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Encumbrance review done.
Add copyright and license words consistent with GPL.
Refer to http://fsg.melbourne.sgi.com/reviews/ for details.

There is a slight change in the license terms and conditions words
to go with the copyrights, so most of the files are not getting
new GPL's, just updated versions ... but there are 20-30 more files
here as well.

/*
 * Copyright (C) 1999 Silicon Graphics, Inc.  All Rights Reserved.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
 */
#ident "$Revision: 1.89 $"

/*
 * This file contains the implementation of the xfs_buf_log_item.
 * It contains the item operations used to manipulate the buf log
 * items as well as utility routines used by the buffer specific
 * transaction routines.
 */

#if defined(__linux__)
#include <xfs_linux.h>
#endif

#include <limits.h>
#ifdef SIM
#define _KERNEL 1
#endif
#include <sys/param.h>
#include "xfs_buf.h"
#include <sys/atomic_ops.h>
#include <sys/debug.h>
#ifdef SIM
#undef _KERNEL
#endif
#include <sys/vnode.h>
#include <sys/kmem.h>
#include <sys/errno.h>
#ifdef SIM
#include <bstring.h>
#include <stdio.h>
#else
#include <sys/systm.h>
#endif
#include <sys/ktrace.h>
#include <sys/cmn_err.h>
#include <sys/uuid.h>
#include "xfs_macros.h"
#include "xfs_types.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"
#include "xfs_sb.h"
#include "xfs_dir.h"
#include "xfs_mount.h"
#include "xfs_trans_priv.h"
#include "xfs_rw.h" 
#include "xfs_bit.h"

#ifdef SIM
#include "sim.h"
#endif

#define	ROUNDUPNBWORD(x)	(((x) + (NBWORD - 1)) & ~(NBWORD - 1))

zone_t	*xfs_buf_item_zone;

#if 0
STATIC void	xfs_buf_item_set_bit(uint *, uint, uint);
#endif

#ifdef	XFS_TRANS_DEBUG
STATIC void
xfs_buf_item_log_debug(
	xfs_buf_log_item_t	*bip,
	uint			first,
	uint			last);

STATIC void
xfs_buf_item_log_check(
	xfs_buf_log_item_t	*bip);
#else
#define		xfs_buf_item_log_debug(x,y,z)
#define 	xfs_buf_item_log_check(x)
#endif

STATIC void	xfs_buf_error_relse(xfs_buf_t *bp);

/*
 * This returns the number of log iovecs needed to log the
 * given buf log item.
 *
 * It calculates this as 1 iovec for the buf log format structure
 * and 1 for each stretch of non-contiguous chunks to be logged.
 * Contiguous chunks are logged in a single iovec.
 *
 * If the XFS_BLI_STALE flag has been set, then log nothing.
 */
uint
xfs_buf_item_size(
	xfs_buf_log_item_t	*bip)
{
	uint	nvecs;
	int	next_bit;
	int	last_bit;

	ASSERT(bip->bli_refcount > 0);
	if (bip->bli_flags & XFS_BLI_STALE) {
		/*
		 * The buffer is stale, so all we need to log
		 * is the buf log format structure with the
		 * cancel flag in it.
		 */
		xfs_buf_item_trace("SIZE STALE", bip);
		ASSERT(bip->bli_format.blf_flags & XFS_BLI_CANCEL);
		return 1;
	}

	ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
	nvecs = 1;
	last_bit = xfs_buf_item_next_bit(bip->bli_format.blf_data_map,
					 bip->bli_format.blf_map_size, 0);
	ASSERT(last_bit != -1);
	nvecs++;
	while (last_bit != -1) {	
		/*
		 * This takes the bit number to start looking from and
		 * returns the next set bit from there.  It returns -1
		 * if there are no more bits set or the start bit is
		 * beyond the end of the bitmap.
		 */
		next_bit = xfs_buf_item_next_bit(bip->bli_format.blf_data_map,
						 bip->bli_format.blf_map_size,
						 last_bit + 1);
		/*
		 * If we run out of bits, leave the loop,
		 * else if we find a new set of bits bump the number of vecs,
		 * else keep scanning the current set of bits.
		 */
		if (next_bit == -1) {
			last_bit = -1;
		} else if (next_bit != last_bit + 1) {
			last_bit = next_bit;	
			nvecs++;
		} else {
			last_bit++;
		}
	}

	xfs_buf_item_trace("SIZE NORM", bip);
	return nvecs;
}

/*
 * This is called to fill in the vector of log iovecs for the
 * given log buf item.  It fills the first entry with a buf log
 * format structure, and the rest point to contiguous chunks
 * within the buffer.
 */
void
xfs_buf_item_format(
	xfs_buf_log_item_t	*bip,
	xfs_log_iovec_t		*log_vector)
{
	uint		base_size;
	uint		nvecs;
	xfs_log_iovec_t	*vecp;
	xfs_buf_t	*bp;
	int		first_bit;
	int		last_bit;
	int		next_bit;
	uint		nbits;
	uint		buffer_offset;

	ASSERT(bip->bli_refcount > 0);
	ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
	       (bip->bli_flags & XFS_BLI_STALE));
	bp = bip->bli_buf;
	ASSERT(BP_ISMAPPED(bp));
	vecp = log_vector;

	/*
	 * The size of the base structure is the size of the
	 * declared structure plus the space for the extra words
	 * of the bitmap.  We subtract one from the map size, because
	 * the first element of the bitmap is accounted for in the
	 * size of the base structure.
	 */
	base_size =
		(uint)(sizeof(xfs_buf_log_format_t) +
		       ((bip->bli_format.blf_map_size - 1) * sizeof(uint)));
	vecp->i_addr = (caddr_t)&bip->bli_format;
	vecp->i_len = base_size;
	vecp++;
	nvecs = 1;

	if (bip->bli_flags & XFS_BLI_STALE) {
		/*
		 * The buffer is stale, so all we need to log
		 * is the buf log format structure with the
		 * cancel flag in it.
		 */
		xfs_buf_item_trace("FORMAT STALE", bip);
		ASSERT(bip->bli_format.blf_flags & XFS_BLI_CANCEL);
		bip->bli_format.blf_size = nvecs;
		return;
	}

	/*
	 * Fill in an iovec for each set of contiguous chunks.
	 */
	first_bit = xfs_buf_item_next_bit(bip->bli_format.blf_data_map,
					 bip->bli_format.blf_map_size, 0);
	ASSERT(first_bit != -1);
	last_bit = first_bit;
	nbits = 1;
	for (;;) {
		/*
		 * This takes the bit number to start looking from and
		 * returns the next set bit from there.  It returns -1
		 * if there are no more bits set or the start bit is
		 * beyond the end of the bitmap.
		 */
		next_bit = xfs_buf_item_next_bit(bip->bli_format.blf_data_map,
						 bip->bli_format.blf_map_size,
						 (uint)last_bit + 1);
		/*
		 * If we run out of bits fill in the last iovec and get
		 * out of the loop.
		 * Else if we start a new set of bits then fill in the
		 * iovec for the series we were looking at and start
		 * counting the bits in the new one.
		 * Else we're still in the same set of bits so just
		 * keep counting and scanning.
		 */
		if (next_bit == -1) {
			buffer_offset = first_bit * XFS_BLI_CHUNK;
			vecp->i_addr = XFS_BUF_PTR(bp) + buffer_offset;
			vecp->i_len = nbits * XFS_BLI_CHUNK;
			nvecs++;
			break;
		} else if (next_bit != last_bit + 1) {
			buffer_offset = first_bit * XFS_BLI_CHUNK;
			vecp->i_addr = XFS_BUF_PTR(bp) + buffer_offset;
			vecp->i_len = nbits * XFS_BLI_CHUNK;
			nvecs++;
			vecp++;
			first_bit = next_bit;
			last_bit = next_bit;	
			nbits = 1;
		} else {
			last_bit++;
			nbits++;
		}
	}
	bip->bli_format.blf_size = nvecs;

	/*
	 * Check to make sure everything is consistent.
	 */
	xfs_buf_item_trace("FORMAT NORM", bip);
	xfs_buf_item_log_check(bip);
}

/*
 * This is called to pin the buffer associated with the buf log
 * item in memory so it cannot be written out.  Simply call bpin()
 * on the buffer to do this.
 */
void
xfs_buf_item_pin(
	xfs_buf_log_item_t	*bip)
{
	xfs_buf_t	*bp;

	bp = bip->bli_buf;
	ASSERT(XFS_BUF_ISBUSY(bp));
	ASSERT(bip->bli_refcount > 0);
	ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
	       (bip->bli_flags & XFS_BLI_STALE));
	xfs_buf_item_trace("PIN", bip);
	xfs_buftrace("XFS_PIN", bp);
	xfs_bpin(bp);
}


/*
 * This is called to unpin the buffer associated with the buf log
 * item which was previously pinned with a call to xfs_buf_item_pin().
 * Just call bunpin() on the buffer to do this.
 *
 * Also drop the reference to the buf item for the current transaction.
 * If the XFS_BLI_STALE flag is set and we are the last reference,
 * then free up the buf log item and unlock the buffer.
 */
void
xfs_buf_item_unpin(
	xfs_buf_log_item_t	*bip)
{
	xfs_mount_t	*mp;
	xfs_buf_t	*bp;
	int		refcount;
	SPLDECL(s);

	bp = bip->bli_buf;
	ASSERT(bp != NULL);
	ASSERT(XFS_BUF_FSPRIVATE(bp, xfs_buf_log_item_t *) == bip);
	ASSERT(bip->bli_refcount > 0);
	xfs_buf_item_trace("UNPIN", bip);
	xfs_buftrace("XFS_UNPIN", bp);

	refcount = atomicAddInt(&bip->bli_refcount, -1);
	mp = bip->bli_item.li_mountp;
	xfs_bunpin(bp);
	if ((refcount == 0) && (bip->bli_flags & XFS_BLI_STALE)) {
		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
		ASSERT(!(XFS_BUF_ISDELAYWRITE(bp)));
		ASSERT(XFS_BUF_ISSTALE(bp));
		ASSERT(bp->b_pincount == 0);
		ASSERT(bip->bli_format.blf_flags & XFS_BLI_CANCEL);
		xfs_buf_item_trace("UNPIN STALE", bip);
		xfs_buftrace("XFS_UNPIN STALE", bp);
		AIL_LOCK(mp,s);
		/*
		 * If we get called here because of an IO error, we may
		 * or may not have the item on the AIL. xfs_trans_delete_ail()
		 * will take care of that situation.
		 * xfs_trans_delete_ail() drops the AIL lock.
		 */
		xfs_trans_delete_ail(mp, (xfs_log_item_t *)bip, s);
		xfs_buf_item_relse(bp);
		ASSERT(XFS_BUF_FSPRIVATE(bp, void *) == NULL);
		xfs_buf_relse(bp);
	}

}

/*
 * this is called from uncommit in the forced-shutdown path.
 * we need to check to see if the reference count on the log item
 * is going to drop to zero.  If so, unpin will free the log item
 * so we need to free the item's descriptor (that points to the item)
 * in the transaction.
 */
void
xfs_buf_item_unpin_remove(
	xfs_buf_log_item_t	*bip,
	xfs_trans_t		*tp)
{
	/* REFERENCED */
	xfs_buf_t		*bp;
	xfs_log_item_desc_t	*lidp;

	bp = bip->bli_buf;
	/*
	 * will xfs_buf_item_unpin() call xfs_buf_item_relse()?
	 */
	if (bip->bli_refcount == 1 && (bip->bli_flags & XFS_BLI_STALE)) {
		ASSERT(XFS_BUF_VALUSEMA(bip->bli_buf) <= 0);
		xfs_buf_item_trace("UNPIN REMOVE", bip);
      	xfs_buftrace("XFS_UNPIN_REMOVE", bp);
		/*
		 * yes -- clear the xaction descriptor in-use flag
		 * and free the chunk if required.  We can safely
		 * do some work here and then call buf_item_unpin
		 * to do the rest because if the if is true, then
		 * we are holding the buffer locked so no one else
		 * will be able to bump up the refcount.
		 */
		lidp = xfs_trans_find_item(tp, (xfs_log_item_t *) bip);
		xfs_trans_free_item(tp, lidp);
		/*
		 * Since the transaction no longer refers to the buffer,
		 * the buffer should no longer refer to the transaction.
		 */
		XFS_BUF_SET_FSPRIVATE2(bp, NULL);
	}

	xfs_buf_item_unpin(bip);

	return;
}

/*
 * This is called to attempt to lock the buffer associated with this
 * buf log item.  Don't sleep on the buffer lock.  If we can't get
 * the lock right away, return 0.  If we can get the lock, pull the
 * buffer from the free list, mark it busy, and return 1.
 */
uint
xfs_buf_item_trylock(
	xfs_buf_log_item_t	*bip)
{
	xfs_buf_t	*bp;

	bp = bip->bli_buf;

	if (XFS_BUF_ISPINNED(bp)) {
		return XFS_ITEM_PINNED;
	}

	if (!XFS_BUF_CPSEMA(bp)) {
		return XFS_ITEM_LOCKED;
	}

	/*
	 * Remove the buffer from the free list.  Only do this
	 * if it's on the free list.  Private buffers like the
	 * superblock buffer are not.
	 */
#ifndef _USING_PAGEBUF_T
	if (bp->av_forw != NULL) {
		notavail(bp);
	}
#endif

	ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
	xfs_buf_item_trace("TRYLOCK SUCCESS", bip);
	return XFS_ITEM_SUCCESS;
}

/*
 * Release the buffer associated with the buf log item.
 * If there is no dirty logged data associated with the
 * buffer recorded in the buf log item, then free the
 * buf log item and remove the reference to it in the
 * buffer.
 *
 * This call ignores the recursion count.  It is only called
 * when the buffer should REALLY be unlocked, regardless
 * of the recursion count.
 *
 * If the XFS_BLI_HOLD flag is set in the buf log item, then
 * free the log item if necessary but do not unlock the buffer.
 * This is for support of xfs_trans_bhold(). Make sure the
 * XFS_BLI_HOLD field is cleared if we don't free the item.
 */
void
xfs_buf_item_unlock(
	xfs_buf_log_item_t	*bip)
{
	int		aborted;
	xfs_buf_t	*bp;
	uint		hold;

	bp = bip->bli_buf;
	xfs_buftrace("XFS_UNLOCK", bp);

	/*
	 * Clear the buffer's association with this transaction.
	 */
	XFS_BUF_SET_FSPRIVATE2(bp, NULL);

	/*
	 * If this is a transaction abort, don't return early.
	 * Instead, allow the brelse to happen.
	 * Normally it would be done for stale (cancelled) buffers
	 * at unpin time, but we'll never go through the pin/unpin
	 * cycle if we abort inside commit.
	 */
	aborted = (bip->bli_item.li_flags & XFS_LI_ABORTED) != 0;

	/*
	 * If the buf item is marked stale, then don't do anything.
	 * We'll unlock the buffer and free the buf item when the
	 * buffer is unpinned for the last time.
	 */
	if (bip->bli_flags & XFS_BLI_STALE) {
		bip->bli_flags &= ~XFS_BLI_LOGGED;
		xfs_buf_item_trace("UNLOCK STALE", bip);
		ASSERT(bip->bli_format.blf_flags & XFS_BLI_CANCEL);
		if (!aborted)
			return;
	}

	/*
	 * Drop the transaction's reference to the log item if
	 * it was not logged as part of the transaction.  Otherwise
	 * we'll drop the reference in xfs_buf_item_unpin() when
	 * the transaction is really through with the buffer.
	 */
	if (!(bip->bli_flags & XFS_BLI_LOGGED)) {
		(void) atomicAddInt(&bip->bli_refcount, -1);
	} else {
		/*
		 * Clear the logged flag since this is per
		 * transaction state.
		 */
		bip->bli_flags &= ~XFS_BLI_LOGGED;
	}

	/*
	 * Before possibly freeing the buf item, determine if we should
	 * release the buffer at the end of this routine.
	 */
	hold = bip->bli_flags & XFS_BLI_HOLD;
	xfs_buf_item_trace("UNLOCK", bip);

	/*
	 * If the buf item isn't tracking any data, free it.
	 * Otherwise, if XFS_BLI_HOLD is set clear it.
	 */
	if (xfs_buf_item_bits(bip->bli_format.blf_data_map,
			      bip->bli_format.blf_map_size, 0) == 0) {
		xfs_buf_item_relse(bp);
	} else if (hold) {
		bip->bli_flags &= ~XFS_BLI_HOLD;
	}

	/*
	 * Release the buffer if XFS_BLI_HOLD was not set.
	 */
	if (!hold) {
		xfs_buf_relse(bp);
	}
}

/*
 * This is called to find out where the oldest active copy of the
 * buf log item in the on disk log resides now that the last log
 * write of it completed at the given lsn.
 * We always re-log all the dirty data in a buffer, so usually the
 * latest copy in the on disk log is the only one that matters.  For
 * those cases we simply return the given lsn.
 * 
 * The one exception to this is for buffers full of newly allocated
 * inodes.  These buffers are only relogged with the XFS_BLI_INODE_BUF
 * flag set, indicating that only the di_next_unlinked fields from the
 * inodes in the buffers will be replayed during recovery.  If the
 * original newly allocated inode images have not yet been flushed
 * when the buffer is so relogged, then we need to make sure that we
 * keep the old images in the 'active' portion of the log.  We do this
 * by returning the original lsn of that transaction here rather than
 * the current one.
 */
xfs_lsn_t
xfs_buf_item_committed(
	xfs_buf_log_item_t	*bip,
	xfs_lsn_t		lsn)
{
	xfs_buf_item_trace("COMMITTED", bip);
	if ((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) &&
	    (bip->bli_item.li_lsn != 0)) {
		return bip->bli_item.li_lsn;
	}
	return (lsn);
}

/*
 * This is called when the transaction holding the buffer is aborted.
 * Just behave as if the transaction had been cancelled. If we're shutting down
 * and have aborted this transaction, we'll trap this buffer when it tries to
 * get written out.
 */
void
xfs_buf_item_abort(
	xfs_buf_log_item_t	*bip)
{
	xfs_buf_t 	*bp;

	bp = bip->bli_buf;
	buftrace("XFS_ABORT", bp);
	XFS_BUF_SUPER_STALE(bp);
	xfs_buf_item_unlock(bip);
	return;
}

/*
 * This is called to asynchronously write the buffer associated with this
 * buf log item out to disk. The buffer will already have been locked by
 * a successful call to xfs_buf_item_trylock().  If the buffer still has
 * B_DELWRI set, then get it going out to disk with a call to bawrite().
 * If not, then just release the buffer.
 */
void
xfs_buf_item_push(
	xfs_buf_log_item_t	*bip)
{
	xfs_buf_t	*bp;

	ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
	xfs_buf_item_trace("PUSH", bip);

	bp = bip->bli_buf;

	if (XFS_BUF_ISDELAYWRITE(bp)) {
		xfs_bawrite(bip->bli_item.li_mountp, bp);
	} else {
		xfs_buf_relse(bp);
	}
}

/* ARGSUSED */
void
xfs_buf_item_committing(xfs_buf_log_item_t *bip, xfs_lsn_t commit_lsn)
{
}

/*
 * This is the ops vector shared by all buf log items.
 */
struct xfs_item_ops xfs_buf_item_ops = {
	(uint(*)(xfs_log_item_t*))xfs_buf_item_size,
	(void(*)(xfs_log_item_t*, xfs_log_iovec_t*))xfs_buf_item_format,
	(void(*)(xfs_log_item_t*))xfs_buf_item_pin,
	(void(*)(xfs_log_item_t*))xfs_buf_item_unpin,
	(void(*)(xfs_log_item_t*, xfs_trans_t *))xfs_buf_item_unpin_remove,
	(uint(*)(xfs_log_item_t*))xfs_buf_item_trylock,
	(void(*)(xfs_log_item_t*))xfs_buf_item_unlock,
	(xfs_lsn_t(*)(xfs_log_item_t*, xfs_lsn_t))xfs_buf_item_committed,
	(void(*)(xfs_log_item_t*))xfs_buf_item_push,
	(void(*)(xfs_log_item_t*))xfs_buf_item_abort,
	NULL,
	(void(*)(xfs_log_item_t*, xfs_lsn_t))xfs_buf_item_committing
};


/*
 * Allocate a new buf log item to go with the given buffer.
 * Set the buffer's b_fsprivate field to point to the new
 * buf log item.  If there are other item's attached to the
 * buffer (see xfs_buf_attach_iodone() below), then put the
 * buf log item at the front.
 */
void
xfs_buf_item_init(
	xfs_buf_t	*bp,
	xfs_mount_t	*mp)
{
	xfs_log_item_t		*lip;
	xfs_buf_log_item_t	*bip;
	int			chunks;
	int			map_size;

	/*
	 * Check to see if there is already a buf log item for
	 * this buffer.  If there is, it is guaranteed to be
	 * the first.  If we do already have one, there is
	 * nothing to do here so return.
	 */
	if (XFS_BUF_FSPRIVATE3(bp, xfs_mount_t *) != mp)
		XFS_BUF_SET_FSPRIVATE3(bp, mp);
	XFS_BUF_SET_BDSTRAT_FUNC(bp, xfs_bdstrat_cb);
	if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
		lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
		if (lip->li_type == XFS_LI_BUF) {
			return;
		}
	}
		
	/*
	 * chunks is the number of XFS_BLI_CHUNK size pieces
	 * the buffer can be divided into. Make sure not to
	 * truncate any pieces.  map_size is the size of the
	 * bitmap needed to describe the chunks of the buffer.
	 */
	chunks = (int)((XFS_BUF_COUNT(bp) + (XFS_BLI_CHUNK - 1)) >> XFS_BLI_SHIFT);
	map_size = (int)((chunks + NBWORD) >> BIT_TO_WORD_SHIFT);

	bip = (xfs_buf_log_item_t*)kmem_zone_zalloc(xfs_buf_item_zone,
						    KM_SLEEP);
	bip->bli_item.li_type = XFS_LI_BUF;
	bip->bli_item.li_ops = &xfs_buf_item_ops;
	bip->bli_item.li_mountp = mp;
	bip->bli_buf = bp;
	bip->bli_format.blf_type = XFS_LI_BUF;
	bip->bli_format.blf_blkno = (__int64_t)XFS_BUF_ADDR(bp);
	bip->bli_format.blf_len = (ushort)BTOBB(XFS_BUF_COUNT(bp));
	bip->bli_format.blf_map_size = map_size;
#ifdef XFS_BLI_TRACE
	bip->bli_trace = ktrace_alloc(XFS_BLI_TRACE_SIZE, 0);
#endif

#ifdef XFS_TRANS_DEBUG
	/*
	 * Allocate the arrays for tracking what needs to be logged
	 * and what our callers request to be logged.  bli_orig
	 * holds a copy of the original, clean buffer for comparison
	 * against, and bli_logged keeps a 1 bit flag per byte in
	 * the buffer to indicate which bytes the callers have asked
	 * to have logged.
	 */
	bip->bli_orig = (char *)kmem_alloc(XFS_BUF_COUNT(bp), KM_SLEEP);
	bcopy(XFS_BUF_PTR(bp), bip->bli_orig, XFS_BUF_COUNT(bp));
	bip->bli_logged = (char *)kmem_zalloc(XFS_BUF_COUNT(bp) / NBBY, KM_SLEEP);
#endif

	/*
	 * Put the buf item into the list of items attached to the
	 * buffer at the front.
	 */
	if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
		bip->bli_item.li_bio_list =
				XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
	}
	XFS_BUF_SET_FSPRIVATE(bp, bip);
}


/*
 * Mark bytes first through last inclusive as dirty in the buf
 * item's bitmap.
 */
void
xfs_buf_item_log(
	xfs_buf_log_item_t	*bip,
	uint			first,
	uint			last)
{
	uint		first_bit;
	uint		last_bit;
	uint		bits_to_set;
	uint		bits_set;
	uint		word_num;
	uint		*wordp;
	uint		bit;
	uint		end_bit;
	uint		mask;

	/*
	 * Mark the item as having some dirty data for
	 * quick reference in xfs_buf_item_dirty.
	 */
	bip->bli_flags |= XFS_BLI_DIRTY;

	/*
	 * Convert byte offsets to bit numbers.
	 */
	first_bit = first >> XFS_BLI_SHIFT;
	last_bit = last >> XFS_BLI_SHIFT;

	/*
	 * Calculate the total number of bits to be set.
	 */
	bits_to_set = last_bit - first_bit + 1;	

	/*
	 * Get a pointer to the first word in the bitmap
	 * to set a bit in.
	 */
	word_num = first_bit >> BIT_TO_WORD_SHIFT;
	wordp = &(bip->bli_format.blf_data_map[word_num]);

	/*
	 * Calculate the starting bit in the first word.
	 */
	bit = first_bit & (uint)(NBWORD - 1);

	/*
	 * First set any bits in the first word of our range.
	 * If it starts at bit 0 of the word, it will be
	 * set below rather than here.  That is what the variable
	 * bit tells us. The variable bits_set tracks the number
	 * of bits that have been set so far.  End_bit is the number
	 * of the last bit to be set in this word plus one.
	 */
	if (bit) {
		end_bit = MIN(bit + bits_to_set, (uint)NBWORD);
		mask = ((1 << (end_bit - bit)) - 1) << bit;
		*wordp |= mask;
		wordp++;
		bits_set = end_bit - bit;
	} else {
		bits_set = 0;
	}

	/*
	 * Now set bits a whole word at a time that are between
	 * first_bit and last_bit.
	 */
	while ((bits_to_set - bits_set) >= NBWORD) {
		*wordp |= 0xffffffff;
		bits_set += NBWORD;
		wordp++;
	}

	/*
	 * Finally, set any bits left to be set in one last partial word.
	 */
	end_bit = bits_to_set - bits_set;
	if (end_bit) {
		mask = (1 << end_bit) - 1;
		*wordp |= mask;
	}

	xfs_buf_item_log_debug(bip, first, last);
}

#ifdef XFS_TRANS_DEBUG
/*
 * This function uses an alternate strategy for tracking the bytes
 * that the user requests to be logged.  This can then be used
 * in conjunction with the bli_orig array in the buf log item to
 * catch bugs in our callers' code.
 *
 * We also double check the bits set in xfs_buf_item_log using a
 * simple algorithm to check that every byte is accounted for.
 */
STATIC void
xfs_buf_item_log_debug(
	xfs_buf_log_item_t	*bip,
	uint			first,
	uint			last)
{
	uint	x;
	uint	byte;
	uint	nbytes;
	uint	chunk_num;
	uint	word_num;
	uint	bit_num;
	uint	bit_set;
	uint	*wordp;

	ASSERT(bip->bli_logged != NULL);
	byte = first;
	nbytes = last - first + 1;
	bfset(bip->bli_logged, first, nbytes);
	for (x = 0; x < nbytes; x++) { 
		chunk_num = byte >> XFS_BLI_SHIFT;
		word_num = chunk_num >> BIT_TO_WORD_SHIFT;
		bit_num = chunk_num & (NBWORD - 1);
		wordp = &(bip->bli_format.blf_data_map[word_num]);
		bit_set = *wordp & (1 << bit_num);
		ASSERT(bit_set);
		byte++;
	}
}

/*
 * This function is called when we flush something into a buffer without
 * logging it.  This happens for things like inodes which are logged
 * separately from the buffer.
 */
void
xfs_buf_item_flush_log_debug(
	xfs_buf_t	*bp,
	uint		first,
	uint		last)
{
	xfs_buf_log_item_t	*bip;
	uint			nbytes;

	bip = XFS_BUF_FSPRIVATE(bp, xfs_buf_log_item_t*);
	if ((bip == NULL) || (bip->bli_item.li_type != XFS_LI_BUF)) {
		return;
	}

	ASSERT(bip->bli_logged != NULL);
	nbytes = last - first + 1;
	bfset(bip->bli_logged, first, nbytes);
}

/*
 * This function is called to verify that our caller's have logged
 * all the bytes that they changed.
 *
 * It does this by comparing the original copy of the buffer stored in
 * the buf log item's bli_orig array to the current copy of the buffer
 * and ensuring that all bytes which miscompare are set in the bli_logged
 * array of the buf log item.
 */
STATIC void
xfs_buf_item_log_check(
	xfs_buf_log_item_t	*bip)
{
	char		*orig;
	char		*buffer;
	int		x;
	xfs_buf_t	*bp;

	ASSERT(bip->bli_orig != NULL);
	ASSERT(bip->bli_logged != NULL);

	bp = bip->bli_buf;
	ASSERT(XFS_BUF_COUNT(bp) > 0);
	ASSERT(XFS_BUF_PTR(bp) != NULL);
	orig = bip->bli_orig;
	buffer = XFS_BUF_PTR(bp);
	for (x = 0; x < XFS_BUF_COUNT(bp); x++) {
		if (orig[x] != buffer[x] && !btst(bip->bli_logged, x))
			cmn_err(CE_PANIC,
	"xfs_buf_item_log_check bip %x buffer %x orig %x index %d",
				bip, bp, orig, x);
	}
}
#endif /* XFS_TRANS_DEBUG */

/*
 * Count the number of bits set in the bitmap starting with bit
 * start_bit.  Size is the size of the bitmap in words.
 *
 * Do the counting by mapping a byte value to the number of set
 * bits for that value using the xfs_countbit array, i.e.
 * xfs_countbit[0] == 0, xfs_countbit[1] == 1, xfs_countbit[2] == 1,
 * xfs_countbit[3] == 2, etc.
 */
int
xfs_buf_item_bits(
	uint	*map,
	uint	size,
	uint	start_bit)
{
	register int	bits;
	register char	*bytep;
	register char	*end_map;
	int		byte_bit;

	bits = 0;
	end_map = (char*)(map + size);
	bytep = (char*)(map + (start_bit & ~0x7));
	byte_bit = start_bit & 0x7;

	/*
	 * If the caller fell off the end of the map, return 0.
	 */
	if (bytep >= end_map) {
		return (0);
	}

	/*
	 * If start_bit is not byte aligned, then process the
	 * first byte separately.
	 */
	if (byte_bit != 0) {
		/*
		 * Shift off the bits we don't want to look at,
		 * before indexing into xfs_countbit.
		 */
		bits += xfs_countbit[(*bytep >> byte_bit)];
		bytep++;
	}

	/*
	 * Count the bits in each byte until the end of the bitmap.
	 */
	while (bytep < end_map) {
		bits += xfs_countbit[*bytep];
		bytep++;
	}

	return (bits);
}	/* xfs_buf_item_bits */
	
/*
 * Count the number of contiguous bits set in the bitmap starting with bit
 * start_bit.  Size is the size of the bitmap in words.
 *
 * Do the counting by mapping a byte value to the number of set
 * bits for that value using the xfs_countbit array, i.e.
 */
int
xfs_buf_item_contig_bits(
	uint	*map,
	uint	size,
	uint	start_bit)
{
	register int	bits;
	register uint	*wordp;
	register uint	cwordp;
	register uint	*end_map;
	int		word_bit;
	int		cnt;

	bits = 0;
	end_map = (uint *)(map + size);
	wordp = (uint *)(map + (start_bit >> 5));
	word_bit = start_bit & 0x1F;

	/*
	 * If the caller fell off the end of the map, return 0.
	 */
	if (wordp >= end_map) {
		return (0);
	}

	/*
	 * If start_bit is not byte aligned, then process just the
	 * relevant bits.
	 */
	if (word_bit != 0) {
		cwordp = *wordp >> word_bit;
	} else {
		cwordp = *wordp;
		word_bit = 0;
	}

	/*
	 * Count the bits in each byte until the end of the bitmap.
	 */
	while (wordp < end_map) {
		/*
		 * Cycle through bits left in word.  If the low bit is
		 * set, we've found a 'contingous' bit.
		 */
		for (cnt = (int)(NBPW*NBBY-word_bit); cnt > 0; cnt--) {
			if (cwordp & 0x1)
				bits++;
			else
				return bits;
			cwordp >>= 1;
		}

		/* Grab another word */
		wordp++;
		cwordp = *wordp;
		word_bit = 0;
	}

	return (bits);
}	/* xfs_buf_item_contig_bits */
	
/*
 * This takes the bit number to start looking from and
 * returns the next set bit from there.  It returns -1
 * if there are no more bits set or the start bit is
 * beyond the end of the bitmap.
 *
 * Size is the number of words, not bytes, in the bitmap.
 */
int
xfs_buf_item_next_bit(
	uint	*map,
	uint	size,
	uint	start_bit)
{
	int	next_bit;
	uint	*wordp;
	uint	*end_map;
	int	word_bit;
	uint	word;

	end_map = map + size;
	wordp = map + (start_bit >> BIT_TO_WORD_SHIFT);
	word_bit = start_bit & (int)(NBWORD - 1);

	/*
	 * If the caller has stepped beyond the end of the bitmap,
	 * return -1.
	 */
	if (wordp >= end_map) {
		return (-1);
	}

	next_bit = start_bit;

	/*
	 * If the start_bit does not start on a word boundary,
	 * check the remainder of the starting word first.
	 */
	if (word_bit != 0) {
		word = *wordp >> word_bit;
		while (word != 0) {
			if (word & 1) {
				return (next_bit);
			}
			word = word >> 1;
			next_bit++;	
		}
		/*
		 * Since we don't know how many bits we looked at before
		 * word became 0, just set next_bit to the start of the
		 * next word.
		 */
		wordp++;
		next_bit = (int)ROUNDUPNBWORD(start_bit); 
	}

	/*
	 * Do word at a time checking for bits until the end of the map.
	 */
	while (wordp < end_map) {
		/*
		 * If the current word is empty, skip it.
		 */
		if (*wordp == 0) {
			wordp++;
			next_bit += NBWORD;
			continue;
		}

		/*
		 * We know we've got a bit in this word, find it.
		 */
		word = *wordp;
		for (;;) {
			if (word & 1) {
				return (next_bit);
			}
			next_bit++;
			word = word >> 1;
		}
	}

	/*
	 * If there were no more bits in the bitmap, return -1.
	 */
	return (-1);
}

#if 0
/*
 * Set the specified bit in the given bitmap.
 */
/*ARGSUSED*/
STATIC void
xfs_buf_item_set_bit(
	uint	*map,
	uint	size,
	uint	bit)
{
	uint	*wordp;
	int	word_bit;

	wordp = map + (bit >> BIT_TO_WORD_SHIFT);
	word_bit = bit & (NBWORD - 1);

	*wordp |= 1 << word_bit;
}
#endif
		
/*
 * Return 1 if the buffer has some data that has been logged (at any
 * point, not just the current transaction) and 0 if not.
 */
uint
xfs_buf_item_dirty(
	xfs_buf_log_item_t	*bip)
{
	return (bip->bli_flags & XFS_BLI_DIRTY);
}

/*
 * This is called when the buf log item is no longer needed.  It should
 * free the buf log item associated with the given buffer and clear
 * the buffer's pointer to the buf log item.  If there are no more
 * items in the list, clear the b_iodone field of the buffer (see
 * xfs_buf_attach_iodone() below).
 */
void
xfs_buf_item_relse(
	xfs_buf_t	*bp)
{
	xfs_buf_log_item_t	*bip;

	buftrace("XFS_RELSE", bp);
	bip = XFS_BUF_FSPRIVATE(bp, xfs_buf_log_item_t*);
	XFS_BUF_SET_FSPRIVATE(bp, bip->bli_item.li_bio_list);
	if ((XFS_BUF_FSPRIVATE(bp, void *) == NULL) &&
	    (XFS_BUF_IODONE_FUNC(bp) != NULL)) {
		ASSERT((XFS_BUF_ISUNINITIAL(bp)) == 0);
		XFS_BUF_CLR_IODONE_FUNC(bp);
	}

#ifdef XFS_TRANS_DEBUG
	kmem_free(bip->bli_orig, XFS_BUF_COUNT(bp));
	bip->bli_orig = NULL;
	kmem_free(bip->bli_logged, XFS_BUF_COUNT(bp) / NBBY);
	bip->bli_logged = NULL;
#endif /* XFS_TRANS_DEBUG */

#ifdef XFS_BLI_TRACE
	ktrace_free(bip->bli_trace);
#endif
	kmem_zone_free(xfs_buf_item_zone, bip);
}


/*
 * Add the given log item with it's callback to the list of callbacks
 * to be called when the buffer's I/O completes.  If it is not set
 * already, set the buffer's b_iodone() routine to be
 * xfs_buf_iodone_callbacks() and link the log item into the list of
 * items rooted at b_fsprivate.  Items are always added as the second
 * entry in the list if there is a first, because the buf item code
 * assumes that the buf log item is first.
 */
void
xfs_buf_attach_iodone(
	xfs_buf_t	*bp,
	void		(*cb)(xfs_buf_t *, xfs_log_item_t *),
	xfs_log_item_t	*lip)
{
	xfs_log_item_t	*head_lip;

	ASSERT(XFS_BUF_ISBUSY(bp)); 
	ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);

	lip->li_cb = cb;
	if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
		head_lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
		lip->li_bio_list = head_lip->li_bio_list;
		head_lip->li_bio_list = lip;
	} else {
		XFS_BUF_SET_FSPRIVATE(bp, lip);
	}

	ASSERT((XFS_BUF_IODONE_FUNC(bp) == xfs_buf_iodone_callbacks) ||
	       (XFS_BUF_IODONE_FUNC(bp) == NULL));
	XFS_BUF_SET_IODONE_FUNC(bp, xfs_buf_iodone_callbacks);
}

STATIC void
xfs_buf_do_callbacks(
	xfs_buf_t		*bp,
	xfs_log_item_t	*lip)
{
	xfs_log_item_t	*nlip;

	while (lip != NULL) {
		nlip = lip->li_bio_list;
		ASSERT(lip->li_cb != NULL);
		/*
		 * Clear the next pointer so we don't have any
		 * confusion if the item is added to another buf.
		 * Don't touch the log item after calling its
		 * callback, because it could have freed itself.
		 */
		lip->li_bio_list = NULL;
		lip->li_cb(bp, lip);
		lip = nlip;
	}
}
		       
/*
 * This is the iodone() function for buffers which have had callbacks
 * attached to them by xfs_buf_attach_iodone().  It should remove each
 * log item from the buffer's list and call the callback of each in turn.
 * When done, the buffer's fsprivate field is set to NULL and the buffer
 * is unlocked with a call to iodone().
 */
void
xfs_buf_iodone_callbacks(
	xfs_buf_t	*bp)
{
	xfs_log_item_t	*lip;
	static time_t	lasttime;
	static dev_t	lastdev;
	xfs_mount_t	*mp;

	ASSERT(XFS_BUF_FSPRIVATE(bp, void *) != NULL);
	lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);

	if (XFS_BUF_GETERROR(bp) != 0) {
		/*
		 * If we've already decided to shutdown the filesystem
		 * because of IO errors, there's no point in giving this
		 * a retry.
		 */ 
		mp = lip->li_mountp;
		if (XFS_FORCED_SHUTDOWN(mp)) {
			ASSERT(XFS_BUF_TARGET(bp) == mp->m_dev);
			XFS_BUF_SUPER_STALE(bp);
			buftrace("BUF_IODONE_CB", bp);
			xfs_buf_do_callbacks(bp, lip);
			XFS_BUF_SET_FSPRIVATE(bp, NULL);
			XFS_BUF_CLR_IODONE_FUNC(bp);

			/*
			 * XFS_SHUT flag gets set when we go thru the
			 * entire buffer cache and deliberately start
			 * throwing away delayed write buffers.
			 * Since there's no biowait done on those,
			 * we should just brelse them.
			 */
			if (XFS_BUF_ISSHUT(bp)) {
			    XFS_BUF_UNSHUT(bp);
				xfs_buf_relse(bp);
			} else {
			  xfs_biodone(bp);
			}
			
			return;
		}

		if ((XFS_BUF_TARGET(bp) != lastdev) ||
		    ((lbolt - lasttime) > 500)) {
			prdev("XFS write error in file system meta-data "
			      "block 0x%x in %s",
			      (int)XFS_BUF_TARGET(bp), XFS_BUF_ADDR(bp), 
			      mp->m_fsname);
			lasttime = lbolt;
		}
		lastdev = XFS_BUF_TARGET(bp);

		if (XFS_BUF_ISASYNC(bp)) {
			/*
			 * If the write was asynchronous then noone will be
			 * looking for the error.  Clear the error state
			 * and write the buffer out again delayed write.
			 *
			 * XXXsup This is OK, so long as we catch these
			 * before we start the umount; we don't want these
			 * DELWRI metadata bufs to be hanging around.
			 */
		  XFS_BUF_ERROR(bp,0); /* errno of 0 unsets the flag */

			if (!(XFS_BUF_ISSTALE(bp))) {
				XFS_BUF_DELAYWRITE(bp);
				XFS_BUF_DONE(bp);
				XFS_BUF_SET_START(bp);
			}
			ASSERT(XFS_BUF_IODONE_FUNC(bp));
			buftrace("BUF_IODONE ASYNC", bp);
			xfs_buf_relse(bp);
		} else {
			/*
			 * If the write of the buffer was not asynchronous,
			 * then we want to make sure to return the error
			 * to the caller of bwrite().  Because of this we
			 * cannot clear the B_ERROR state at this point.
			 * Instead we install a callback function that
			 * will be called when the buffer is released, and
			 * that routine will clear the error state and
			 * set the buffer to be written out again after
			 * some delay.
			 */
			/* We actually overwrite the existing b-relse
			   function at times, but we're gonna be shutting down
			   anyway. */
			XFS_BUF_SET_BRELSE_FUNC(bp,xfs_buf_error_relse);
			XFS_BUF_DONE(bp);
			XFS_BUF_V_IODONESEMA(bp);
		}
		return;
	}
#ifdef XFSERRORDEBUG
	buftrace("XFS BUFCB NOERR", bp);
#endif
	xfs_buf_do_callbacks(bp, lip);
	XFS_BUF_SET_FSPRIVATE(bp, NULL);
	XFS_BUF_CLR_IODONE_FUNC(bp);
	xfs_biodone(bp);
}

/*
 * This is a callback routine attached to a buffer which gets an error
 * when being written out synchronously. 
 */
STATIC void
xfs_buf_error_relse(
	xfs_buf_t	*bp)
{
	xfs_log_item_t 	*lip;
	xfs_mount_t	*mp;

	lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
	mp = (xfs_mount_t *)lip->li_mountp;
	ASSERT(XFS_BUF_TARGET(bp) == mp->m_dev);

	XFS_BUF_STALE(bp);
	XFS_BUF_DONE(bp);
	XFS_BUF_UNDELAYWRITE(bp);
	XFS_BUF_ERROR(bp,0)
    xfs_buftrace("BUF_ERROR_RELSE", bp);
	if (! XFS_FORCED_SHUTDOWN(mp)) 		
		xfs_force_shutdown(mp, XFS_METADATA_IO_ERROR);
	/*
	 * We have to unpin the pinned buffers so do the
	 * callbacks.
	 */
	xfs_buf_do_callbacks(bp, lip);
	XFS_BUF_SET_FSPRIVATE(bp, NULL);
	XFS_BUF_CLR_IODONE_FUNC(bp);
	XFS_BUF_SET_BRELSE_FUNC(bp,NULL);
	xfs_buf_relse(bp);
	return;

}


/*
 * This is the iodone() function for buffers which have been
 * logged.  It is called when they are eventually flushed out.
 * It should remove the buf item from the AIL, and free the buf item.
 * It is called by xfs_buf_iodone_callbacks() above which will take
 * care of cleaning up the buffer itself.
 */ 
/* ARGSUSED */
void
xfs_buf_iodone(
	xfs_buf_t			*bp,
	xfs_buf_log_item_t	*bip)
{
	struct xfs_mount	*mp;
	SPLDECL(s);

	ASSERT(bip->bli_buf == bp);

	mp = bip->bli_item.li_mountp;

	/*
	 * If we are forcibly shutting down, this may well be
	 * off the AIL already. That's because we simulate the
	 * log-committed callbacks to unpin these buffers. Or we may never
	 * have put this item on AIL because of the transaction was
	 * aborted forcibly. xfs_trans_delete_ail() takes care of these.
	 *
	 * Either way, AIL is useless if we're forcing a shutdown.
	 */
	AIL_LOCK(mp,s);
	/*
	 * xfs_trans_delete_ail() drops the AIL lock.
	 */
	xfs_trans_delete_ail(mp, (xfs_log_item_t *)bip, s);

#ifdef XFS_TRANS_DEBUG
	kmem_free(bip->bli_orig, XFS_BUF_COUNT(bp));
	bip->bli_orig = NULL;
	kmem_free(bip->bli_logged, XFS_BUF_COUNT(bp) / NBBY);
	bip->bli_logged = NULL;
#endif /* XFS_TRANS_DEBUG */

#ifdef XFS_BLI_TRACE
	ktrace_free(bip->bli_trace);
#endif
	kmem_zone_free(xfs_buf_item_zone, bip);
}

#if defined(XFS_BLI_TRACE)
void
xfs_buf_item_trace(
	char			*id,
	xfs_buf_log_item_t	*bip)
{
	xfs_buf_t	*bp;
	ASSERT(bip->bli_trace != NULL);

	bp = bip->bli_buf;
	ktrace_enter(bip->bli_trace,
		     (void *)id,
		     (void *)bip->bli_buf,
		     (void *)((unsigned long)bip->bli_flags),
		     (void *)((unsigned long)bip->bli_recur),
		     (void *)((unsigned long)bip->bli_refcount),
		     (void *)XFS_BUF_ADDR(bp),
		     (void *)((unsigned long)XFS_BUF_COUNT(bp)),
		     (void *)((unsigned long)(0xFFFFFFFF & (XFS_BFLAGS(bp) >> 32))),
		     (void *)((unsigned long)(0xFFFFFFFF & XFS_BFLAGS(bp))),
		     XFS_BUF_FSPRIVATE(bp, void *),
		     XFS_BUF_FSPRIVATE2(bp, void *),
		     (void *)((unsigned long)bp->b_pincount),
		     (void *)XFS_BUF_IODONE_FUNC(bp),
		     (void *)((unsigned long)(XFS_BUF_VALUSEMA(bp))),
		     (void *)bip->bli_item.li_desc,
		     (void *)((unsigned long)bip->bli_item.li_flags));
}
#endif /* XFS_BLI_TRACE */