloc(sizeof(union allblk), M_NEWBLK,
	    M_SOFTDEP_FLAGS | M_ZERO);
	workitem_alloc(&newblk->nb_list, D_NEWBLK, mp);
	ACQUIRE_LOCK(ump);
	if (newblk_find(newblkhd, newblkno, flags, newblkpp)) {
		WORKITEM_FREE(newblk, D_NEWBLK);
		return (1);
	}
	newblk->nb_freefrag = NULL;
	LIST_INIT(&newblk->nb_indirdeps);
	LIST_INIT(&newblk->nb_newdirblk);
	LIST_INIT(&newblk->nb_jwork);
	newblk->nb_state = ATTACHED;
	newblk->nb_newblkno = newblkno;
	LIST_INSERT_HEAD(newblkhd, newblk, nb_hash);
	*newblkpp = newblk;
	return (0);
}

/*
 * Structures and routines associated with freed indirect block caching.
 */
#define	INDIR_HASH(ump, blkno) \
	(&(ump)->indir_hashtbl[(blkno) & (ump)->indir_hash_size])

/*
 * Lookup an indirect block in the indir hash table.  The freework is
 * removed and potentially freed.  The caller must do a blocking journal
 * write before writing to the blkno.
 */
static int
indirblk_lookup(mp, blkno)
	struct mount *mp;
	ufs2_daddr_t blkno;
{
	struct freework *freework;
	struct indir_hashhead *wkhd;
	struct ufsmount *ump;

	ump = VFSTOUFS(mp);
	wkhd = INDIR_HASH(ump, blkno);
	TAILQ_FOREACH(freework, wkhd, fw_next) {
		if (freework->fw_blkno != blkno)
			continue;
		indirblk_remove(freework);
		return (1);
	}
	return (0);
}

/*
 * Insert an indirect block represented by freework into the indirblk
 * hash table so that it may prevent the block from being re-used prior
 * to the journal being written.
 */
static void
indirblk_insert(freework)
	struct freework *freework;
{
	struct jblocks *jblocks;
	struct jseg *jseg;
	struct ufsmount *ump;

	ump = VFSTOUFS(freework->fw_list.wk_mp);
	jblocks = ump->softdep_jblocks;
	jseg = TAILQ_LAST(&jblocks->jb_segs, jseglst);
	if (jseg == NULL)
		return;
	
	LIST_INSERT_HEAD(&jseg->js_indirs, freework, fw_segs);
	TAILQ_INSERT_HEAD(INDIR_HASH(ump, freework->fw_blkno), freework,
	    fw_next);
	freework->fw_state &= ~DEPCOMPLETE;
}

static void
indirblk_remove(freework)
	struct freework *freework;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(freework->fw_list.wk_mp);
	LIST_REMOVE(freework, fw_segs);
	TAILQ_REMOVE(INDIR_HASH(ump, freework->fw_blkno), freework, fw_next);
	freework->fw_state |= DEPCOMPLETE;
	if ((freework->fw_state & ALLCOMPLETE) == ALLCOMPLETE)
		WORKITEM_FREE(freework, D_FREEWORK);
}

/*
 * Executed during filesystem system initialization before
 * mounting any filesystems.
 */
void 
softdep_initialize()
{

	TAILQ_INIT(&softdepmounts);
#ifdef __LP64__
	max_softdeps = desiredvnodes * 4;
#else
	max_softdeps = desiredvnodes * 2;
#endif

	/* initialise bioops hack */
	bioops.io_start = softdep_disk_io_initiation;
	bioops.io_complete = softdep_disk_write_complete;
	bioops.io_deallocate = softdep_deallocate_dependencies;
	bioops.io_countdeps = softdep_count_dependencies;
	softdep_ast_cleanup = softdep_ast_cleanup_proc;

	/* Initialize the callout with an mtx. */
	callout_init_mtx(&softdep_callout, &lk, 0);
}

/*
 * Executed after all filesystems have been unmounted during
 * filesystem module unload.
 */
void
softdep_uninitialize()
{

	/* clear bioops hack */
	bioops.io_start = NULL;
	bioops.io_complete = NULL;
	bioops.io_deallocate = NULL;
	bioops.io_countdeps = NULL;
	softdep_ast_cleanup = NULL;

	callout_drain(&softdep_callout);
}

/*
 * Called at mount time to notify the dependency code that a
 * filesystem wishes to use it.
 */
int
softdep_mount(devvp, mp, fs, cred)
	struct vnode *devvp;
	struct mount *mp;
	struct fs *fs;
	struct ucred *cred;
{
	struct csum_total cstotal;
	struct mount_softdeps *sdp;
	struct ufsmount *ump;
	struct cg *cgp;
	struct buf *bp;
	u_int cyl, i;
	int error;

	sdp = malloc(sizeof(struct mount_softdeps), M_MOUNTDATA,
	    M_WAITOK | M_ZERO);
	MNT_ILOCK(mp);
	mp->mnt_flag = (mp->mnt_flag & ~MNT_ASYNC) | MNT_SOFTDEP;
	if ((mp->mnt_kern_flag & MNTK_SOFTDEP) == 0) {
		mp->mnt_kern_flag = (mp->mnt_kern_flag & ~MNTK_ASYNC) | 
			MNTK_SOFTDEP | MNTK_NOASYNC;
	}
	ump = VFSTOUFS(mp);
	ump->um_softdep = sdp;
	MNT_IUNLOCK(mp);
	rw_init(LOCK_PTR(ump), "Per-Filesystem Softdep Lock");
	sdp->sd_ump = ump;
	LIST_INIT(&ump->softdep_workitem_pending);
	LIST_INIT(&ump->softdep_journal_pending);
	TAILQ_INIT(&ump->softdep_unlinked);
	LIST_INIT(&ump->softdep_dirtycg);
	ump->softdep_worklist_tail = NULL;
	ump->softdep_on_worklist = 0;
	ump->softdep_deps = 0;
	LIST_INIT(&ump->softdep_mkdirlisthd);
	ump->pagedep_hashtbl = hashinit(desiredvnodes / 5, M_PAGEDEP,
	    &ump->pagedep_hash_size);
	ump->pagedep_nextclean = 0;
	ump->inodedep_hashtbl = hashinit(desiredvnodes, M_INODEDEP,
	    &ump->inodedep_hash_size);
	ump->inodedep_nextclean = 0;
	ump->newblk_hashtbl = hashinit(max_softdeps / 2,  M_NEWBLK,
	    &ump->newblk_hash_size);
	ump->bmsafemap_hashtbl = hashinit(1024, M_BMSAFEMAP,
	    &ump->bmsafemap_hash_size);
	i = 1 << (ffs(desiredvnodes / 10) - 1);
	ump->indir_hashtbl = malloc(i * sizeof(struct indir_hashhead),
	    M_FREEWORK, M_WAITOK);
	ump->indir_hash_size = i - 1;
	for (i = 0; i <= ump->indir_hash_size; i++)
		TAILQ_INIT(&ump->indir_hashtbl[i]);
	ACQUIRE_GBLLOCK(&lk);
	TAILQ_INSERT_TAIL(&softdepmounts, sdp, sd_next);
	FREE_GBLLOCK(&lk);
	if ((fs->fs_flags & FS_SUJ) &&
	    (error = journal_mount(mp, fs, cred)) != 0) {
		printf("Failed to start journal: %d\n", error);
		softdep_unmount(mp);
		return (error);
	}
	/*
	 * Start our flushing thread in the bufdaemon process.
	 */
	ACQUIRE_LOCK(ump);
	ump->softdep_flags |= FLUSH_STARTING;
	FREE_LOCK(ump);
	kproc_kthread_add(&softdep_flush, mp, &bufdaemonproc,
	    &ump->softdep_flushtd, 0, 0, "softdepflush", "%s worker",
	    mp->mnt_stat.f_mntonname);
	ACQUIRE_LOCK(ump);
	while ((ump->softdep_flags & FLUSH_STARTING) != 0) {
		msleep(&ump->softdep_flushtd, LOCK_PTR(ump), PVM, "sdstart",
		    hz / 2);
	}
	FREE_LOCK(ump);
	/*
	 * When doing soft updates, the counters in the
	 * superblock may have gotten out of sync. Recomputation
	 * can take a long time and can be deferred for background
	 * fsck.  However, the old behavior of scanning the cylinder
	 * groups and recalculating them at mount time is available
	 * by setting vfs.ffs.compute_summary_at_mount to one.
	 */
	if (compute_summary_at_mount == 0 || fs->fs_clean != 0)
		return (0);
	bzero(&cstotal, sizeof cstotal);
	for (cyl = 0; cyl < fs->fs_ncg; cyl++) {
		if ((error = bread(devvp, fsbtodb(fs, cgtod(fs, cyl)),
		    fs->fs_cgsize, cred, &bp)) != 0) {
			brelse(bp);
			softdep_unmount(mp);
			return (error);
		}
		cgp = (struct cg *)bp->b_data;
		cstotal.cs_nffree += cgp->cg_cs.cs_nffree;
		cstotal.cs_nbfree += cgp->cg_cs.cs_nbfree;
		cstotal.cs_nifree += cgp->cg_cs.cs_nifree;
		cstotal.cs_ndir += cgp->cg_cs.cs_ndir;
		fs->fs_cs(fs, cyl) = cgp->cg_cs;
		brelse(bp);
	}
#ifdef DEBUG
	if (bcmp(&cstotal, &fs->fs_cstotal, sizeof cstotal))
		printf("%s: superblock summary recomputed\n", fs->fs_fsmnt);
#endif
	bcopy(&cstotal, &fs->fs_cstotal, sizeof cstotal);
	return (0);
}

void
softdep_unmount(mp)
	struct mount *mp;
{
	struct ufsmount *ump;
#ifdef INVARIANTS
	int i;
#endif

	KASSERT(MOUNTEDSOFTDEP(mp) != 0,
	    ("softdep_unmount called on non-softdep filesystem"));
	ump = VFSTOUFS(mp);
	MNT_ILOCK(mp);
	mp->mnt_flag &= ~MNT_SOFTDEP;
	if (MOUNTEDSUJ(mp) == 0) {
		MNT_IUNLOCK(mp);
	} else {
		mp->mnt_flag &= ~MNT_SUJ;
		MNT_IUNLOCK(mp);
		journal_unmount(ump);
	}
	/*
	 * Shut down our flushing thread. Check for NULL is if
	 * softdep_mount errors out before the thread has been created.
	 */
	if (ump->softdep_flushtd != NULL) {
		ACQUIRE_LOCK(ump);
		ump->softdep_flags |= FLUSH_EXIT;
		wakeup(&ump->softdep_flushtd);
		msleep(&ump->softdep_flags, LOCK_PTR(ump), PVM | PDROP,
		    "sdwait", 0);
		KASSERT((ump->softdep_flags & FLUSH_EXIT) == 0,
		    ("Thread shutdown failed"));
	}
	/*
	 * Free up our resources.
	 */
	ACQUIRE_GBLLOCK(&lk);
	TAILQ_REMOVE(&softdepmounts, ump->um_softdep, sd_next);
	FREE_GBLLOCK(&lk);
	rw_destroy(LOCK_PTR(ump));
	hashdestroy(ump->pagedep_hashtbl, M_PAGEDEP, ump->pagedep_hash_size);
	hashdestroy(ump->inodedep_hashtbl, M_INODEDEP, ump->inodedep_hash_size);
	hashdestroy(ump->newblk_hashtbl, M_NEWBLK, ump->newblk_hash_size);
	hashdestroy(ump->bmsafemap_hashtbl, M_BMSAFEMAP,
	    ump->bmsafemap_hash_size);
	free(ump->indir_hashtbl, M_FREEWORK);
#ifdef INVARIANTS
	for (i = 0; i <= D_LAST; i++)
		KASSERT(ump->softdep_curdeps[i] == 0,
		    ("Unmount %s: Dep type %s != 0 (%ld)", ump->um_fs->fs_fsmnt,
		    TYPENAME(i), ump->softdep_curdeps[i]));
#endif
	free(ump->um_softdep, M_MOUNTDATA);
}

static struct jblocks *
jblocks_create(void)
{
	struct jblocks *jblocks;

	jblocks = malloc(sizeof(*jblocks), M_JBLOCKS, M_WAITOK | M_ZERO);
	TAILQ_INIT(&jblocks->jb_segs);
	jblocks->jb_avail = 10;
	jblocks->jb_extent = malloc(sizeof(struct jextent) * jblocks->jb_avail,
	    M_JBLOCKS, M_WAITOK | M_ZERO);

	return (jblocks);
}

static ufs2_daddr_t
jblocks_alloc(jblocks, bytes, actual)
	struct jblocks *jblocks;
	int bytes;
	int *actual;
{
	ufs2_daddr_t daddr;
	struct jextent *jext;
	int freecnt;
	int blocks;

	blocks = bytes / DEV_BSIZE;
	jext = &jblocks->jb_extent[jblocks->jb_head];
	freecnt = jext->je_blocks - jblocks->jb_off;
	if (freecnt == 0) {
		jblocks->jb_off = 0;
		if (++jblocks->jb_head > jblocks->jb_used)
			jblocks->jb_head = 0;
		jext = &jblocks->jb_extent[jblocks->jb_head];
		freecnt = jext->je_blocks;
	}
	if (freecnt > blocks)
		freecnt = blocks;
	*actual = freecnt * DEV_BSIZE;
	daddr = jext->je_daddr + jblocks->jb_off;
	jblocks->jb_off += freecnt;
	jblocks->jb_free -= freecnt;

	return (daddr);
}

static void
jblocks_free(jblocks, mp, bytes)
	struct jblocks *jblocks;
	struct mount *mp;
	int bytes;
{

	LOCK_OWNED(VFSTOUFS(mp));
	jblocks->jb_free += bytes / DEV_BSIZE;
	if (jblocks->jb_suspended)
		worklist_speedup(mp);
	wakeup(jblocks);
}

static void
jblocks_destroy(jblocks)
	struct jblocks *jblocks;
{

	if (jblocks->jb_extent)
		free(jblocks->jb_extent, M_JBLOCKS);
	free(jblocks, M_JBLOCKS);
}

static void
jblocks_add(jblocks, daddr, blocks)
	struct jblocks *jblocks;
	ufs2_daddr_t daddr;
	int blocks;
{
	struct jextent *jext;

	jblocks->jb_blocks += blocks;
	jblocks->jb_free += blocks;
	jext = &jblocks->jb_extent[jblocks->jb_used];
	/* Adding the first block. */
	if (jext->je_daddr == 0) {
		jext->je_daddr = daddr;
		jext->je_blocks = blocks;
		return;
	}
	/* Extending the last extent. */
	if (jext->je_daddr + jext->je_blocks == daddr) {
		jext->je_blocks += blocks;
		return;
	}
	/* Adding a new extent. */
	if (++jblocks->jb_used == jblocks->jb_avail) {
		jblocks->jb_avail *= 2;
		jext = malloc(sizeof(struct jextent) * jblocks->jb_avail,
		    M_JBLOCKS, M_WAITOK | M_ZERO);
		memcpy(jext, jblocks->jb_extent,
		    sizeof(struct jextent) * jblocks->jb_used);
		free(jblocks->jb_extent, M_JBLOCKS);
		jblocks->jb_extent = jext;
	}
	jext = &jblocks->jb_extent[jblocks->jb_used];
	jext->je_daddr = daddr;
	jext->je_blocks = blocks;
	return;
}

int
softdep_journal_lookup(mp, vpp)
	struct mount *mp;
	struct vnode **vpp;
{
	struct componentname cnp;
	struct vnode *dvp;
	ino_t sujournal;
	int error;

	error = VFS_VGET(mp, UFS_ROOTINO, LK_EXCLUSIVE, &dvp);
	if (error)
		return (error);
	bzero(&cnp, sizeof(cnp));
	cnp.cn_nameiop = LOOKUP;
	cnp.cn_flags = ISLASTCN;
	cnp.cn_thread = curthread;
	cnp.cn_cred = curthread->td_ucred;
	cnp.cn_pnbuf = SUJ_FILE;
	cnp.cn_nameptr = SUJ_FILE;
	cnp.cn_namelen = strlen(SUJ_FILE);
	error = ufs_lookup_ino(dvp, NULL, &cnp, &sujournal);
	vput(dvp);
	if (error != 0)
		return (error);
	error = VFS_VGET(mp, sujournal, LK_EXCLUSIVE, vpp);
	return (error);
}

/*
 * Open and verify the journal file.
 */
static int
journal_mount(mp, fs, cred)
	struct mount *mp;
	struct fs *fs;
	struct ucred *cred;
{
	struct jblocks *jblocks;
	struct ufsmount *ump;
	struct vnode *vp;
	struct inode *ip;
	ufs2_daddr_t blkno;
	int bcount;
	int error;
	int i;

	ump = VFSTOUFS(mp);
	ump->softdep_journal_tail = NULL;
	ump->softdep_on_journal = 0;
	ump->softdep_accdeps = 0;
	ump->softdep_req = 0;
	ump->softdep_jblocks = NULL;
	error = softdep_journal_lookup(mp, &vp);
	if (error != 0) {
		printf("Failed to find journal.  Use tunefs to create one\n");
		return (error);
	}
	ip = VTOI(vp);
	if (ip->i_size < SUJ_MIN) {
		error = ENOSPC;
		goto out;
	}
	bcount = lblkno(fs, ip->i_size);	/* Only use whole blocks. */
	jblocks = jblocks_create();
	for (i = 0; i < bcount; i++) {
		error = ufs_bmaparray(vp, i, &blkno, NULL, NULL, NULL);
		if (error)
			break;
		jblocks_add(jblocks, blkno, fsbtodb(fs, fs->fs_frag));
	}
	if (error) {
		jblocks_destroy(jblocks);
		goto out;
	}
	jblocks->jb_low = jblocks->jb_free / 3;	/* Reserve 33%. */
	jblocks->jb_min = jblocks->jb_free / 10; /* Suspend at 10%. */
	ump->softdep_jblocks = jblocks;
out:
	if (error == 0) {
		MNT_ILOCK(mp);
		mp->mnt_flag |= MNT_SUJ;
		mp->mnt_flag &= ~MNT_SOFTDEP;
		MNT_IUNLOCK(mp);
		/*
		 * Only validate the journal contents if the
		 * filesystem is clean, otherwise we write the logs
		 * but they'll never be used.  If the filesystem was
		 * still dirty when we mounted it the journal is
		 * invalid and a new journal can only be valid if it
		 * starts from a clean mount.
		 */
		if (fs->fs_clean) {
			DIP_SET(ip, i_modrev, fs->fs_mtime);
			ip->i_flags |= IN_MODIFIED;
			ffs_update(vp, 1);
		}
	}
	vput(vp);
	return (error);
}

static void
journal_unmount(ump)
	struct ufsmount *ump;
{

	if (ump->softdep_jblocks)
		jblocks_destroy(ump->softdep_jblocks);
	ump->softdep_jblocks = NULL;
}

/*
 * Called when a journal record is ready to be written.  Space is allocated
 * and the journal entry is created when the journal is flushed to stable
 * store.
 */
static void
add_to_journal(wk)
	struct worklist *wk;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(wk->wk_mp);
	LOCK_OWNED(ump);
	if (wk->wk_state & ONWORKLIST)
		panic("add_to_journal: %s(0x%X) already on list",
		    TYPENAME(wk->wk_type), wk->wk_state);
	wk->wk_state |= ONWORKLIST | DEPCOMPLETE;
	if (LIST_EMPTY(&ump->softdep_journal_pending)) {
		ump->softdep_jblocks->jb_age = ticks;
		LIST_INSERT_HEAD(&ump->softdep_journal_pending, wk, wk_list);
	} else
		LIST_INSERT_AFTER(ump->softdep_journal_tail, wk, wk_list);
	ump->softdep_journal_tail = wk;
	ump->softdep_on_journal += 1;
}

/*
 * Remove an arbitrary item for the journal worklist maintain the tail
 * pointer.  This happens when a new operation obviates the need to
 * journal an old operation.
 */
static void
remove_from_journal(wk)
	struct worklist *wk;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(wk->wk_mp);
	LOCK_OWNED(ump);
#ifdef SUJ_DEBUG
	{
		struct worklist *wkn;

		LIST_FOREACH(wkn, &ump->softdep_journal_pending, wk_list)
			if (wkn == wk)
				break;
		if (wkn == NULL)
			panic("remove_from_journal: %p is not in journal", wk);
	}
#endif
	/*
	 * We emulate a TAILQ to save space in most structures which do not
	 * require TAILQ semantics.  Here we must update the tail position
	 * when removing the tail which is not the final entry. This works
	 * only if the worklist linkage are at the beginning of the structure.
	 */
	if (ump->softdep_journal_tail == wk)
		ump->softdep_journal_tail =
		    (struct worklist *)wk->wk_list.le_prev;
	WORKLIST_REMOVE(wk);
	ump->softdep_on_journal -= 1;
}

/*
 * Check for journal space as well as dependency limits so the prelink
 * code can throttle both journaled and non-journaled filesystems.
 * Threshold is 0 for low and 1 for min.
 */
static int
journal_space(ump, thresh)
	struct ufsmount *ump;
	int thresh;
{
	struct jblocks *jblocks;
	int limit, avail;

	jblocks = ump->softdep_jblocks;
	if (jblocks == NULL)
		return (1);
	/*
	 * We use a tighter restriction here to prevent request_cleanup()
	 * running in threads from running into locks we currently hold.
	 * We have to be over the limit and our filesystem has to be
	 * responsible for more than our share of that usage.
	 */
	limit = (max_softdeps / 10) * 9;
	if (dep_current[D_INODEDEP] > limit &&
	    ump->softdep_curdeps[D_INODEDEP] > limit / stat_flush_threads)
		return (0);
	if (thresh)
		thresh = jblocks->jb_min;
	else
		thresh = jblocks->jb_low;
	avail = (ump->softdep_on_journal * JREC_SIZE) / DEV_BSIZE;
	avail = jblocks->jb_free - avail;

	return (avail > thresh);
}

static void
journal_suspend(ump)
	struct ufsmount *ump;
{
	struct jblocks *jblocks;
	struct mount *mp;

	mp = UFSTOVFS(ump);
	jblocks = ump->softdep_jblocks;
	MNT_ILOCK(mp);
	if ((mp->mnt_kern_flag & MNTK_SUSPEND) == 0) {
		stat_journal_min++;
		mp->mnt_kern_flag |= MNTK_SUSPEND;
		mp->mnt_susp_owner = ump->softdep_flushtd;
	}
	jblocks->jb_suspended = 1;
	MNT_IUNLOCK(mp);
}

static int
journal_unsuspend(struct ufsmount *ump)
{
	struct jblocks *jblocks;
	struct mount *mp;

	mp = UFSTOVFS(ump);
	jblocks = ump->softdep_jblocks;

	if (jblocks != NULL && jblocks->jb_suspended &&
	    journal_space(ump, jblocks->jb_min)) {
		jblocks->jb_suspended = 0;
		FREE_LOCK(ump);
		mp->mnt_susp_owner = curthread;
		vfs_write_resume(mp, 0);
		ACQUIRE_LOCK(ump);
		return (1);
	}
	return (0);
}

/*
 * Called before any allocation function to be certain that there is
 * sufficient space in the journal prior to creating any new records.
 * Since in the case of block allocation we may have multiple locked
 * buffers at the time of the actual allocation we can not block
 * when the journal records are created.  Doing so would create a deadlock
 * if any of these buffers needed to be flushed to reclaim space.  Instead
 * we require a sufficiently large amount of available space such that
 * each thread in the system could have passed this allocation check and
 * still have sufficient free space.  With 20% of a minimum journal size
 * of 1MB we have 6553 records available.
 */
int
softdep_prealloc(vp, waitok)
	struct vnode *vp;
	int waitok;
{
	struct ufsmount *ump;

	KASSERT(MOUNTEDSOFTDEP(vp->v_mount) != 0,
	    ("softdep_prealloc called on non-softdep filesystem"));
	/*
	 * Nothing to do if we are not running journaled soft updates.
	 * If we currently hold the snapshot lock, we must avoid
	 * handling other resources that could cause deadlock.  Do not
	 * touch quotas vnode since it is typically recursed with
	 * other vnode locks held.
	 */
	if (DOINGSUJ(vp) == 0 || IS_SNAPSHOT(VTOI(vp)) ||
	    (vp->v_vflag & VV_SYSTEM) != 0)
		return (0);
	ump = VFSTOUFS(vp->v_mount);
	ACQUIRE_LOCK(ump);
	if (journal_space(ump, 0)) {
		FREE_LOCK(ump);
		return (0);
	}
	stat_journal_low++;
	FREE_LOCK(ump);
	if (waitok == MNT_NOWAIT)
		return (ENOSPC);
	/*
	 * Attempt to sync this vnode once to flush any journal
	 * work attached to it.
	 */
	if ((curthread->td_pflags & TDP_COWINPROGRESS) == 0)
		ffs_syncvnode(vp, waitok, 0);
	ACQUIRE_LOCK(ump);
	process_removes(vp);
	process_truncates(vp);
	if (journal_space(ump, 0) == 0) {
		softdep_speedup(ump);
		if (journal_space(ump, 1) == 0)
			journal_suspend(ump);
	}
	FREE_LOCK(ump);

	return (0);
}

/*
 * Before adjusting a link count on a vnode verify that we have sufficient
 * journal space.  If not, process operations that depend on the currently
 * locked pair of vnodes to try to flush space as the syncer, buf daemon,
 * and softdep flush threads can not acquire these locks to reclaim space.
 */
static void
softdep_prelink(dvp, vp)
	struct vnode *dvp;
	struct vnode *vp;
{
	struct ufsmount *ump;

	ump = VFSTOUFS(dvp->v_mount);
	LOCK_OWNED(ump);
	/*
	 * Nothing to do if we have sufficient journal space.
	 * If we currently hold the snapshot lock, we must avoid
	 * handling other resources that could cause deadlock.
	 */
	if (journal_space(ump, 0) || (vp && IS_SNAPSHOT(VTOI(vp))))
		return;
	stat_journal_low++;
	FREE_LOCK(ump);
	if (vp)
		ffs_syncvnode(vp, MNT_NOWAIT, 0);
	ffs_syncvnode(dvp, MNT_WAIT, 0);
	ACQUIRE_LOCK(ump);
	/* Process vp before dvp as it may create .. removes. */
	if (vp) {
		process_removes(vp);
		process_truncates(vp);
	}
	process_removes(dvp);
	process_truncates(dvp);
	softdep_speedup(ump);
	process_worklist_item(UFSTOVFS(ump), 2, LK_NOWAIT);
	if (journal_space(ump, 0) == 0) {
		softdep_speedup(ump);
		if (journal_space(ump, 1) == 0)
			journal_suspend(ump);
	}
}

static void
jseg_write(ump, jseg, data)
	struct ufsmount *ump;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jsegrec *rec;

	rec = (struct jsegrec *)data;
	rec->jsr_seq = jseg->js_seq;
	rec->jsr_oldest = jseg->js_oldseq;
	rec->jsr_cnt = jseg->js_cnt;
	rec->jsr_blocks = jseg->js_size / ump->um_devvp->v_bufobj.bo_bsize;
	rec->jsr_crc = 0;
	rec->jsr_time = ump->um_fs->fs_mtime;
}

static inline void
inoref_write(inoref, jseg, rec)
	struct inoref *inoref;
	struct jseg *jseg;
	struct jrefrec *rec;
{

	inoref->if_jsegdep->jd_seg = jseg;
	rec->jr_ino = inoref->if_ino;
	rec->jr_parent = inoref->if_parent;
	rec->jr_nlink = inoref->if_nlink;
	rec->jr_mode = inoref->if_mode;
	rec->jr_diroff = inoref->if_diroff;
}

static void
jaddref_write(jaddref, jseg, data)
	struct jaddref *jaddref;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jrefrec *rec;

	rec = (struct jrefrec *)data;
	rec->jr_op = JOP_ADDREF;
	inoref_write(&jaddref->ja_ref, jseg, rec);
}

static void
jremref_write(jremref, jseg, data)
	struct jremref *jremref;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jrefrec *rec;

	rec = (struct jrefrec *)data;
	rec->jr_op = JOP_REMREF;
	inoref_write(&jremref->jr_ref, jseg, rec);
}

static void
jmvref_write(jmvref, jseg, data)
	struct jmvref *jmvref;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jmvrec *rec;

	rec = (struct jmvrec *)data;
	rec->jm_op = JOP_MVREF;
	rec->jm_ino = jmvref->jm_ino;
	rec->jm_parent = jmvref->jm_parent;
	rec->jm_oldoff = jmvref->jm_oldoff;
	rec->jm_newoff = jmvref->jm_newoff;
}

static void
jnewblk_write(jnewblk, jseg, data)
	struct jnewblk *jnewblk;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jblkrec *rec;

	jnewblk->jn_jsegdep->jd_seg = jseg;
	rec = (struct jblkrec *)data;
	rec->jb_op = JOP_NEWBLK;
	rec->jb_ino = jnewblk->jn_ino;
	rec->jb_blkno = jnewblk->jn_blkno;
	rec->jb_lbn = jnewblk->jn_lbn;
	rec->jb_frags = jnewblk->jn_frags;
	rec->jb_oldfrags = jnewblk->jn_oldfrags;
}

static void
jfreeblk_write(jfreeblk, jseg, data)
	struct jfreeblk *jfreeblk;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jblkrec *rec;

	jfreeblk->jf_dep.jb_jsegdep->jd_seg = jseg;
	rec = (struct jblkrec *)data;
	rec->jb_op = JOP_FREEBLK;
	rec->jb_ino = jfreeblk->jf_ino;
	rec->jb_blkno = jfreeblk->jf_blkno;
	rec->jb_lbn = jfreeblk->jf_lbn;
	rec->jb_frags = jfreeblk->jf_frags;
	rec->jb_oldfrags = 0;
}

static void
jfreefrag_write(jfreefrag, jseg, data)
	struct jfreefrag *jfreefrag;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jblkrec *rec;

	jfreefrag->fr_jsegdep->jd_seg = jseg;
	rec = (struct jblkrec *)data;
	rec->jb_op = JOP_FREEBLK;
	rec->jb_ino = jfreefrag->fr_ino;
	rec->jb_blkno = jfreefrag->fr_blkno;
	rec->jb_lbn = jfreefrag->fr_lbn;
	rec->jb_frags = jfreefrag->fr_frags;
	rec->jb_oldfrags = 0;
}

static void
jtrunc_write(jtrunc, jseg, data)
	struct jtrunc *jtrunc;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jtrncrec *rec;

	jtrunc->jt_dep.jb_jsegdep->jd_seg = jseg;
	rec = (struct jtrncrec *)data;
	rec->jt_op = JOP_TRUNC;
	rec->jt_ino = jtrunc->jt_ino;
	rec->jt_size = jtrunc->jt_size;
	rec->jt_extsize = jtrunc->jt_extsize;
}

static void
jfsync_write(jfsync, jseg, data)
	struct jfsync *jfsync;
	struct jseg *jseg;
	uint8_t *data;
{
	struct jtrncrec *rec;

	rec = (struct jtrncrec *)data;
	rec->jt_op = JOP_SYNC;
	rec->jt_ino = jfsync->jfs_ino;
	rec->jt_size = jfsync->jfs_size;
	rec->jt_extsize = jfsync->jfs_extsize;
}

static void
softdep_flushjournal(mp)
	struct mount *mp;
{
	struct jblocks *jblocks;
	struct ufsmount *ump;

	if (MOUNTEDSUJ(mp) == 0)
		return;
	ump = VFSTOUFS(mp);
	jblocks = ump->softdep_jblocks;
	ACQUIRE_LOCK(ump);
	while (ump->softdep_on_journal) {
		jblocks->jb_needseg = 1;
		softdep_process_journal(mp, NULL, MNT_WAIT);
	}
	FREE_LOCK(ump);
}

static void softdep_synchronize_completed(struct bio *);
static void softdep_synchronize(struct bio *, struct ufsmount *, void *);

static void
softdep_synchronize_completed(bp)
        struct bio *bp;
{
	struct jseg *oldest;
	struct jseg *jseg;
	struct ufsmount *ump;

	/*
	 * caller1 marks the last segment written before we issued the
	 * synchronize cache.
	 */
	jseg = bp->bio_caller1;
	if (jseg == NULL) {
		g_destroy_bio(bp);
		return;
	}
	ump = VFSTOUFS(jseg->js_list.wk_mp);
	ACQUIRE_LOCK(ump);
	oldest = NULL;
	/*
	 * Mark all the journal entries waiting on the synchronize cache
	 * as completed so they may continue on.
	 */
	while (jseg != NULL && (jseg->js_state & COMPLETE) == 0) {
		jseg->js_state |= COMPLETE;
		oldest = jseg;
		jseg = TAILQ_PREV(jseg, jseglst, js_next);
	}
	/*
	 * Restart deferred journal entry processing from the oldest
	 * completed jseg.
	 */
	if (oldest)
		complete_jsegs(oldest);

	FREE_LOCK(ump);
	g_destroy_bio(bp);
}

/*
 * Send BIO_FLUSH/SYNCHRONIZE CACHE to the device to enforce write ordering
 * barriers.  The journal must be written prior to any blocks that depend
 * on it and the journal can not be released until the blocks have be
 * written.  This code handles both barriers simultaneously.
 */
static void
softdep_synchronize(bp, ump, caller1)
	struct bio *bp;
	struct ufsmount *ump;
	void *caller1;
{

	bp->bio_cmd = BIO_FLUSH;
	bp->bio_flags |= BIO_ORDERED;
	bp->bio_data = NULL;
	bp->bio_offset = ump->um_cp->provider->mediasize;
	bp->bio_length = 0;
	bp->bio_done = softdep_synchronize_completed;
	bp->bio_caller1 = caller1;
	g_io_request(bp,
	    (struct g_consumer *)ump->um_devvp->v_bufobj.bo_private);
}

/*
 * Flush some journal records to disk.
 */
static void
softdep_process_journal(mp, needwk, flags)
	struct mount *mp;
	struct worklist *needwk;
	int flags;
{
	struct jblocks *jblocks;
	struct ufsmount *ump;
	struct worklist *wk;
	struct jseg *jseg;
	struct buf *bp;
	struct bio *bio;
	uint8_t *data;
	struct fs *fs;
	int shouldflush;
	int segwritten;
	int jrecmin;	/* Minimum records per block. */
	int jrecmax;	/* Maximum records per block. */
	int size;
	int cnt;
	int off;
	int devbsize;

	if (MOUNTEDSUJ(mp) == 0)
		return;
	shouldflush = softdep_flushcache;
	bio = NULL;
	jseg = NULL;
	ump = VFSTOUFS(mp);
	LOCK_OWNED(ump);
	fs = ump->um_fs;
	jblocks = ump->softdep_jblocks;
	devbsize = ump->um_devvp->v_bufobj.bo_bsize;
	/*
	 * We write anywhere between a disk block and fs block.  The upper
	 * bound is picked to prevent buffer cache fragmentation and limit
	 * processing time per I/O.
	 */
	jrecmin = (devbsize / JREC_SIZE) - 1; /* -1 for seg header */
	jrecmax = (fs->fs_bsize / devbsize) * jrecmin;
	segwritten = 0;
	for (;;) {
		cnt = ump->softdep_on_journal;
		/*
		 * Criteria for writing a segment:
		 * 1) We have a full block.
		 * 2) We're called from jwait() and haven't found the
		 *    journal item yet.
		 * 3) Always write if needseg is set.
		 * 4) If we are called from process_worklist and have
		 *    not yet written anything we write a partial block
		 *    to enforce a 1 second maximum latency on journal
		 *    entries.
		 */
		if (cnt < (jrecmax - 1) && needwk == NULL &&
		    jblocks->jb_needseg == 0 && (segwritten || cnt == 0))
			break;
		cnt++;
		/*
		 * Verify some free journal space.  softdep_prealloc() should
		 * guarantee that we don't run out so this is indicative of
		 * a problem with the flow control.  Try to recover
		 * gracefully in any event.
		 */
		while (jblocks->jb_free == 0) {
			if (flags != MNT_WAIT)
				break;
			printf("softdep: Out of journal space!\n");
			softdep_speedup(ump);
			msleep(jblocks, LOCK_PTR(ump), PRIBIO, "jblocks", hz);
		}
		FREE_LOCK(ump);
		jseg = malloc(sizeof(*jseg), M_JSEG, M_SOFTDEP_FLAGS);
		workitem_alloc(&jseg->js_list, D_JSEG, mp);
		LIST_INIT(&jseg->js_entries);
		LIST_INIT(&jseg->js_indirs);
		jseg->js_state = ATTACHED;
		if (shouldflush == 0)
			jseg->js_state |= COMPLETE;
		else if (bio == NULL)
			bio = g_alloc_bio();
		jseg->js_jblocks = jblocks;
		bp = geteblk(fs->fs_bsize, 0);
		ACQUIRE_LOCK(ump);
		/*
		 * If there was a race while we were allocating the block
		 * and jseg the entry we care about was likely written.
		 * We bail out in both the WAIT and NOWAIT case and assume
		 * the caller will loop if the entry it cares about is
		 * not written.
		 */
		cnt = ump->softdep_on_journal;
		if (cnt + jblocks->jb_needseg == 0 || jblocks->jb_free == 0) {
			bp->b_flags |= B_INVAL | B_NOCACHE;
			WORKITEM_FREE(jseg, D_JSEG);
			FREE_LOCK(ump);
			brelse(bp);
			ACQUIRE_LOCK(ump);
			break;
		}
		/*
		 * Calculate the disk block size required for the available
		 * records rounded to the min size.
		 */
		if (cnt == 0)
			size = devbsize;
		else if (cnt < jrecmax)
			size = howmany(cnt, jrecmin) * devbsize;
		else
			size = fs->fs_bsize;
		/*
		 * Allocate a disk block for this journal data and account
		 * for truncation of the requested size if enough contiguous
		 * space was not available.
		 */
		bp->b_blkno = jblocks_alloc(jblocks, size, &size);
		bp->b_lblkno = bp->b_blkno;
		bp->b_offset = bp->b_blkno * DEV_BSIZE;
		bp->b_bcount = size;
		bp->b_flags &= ~B_INVAL;
		bp->b_flags |= B_VALIDSUSPWRT | B_NOCOPY;
		/*
		 * Initialize our jseg with cnt records.  Assign the next
		 * sequence number to it and link it in-order.
		 */
		cnt = MIN(cnt, (size / devbsize) * jrecmin);
		jseg->js_buf = bp;
		jseg->js_cnt = cnt;
		jseg->js_refs = cnt + 1;	/* Self ref. */
		jseg->js_size = size;
		jseg->js_seq = jblocks->jb_nextseq++;
		if (jblocks->jb_oldestseg == NULL)
			jblocks->jb_oldestseg = jseg;
		jseg->js_oldseq = jblocks->jb_oldestseg->js_seq;
		TAILQ_INSERT_TAIL(&jblocks->jb_segs, jseg, js_next);
		if (jblocks->jb_writeseg == NULL)
			jblocks->jb_writeseg = jseg;
		/*
		 * Start filling in records from the pending list.
		 */
		data = bp->b_data;
		off = 0;

		/*
		 * Always put a header on the first block.
		 * XXX As with below, there might not be a chance to get
		 * into the loop.  Ensure that something valid is written.
		 */
		jseg_write(ump, jseg, data);
		off += JREC_SIZE;
		data = bp->b_data + off;

		/*
		 * XXX Something is wrong here.  There's no work to do,
		 * but we need to perform and I/O and allow it to complete
		 * anyways.
		 */
		if (LIST_EMPTY(&ump->softdep_journal_pending))
			stat_emptyjblocks++;

		while ((wk = LIST_FIRST(&ump->softdep_journal_pending))
		    != NULL) {
			if (cnt == 0)
				break;
			/* Place a segment header on every device block. */
			if ((off % devbsize) == 0