fs/xfs/xfs_utils.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_bit.h"
 #include "xfs_log.h"
 #include "xfs_inum.h"
 #include "xfs_trans.h"
 #include "xfs_sb.h"
 #include "xfs_ag.h"
 #include "xfs_dir2.h"
 #include "xfs_dmapi.h"
 #include "xfs_mount.h"
 #include "xfs_bmap_btree.h"
 #include "xfs_dir2_sf.h"
 #include "xfs_attr_sf.h"
 #include "xfs_dinode.h"
 #include "xfs_inode.h"
 #include "xfs_inode_item.h"
 #include "xfs_bmap.h"
 #include "xfs_error.h"
 #include "xfs_quota.h"
 #include "xfs_rw.h"
 #include "xfs_itable.h"
 #include "xfs_utils.h"


 /*
  * Allocates a new inode from disk and return a pointer to the
  * incore copy. This routine will internally commit the current
  * transaction and allocate a new one if the Space Manager needed
  * to do an allocation to replenish the inode free-list.
  *
  * This routine is designed to be called from xfs_create and
  * xfs_create_dir.
  *
  */
 int
 xfs_dir_ialloc(
 	xfs_trans_t	**tpp,		/* input: current transaction;
 					   output: may be a new transaction. */
 	xfs_inode_t	*dp,		/* directory within whose allocate
 					   the inode. */
 	mode_t		mode,
 	xfs_nlink_t	nlink,
 	xfs_dev_t	rdev,
 	cred_t		*credp,
 	prid_t		prid,		/* project id */
 	int		okalloc,	/* ok to allocate new space */
 	xfs_inode_t	**ipp,		/* pointer to inode; it will be
 					   locked. */
 	int		*committed)

 {
 	xfs_trans_t	*tp;
 	xfs_trans_t	*ntp;
 	xfs_inode_t	*ip;
 	xfs_buf_t	*ialloc_context = NULL;
 	boolean_t	call_again = B_FALSE;
 	int		code;
 	uint		log_res;
 	uint		log_count;
 	void		*dqinfo;
 	uint		tflags;

 	tp = *tpp;
 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);

 	/*
 	 * xfs_ialloc will return a pointer to an incore inode if
 	 * the Space Manager has an available inode on the free
 	 * list. Otherwise, it will do an allocation and replenish
 	 * the freelist.  Since we can only do one allocation per
 	 * transaction without deadlocks, we will need to commit the
 	 * current transaction and start a new one.  We will then
 	 * need to call xfs_ialloc again to get the inode.
 	 *
 	 * If xfs_ialloc did an allocation to replenish the freelist,
 	 * it returns the bp containing the head of the freelist as
 	 * ialloc_context. We will hold a lock on it across the
 	 * transaction commit so that no other process can steal
 	 * the inode(s) that we've just allocated.
 	 */
 	code = xfs_ialloc(tp, dp, mode, nlink, rdev, credp, prid, okalloc,
 			  &ialloc_context, &call_again, &ip);

 	/*
 	 * Return an error if we were unable to allocate a new inode.
 	 * This should only happen if we run out of space on disk or
 	 * encounter a disk error.
 	 */
 	if (code) {
 		*ipp = NULL;
 		return code;
 	}
 	if (!call_again && (ip == NULL)) {
 		*ipp = NULL;
 		return XFS_ERROR(ENOSPC);
 	}

 	/*
 	 * If call_again is set, then we were unable to get an
 	 * inode in one operation.  We need to commit the current
 	 * transaction and call xfs_ialloc() again.  It is guaranteed
 	 * to succeed the second time.
 	 */
 	if (call_again) {

 		/*
 		 * Normally, xfs_trans_commit releases all the locks.
 		 * We call bhold to hang on to the ialloc_context across
 		 * the commit.  Holding this buffer prevents any other
 		 * processes from doing any allocations in this
 		 * allocation group.
 		 */
 		xfs_trans_bhold(tp, ialloc_context);
 		/*
 		 * Save the log reservation so we can use
 		 * them in the next transaction.
 		 */
 		log_res = xfs_trans_get_log_res(tp);
 		log_count = xfs_trans_get_log_count(tp);

 		/*
 		 * We want the quota changes to be associated with the next
 		 * transaction, NOT this one. So, detach the dqinfo from this
 		 * and attach it to the next transaction.
 		 */
 		dqinfo = NULL;
 		tflags = 0;
 		if (tp->t_dqinfo) {
 			dqinfo = (void *)tp->t_dqinfo;
 			tp->t_dqinfo = NULL;
 			tflags = tp->t_flags & XFS_TRANS_DQ_DIRTY;
 			tp->t_flags &= ~(XFS_TRANS_DQ_DIRTY);
 		}

 		ntp = xfs_trans_dup(tp);
 		code = xfs_trans_commit(tp, 0);
 		tp = ntp;
 		if (committed != NULL) {
 			*committed = 1;
 		}
 		/*
 		 * If we get an error during the commit processing,
 		 * release the buffer that is still held and return
 		 * to the caller.
 		 */
 		if (code) {
 			xfs_buf_relse(ialloc_context);
 			if (dqinfo) {
 				tp->t_dqinfo = dqinfo;
 				XFS_TRANS_FREE_DQINFO(tp->t_mountp, tp);
 			}
 			*tpp = ntp;
 			*ipp = NULL;
 			return code;
 		}
 		code = xfs_trans_reserve(tp, 0, log_res, 0,
 					 XFS_TRANS_PERM_LOG_RES, log_count);
 		/*
 		 * Re-attach the quota info that we detached from prev trx.
 		 */
 		if (dqinfo) {
 			tp->t_dqinfo = dqinfo;
 			tp->t_flags |= tflags;
 		}

 		if (code) {
 			xfs_buf_relse(ialloc_context);
 			*tpp = ntp;
 			*ipp = NULL;
 			return code;
 		}
 		xfs_trans_bjoin(tp, ialloc_context);

 		/*
 		 * Call ialloc again. Since we've locked out all
 		 * other allocations in this allocation group,
 		 * this call should always succeed.
 		 */
 		code = xfs_ialloc(tp, dp, mode, nlink, rdev, credp, prid,
 				  okalloc, &ialloc_context, &call_again, &ip);

 		/*
 		 * If we get an error at this point, return to the caller
 		 * so that the current transaction can be aborted.
 		 */
 		if (code) {
 			*tpp = tp;
 			*ipp = NULL;
 			return code;
 		}
 		ASSERT ((!call_again) && (ip != NULL));

 	} else {
 		if (committed != NULL) {
 			*committed = 0;
 		}
 	}

 	*ipp = ip;
 	*tpp = tp;

 	return 0;
 }

 /*
  * Decrement the link count on an inode & log the change.
  * If this causes the link count to go to zero, initiate the
  * logging activity required to truncate a file.
  */
 int				/* error */
 xfs_droplink(
 	xfs_trans_t *tp,
 	xfs_inode_t *ip)
 {
 	int	error;

 	xfs_ichgtime(ip, XFS_ICHGTIME_CHG);

 	ASSERT (ip->i_d.di_nlink > 0);
 	ip->i_d.di_nlink--;
 	drop_nlink(ip->i_vnode);
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

 	error = 0;
 	if (ip->i_d.di_nlink == 0) {
 		/*
 		 * We're dropping the last link to this file.
 		 * Move the on-disk inode to the AGI unlinked list.
 		 * From xfs_inactive() we will pull the inode from
 		 * the list and free it.
 		 */
 		error = xfs_iunlink(tp, ip);
 	}
 	return error;
 }

 /*
  * This gets called when the inode's version needs to be changed from 1 to 2.
  * Currently this happens when the nlink field overflows the old 16-bit value
  * or when chproj is called to change the project for the first time.
  * As a side effect the superblock version will also get rev'd
  * to contain the NLINK bit.
  */
 void
 xfs_bump_ino_vers2(
 	xfs_trans_t	*tp,
 	xfs_inode_t	*ip)
 {
 	xfs_mount_t	*mp;

 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 	ASSERT(ip->i_d.di_version == XFS_DINODE_VERSION_1);

 	ip->i_d.di_version = XFS_DINODE_VERSION_2;
 	ip->i_d.di_onlink = 0;
 	memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
 	mp = tp->t_mountp;
 	if (!xfs_sb_version_hasnlink(&mp->m_sb)) {
 		spin_lock(&mp->m_sb_lock);
 		if (!xfs_sb_version_hasnlink(&mp->m_sb)) {
 			xfs_sb_version_addnlink(&mp->m_sb);
 			spin_unlock(&mp->m_sb_lock);
 			xfs_mod_sb(tp, XFS_SB_VERSIONNUM);
 		} else {
 			spin_unlock(&mp->m_sb_lock);
 		}
 	}
 	/* Caller must log the inode */
 }

 /*
  * Increment the link count on an inode & log the change.
  */
 int
 xfs_bumplink(
 	xfs_trans_t *tp,
 	xfs_inode_t *ip)
 {
 	if (ip->i_d.di_nlink >= XFS_MAXLINK)
 		return XFS_ERROR(EMLINK);
 	xfs_ichgtime(ip, XFS_ICHGTIME_CHG);

 	ASSERT(ip->i_d.di_nlink > 0);
 	ip->i_d.di_nlink++;
 	inc_nlink(ip->i_vnode);
 	if ((ip->i_d.di_version == XFS_DINODE_VERSION_1) &&
 	    (ip->i_d.di_nlink > XFS_MAXLINK_1)) {
 		/*
 		 * The inode has increased its number of links beyond
 		 * what can fit in an old format inode.  It now needs
 		 * to be converted to a version 2 inode with a 32 bit
 		 * link count.  If this is the first inode in the file
 		 * system to do this, then we need to bump the superblock
 		 * version number as well.
 		 */
 		xfs_bump_ino_vers2(tp, ip);
 	}

 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 	return 0;
 }

 /*
  * Try to truncate the given file to 0 length.  Currently called
  * only out of xfs_remove when it has to truncate a file to free
  * up space for the remove to proceed.
  */
 int
 xfs_truncate_file(
 	xfs_mount_t	*mp,
 	xfs_inode_t	*ip)
 {
 	xfs_trans_t	*tp;
 	int		error;

 #ifdef QUOTADEBUG
 	/*
 	 * This is called to truncate the quotainodes too.
 	 */
 	if (XFS_IS_UQUOTA_ON(mp)) {
 		if (ip->i_ino != mp->m_sb.sb_uquotino)
 			ASSERT(ip->i_udquot);
 	}
 	if (XFS_IS_OQUOTA_ON(mp)) {
 		if (ip->i_ino != mp->m_sb.sb_gquotino)
 			ASSERT(ip->i_gdquot);
 	}
 #endif
 	/*
 	 * Make the call to xfs_itruncate_start before starting the
 	 * transaction, because we cannot make the call while we're
 	 * in a transaction.
 	 */
 	xfs_ilock(ip, XFS_IOLOCK_EXCL);
 	error = xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE, (xfs_fsize_t)0);
 	if (error) {
 		xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 		return error;
 	}

 	tp = xfs_trans_alloc(mp, XFS_TRANS_TRUNCATE_FILE);
 	if ((error = xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0,
 				      XFS_TRANS_PERM_LOG_RES,
 				      XFS_ITRUNCATE_LOG_COUNT))) {
 		xfs_trans_cancel(tp, 0);
 		xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 		return error;
 	}

 	/*
 	 * Follow the normal truncate locking protocol.  Since we
 	 * hold the inode in the transaction, we know that it's number
 	 * of references will stay constant.
 	 */
 	xfs_ilock(ip, XFS_ILOCK_EXCL);
 	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
 	xfs_trans_ihold(tp, ip);
 	/*
 	 * Signal a sync xaction.  The only case where that isn't
 	 * the case is if we're truncating an already unlinked file
 	 * on a wsync fs.  In that case, we know the blocks can't
 	 * reappear in the file because the links to file are
 	 * permanently toast.  Currently, we're always going to
 	 * want a sync transaction because this code is being
 	 * called from places where nlink is guaranteed to be 1
 	 * but I'm leaving the tests in to protect against future
 	 * changes -- rcc.
 	 */
 	error = xfs_itruncate_finish(&tp, ip, (xfs_fsize_t)0,
 				     XFS_DATA_FORK,
 				     ((ip->i_d.di_nlink != 0 ||
 				       !(mp->m_flags & XFS_MOUNT_WSYNC))
 				      ? 1 : 0));
 	if (error) {
 		xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES |
 				 XFS_TRANS_ABORT);
 	} else {
 		xfs_ichgtime(ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 		error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
 	}
 	xfs_iunlock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);

 	return error;
 }
	/*
	* 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_bit.h"
	#include "xfs_log.h"
	#include "xfs_inum.h"
	#include "xfs_trans.h"
	#include "xfs_sb.h"
	#include "xfs_ag.h"
	#include "xfs_dir2.h"
	#include "xfs_dmapi.h"
	#include "xfs_mount.h"
	#include "xfs_bmap_btree.h"
	#include "xfs_dir2_sf.h"
	#include "xfs_attr_sf.h"
	#include "xfs_dinode.h"
	#include "xfs_inode.h"
	#include "xfs_inode_item.h"
	#include "xfs_bmap.h"
	#include "xfs_error.h"
	#include "xfs_quota.h"
	#include "xfs_rw.h"
	#include "xfs_itable.h"
	#include "xfs_utils.h"


	/*
	* Allocates a new inode from disk and return a pointer to the
	* incore copy. This routine will internally commit the current
	* transaction and allocate a new one if the Space Manager needed
	* to do an allocation to replenish the inode free-list.
	*
	* This routine is designed to be called from xfs_create and
	* xfs_create_dir.
	*
	*/
	int
	xfs_dir_ialloc(
	xfs_trans_t *tpp, / input: current transaction;
	output: may be a new transaction. */
	xfs_inode_t dp, / directory within whose allocate
	the inode. */
	mode_t mode,
	xfs_nlink_t nlink,
	xfs_dev_t rdev,
	cred_t *credp,
	prid_t prid, /* project id */
	int okalloc, /* ok to allocate new space */
	xfs_inode_t *ipp, / pointer to inode; it will be
	locked. */
	int *committed)

	{
	xfs_trans_t *tp;
	xfs_trans_t *ntp;
	xfs_inode_t *ip;
	xfs_buf_t *ialloc_context = NULL;
	boolean_t call_again = B_FALSE;
	int code;
	uint log_res;
	uint log_count;
	void *dqinfo;
	uint tflags;

	tp = *tpp;
	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);

	/*
	* xfs_ialloc will return a pointer to an incore inode if
	* the Space Manager has an available inode on the free
	* list. Otherwise, it will do an allocation and replenish
	* the freelist. Since we can only do one allocation per
	* transaction without deadlocks, we will need to commit the
	* current transaction and start a new one. We will then
	* need to call xfs_ialloc again to get the inode.
	*
	* If xfs_ialloc did an allocation to replenish the freelist,
	* it returns the bp containing the head of the freelist as
	* ialloc_context. We will hold a lock on it across the
	* transaction commit so that no other process can steal
	* the inode(s) that we've just allocated.
	*/
	code = xfs_ialloc(tp, dp, mode, nlink, rdev, credp, prid, okalloc,
	&ialloc_context, &call_again, &ip);

	/*
	* Return an error if we were unable to allocate a new inode.
	* This should only happen if we run out of space on disk or
	* encounter a disk error.
	*/
	if (code) {
	*ipp = NULL;
	return code;
	}
	if (!call_again && (ip == NULL)) {
	*ipp = NULL;
	return XFS_ERROR(ENOSPC);
	}

	/*
	* If call_again is set, then we were unable to get an
	* inode in one operation. We need to commit the current
	* transaction and call xfs_ialloc() again. It is guaranteed
	* to succeed the second time.
	*/
	if (call_again) {

	/*
	* Normally, xfs_trans_commit releases all the locks.
	* We call bhold to hang on to the ialloc_context across
	* the commit. Holding this buffer prevents any other
	* processes from doing any allocations in this
	* allocation group.
	*/
	xfs_trans_bhold(tp, ialloc_context);
	/*
	* Save the log reservation so we can use
	* them in the next transaction.
	*/
	log_res = xfs_trans_get_log_res(tp);
	log_count = xfs_trans_get_log_count(tp);

	/*
	* We want the quota changes to be associated with the next
	* transaction, NOT this one. So, detach the dqinfo from this
	* and attach it to the next transaction.
	*/
	dqinfo = NULL;
	tflags = 0;
	if (tp->t_dqinfo) {
	dqinfo = (void *)tp->t_dqinfo;
	tp->t_dqinfo = NULL;
	tflags = tp->t_flags & XFS_TRANS_DQ_DIRTY;
	tp->t_flags &= ~(XFS_TRANS_DQ_DIRTY);
	}

	ntp = xfs_trans_dup(tp);
	code = xfs_trans_commit(tp, 0);
	tp = ntp;
	if (committed != NULL) {
	*committed = 1;
	}
	/*
	* If we get an error during the commit processing,
	* release the buffer that is still held and return
	* to the caller.
	*/
	if (code) {
	xfs_buf_relse(ialloc_context);
	if (dqinfo) {
	tp->t_dqinfo = dqinfo;
	XFS_TRANS_FREE_DQINFO(tp->t_mountp, tp);
	}
	*tpp = ntp;
	*ipp = NULL;
	return code;
	}
	code = xfs_trans_reserve(tp, 0, log_res, 0,
	XFS_TRANS_PERM_LOG_RES, log_count);
	/*
	* Re-attach the quota info that we detached from prev trx.
	*/
	if (dqinfo) {
	tp->t_dqinfo = dqinfo;
	tp->t_flags \|= tflags;
	}

	if (code) {
	xfs_buf_relse(ialloc_context);
	*tpp = ntp;
	*ipp = NULL;
	return code;
	}
	xfs_trans_bjoin(tp, ialloc_context);

	/*
	* Call ialloc again. Since we've locked out all
	* other allocations in this allocation group,
	* this call should always succeed.
	*/
	code = xfs_ialloc(tp, dp, mode, nlink, rdev, credp, prid,
	okalloc, &ialloc_context, &call_again, &ip);

	/*
	* If we get an error at this point, return to the caller
	* so that the current transaction can be aborted.
	*/
	if (code) {
	*tpp = tp;
	*ipp = NULL;
	return code;
	}
	ASSERT ((!call_again) && (ip != NULL));

	} else {
	if (committed != NULL) {
	*committed = 0;
	}
	}

	*ipp = ip;
	*tpp = tp;

	return 0;
	}

	/*
	* Decrement the link count on an inode & log the change.
	* If this causes the link count to go to zero, initiate the
	* logging activity required to truncate a file.
	*/
	int /* error */
	xfs_droplink(
	xfs_trans_t *tp,
	xfs_inode_t *ip)
	{
	int error;

	xfs_ichgtime(ip, XFS_ICHGTIME_CHG);

	ASSERT (ip->i_d.di_nlink > 0);
	ip->i_d.di_nlink--;
	drop_nlink(ip->i_vnode);
	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

	error = 0;
	if (ip->i_d.di_nlink == 0) {
	/*
	* We're dropping the last link to this file.
	* Move the on-disk inode to the AGI unlinked list.
	* From xfs_inactive() we will pull the inode from
	* the list and free it.
	*/
	error = xfs_iunlink(tp, ip);
	}
	return error;
	}

	/*
	* This gets called when the inode's version needs to be changed from 1 to 2.
	* Currently this happens when the nlink field overflows the old 16-bit value
	* or when chproj is called to change the project for the first time.
	* As a side effect the superblock version will also get rev'd
	* to contain the NLINK bit.
	*/
	void
	xfs_bump_ino_vers2(
	xfs_trans_t *tp,
	xfs_inode_t *ip)
	{
	xfs_mount_t *mp;

	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
	ASSERT(ip->i_d.di_version == XFS_DINODE_VERSION_1);

	ip->i_d.di_version = XFS_DINODE_VERSION_2;
	ip->i_d.di_onlink = 0;
	memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
	mp = tp->t_mountp;
	if (!xfs_sb_version_hasnlink(&mp->m_sb)) {
	spin_lock(&mp->m_sb_lock);
	if (!xfs_sb_version_hasnlink(&mp->m_sb)) {
	xfs_sb_version_addnlink(&mp->m_sb);
	spin_unlock(&mp->m_sb_lock);
	xfs_mod_sb(tp, XFS_SB_VERSIONNUM);
	} else {
	spin_unlock(&mp->m_sb_lock);
	}
	}
	/* Caller must log the inode */
	}

	/*
	* Increment the link count on an inode & log the change.
	*/
	int
	xfs_bumplink(
	xfs_trans_t *tp,
	xfs_inode_t *ip)
	{
	if (ip->i_d.di_nlink >= XFS_MAXLINK)
	return XFS_ERROR(EMLINK);
	xfs_ichgtime(ip, XFS_ICHGTIME_CHG);

	ASSERT(ip->i_d.di_nlink > 0);
	ip->i_d.di_nlink++;
	inc_nlink(ip->i_vnode);
	if ((ip->i_d.di_version == XFS_DINODE_VERSION_1) &&
	(ip->i_d.di_nlink > XFS_MAXLINK_1)) {
	/*
	* The inode has increased its number of links beyond
	* what can fit in an old format inode. It now needs
	* to be converted to a version 2 inode with a 32 bit
	* link count. If this is the first inode in the file
	* system to do this, then we need to bump the superblock
	* version number as well.
	*/
	xfs_bump_ino_vers2(tp, ip);
	}

	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
	return 0;
	}

	/*
	* Try to truncate the given file to 0 length. Currently called
	* only out of xfs_remove when it has to truncate a file to free
	* up space for the remove to proceed.
	*/
	int
	xfs_truncate_file(
	xfs_mount_t *mp,
	xfs_inode_t *ip)
	{
	xfs_trans_t *tp;
	int error;

	#ifdef QUOTADEBUG
	/*
	* This is called to truncate the quotainodes too.
	*/
	if (XFS_IS_UQUOTA_ON(mp)) {
	if (ip->i_ino != mp->m_sb.sb_uquotino)
	ASSERT(ip->i_udquot);
	}
	if (XFS_IS_OQUOTA_ON(mp)) {
	if (ip->i_ino != mp->m_sb.sb_gquotino)
	ASSERT(ip->i_gdquot);
	}
	#endif
	/*
	* Make the call to xfs_itruncate_start before starting the
	* transaction, because we cannot make the call while we're
	* in a transaction.
	*/
	xfs_ilock(ip, XFS_IOLOCK_EXCL);
	error = xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE, (xfs_fsize_t)0);
	if (error) {
	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
	return error;
	}

	tp = xfs_trans_alloc(mp, XFS_TRANS_TRUNCATE_FILE);
	if ((error = xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0,
	XFS_TRANS_PERM_LOG_RES,
	XFS_ITRUNCATE_LOG_COUNT))) {
	xfs_trans_cancel(tp, 0);
	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
	return error;
	}

	/*
	* Follow the normal truncate locking protocol. Since we
	* hold the inode in the transaction, we know that it's number
	* of references will stay constant.
	*/
	xfs_ilock(ip, XFS_ILOCK_EXCL);
	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL \| XFS_IOLOCK_EXCL);
	xfs_trans_ihold(tp, ip);
	/*
	* Signal a sync xaction. The only case where that isn't
	* the case is if we're truncating an already unlinked file
	* on a wsync fs. In that case, we know the blocks can't
	* reappear in the file because the links to file are
	* permanently toast. Currently, we're always going to
	* want a sync transaction because this code is being
	* called from places where nlink is guaranteed to be 1
	* but I'm leaving the tests in to protect against future
	* changes -- rcc.
	*/
	error = xfs_itruncate_finish(&tp, ip, (xfs_fsize_t)0,
	XFS_DATA_FORK,
	((ip->i_d.di_nlink != 0 \|\|
	!(mp->m_flags & XFS_MOUNT_WSYNC))
	? 1 : 0));
	if (error) {
	xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES \|
	XFS_TRANS_ABORT);
	} else {
	xfs_ichgtime(ip, XFS_ICHGTIME_MOD \| XFS_ICHGTIME_CHG);
	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
	}
	xfs_iunlock(ip, XFS_ILOCK_EXCL \| XFS_IOLOCK_EXCL);

	return error;
	}