fs/xfs/xfs_trans_item.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (c) 2000-2002,2005 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.
  *
  * This program is distributed in the hope that it would 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.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 #include "xfs.h"
 #include "xfs_fs.h"
 #include "xfs_types.h"
 #include "xfs_log.h"
 #include "xfs_inum.h"
 #include "xfs_trans.h"
 #include "xfs_trans_priv.h"

 STATIC int	xfs_trans_unlock_chunk(xfs_log_item_chunk_t *,
 					int, int, xfs_lsn_t);

 /*
  * This is called to add the given log item to the transaction's
  * list of log items.  It must find a free log item descriptor
  * or allocate a new one and add the item to that descriptor.
  * The function returns a pointer to item descriptor used to point
  * to the new item.  The log item will now point to its new descriptor
  * with its li_desc field.
  */
 xfs_log_item_desc_t *
 xfs_trans_add_item(xfs_trans_t *tp, xfs_log_item_t *lip)
 {
 	xfs_log_item_desc_t	*lidp;
 	xfs_log_item_chunk_t	*licp;
 	int			i=0;

 	/*
 	 * If there are no free descriptors, allocate a new chunk
 	 * of them and put it at the front of the chunk list.
 	 */
 	if (tp->t_items_free == 0) {
 		licp = (xfs_log_item_chunk_t*)
 		       kmem_alloc(sizeof(xfs_log_item_chunk_t), KM_SLEEP);
 		ASSERT(licp != NULL);
 		/*
 		 * Initialize the chunk, and then
 		 * claim the first slot in the newly allocated chunk.
 		 */
 		XFS_LIC_INIT(licp);
 		XFS_LIC_CLAIM(licp, 0);
 		licp->lic_unused = 1;
 		XFS_LIC_INIT_SLOT(licp, 0);
 		lidp = XFS_LIC_SLOT(licp, 0);

 		/*
 		 * Link in the new chunk and update the free count.
 		 */
 		licp->lic_next = tp->t_items.lic_next;
 		tp->t_items.lic_next = licp;
 		tp->t_items_free = XFS_LIC_NUM_SLOTS - 1;

 		/*
 		 * Initialize the descriptor and the generic portion
 		 * of the log item.
 		 *
 		 * Point the new slot at this item and return it.
 		 * Also point the log item at its currently active
 		 * descriptor and set the item's mount pointer.
 		 */
 		lidp->lid_item = lip;
 		lidp->lid_flags = 0;
 		lidp->lid_size = 0;
 		lip->li_desc = lidp;
 		lip->li_mountp = tp->t_mountp;
 		return lidp;
 	}

 	/*
 	 * Find the free descriptor. It is somewhere in the chunklist
 	 * of descriptors.
 	 */
 	licp = &tp->t_items;
 	while (licp != NULL) {
 		if (XFS_LIC_VACANCY(licp)) {
 			if (licp->lic_unused <= XFS_LIC_MAX_SLOT) {
 				i = licp->lic_unused;
 				ASSERT(XFS_LIC_ISFREE(licp, i));
 				break;
 			}
 			for (i = 0; i <= XFS_LIC_MAX_SLOT; i++) {
 				if (XFS_LIC_ISFREE(licp, i))
 					break;
 			}
 			ASSERT(i <= XFS_LIC_MAX_SLOT);
 			break;
 		}
 		licp = licp->lic_next;
 	}
 	ASSERT(licp != NULL);
 	/*
 	 * If we find a free descriptor, claim it,
 	 * initialize it, and return it.
 	 */
 	XFS_LIC_CLAIM(licp, i);
 	if (licp->lic_unused <= i) {
 		licp->lic_unused = i + 1;
 		XFS_LIC_INIT_SLOT(licp, i);
 	}
 	lidp = XFS_LIC_SLOT(licp, i);
 	tp->t_items_free--;
 	lidp->lid_item = lip;
 	lidp->lid_flags = 0;
 	lidp->lid_size = 0;
 	lip->li_desc = lidp;
 	lip->li_mountp = tp->t_mountp;
 	return lidp;
 }

 /*
  * Free the given descriptor.
  *
  * This requires setting the bit in the chunk's free mask corresponding
  * to the given slot.
  */
 void
 xfs_trans_free_item(xfs_trans_t	*tp, xfs_log_item_desc_t *lidp)
 {
 	uint			slot;
 	xfs_log_item_chunk_t	*licp;
 	xfs_log_item_chunk_t	**licpp;

 	slot = XFS_LIC_DESC_TO_SLOT(lidp);
 	licp = XFS_LIC_DESC_TO_CHUNK(lidp);
 	XFS_LIC_RELSE(licp, slot);
 	lidp->lid_item->li_desc = NULL;
 	tp->t_items_free++;

 	/*
 	 * If there are no more used items in the chunk and this is not
 	 * the chunk embedded in the transaction structure, then free
 	 * the chunk. First pull it from the chunk list and then
 	 * free it back to the heap.  We didn't bother with a doubly
 	 * linked list here because the lists should be very short
 	 * and this is not a performance path.  It's better to save
 	 * the memory of the extra pointer.
 	 *
 	 * Also decrement the transaction structure's count of free items
 	 * by the number in a chunk since we are freeing an empty chunk.
 	 */
 	if (XFS_LIC_ARE_ALL_FREE(licp) && (licp != &(tp->t_items))) {
 		licpp = &(tp->t_items.lic_next);
 		while (*licpp != licp) {
 			ASSERT(*licpp != NULL);
 			licpp = &((*licpp)->lic_next);
 		}
 		*licpp = licp->lic_next;
 		kmem_free(licp);
 		tp->t_items_free -= XFS_LIC_NUM_SLOTS;
 	}
 }

 /*
  * This is called to find the descriptor corresponding to the given
  * log item.  It returns a pointer to the descriptor.
  * The log item MUST have a corresponding descriptor in the given
  * transaction.  This routine does not return NULL, it panics.
  *
  * The descriptor pointer is kept in the log item's li_desc field.
  * Just return it.
  */
 /*ARGSUSED*/
 xfs_log_item_desc_t *
 xfs_trans_find_item(xfs_trans_t	*tp, xfs_log_item_t *lip)
 {
 	ASSERT(lip->li_desc != NULL);

 	return lip->li_desc;
 }


 /*
  * Return a pointer to the first descriptor in the chunk list.
  * This does not return NULL if there are none, it panics.
  *
  * The first descriptor must be in either the first or second chunk.
  * This is because the only chunk allowed to be empty is the first.
  * All others are freed when they become empty.
  *
  * At some point this and xfs_trans_next_item() should be optimized
  * to quickly look at the mask to determine if there is anything to
  * look at.
  */
 xfs_log_item_desc_t *
 xfs_trans_first_item(xfs_trans_t *tp)
 {
 	xfs_log_item_chunk_t	*licp;
 	int			i;

 	licp = &tp->t_items;
 	/*
 	 * If it's not in the first chunk, skip to the second.
 	 */
 	if (XFS_LIC_ARE_ALL_FREE(licp)) {
 		licp = licp->lic_next;
 	}

 	/*
 	 * Return the first non-free descriptor in the chunk.
 	 */
 	ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
 	for (i = 0; i < licp->lic_unused; i++) {
 		if (XFS_LIC_ISFREE(licp, i)) {
 			continue;
 		}

 		return XFS_LIC_SLOT(licp, i);
 	}
 	cmn_err(CE_WARN, "xfs_trans_first_item() -- no first item");
 	return NULL;
 }


 /*
  * Given a descriptor, return the next descriptor in the chunk list.
  * This returns NULL if there are no more used descriptors in the list.
  *
  * We do this by first locating the chunk in which the descriptor resides,
  * and then scanning forward in the chunk and the list for the next
  * used descriptor.
  */
 /*ARGSUSED*/
 xfs_log_item_desc_t *
 xfs_trans_next_item(xfs_trans_t *tp, xfs_log_item_desc_t *lidp)
 {
 	xfs_log_item_chunk_t	*licp;
 	int			i;

 	licp = XFS_LIC_DESC_TO_CHUNK(lidp);

 	/*
 	 * First search the rest of the chunk. The for loop keeps us
 	 * from referencing things beyond the end of the chunk.
 	 */
 	for (i = (int)XFS_LIC_DESC_TO_SLOT(lidp) + 1; i < licp->lic_unused; i++) {
 		if (XFS_LIC_ISFREE(licp, i)) {
 			continue;
 		}

 		return XFS_LIC_SLOT(licp, i);
 	}

 	/*
 	 * Now search the next chunk.  It must be there, because the
 	 * next chunk would have been freed if it were empty.
 	 * If there is no next chunk, return NULL.
 	 */
 	if (licp->lic_next == NULL) {
 		return NULL;
 	}

 	licp = licp->lic_next;
 	ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
 	for (i = 0; i < licp->lic_unused; i++) {
 		if (XFS_LIC_ISFREE(licp, i)) {
 			continue;
 		}

 		return XFS_LIC_SLOT(licp, i);
 	}
 	ASSERT(0);
 	/* NOTREACHED */
 	return NULL; /* keep gcc quite */
 }

 /*
  * This is called to unlock all of the items of a transaction and to free
  * all the descriptors of that transaction.
  *
  * It walks the list of descriptors and unlocks each item.  It frees
  * each chunk except that embedded in the transaction as it goes along.
  */
 void
 xfs_trans_free_items(
 	xfs_trans_t	*tp,
 	int		flags)
 {
 	xfs_log_item_chunk_t	*licp;
 	xfs_log_item_chunk_t	*next_licp;
 	int			abort;

 	abort = flags & XFS_TRANS_ABORT;
 	licp = &tp->t_items;
 	/*
 	 * Special case the embedded chunk so we don't free it below.
 	 */
 	if (!XFS_LIC_ARE_ALL_FREE(licp)) {
 		(void) xfs_trans_unlock_chunk(licp, 1, abort, NULLCOMMITLSN);
 		XFS_LIC_ALL_FREE(licp);
 		licp->lic_unused = 0;
 	}
 	licp = licp->lic_next;

 	/*
 	 * Unlock each item in each chunk and free the chunks.
 	 */
 	while (licp != NULL) {
 		ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
 		(void) xfs_trans_unlock_chunk(licp, 1, abort, NULLCOMMITLSN);
 		next_licp = licp->lic_next;
 		kmem_free(licp);
 		licp = next_licp;
 	}

 	/*
 	 * Reset the transaction structure's free item count.
 	 */
 	tp->t_items_free = XFS_LIC_NUM_SLOTS;
 	tp->t_items.lic_next = NULL;
 }


 /*
  * This is called to unlock the items associated with a transaction.
  * Items which were not logged should be freed.
  * Those which were logged must still be tracked so they can be unpinned
  * when the transaction commits.
  */
 void
 xfs_trans_unlock_items(xfs_trans_t *tp, xfs_lsn_t commit_lsn)
 {
 	xfs_log_item_chunk_t	*licp;
 	xfs_log_item_chunk_t	*next_licp;
 	xfs_log_item_chunk_t	**licpp;
 	int			freed;

 	freed = 0;
 	licp = &tp->t_items;

 	/*
 	 * Special case the embedded chunk so we don't free.
 	 */
 	if (!XFS_LIC_ARE_ALL_FREE(licp)) {
 		freed = xfs_trans_unlock_chunk(licp, 0, 0, commit_lsn);
 	}
 	licpp = &(tp->t_items.lic_next);
 	licp = licp->lic_next;

 	/*
 	 * Unlock each item in each chunk, free non-dirty descriptors,
 	 * and free empty chunks.
 	 */
 	while (licp != NULL) {
 		ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
 		freed += xfs_trans_unlock_chunk(licp, 0, 0, commit_lsn);
 		next_licp = licp->lic_next;
 		if (XFS_LIC_ARE_ALL_FREE(licp)) {
 			*licpp = next_licp;
 			kmem_free(licp);
 			freed -= XFS_LIC_NUM_SLOTS;
 		} else {
 			licpp = &(licp->lic_next);
 		}
 		ASSERT(*licpp == next_licp);
 		licp = next_licp;
 	}

 	/*
 	 * Fix the free descriptor count in the transaction.
 	 */
 	tp->t_items_free += freed;
 }

 /*
  * Unlock each item pointed to by a descriptor in the given chunk.
  * Stamp the commit lsn into each item if necessary.
  * Free descriptors pointing to items which are not dirty if freeing_chunk
  * is zero. If freeing_chunk is non-zero, then we need to unlock all
  * items in the chunk.
  *
  * Return the number of descriptors freed.
  */
 STATIC int
 xfs_trans_unlock_chunk(
 	xfs_log_item_chunk_t	*licp,
 	int			freeing_chunk,
 	int			abort,
 	xfs_lsn_t		commit_lsn)
 {
 	xfs_log_item_desc_t	*lidp;
 	xfs_log_item_t		*lip;
 	int			i;
 	int			freed;

 	freed = 0;
 	lidp = licp->lic_descs;
 	for (i = 0; i < licp->lic_unused; i++, lidp++) {
 		if (XFS_LIC_ISFREE(licp, i)) {
 			continue;
 		}
 		lip = lidp->lid_item;
 		lip->li_desc = NULL;

 		if (commit_lsn != NULLCOMMITLSN)
 			IOP_COMMITTING(lip, commit_lsn);
 		if (abort)
 			lip->li_flags |= XFS_LI_ABORTED;
 		IOP_UNLOCK(lip);

 		/*
 		 * Free the descriptor if the item is not dirty
 		 * within this transaction and the caller is not
 		 * going to just free the entire thing regardless.
 		 */
 		if (!(freeing_chunk) &&
 		    (!(lidp->lid_flags & XFS_LID_DIRTY) || abort)) {
 			XFS_LIC_RELSE(licp, i);
 			freed++;
 		}
 	}

 	return freed;
 }


 /*
  * This is called to add the given busy item to the transaction's
  * list of busy items.  It must find a free busy item descriptor
  * or allocate a new one and add the item to that descriptor.
  * The function returns a pointer to busy descriptor used to point
  * to the new busy entry.  The log busy entry will now point to its new
  * descriptor with its ???? field.
  */
 xfs_log_busy_slot_t *
 xfs_trans_add_busy(xfs_trans_t *tp, xfs_agnumber_t ag, xfs_extlen_t idx)
 {
 	xfs_log_busy_chunk_t	*lbcp;
 	xfs_log_busy_slot_t	*lbsp;
 	int			i=0;

 	/*
 	 * If there are no free descriptors, allocate a new chunk
 	 * of them and put it at the front of the chunk list.
 	 */
 	if (tp->t_busy_free == 0) {
 		lbcp = (xfs_log_busy_chunk_t*)
 		       kmem_alloc(sizeof(xfs_log_busy_chunk_t), KM_SLEEP);
 		ASSERT(lbcp != NULL);
 		/*
 		 * Initialize the chunk, and then
 		 * claim the first slot in the newly allocated chunk.
 		 */
 		XFS_LBC_INIT(lbcp);
 		XFS_LBC_CLAIM(lbcp, 0);
 		lbcp->lbc_unused = 1;
 		lbsp = XFS_LBC_SLOT(lbcp, 0);

 		/*
 		 * Link in the new chunk and update the free count.
 		 */
 		lbcp->lbc_next = tp->t_busy.lbc_next;
 		tp->t_busy.lbc_next = lbcp;
 		tp->t_busy_free = XFS_LIC_NUM_SLOTS - 1;

 		/*
 		 * Initialize the descriptor and the generic portion
 		 * of the log item.
 		 *
 		 * Point the new slot at this item and return it.
 		 * Also point the log item at its currently active
 		 * descriptor and set the item's mount pointer.
 		 */
 		lbsp->lbc_ag = ag;
 		lbsp->lbc_idx = idx;
 		return lbsp;
 	}

 	/*
 	 * Find the free descriptor. It is somewhere in the chunklist
 	 * of descriptors.
 	 */
 	lbcp = &tp->t_busy;
 	while (lbcp != NULL) {
 		if (XFS_LBC_VACANCY(lbcp)) {
 			if (lbcp->lbc_unused <= XFS_LBC_MAX_SLOT) {
 				i = lbcp->lbc_unused;
 				break;
 			} else {
 				/* out-of-order vacancy */
 				cmn_err(CE_DEBUG, "OOO vacancy lbcp 0x%p\n", lbcp);
 				ASSERT(0);
 			}
 		}
 		lbcp = lbcp->lbc_next;
 	}
 	ASSERT(lbcp != NULL);
 	/*
 	 * If we find a free descriptor, claim it,
 	 * initialize it, and return it.
 	 */
 	XFS_LBC_CLAIM(lbcp, i);
 	if (lbcp->lbc_unused <= i) {
 		lbcp->lbc_unused = i + 1;
 	}
 	lbsp = XFS_LBC_SLOT(lbcp, i);
 	tp->t_busy_free--;
 	lbsp->lbc_ag = ag;
 	lbsp->lbc_idx = idx;
 	return lbsp;
 }


 /*
  * xfs_trans_free_busy
  * Free all of the busy lists from a transaction
  */
 void
 xfs_trans_free_busy(xfs_trans_t *tp)
 {
 	xfs_log_busy_chunk_t	*lbcp;
 	xfs_log_busy_chunk_t	*lbcq;

 	lbcp = tp->t_busy.lbc_next;
 	while (lbcp != NULL) {
 		lbcq = lbcp->lbc_next;
 		kmem_free(lbcp);
 		lbcp = lbcq;
 	}

 	XFS_LBC_INIT(&tp->t_busy);
 	tp->t_busy.lbc_unused = 0;
 }
	/*
	* Copyright (c) 2000-2002,2005 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.
	*
	* This program is distributed in the hope that it would 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	*/
	#include "xfs.h"
	#include "xfs_fs.h"
	#include "xfs_types.h"
	#include "xfs_log.h"
	#include "xfs_inum.h"
	#include "xfs_trans.h"
	#include "xfs_trans_priv.h"

	STATIC int xfs_trans_unlock_chunk(xfs_log_item_chunk_t *,
	int, int, xfs_lsn_t);

	/*
	* This is called to add the given log item to the transaction's
	* list of log items. It must find a free log item descriptor
	* or allocate a new one and add the item to that descriptor.
	* The function returns a pointer to item descriptor used to point
	* to the new item. The log item will now point to its new descriptor
	* with its li_desc field.
	*/
	xfs_log_item_desc_t *
	xfs_trans_add_item(xfs_trans_t tp, xfs_log_item_t lip)
	{
	xfs_log_item_desc_t *lidp;
	xfs_log_item_chunk_t *licp;
	int i=0;

	/*
	* If there are no free descriptors, allocate a new chunk
	* of them and put it at the front of the chunk list.
	*/
	if (tp->t_items_free == 0) {
	licp = (xfs_log_item_chunk_t*)
	kmem_alloc(sizeof(xfs_log_item_chunk_t), KM_SLEEP);
	ASSERT(licp != NULL);
	/*
	* Initialize the chunk, and then
	* claim the first slot in the newly allocated chunk.
	*/
	XFS_LIC_INIT(licp);
	XFS_LIC_CLAIM(licp, 0);
	licp->lic_unused = 1;
	XFS_LIC_INIT_SLOT(licp, 0);
	lidp = XFS_LIC_SLOT(licp, 0);

	/*
	* Link in the new chunk and update the free count.
	*/
	licp->lic_next = tp->t_items.lic_next;
	tp->t_items.lic_next = licp;
	tp->t_items_free = XFS_LIC_NUM_SLOTS - 1;

	/*
	* Initialize the descriptor and the generic portion
	* of the log item.
	*
	* Point the new slot at this item and return it.
	* Also point the log item at its currently active
	* descriptor and set the item's mount pointer.
	*/
	lidp->lid_item = lip;
	lidp->lid_flags = 0;
	lidp->lid_size = 0;
	lip->li_desc = lidp;
	lip->li_mountp = tp->t_mountp;
	return lidp;
	}

	/*
	* Find the free descriptor. It is somewhere in the chunklist
	* of descriptors.
	*/
	licp = &tp->t_items;
	while (licp != NULL) {
	if (XFS_LIC_VACANCY(licp)) {
	if (licp->lic_unused <= XFS_LIC_MAX_SLOT) {
	i = licp->lic_unused;
	ASSERT(XFS_LIC_ISFREE(licp, i));
	break;
	}
	for (i = 0; i <= XFS_LIC_MAX_SLOT; i++) {
	if (XFS_LIC_ISFREE(licp, i))
	break;
	}
	ASSERT(i <= XFS_LIC_MAX_SLOT);
	break;
	}
	licp = licp->lic_next;
	}
	ASSERT(licp != NULL);
	/*
	* If we find a free descriptor, claim it,
	* initialize it, and return it.
	*/
	XFS_LIC_CLAIM(licp, i);
	if (licp->lic_unused <= i) {
	licp->lic_unused = i + 1;
	XFS_LIC_INIT_SLOT(licp, i);
	}
	lidp = XFS_LIC_SLOT(licp, i);
	tp->t_items_free--;
	lidp->lid_item = lip;
	lidp->lid_flags = 0;
	lidp->lid_size = 0;
	lip->li_desc = lidp;
	lip->li_mountp = tp->t_mountp;
	return lidp;
	}

	/*
	* Free the given descriptor.
	*
	* This requires setting the bit in the chunk's free mask corresponding
	* to the given slot.
	*/
	void
	xfs_trans_free_item(xfs_trans_t tp, xfs_log_item_desc_t lidp)
	{
	uint slot;
	xfs_log_item_chunk_t *licp;
	xfs_log_item_chunk_t **licpp;

	slot = XFS_LIC_DESC_TO_SLOT(lidp);
	licp = XFS_LIC_DESC_TO_CHUNK(lidp);
	XFS_LIC_RELSE(licp, slot);
	lidp->lid_item->li_desc = NULL;
	tp->t_items_free++;

	/*
	* If there are no more used items in the chunk and this is not
	* the chunk embedded in the transaction structure, then free
	* the chunk. First pull it from the chunk list and then
	* free it back to the heap. We didn't bother with a doubly
	* linked list here because the lists should be very short
	* and this is not a performance path. It's better to save
	* the memory of the extra pointer.
	*
	* Also decrement the transaction structure's count of free items
	* by the number in a chunk since we are freeing an empty chunk.
	*/
	if (XFS_LIC_ARE_ALL_FREE(licp) && (licp != &(tp->t_items))) {
	licpp = &(tp->t_items.lic_next);
	while (*licpp != licp) {
	ASSERT(*licpp != NULL);
	licpp = &((*licpp)->lic_next);
	}
	*licpp = licp->lic_next;
	kmem_free(licp);
	tp->t_items_free -= XFS_LIC_NUM_SLOTS;
	}
	}

	/*
	* This is called to find the descriptor corresponding to the given
	* log item. It returns a pointer to the descriptor.
	* The log item MUST have a corresponding descriptor in the given
	* transaction. This routine does not return NULL, it panics.
	*
	* The descriptor pointer is kept in the log item's li_desc field.
	* Just return it.
	*/
	/ARGSUSED/
	xfs_log_item_desc_t *
	xfs_trans_find_item(xfs_trans_t tp, xfs_log_item_t lip)
	{
	ASSERT(lip->li_desc != NULL);

	return lip->li_desc;
	}


	/*
	* Return a pointer to the first descriptor in the chunk list.
	* This does not return NULL if there are none, it panics.
	*
	* The first descriptor must be in either the first or second chunk.
	* This is because the only chunk allowed to be empty is the first.
	* All others are freed when they become empty.
	*
	* At some point this and xfs_trans_next_item() should be optimized
	* to quickly look at the mask to determine if there is anything to
	* look at.
	*/
	xfs_log_item_desc_t *
	xfs_trans_first_item(xfs_trans_t *tp)
	{
	xfs_log_item_chunk_t *licp;
	int i;

	licp = &tp->t_items;
	/*
	* If it's not in the first chunk, skip to the second.
	*/
	if (XFS_LIC_ARE_ALL_FREE(licp)) {
	licp = licp->lic_next;
	}

	/*
	* Return the first non-free descriptor in the chunk.
	*/
	ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
	for (i = 0; i < licp->lic_unused; i++) {
	if (XFS_LIC_ISFREE(licp, i)) {
	continue;
	}

	return XFS_LIC_SLOT(licp, i);
	}
	cmn_err(CE_WARN, "xfs_trans_first_item() -- no first item");
	return NULL;
	}


	/*
	* Given a descriptor, return the next descriptor in the chunk list.
	* This returns NULL if there are no more used descriptors in the list.
	*
	* We do this by first locating the chunk in which the descriptor resides,
	* and then scanning forward in the chunk and the list for the next
	* used descriptor.
	*/
	/ARGSUSED/
	xfs_log_item_desc_t *
	xfs_trans_next_item(xfs_trans_t tp, xfs_log_item_desc_t lidp)
	{
	xfs_log_item_chunk_t *licp;
	int i;

	licp = XFS_LIC_DESC_TO_CHUNK(lidp);

	/*
	* First search the rest of the chunk. The for loop keeps us
	* from referencing things beyond the end of the chunk.
	*/
	for (i = (int)XFS_LIC_DESC_TO_SLOT(lidp) + 1; i < licp->lic_unused; i++) {
	if (XFS_LIC_ISFREE(licp, i)) {
	continue;
	}

	return XFS_LIC_SLOT(licp, i);
	}

	/*
	* Now search the next chunk. It must be there, because the
	* next chunk would have been freed if it were empty.
	* If there is no next chunk, return NULL.
	*/
	if (licp->lic_next == NULL) {
	return NULL;
	}

	licp = licp->lic_next;
	ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
	for (i = 0; i < licp->lic_unused; i++) {
	if (XFS_LIC_ISFREE(licp, i)) {
	continue;
	}

	return XFS_LIC_SLOT(licp, i);
	}
	ASSERT(0);
	/* NOTREACHED */
	return NULL; /* keep gcc quite */
	}

	/*
	* This is called to unlock all of the items of a transaction and to free
	* all the descriptors of that transaction.
	*
	* It walks the list of descriptors and unlocks each item. It frees
	* each chunk except that embedded in the transaction as it goes along.
	*/
	void
	xfs_trans_free_items(
	xfs_trans_t *tp,
	int flags)
	{
	xfs_log_item_chunk_t *licp;
	xfs_log_item_chunk_t *next_licp;
	int abort;

	abort = flags & XFS_TRANS_ABORT;
	licp = &tp->t_items;
	/*
	* Special case the embedded chunk so we don't free it below.
	*/
	if (!XFS_LIC_ARE_ALL_FREE(licp)) {
	(void) xfs_trans_unlock_chunk(licp, 1, abort, NULLCOMMITLSN);
	XFS_LIC_ALL_FREE(licp);
	licp->lic_unused = 0;
	}
	licp = licp->lic_next;

	/*
	* Unlock each item in each chunk and free the chunks.
	*/
	while (licp != NULL) {
	ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
	(void) xfs_trans_unlock_chunk(licp, 1, abort, NULLCOMMITLSN);
	next_licp = licp->lic_next;
	kmem_free(licp);
	licp = next_licp;
	}

	/*
	* Reset the transaction structure's free item count.
	*/
	tp->t_items_free = XFS_LIC_NUM_SLOTS;
	tp->t_items.lic_next = NULL;
	}



	/*
	* This is called to unlock the items associated with a transaction.
	* Items which were not logged should be freed.
	* Those which were logged must still be tracked so they can be unpinned
	* when the transaction commits.
	*/
	void
	xfs_trans_unlock_items(xfs_trans_t *tp, xfs_lsn_t commit_lsn)
	{
	xfs_log_item_chunk_t *licp;
	xfs_log_item_chunk_t *next_licp;
	xfs_log_item_chunk_t **licpp;
	int freed;

	freed = 0;
	licp = &tp->t_items;

	/*
	* Special case the embedded chunk so we don't free.
	*/
	if (!XFS_LIC_ARE_ALL_FREE(licp)) {
	freed = xfs_trans_unlock_chunk(licp, 0, 0, commit_lsn);
	}
	licpp = &(tp->t_items.lic_next);
	licp = licp->lic_next;

	/*
	* Unlock each item in each chunk, free non-dirty descriptors,
	* and free empty chunks.
	*/
	while (licp != NULL) {
	ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
	freed += xfs_trans_unlock_chunk(licp, 0, 0, commit_lsn);
	next_licp = licp->lic_next;
	if (XFS_LIC_ARE_ALL_FREE(licp)) {
	*licpp = next_licp;
	kmem_free(licp);
	freed -= XFS_LIC_NUM_SLOTS;
	} else {
	licpp = &(licp->lic_next);
	}
	ASSERT(*licpp == next_licp);
	licp = next_licp;
	}

	/*
	* Fix the free descriptor count in the transaction.
	*/
	tp->t_items_free += freed;
	}

	/*
	* Unlock each item pointed to by a descriptor in the given chunk.
	* Stamp the commit lsn into each item if necessary.
	* Free descriptors pointing to items which are not dirty if freeing_chunk
	* is zero. If freeing_chunk is non-zero, then we need to unlock all
	* items in the chunk.
	*
	* Return the number of descriptors freed.
	*/
	STATIC int
	xfs_trans_unlock_chunk(
	xfs_log_item_chunk_t *licp,
	int freeing_chunk,
	int abort,
	xfs_lsn_t commit_lsn)
	{
	xfs_log_item_desc_t *lidp;
	xfs_log_item_t *lip;
	int i;
	int freed;

	freed = 0;
	lidp = licp->lic_descs;
	for (i = 0; i < licp->lic_unused; i++, lidp++) {
	if (XFS_LIC_ISFREE(licp, i)) {
	continue;
	}
	lip = lidp->lid_item;
	lip->li_desc = NULL;

	if (commit_lsn != NULLCOMMITLSN)
	IOP_COMMITTING(lip, commit_lsn);
	if (abort)
	lip->li_flags \|= XFS_LI_ABORTED;
	IOP_UNLOCK(lip);

	/*
	* Free the descriptor if the item is not dirty
	* within this transaction and the caller is not
	* going to just free the entire thing regardless.
	*/
	if (!(freeing_chunk) &&
	(!(lidp->lid_flags & XFS_LID_DIRTY) \|\| abort)) {
	XFS_LIC_RELSE(licp, i);
	freed++;
	}
	}

	return freed;
	}


	/*
	* This is called to add the given busy item to the transaction's
	* list of busy items. It must find a free busy item descriptor
	* or allocate a new one and add the item to that descriptor.
	* The function returns a pointer to busy descriptor used to point
	* to the new busy entry. The log busy entry will now point to its new
	* descriptor with its ???? field.
	*/
	xfs_log_busy_slot_t *
	xfs_trans_add_busy(xfs_trans_t *tp, xfs_agnumber_t ag, xfs_extlen_t idx)
	{
	xfs_log_busy_chunk_t *lbcp;
	xfs_log_busy_slot_t *lbsp;
	int i=0;

	/*
	* If there are no free descriptors, allocate a new chunk
	* of them and put it at the front of the chunk list.
	*/
	if (tp->t_busy_free == 0) {
	lbcp = (xfs_log_busy_chunk_t*)
	kmem_alloc(sizeof(xfs_log_busy_chunk_t), KM_SLEEP);
	ASSERT(lbcp != NULL);
	/*
	* Initialize the chunk, and then
	* claim the first slot in the newly allocated chunk.
	*/
	XFS_LBC_INIT(lbcp);
	XFS_LBC_CLAIM(lbcp, 0);
	lbcp->lbc_unused = 1;
	lbsp = XFS_LBC_SLOT(lbcp, 0);

	/*
	* Link in the new chunk and update the free count.
	*/
	lbcp->lbc_next = tp->t_busy.lbc_next;
	tp->t_busy.lbc_next = lbcp;
	tp->t_busy_free = XFS_LIC_NUM_SLOTS - 1;

	/*
	* Initialize the descriptor and the generic portion
	* of the log item.
	*
	* Point the new slot at this item and return it.
	* Also point the log item at its currently active
	* descriptor and set the item's mount pointer.
	*/
	lbsp->lbc_ag = ag;
	lbsp->lbc_idx = idx;
	return lbsp;
	}

	/*
	* Find the free descriptor. It is somewhere in the chunklist
	* of descriptors.
	*/
	lbcp = &tp->t_busy;
	while (lbcp != NULL) {
	if (XFS_LBC_VACANCY(lbcp)) {
	if (lbcp->lbc_unused <= XFS_LBC_MAX_SLOT) {
	i = lbcp->lbc_unused;
	break;
	} else {
	/* out-of-order vacancy */
	cmn_err(CE_DEBUG, "OOO vacancy lbcp 0x%p\n", lbcp);
	ASSERT(0);
	}
	}
	lbcp = lbcp->lbc_next;
	}
	ASSERT(lbcp != NULL);
	/*
	* If we find a free descriptor, claim it,
	* initialize it, and return it.
	*/
	XFS_LBC_CLAIM(lbcp, i);
	if (lbcp->lbc_unused <= i) {
	lbcp->lbc_unused = i + 1;
	}
	lbsp = XFS_LBC_SLOT(lbcp, i);
	tp->t_busy_free--;
	lbsp->lbc_ag = ag;
	lbsp->lbc_idx = idx;
	return lbsp;
	}


	/*
	* xfs_trans_free_busy
	* Free all of the busy lists from a transaction
	*/
	void
	xfs_trans_free_busy(xfs_trans_t *tp)
	{
	xfs_log_busy_chunk_t *lbcp;
	xfs_log_busy_chunk_t *lbcq;

	lbcp = tp->t_busy.lbc_next;
	while (lbcp != NULL) {
	lbcq = lbcp->lbc_next;
	kmem_free(lbcp);
	lbcp = lbcq;
	}

	XFS_LBC_INIT(&tp->t_busy);
	tp->t_busy.lbc_unused = 0;
	}