Import the earliest version of the soft update code that I have.vendor/softdep/Jan26-97-ALPHA

3 files changed, 4622 insertions, 0 deletions

diff --git a/sys/ufs/ffs/README b/sys/ufs/ffs/README
new file mode 100644
index 000000000000..d4676c9d9452
--- /dev/null
+++ b/sys/ufs/ffs/README
@@ -0,0 +1,251 @@
+Introduction
+
+This package constitutes the alpha distribution of the soft update
+code updates for the fast filesystem.
+
+Status
+
+My `filesystem torture tests' (described below) run for days without
+a hitch (no panic's, hangs, filesystem corruption, or memory leaks).
+However, I have had several panic's reported to me by folks that
+are field testing the code which I have not yet been able to
+reproduce or fix. Although these panic's are rare and do not cause
+filesystem corruption, the code should only be put into production
+on systems where the system administrator is aware that it is being
+run, and knows how to turn it off if problems arise. Thus, you may
+hand out this code to others, but please ensure that this status
+message is included with any distributions. Please also include
+the file ffs_softdep.stub.c in any distributions so that folks that
+cannot abide by the need to redistribute source will not be left
+with a kernel that will not link. It will resolve all the calls
+into the soft update code and simply ignores the request to enable
+them. Thus you will be able to ensure that your other hooks have
+not broken anything and that your kernel is softdep-ready for those
+that wish to use them. Please report problems back to me with
+kernel backtraces of panics if possible. This is massively complex
+code, and people only have to have their filesystems hosed once or
+twice to avoid future changes like the plague. I want to find and
+fix as many bugs as soon as possible so as to get the code rock
+solid before it gets widely released. Please report any bugs that
+you uncover to mckusick@mckusick.com.
+
+Performance
+
+Running the Andrew Benchmarks yields the following raw data:
+
+	Phase	Normal	Softdep	    What it does
+	  1	  3s	  <1s	    Creating directories
+	  2	  8s	   4s	    Copying files
+	  3	  6s	   6s	    Recursive directory stats
+	  4	  8s	   9s	    Scanning each file
+	  5	 25s	  25s	    Compilation
+
+	Normal:  19.9u 29.2s 0:52.8 135+630io
+	Softdep: 20.3u 28.5s 0:47.8 103+363io
+
+Another interesting datapoint are my `filesystem torture tests'.
+They consist of 1000 runs of the andrew benchmarks, 1000 copy and
+removes of /etc with randomly selected pauses of 0-60 seconds
+between each copy and remove, and 500 find from / with randomly
+selected pauses of 100 seconds between each run). The run of the
+torture test compares as follows:
+
+With soft updates: writes: 6 sync, 1,113,686 async; run time 19hr, 50min
+Normal filesystem: writes: 1,459,147 sync, 487,031 async; run time 27hr, 15min
+
+The upshot is 42% less I/O and 28% shorter running time.
+
+Another interesting test point is a full MAKEDEV. Because it runs
+as a shell script, it becomes mostly limited by the execution speed
+of the machine on which it runs. Here are the numbers:
+
+With soft updates:
+
+	labrat# time ./MAKEDEV std
+	2.2u 32.6s 0:34.82 100.0% 0+0k 11+36io 0pf+0w
+
+	labrat# ls | wc
+	     522     522    3317
+
+Without soft updates:
+
+	labrat# time ./MAKEDEV std
+	2.0u 40.5s 0:42.53 100.0% 0+0k 11+1221io 0pf+0w
+
+	labrat# ls | wc
+	     522     522    3317
+
+Of course, some of the system time is being pushed
+to the syncer process, but that is a different story.
+
+To show a benchmark designed to highlight the soft update code
+consider a tar of zero-sized files and an rm -rf of a directory tree
+that has at least 50 files or so at each level. Running a test with
+a directory tree containing 28 directories holding 202 empty files
+produces the following numbers:
+
+With soft updates:
+tar: 0.0u 0.5s 0:00.65 76.9% 0+0k 0+44io 0pf+0w (0 sync, 33 async writes)
+rm: 0.0u 0.2s 0:00.20 100.0% 0+0k 0+37io 0pf+0w (0 sync, 72 async writes)
+
+Normal filesystem:
+tar: 0.0u 1.1s 0:07.27 16.5% 0+0k 60+586io 0pf+0w (523 sync, 0 async writes)
+rm:  0.0u 0.5s 0:01.84 29.3% 0+0k 0+318io 0pf+0w (258 sync, 65 async writes)
+
+The large reduction in writes is because inodes are clustered, so
+most of a block gets allocated, then the whole block is written
+out once rather than having the same block written once for each
+inode allocated from it.  Similarly each directory block is written
+once rather than once for each new directory entry. Effectively
+what the update code is doing is allocating a bunch of inodes
+and directory entries without writing anything, then ensuring that
+the block containing the inodes is written first followed by the
+directory block that references them.  If there were data in the
+files it would further ensure that the data blocks were written
+before their inodes claimed them.
+
+Copyright Restrictions
+
+Please familiarize yourself with the copyright restrictions
+contained at the top of either the sys/ufs/ffs/softdep.h or
+sys/ufs/ffs/ffs_softdep.c file. The key provision is similar
+to the one used by the DB 2.0 package and goes as follows:
+
+    Redistributions in any form must be accompanied by information
+    on how to obtain complete source code for any accompanying
+    software that uses the this software. This source code must
+    either be included in the distribution or be available for
+    no more than the cost of distribution plus a nominal fee,
+    and must be freely redistributable under reasonable
+    conditions. For an executable file, complete source code
+    means the source code for all modules it contains. It does
+    not mean source code for modules or files that typically
+    accompany the operating system on which the executable file
+    runs, e.g., standard library modules or system header files.
+
+The idea is to allow those of you freely redistributing your source
+to use it while retaining for myself the right to peddle it for
+money to the commercial UNIX vendors. Note that I have included a
+stub file ffs_softdep.c.stub that is freely redistributable so that
+you can put in all the necessary hooks to run the full soft updates
+code, but still allow vendors that want to maintain proprietary
+source to have a working system. I do plan to release the code with
+a `Berkeley style' copyright once I have peddled it around to the
+commercial vendors.  If you have concerns about this copyright,
+feel free to contact me with them and we can try to resolve any
+difficulties.
+
+Soft Dependency Operation
+
+The soft update implementation does NOT require ANY changes
+to the on-disk format of your filesystems. Furthermore it is
+not used by default for any filesystems. It must be enabled on
+a filesystem by filesystem basis by running tunefs to set a
+bit in the superblock indicating that the filesystem should be
+managed using soft updates. If you wish to stop using
+soft updates due to performance or reliability reasons,
+you can simply run tunefs on it again to turn off the bit and
+revert to normal operation. The additional dynamic memory load
+placed on the kernel malloc arena is approximately equal to
+the amount of memory used by vnodes plus inodes (for a system
+with 1000 vnodes, the additional peak memory load is about 300K).
+
+Kernel Changes
+
+There are two new changes to the kernel functionality that are not
+contained in in the soft update files. The first is a `trickle
+sync' facility running in the kernel as process 3.  This trickle
+sync process replaces the traditional `update' program (which should
+be commented out of the /etc/rc startup script). When a vnode is
+first written it is placed 30 seconds down on the trickle sync
+queue. If it still exists and has dirty data when it reaches the
+top of the queue, it is sync'ed.  This approach evens out the load
+on the underlying I/O system and avoids writing short-lived files.
+The papers on trickle-sync tend to favor aging based on buffers
+rather than files. However, I sync on file age rather than buffer
+age because the data structures are much smaller as there are
+typically far fewer files than buffers. Although this can make the
+I/O spikey when a big file times out, it is still much better than
+the wholesale sync's that were happening before. It also adapts
+much better to the soft update code where I want to control
+aging to improve performance (inodes age in 10 seconds, directories
+in 15 seconds, files in 30 seconds). This ensures that most
+dependencies are gone (e.g., inodes are written when directory
+entries want to go to disk) reducing the amount of rollback that
+is needed.
+
+The other main kernel change is to split the vnode freelist into
+two separate lists.  One for vnodes that are still being used to
+identify buffers and the other for those vnodes no longer identifying
+any buffers.  The latter list is used by getnewvnode in preference
+to the former.
+
+Packaging of Kernel Changes
+
+The sys subdirectory contains the changes and additions to the
+kernel. My goal in writing this code was to minimize the changes
+that need to be made to the kernel. Thus, most of the new code
+is contained in the two new files softdep.h and ffs_softdep.c.
+The rest of the kernel changes are simply inserting hooks to
+call into these two new files. Although there has been some
+structural reorganization of the filesystem code to accommodate
+gathering the information required by the soft update code,
+the actual ordering of filesystem operations when soft updates
+are disabled is unchanged.
+
+The kernel changes are packaged as a set of diffs. As I am
+doing my development in BSD/OS, the diffs are relative to the
+BSD/OS versions of the files. Because BSD/OS recently had
+4.4BSD-Lite2 merged into it, the Lite2 files are a good starting
+point for figuring out the changes. There are 40 files that
+require change plus the two new files. Most of these files have
+only a few lines of changes in them. However, four files have
+fairly extensive changes: kern/vfs_subr.c, ufs/ufs/ufs_lookup.c,
+ufs/ufs/ufs_vnops.c, and ufs/ffs/ffs_alloc.c. For these four
+files, I have provided the original Lite2 version, the Lite2
+version with the diffs merged in, and the diffs between the
+BSD/OS and merged version. Even so, I expect that there will
+be some difficulty in doing the merge; I am certainly willing
+to assist in helping get the code merged into your system.
+
+Packaging of Utility Changes
+
+The utilities subdirectory contains the changes and additions
+to the utilities. There are diffs to three utilities enclosed:
+
+    tunefs - add a flag to enable and disable soft updates
+
+    mount - print out whether soft updates are enabled and
+	    also statistics on number of sync and async writes
+
+    fsck - tighter checks on acceptable errors and a slightly
+	   different policy for what to put in lost+found on
+	   filesystems using soft updates
+
+In addition you should recompile vmstat so as to get reports
+on the 13 new memory types used by the soft update code.
+It is not necessary to use the new version of fsck, however it
+would aid in my debugging if you do. Also, because of the time
+lag between deleting a directory entry and the inode it
+references, you will find a lot more files showing up in your
+lost+found if you do not use the new version. Note that the
+new version checks for the soft update flag in the superblock
+and only uses the new algorithms if it is set. So, it will run
+unchanged on the filesystems that are not using soft updates.
+
+Operation
+
+Once you have booted a kernel that incorporates the soft update
+code and installed the updated utilities, do the following:
+
+1) Comment out the update program in /etc/rc.
+
+2) Run `tunefs -n enable' on one or more test filesystems.
+
+3) Mount these filesystems and then type `mount' to ensure that
+   they have been enabled for soft updates.
+
+4) Copy the test directory to a softdep filesystem, chdir into
+   it and run `./doit'. You may want to check out each of the
+   three subtests individually first: doit1 - andrew benchmarks,
+   doit2 - copy and removal of /etc, doit3 - find from /.
diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
new file mode 100644
index 000000000000..c60c6b2ec2eb
--- /dev/null
+++ b/sys/ufs/ffs/ffs_softdep.c
@@ -0,0 +1,3851 @@
+/*
+ * Copyright 1997 Marshall Kirk McKusick. All Rights Reserved.
+ *
+ * The soft dependency code is derived from work done by Greg Ganger
+ * at the University of Michigan.
+ *
+ * The following are the copyrights and redistribution conditions that
+ * apply to this copy of the soft dependency software. For a license
+ * to use, redistribute or sell the soft dependency software under
+ * conditions other than those described here, please contact the
+ * author at one of the following addresses:
+ *
+ *	Marshall Kirk McKusick		mckusick@mckusick.com
+ *	1614 Oxford Street		+1-510-843-9542
+ *	Berkeley, CA 94709-1608
+ *	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.
+ * 3. None of the names of McKusick, Ganger, or the University of Michigan
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * 4. Redistributions in any form must be accompanied by information on
+ *    how to obtain complete source code for any accompanying software
+ *    that uses the this software. This source code must either be included
+ *    in the distribution or be available for no more than the cost of
+ *    distribution plus a nominal fee, and must be freely redistributable
+ *    under reasonable conditions. For an executable file, complete
+ *    source code means the source code for all modules it contains.
+ *    It does not mean source code for modules or files that typically
+ *    accompany the operating system on which the executable file runs,
+ *    e.g., standard library modules or system header files.
+ *
+ * THIS SOFTWARE IS PROVIDED BY MARSHALL KIRK MCKUSICK ``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 MARSHALL KIRK MCKUSICK 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.
+ *
+ *	@(#)ffs_softdep.c	9.1 (McKusick) 7/9/97
+ */
+
+#include <sys/param.h>
+#include <sys/buf.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+#include <sys/mount.h>
+#include <sys/syslog.h>
+#include <sys/systm.h>
+#include <sys/vnode.h>
+#include <miscfs/specfs/specdev.h>
+#include <ufs/ufs/dir.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>
+
+/*
+ * Internal function prototypes.
+ */
+static	void softdep_error __P((char *, int));
+static	int getdirtybuf __P((struct buf **, int));
+static	int flush_pagedep_deps __P((struct vnode *, struct pagedep *));
+static	int flush_inodedep_deps __P((struct fs *, ino_t));
+static	int handle_written_filepage __P((struct pagedep *, struct buf *));
+static	int handle_written_inodeblock __P((struct inodedep *, struct buf *));
+static	void handle_allocdirect_partdone __P((struct allocdirect *));
+static	void handle_allocindir_partdone __P((struct allocindir *));
+static	void initiate_write_filepage __P((struct pagedep *, struct buf *));
+static	void handle_written_mkdir __P((struct mkdir *, int));
+static	void initiate_write_inodeblock __P((struct inodedep *, struct buf *));
+static	void handle_workitem_freefile __P((struct freefile *));
+static	void handle_workitem_remove __P((struct dirrem *));
+static	struct dirrem *newdirrem __P((struct buf *, struct inode *,
+	    struct inode *, int));
+static	void free_diradd __P((struct diradd *));
+static	void free_allocindir __P((struct allocindir *, struct inodedep *));
+static	int indir_trunc __P((struct inode *, ufs_daddr_t, int, ufs_lbn_t,
+	    long *));
+static	void deallocate_dependencies __P((struct buf *, struct inodedep *));
+static	void free_allocdirect __P((struct allocdirectlst *,
+	    struct allocdirect *, int));
+static	int free_inodedep __P((struct inodedep *));
+static	void handle_workitem_freeblocks __P((struct freeblks *));
+static	void merge_inode_lists __P((struct inodedep *));
+static	void setup_allocindir_phase2 __P((struct buf *, struct inode *,
+	    struct allocindir *));
+static	struct allocindir *newallocindir __P((struct inode *, int, ufs_daddr_t,
+	    ufs_daddr_t));
+static	void handle_workitem_freefrag __P((struct freefrag *));
+static	struct freefrag *newfreefrag __P((struct inode *, ufs_daddr_t, long));
+static	void allocdirect_merge __P((struct allocdirectlst *,
+	    struct allocdirect *, struct allocdirect *));
+static	struct bmsafemap *bmsafemap_lookup __P((struct buf *));
+static	int newblk_lookup __P((struct fs *, ufs_daddr_t, int,
+	    struct newblk **));
+static	int inodedep_lookup __P((struct fs *, ino_t, int, struct inodedep **));
+static	int pagedep_lookup __P((struct inode *, ufs_lbn_t, int,
+	    struct pagedep **));
+static	void add_to_worklist __P((struct worklist *));
+
+/*
+ * Exported softdep operations.
+ */
+struct bio_ops bioops = {
+	softdep_disk_io_initiation,		/* io_start */
+	softdep_disk_write_complete,		/* io_complete */
+	softdep_deallocate_dependencies,	/* io_deallocate */
+	softdep_process_worklist,		/* io_sync */
+};
+
+/*
+ * Names of malloc types.
+ */
+extern char *memname[];
+#define TYPENAME(type) ((unsigned)(type) < M_LAST ? memname[type] : "???")
+
+/*
+ * Locking primitives.
+ *
+ * For a uniprocessor, all we need to do is protect against disk
+ * interrupts. For a multiprocessor, this lock would have to be
+ * a mutex. A single mutex is used throughout this file, though
+ * finer grain locking could be used if contention warranted it.
+ *
+ * For a multiprocessor, the sleep call would accept a lock and
+ * release it after the sleep processing was complete. In a uniprocessor
+ * implementation there is no such interlock, so we simple mark
+ * the places where it needs to be done with the `interlocked' form
+ * of the lock calls. Since the uniprocessor sleep already interlocks
+ * the spl, there is nothing that really needs to be done.
+ */
+#ifndef /* NOT */ DEBUG
+static int lk;
+#define ACQUIRE_LOCK(lk)		*lk = splbio()
+#define FREE_LOCK(lk)			splx(*lk)
+#define ACQUIRE_LOCK_INTERLOCKED(lk)
+#define FREE_LOCK_INTERLOCKED(lk)
+
+#else /* DEBUG */
+#include <sys/proc.h>
+static struct lockit {
+	int	lkt_spl;
+	pid_t	lkt_held;
+} lk = { 0, -1 };
+static int lockcnt;
+
+static	void acquire_lock __P((struct lockit *));
+static	void free_lock __P((struct lockit *));
+static	void acquire_lock_interlocked __P((struct lockit *));
+static	void free_lock_interlocked __P((struct lockit *));
+
+#define ACQUIRE_LOCK(lk)		acquire_lock(lk)
+#define FREE_LOCK(lk)			free_lock(lk)
+#define ACQUIRE_LOCK_INTERLOCKED(lk)	acquire_lock_interlocked(lk)
+#define FREE_LOCK_INTERLOCKED(lk)	free_lock_interlocked(lk)
+
+static void
+acquire_lock(lk)
+	struct lockit *lk;
+{
+
+	if (lk->lkt_held != -1)
+		if (lk->lkt_held == curproc->p_pid)
+			panic("softdep_lock: locking against myself");
+		else
+			panic("softdep_lock: lock held by %d", lk->lkt_held);
+	lk->lkt_spl = splbio();
+	lk->lkt_held = curproc->p_pid;
+	lockcnt++;
+}
+
+static void
+free_lock(lk)
+	struct lockit *lk;
+{
+
+	if (lk->lkt_held == -1)
+		panic("softdep_unlock: lock not held");
+	lk->lkt_held = -1;
+	splx(lk->lkt_spl);
+}
+
+static void
+acquire_lock_interlocked(lk)
+	struct lockit *lk;
+{
+
+	if (lk->lkt_held != -1)
+		if (lk->lkt_held == curproc->p_pid)
+			panic("softdep_lock_interlocked: locking against self");
+		else
+			panic("softdep_lock_interlocked: lock held by %d",
+			    lk->lkt_held);
+	lk->lkt_held = curproc->p_pid;
+	lockcnt++;
+}
+
+static void
+free_lock_interlocked(lk)
+	struct lockit *lk;
+{
+
+	if (lk->lkt_held == -1)
+		panic("softdep_unlock_interlocked: lock not held");
+	lk->lkt_held = -1;
+}
+#endif /* DEBUG */
+
+/*
+ * Place holder for real semaphores.
+ */
+struct sema {
+	int	value;
+	pid_t	holder;
+	char	*name;
+	int	prio;
+	int	timo;
+};
+static	void sema_init __P((struct sema *, char *, int, int));
+static	int sema_get __P((struct sema *, struct lockit *));
+static	void sema_release __P((struct sema *));
+
+static void
+sema_init(semap, name, prio, timo)
+	struct sema *semap;
+	char *name;
+	int prio, timo;
+{
+
+	semap->holder = -1;
+	semap->value = 0;
+	semap->name = name;
+	semap->prio = prio;
+	semap->timo = timo;
+}
+
+static int
+sema_get(semap, interlock)
+	struct sema *semap;
+	struct lockit *interlock;
+{
+
+	if (semap->value++ > 0) {
+		if (interlock != NULL)
+			FREE_LOCK_INTERLOCKED(interlock);
+		tsleep((caddr_t)semap, semap->prio, semap->name, semap->timo);
+		if (interlock != NULL) {
+			ACQUIRE_LOCK_INTERLOCKED(interlock);
+			FREE_LOCK(interlock);
+		}
+		return (0);
+	}
+	semap->holder = curproc->p_pid;
+	if (interlock != NULL)
+		FREE_LOCK(interlock);
+	return (1);
+}
+
+static void
+sema_release(semap)
+	struct sema *semap;
+{
+
+	if (semap->value <= 0 || semap->holder != curproc->p_pid)
+		panic("sema_release: not held");
+	if (--semap->value > 0) {
+		semap->value = 0;
+		wakeup(semap);
+	}
+	semap->holder = -1;
+}
+
+/*
+ * 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 WORKITEM_FREE(item, type) FREE(item, type)
+
+#else /* DEBUG */
+static	void worklist_insert __P((struct workhead *, struct worklist *));
+static	void worklist_remove __P((struct worklist *));
+static	void workitem_free __P((struct worklist *, int));
+
+#define WORKLIST_INSERT(head, item) worklist_insert(head, item)
+#define WORKLIST_REMOVE(item) worklist_remove(item)
+#define WORKITEM_FREE(item, type) workitem_free((struct worklist *)item, type)
+
+static void
+worklist_insert(head, item)
+	struct workhead *head;
+	struct worklist *item;
+{
+
+	if (lk.lkt_held == -1)
+		panic("worklist_insert: lock not held");
+	if (item->wk_state & ONWORKLIST)
+		panic("worklist_insert: already on list");
+	item->wk_state |= ONWORKLIST;
+	LIST_INSERT_HEAD(head, item, wk_list);
+}
+
+static void
+worklist_remove(item)
+	struct worklist *item;
+{
+
+	if (lk.lkt_held == -1)
+		panic("worklist_remove: lock not held");
+	if ((item->wk_state & ONWORKLIST) == 0)
+		panic("worklist_remove: not on list");
+	item->wk_state &= ~ONWORKLIST;
+	LIST_REMOVE(item, wk_list);
+}
+
+static void
+workitem_free(item, type)
+	struct worklist *item;
+	int type;
+{
+
+	if (item->wk_state & ONWORKLIST)
+		panic("workitem_free: still on list");
+	if (item->wk_type != type)
+		panic("workitem_free: type mismatch");
+	FREE(item, type);
+}
+#endif /* DEBUG */
+
+/*
+ * Workitem queue management
+ */
+static struct workhead softdep_workitem_pending;
+static int softdep_worklist_busy;
+
+/*
+ * 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.
+ */
+static void
+add_to_worklist(wk)
+	struct worklist *wk;
+{
+	static struct worklist *worklist_tail;
+
+	if (wk->wk_state & ONWORKLIST)
+		panic("add_to_worklist: already on list");
+	wk->wk_state |= ONWORKLIST;
+	if (LIST_FIRST(&softdep_workitem_pending) == NULL)
+		LIST_INSERT_HEAD(&softdep_workitem_pending, wk, wk_list);
+	else
+		LIST_INSERT_AFTER(worklist_tail, wk, wk_list);
+	worklist_tail = wk;
+}
+
+/*
+ * 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.
+ */
+int 
+softdep_process_worklist(matchmnt)
+	struct mount *matchmnt;
+{
+	struct worklist *wk;
+	struct fs *matchfs;
+	int matchcnt;
+
+	matchcnt = 0;
+	matchfs = NULL;
+	if (matchmnt != NULL)
+		matchfs = VFSTOUFS(matchmnt)->um_fs;
+	/*
+	 * There is no danger of having multiple processes run this
+	 * code. It is single threaded solely so that softdep_flushfiles
+	 * (below) can get an accurate count of the number of items
+	 * related to its mount point that are in the list.
+	 */
+	if (softdep_worklist_busy && matchmnt == NULL)
+		return (-1);
+	ACQUIRE_LOCK(&lk);
+	while ((wk = LIST_FIRST(&softdep_workitem_pending)) != 0) {
+		WORKLIST_REMOVE(wk);
+		FREE_LOCK(&lk);
+		switch (wk->wk_type) {
+
+		case M_DIRREM:
+			/* removal of a directory entry */
+			if (WK_DIRREM(wk)->dm_mnt == matchmnt)
+				matchcnt += 1;
+			handle_workitem_remove(WK_DIRREM(wk));
+			break;
+
+		case M_FREEBLKS:
+			/* releasing blocks and/or fragments from a file */
+			if (WK_FREEBLKS(wk)->fb_fs == matchfs)
+				matchcnt += 1;
+			handle_workitem_freeblocks(WK_FREEBLKS(wk));
+			break;
+
+		case M_FREEFRAG:
+			/* releasing a fragment when replaced as a file grows */
+			if (WK_FREEFRAG(wk)->ff_fs == matchfs)
+				matchcnt += 1;
+			handle_workitem_freefrag(WK_FREEFRAG(wk));
+			break;
+
+		case M_FREEFILE:
+			/* releasing an inode when its link count drops to 0 */
+			if (WK_FREEFILE(wk)->fx_fs == matchfs)
+				matchcnt += 1;
+			handle_workitem_freefile(WK_FREEFILE(wk));
+			break;
+
+		default:
+			panic("%s_process_worklist: Unknown type %s",
+			    "softdep", TYPENAME(wk->wk_type));
+			/* NOTREACHED */
+		}
+		if (softdep_worklist_busy && matchmnt == NULL)
+			return (-1);
+		ACQUIRE_LOCK(&lk);
+	}
+	FREE_LOCK(&lk);
+	return (matchcnt);
+}
+
+/*
+ * Purge the work list of all items associated with a particular mount point.
+ */
+int
+softdep_flushfiles(oldmnt, flags, p)
+	struct mount *oldmnt;
+	int flags;
+	struct proc *p;
+{
+	struct vnode *devvp;
+	int error, loopcnt;
+
+	/*
+	 * Await our turn to clear out the queue.
+	 */
+	while (softdep_worklist_busy)
+		sleep(&lbolt, PRIBIO);
+	softdep_worklist_busy = 1;
+	if ((error = ffs_flushfiles(oldmnt, flags, p)) != 0) {
+		softdep_worklist_busy = 0;
+		return (error);
+	}
+	/*
+	 * Alternately flush the block device 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.
+	 */
+	devvp = VFSTOUFS(oldmnt)->um_devvp;
+	for (loopcnt = 10; loopcnt > 0; loopcnt--) {
+		if (softdep_process_worklist(oldmnt) == 0) {
+			/*
+			 * Do another flush in case any vnodes were brought in
+			 * as part of the cleanup operations.
+			 */
+			if ((error = ffs_flushfiles(oldmnt, flags, p)) != 0)
+				break;
+			/*
+			 * If we still found nothing to do, we are really done.
+			 */
+			if (softdep_process_worklist(oldmnt) == 0)
+				break;
+		}
+		vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY, p);
+		error = VOP_FSYNC(devvp, p->p_cred, MNT_WAIT, p);
+		VOP_UNLOCK(devvp, 0, p);
+		if (error)
+			break;
+	}
+	softdep_worklist_busy = 0;
+	if (loopcnt == 0)
+		panic("softdep_flushfiles: looping");
+	return (error);
+}
+
+/*
+ * Structure hashing.
+ * 
+ * There are three 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.
+ *
+ * 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.
+ */
+#define DEPALLOC	0x0001	/* allocate structure if lookup fails */
+
+/*
+ * Structures and routines associated with pagedep caching.
+ */
+LIST_HEAD(pagedep_hashhead, pagedep) *pagedep_hashtbl;
+u_long	pagedep_hash;		/* size of hash table - 1 */
+#define	PAGEDEP_HASH(mp, inum, lbn) \
+       (&pagedep_hashtbl[((((int)(mp)) >> 13) + (inum) + (lbn)) & pagedep_hash])
+static struct sema pagedep_in_progress;
+
+/*
+ * Look up a pagedep. Return 1 if found, 0 if not found.
+ * 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(ip, lbn, flags, pagedeppp)
+	struct inode *ip;
+	ufs_lbn_t lbn;
+	int flags;
+	struct pagedep **pagedeppp;
+{
+	struct pagedep *pagedep;
+	struct pagedep_hashhead *pagedephd;
+	struct mount *mp;
+	int i;
+
+#ifdef DEBUG
+	if (lk.lkt_held == -1)
+		panic("pagedep_lookup: lock not held");
+#endif
+	mp = ITOV(ip)->v_mount;
+	pagedephd = PAGEDEP_HASH(mp, ip->i_number, lbn);
+top:
+	for (pagedep = LIST_FIRST(pagedephd); pagedep;
+	     pagedep = LIST_NEXT(pagedep, pd_hash))
+		if (ip->i_number == pagedep->pd_ino &&
+		    lbn == pagedep->pd_lbn &&
+		    mp == pagedep->pd_mnt)
+			break;
+	if (pagedep) {
+		*pagedeppp = pagedep;
+		return (1);
+	}
+	if ((flags & DEPALLOC) == 0) {
+		*pagedeppp = NULL;
+		return (0);
+	}
+	if (sema_get(&pagedep_in_progress, &lk) == 0) {
+		ACQUIRE_LOCK(&lk);
+		goto top;
+	}
+	MALLOC(pagedep, struct pagedep *, sizeof(struct pagedep), M_PAGEDEP,
+		M_WAITOK);
+	bzero(pagedep, sizeof(struct pagedep));
+	pagedep->pd_list.wk_type = M_PAGEDEP;
+	pagedep->pd_mnt = mp;
+	pagedep->pd_ino = ip->i_number;
+	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]);
+	ACQUIRE_LOCK(&lk);
+	LIST_INSERT_HEAD(pagedephd, pagedep, pd_hash);
+	sema_release(&pagedep_in_progress);
+	*pagedeppp = pagedep;
+	return (0);
+}
+
+/*
+ * Structures and routines associated with inodedep caching.
+ */
+LIST_HEAD(inodedep_hashhead, inodedep) *inodedep_hashtbl;
+u_long	inodedep_hash;		/* size of hash table - 1 */
+#define	INODEDEP_HASH(fs, inum) \
+	(&inodedep_hashtbl[((((int)(fs)) >> 13) + (inum)) & inodedep_hash])
+static struct sema inodedep_in_progress;
+
+/*
+ * Look up a 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(fs, inum, flags, inodedeppp)
+	struct fs *fs;
+	ino_t inum;
+	int flags;
+	struct inodedep **inodedeppp;
+{
+	struct inodedep *inodedep;
+	struct inodedep_hashhead *inodedephd;
+
+#ifdef DEBUG
+	if (lk.lkt_held == -1)
+		panic("inodedep_lookup: lock not held");
+#endif
+	inodedephd = INODEDEP_HASH(fs, inum);
+top:
+	for (inodedep = LIST_FIRST(inodedephd); inodedep;
+	     inodedep = LIST_NEXT(inodedep, id_hash))
+		if (inum == inodedep->id_ino && fs == inodedep->id_fs)
+			break;
+	if (inodedep) {
+		*inodedeppp = inodedep;
+		return (1);
+	}
+	if ((flags & DEPALLOC) == 0) {
+		*inodedeppp = NULL;
+		return (0);
+	}
+	if (sema_get(&inodedep_in_progress, &lk) == 0) {
+		ACQUIRE_LOCK(&lk);
+		goto top;
+	}
+	MALLOC(inodedep, struct inodedep *, sizeof(struct inodedep),
+		M_INODEDEP, M_WAITOK);
+	inodedep->id_list.wk_type = M_INODEDEP;
+	inodedep->id_fs = fs;
+	inodedep->id_ino = inum;
+	inodedep->id_state = ALLCOMPLETE;
+	inodedep->id_nlinkdelta = 0;
+	inodedep->id_savedino = NULL;
+	inodedep->id_savedsize = -1;
+	inodedep->id_buf = NULL;
+	LIST_INIT(&inodedep->id_pendinghd);
+	LIST_INIT(&inodedep->id_inowait);
+	TAILQ_INIT(&inodedep->id_inoupdt);
+	TAILQ_INIT(&inodedep->id_newinoupdt);
+	ACQUIRE_LOCK(&lk);
+	LIST_INSERT_HEAD(inodedephd, inodedep, id_hash);
+	sema_release(&inodedep_in_progress);
+	*inodedeppp = inodedep;
+	return (0);
+}
+
+/*
+ * Structures and routines associated with newblk caching.
+ */
+LIST_HEAD(newblk_hashhead, newblk) *newblk_hashtbl;
+u_long	newblk_hash;		/* size of hash table - 1 */
+#define	NEWBLK_HASH(fs, inum) \
+	(&newblk_hashtbl[((((int)(fs)) >> 13) + (inum)) & newblk_hash])
+static struct sema newblk_in_progress;
+
+/*
+ * 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(fs, newblkno, flags, newblkpp)
+	struct fs *fs;
+	ufs_daddr_t newblkno;
+	int flags;
+	struct newblk **newblkpp;
+{
+	struct newblk *newblk;
+	struct newblk_hashhead *newblkhd;
+
+	newblkhd = NEWBLK_HASH(fs, newblkno);
+top:
+	for (newblk = LIST_FIRST(newblkhd); newblk;
+	     newblk = LIST_NEXT(newblk, nb_hash))
+		if (newblkno == newblk->nb_newblkno && fs == newblk->nb_fs)
+			break;
+	if (newblk) {
+		*newblkpp = newblk;
+		return (1);
+	}
+	if ((flags & DEPALLOC) == 0) {
+		*newblkpp = NULL;
+		return (0);
+	}
+	if (sema_get(&newblk_in_progress, 0) == 0)
+		goto top;
+	MALLOC(newblk, struct newblk *, sizeof(struct newblk),
+		M_NEWBLK, M_WAITOK);
+	newblk->nb_state = 0;
+	newblk->nb_fs = fs;
+	newblk->nb_newblkno = newblkno;
+	LIST_INSERT_HEAD(newblkhd, newblk, nb_hash);
+	sema_release(&newblk_in_progress);
+	*newblkpp = newblk;
+	return (0);
+}
+
+/*
+ * Executed during filesystem system initialization before
+ * mounting any file systems.
+ */
+void 
+softdep_initialize()
+{
+
+	LIST_INIT(&mkdirlisthd);
+	LIST_INIT(&softdep_workitem_pending);
+	pagedep_hashtbl = hashinit(desiredvnodes * 2, M_PAGEDEP, &pagedep_hash);
+	sema_init(&pagedep_in_progress, "pagedep", PRIBIO, 0);
+	inodedep_hashtbl = hashinit(desiredvnodes, M_INODEDEP, &inodedep_hash);
+	sema_init(&inodedep_in_progress, "inodedep", PRIBIO, 0);
+	newblk_hashtbl = hashinit(desiredvnodes / 10, M_NEWBLK, &newblk_hash);
+	sema_init(&newblk_in_progress, "newblk", PRIBIO, 0);
+}
+
+/*
+ * 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 cstotal;
+	struct cg *cgp;
+	struct buf *bp;
+	int error, cyl;
+
+	mp->mnt_flag |= MNT_SOFTDEP;
+	/*
+	 * When doing soft updates, the counters in the
+	 * superblock may have gotten out of sync, so we have
+	 * to scan the cylinder groups and recalculate them.
+	 */
+	if (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);
+			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("ffs_mountfs: superblock updated\n");
+#endif
+	bcopy(&cstotal, &fs->fs_cstotal, sizeof cstotal);
+	return (0);
+}
+
+/*
+ * Protecting the freemaps (or bitmaps).
+ * 
+ * To eliminate the need to execute fsck before mounting a file system
+ * after a power failure, one must (conservatively) guarantee that the
+ * on-disk copy of the bitmaps never indicate that a live inode or block is
+ * free.  So, when a block or inode is allocated, the bitmap should be
+ * updated (on disk) before any new pointers.  When a block or inode is
+ * freed, the bitmap should not be updated until all pointers have been
+ * reset.  The latter dependency is handled by the delayed de-allocation
+ * approach described below for block and inode de-allocation.  The former
+ * dependency is handled by calling the following procedure when a block or
+ * inode is allocated. When an inode is allocated an "inodedep" is created
+ * with its DEPCOMPLETE flag cleared until its bitmap is written to disk.
+ * Each "inodedep" is also inserted into the hash indexing structure so
+ * that any additional link additions can be made dependent on the inode
+ * allocation.
+ * 
+ * The ufs file system maintains a number of free block counts (e.g., per
+ * cylinder group, per cylinder and per <cylinder, rotational position> pair)
+ * in addition to the bitmaps.  These counts are used to improve efficiency
+ * during allocation and therefore must be consistent with the bitmaps.
+ * There is no convenient way to guarantee post-crash consistency of these
+ * counts with simple update ordering, for two main reasons: (1) The counts
+ * and bitmaps for a single cylinder group block are not in the same disk
+ * sector.  If a disk write is interrupted (e.g., by power failure), one may
+ * be written and the other not.  (2) Some of the counts are located in the
+ * superblock rather than the cylinder group block. So, we focus our soft
+ * updates implementation on protecting the bitmaps. When mounting a
+ * filesystem, we recompute the auxiliary counts from the bitmaps.
+ */
+
+/*
+ * Called just after updating the cylinder group block to allocate an inode.
+ */
+void
+softdep_setup_inomapdep(bp, ip, newinum)
+	struct buf *bp;		/* buffer for cylgroup block with inode map */
+	struct inode *ip;	/* inode related to allocation */
+	ino_t newinum;		/* new inode number being allocated */
+{
+	struct inodedep *inodedep;
+	struct bmsafemap *bmsafemap;
+
+	/*
+	 * Create a dependency for the newly allocated inode.
+	 * Panic if it already exists as something is seriously wrong.
+	 * Otherwise add it to the dependency list for the buffer holding
+	 * the cylinder group map from which it was allocated.
+	 */
+	ACQUIRE_LOCK(&lk);
+	if (inodedep_lookup(ip->i_fs, newinum, DEPALLOC, &inodedep) != 0)
+		panic("softdep_setup_inomapdep: found inode");
+	inodedep->id_buf = bp;
+	inodedep->id_state &= ~DEPCOMPLETE;
+	bmsafemap = bmsafemap_lookup(bp);
+	LIST_INSERT_HEAD(&bmsafemap->sm_inodedephd, inodedep, id_deps);
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Called just after updating the cylinder group block to
+ * allocate block or fragment.
+ */
+void
+softdep_setup_blkmapdep(bp, fs, newblkno)
+	struct buf *bp;		/* buffer for cylgroup block with block map */
+	struct fs *fs;		/* filesystem doing allocation */
+	ufs_daddr_t newblkno;	/* number of newly allocated block */
+{
+	struct newblk *newblk;
+	struct bmsafemap *bmsafemap;
+
+	/*
+	 * Create a dependency for the newly allocated block.
+	 * Add it to the dependency list for the buffer holding
+	 * the cylinder group map from which it was allocated.
+	 */
+	if (newblk_lookup(fs, newblkno, DEPALLOC, &newblk) != 0)
+		panic("softdep_setup_blkmapdep: found block");
+	ACQUIRE_LOCK(&lk);
+	newblk->nb_bmsafemap = bmsafemap = bmsafemap_lookup(bp);
+	LIST_INSERT_HEAD(&bmsafemap->sm_newblkhd, newblk, nb_deps);
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Find the bmsafemap associated with a cylinder group buffer.
+ * If none exists, create one. The buffer must be locked when
+ * this routine is called and this routine must be called with
+ * splbio interrupts blocked.
+ */
+static struct bmsafemap *
+bmsafemap_lookup(bp)
+	struct buf *bp;
+{
+	struct bmsafemap *bmsafemap;
+	struct worklist *wk;
+
+#ifdef DEBUG
+	if (lk.lkt_held == -1)
+		panic("bmsafemap_lookup: lock not held");
+#endif
+	for (wk = LIST_FIRST(&bp->b_dep); wk; wk = LIST_NEXT(wk, wk_list))
+		if (wk->wk_type == M_BMSAFEMAP)
+			return (WK_BMSAFEMAP(wk));
+	FREE_LOCK(&lk);
+	MALLOC(bmsafemap, struct bmsafemap *, sizeof(struct bmsafemap),
+		M_BMSAFEMAP, M_WAITOK);
+	bmsafemap->sm_list.wk_type = M_BMSAFEMAP;
+	bmsafemap->sm_list.wk_state = 0;
+	bmsafemap->sm_buf = bp;
+	LIST_INIT(&bmsafemap->sm_allocdirecthd);
+	LIST_INIT(&bmsafemap->sm_allocindirhd);
+	LIST_INIT(&bmsafemap->sm_inodedephd);
+	LIST_INIT(&bmsafemap->sm_newblkhd);
+	ACQUIRE_LOCK(&lk);
+	WORKLIST_INSERT(&bp->b_dep, &bmsafemap->sm_list);
+	return (bmsafemap);
+}
+
+/*
+ * Direct block allocation dependencies.
+ * 
+ * When a new block is allocated, the corresponding disk locations must be
+ * initialized (with zeros or new data) before the on-disk inode points to
+ * them.  Also, the freemap from which the block was allocated must be
+ * updated (on disk) before the inode's pointer. These two dependencies are
+ * independent of each other and are needed for all file blocks and indirect
+ * blocks that are pointed to directly by the inode.  Just before the
+ * "in-core" version of the inode is updated with a newly allocated block
+ * number, a procedure (below) is called to setup allocation dependency
+ * structures.  These structures are removed when the corresponding
+ * dependencies are satisfied or when the block allocation becomes obsolete
+ * (i.e., the file is deleted, the block is de-allocated, or the block is a
+ * fragment that gets upgraded).  All of these cases are handled in
+ * procedures described later.
+ * 
+ * When a file extension causes a fragment to be upgraded, either to a larger
+ * fragment or to a full block, the on-disk location may change (if the
+ * previous fragment could not simply be extended). In this case, the old
+ * fragment must be de-allocated, but not until after the inode's pointer has
+ * been updated. In most cases, this is handled by later procedures, which
+ * will construct a "freefrag" structure to be added to the workitem queue
+ * when the inode update is complete (or obsolete).  The main exception to
+ * this is when an allocation occurs while a pending allocation dependency
+ * (for the same block pointer) remains.  This case is handled in the main
+ * allocation dependency setup procedure by immediately freeing the
+ * unreferenced fragments.
+ */ 
+void 
+softdep_setup_allocdirect(ip, lbn, newblkno, oldblkno, newsize, oldsize, bp)
+	struct inode *ip;	/* inode to which block is being added */
+	ufs_lbn_t lbn;		/* block pointer within inode */
+	ufs_daddr_t newblkno;	/* disk block number being added */
+	ufs_daddr_t oldblkno;	/* previous block number, 0 unless frag */
+	long newsize;		/* size of new block */
+	long oldsize;		/* size of new block */
+	struct buf *bp;		/* bp for allocated block */
+{
+	struct allocdirect *adp, *oldadp;
+	struct allocdirectlst *adphead;
+	struct bmsafemap *bmsafemap;
+	struct inodedep *inodedep;
+	struct pagedep *pagedep;
+	struct newblk *newblk;
+
+	MALLOC(adp, struct allocdirect *, sizeof(struct allocdirect),
+		M_ALLOCDIRECT, M_WAITOK);
+	bzero(adp, sizeof(struct allocdirect));
+	adp->ad_list.wk_type = M_ALLOCDIRECT;
+	adp->ad_lbn = lbn;
+	adp->ad_newblkno = newblkno;
+	adp->ad_oldblkno = oldblkno;
+	adp->ad_newsize = newsize;
+	adp->ad_oldsize = oldsize;
+	adp->ad_state = ATTACHED;
+	if (newblkno == oldblkno)
+		adp->ad_freefrag = NULL;
+	else
+		adp->ad_freefrag = newfreefrag(ip, oldblkno, oldsize);
+
+	if (newblk_lookup(ip->i_fs, newblkno, 0, &newblk) == 0)
+		panic("softdep_setup_allocdirect: lost block");
+
+	ACQUIRE_LOCK(&lk);
+	(void) inodedep_lookup(ip->i_fs, ip->i_number, DEPALLOC, &inodedep);
+	adp->ad_inodedep = inodedep;
+
+	if (newblk->nb_state == DEPCOMPLETE) {
+		adp->ad_state |= DEPCOMPLETE;
+		adp->ad_buf = NULL;
+	} else {
+		bmsafemap = newblk->nb_bmsafemap;
+		adp->ad_buf = bmsafemap->sm_buf;
+		LIST_REMOVE(newblk, nb_deps);
+		LIST_INSERT_HEAD(&bmsafemap->sm_allocdirecthd, adp, ad_deps);
+	}
+	LIST_REMOVE(newblk, nb_hash);
+	FREE(newblk, M_NEWBLK);
+
+	WORKLIST_INSERT(&bp->b_dep, &adp->ad_list);
+	if (lbn >= NDADDR) {
+		/* allocating an indirect block */
+		if (oldblkno != 0)
+			panic("softdep_setup_allocdirect: non-zero indir");
+	} else {
+		/*
+		 * Allocating a direct block.
+		 *
+		 * If we are allocating a directory block, then we must
+		 * allocate an associated pagedep to track additions and
+		 * deletions.
+		 */
+		if ((ip->i_mode & IFMT) == IFDIR &&
+		    pagedep_lookup(ip, lbn, DEPALLOC, &pagedep) == 0)
+			WORKLIST_INSERT(&bp->b_dep, &pagedep->pd_list);
+	}
+	/*
+	 * The list of allocdirects must be kept in sorted and ascending
+	 * order so that the rollback routines can quickly determine the
+	 * first uncommitted block (the size of the file stored on disk
+	 * ends at the end of the lowest committed fragment, or if there
+	 * are no fragments, at the end of the highest committed block).
+	 * Since files generally grow, the typical case is that the new
+	 * block is to be added at the end of the list. We speed this
+	 * special case by checking against the last allocdirect in the
+	 * list before laboriously traversing the list looking for the
+	 * insertion point.
+	 */
+	adphead = &inodedep->id_newinoupdt;
+	oldadp = TAILQ_LAST(adphead, allocdirectlst);
+	if (oldadp == NULL || oldadp->ad_lbn <= lbn) {
+		/* insert at end of list */
+		TAILQ_INSERT_TAIL(adphead, adp, ad_next);
+		if (oldadp != NULL && oldadp->ad_lbn == lbn)
+			allocdirect_merge(adphead, adp, oldadp);
+		FREE_LOCK(&lk);
+		return;
+	}
+	for (oldadp = TAILQ_FIRST(adphead); oldadp;
+	     oldadp = TAILQ_NEXT(oldadp, ad_next)) {
+		if (oldadp->ad_lbn >= lbn)
+			break;
+	}
+	if (oldadp == NULL)
+		panic("softdep_setup_allocdirect: lost entry");
+	/* insert in middle of list */
+	TAILQ_INSERT_BEFORE(oldadp, adp, ad_next);
+	if (oldadp->ad_lbn == lbn)
+		allocdirect_merge(adphead, adp, oldadp);
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Replace an old allocdirect dependency with a newer one.
+ * This routine must be called with splbio interrupts blocked.
+ */
+static void
+allocdirect_merge(adphead, newadp, oldadp)
+	struct allocdirectlst *adphead;	/* head of list holding allocdirects */
+	struct allocdirect *newadp;	/* allocdirect being added */
+	struct allocdirect *oldadp;	/* existing allocdirect being checked */
+{
+	struct freefrag *freefrag;
+
+#ifdef DEBUG
+	if (lk.lkt_held == -1)
+		panic("allocdirect_merge: lock not held");
+#endif
+	if (newadp->ad_oldblkno != oldadp->ad_newblkno ||
+	    newadp->ad_oldsize != oldadp->ad_newsize ||
+	    newadp->ad_lbn >= NDADDR)
+		panic("allocdirect_check: old %d != new %d || lbn %d >= %d",
+		    newadp->ad_oldblkno, oldadp->ad_newblkno, newadp->ad_lbn,
+		    NDADDR);
+	newadp->ad_oldblkno = oldadp->ad_oldblkno;
+	newadp->ad_oldsize = oldadp->ad_oldsize;
+	/*
+	 * If the old dependency had a fragment to free or had never
+	 * previously had a block allocated, then the new dependency
+	 * can immediately post its freefrag and adopt the old freefrag.
+	 * This action is done by swapping the freefrag dependencies.
+	 * The new dependency gains the old one's freefrag, and the
+	 * old one gets the new one and then immediately puts it on
+	 * the worklist when it is freed by free_allocdirect. It is
+	 * not possible to do this swap when the old dependency had a
+	 * non-zero size but no previous fragment to free. This condition
+	 * arises when the new block is an extension of the old block.
+	 * Here, the first part of the fragment allocated to the new
+	 * dependency is part of the block currently claimed on disk by
+	 * the old dependency, so cannot legitimately be freed until the
+	 * conditions for the new dependency are fulfilled.
+	 */
+	if (oldadp->ad_freefrag != NULL || oldadp->ad_oldblkno == 0) {
+		freefrag = newadp->ad_freefrag;
+		newadp->ad_freefrag = oldadp->ad_freefrag;
+		oldadp->ad_freefrag = freefrag;
+	}
+	free_allocdirect(adphead, oldadp, 0);
+}
+		
+/*
+ * Allocate a new freefrag structure if needed.
+ */
+static struct freefrag *
+newfreefrag(ip, blkno, size)
+	struct inode *ip;
+	ufs_daddr_t blkno;
+	long size;
+{
+	struct freefrag *freefrag;
+	struct fs *fs;
+
+	if (blkno == 0)
+		return (NULL);
+	fs = ip->i_fs;
+	if (fragnum(fs, blkno) + numfrags(fs, size) > fs->fs_frag)
+		panic("newfreefrag: frag size");
+	MALLOC(freefrag, struct freefrag *, sizeof(struct freefrag),
+		M_FREEFRAG, M_WAITOK);
+	freefrag->ff_list.wk_type = M_FREEFRAG;
+	freefrag->ff_state = ip->i_uid & ~ONWORKLIST;	/* XXX - used below */
+	freefrag->ff_inum = ip->i_number;
+	freefrag->ff_fs = fs;
+	freefrag->ff_devvp = ip->i_devvp;
+	freefrag->ff_blkno = blkno;
+	freefrag->ff_fragsize = size;
+	return (freefrag);
+}
+
+/*
+ * This workitem de-allocates fragments that were replaced during
+ * file block allocation.
+ */
+static void 
+handle_workitem_freefrag(freefrag)
+	struct freefrag *freefrag;
+{
+	struct inode tip;
+
+	tip.i_fs = freefrag->ff_fs;
+	tip.i_devvp = freefrag->ff_devvp;
+	tip.i_dev = freefrag->ff_devvp->v_rdev;
+	tip.i_number = freefrag->ff_inum;
+	tip.i_uid = freefrag->ff_state & ~ONWORKLIST;	/* XXX - set above */
+	ffs_blkfree(&tip, freefrag->ff_blkno, freefrag->ff_fragsize);
+	FREE(freefrag, M_FREEFRAG);
+}
+
+/*
+ * Indirect block allocation dependencies.
+ * 
+ * The same dependencies that exist for a direct block also exist when
+ * a new block is allocated and pointed to by an entry in a block of
+ * indirect pointers. The undo/redo states described above are also
+ * used here. Because an indirect block contains many pointers that
+ * may have dependencies, a second copy of the entire in-memory indirect
+ * block is kept. The buffer cache copy is always completely up-to-date.
+ * The second copy, which is used only as a source for disk writes,
+ * contains only the safe pointers (i.e., those that have no remaining
+ * update dependencies). The second copy is freed when all pointers
+ * are safe. The cache is not allowed to replace indirect blocks with
+ * pending update dependencies. If a buffer containing an indirect
+ * block with dependencies is written, these routines will mark it
+ * dirty again. It can only be successfully written once all the
+ * dependencies are removed. The ffs_fsync routine in conjunction with
+ * softdep_sync_metadata work together to get all the dependencies
+ * removed so that a file can be successfully written to disk. Three
+ * procedures are used when setting up indirect block pointer
+ * dependencies. The division is necessary because of the organization
+ * of the "balloc" routine and because of the distinction between file
+ * pages and file metadata blocks.
+ */
+
+/*
+ * Allocate a new allocindir structure.
+ */
+static struct allocindir *
+newallocindir(ip, ptrno, newblkno, oldblkno)
+	struct inode *ip;	/* inode for file being extended */
+	int ptrno;		/* offset of pointer in indirect block */
+	ufs_daddr_t newblkno;	/* disk block number being added */
+	ufs_daddr_t oldblkno;	/* previous block number, 0 if none */
+{
+	struct allocindir *aip;
+
+	MALLOC(aip, struct allocindir *, sizeof(struct allocindir),
+		M_ALLOCINDIR, M_WAITOK);
+	bzero(aip, sizeof(struct allocindir));
+	aip->ai_list.wk_type = M_ALLOCINDIR;
+	aip->ai_state = ATTACHED;
+	aip->ai_offset = ptrno;
+	aip->ai_newblkno = newblkno;
+	aip->ai_oldblkno = oldblkno;
+	aip->ai_freefrag = newfreefrag(ip, oldblkno, ip->i_fs->fs_bsize);
+	return (aip);
+}
+
+/*
+ * Called just before setting an indirect block pointer
+ * to a newly allocated file page.
+ */
+void
+softdep_setup_allocindir_page(ip, lbn, bp, ptrno, newblkno, oldblkno, nbp)
+	struct inode *ip;	/* inode for file being extended */
+	ufs_lbn_t lbn;		/* allocated block number within file */
+	struct buf *bp;		/* buffer with indirect blk referencing page */
+	int ptrno;		/* offset of pointer in indirect block */
+	ufs_daddr_t newblkno;	/* disk block number being added */
+	ufs_daddr_t oldblkno;	/* previous block number, 0 if none */
+	struct buf *nbp;	/* buffer holding allocated page */
+{
+	struct allocindir *aip;
+	struct pagedep *pagedep;
+
+	aip = newallocindir(ip, ptrno, newblkno, oldblkno);
+	ACQUIRE_LOCK(&lk);
+	/*
+	 * If we are allocating a directory page, then we must
+	 * allocate an associated pagedep to track additions and
+	 * deletions.
+	 */
+	if ((ip->i_mode & IFMT) == IFDIR &&
+	    pagedep_lookup(ip, lbn, DEPALLOC, &pagedep) == 0)
+		WORKLIST_INSERT(&nbp->b_dep, &pagedep->pd_list);
+	WORKLIST_INSERT(&nbp->b_dep, &aip->ai_list);
+	FREE_LOCK(&lk);
+	setup_allocindir_phase2(bp, ip, aip);
+}
+
+/*
+ * Called just before setting an indirect block pointer to a
+ * newly allocated indirect block.
+ */
+void
+softdep_setup_allocindir_meta(nbp, ip, bp, ptrno, newblkno)
+	struct buf *nbp;	/* newly allocated indirect block */
+	struct inode *ip;	/* inode for file being extended */
+	struct buf *bp;		/* indirect block referencing allocated block */
+	int ptrno;		/* offset of pointer in indirect block */
+	ufs_daddr_t newblkno;	/* disk block number being added */
+{
+	struct allocindir *aip;
+
+	aip = newallocindir(ip, ptrno, newblkno, 0);
+	ACQUIRE_LOCK(&lk);
+	WORKLIST_INSERT(&nbp->b_dep, &aip->ai_list);
+	FREE_LOCK(&lk);
+	setup_allocindir_phase2(bp, ip, aip);
+}
+
+/*
+ * Called to finish the allocation of the "aip" allocated
+ * by one of the two routines above.
+ */
+static void 
+setup_allocindir_phase2(bp, ip, aip)
+	struct buf *bp;		/* in-memory copy of the indirect block */
+	struct inode *ip;	/* inode for file being extended */
+	struct allocindir *aip;	/* allocindir allocated by the above routines */
+{
+	struct worklist *wk;
+	struct indirdep *indirdep, *newindirdep;
+	struct bmsafemap *bmsafemap;
+	struct allocindir *oldaip;
+	struct freefrag *freefrag;
+	struct newblk *newblk;
+
+	if (bp->b_lblkno >= 0)
+		panic("setup_allocindir_phase2: not indir blk");
+	for (indirdep = NULL, newindirdep = NULL; ; ) {
+		ACQUIRE_LOCK(&lk);
+		for (wk = LIST_FIRST(&bp->b_dep); wk;
+		     wk = LIST_NEXT(wk, wk_list)) {
+			if (wk->wk_type != M_INDIRDEP)
+				continue;
+			indirdep = WK_INDIRDEP(wk);
+			break;
+		}
+		if (indirdep == NULL && newindirdep) {
+			indirdep = newindirdep;
+			WORKLIST_INSERT(&bp->b_dep, &indirdep->ir_list);
+			newindirdep = NULL;
+		}
+		FREE_LOCK(&lk);
+		if (indirdep) {
+			if (newblk_lookup(ip->i_fs, aip->ai_newblkno, 0,
+			    &newblk) == 0)
+				panic("setup_allocindir: lost block");
+			ACQUIRE_LOCK(&lk);
+			if (newblk->nb_state == DEPCOMPLETE) {
+				aip->ai_state |= DEPCOMPLETE;
+				aip->ai_buf = NULL;
+			} else {
+				bmsafemap = newblk->nb_bmsafemap;
+				aip->ai_buf = bmsafemap->sm_buf;
+				LIST_REMOVE(newblk, nb_deps);
+				LIST_INSERT_HEAD(&bmsafemap->sm_allocindirhd,
+				    aip, ai_deps);
+			}
+			LIST_REMOVE(newblk, nb_hash);
+			FREE(newblk, M_NEWBLK);
+			aip->ai_indirdep = indirdep;
+			/*
+			 * Check to see if there is an existing dependency
+			 * for this block. If there is, merge the old
+			 * dependency into the new one.
+			 */
+			if (aip->ai_oldblkno == 0)
+				oldaip = NULL;
+			else
+				for (oldaip=LIST_FIRST(&indirdep->ir_deplisthd);
+				    oldaip; oldaip = LIST_NEXT(oldaip, ai_next))
+					if (oldaip->ai_offset == aip->ai_offset)
+						break;
+			if (oldaip != NULL) {
+				if (oldaip->ai_newblkno != aip->ai_oldblkno)
+					panic("setup_allocindir_phase2: blkno");
+				aip->ai_oldblkno = oldaip->ai_oldblkno;
+				freefrag = oldaip->ai_freefrag;
+				oldaip->ai_freefrag = aip->ai_freefrag;
+				aip->ai_freefrag = freefrag;
+				free_allocindir(oldaip, NULL);
+			}
+			LIST_INSERT_HEAD(&indirdep->ir_deplisthd, aip, ai_next);
+			((ufs_daddr_t *)indirdep->ir_savebp->b_data)
+			    [aip->ai_offset] = aip->ai_oldblkno;
+			FREE_LOCK(&lk);
+		}
+		if (newindirdep) {
+			if (indirdep->ir_savebp != NULL)
+				brelse(newindirdep->ir_savebp);
+			WORKITEM_FREE((caddr_t)newindirdep, M_INDIRDEP);
+		}
+		if (indirdep)
+			break;
+		MALLOC(newindirdep, struct indirdep *, sizeof(struct indirdep),
+			M_INDIRDEP, M_WAITOK);
+		newindirdep->ir_list.wk_type = M_INDIRDEP;
+		newindirdep->ir_state = ATTACHED;
+		LIST_INIT(&newindirdep->ir_deplisthd);
+		LIST_INIT(&newindirdep->ir_donehd);
+		newindirdep->ir_saveddata = (ufs_daddr_t *)bp->b_data;
+		newindirdep->ir_savebp =
+		    getblk(ip->i_devvp, bp->b_blkno, bp->b_bcount, 0, 0);
+		bcopy((caddr_t)newindirdep->ir_saveddata,
+		    newindirdep->ir_savebp->b_data, bp->b_bcount);
+	}
+}
+
+/*
+ * Block de-allocation dependencies.
+ * 
+ * When blocks are de-allocated, the on-disk pointers must be nullified before
+ * the blocks are made available for use by other files.  (The true
+ * requirement is that old pointers must be nullified before new on-disk
+ * pointers are set.  We chose this slightly more stringent requirement to
+ * reduce complexity.) Our implementation handles this dependency by updating
+ * the inode (or indirect block) appropriately but delaying the actual block
+ * de-allocation (i.e., freemap and free space count manipulation) until
+ * after the updated versions reach stable storage.  After the disk is
+ * updated, the blocks can be safely de-allocated whenever it is convenient.
+ * This implementation handles only the common case of reducing a file's
+ * length to zero. Other cases are handled by the conventional synchronous
+ * write approach.
+ *
+ * The ffs implementation with which we worked double-checks
+ * the state of the block pointers and file size as it reduces
+ * a file's length.  Some of this code is replicated here in our
+ * soft updates implementation.  The freeblks->fb_chkcnt field is
+ * used to transfer a part of this information to the procedure
+ * that eventually de-allocates the blocks.
+ *
+ * This routine should be called from the routine that shortens
+ * a file's length, before the inode's size or block pointers
+ * are modified. It will save the block pointer information for
+ * later release and zero the inode so that the calling routine
+ * can release it.
+ */
+void
+softdep_setup_freeblocks(ip, length)
+	struct inode *ip;	/* The inode whose length is to be reduced */
+	off_t length;		/* The new length for the file */
+{
+	struct freeblks *freeblks;
+	struct inodedep *inodedep;
+	struct allocdirect *adp;
+	struct vnode *vp;
+	struct buf *bp;
+	struct fs *fs;
+	int i, error;
+
+	fs = ip->i_fs;
+	if (length != 0)
+		panic("softde_setup_freeblocks: non-zero length");
+	MALLOC(freeblks, struct freeblks *, sizeof(struct freeblks),
+		M_FREEBLKS, M_WAITOK);
+	bzero(freeblks, sizeof(struct freeblks));
+	freeblks->fb_list.wk_type = M_FREEBLKS;
+	freeblks->fb_uid = ip->i_uid;
+	freeblks->fb_previousinum = ip->i_number;
+	freeblks->fb_devvp = ip->i_devvp;
+	freeblks->fb_fs = fs;
+	freeblks->fb_oldsize = ip->i_size;
+	freeblks->fb_newsize = length;
+	freeblks->fb_chkcnt = ip->i_blocks;
+	for (i = 0; i < NDADDR; i++) {
+		freeblks->fb_dblks[i] = ip->i_db[i];
+		ip->i_db[i] = 0;
+	}
+	for (i = 0; i < NIADDR; i++) {
+		freeblks->fb_iblks[i] = ip->i_ib[i];
+		ip->i_ib[i] = 0;
+	}
+	ip->i_blocks = 0;
+	ip->i_size = 0;
+	/*
+	 * Push the zero'ed inode to to its disk buffer so that we are free
+	 * to delete its dependencies below. Once the dependencies are gone
+	 * the buffer can be safely released.
+	 */
+	if ((error = bread(ip->i_devvp,
+	    fsbtodb(fs, ino_to_fsba(fs, ip->i_number)),
+	    (int)fs->fs_bsize, NOCRED, &bp)) != 0)
+		softdep_error("softdep_setup_freeblocks", error);
+	*((struct dinode *)bp->b_data + ino_to_fsbo(fs, ip->i_number)) =
+	    ip->i_din;
+	/*
+	 * Find and eliminate any inode dependencies.
+	 */
+	ACQUIRE_LOCK(&lk);
+	(void) inodedep_lookup(fs, ip->i_number, DEPALLOC, &inodedep);
+	if ((inodedep->id_state & IOSTARTED) != 0)
+		panic("softdep_setup_freeblocks: inode busy");
+	/*
+	 * Add the freeblks structure to the list of operations that
+	 * must await the zero'ed inode being written to disk.
+	 */
+	WORKLIST_INSERT(&inodedep->id_inowait, &freeblks->fb_list);
+	/*
+	 * Because the file length has been truncated to zero, any
+	 * pending block allocation dependency structures associated
+	 * with this inode are obsolete and can simply be de-allocated.
+	 * We must first merge the two dependency lists to get rid of
+	 * any duplicate freefrag structures, then purge the merged list.
+	 */
+	merge_inode_lists(inodedep);
+	while ((adp = TAILQ_FIRST(&inodedep->id_inoupdt)) != 0)
+		free_allocdirect(&inodedep->id_inoupdt, adp, 1);
+	bdwrite(bp);
+	/*
+	 * We must wait for any I/O in progress to finish so that
+	 * all potential buffers on the dirty list will be visible.
+	 * Once they are all there, walk the list and get rid of
+	 * any dependencies.
+	 */
+	vp = ITOV(ip);
+	while (vp->v_numoutput) {
+		vp->v_flag |= VBWAIT;
+		FREE_LOCK_INTERLOCKED(&lk);
+		sleep((caddr_t)&vp->v_numoutput, PRIBIO + 1);
+		ACQUIRE_LOCK_INTERLOCKED(&lk);
+	}
+	while (getdirtybuf(&LIST_FIRST(&vp->v_dirtyblkhd), MNT_WAIT)) {
+		bp = LIST_FIRST(&vp->v_dirtyblkhd);
+		(void) inodedep_lookup(fs, ip->i_number, 0, &inodedep);
+		deallocate_dependencies(bp, inodedep);
+		bp->b_flags |= B_INVAL;
+		brelse(bp);
+	}
+	/*
+	 * Try freeing the inodedep in case that was the last dependency.
+	 */
+	if ((inodedep_lookup(fs, ip->i_number, 0, &inodedep)) != 0)
+		(void) free_inodedep(inodedep);
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Reclaim any dependency structures from a buffer that is about to
+ * be reallocated to a new vnode. The buffer must be locked, thus,
+ * no I/O completion operations can occur while we are manipulating
+ * its associated dependencies. The mutex is held so that other I/O's
+ * associated with related dependencies do not occur.
+ */
+static void
+deallocate_dependencies(bp, inodedep)
+	struct buf *bp;
+	struct inodedep *inodedep;
+{
+	struct worklist *wk;
+	struct indirdep *indirdep;
+	struct allocindir *aip;
+	struct pagedep *pagedep;
+	struct dirrem *dirrem;
+	struct diradd *dap;
+	long tmpsize;
+	caddr_t tmp;
+	int i;
+
+	while ((wk = LIST_FIRST(&bp->b_dep)) != NULL) {
+		switch (wk->wk_type) {
+
+		case M_INDIRDEP:
+			indirdep = WK_INDIRDEP(wk);
+			/*
+			 * None of the indirect pointers will ever be visible,
+			 * so they can simply be tossed. GOINGAWAY ensures
+			 * that allocated pointers will be saved in the buffer
+			 * cache until they are freed. Note that they will
+			 * only be able to be found by their physical address
+			 * since the inode mapping the logical address will
+			 * be gone. The save buffer used for the safe copy
+			 * was allocated in setup_allocindir_phase2 using
+			 * the physical address so it could be used for this
+			 * purpose. Hence we swap the safe copy with the real
+			 * copy, allowing the safe copy to be freed and holding
+			 * on to the real copy for later use in indir_trunc.
+			 */
+			if (indirdep->ir_state & GOINGAWAY)
+				panic("deallocate_dependencies: already gone");
+			indirdep->ir_state |= GOINGAWAY;
+			while ((aip = LIST_FIRST(&indirdep->ir_deplisthd)) != 0)
+				free_allocindir(aip, inodedep);
+			if (bp->b_lblkno >= 0 ||
+			    bp->b_blkno != indirdep->ir_savebp->b_lblkno)
+				panic("deallocate_dependencies: not indir");
+			tmp = indirdep->ir_savebp->b_data;
+			indirdep->ir_savebp->b_data = bp->b_data;
+			bp->b_data = tmp;
+			tmpsize = indirdep->ir_savebp->b_bufsize;
+			indirdep->ir_savebp->b_bufsize = bp->b_bufsize;
+			bp->b_bufsize = tmpsize;
+			WORKLIST_REMOVE(wk);
+			WORKLIST_INSERT(&indirdep->ir_savebp->b_dep, wk);
+			continue;
+
+		case M_PAGEDEP:
+			pagedep = WK_PAGEDEP(wk);
+			/*
+			 * None of the directory additions will ever be
+			 * visible, so they can simply be tossed.
+			 */
+			for (i = 0; i < DAHASHSZ; i++)
+				while (dap=LIST_FIRST(&pagedep->pd_diraddhd[i]))
+					free_diradd(dap);
+			while ((dap = LIST_FIRST(&pagedep->pd_pendinghd)) != 0)
+				free_diradd(dap);
+			/*
+			 * Copy any directory remove dependencies to the list
+			 * to be processed after the zero'ed inode is written.
+			 * If the inode has already been written, then they 
+			 * can be dumped directly onto the work list.
+			 */
+			for (dirrem = LIST_FIRST(&pagedep->pd_dirremhd); dirrem;
+			     dirrem = LIST_NEXT(dirrem, dm_next)) {
+				LIST_REMOVE(dirrem, dm_next);
+				dirrem->dm_dirinum = pagedep->pd_ino;
+				if (inodedep == NULL)
+					add_to_worklist(&dirrem->dm_list);
+				else
+					WORKLIST_INSERT(&inodedep->id_inowait,
+					    &dirrem->dm_list);
+			}
+			WORKLIST_REMOVE(&pagedep->pd_list);
+			LIST_REMOVE(pagedep, pd_hash);
+			WORKITEM_FREE(pagedep, M_PAGEDEP);
+			continue;
+
+		case M_ALLOCINDIR:
+			free_allocindir(WK_ALLOCINDIR(wk), inodedep);
+			continue;
+
+		case M_ALLOCDIRECT:
+		case M_INODEDEP:
+			panic("deallocate_dependencies: Unexpected type %s",
+			    TYPENAME(wk->wk_type));
+			/* NOTREACHED */
+
+		default:
+			panic("deallocate_dependencies: Unknown type %s",
+			    TYPENAME(wk->wk_type));
+			/* NOTREACHED */
+		}
+	}
+}
+
+/*
+ * Free an allocdirect. Generate a new freefrag work request if appropriate.
+ * This routine must be called with splbio interrupts blocked.
+ */
+static void
+free_allocdirect(adphead, adp, delay)
+	struct allocdirectlst *adphead;
+	struct allocdirect *adp;
+	int delay;
+{
+
+#ifdef DEBUG
+	if (lk.lkt_held == -1)
+		panic("free_allocdirect: lock not held");
+#endif
+	if ((adp->ad_state & DEPCOMPLETE) == 0)
+		LIST_REMOVE(adp, ad_deps);
+	TAILQ_REMOVE(adphead, adp, ad_next);
+	if ((adp->ad_state & COMPLETE) == 0)
+		WORKLIST_REMOVE(&adp->ad_list);
+	if (adp->ad_freefrag != NULL) {
+		if (delay)
+			WORKLIST_INSERT(&adp->ad_inodedep->id_inowait,
+			    &adp->ad_freefrag->ff_list);
+		else
+			add_to_worklist(&adp->ad_freefrag->ff_list);
+	}
+	WORKITEM_FREE(adp, M_ALLOCDIRECT);
+}
+
+/*
+ * Prepare an inode to be freed. The actual free operation is not
+ * done until the zero'ed inode has been written to disk.
+ */
+void
+softdep_freefile(ap)
+	struct vop_vfree_args /* {
+		struct vnode *a_pvp;
+		ino_t a_ino;
+		int a_mode;
+	} */ *ap;
+{
+	struct inode *ip = VTOI(ap->a_pvp);
+	struct inodedep *inodedep;
+	struct freefile *freefile;
+
+	/*
+	 * This sets up the inode de-allocation dependency.
+	 */
+	MALLOC(freefile, struct freefile *, sizeof(struct freefile),
+		M_FREEFILE, M_WAITOK);
+	freefile->fx_list.wk_type = M_FREEFILE;
+	freefile->fx_list.wk_state = 0;
+	freefile->fx_mode = ap->a_mode;
+	freefile->fx_oldinum = ap->a_ino;
+	freefile->fx_devvp = ip->i_devvp;
+	freefile->fx_fs = ip->i_fs;
+
+	/*
+	 * If the inodedep does not exist, then the zero'ed inode has
+	 * been written to disk and we can free the file immediately.
+	 */
+	ACQUIRE_LOCK(&lk);
+	if (inodedep_lookup(ip->i_fs, ap->a_ino, 0, &inodedep) == 0) {
+		add_to_worklist(&freefile->fx_list);
+		FREE_LOCK(&lk);
+		return;
+	}
+
+	/*
+	 * If we still have a bitmap dependency, then the inode has never
+	 * been written to disk. Drop the dependency as it is no longer
+	 * necessary since the inode is being deallocated. We could process
+	 * the freefile immediately, but then we would have to clear the
+	 * id_inowait dependencies here and it is easier just to let the
+	 * zero'ed inode be written and let them be cleaned up in the
+	 * normal followup actions that follow the inode write.
+	 */
+	 if ((inodedep->id_state & DEPCOMPLETE) == 0) {
+		inodedep->id_state |= DEPCOMPLETE;
+		LIST_REMOVE(inodedep, id_deps);
+		inodedep->id_buf = NULL;
+	}
+	/*
+	 * If the inodedep has no dependencies associated with it,
+	 * then we must free it here and free the file immediately.
+	 * This case arises when an early allocation fails (for
+	 * example, the user is over their file quota).
+	 */
+	if (free_inodedep(inodedep) == 0)
+		WORKLIST_INSERT(&inodedep->id_inowait, &freefile->fx_list);
+	else
+		add_to_worklist(&freefile->fx_list);
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Try to free an inodedep structure. Return 1 if it could be freed.
+ */
+static int
+free_inodedep(inodedep)
+	struct inodedep *inodedep;
+{
+
+	if ((inodedep->id_state & ONWORKLIST) != 0 ||
+	    LIST_FIRST(&inodedep->id_pendinghd) != NULL ||
+	    LIST_FIRST(&inodedep->id_inowait) != NULL ||
+	    TAILQ_FIRST(&inodedep->id_inoupdt) != NULL ||
+	    TAILQ_FIRST(&inodedep->id_newinoupdt) != NULL ||
+	    inodedep->id_nlinkdelta != 0 || inodedep->id_buf != NULL ||
+	    inodedep->id_savedino != NULL)
+		return (0);
+	LIST_REMOVE(inodedep, id_hash);
+	WORKITEM_FREE(inodedep, M_INODEDEP);
+	return (1);
+}
+
+/*
+ * This workitem routine performs the block de-allocation.
+ * The workitem is added to the pending list after the updated
+ * inode block has been written to disk.  As mentioned above,
+ * checks regarding the number of blocks de-allocated (compared
+ * to the number of blocks allocated for the file) are also
+ * performed in this function.
+ */
+static void
+handle_workitem_freeblocks(freeblks)
+	struct freeblks *freeblks;
+{
+	struct inode tip;
+	ufs_daddr_t bn;
+	struct fs *fs;
+	int i, level, bsize;
+	long nblocks, blocksreleased = 0;
+	int error, allerror = 0;
+	ufs_lbn_t baselbns[NIADDR], tmpval;
+
+	tip.i_number = freeblks->fb_previousinum;
+	tip.i_devvp = freeblks->fb_devvp;
+	tip.i_dev = freeblks->fb_devvp->v_rdev;
+	tip.i_fs = freeblks->fb_fs;
+	tip.i_size = freeblks->fb_oldsize;
+	tip.i_uid = freeblks->fb_uid;
+	fs = freeblks->fb_fs;
+	tmpval = 1;
+	baselbns[0] = NDADDR;
+	for (i = 1; i < NIADDR; i++) {
+		tmpval *= NINDIR(fs);
+		baselbns[i] = baselbns[i - 1] + tmpval;
+	}
+	nblocks = btodb(fs->fs_bsize);
+	blocksreleased = 0;
+	/*
+	 * Indirect blocks first.
+	 */
+	for (level = (NIADDR - 1); level >= 0; level--) {
+		if ((bn = freeblks->fb_iblks[level]) == 0)
+			continue;
+		if ((error = indir_trunc(&tip, fsbtodb(fs, bn), level,
+		    baselbns[level], &blocksreleased)) == 0)
+			allerror = error;
+		ffs_blkfree(&tip, bn, fs->fs_bsize);
+		blocksreleased += nblocks;
+	}
+	/*
+	 * All direct blocks or frags.
+	 */
+	for (i = (NDADDR - 1); i >= 0; i--) {
+		if ((bn = freeblks->fb_dblks[i]) == 0)
+			continue;
+		bsize = blksize(fs, &tip, i);
+		ffs_blkfree(&tip, bn, bsize);
+		blocksreleased += btodb(bsize);
+	}
+
+#ifdef DIAGNOSTIC
+	if (freeblks->fb_chkcnt != blocksreleased)
+		panic("handle_workitem_freeblocks: block count");
+	if (allerror)
+		softdep_error("handle_workitem_freeblks", allerror);
+#endif /* DIAGNOSTIC */
+	WORKITEM_FREE(freeblks, M_FREEBLKS);
+}
+
+/*
+ * Release blocks associated with the inode ip and stored in the indirect
+ * block dbn. If level is greater than SINGLE, the block is an indirect block
+ * and recursive calls to indirtrunc must be used to cleanse other indirect
+ * blocks.
+ */
+static int
+indir_trunc(ip, dbn, level, lbn, countp)
+	struct inode *ip;
+	ufs_daddr_t dbn;
+	int level;
+	ufs_lbn_t lbn;
+	long *countp;
+{
+	struct buf *bp;
+	ufs_daddr_t *bap;
+	ufs_daddr_t nb;
+	struct fs *fs;
+	struct worklist *wk;
+	struct indirdep *indirdep;
+	int i, lbnadd, nblocks;
+	int error, allerror = 0;
+
+	fs = ip->i_fs;
+	lbnadd = 1;
+	for (i = level; i > 0; i--)
+		lbnadd *= NINDIR(fs);
+	/*
+	 * Get buffer of block pointers to be freed. This routine is not
+	 * called until the zero'ed inode has been written, so it is safe
+	 * to free blocks as they are encountered. Because the inode has
+	 * been zero'ed, calls to bmap on these blocks will fail. So, we
+	 * have to use the on-disk address and the block device for the
+	 * filesystem to look them up. If the file was deleted before its
+	 * indirect blocks were all written to disk, the routine that set
+	 * us up (deallocate_dependencies) will have arranged to leave
+	 * a complete copy of the indirect block in memory for our use.
+	 * Otherwise we have to read the blocks in from the disk.
+	 */
+	ACQUIRE_LOCK(&lk);
+	if ((bp = incore(ip->i_devvp, dbn)) != NULL &&
+	    (wk = LIST_FIRST(&bp->b_dep)) != NULL) {
+		if (wk->wk_type != M_INDIRDEP ||
+		    (indirdep = WK_INDIRDEP(wk))->ir_savebp != bp ||
+		    (indirdep->ir_state & GOINGAWAY) == 0)
+			panic("indir_trunc: lost indirdep");
+		WORKLIST_REMOVE(wk);
+		WORKITEM_FREE(indirdep, M_INDIRDEP);
+		if (LIST_FIRST(&bp->b_dep) != NULL)
+			panic("indir_trunc: dangling dep");
+		FREE_LOCK(&lk);
+	} else {
+		FREE_LOCK(&lk);
+		error = bread(ip->i_devvp, dbn, (int)fs->fs_bsize, NOCRED, &bp);
+		if (error)
+			return (error);
+	}
+	/*
+	 * Recursively free indirect blocks.
+	 */
+	bap = (ufs_daddr_t *)bp->b_data;
+	nblocks = btodb(fs->fs_bsize);
+	for (i = NINDIR(fs) - 1; i >= 0; i--) {
+		if ((nb = bap[i]) == 0)
+			continue;
+		if (level != 0) {
+			if ((error = indir_trunc(ip, fsbtodb(fs, nb),
+			     level - 1, lbn + (i * lbnadd), countp)) != 0)
+				allerror = error;
+		}
+		ffs_blkfree(ip, nb, fs->fs_bsize);
+		*countp += nblocks;
+	}
+	bp->b_flags |= B_INVAL;
+	brelse(bp);
+	return (allerror);
+}
+
+/*
+ * Free an allocindir.
+ * This routine must be called with splbio interrupts blocked.
+ */
+static void
+free_allocindir(aip, inodedep)
+	struct allocindir *aip;
+	struct inodedep *inodedep;
+{
+	struct freefrag *freefrag;
+
+#ifdef DEBUG
+	if (lk.lkt_held == -1)
+		panic("free_allocindir: lock not held");
+#endif
+	if ((aip->ai_state & DEPCOMPLETE) == 0)
+		LIST_REMOVE(aip, ai_deps);
+	if (aip->ai_state & ONWORKLIST)
+		WORKLIST_REMOVE(&aip->ai_list);
+	LIST_REMOVE(aip, ai_next);
+	if ((freefrag = aip->ai_freefrag) != NULL) {
+		if (inodedep == NULL)
+			add_to_worklist(&freefrag->ff_list);
+		else
+			WORKLIST_INSERT(&inodedep->id_inowait,
+			    &freefrag->ff_list);
+	}
+	WORKITEM_FREE(aip, M_ALLOCINDIR);
+}
+
+/*
+ * Directory entry addition dependencies.
+ * 
+ * When adding a new directory entry, the inode (with its incremented link
+ * count) must be written to disk before the directory entry's pointer to it.
+ * Also, if the inode is newly allocated, the corresponding freemap must be
+ * updated (on disk) before the directory entry's pointer. These requirements
+ * are met via undo/redo on the directory entry's pointer, which consists
+ * simply of the inode number.
+ * 
+ * As directory entries are added and deleted, the free space within a
+ * directory block can become fragmented.  The ufs file system will compact
+ * a fragmented directory block to make space for a new entry. When this
+ * occurs, the offsets of previously added entries change. Any "diradd"
+ * dependency structures corresponding to these entries must be updated with
+ * the new offsets.
+ */
+
+/*
+ * This routine is called after the in-memory inode's link
+ * count has been incremented, but before the directory entry's
+ * pointer to the inode has been set.
+ */
+void 
+softdep_setup_directory_add(bp, dp, diroffset, newinum, newdirbp)
+	struct buf *bp;		/* buffer containing directory block */
+	struct inode *dp;	/* inode for directory */
+	off_t diroffset;	/* offset of new entry in directory */
+	long newinum;		/* inode referenced by new directory entry */
+	struct buf *newdirbp;	/* non-NULL => contents of new mkdir */
+{
+	int offset;		/* offset of new entry within directory block */
+	ufs_lbn_t lbn;		/* block in directory containing new entry */
+	struct fs *fs;
+	struct diradd *dap;
+	struct pagedep *pagedep;
+	struct inodedep *inodedep;
+	struct mkdir *mkdir1, *mkdir2;
+
+	/*
+	 * Whiteouts have no dependencies.
+	 */
+	if (newinum == WINO) {
+		if (newdirbp != NULL)
+			bdwrite(newdirbp);
+		return;
+	}
+
+	fs = dp->i_fs;
+	lbn = lblkno(fs, diroffset);
+	offset = blkoff(fs, diroffset);
+	MALLOC(dap, struct diradd *, sizeof(struct diradd), M_DIRADD, M_WAITOK);
+	bzero(dap, sizeof(struct diradd));
+	dap->da_list.wk_type = M_DIRADD;
+	dap->da_offset = offset;
+	dap->da_newinum = newinum;
+	dap->da_state = ATTACHED;
+	if (newdirbp == NULL) {
+		dap->da_state |= DEPCOMPLETE;
+	} else {
+		dap->da_state |= MKDIR_BODY | MKDIR_PARENT;
+		MALLOC(mkdir1, struct mkdir *, sizeof(struct mkdir), M_MKDIR,
+		    M_WAITOK);
+		mkdir1->md_list.wk_type = M_MKDIR;
+		mkdir1->md_state = MKDIR_BODY;
+		mkdir1->md_diradd = dap;
+		MALLOC(mkdir2, struct mkdir *, sizeof(struct mkdir), M_MKDIR,
+		    M_WAITOK);
+		mkdir2->md_list.wk_type = M_MKDIR;
+		mkdir2->md_state = MKDIR_PARENT;
+		mkdir2->md_diradd = dap;
+
+	}
+
+	ACQUIRE_LOCK(&lk);
+	/*
+	 * If this directory entry references a new directory, create
+	 * its two additional dependencies: its "." and ".." being written
+	 * to disk and the link count increase for its parent directory.
+	 */
+	if (newdirbp != NULL) {
+		/*
+		 * Dependency on "." and ".." being written to disk
+		 */
+		LIST_INSERT_HEAD(&mkdirlisthd, mkdir1, md_mkdirs);
+		WORKLIST_INSERT(&newdirbp->b_dep, &mkdir1->md_list);
+		bdwrite(newdirbp);
+		/*
+		 * Dependency on link count increase for parent directory
+		 */
+		if (inodedep_lookup(dp->i_fs, dp->i_number, 0, &inodedep) == 0
+		    || (inodedep->id_state & ALLCOMPLETE) == ALLCOMPLETE) {
+			dap->da_state &= ~MKDIR_PARENT;
+			WORKITEM_FREE(mkdir2, M_MKDIR);
+		} else {
+			LIST_INSERT_HEAD(&mkdirlisthd, mkdir2, md_mkdirs);
+			WORKLIST_INSERT(&inodedep->id_inowait,&mkdir2->md_list);
+		}
+	}
+	/*
+	 * Link into parent directory pagedep and new inode inodedep
+	 * structures to await its being written.
+	 */
+	if (pagedep_lookup(dp, lbn, DEPALLOC, &pagedep) == 0)
+		WORKLIST_INSERT(&bp->b_dep, &pagedep->pd_list);
+	dap->da_pagedep = pagedep;
+	LIST_INSERT_HEAD(&pagedep->pd_diraddhd[DIRADDHASH(offset)], dap,
+	    da_pdlist);
+	if (inodedep_lookup(fs, newinum, DEPALLOC, &inodedep) == 1 &&
+	    (inodedep->id_state & ALLCOMPLETE) == ALLCOMPLETE)
+		WORKLIST_INSERT(&inodedep->id_pendinghd, &dap->da_list);
+	else
+		WORKLIST_INSERT(&inodedep->id_inowait, &dap->da_list);
+	FREE_LOCK(&lk);
+}
+
+/*
+ * This procedure is called to change the offset of a directory
+ * entry when compacting a directory block which must be owned
+ * exclusively by the caller. Note that the actual entry movement
+ * must be done in this procedure to ensure that no I/O completions
+ * occur while the move is in progress.
+ */
+void 
+softdep_change_directoryentry_offset(dp, base, oldloc, newloc, entrysize)
+	struct inode *dp;	/* inode for directory */
+	caddr_t base;		/* address of dp->i_offset */
+	caddr_t oldloc;		/* address of old directory location */
+	caddr_t newloc;		/* address of new directory location */
+	int entrysize;		/* size of directory entry */
+{
+	int oldoffset, newoffset;
+	struct pagedep *pagedep;
+	struct diradd *dap;
+	ufs_lbn_t lbn;
+
+	ACQUIRE_LOCK(&lk);
+	lbn = lblkno(dp->i_fs, dp->i_offset);
+	if (pagedep_lookup(dp, lbn, 0, &pagedep) == 0)
+		goto done;
+	oldoffset = dp->i_offset + (oldloc - base);
+	newoffset = dp->i_offset + (newloc - base);
+	for (dap = LIST_FIRST(&pagedep->pd_diraddhd[DIRADDHASH(oldoffset)]);
+	     dap; dap = LIST_NEXT(dap, da_pdlist)) {
+		if (dap->da_offset != oldoffset)
+			continue;
+		dap->da_offset = newoffset;
+		if (DIRADDHASH(newoffset) == DIRADDHASH(oldoffset))
+			break;
+		LIST_REMOVE(dap, da_pdlist);
+		LIST_INSERT_HEAD(&pagedep->pd_diraddhd[DIRADDHASH(newoffset)],
+		    dap, da_pdlist);
+		break;
+	}
+done:
+	bcopy(oldloc, newloc, entrysize);
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Free a diradd dependency structure. This routine must be called
+ * with splbio interrupts blocked.
+ */
+static void
+free_diradd(dap)
+	struct diradd *dap;
+{
+	struct dirrem *dirrem;
+	struct pagedep *pagedep;
+	struct inodedep *inodedep;
+	struct mkdir *mkdir, *nextmd;
+
+#ifdef DEBUG
+	if (lk.lkt_held == -1)
+		panic("free_diradd: lock not held");
+#endif
+	WORKLIST_REMOVE(&dap->da_list);
+	LIST_REMOVE(dap, da_pdlist);
+	if ((dap->da_state & DIRCHG) == 0) {
+		pagedep = dap->da_pagedep;
+	} else {
+		dirrem = dap->da_previous;
+		pagedep = dirrem->dm_pagedep;
+		LIST_INSERT_HEAD(&pagedep->pd_dirremhd, dirrem, dm_next);
+	}
+	if (inodedep_lookup(VFSTOUFS(pagedep->pd_mnt)->um_fs, dap->da_newinum,
+	    0, &inodedep) != 0)
+		(void) free_inodedep(inodedep);
+	if ((dap->da_state & (MKDIR_PARENT | MKDIR_BODY)) != 0) {
+		for (mkdir = LIST_FIRST(&mkdirlisthd); mkdir; mkdir = nextmd) {
+			nextmd = LIST_NEXT(mkdir, md_mkdirs);
+			if (mkdir->md_diradd != dap)
+				continue;
+			dap->da_state &= ~mkdir->md_state;
+			WORKLIST_REMOVE(&mkdir->md_list);
+			LIST_REMOVE(mkdir, md_mkdirs);
+			WORKITEM_FREE(mkdir, M_MKDIR);
+		}
+		if ((dap->da_state & (MKDIR_PARENT | MKDIR_BODY)) != 0)
+			panic("free_diradd: unfound ref");
+	}
+	WORKITEM_FREE(dap, M_DIRADD);
+}
+
+/*
+ * Directory entry removal dependencies.
+ * 
+ * When removing a directory entry, the entry's inode pointer must be
+ * zero'ed on disk before the corresponding inode's link count is decremented
+ * (possibly freeing the inode for re-use). This dependency is handled by
+ * updating the directory entry but delaying the inode count reduction until
+ * after the directory block has been written to disk. After this point, the
+ * inode count can be decremented whenever it is convenient.
+ */
+
+/*
+ * This routine should be called immediately after removing
+ * a directory entry.  The inode's link count should not be
+ * decremented by the calling procedure -- the soft updates
+ * code will do this task when it is safe.
+ */
+void 
+softdep_setup_remove(bp, dp, ip, isrmdir)
+	struct buf *bp;		/* buffer containing directory block */
+	struct inode *dp;	/* inode for the directory being modified */
+	struct inode *ip;	/* inode for directory entry being removed */
+	int isrmdir;		/* indicates if doing RMDIR */
+{
+	struct dirrem *dirrem;
+
+	/*
+	 * Allocate a new dirrem if appropriate and ACQUIRE_LOCK.
+	 */
+	dirrem = newdirrem(bp, dp, ip, isrmdir);
+	if ((dirrem->dm_state & COMPLETE) == 0) {
+		LIST_INSERT_HEAD(&dirrem->dm_pagedep->pd_dirremhd, dirrem,
+		    dm_next);
+	} else {
+		dirrem->dm_dirinum = dirrem->dm_pagedep->pd_ino;
+		add_to_worklist(&dirrem->dm_list);
+	}
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Allocate a new dirrem if appropriate and return it along with
+ * its associated pagedep. Called without a lock, returns with lock.
+ */
+static struct dirrem *
+newdirrem(bp, dp, ip, isrmdir)
+	struct buf *bp;		/* buffer containing directory block */
+	struct inode *dp;	/* inode for the directory being modified */
+	struct inode *ip;	/* inode for directory entry being removed */
+	int isrmdir;		/* indicates if doing RMDIR */
+{
+	ufs_lbn_t lbn;
+	struct diradd *dap;
+	struct dirrem *dirrem;
+	struct pagedep *pagedep;
+
+	/*
+	 * Whiteouts have no deletion dependencies.
+	 */
+	if (ip == NULL)
+		panic("newdirrem: whiteout");
+	MALLOC(dirrem, struct dirrem *, sizeof(struct dirrem),
+		M_DIRREM, M_WAITOK);
+	bzero(dirrem, sizeof(struct dirrem));
+	dirrem->dm_list.wk_type = M_DIRREM;
+	dirrem->dm_state = isrmdir ? RMDIR : 0;
+	dirrem->dm_mnt = ITOV(ip)->v_mount;
+	dirrem->dm_oldinum = ip->i_number;
+
+	ACQUIRE_LOCK(&lk);
+	lbn = lblkno(dp->i_fs, dp->i_offset);
+	if (pagedep_lookup(dp, lbn, DEPALLOC, &pagedep) == 0)
+		WORKLIST_INSERT(&bp->b_dep, &pagedep->pd_list);
+	dirrem->dm_pagedep = pagedep;
+	for (dap = LIST_FIRST(&pagedep->pd_diraddhd[DIRADDHASH(dp->i_offset)]);
+	     dap; dap = LIST_NEXT(dap, da_pdlist)) {
+		/*
+		 * Check for a diradd dependency for the same directory entry.
+		 * If present, then both dependencies become obsolete and can
+		 * be de-allocated.
+		 */
+		if (dap->da_offset != dp->i_offset)
+			continue;
+		/*
+		 * Must be ATTACHED at this point, so just delete it.
+		 */
+		if ((dap->da_state & ATTACHED) == 0)
+			panic("newdirrem: not ATTACHED");
+		if (dap->da_newinum != ip->i_number)
+			panic("newdirrem: inum %d should be %d",
+			    ip->i_number, dap->da_newinum);
+		free_diradd(dap);
+		dirrem->dm_state |= COMPLETE;
+		break;
+	}
+	return (dirrem);
+}
+
+/*
+ * Directory entry change dependencies.
+ * 
+ * Changing an existing directory entry requires that an add operation
+ * be completed first followed by a deletion. The semantics for the addition
+ * are identical to the description of adding a new entry above except
+ * that the rollback is to the old inode number rather than zero. Once
+ * the addition dependency is completed, the removal is done as described
+ * in the removal routine above.
+ */
+
+/*
+ * This routine should be called immediately after changing
+ * a directory entry.  The inode's link count should not be
+ * decremented by the calling procedure -- the soft updates
+ * code will perform this task when it is safe.
+ */
+void 
+softdep_setup_directory_change(bp, dp, ip, newinum, isrmdir)
+	struct buf *bp;		/* buffer containing directory block */
+	struct inode *dp;	/* inode for the directory being modified */
+	struct inode *ip;	/* inode for directory entry being removed */
+	long newinum;		/* new inode number for changed entry */
+	int isrmdir;		/* indicates if doing RMDIR */
+{
+	int offset;
+	struct diradd *dap;
+	struct dirrem *dirrem;
+	struct inodedep *inodedep;
+
+	offset = blkoff(dp->i_fs, dp->i_offset);
+
+	/*
+	 * Whiteouts have no addition dependencies.
+	 */
+	if (newinum == WINO) {
+		dap = NULL;
+	} else {
+		MALLOC(dap, struct diradd *, sizeof(struct diradd),
+		    M_DIRADD, M_WAITOK);
+		bzero(dap, sizeof(struct diradd));
+		dap->da_list.wk_type = M_DIRADD;
+		dap->da_state = DIRCHG | ATTACHED | DEPCOMPLETE;
+		dap->da_offset = offset;
+		dap->da_newinum = newinum;
+	}
+
+	/*
+	 * Allocate a new dirrem if appropriate and ACQUIRE_LOCK.
+	 */
+	dirrem = newdirrem(bp, dp, ip, isrmdir);
+
+	/*
+	 * If the inode has already been written, then no addition
+	 * dependency needs to be created.
+	 */
+	if (inodedep_lookup(dp->i_fs, newinum, 0, &inodedep) == 0 ||
+	    (inodedep->id_state & ALLCOMPLETE) == ALLCOMPLETE) {
+		WORKITEM_FREE(dap, M_DIRADD);
+		dap = NULL;
+	}
+
+	if (dap) {
+		dap->da_previous = dirrem;
+		LIST_INSERT_HEAD(
+		    &dirrem->dm_pagedep->pd_diraddhd[DIRADDHASH(offset)],
+		    dap, da_pdlist);
+		WORKLIST_INSERT(&inodedep->id_inowait, &dap->da_list);
+	} else if ((dirrem->dm_state & COMPLETE) == 0) {
+		LIST_INSERT_HEAD(&dirrem->dm_pagedep->pd_dirremhd, dirrem,
+		    dm_next);
+	} else {
+		dirrem->dm_dirinum = dirrem->dm_pagedep->pd_ino;
+		add_to_worklist(&dirrem->dm_list);
+	}
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Called whenever the link count on an inode is increased.
+ * It creates an inode dependency so that the new reference(s)
+ * to the inode cannot be committed to disk until the updated
+ * inode has been written.
+ */
+void
+softdep_increase_linkcnt(ip)
+	struct inode *ip;	/* the inode with the increased link count */
+{
+	struct inodedep *inodedep;
+
+	ACQUIRE_LOCK(&lk);
+	(void) inodedep_lookup(ip->i_fs, ip->i_number, DEPALLOC, &inodedep);
+	FREE_LOCK(&lk);
+}
+
+/*
+ * This workitem decrements the inode's link count.
+ * If the link count reaches zero, the file is removed.
+ */
+static void 
+handle_workitem_remove(dirrem)
+	struct dirrem *dirrem;
+{
+	struct proc *p = curproc;	/* XXX */
+	struct inodedep *inodedep;
+	struct vnode *vp;
+	struct inode *ip;
+	int error;
+
+	if ((error = VFS_VGET(dirrem->dm_mnt, dirrem->dm_oldinum, &vp)) != 0) {
+		softdep_error("handle_workitem_remove: vget", error);
+		return;
+	}
+	ip = VTOI(vp);
+	/*
+	 * Normal file deletion.
+	 */
+	if ((dirrem->dm_state & RMDIR) == 0) {
+		ip->i_nlink--;
+		if (ip->i_nlink < ip->i_effnlink)
+			panic("handle_workitem_remove: bad file delta");
+		ip->i_flag |= IN_CHANGE;
+		vput(vp);
+		WORKITEM_FREE(dirrem, M_DIRREM);
+		return;
+	}
+	/*
+	 * Directory deletion. Decrement reference count for both the
+	 * just deleted parent directory entry and the reference for ".".
+	 * Next truncate the directory to length zero. When the
+	 * truncation completes, arrange to have the reference count on
+	 * the parent decremented to account for the loss of "..".
+	 */
+	ip->i_nlink -= 2;
+	if (ip->i_nlink < ip->i_effnlink)
+		panic("handle_workitem_remove: bad dir delta");
+	ip->i_flag |= IN_CHANGE;
+	if ((error = VOP_TRUNCATE(vp, (off_t)0, 0, p->p_cred, p)) != 0)
+		softdep_error("handle_workitem_remove: truncate", error);
+	ACQUIRE_LOCK(&lk);
+	(void) inodedep_lookup(ip->i_fs, dirrem->dm_oldinum, DEPALLOC,
+	    &inodedep);
+	dirrem->dm_state = 0;
+	dirrem->dm_oldinum = dirrem->dm_dirinum;
+	WORKLIST_INSERT(&inodedep->id_inowait, &dirrem->dm_list);
+	FREE_LOCK(&lk);
+	vput(vp);
+}
+
+/*
+ * Inode de-allocation dependencies.
+ * 
+ * When an inode's link count is reduced to zero, it can be de-allocated. We
+ * found it convenient to postpone de-allocation until after the inode is
+ * written to disk with its new link count (zero).  At this point, all of the
+ * on-disk inode's block pointers are nullified and, with careful dependency
+ * list ordering, all dependencies related to the inode will be satisfied and
+ * the corresponding dependency structures de-allocated.  So, if/when the
+ * inode is reused, there will be no mixing of old dependencies with new
+ * ones.  This artificial dependency is set up by the block de-allocation
+ * procedure above (softdep_setup_freeblocks) and completed by the
+ * following procedure.
+ */
+static void 
+handle_workitem_freefile(freefile)
+	struct freefile *freefile;
+{
+	struct vnode vp;
+	struct inode tip;
+	struct inodedep *idp;
+	struct vop_vfree_args args;
+	int error;
+
+#ifdef DEBUG
+	ACQUIRE_LOCK(&lk);
+	if (inodedep_lookup(freefile->fx_fs, freefile->fx_oldinum, 0, &idp))
+		panic("handle_workitem_freefile: inodedep survived");
+	FREE_LOCK(&lk);
+#endif
+	tip.i_devvp = freefile->fx_devvp;
+	tip.i_dev = freefile->fx_devvp->v_rdev;
+	tip.i_fs = freefile->fx_fs;
+	vp.v_data = &tip;
+	args.a_pvp = &vp;
+	args.a_ino = freefile->fx_oldinum;
+	args.a_mode = freefile->fx_mode;
+	if ((error = ffs_freefile(&args)) != 0)
+		softdep_error("handle_workitem_freefile", error);
+	WORKITEM_FREE(freefile, M_FREEFILE);
+}
+
+/*
+ * Disk writes.
+ * 
+ * The dependency structures constructed above are most actively used when file
+ * system blocks are written to disk.  No constraints are placed on when a
+ * block can be written, but unsatisfied update dependencies are made safe by
+ * modifying (or replacing) the source memory for the duration of the disk
+ * write.  When the disk write completes, the memory block is again brought
+ * up-to-date.
+ *
+ * In-core inode structure reclamation.
+ * 
+ * Because there are a finite number of "in-core" inode structures, they are
+ * reused regularly.  By transferring all inode-related dependencies to the
+ * in-memory inode block and indexing them separately (via "inodedep"s), we
+ * can allow "in-core" inode structures to be reused at any time and avoid
+ * any increase in contention.
+ *
+ * Called just before entering the device driver to initiate a new disk I/O.
+ * The buffer must be locked, thus, no I/O completion operations can occur
+ * while we are manipulating its associated dependencies.
+ */
+void 
+softdep_disk_io_initiation(bp)
+	struct buf *bp;		/* structure describing disk write to occur */
+{
+	struct worklist *wk, *nextwk;
+	struct indirdep *indirdep;
+
+	/*
+	 * We only care about write operations. There should never
+	 * be dependencies for reads.
+	 */
+	if (bp->b_flags & B_READ)
+		panic("softdep_disk_io_initiation: read");
+	/*
+	 * Do any necessary pre-I/O processing.
+	 */
+	for (wk = LIST_FIRST(&bp->b_dep); wk; wk = nextwk) {
+		nextwk = LIST_NEXT(wk, wk_list);
+		switch (wk->wk_type) {
+
+		case M_PAGEDEP:
+			initiate_write_filepage(WK_PAGEDEP(wk), bp);
+			continue;
+
+		case M_INODEDEP:
+			initiate_write_inodeblock(WK_INODEDEP(wk), bp);
+			continue;
+
+		case M_INDIRDEP:
+			indirdep = WK_INDIRDEP(wk);
+			if (indirdep->ir_state & GOINGAWAY)
+				panic("disk_io_initiation: indirdep gone");
+			/*
+			 * If there are no remaining dependencies, this
+			 * will be writing the real pointers, so the
+			 * dependency can be freed.
+			 */
+			if (LIST_FIRST(&indirdep->ir_deplisthd) == NULL) {
+				brelse(indirdep->ir_savebp);
+				/* inline expand WORKLIST_REMOVE(wk); */
+				wk->wk_state &= ~ONWORKLIST;
+				LIST_REMOVE(wk, wk_list);
+				WORKITEM_FREE(indirdep, M_INDIRDEP);
+				continue;
+			}
+			/*
+			 * Replace up-to-date version with safe version.
+			 */
+			ACQUIRE_LOCK(&lk);
+			indirdep->ir_state &= ~ATTACHED;
+			indirdep->ir_state |= UNDONE;
+			bp->b_data = indirdep->ir_savebp->b_data;
+			FREE_LOCK(&lk);
+			continue;
+
+		case M_MKDIR:
+		case M_BMSAFEMAP:
+		case M_ALLOCDIRECT:
+		case M_ALLOCINDIR:
+			continue;
+
+		default:
+			panic("handle_disk_io_initiation: Unexpected type %s",
+			    TYPENAME(wk->wk_type));
+			/* NOTREACHED */
+		}
+	}
+}
+
+/*
+ * Called from within the procedure above to deal with unsatisfied
+ * allocation dependencies in a directory. The buffer must be locked,
+ * thus, no I/O completion operations can occur while we are
+ * manipulating its associated dependencies.
+ */
+static void
+initiate_write_filepage(pagedep, bp)
+	struct pagedep *pagedep;
+	struct buf *bp;
+{
+	struct diradd *dap;
+	struct direct *ep;
+	int i;
+
+	if (pagedep->pd_state & IOSTARTED) {
+		/*
+		 * This can only happen if there is a driver that does not
+		 * understand chaining. Here biodone will reissue the call
+		 * to strategy for the incomplete buffers.
+		 */
+		printf("initiate_write_filepage: already started\n");
+		return;
+	}
+	pagedep->pd_state |= IOSTARTED;
+	ACQUIRE_LOCK(&lk);
+	for (i = 0; i < DAHASHSZ; i++) {
+		for (dap = LIST_FIRST(&pagedep->pd_diraddhd[i]); dap;
+		     dap = LIST_NEXT(dap, da_pdlist)) {
+			ep = (struct direct *)
+			    ((char *)bp->b_data + dap->da_offset);
+			if (ep->d_ino != dap->da_newinum)
+				panic("%s: dir inum %d != new %d",
+				    "initiate_write_filepage",
+				    ep->d_ino, dap->da_newinum);
+			if (dap->da_state & DIRCHG)
+				ep->d_ino = dap->da_previous->dm_oldinum;
+			else
+				ep->d_ino = 0;
+			dap->da_state &= ~ATTACHED;
+			dap->da_state |= UNDONE;
+		}
+	}
+	FREE_LOCK(&lk);
+}
+
+/*
+ * Called from within the procedure above to deal with unsatisfied
+ * allocation dependencies in an inodeblock. The buffer must be
+ * locked, thus, no I/O completion operations can occur while we
+ * are manipulating its associated dependencies.
+ */
+static void 
+initiate_write_inodeblock(inodedep, bp)
+	struct inodedep *inodedep;
+	struct buf *bp;			/* The inode block */
+{
+	struct allocdirect *adp, *lastadp;
+	struct dinode *dp;
+	struct fs *fs;
+	ufs_lbn_t prevlbn;
+	int i, deplist;
+
+	if (inodedep->id_state & IOSTARTED)
+		panic("initiate_write_inodeblock: already started");
+	inodedep->id_state |= IOSTARTED;
+	fs = inodedep->id_fs;
+	dp = (struct dinode *)bp->b_data +
+	    ino_to_fsbo(fs, inodedep->id_ino);
+	/*
+	 * If the bitmap is not yet written, then the allocated
+	 * inode cannot be written to disk.
+	 */
+	if ((inodedep->id_state & DEPCOMPLETE) == 0) {
+		if (inodedep->id_savedino != NULL)
+			panic("initiate_write_inodeblock: already doing I/O");
+		MALLOC(inodedep->id_savedino, struct dinode *,
+		    sizeof(struct dinode), M_INODEDEP, M_WAITOK);
+		*inodedep->id_savedino = *dp;
+		bzero((caddr_t)dp, sizeof(struct dinode));
+		return;
+	}
+	/*
+	 * If no dependencies, then there is nothing to roll back.
+	 */
+	inodedep->id_savedsize = dp->di_size;
+	if (TAILQ_FIRST(&inodedep->id_inoupdt) == NULL)
+		return;
+	/*
+	 * Set the dependencies to busy.
+	 */
+	ACQUIRE_LOCK(&lk);
+	for (deplist = 0, adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp;
+	     adp = TAILQ_NEXT(adp, ad_next)) {
+#ifdef DIAGNOSTIC
+		if (deplist != 0 && prevlbn >= adp->ad_lbn)
+			panic("softdep_write_inodeblock: lbn order");
+		prevlbn = adp->ad_lbn;
+		if (adp->ad_lbn < NDADDR &&
+		    dp->di_db[adp->ad_lbn] != adp->ad_newblkno)
+			panic("%s: direct pointer #%d mismatch %d != %d",
+			    "softdep_write_inodeblock", adp->ad_lbn,
+			    dp->di_db[adp->ad_lbn], adp->ad_newblkno);
+		if (adp->ad_lbn >= NDADDR &&
+		    dp->di_ib[adp->ad_lbn - NDADDR] != adp->ad_newblkno)
+			panic("%s: indirect pointer #%d mismatch %d != %d",
+			    "softdep_write_inodeblock", adp->ad_lbn - NDADDR,
+			    dp->di_ib[adp->ad_lbn - NDADDR], adp->ad_newblkno);
+		deplist |= 1 << adp->ad_lbn;
+		if ((adp->ad_state & ATTACHED) == 0)
+			panic("softdep_write_inodeblock: Unknown state 0x%x",
+			    adp->ad_state);
+#endif /* DIAGNOSTIC */
+		adp->ad_state &= ~ATTACHED;
+		adp->ad_state |= UNDONE;
+	}
+	/*
+	 * The on-disk inode cannot claim to be any larger than the last
+	 * fragment that has been written. Otherwise, the on-disk inode
+	 * might have fragments that were not the last block in the file
+	 * which would corrupt the filesystem.
+	 */
+	for (lastadp = NULL, adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp;
+	     lastadp = adp, adp = TAILQ_NEXT(adp, ad_next)) {
+		if (adp->ad_lbn >= NDADDR)
+			break;
+		dp->di_db[adp->ad_lbn] = adp->ad_oldblkno;
+		/* keep going until hitting a rollback to a frag */
+		if (adp->ad_oldsize == 0 || adp->ad_oldsize == fs->fs_bsize)
+			continue;
+		dp->di_size = fs->fs_bsize * adp->ad_lbn + adp->ad_oldsize;
+		for (i = adp->ad_lbn + 1; i < NDADDR; i++) {
+#ifdef DIAGNOSTIC
+			if (dp->di_db[i] != 0 && (deplist & (1 << i)) == 0)
+				panic("softdep_write_inodeblock: lost dep1");
+#endif /* DIAGNOSTIC */
+			dp->di_db[i] = 0;
+		}
+		for (i = 0; i < NIADDR; i++) {
+#ifdef DIAGNOSTIC
+			if (dp->di_ib[i] != 0 &&
+			    (deplist & ((1 << NDADDR) << i)) == 0)
+				panic("softdep_write_inodeblock: lost dep2");
+#endif /* DIAGNOSTIC */
+			dp->di_ib[i] = 0;
+		}
+		FREE_LOCK(&lk);
+		return;
+	}
+	/*
+	 * If we have zero'ed out the last allocated block of the file,
+	 * roll back the size to the last currently allocated block.
+	 * We know that this last allocated block is a full-sized as
+	 * we already checked for fragments in the loop above.
+	 */
+	if (lastadp != NULL &&
+	    dp->di_size <= (lastadp->ad_lbn + 1) * fs->fs_bsize) {
+		for (i = lastadp->ad_lbn; i >= 0; i--)
+			if (dp->di_db[i] != 0)
+				break;
+		dp->di_size = (i + 1) * fs->fs_bsize;
+	}
+	/*
+	 * The only dependencies are for indirect blocks.
+	 *
+	 * The file size for indirect block additions is not guaranteed.
+	 * Such a guarantee would be non-trivial to achieve. The conventional
+	 * synchronous write implementation also does not make this guarantee.
+	 * Fsck should catch and fix discrepancies. Arguably, the file size
+	 * can be over-estimated without destroying integrity when the file
+	 * moves into the indirect blocks (i.e., is large). If we want to
+	 * postpone fsck, we are stuck with this argument.
+	 */
+	for (; adp; adp = TAILQ_NEXT(adp, ad_next))
+		dp->di_ib[adp->ad_lbn - NDADDR] = 0;
+	FREE_LOCK(&lk);
+}
+
+/*
+ * This routine is called during the completion interrupt
+ * service routine for a disk write (from the procedure called
+ * by the device driver to inform the file system caches of
+ * a request completion).  It should be called early in this
+ * procedure, before the block is made available to other
+ * processes or other routines are called.
+ */
+void 
+softdep_disk_write_complete(bp)
+	struct buf *bp;		/* describes the completed disk write */
+{
+	struct worklist *wk;
+	struct workhead reattach;
+	struct newblk *newblk;
+	struct allocindir *aip;
+	struct allocdirect *adp;
+	struct indirdep *indirdep;
+	struct inodedep *inodedep;
+	struct bmsafemap *bmsafemap;
+
+#ifdef DEBUG
+	if (lk.lkt_held != -1)
+		panic("softdep_disk_write_complete: lock is held");
+	lk.lkt_held = -2;
+#endif
+	LIST_INIT(&reattach);
+	while ((wk = LIST_FIRST(&bp->b_dep)) != NULL) {
+		WORKLIST_REMOVE(wk);
+		switch (wk->wk_type) {
+
+		case M_PAGEDEP:
+			if (handle_written_filepage(WK_PAGEDEP(wk), bp))
+				WORKLIST_INSERT(&reattach, wk);
+			continue;
+
+		case M_INODEDEP:
+			if (handle_written_inodeblock(WK_INODEDEP(wk), bp))
+				WORKLIST_INSERT(&reattach, wk);
+			continue;
+
+		case M_BMSAFEMAP:
+			bmsafemap = WK_BMSAFEMAP(wk);
+			while (newblk = LIST_FIRST(&bmsafemap->sm_newblkhd)) {
+				newblk->nb_state |= DEPCOMPLETE;
+				newblk->nb_bmsafemap = NULL;
+				LIST_REMOVE(newblk, nb_deps);
+			}
+			while (adp = LIST_FIRST(&bmsafemap->sm_allocdirecthd)) {
+				adp->ad_state |= DEPCOMPLETE;
+				adp->ad_buf = NULL;
+				LIST_REMOVE(adp, ad_deps);
+				handle_allocdirect_partdone(adp);
+			}
+			while (aip = LIST_FIRST(&bmsafemap->sm_allocindirhd)) {
+				aip->ai_state |= DEPCOMPLETE;
+				aip->ai_buf = NULL;
+				LIST_REMOVE(aip, ai_deps);
+				handle_allocindir_partdone(aip);
+			}
+			while ((inodedep =
+			       LIST_FIRST(&bmsafemap->sm_inodedephd)) != NULL) {
+				inodedep->id_state |= DEPCOMPLETE;
+				LIST_REMOVE(inodedep, id_deps);
+				inodedep->id_buf = NULL;
+			}
+			WORKITEM_FREE(bmsafemap, M_BMSAFEMAP);
+			continue;
+
+		case M_MKDIR:
+			handle_written_mkdir(WK_MKDIR(wk), MKDIR_BODY);
+			continue;
+
+		case M_ALLOCDIRECT:
+			adp = WK_ALLOCDIRECT(wk);
+			adp->ad_state |= COMPLETE;
+			handle_allocdirect_partdone(adp);
+			continue;
+
+		case M_ALLOCINDIR:
+			aip = WK_ALLOCINDIR(wk);
+			aip->ai_state |= COMPLETE;
+			handle_allocindir_partdone(aip);
+			continue;
+
+		case M_INDIRDEP:
+			indirdep = WK_INDIRDEP(wk);
+			if (indirdep->ir_state & GOINGAWAY)
+				panic("disk_write_complete: indirdep gone");
+			bp->b_data = (caddr_t)indirdep->ir_saveddata;
+			indirdep->ir_state &= ~UNDONE;
+			indirdep->ir_state |= ATTACHED;
+			while ((aip = LIST_FIRST(&indirdep->ir_donehd)) != 0) {
+				LIST_REMOVE(aip, ai_next);
+				handle_allocindir_partdone(aip);
+			}
+			WORKLIST_INSERT(&reattach, wk);
+			bdirty(bp);
+			continue;
+
+		default:
+			panic("handle_disk_write_complete: Unknown type %s",
+			    TYPENAME(wk->wk_type));
+			/* NOTREACHED */
+		}
+	}
+	/*
+	 * Reattach any requests that must be redone.
+	 */
+	while ((wk = LIST_FIRST(&reattach)) != NULL) {
+		WORKLIST_REMOVE(wk);
+		WORKLIST_INSERT(&bp->b_dep, wk);
+	}
+#ifdef DEBUG
+	if (lk.lkt_held != -2)
+		panic("softdep_disk_write_complete: lock lost");
+	lk.lkt_held = -1;
+#endif
+}
+
+/*
+ * Called from within softdep_disk_write_complete above. Note that
+ * this routine is always called from interrupt level with further
+ * splbio interrupts blocked.
+ */
+static void 
+handle_allocdirect_partdone(adp)
+	struct allocdirect *adp;	/* the completed allocdirect */
+{
+	struct allocdirect *listadp;
+	struct inodedep *inodedep;
+	long bsize;
+
+	if ((adp->ad_state & ALLCOMPLETE) != ALLCOMPLETE)
+		return;
+	if (adp->ad_buf != NULL)
+		panic("handle_allocdirect_partdone: dangling dep");
+	/*
+	 * The on-disk inode cannot claim to be any larger than the last
+	 * fragment that has been written. Otherwise, the on-disk inode
+	 * might have fragments that were not the last block in the file
+	 * which would corrupt the filesystem. Thus, we cannot free any
+	 * allocdirects after one whose ad_oldblkno claims a fragment as
+	 * these blocks must be rolled back to zero before writing the inode.
+	 * We check the currently active set of allocdirects in id_inoupdt.
+	 */
+	inodedep = adp->ad_inodedep;
+	bsize = inodedep->id_fs->fs_bsize;
+	for (listadp = TAILQ_FIRST(&inodedep->id_inoupdt); listadp;
+	     listadp = TAILQ_NEXT(listadp, ad_next)) {
+		/* found our block */
+		if (listadp == adp)
+			break;
+		/* continue if ad_oldlbn is not a fragment */
+		if (listadp->ad_oldsize == 0 ||
+		    listadp->ad_oldsize == bsize)
+			continue;
+		/* hit a fragment */
+		return;
+	}
+	/*
+	 * If we have reached the end of the current list without
+	 * finding the just finished dependency, then it must be
+	 * on the future dependency list. Future dependencies cannot
+	 * be freed until they are moved to the current list.
+	 */
+	if (listadp == NULL) {
+#ifdef DEBUG
+		for (listadp = TAILQ_FIRST(&inodedep->id_newinoupdt); listadp;
+		     listadp = TAILQ_NEXT(listadp, ad_next))
+			/* found our block */
+			if (listadp == adp)
+				break;
+		if (listadp == NULL)
+			panic("handle_allocdirect_partdone: lost dep");
+#endif /* DEBUG */
+		return;
+	}
+	/*
+	 * If we have found the just finished dependency, then free
+	 * it along with anything that follows it that is complete.
+	 */
+	for (; adp; adp = listadp) {
+		listadp = TAILQ_NEXT(adp, ad_next);
+		if ((adp->ad_state & ALLCOMPLETE) != ALLCOMPLETE)
+			return;
+		free_allocdirect(&inodedep->id_inoupdt, adp, 1);
+	}
+	/*
+	 * Try freeing the inodedep in case that was the last dependency.
+	 */
+	(void) free_inodedep(inodedep);
+}
+
+/*
+ * Called from within softdep_disk_write_complete above. Note that
+ * this routine is always called from interrupt level with further
+ * splbio interrupts blocked.
+ */
+static void
+handle_allocindir_partdone(aip)
+	struct allocindir *aip;		/* the completed allocindir */
+{
+	struct indirdep *indirdep;
+
+	if ((aip->ai_state & ALLCOMPLETE) != ALLCOMPLETE)
+		return;
+	if (aip->ai_buf != NULL)
+		panic("handle_allocindir_partdone: dangling dependency");
+	indirdep = aip->ai_indirdep;
+	if (indirdep->ir_state & UNDONE) {
+		LIST_REMOVE(aip, ai_next);
+		LIST_INSERT_HEAD(&indirdep->ir_donehd, aip, ai_next);
+		return;
+	}
+	((ufs_daddr_t *)indirdep->ir_savebp->b_data)[aip->ai_offset] =
+	    aip->ai_newblkno;
+	LIST_REMOVE(aip, ai_next);
+	if (aip->ai_freefrag != NULL)
+		add_to_worklist(&aip->ai_freefrag->ff_list);
+	WORKITEM_FREE(aip, M_ALLOCINDIR);
+}
+
+/*
+ * Called from within softdep_disk_write_complete above to restore
+ * in-memory inode block contents to their most up-to-date state. Note
+ * that this routine is always called from interrupt level with further
+ * splbio interrupts blocked.
+ */
+static int 
+handle_written_inodeblock(inodedep, bp)
+	struct inodedep *inodedep;
+	struct buf *bp;		/* buffer containing the inode block */
+{
+	struct pagedep *pagedep;
+	struct worklist *wk, *filefree;
+	struct allocdirect *adp, *nextadp;
+	struct dinode *dp;
+	struct diradd *dap;
+	int hadchanges;
+
+	if ((inodedep->id_state & IOSTARTED) == 0)
+		panic("handle_written_inodeblock: not started");
+	inodedep->id_state &= ~IOSTARTED;
+	inodedep->id_state |= COMPLETE;
+	dp = (struct dinode *)bp->b_data +
+	    ino_to_fsbo(inodedep->id_fs, inodedep->id_ino);
+	/*
+	 * If we had to rollback the inode allocation because of
+	 * bitmaps being incomplete, then simply restore it.
+	 * Keep the block dirty so that it will not be reclaimed until
+	 * all associated dependencies have been cleared and the
+	 * corresponding updates written to disk.
+	 */
+	if (inodedep->id_savedino != NULL) {
+		*dp = *inodedep->id_savedino;
+		FREE(inodedep->id_savedino, M_INODEDEP);
+		inodedep->id_savedino = NULL;
+		bdirty(bp);
+		return (1);
+	}
+	/*
+	 * Roll forward anything that had to be rolled back before 
+	 * the inode could be updated.
+	 */
+	hadchanges = 0;
+	for (adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp; adp = nextadp) {
+		nextadp = TAILQ_NEXT(adp, ad_next);
+		if (adp->ad_state & ATTACHED)
+			panic("handle_written_inodeblock: new entry");
+		if (adp->ad_lbn < NDADDR) {
+			if (dp->di_db[adp->ad_lbn] != adp->ad_oldblkno)
+				panic("%s: %s #%d mismatch %d != %d",
+				    "handle_written_inodeblock",
+				    "direct pointer", adp->ad_lbn,
+				    dp->di_db[adp->ad_lbn], adp->ad_oldblkno);
+			dp->di_db[adp->ad_lbn] = adp->ad_newblkno;
+		} else {
+			if (dp->di_ib[adp->ad_lbn - NDADDR] != 0)
+				panic("%s: %s #%d allocated as %d",
+				    "handle_written_inodeblock",
+				    "indirect pointer", adp->ad_lbn - NDADDR,
+				    dp->di_ib[adp->ad_lbn - NDADDR]);
+			dp->di_ib[adp->ad_lbn - NDADDR] = adp->ad_newblkno;
+		}
+		adp->ad_state &= ~UNDONE;
+		adp->ad_state |= ATTACHED;
+		hadchanges = 1;
+	}
+	/*
+	 * Reset the file size to its most up-to-date value.
+	 */
+	if (inodedep->id_savedsize == -1)
+		panic("handle_written_inodeblock: bad size");
+	if (dp->di_size != inodedep->id_savedsize) {
+		dp->di_size = inodedep->id_savedsize;
+		hadchanges = 1;
+	}
+	inodedep->id_savedsize = -1;
+	/*
+	 * If there were any rollbacks in the inode block, then it must be
+	 * marked dirty so that its will eventually get written back in
+	 * its correct form.
+	 */
+	if (hadchanges)
+		bdirty(bp);
+	/*
+	 * Process any allocdirects that completed during the update.
+	 */
+	if ((adp = TAILQ_FIRST(&inodedep->id_inoupdt)) != NULL)
+		handle_allocdirect_partdone(adp);
+	/*
+	 * Process deallocations that were held pending until the
+	 * inode had been written to disk. Freeing of the inode
+	 * is delayed until after all blocks have been freed to
+	 * avoid creation of new <vfsid, inum, lbn> triples
+	 * before the old ones have been deleted.
+	 */
+	filefree = NULL;
+	while ((wk = LIST_FIRST(&inodedep->id_inowait)) != NULL) {
+		WORKLIST_REMOVE(wk);
+		switch (wk->wk_type) {
+
+		case M_FREEFILE:
+			/*
+			 * We defer adding filefree to the worklist until
+			 * all other additions have been made to ensure
+			 * that it will be done after all the old blocks
+			 * have been freed.
+			 */
+			if (filefree != NULL)
+				panic("handle_written_inodeblock: filefree");
+			filefree = wk;
+			continue;
+
+		case M_MKDIR:
+			handle_written_mkdir(WK_MKDIR(wk), MKDIR_PARENT);
+			continue;
+
+		case M_DIRADD:
+			dap = WK_DIRADD(wk);
+			dap->da_state |= COMPLETE;
+			if ((dap->da_state & ALLCOMPLETE) == ALLCOMPLETE) {
+				if (dap->da_state & DIRCHG)
+					pagedep = dap->da_previous->dm_pagedep;
+				else
+					pagedep = dap->da_pagedep;
+				LIST_REMOVE(dap, da_pdlist);
+				LIST_INSERT_HEAD(&pagedep->pd_pendinghd, dap,
+				    da_pdlist);
+			}
+			WORKLIST_INSERT(&inodedep->id_pendinghd, wk);
+			continue;
+
+		case M_FREEBLKS:
+		case M_FREEFRAG:
+		case M_DIRREM:
+			add_to_worklist(wk);
+			continue;
+
+		default:
+			panic("handle_written_inodeblock: Unknown type %s",
+			    TYPENAME(wk->wk_type));
+			/* NOTREACHED */
+		}
+	}
+	if (filefree != NULL)
+		add_to_worklist(filefree);
+
+	/*
+	 * If no outstanding dependencies, free it.
+	 */
+	if (free_inodedep(inodedep) || TAILQ_FIRST(&inodedep->id_inoupdt) == 0)
+		return (0);
+	return (hadchanges);
+}
+
+/*
+ * Handle the completion of a mkdir dependency.
+ */
+static void
+handle_written_mkdir(mkdir, type)
+	struct mkdir *mkdir;
+	int type;
+{
+	struct diradd *dap;
+	struct pagedep *pagedep;
+
+	if (mkdir->md_state != type)
+		panic("handle_written_mkdir: bad type");
+	dap = mkdir->md_diradd;
+	dap->da_state &= ~type;
+	if ((dap->da_state & (MKDIR_PARENT | MKDIR_BODY)) == 0)
+		dap->da_state |= DEPCOMPLETE;
+	if ((dap->da_state & ALLCOMPLETE) == ALLCOMPLETE) {
+		if (dap->da_state & DIRCHG)
+			pagedep = dap->da_previous->dm_pagedep;
+		else
+			pagedep = dap->da_pagedep;
+		LIST_REMOVE(dap, da_pdlist);
+		LIST_INSERT_HEAD(&pagedep->pd_pendinghd, dap, da_pdlist);
+	}
+	LIST_REMOVE(mkdir, md_mkdirs);
+	WORKITEM_FREE(mkdir, M_MKDIR);
+}
+
+/*
+ * Called from within softdep_disk_write_complete above.
+ * A write operation was just completed. Removed inodes can
+ * now be freed and associated block pointers may be committed.
+ * Note that this routine is always called from interrupt level
+ * with further splbio interrupts blocked.
+ */
+static int 
+handle_written_filepage(pagedep, bp)
+	struct pagedep *pagedep;
+	struct buf *bp;		/* buffer containing the written page */
+{
+	struct dirrem *dirrem;
+	struct diradd *dap, *nextdap;
+	struct direct *ep;
+	int i, chgs;
+
+	if ((pagedep->pd_state & IOSTARTED) == 0)
+		panic("handle_written_filepage: not started");
+	pagedep->pd_state &= ~IOSTARTED;
+	/*
+	 * Process any directory removals that have been committed.
+	 */
+	while ((dirrem = LIST_FIRST(&pagedep->pd_dirremhd)) != NULL) {
+		LIST_REMOVE(dirrem, dm_next);
+		dirrem->dm_dirinum = pagedep->pd_ino;
+		add_to_worklist(&dirrem->dm_list);
+	}
+	/*
+	 * Free any directory additions that have been committed.
+	 */
+	while ((dap = LIST_FIRST(&pagedep->pd_pendinghd)) != NULL)
+		free_diradd(dap);
+	/*
+	 * Uncommitted directory entries must be restored.
+	 */
+	for (chgs = 0, i = 0; i < DAHASHSZ; i++) {
+		for (dap = LIST_FIRST(&pagedep->pd_diraddhd[i]); dap;
+		     dap = nextdap) {
+			nextdap = LIST_NEXT(dap, da_pdlist);
+			if (dap->da_state & ATTACHED)
+				panic("handle_written_filepage: attached");
+			ep = (struct direct *)
+			    ((char *)bp->b_data + dap->da_offset);
+			ep->d_ino = dap->da_newinum;
+			dap->da_state &= ~UNDONE;
+			dap->da_state |= ATTACHED;
+			chgs = 1;
+			/*
+			 * If the inode referenced by the directory has
+			 * been written out, then the dependency can be
+			 * moved to the pending list.
+			 */
+			if ((dap->da_state & ALLCOMPLETE) == ALLCOMPLETE) {
+				LIST_REMOVE(dap, da_pdlist);
+				LIST_INSERT_HEAD(&pagedep->pd_pendinghd, dap,
+				    da_pdlist);
+			}
+		}
+	}
+	/*
+	 * If there were any rollbacks in the directory, then it must be
+	 * marked dirty so that its will eventually get written back in
+	 * its correct form.
+	 */
+	if (chgs)
+		bdirty(bp);
+	/*
+	 * If no dependencies remain, the pagedep will be freed.
+	 * Otherwise it will remain to update the page before it
+	 * is written back to disk.
+	 */
+	if (LIST_FIRST(&pagedep->pd_dirremhd) == 0 &&
+	    LIST_FIRST(&pagedep->pd_pendinghd) == 0) {
+		for (i = 0; i < DAHASHSZ; i++)
+			if (LIST_FIRST(&pagedep->pd_diraddhd[i]) != NULL)
+				break;
+		if (i == DAHASHSZ) {
+			LIST_REMOVE(pagedep, pd_hash);
+			WORKITEM_FREE(pagedep, M_PAGEDEP);
+			return (0);
+		}
+	}
+	return (1);
+}
+
+/*
+ * Writing back in-core inode structures.
+ * 
+ * The file system only accesses an inode's contents when it occupies an
+ * "in-core" inode structure.  These "in-core" structures are separate from
+ * the page frames used to cache inode blocks.  Only the latter are
+ * transferred to/from the disk.  So, when the updated contents of the
+ * "in-core" inode structure are copied to the corresponding in-memory inode
+ * block, the dependencies are also transferred.  The following procedure is
+ * called when copying a dirty "in-core" inode to a cached inode block.
+ */
+
+/*
+ * Called when an inode is loaded from disk. If the effective link count
+ * differed from the actual link count when it was last flushed, then we
+ * need to ensure that the correct effective link count is put back.
+ */
+void 
+softdep_load_inodeblock(ip)
+	struct inode *ip;	/* the "in_core" copy of the inode */
+{
+	struct inodedep *inodedep;
+	int error, gotit;
+
+	/*
+	 * Check for alternate nlink count.
+	 */
+	ip->i_effnlink = ip->i_nlink;
+	ACQUIRE_LOCK(&lk);
+	if (inodedep_lookup(ip->i_fs, ip->i_number, 0, &inodedep) == 0) {
+		FREE_LOCK(&lk);
+		return;
+	}
+	if (inodedep->id_nlinkdelta != 0) {
+		ip->i_effnlink -= inodedep->id_nlinkdelta;
+		inodedep->id_nlinkdelta = 0;
+		(void) free_inodedep(inodedep);
+	}
+	FREE_LOCK(&lk);
+}
+
+/*
+ * This routine is called just before the "in-core" inode
+ * information is to be copied to the in-memory inode block.
+ * Recall that an inode block contains several inodes. If
+ * the force flag is set, then the dependencies will be
+ * cleared so that the update can always be made. Note that
+ * the buffer is locked when this routine is called, so we
+ * will never be in the middle of writing the inode block 
+ * to disk.
+ */
+void 
+softdep_update_inodeblock(ip, bp, waitfor)
+	struct inode *ip;	/* the "in_core" copy of the inode */
+	struct buf *bp;		/* the buffer containing the inode block */
+	int waitfor;		/* 1 => update must be allowed */
+{
+	struct inodedep *inodedep;
+	int error, gotit;
+
+	/*
+	 * If the effective link count is not equal to the actual link
+	 * count, then we must track the difference in an inodedep while
+	 * the inode is (potentially) tossed out of the cache. Otherwise,
+	 * if there is no existing inodedep, then there are no dependencies
+	 * to track.
+	 */
+	ACQUIRE_LOCK(&lk);
+	if (ip->i_effnlink != ip->i_nlink) {
+		(void) inodedep_lookup(ip->i_fs, ip->i_number, DEPALLOC,
+		    &inodedep);
+	} else if (inodedep_lookup(ip->i_fs, ip->i_number, 0, &inodedep) == 0) {
+		FREE_LOCK(&lk);
+		return;
+	}
+	if (ip->i_nlink < ip->i_effnlink)
+		panic("softdep_update_inodeblock: bad delta");
+	inodedep->id_nlinkdelta = ip->i_nlink - ip->i_effnlink;
+	/*
+	 * If the last remaining use for the inodedep was to track the
+	 * link count, and there is no difference between the effective
+	 * and actual link count, then we can free the inodedep.
+	 */
+	if (free_inodedep(inodedep)) {
+		FREE_LOCK(&lk);
+		return;
+	}
+	/*
+	 * Changes have been initiated. Anything depending on these
+	 * changes cannot occur until this inode has been written.
+	 */
+	inodedep->id_state &= ~COMPLETE;
+	if ((inodedep->id_state & ONWORKLIST) == 0)
+		WORKLIST_INSERT(&bp->b_dep, &inodedep->id_list);
+	/*
+	 * Any new dependencies associated with the incore inode must 
+	 * now be moved to the list associated with the buffer holding
+	 * the in-memory copy of the inode. Once merged process any
+	 * allocdirects that are completed by the merger.
+	 */
+	merge_inode_lists(inodedep);
+	if (TAILQ_FIRST(&inodedep->id_inoupdt) != NULL)
+		handle_allocdirect_partdone(TAILQ_FIRST(&inodedep->id_inoupdt));
+	/*
+	 * Newly allocated inodes cannot be written until the bitmap
+	 * that allocates them have been written (indicated by
+	 * DEPCOMPLETE being set in id_state). If we are doing a
+	 * forced sync (e.g., an fsync on a file), we force the bitmap
+	 * to be written so that the update can be done.
+	 */
+	if ((inodedep->id_state & DEPCOMPLETE) != 0 || waitfor == 0) {
+		FREE_LOCK(&lk);
+		return;
+	}
+	gotit = getdirtybuf(&inodedep->id_buf, MNT_WAIT);
+	FREE_LOCK(&lk);
+	if (gotit && (error = VOP_BWRITE(inodedep->id_buf)) != 0)
+		softdep_error("softdep_update_inodeblock: bwrite", error);
+	if ((inodedep->id_state & DEPCOMPLETE) == 0)
+		panic("softdep_update_inodeblock: update failed");
+}
+
+/*
+ * Merge the new inode dependency list (id_newinoupdt) into the old
+ * inode dependency list (id_inoupdt). This routine must be called
+ * with splbio interrupts blocked.
+ */
+static void
+merge_inode_lists(inodedep)
+	struct inodedep *inodedep;
+{
+	struct allocdirect *listadp, *newadp;
+
+	newadp = TAILQ_FIRST(&inodedep->id_newinoupdt);
+	for (listadp = TAILQ_FIRST(&inodedep->id_inoupdt); listadp && newadp;) {
+		if (listadp->ad_lbn < newadp->ad_lbn) {
+			listadp = TAILQ_NEXT(listadp, ad_next);
+			continue;
+		}
+		TAILQ_REMOVE(&inodedep->id_newinoupdt, newadp, ad_next);
+		TAILQ_INSERT_BEFORE(listadp, newadp, ad_next);
+		if (listadp->ad_lbn == newadp->ad_lbn) {
+			allocdirect_merge(&inodedep->id_inoupdt, newadp,
+			    listadp);
+			listadp = newadp;
+		}
+		newadp = TAILQ_FIRST(&inodedep->id_newinoupdt);
+	}
+	while ((newadp = TAILQ_FIRST(&inodedep->id_newinoupdt)) != NULL) {
+		TAILQ_REMOVE(&inodedep->id_newinoupdt, newadp, ad_next);
+		TAILQ_INSERT_TAIL(&inodedep->id_inoupdt, newadp, ad_next);
+	}
+}
+
+/*
+ * If we are doing an fsync, then we must ensure that any directory
+ * entries for the inode have been written after the inode gets to disk.
+ */
+int
+softdep_fsync(vp)
+	struct vnode *vp;	/* the "in_core" copy of the inode */
+{
+	struct diradd *dap, *olddap;
+	struct inodedep *inodedep;
+	struct pagedep *pagedep;
+	struct worklist *wk;
+	struct mount *mnt;
+	struct vnode *pvp;
+	struct inode *ip;
+	struct buf *bp;
+	struct fs *fs;
+	struct proc *p = curproc;		/* XXX */
+	int error, ret, flushparent;
+	struct timeval tv;
+	ino_t parentino;
+	ufs_lbn_t lbn;
+
+	ip = VTOI(vp);
+	fs = ip->i_fs;
+	for (error = 0, flushparent = 0, olddap = NULL; ; ) {
+		ACQUIRE_LOCK(&lk);
+		if (inodedep_lookup(fs, ip->i_number, 0, &inodedep) == 0)
+			break;
+		if (LIST_FIRST(&inodedep->id_inowait) != NULL ||
+		    TAILQ_FIRST(&inodedep->id_inoupdt) != NULL ||
+		    TAILQ_FIRST(&inodedep->id_newinoupdt) != NULL)
+			panic("softdep_fsync: pending ops");
+		if ((wk = LIST_FIRST(&inodedep->id_pendinghd)) == NULL)
+			break;
+		if (wk->wk_type != M_DIRADD)
+			panic("softdep_fsync: Unexpcted type %s",
+			    TYPENAME(wk->wk_type));
+		dap = WK_DIRADD(wk);
+		/*
+		 * If we have failed to get rid of all the dependencies
+		 * then something is seriously wrong.
+		 */
+		if (dap == olddap)
+			panic("softdep_fsync: flush failed");
+		olddap = dap;
+		/*
+		 * Flush our parent if this directory entry
+		 * has a MKDIR_PARENT dependency.
+		 */
+		if (dap->da_state & DIRCHG)
+			pagedep = dap->da_previous->dm_pagedep;
+		else
+			pagedep = dap->da_pagedep;
+		mnt = pagedep->pd_mnt;
+		parentino = pagedep->pd_ino;
+		lbn = pagedep->pd_lbn;
+		if ((dap->da_state & (MKDIR_BODY | COMPLETE)) != COMPLETE)
+			panic("softdep_fsync: dirty");
+		flushparent = dap->da_state & MKDIR_PARENT;
+		/*
+		 * If we are being fsync'ed as part of vgone'ing this vnode,
+		 * then we will not be able to release and recover the
+		 * vnode below, so we just have to give up on writing its
+		 * directory entry out. It will eventually be written, just
+		 * not now, but then the user was not asking to have it
+		 * written, so we are not breaking any promises.
+		 */
+		if (vp->v_flag & VXLOCK)
+			break;
+		/*
+		 * We prevent deadlock by always fetching inodes from the
+		 * root, moving down the directory tree. Thus, when fetching
+		 * our parent directory, we must unlock ourselves before
+		 * requesting the lock on our parent. See the comment in
+		 * ufs_lookup for details on possible races.
+		 */
+		FREE_LOCK(&lk);
+		VOP_UNLOCK(vp, 0, p);
+		if ((error = VFS_VGET(mnt, parentino, &pvp)) != 0) {
+			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
+			return (error);
+		}
+		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
+		if (flushparent) {
+			tv = time;
+			if (error = VOP_UPDATE(pvp, &tv, &tv, MNT_WAIT)) {
+				vput(pvp);
+				return (error);
+			}
+		}
+		/*
+		 * Flush directory page containing the inode's name.
+		 */
+		error = bread(pvp, lbn, blksize(fs, VTOI(pvp), lbn), p->p_ucred,
+		    &bp);
+		vput(pvp);
+		ret = VOP_BWRITE(bp);
+		if (error != 0)
+			return (error);
+		if (ret != 0)
+			return (ret);
+	}
+	FREE_LOCK(&lk);
+	return (0);
+}
+
+/*
+ * This routine is called when we are trying to synchronously flush a
+ * file. This routine must eliminate any filesystem metadata dependencies
+ * so that the syncing routine can succeed by pushing the dirty blocks
+ * associated with the file. If any I/O errors occur, they are returned.
+ */
+int
+softdep_sync_metadata(ap)
+	struct vop_fsync_args /* {
+		struct vnode *a_vp;
+		struct ucred *a_cred;
+		int a_waitfor;
+		struct proc *a_p;
+	} */ *ap;
+{
+	struct vnode *vp = ap->a_vp;
+	struct allocdirect *adp;
+	struct allocindir *aip;
+	struct buf *bp, *nbp;
+	struct worklist *wk;
+	int error, waitfor;
+
+	/*
+	 * Check whether this vnode is involved in a filesystem
+	 * that is doing soft dependency processing.
+	 */
+	if (vp->v_type != VBLK) {
+		if (!DOINGSOFTDEP(vp))
+			return (0);
+	} else
+		if (vp->v_specmountpoint == NULL ||
+		    (vp->v_specmountpoint->mnt_flag & MNT_SOFTDEP) == 0)
+			return (0);
+	/*
+	 * Ensure that any direct block dependencies have been cleared.
+	 */
+	ACQUIRE_LOCK(&lk);
+	if (error = flush_inodedep_deps(VTOI(vp)->i_fs, VTOI(vp)->i_number)) {
+		FREE_LOCK(&lk);
+		return (error);
+	}
+	/*
+	 * For most files, the only metadata dependencies are the
+	 * cylinder group maps that allocate their inode or blocks.
+	 * The block allocation dependencies can be found by traversing
+	 * the dependency lists for any buffers that remain on their
+	 * dirty buffer list. The inode allocation dependency will
+	 * be resolved when the inode is updated with MNT_WAIT.
+	 * This work is done in two passes. The first pass grabs most
+	 * of the buffers and begins asynchronously writing them. The
+	 * only way to wait for these asynchronous writes is to sleep
+	 * on the filesystem vnode which may stay busy for a long time
+	 * if the filesystem is active. So, instead, we make a second
+	 * pass over the dependencies blocking on each write. In the
+	 * usual case we will be blocking against a write that we
+	 * initiated, so when it is done the dependency will have been
+	 * resolved. Thus the second pass is expected to end quickly.
+	 */
+	waitfor = MNT_NOWAIT;
+top:
+	if (getdirtybuf(&LIST_FIRST(&vp->v_dirtyblkhd), MNT_WAIT) == 0) {
+		FREE_LOCK(&lk);
+		return (0);
+	}
+	bp = LIST_FIRST(&vp->v_dirtyblkhd);
+loop:
+	/*
+	 * As we hold the buffer locked, none of its dependencies
+	 * will disappear.
+	 */
+	for (wk = LIST_FIRST(&bp->b_dep); wk;
+	     wk = LIST_NEXT(wk, wk_list)) {
+		switch (wk->wk_type) {
+
+		case M_ALLOCDIRECT:
+			adp = WK_ALLOCDIRECT(wk);
+			if (adp->ad_state & DEPCOMPLETE)
+				break;
+			nbp = adp->ad_buf;
+			if (getdirtybuf(&nbp, waitfor) == 0)
+				break;
+			FREE_LOCK(&lk);
+			if (waitfor == MNT_NOWAIT) {
+				bawrite(nbp);
+			} else if ((error = VOP_BWRITE(nbp)) != 0) {
+				bawrite(bp);
+				return (error);
+			}
+			ACQUIRE_LOCK(&lk);
+			break;
+
+		case M_ALLOCINDIR:
+			aip = WK_ALLOCINDIR(wk);
+			if (aip->ai_state & DEPCOMPLETE)
+				break;
+			nbp = aip->ai_buf;
+			if (getdirtybuf(&nbp, waitfor) == 0)
+				break;
+			FREE_LOCK(&lk);
+			if (waitfor == MNT_NOWAIT) {
+				bawrite(nbp);
+			} else if ((error = VOP_BWRITE(nbp)) != 0) {
+				bawrite(bp);
+				return (error);
+			}
+			ACQUIRE_LOCK(&lk);
+			break;
+
+		case M_INDIRDEP:
+			for (aip = LIST_FIRST(&WK_INDIRDEP(wk)->ir_deplisthd);
+			     aip; aip = LIST_NEXT(aip, ai_next)) {
+				if (aip->ai_state & DEPCOMPLETE)
+					continue;
+				nbp = aip->ai_buf;
+				if (getdirtybuf(&nbp, waitfor) == 0)
+					break;
+				FREE_LOCK(&lk);
+				if (waitfor == MNT_NOWAIT) {
+					bawrite(nbp);
+				} else if ((error = VOP_BWRITE(nbp)) != 0) {
+					bawrite(bp);
+					return (error);
+				}
+				ACQUIRE_LOCK(&lk);
+				continue;
+			}
+			break;
+
+		case M_INODEDEP:
+			if ((error = flush_inodedep_deps(WK_INODEDEP(wk)->id_fs,
+			    WK_INODEDEP(wk)->id_ino)) != 0) {
+				FREE_LOCK(&lk);
+				bawrite(bp);
+				return (error);
+			}
+			break;
+
+		case M_PAGEDEP:
+			/*
+			 * We are trying to sync a directory that may
+			 * have dependencies on both its own metadata
+			 * and/or dependencies on the inodes of any
+			 * recently allocated files. We walk its diradd
+			 * lists pushing out the associated inode.
+			 */
+			if (error = flush_pagedep_deps(vp, WK_PAGEDEP(wk))) {
+				FREE_LOCK(&lk);
+				bawrite(bp);
+				return (error);
+			}
+			break;
+
+		default:
+			panic("softdep_sync_metadata: Unknown type %s",
+			    TYPENAME(wk->wk_type));
+			/* NOTREACHED */
+		}
+	}
+	(void) getdirtybuf(&LIST_NEXT(bp, b_vnbufs), MNT_WAIT);
+	nbp = LIST_NEXT(bp, b_vnbufs);
+	FREE_LOCK(&lk);
+	bawrite(bp);
+	ACQUIRE_LOCK(&lk);
+	if (nbp != NULL) {
+		bp = nbp;
+		goto loop;
+	}
+	/*
+	 * We must wait for any I/O in progress to finish so that
+	 * all potential buffers on the dirty list will be visible.
+	 * Once they are all there, proceed with the second pass
+	 * which will wait for the I/O as per above.
+	 */
+	while (vp->v_numoutput) {
+		vp->v_flag |= VBWAIT;
+		FREE_LOCK_INTERLOCKED(&lk);
+		sleep((caddr_t)&vp->v_numoutput, PRIBIO + 1);
+		ACQUIRE_LOCK_INTERLOCKED(&lk);
+	}
+	/*
+	 * The brief unlock is to allow any pent up dependency
+	 * processing to be done.
+	 */
+	if (waitfor == MNT_NOWAIT) {
+		waitfor = MNT_WAIT;
+		FREE_LOCK(&lk);
+		ACQUIRE_LOCK(&lk);
+		goto top;
+	}
+
+	/*
+	 * If we have managed to get rid of all the dirty buffers,
+	 * then we are done. For certain directories and block
+	 * devices, we may need to do further work.
+	 */
+	if (LIST_FIRST(&vp->v_dirtyblkhd) == NULL) {
+		FREE_LOCK(&lk);
+		return (0);
+	}
+
+	FREE_LOCK(&lk);
+	/*
+	 * If we are trying to sync a block device, some of its buffers may
+	 * contain metadata that cannot be written until the contents of some
+	 * partially written files have been written to disk. The only easy
+	 * way to accomplish this is to sync the entire filesystem (luckily
+	 * this happens rarely).
+	 */
+	if (vp->v_type == VBLK && vp->v_specmountpoint && !VOP_ISLOCKED(vp) &&
+	    (error = VFS_SYNC(vp->v_specmountpoint, MNT_WAIT, ap->a_cred,
+	     ap->a_p)) != 0)
+		return (error);
+	return (0);
+}
+
+/*
+ * Flush the dependencies associated with an inodedep.
+ * Called with splbio blocked.
+ */
+static int
+flush_inodedep_deps(fs, ino)
+	struct fs *fs;
+	ino_t ino;
+{
+	struct inodedep *inodedep;
+	struct allocdirect *adp;
+	int error, waitfor;
+	struct buf *bp;
+
+	/*
+	 * This work is done in two passes. The first pass grabs most
+	 * of the buffers and begins asynchronously writing them. The
+	 * only way to wait for these asynchronous writes is to sleep
+	 * on the filesystem vnode which may stay busy for a long time
+	 * if the filesystem is active. So, instead, we make a second
+	 * pass over the dependencies blocking on each write. In the
+	 * usual case we will be blocking against a write that we
+	 * initiated, so when it is done the dependency will have been
+	 * resolved. Thus the second pass is expected to end quickly.
+	 * We give a brief window at the top of the loop to allow
+	 * any pending I/O to complete.
+	 */
+	for (waitfor = MNT_NOWAIT; ; ) {
+		FREE_LOCK(&lk);
+		ACQUIRE_LOCK(&lk);
+		if (inodedep_lookup(fs, ino, 0, &inodedep) == 0)
+			return (0);
+		for (adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp;
+		     adp = TAILQ_NEXT(adp, ad_next)) {
+			if (adp->ad_state & DEPCOMPLETE)
+				continue;
+			bp = adp->ad_buf;
+			if (getdirtybuf(&bp, waitfor) == 0)
+				break;
+			FREE_LOCK(&lk);
+			if (waitfor == MNT_NOWAIT) {
+				bawrite(bp);
+			} else if ((error = VOP_BWRITE(bp)) != 0) {
+				ACQUIRE_LOCK(&lk);
+				return (error);
+			}
+			ACQUIRE_LOCK(&lk);
+			break;
+		}
+		if (adp != NULL)
+			continue;
+		for (adp = TAILQ_FIRST(&inodedep->id_newinoupdt); adp;
+		     adp = TAILQ_NEXT(adp, ad_next)) {
+			if (adp->ad_state & DEPCOMPLETE)
+				continue;
+			bp = adp->ad_buf;
+			if (getdirtybuf(&bp, waitfor) == 0)
+				break;
+			FREE_LOCK(&lk);
+			if (waitfor == MNT_NOWAIT) {
+				bawrite(bp);
+			} else if ((error = VOP_BWRITE(bp)) != 0) {
+				ACQUIRE_LOCK(&lk);
+				return (error);
+			}
+			ACQUIRE_LOCK(&lk);
+			break;
+		}
+		if (adp != NULL)
+			continue;
+		/*
+		 * If pass2, we are done, otherwise do pass 2.
+		 */
+		if (waitfor == MNT_WAIT)
+			break;
+		waitfor = MNT_WAIT;
+	}
+	/*
+	 * Try freeing inodedep in case all dependencies have been removed.
+	 */
+	if (inodedep_lookup(fs, ino, 0, &inodedep) != 0)
+		(void) free_inodedep(inodedep);
+	return (0);
+}
+
+/*
+ * Eliminate a pagedep dependency by flushing out all its diradd dependencies.
+ * Called with splbio blocked.
+ */
+static int
+flush_pagedep_deps(pvp, pagedep)
+	struct vnode *pvp;
+	struct pagedep *pagedep;
+{
+	struct proc *p = curproc;	/* XXX */
+	struct diradd *dap;
+	struct timeval tv;
+	struct vnode *vp;
+	int i, error;
+	ino_t inum;
+
+	for (i = 0, error = 0; i < DAHASHSZ && error == 0; i++) {
+		while ((dap = LIST_FIRST(&pagedep->pd_diraddhd[i])) != NULL) {
+			/*
+			 * Flush ourselves if this directory entry
+			 * has a MKDIR_PARENT dependency.
+			 */
+			if (dap->da_state & MKDIR_PARENT) {
+				tv = time;
+				FREE_LOCK(&lk);
+				if (error = VOP_UPDATE(pvp, &tv, &tv, MNT_WAIT))
+					break;
+				ACQUIRE_LOCK(&lk);
+				/*
+				 * If that cleared dependencies, go on to next.
+				 */
+				if (dap != LIST_FIRST(&pagedep->pd_diraddhd[i]))
+					continue;
+				if (dap->da_state & MKDIR_PARENT)
+					panic("flush_pagedep_deps: MKDIR");
+			}
+			/*
+			 * Flush the file on which the directory entry depends.
+			 */
+			inum = dap->da_newinum;
+			FREE_LOCK(&lk);
+			if ((error = VFS_VGET(pagedep->pd_mnt, inum, &vp)) != 0)
+				break;
+			if (vp->v_type == VDIR) {
+				/*
+				 * A newly allocated directory must have its
+				 * "." and ".." entries written out before its
+				 * name can be committed in its parent. We do
+				 * not want or need the full semantics of a
+				 * synchronous VOP_FSYNC as that may end up
+				 * here again, once for each directory level in
+				 * the filesystem. Instead, we push the blocks
+				 * and wait for them to clear.
+				 */
+				if (error =
+				    VOP_FSYNC(vp, p->p_cred, MNT_NOWAIT, p)) {
+					vput(vp);
+					break;
+				}
+				ACQUIRE_LOCK(&lk);
+				while (vp->v_numoutput) {
+					vp->v_flag |= VBWAIT;
+					FREE_LOCK_INTERLOCKED(&lk);
+					sleep((caddr_t)&vp->v_numoutput,
+					    PRIBIO + 1);
+					ACQUIRE_LOCK_INTERLOCKED(&lk);
+				}
+				FREE_LOCK(&lk);
+			}
+			tv = time;
+			error = VOP_UPDATE(vp, &tv, &tv, MNT_WAIT);
+			vput(vp);
+			if (error)
+				break;
+			/*
+			 * If we have failed to get rid of all the dependencies
+			 * then something is seriously wrong.
+			 */
+			if (dap == LIST_FIRST(&pagedep->pd_diraddhd[i]))
+				panic("flush_pagedep_deps: flush failed");
+			ACQUIRE_LOCK(&lk);
+		}
+	}
+	if (error)
+		ACQUIRE_LOCK(&lk);
+	return (error);
+}
+
+/*
+ * Acquire exclusive access to a buffer.
+ * Must be called with splbio blocked.
+ * Return 1 if buffer was acquired.
+ */
+static int
+getdirtybuf(bpp, waitfor)
+	struct buf **bpp;
+	int waitfor;
+{
+	struct buf *bp;
+
+	for (;;) {
+		if ((bp = *bpp) == NULL)
+			return (0);
+		if ((bp->b_flags & B_BUSY) == 0)
+			break;
+		if (waitfor != MNT_WAIT)
+			return (0);
+		bp->b_flags |= B_WANTED;
+		FREE_LOCK_INTERLOCKED(&lk);
+		sleep((caddr_t)bp, PRIBIO + 1);
+		ACQUIRE_LOCK_INTERLOCKED(&lk);
+	}
+	if ((bp->b_flags & B_DELWRI) == 0)
+		return (0);
+	bremfree(bp);
+	bp->b_flags |= B_BUSY;
+	return (1);
+}
+
+/*
+ * Called whenever a buffer that is being invalidated or reallocated
+ * contains dependencies. This should only happen if an I/O error has
+ * occurred. The routine is called with the buffer locked.
+ */ 
+void
+softdep_deallocate_dependencies(bp)
+	struct buf *bp;
+{
+	struct worklist *wk;
+
+	if ((bp->b_flags & B_ERROR) == 0)
+		panic("softdep_deallocate_dependencies: dangling deps");
+	softdep_error(bp->b_vp->v_mount->mnt_stat.f_mntonname, bp->b_error);
+	while ((wk = LIST_FIRST(&bp->b_dep)) != NULL) {
+		WORKLIST_REMOVE(wk);
+		switch (wk->wk_type) {
+		/*
+		 * XXX - should really clean up, but for now we will
+		 * just leak memory and not worry about it.
+		 */
+		case M_PAGEDEP: case M_INDIRDEP: case M_INODEDEP:
+#ifdef DEBUG
+			printf("Lost %s\n", TYPENAME(wk->wk_type));
+#endif
+			break;
+		default:
+			panic("softdep_deallocate_dependencies: bad type");
+		}
+	}
+}
+
+/*
+ * Function to handle asynchronous write errors in the filesystem.
+ */
+void
+softdep_error(func, error)
+	char *func;
+	int error;
+{
+
+	/* XXX should do something better! */
+	log(LOG_ERR, "%s: got error %d while accessing filesystem\n",
+	    func, error);
+}
diff --git a/sys/ufs/ffs/softdep.h b/sys/ufs/ffs/softdep.h
new file mode 100644
index 000000000000..3825bce4ce4e
--- /dev/null
+++ b/sys/ufs/ffs/softdep.h
@@ -0,0 +1,520 @@
+/*
+ * Copyright 1997 Marshall Kirk McKusick. All Rights Reserved.
+ *
+ * The soft dependency code is derived from work done by Greg Ganger
+ * at the University of Michigan.
+ *
+ * The following are the copyrights and redistribution conditions that
+ * apply to this copy of the soft dependency software. For a license
+ * to use, redistribute or sell the soft dependency software under
+ * conditions other than those described here, please contact the
+ * author at one of the following addresses:
+ *
+ *	Marshall Kirk McKusick		mckusick@mckusick.com
+ *	1614 Oxford Street		+1-510-843-9542
+ *	Berkeley, CA 94709-1608
+ *	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.
+ * 3. None of the names of McKusick, Ganger, or the University of Michigan
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * 4. Redistributions in any form must be accompanied by information on
+ *    how to obtain complete source code for any accompanying software
+ *    that uses the this software. This source code must either be included
+ *    in the distribution or be available for no more than the cost of
+ *    distribution plus a nominal fee, and must be freely redistributable
+ *    under reasonable conditions. For an executable file, complete
+ *    source code means the source code for all modules it contains.
+ *    It does not mean source code for modules or files that typically
+ *    accompany the operating system on which the executable file runs,
+ *    e.g., standard library modules or system header files.
+ *
+ * THIS SOFTWARE IS PROVIDED BY MARSHALL KIRK MCKUSICK ``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 MARSHALL KIRK MCKUSICK 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.
+ *
+ *	@(#)softdep.h	9.1 (McKusick) 7/9/97
+ */
+
+#include <sys/queue.h>
+
+/*
+ * Allocation dependencies are handled with undo/redo on the in-memory
+ * copy of the data. A particular data dependency is eliminated when
+ * it is ALLCOMPLETE: that is ATTACHED, DEPCOMPLETE, and COMPLETE.
+ * 
+ * ATTACHED means that the data is not currently being written to
+ * disk. UNDONE means that the data has been rolled back to a safe
+ * state for writing to the disk. When the I/O completes, the data is
+ * restored to its current form and the state reverts to ATTACHED.
+ * The data must be locked throughout the rollback, I/O, and roll
+ * forward so that the rolled back information is never visible to
+ * user processes. The COMPLETE flag indicates that the item has been
+ * written. For example, a dependency that requires that an inode be
+ * written will be marked COMPLETE after the inode has been written
+ * to disk. The DEPCOMPLETE flag indicates the completion of any other
+ * dependencies such as the writing of a cylinder group map has been
+ * completed. A dependency structure may be freed only when both it
+ * and its dependencies have completed and any rollbacks that are in
+ * progress have finished as indicated by the set of ALLCOMPLETE flags
+ * all being set. The two MKDIR flags indicate additional dependencies
+ * that must be done when creating a new directory. MKDIR_BODY is
+ * cleared when the directory data block containing the "." and ".."
+ * entries has been written. MKDIR_PARENT is cleared when the parent
+ * inode with the increased link count for ".." has been written. When
+ * both MKDIR flags have been cleared, the DEPCOMPLETE flag is set to
+ * indicate that the directory dependencies have been completed. The
+ * writing of the directory inode itself sets the COMPLETE flag which
+ * then allows the directory entry for the new directory to be written
+ * to disk. The RMDIR flag marks a dirrem structure as representing
+ * the removal of a directory rather than a file. When the removal
+ * dependencies are completed, additional work needs to be done
+ * (truncation of the "." and ".." entries, an additional decrement
+ * of the associated inode, and a decrement of the parent inode). The
+ * DIRCHG flag marks a diradd structure as representing the changing
+ * of an existing entry rather than the addition of a new one. When
+ * the update is complete the dirrem associated with the inode for
+ * the old name must be added to the worklist to do the necessary
+ * reference count decrement. The GOINGAWAY flag indicates that the
+ * data structure is frozen from further change until its dependencies
+ * have been completed and its resources freed after which it will be
+ * discarded. The IOSTARTED flag prevents multiple calls to the I/O
+ * start routine from doing multiple rollbacks. The ONWORKLIST flag
+ * shows whether the structure is currently linked onto a worklist.
+ */
+#define	ATTACHED	0x0001
+#define	UNDONE		0x0002
+#define	COMPLETE	0x0004
+#define	DEPCOMPLETE	0x0008
+#define MKDIR_PARENT	0x0010
+#define MKDIR_BODY	0x0020
+#define RMDIR		0x0040
+#define DIRCHG		0x0080
+#define GOINGAWAY	0x0100
+#define IOSTARTED	0x0200
+#define ONWORKLIST	0x8000
+
+#define	ALLCOMPLETE	(ATTACHED | COMPLETE | DEPCOMPLETE)
+
+/*
+ * The workitem queue.
+ * 
+ * It is sometimes useful and/or necessary to clean up certain dependencies
+ * in the background rather than during execution of an application process
+ * or interrupt service routine. To realize this, we append dependency
+ * structures corresponding to such tasks to a "workitem" queue. In a soft
+ * updates implementation, most pending workitems should not wait for more
+ * than a couple of seconds, so the filesystem syncer process awakens once
+ * per second to process the items on the queue.
+ */
+
+/* LIST_HEAD(workhead, worklist);	-- declared in buf.h */
+
+/*
+ * Each request can be linked onto a work queue through its worklist structure.
+ * To avoid the need for a pointer to the structure itself, this structure
+ * MUST be declared FIRST in each type in which it appears! If more than one
+ * worklist is needed in the structure, then a wk_data field must be added
+ * and the macros below changed to use it.
+ */
+struct worklist {
+	LIST_ENTRY(worklist)	wk_list;	/* list of work requests */
+	unsigned short		wk_type;	/* type of request */
+	unsigned short		wk_state;	/* state flags */
+};
+#define WK_DATA(wk) ((void *)(wk))
+#define WK_PAGEDEP(wk) ((struct pagedep *)(wk))
+#define WK_INODEDEP(wk) ((struct inodedep *)(wk))
+#define WK_NEWBLK(wk) ((struct newblk *)(wk))
+#define WK_BMSAFEMAP(wk) ((struct bmsafemap *)(wk))
+#define WK_ALLOCDIRECT(wk) ((struct allocdirect *)(wk))
+#define WK_INDIRDEP(wk) ((struct indirdep *)(wk))
+#define WK_ALLOCINDIR(wk) ((struct allocindir *)(wk))
+#define WK_FREEFRAG(wk) ((struct freefrag *)(wk))
+#define WK_FREEBLKS(wk) ((struct freeblks *)(wk))
+#define WK_FREEFILE(wk) ((struct freefile *)(wk))
+#define WK_DIRADD(wk) ((struct diradd *)(wk))
+#define WK_MKDIR(wk) ((struct mkdir *)(wk))
+#define WK_DIRREM(wk) ((struct dirrem *)(wk))
+
+/*
+ * Various types of lists
+ */
+LIST_HEAD(dirremhd, dirrem);
+LIST_HEAD(diraddhd, diradd);
+LIST_HEAD(newblkhd, newblk);
+LIST_HEAD(inodedephd, inodedep);
+LIST_HEAD(allocindirhd, allocindir);
+LIST_HEAD(allocdirecthd, allocdirect);
+TAILQ_HEAD(allocdirectlst, allocdirect);
+
+/*
+ * The "pagedep" structure tracks the various dependencies related to
+ * a particular directory page. If a directory page has any dependencies,
+ * it will have a pagedep linked to its associated buffer. The
+ * pd_dirremhd list holds the list of dirrem requests which decrement
+ * inode reference counts. These requests are processed after the
+ * directory page with the corresponding zero'ed entries has been
+ * written. The pd_diraddhd list maintains the list of diradd requests
+ * which cannot be committed until their corresponding inode has been
+ * written to disk. Because a directory may have many new entries
+ * being created, several lists are maintained hashed on bits of the
+ * offset of the entry into the directory page to keep the lists from
+ * getting too long. Once a new directory entry has been cleared to
+ * be written, it is moved to the pd_pendinghd list. After the new
+ * entry has been written to disk it is removed from the pd_pendinghd
+ * list, any removed operations are done, and the dependency structure
+ * is freed.
+ */
+#define DAHASHSZ 6
+#define DIRADDHASH(offset) (((offset) >> 2) % DAHASHSZ)
+struct pagedep {
+	struct	worklist pd_list;	/* page buffer */
+#	define	pd_state pd_list.wk_state /* check for multiple I/O starts */
+	LIST_ENTRY(pagedep) pd_hash;	/* hashed lookup */
+	struct	mount *pd_mnt;		/* associated mount point */
+	ino_t	pd_ino;			/* associated file */
+	ufs_lbn_t pd_lbn;		/* block within file */
+	struct	dirremhd pd_dirremhd;	/* dirrem's waiting for page */
+	struct	diraddhd pd_diraddhd[DAHASHSZ]; /* diradd dir entry updates */
+	struct	diraddhd pd_pendinghd;	/* directory entries awaiting write */
+};
+
+/*
+ * The "inodedep" structure tracks the set of dependencies associated
+ * with an inode. Each block that is allocated is represented by an
+ * "allocdirect" structure (see below). It is linked onto the id_newinoupdt
+ * list until both its contents and its allocation in the cylinder
+ * group map have been written to disk. Once the dependencies have been
+ * satisfied, it is removed from the id_newinoupdt list and any followup
+ * actions such as releasing the previous block or fragment are placed
+ * on the id_inowait list. When an inode is updated (copied from the
+ * in-core inode structure to a disk buffer containing its on-disk
+ * copy), the "inodedep" structure is linked onto the buffer through
+ * its worklist. Thus it will be notified when the buffer is about
+ * to be written and when it is done. At the update time, all the
+ * elements on the id_newinoupdt list are moved to the id_inoupdt list
+ * since those changes are now relevant to the copy of the inode in the
+ * buffer. When the buffer containing the inode is written to disk, any
+ * updates listed on the id_inoupdt list are rolled back as they are
+ * not yet safe. Following the write, the changes are once again rolled
+ * forward and any actions on the id_inowait list are processed (since
+ * the previously allocated blocks are no longer claimed on the disk).
+ * The entries on the id_inoupdt and id_newinoupdt lists must be kept
+ * sorted by logical block number to speed the calculation of the size
+ * of the rolled back inode (see explanation in initiate_write_inodeblock).
+ */
+struct inodedep {
+	struct	worklist id_list;	/* buffer holding inode block */
+#	define	id_state id_list.wk_state /* inode dependency state */
+	LIST_ENTRY(inodedep) id_hash;	/* hashed lookup */
+	struct	fs *id_fs;		/* associated filesystem */
+	ino_t	id_ino;			/* dependent inode */
+	nlink_t	id_nlinkdelta;		/* saved effective link count */
+	struct	dinode *id_savedino;	/* saved dinode contents */
+	LIST_ENTRY(inodedep) id_deps;	/* bmsafemap's list of inodedep's */
+	struct	buf *id_buf;		/* related bmsafemap (if pending) */
+	off_t	id_savedsize;		/* file size saved during rollback */
+	struct	workhead id_pendinghd;	/* entries awaiting directory write */
+	struct	workhead id_inowait;	/* operations after inode written */
+	struct	allocdirectlst id_inoupdt; /* updates before inode written */
+	struct	allocdirectlst id_newinoupdt; /* updates when inode written */
+};
+
+/*
+ * A "newblk" structure is attached to a bmsafemap structure when a block
+ * or fragment is allocated from a cylinder group. Its state is set to
+ * DEPCOMPLETE when its cylinder group map is written. It is consumed by
+ * an associated allocdirect or allocindir allocation which will attach
+ * themselves to the bmsafemap structure if the newblk's DEPCOMPLETE flag
+ * is not set (i.e., its cylinder group map has not been written).
+ */ 
+struct newblk {
+	LIST_ENTRY(newblk) nb_hash;	/* hashed lookup */
+	struct	fs *nb_fs;		/* associated filesystem */
+	ufs_daddr_t nb_newblkno;	/* allocated block number */
+	int	nb_state;		/* state of bitmap dependency */
+	LIST_ENTRY(newblk) nb_deps;	/* bmsafemap's list of newblk's */
+	struct	bmsafemap *nb_bmsafemap; /* associated bmsafemap */
+};
+
+/*
+ * A "bmsafemap" structure maintains a list of dependency structures
+ * that depend on the update of a particular cylinder group map.
+ * It has lists for newblks, allocdirects, allocindirs, and inodedeps.
+ * It is attached to the buffer of a cylinder group block when any of
+ * these things are allocated from the cylinder group. It is freed
+ * after the cylinder group map is written and the state of its
+ * dependencies are updated with DEPCOMPLETE to indicate that it has
+ * been processed.
+ */
+struct bmsafemap {
+	struct	worklist sm_list;	/* cylgrp buffer */
+	struct	buf *sm_buf;		/* associated buffer */
+	struct	allocdirecthd sm_allocdirecthd; /* allocdirect deps */
+	struct	allocindirhd sm_allocindirhd; /* allocindir deps */
+	struct	inodedephd sm_inodedephd; /* inodedep deps */
+	struct	newblkhd sm_newblkhd;	/* newblk deps */
+};
+
+/*
+ * An "allocdirect" structure is attached to an "inodedep" when a new block
+ * or fragment is allocated and pointed to by the inode described by
+ * "inodedep". The worklist is linked to the buffer that holds the block.
+ * When the block is first allocated, it is linked to the bmsafemap
+ * structure associated with the buffer holding the cylinder group map
+ * from which it was allocated. When the cylinder group map is written
+ * to disk, ad_state has the DEPCOMPLETE flag set. When the block itself
+ * is written, the COMPLETE flag is set. Once both the cylinder group map
+ * and the data itself have been written, it is safe to write the inode
+ * that claims the block. If there was a previous fragment that had been
+ * allocated before the file was increased in size, the old fragment may
+ * be freed once the inode claiming the new block is written to disk.
+ * This ad_fragfree request is attached to the id_inowait list of the
+ * associated inodedep (pointed to by ad_inodedep) for processing after
+ * the inode is written.
+ */
+struct allocdirect {
+	struct	worklist ad_list;	/* buffer holding block */
+#	define	ad_state ad_list.wk_state /* block pointer state */
+	TAILQ_ENTRY(allocdirect) ad_next; /* inodedep's list of allocdirect's */
+	ufs_lbn_t ad_lbn;		/* block within file */
+	ufs_daddr_t ad_newblkno;	/* new value of block pointer */
+	ufs_daddr_t ad_oldblkno;	/* old value of block pointer */
+	long	ad_newsize;		/* size of new block */
+	long	ad_oldsize;		/* size of old block */
+	LIST_ENTRY(allocdirect) ad_deps; /* bmsafemap's list of allocdirect's */
+	struct	buf *ad_buf;		/* cylgrp buffer (if pending) */
+	struct	inodedep *ad_inodedep;	/* associated inodedep */
+	struct	freefrag *ad_freefrag;	/* fragment to be freed (if any) */
+};
+
+/*
+ * A single "indirdep" structure manages all allocation dependencies for
+ * pointers in an indirect block. The up-to-date state of the indirect
+ * block is stored in ir_savedata. The set of pointers that may be safely
+ * written to the disk is stored in ir_safecopy. The state field is used
+ * only to track whether the buffer is currently being written (in which
+ * case it is not safe to update ir_safecopy). Ir_deplisthd contains the
+ * list of allocindir structures, one for each block that needs to be
+ * written to disk. Once the block and its bitmap allocation have been
+ * written the safecopy can be updated to reflect the allocation and the
+ * allocindir structure freed. If ir_state indicates that an I/O on the
+ * indirect block is in progress when ir_safecopy is to be updated, the
+ * update is deferred by placing the allocindir on the ir_donehd list.
+ * When the I/O on the indirect block completes, the entries on the
+ * ir_donehd list are processed by updating their corresponding ir_safecopy
+ * pointers and then freeing the allocindir structure.
+ */
+struct indirdep {
+	struct	worklist ir_list;	/* buffer holding indirect block */
+#	define	ir_state ir_list.wk_state /* indirect block pointer state */
+	ufs_daddr_t *ir_saveddata;	/* buffer cache contents */
+	struct	buf *ir_savebp;		/* buffer holding safe copy */
+	struct	allocindirhd ir_donehd;	/* done waiting to update safecopy */
+	struct	allocindirhd ir_deplisthd; /* allocindir deps for this block */
+};
+
+/*
+ * An "allocindir" structure is attached to an "indirdep" when a new block
+ * is allocated and pointed to by the indirect block described by the
+ * "indirdep". The worklist is linked to the buffer that holds the new block.
+ * When the block is first allocated, it is linked to the bmsafemap
+ * structure associated with the buffer holding the cylinder group map
+ * from which it was allocated. When the cylinder group map is written
+ * to disk, ai_state has the DEPCOMPLETE flag set. When the block itself
+ * is written, the COMPLETE flag is set. Once both the cylinder group map
+ * and the data itself have been written, it is safe to write the entry in
+ * the indirect block that claims the block; the "allocindir" dependency 
+ * can then be freed as it is no longer applicable.
+ */
+struct allocindir {
+	struct	worklist ai_list;	/* buffer holding indirect block */
+#	define	ai_state ai_list.wk_state /* indirect block pointer state */
+	LIST_ENTRY(allocindir) ai_next;	/* indirdep's list of allocindir's */
+	int	ai_offset;		/* pointer offset in indirect block */
+	ufs_daddr_t ai_newblkno;	/* new block pointer value */
+	ufs_daddr_t ai_oldblkno;	/* old block pointer value */
+	struct	freefrag *ai_freefrag;	/* block to be freed when complete */
+	struct	indirdep *ai_indirdep;	/* address of associated indirdep */
+	LIST_ENTRY(allocindir) ai_deps;	/* bmsafemap's list of allocindir's */
+	struct	buf *ai_buf;		/* cylgrp buffer (if pending) */
+};
+
+/*
+ * A "freefrag" structure is attached to an "inodedep" when a previously
+ * allocated fragment is replaced with a larger fragment, rather than extended.
+ * The "freefrag" structure is constructed and attached when the replacement
+ * block is first allocated. It is processed after the inode claiming the
+ * bigger block that replaces it has been written to disk. Note that the
+ * ff_state field is is used to store the uid, so may lose data. However,
+ * the uid is used only in printing an error message, so is not critical.
+ * Keeping it in a short keeps the data structure down to 32 bytes.
+ */
+struct freefrag {
+	struct	worklist ff_list;	/* id_inowait or delayed worklist */
+#	define	ff_state ff_list.wk_state /* owning user; should be uid_t */
+	struct	vnode *ff_devvp;	/* filesystem device vnode */
+	struct	fs *ff_fs;		/* addr of superblock */
+	ufs_daddr_t ff_blkno;		/* fragment physical block number */
+	long	ff_fragsize;		/* size of fragment being deleted */
+	ino_t	ff_inum;		/* owning inode number */
+};
+
+/*
+ * A "freeblks" structure is attached to an "inodedep" when the
+ * corresponding file's length is reduced to zero. It records all
+ * the information needed to free the blocks of a file after its
+ * zero'ed inode has been written to disk.
+ */
+struct freeblks {
+	struct	worklist fb_list;	/* id_inowait or delayed worklist */
+	ino_t	fb_previousinum;	/* inode of previous owner of blocks */
+	struct	vnode *fb_devvp;	/* filesystem device vnode */
+	struct	fs *fb_fs;		/* addr of superblock */
+	off_t	fb_oldsize;		/* previous file size */
+	off_t	fb_newsize;		/* new file size */
+	int	fb_chkcnt;		/* used to check cnt of blks released */
+	uid_t	fb_uid;			/* uid of previous owner of blocks */
+	ufs_daddr_t fb_dblks[NDADDR];	/* direct blk ptrs to deallocate */
+	ufs_daddr_t fb_iblks[NIADDR];	/* indirect blk ptrs to deallocate */
+};
+
+/*
+ * A "freefile" structure is attached to an inode when its
+ * link count is reduced to zero. It marks the inode as free in
+ * the cylinder group map after the zero'ed inode has been written
+ * to disk and any associated blocks and fragments have been freed.
+ */
+struct freefile {
+	struct	worklist fx_list;	/* id_inowait or delayed worklist */
+	mode_t	fx_mode;		/* mode of inode */
+	ino_t	fx_oldinum;		/* inum of the unlinked file */
+	struct	vnode *fx_devvp;	/* filesystem device vnode */
+	struct	fs *fx_fs;		/* addr of superblock */
+};
+
+/*
+ * A "diradd" structure is linked to an "inodedep" id_inowait list when a
+ * new directory entry is allocated that references the inode described
+ * by "inodedep". When the inode itself is written (either the initial
+ * allocation for new inodes or with the increased link count for
+ * existing inodes), the COMPLETE flag is set in da_state. If the entry
+ * is for a newly allocated inode, the "inodedep" structure is associated
+ * with a bmsafemap which prevents the inode from being written to disk
+ * until the cylinder group has been updated. Thus the da_state COMPLETE
+ * flag cannot be set until the inode bitmap dependency has been removed.
+ * When creating a new file, it is safe to write the directory entry that
+ * claims the inode once the referenced inode has been written. Since
+ * writing the inode clears the bitmap dependencies, the DEPCOMPLETE flag
+ * in the diradd can be set unconditionally when creating a file. When
+ * creating a directory, there are two additional dependencies described by
+ * mkdir structures (see their description below). When these dependencies
+ * are resolved the DEPCOMPLETE flag is set in the diradd structure.
+ * If there are multiple links created to the same inode, there will be
+ * a separate diradd structure created for each link. The diradd is
+ * linked onto the pg_diraddhd list of the pagedep for the directory
+ * page that contains the entry. When a directory page is written,
+ * the pg_diraddhd list is traversed to rollback any entries that are
+ * not yet ready to be written to disk. If a directory entry is being
+ * changed (by rename) rather than added, the DIRCHG flag is set and
+ * the da_previous entry points to the entry that will be "removed"
+ * once the new entry has been committed. During rollback, entries
+ * with da_previous are replaced with the previous inode number rather
+ * than zero.
+ *
+ * The overlaying of da_pagedep and da_previous is done to keep the
+ * structure down to 32 bytes in size on a 32-bit machine. If a
+ * da_previous entry is present, the pointer to its pagedep is available
+ * in the associated dirrem entry. If the DIRCHG flag is set, the
+ * da_previous entry is valid; if not set the da_pagedep entry is valid.
+ * The DIRCHG flag never changes; it is set when the structure is created
+ * if appropriate and is never cleared.
+ */
+struct diradd {
+	struct	worklist da_list;	/* id_inowait and id_pendinghd list */
+#	define	da_state da_list.wk_state /* state of the new directory entry */
+	LIST_ENTRY(diradd) da_pdlist;	/* pagedep holding directory block */
+	doff_t	da_offset;		/* offset of new dir entry in dir blk */
+	ino_t	da_newinum;		/* inode number for the new dir entry */
+	union {
+	struct	dirrem *dau_previous;	/* entry being replaced in dir change */
+	struct	pagedep *dau_pagedep;	/* pagedep dependency for addition */
+	} da_un;
+};
+#define da_previous da_un.dau_previous
+#define da_pagedep da_un.dau_pagedep
+
+/*
+ * Two "mkdir" structures are needed to track the additional dependencies
+ * associated with creating a new directory entry. Normally a directory
+ * addition can be committed as soon as the newly referenced inode has been
+ * written to disk with its increased link count. When a directory is
+ * created there are two additional dependencies: writing the directory
+ * data block containing the "." and ".." entries (MKDIR_BODY) and writing
+ * the parent inode with the increased link count for ".." (MKDIR_PARENT).
+ * These additional dependencies are tracked by two mkdir structures that
+ * reference the associated "diradd" structure. When they have completed,
+ * they set the DEPCOMPLETE flag on the diradd so that it knows that its
+ * extra dependencies have been completed. The md_state field is used only
+ * to identify which type of dependency the mkdir structure is tracking.
+ * It is not used in the mainline code for any purpose other than consistency
+ * checking. All the mkdir structures in the system are linked together on
+ * a list. This list is needed so that a diradd can find its associated
+ * mkdir structures and deallocate them if it is prematurely freed (as for
+ * example if a mkdir is immediately followed by a rmdir of the same directory).
+ * Here, the free of the diradd must traverse the list to find the associated
+ * mkdir structures that reference it. The deletion would be faster if the
+ * diradd structure were simply augmented to have two pointers that referenced
+ * the associated mkdir's. However, this would increase the size of the diradd
+ * structure from 32 to 64-bits to speed a very infrequent operation.
+ */
+struct mkdir {
+	struct	worklist md_list;	/* id_inowait or buffer holding dir */
+#	define	md_state md_list.wk_state /* type: MKDIR_PARENT or MKDIR_BODY */
+	struct	diradd *md_diradd;	/* associated diradd */
+	LIST_ENTRY(mkdir) md_mkdirs;	/* list of all mkdirs */
+};
+LIST_HEAD(mkdirlist, mkdir) mkdirlisthd;
+
+/*
+ * A "dirrem" structure describes an operation to decrement the link
+ * count on an inode. The dirrem structure is attached to the pg_dirremhd
+ * list of the pagedep for the directory page that contains the entry.
+ * It is processed after the directory page with the deleted entry has
+ * been written to disk.
+ *
+ * The overlaying of dm_pagedep and dm_dirinum is done to keep the
+ * structure down to 32 bytes in size on a 32-bit machine. It works
+ * because they are never used concurrently.
+ */
+struct dirrem {
+	struct	worklist dm_list;	/* delayed worklist */
+#	define	dm_state dm_list.wk_state /* state of the old directory entry */
+	LIST_ENTRY(dirrem) dm_next;	/* pagedep's list of dirrem's */
+	struct	mount *dm_mnt;		/* associated mount point */
+	ino_t	dm_oldinum;		/* inum of the removed dir entry */
+	union {
+	struct	pagedep *dmu_pagedep;	/* pagedep dependency for remove */
+	ino_t	dmu_dirinum;		/* parent inode number (for rmdir) */
+	} dm_un;
+};
+#define dm_pagedep dm_un.dmu_pagedep
+#define dm_dirinum dm_un.dmu_dirinum