/*
   * Copyright (c) 2000-2006 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 <linux/log2.h>
  
  #include "xfs.h"
  #include "xfs_fs.h"
  #include "xfs_shared.h"
  #include "xfs_format.h"
  #include "xfs_log_format.h"
  #include "xfs_trans_resv.h"
  #include "xfs_inum.h"
  #include "xfs_sb.h"
  #include "xfs_ag.h"
  #include "xfs_mount.h"
  #include "xfs_inode.h"
  #include "xfs_da_format.h"
  #include "xfs_da_btree.h"
  #include "xfs_dir2.h"
  #include "xfs_attr_sf.h"
  #include "xfs_attr.h"
  #include "xfs_trans_space.h"
  #include "xfs_trans.h"
  #include "xfs_buf_item.h"
  #include "xfs_inode_item.h"
  #include "xfs_ialloc.h"
  #include "xfs_bmap.h"
  #include "xfs_bmap_util.h"
  #include "xfs_error.h"
  #include "xfs_quota.h"
  #include "xfs_dinode.h"
  #include "xfs_filestream.h"
  #include "xfs_cksum.h"
  #include "xfs_trace.h"
  #include "xfs_icache.h"
  #include "xfs_symlink.h"
  #include "xfs_trans_priv.h"
  #include "xfs_log.h"
  #include "xfs_bmap_btree.h"
  
  kmem_zone_t *xfs_inode_zone;
  
  /*
   * Used in xfs_itruncate_extents().  This is the maximum number of extents
   * freed from a file in a single transaction.
   */
  #define	XFS_ITRUNC_MAX_EXTENTS	2
  
  STATIC int xfs_iflush_int(xfs_inode_t *, xfs_buf_t *);
  
  /*
   * helper function to extract extent size hint from inode
   */
  xfs_extlen_t
  xfs_get_extsz_hint(
  	struct xfs_inode	*ip)
  {
  	if ((ip->i_d.di_flags & XFS_DIFLAG_EXTSIZE) && ip->i_d.di_extsize)
  		return ip->i_d.di_extsize;
  	if (XFS_IS_REALTIME_INODE(ip))
  		return ip->i_mount->m_sb.sb_rextsize;
  	return 0;
  }
  
  /*
   * These two are wrapper routines around the xfs_ilock() routine used to
   * centralize some grungy code.  They are used in places that wish to lock the
   * inode solely for reading the extents.  The reason these places can't just
   * call xfs_ilock(ip, XFS_ILOCK_SHARED) is that the inode lock also guards to
   * bringing in of the extents from disk for a file in b-tree format.  If the
   * inode is in b-tree format, then we need to lock the inode exclusively until
   * the extents are read in.  Locking it exclusively all the time would limit
   * our parallelism unnecessarily, though.  What we do instead is check to see
   * if the extents have been read in yet, and only lock the inode exclusively
   * if they have not.
   *
   * The functions return a value which should be given to the corresponding
   * xfs_iunlock() call.
   */
  uint
  xfs_ilock_data_map_shared(
  	struct xfs_inode	*ip)
  {
  	uint			lock_mode = XFS_ILOCK_SHARED;
  
  	if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE &&
  	    (ip->i_df.if_flags & XFS_IFEXTENTS) == 0)
  		lock_mode = XFS_ILOCK_EXCL;
  	xfs_ilock(ip, lock_mode);
  	return lock_mode;
  }
  
  uint
  xfs_ilock_attr_map_shared(
  	struct xfs_inode	*ip)
  {
  	uint			lock_mode = XFS_ILOCK_SHARED;
  
  	if (ip->i_d.di_aformat == XFS_DINODE_FMT_BTREE &&
  	    (ip->i_afp->if_flags & XFS_IFEXTENTS) == 0)
  		lock_mode = XFS_ILOCK_EXCL;
  	xfs_ilock(ip, lock_mode);
  	return lock_mode;
  }
  
  /*
   * The xfs inode contains 2 locks: a multi-reader lock called the
   * i_iolock and a multi-reader lock called the i_lock.  This routine
   * allows either or both of the locks to be obtained.
   *
   * The 2 locks should always be ordered so that the IO lock is
   * obtained first in order to prevent deadlock.
   *
   * ip -- the inode being locked
   * lock_flags -- this parameter indicates the inode's locks
   *       to be locked.  It can be:
   *		XFS_IOLOCK_SHARED,
   *		XFS_IOLOCK_EXCL,
   *		XFS_ILOCK_SHARED,
   *		XFS_ILOCK_EXCL,
   *		XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED,
   *		XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL,
   *		XFS_IOLOCK_EXCL | XFS_ILOCK_SHARED,
   *		XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL
   */
  void
  xfs_ilock(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	trace_xfs_ilock(ip, lock_flags, _RET_IP_);
  
  	/*
  	 * You can't set both SHARED and EXCL for the same lock,
  	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
  	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
  	 */
  	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
  	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
  	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
  	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
  
  	if (lock_flags & XFS_IOLOCK_EXCL)
  		mrupdate_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
  	else if (lock_flags & XFS_IOLOCK_SHARED)
  		mraccess_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
  
  	if (lock_flags & XFS_ILOCK_EXCL)
  		mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
  	else if (lock_flags & XFS_ILOCK_SHARED)
  		mraccess_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
  }
  
  /*
   * This is just like xfs_ilock(), except that the caller
   * is guaranteed not to sleep.  It returns 1 if it gets
   * the requested locks and 0 otherwise.  If the IO lock is
   * obtained but the inode lock cannot be, then the IO lock
   * is dropped before returning.
   *
   * ip -- the inode being locked
   * lock_flags -- this parameter indicates the inode's locks to be
   *       to be locked.  See the comment for xfs_ilock() for a list
   *	 of valid values.
   */
  int
  xfs_ilock_nowait(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	trace_xfs_ilock_nowait(ip, lock_flags, _RET_IP_);
  
  	/*
  	 * You can't set both SHARED and EXCL for the same lock,
  	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
  	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
  	 */
  	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
  	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
  	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
  	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
  
  	if (lock_flags & XFS_IOLOCK_EXCL) {
  		if (!mrtryupdate(&ip->i_iolock))
  			goto out;
  	} else if (lock_flags & XFS_IOLOCK_SHARED) {
  		if (!mrtryaccess(&ip->i_iolock))
  			goto out;
  	}
  	if (lock_flags & XFS_ILOCK_EXCL) {
  		if (!mrtryupdate(&ip->i_lock))
  			goto out_undo_iolock;
  	} else if (lock_flags & XFS_ILOCK_SHARED) {
  		if (!mrtryaccess(&ip->i_lock))
  			goto out_undo_iolock;
  	}
  	return 1;
  
   out_undo_iolock:
  	if (lock_flags & XFS_IOLOCK_EXCL)
  		mrunlock_excl(&ip->i_iolock);
  	else if (lock_flags & XFS_IOLOCK_SHARED)
  		mrunlock_shared(&ip->i_iolock);
   out:
  	return 0;
  }
  
  /*
   * xfs_iunlock() is used to drop the inode locks acquired with
   * xfs_ilock() and xfs_ilock_nowait().  The caller must pass
   * in the flags given to xfs_ilock() or xfs_ilock_nowait() so
   * that we know which locks to drop.
   *
   * ip -- the inode being unlocked
   * lock_flags -- this parameter indicates the inode's locks to be
   *       to be unlocked.  See the comment for xfs_ilock() for a list
   *	 of valid values for this parameter.
   *
   */
  void
  xfs_iunlock(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	/*
  	 * You can't set both SHARED and EXCL for the same lock,
  	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
  	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
  	 */
  	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
  	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
  	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
  	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
  	ASSERT(lock_flags != 0);
  
  	if (lock_flags & XFS_IOLOCK_EXCL)
  		mrunlock_excl(&ip->i_iolock);
  	else if (lock_flags & XFS_IOLOCK_SHARED)
  		mrunlock_shared(&ip->i_iolock);
  
  	if (lock_flags & XFS_ILOCK_EXCL)
  		mrunlock_excl(&ip->i_lock);
  	else if (lock_flags & XFS_ILOCK_SHARED)
  		mrunlock_shared(&ip->i_lock);
  
  	trace_xfs_iunlock(ip, lock_flags, _RET_IP_);
  }
  
  /*
   * give up write locks.  the i/o lock cannot be held nested
   * if it is being demoted.
   */
  void
  xfs_ilock_demote(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL));
  	ASSERT((lock_flags & ~(XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
  
  	if (lock_flags & XFS_ILOCK_EXCL)
  		mrdemote(&ip->i_lock);
  	if (lock_flags & XFS_IOLOCK_EXCL)
  		mrdemote(&ip->i_iolock);
  
  	trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
  }
  
  #if defined(DEBUG) || defined(XFS_WARN)
  int
  xfs_isilocked(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
  		if (!(lock_flags & XFS_ILOCK_SHARED))
  			return !!ip->i_lock.mr_writer;
  		return rwsem_is_locked(&ip->i_lock.mr_lock);
  	}
  
  	if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
  		if (!(lock_flags & XFS_IOLOCK_SHARED))
  			return !!ip->i_iolock.mr_writer;
  		return rwsem_is_locked(&ip->i_iolock.mr_lock);
  	}
  
  	ASSERT(0);
  	return 0;
  }
  #endif
  
  #ifdef DEBUG
  int xfs_locked_n;
  int xfs_small_retries;
  int xfs_middle_retries;
  int xfs_lots_retries;
  int xfs_lock_delays;
  #endif
  
  /*
   * Bump the subclass so xfs_lock_inodes() acquires each lock with
   * a different value
   */
  static inline int
  xfs_lock_inumorder(int lock_mode, int subclass)
  {
  	if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL))
  		lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_IOLOCK_SHIFT;
  	if (lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL))
  		lock_mode |= (subclass + XFS_LOCK_INUMORDER) << XFS_ILOCK_SHIFT;
  
  	return lock_mode;
  }
  
  /*
   * The following routine will lock n inodes in exclusive mode.
   * We assume the caller calls us with the inodes in i_ino order.
   *
   * We need to detect deadlock where an inode that we lock
   * is in the AIL and we start waiting for another inode that is locked
   * by a thread in a long running transaction (such as truncate). This can
   * result in deadlock since the long running trans might need to wait
   * for the inode we just locked in order to push the tail and free space
   * in the log.
   */
  void
  xfs_lock_inodes(
  	xfs_inode_t	**ips,
  	int		inodes,
  	uint		lock_mode)
  {
  	int		attempts = 0, i, j, try_lock;
  	xfs_log_item_t	*lp;
  
  	ASSERT(ips && (inodes >= 2)); /* we need at least two */
  
  	try_lock = 0;
  	i = 0;
  
  again:
  	for (; i < inodes; i++) {
  		ASSERT(ips[i]);
  
  		if (i && (ips[i] == ips[i-1]))	/* Already locked */
  			continue;
  
  		/*
  		 * If try_lock is not set yet, make sure all locked inodes
  		 * are not in the AIL.
  		 * If any are, set try_lock to be used later.
  		 */
  
  		if (!try_lock) {
  			for (j = (i - 1); j >= 0 && !try_lock; j--) {
  				lp = (xfs_log_item_t *)ips[j]->i_itemp;
  				if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
  					try_lock++;
  				}
  			}
  		}
  
  		/*
  		 * If any of the previous locks we have locked is in the AIL,
  		 * we must TRY to get the second and subsequent locks. If
  		 * we can't get any, we must release all we have
  		 * and try again.
  		 */
  
  		if (try_lock) {
  			/* try_lock must be 0 if i is 0. */
  			/*
  			 * try_lock means we have an inode locked
  			 * that is in the AIL.
  			 */
  			ASSERT(i != 0);
  			if (!xfs_ilock_nowait(ips[i], xfs_lock_inumorder(lock_mode, i))) {
  				attempts++;
  
  				/*
  				 * Unlock all previous guys and try again.
  				 * xfs_iunlock will try to push the tail
  				 * if the inode is in the AIL.
  				 */
  
  				for(j = i - 1; j >= 0; j--) {
  
  					/*
  					 * Check to see if we've already
  					 * unlocked this one.
  					 * Not the first one going back,
  					 * and the inode ptr is the same.
  					 */
  					if ((j != (i - 1)) && ips[j] ==
  								ips[j+1])
  						continue;
  
  					xfs_iunlock(ips[j], lock_mode);
  				}
  
  				if ((attempts % 5) == 0) {
  					delay(1); /* Don't just spin the CPU */
  #ifdef DEBUG
  					xfs_lock_delays++;
  #endif
  				}
  				i = 0;
  				try_lock = 0;
  				goto again;
  			}
  		} else {
  			xfs_ilock(ips[i], xfs_lock_inumorder(lock_mode, i));
  		}
  	}
  
  #ifdef DEBUG
  	if (attempts) {
  		if (attempts < 5) xfs_small_retries++;
  		else if (attempts < 100) xfs_middle_retries++;
  		else xfs_lots_retries++;
  	} else {
  		xfs_locked_n++;
  	}
  #endif
  }
  
  /*
   * xfs_lock_two_inodes() can only be used to lock one type of lock
   * at a time - the iolock or the ilock, but not both at once. If
   * we lock both at once, lockdep will report false positives saying
   * we have violated locking orders.
   */
  void
  xfs_lock_two_inodes(
  	xfs_inode_t		*ip0,
  	xfs_inode_t		*ip1,
  	uint			lock_mode)
  {
  	xfs_inode_t		*temp;
  	int			attempts = 0;
  	xfs_log_item_t		*lp;
  
  	if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL))
  		ASSERT((lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)) == 0);
  	ASSERT(ip0->i_ino != ip1->i_ino);
  
  	if (ip0->i_ino > ip1->i_ino) {
  		temp = ip0;
  		ip0 = ip1;
  		ip1 = temp;
  	}
  
   again:
  	xfs_ilock(ip0, xfs_lock_inumorder(lock_mode, 0));
  
  	/*
  	 * If the first lock we have locked is in the AIL, we must TRY to get
  	 * the second lock. If we can't get it, we must release the first one
  	 * and try again.
  	 */
  	lp = (xfs_log_item_t *)ip0->i_itemp;
  	if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
  		if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(lock_mode, 1))) {
  			xfs_iunlock(ip0, lock_mode);
  			if ((++attempts % 5) == 0)
  				delay(1); /* Don't just spin the CPU */
  			goto again;
  		}
  	} else {
  		xfs_ilock(ip1, xfs_lock_inumorder(lock_mode, 1));
  	}
  }
  
  
  void
  __xfs_iflock(
  	struct xfs_inode	*ip)
  {
  	wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IFLOCK_BIT);
  	DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IFLOCK_BIT);
  
  	do {
  		prepare_to_wait_exclusive(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
  		if (xfs_isiflocked(ip))
  			io_schedule();
  	} while (!xfs_iflock_nowait(ip));
  
  	finish_wait(wq, &wait.wait);
  }
  
  STATIC uint
  _xfs_dic2xflags(
  	__uint16_t		di_flags)
  {
  	uint			flags = 0;
  
  	if (di_flags & XFS_DIFLAG_ANY) {
  		if (di_flags & XFS_DIFLAG_REALTIME)
  			flags |= XFS_XFLAG_REALTIME;
  		if (di_flags & XFS_DIFLAG_PREALLOC)
  			flags |= XFS_XFLAG_PREALLOC;
  		if (di_flags & XFS_DIFLAG_IMMUTABLE)
  			flags |= XFS_XFLAG_IMMUTABLE;
  		if (di_flags & XFS_DIFLAG_APPEND)
  			flags |= XFS_XFLAG_APPEND;
  		if (di_flags & XFS_DIFLAG_SYNC)
  			flags |= XFS_XFLAG_SYNC;
  		if (di_flags & XFS_DIFLAG_NOATIME)
  			flags |= XFS_XFLAG_NOATIME;
  		if (di_flags & XFS_DIFLAG_NODUMP)
  			flags |= XFS_XFLAG_NODUMP;
  		if (di_flags & XFS_DIFLAG_RTINHERIT)
  			flags |= XFS_XFLAG_RTINHERIT;
  		if (di_flags & XFS_DIFLAG_PROJINHERIT)
  			flags |= XFS_XFLAG_PROJINHERIT;
  		if (di_flags & XFS_DIFLAG_NOSYMLINKS)
  			flags |= XFS_XFLAG_NOSYMLINKS;
  		if (di_flags & XFS_DIFLAG_EXTSIZE)
  			flags |= XFS_XFLAG_EXTSIZE;
  		if (di_flags & XFS_DIFLAG_EXTSZINHERIT)
  			flags |= XFS_XFLAG_EXTSZINHERIT;
  		if (di_flags & XFS_DIFLAG_NODEFRAG)
  			flags |= XFS_XFLAG_NODEFRAG;
  		if (di_flags & XFS_DIFLAG_FILESTREAM)
  			flags |= XFS_XFLAG_FILESTREAM;
  	}
  
  	return flags;
  }
  
  uint
  xfs_ip2xflags(
  	xfs_inode_t		*ip)
  {
  	xfs_icdinode_t		*dic = &ip->i_d;
  
  	return _xfs_dic2xflags(dic->di_flags) |
  				(XFS_IFORK_Q(ip) ? XFS_XFLAG_HASATTR : 0);
  }
  
  uint
  xfs_dic2xflags(
  	xfs_dinode_t		*dip)
  {
  	return _xfs_dic2xflags(be16_to_cpu(dip->di_flags)) |
  				(XFS_DFORK_Q(dip) ? XFS_XFLAG_HASATTR : 0);
  }
  
  /*
   * Lookups up an inode from "name". If ci_name is not NULL, then a CI match
   * is allowed, otherwise it has to be an exact match. If a CI match is found,
   * ci_name->name will point to a the actual name (caller must free) or
   * will be set to NULL if an exact match is found.
   */
  int
  xfs_lookup(
  	xfs_inode_t		*dp,
  	struct xfs_name		*name,
  	xfs_inode_t		**ipp,
  	struct xfs_name		*ci_name)
  {
  	xfs_ino_t		inum;
  	int			error;
  	uint			lock_mode;
  
  	trace_xfs_lookup(dp, name);
  
  	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
  		return XFS_ERROR(EIO);
  
  	lock_mode = xfs_ilock_data_map_shared(dp);
  	error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
  	xfs_iunlock(dp, lock_mode);
  
  	if (error)
  		goto out;
  
  	error = xfs_iget(dp->i_mount, NULL, inum, 0, 0, ipp);
  	if (error)
  		goto out_free_name;
  
  	return 0;
  
  out_free_name:
  	if (ci_name)
  		kmem_free(ci_name->name);
  out:
  	*ipp = NULL;
  	return error;
  }
  
  /*
   * Allocate an inode on disk and return a copy of its in-core version.
   * The in-core inode is locked exclusively.  Set mode, nlink, and rdev
   * appropriately within the inode.  The uid and gid for the inode are
   * set according to the contents of the given cred structure.
   *
   * Use xfs_dialloc() to allocate the on-disk inode. If xfs_dialloc()
   * has a free inode available, call xfs_iget() to obtain the in-core
   * version of the allocated inode.  Finally, fill in the inode and
   * log its initial contents.  In this case, ialloc_context would be
   * set to NULL.
   *
   * If xfs_dialloc() does not have an available inode, it will replenish
   * its supply by doing an allocation. Since we can only do one
   * allocation within a transaction without deadlocks, we must commit
   * the current transaction before returning the inode itself.
   * In this case, therefore, we will set ialloc_context and return.
   * The caller should then commit the current transaction, start a new
   * transaction, and call xfs_ialloc() again to actually get the inode.
   *
   * To ensure that some other process does not grab the inode that
   * was allocated during the first call to xfs_ialloc(), this routine
   * also returns the [locked] bp pointing to the head of the freelist
   * as ialloc_context.  The caller should hold this buffer across
   * the commit and pass it back into this routine on the second call.
   *
   * If we are allocating quota inodes, we do not have a parent inode
   * to attach to or associate with (i.e. pip == NULL) because they
   * are not linked into the directory structure - they are attached
   * directly to the superblock - and so have no parent.
   */
  int
  xfs_ialloc(
  	xfs_trans_t	*tp,
  	xfs_inode_t	*pip,
  	umode_t		mode,
  	xfs_nlink_t	nlink,
  	xfs_dev_t	rdev,
  	prid_t		prid,
  	int		okalloc,
  	xfs_buf_t	**ialloc_context,
  	xfs_inode_t	**ipp)
  {
  	struct xfs_mount *mp = tp->t_mountp;
  	xfs_ino_t	ino;
  	xfs_inode_t	*ip;
  	uint		flags;
  	int		error;
  	timespec_t	tv;
  	int		filestreams = 0;
  
  	/*
  	 * Call the space management code to pick
  	 * the on-disk inode to be allocated.
  	 */
  	error = xfs_dialloc(tp, pip ? pip->i_ino : 0, mode, okalloc,
  			    ialloc_context, &ino);
  	if (error)
  		return error;
  	if (*ialloc_context || ino == NULLFSINO) {
  		*ipp = NULL;
  		return 0;
  	}
  	ASSERT(*ialloc_context == NULL);
  
  	/*
  	 * Get the in-core inode with the lock held exclusively.
  	 * This is because we're setting fields here we need
  	 * to prevent others from looking at until we're done.
  	 */
  	error = xfs_iget(mp, tp, ino, XFS_IGET_CREATE,
  			 XFS_ILOCK_EXCL, &ip);
  	if (error)
  		return error;
  	ASSERT(ip != NULL);
  
  	ip->i_d.di_mode = mode;
  	ip->i_d.di_onlink = 0;
  	ip->i_d.di_nlink = nlink;
  	ASSERT(ip->i_d.di_nlink == nlink);
  	ip->i_d.di_uid = xfs_kuid_to_uid(current_fsuid());
  	ip->i_d.di_gid = xfs_kgid_to_gid(current_fsgid());
  	xfs_set_projid(ip, prid);
  	memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
  
  	/*
  	 * If the superblock version is up to where we support new format
  	 * inodes and this is currently an old format inode, then change
  	 * the inode version number now.  This way we only do the conversion
  	 * here rather than here and in the flush/logging code.
  	 */
  	if (xfs_sb_version_hasnlink(&mp->m_sb) &&
  	    ip->i_d.di_version == 1) {
  		ip->i_d.di_version = 2;
  		/*
  		 * We've already zeroed the old link count, the projid field,
  		 * and the pad field.
  		 */
  	}
  
  	/*
  	 * Project ids won't be stored on disk if we are using a version 1 inode.
  	 */
  	if ((prid != 0) && (ip->i_d.di_version == 1))
  		xfs_bump_ino_vers2(tp, ip);
  
  	if (pip && XFS_INHERIT_GID(pip)) {
  		ip->i_d.di_gid = pip->i_d.di_gid;
  		if ((pip->i_d.di_mode & S_ISGID) && S_ISDIR(mode)) {
  			ip->i_d.di_mode |= S_ISGID;
  		}
  	}
  
  	/*
  	 * If the group ID of the new file does not match the effective group
  	 * ID or one of the supplementary group IDs, the S_ISGID bit is cleared
  	 * (and only if the irix_sgid_inherit compatibility variable is set).
  	 */
  	if ((irix_sgid_inherit) &&
  	    (ip->i_d.di_mode & S_ISGID) &&
  	    (!in_group_p(xfs_gid_to_kgid(ip->i_d.di_gid)))) {
  		ip->i_d.di_mode &= ~S_ISGID;
  	}
  
  	ip->i_d.di_size = 0;
  	ip->i_d.di_nextents = 0;
  	ASSERT(ip->i_d.di_nblocks == 0);
  
  	nanotime(&tv);
  	ip->i_d.di_mtime.t_sec = (__int32_t)tv.tv_sec;
  	ip->i_d.di_mtime.t_nsec = (__int32_t)tv.tv_nsec;
  	ip->i_d.di_atime = ip->i_d.di_mtime;
  	ip->i_d.di_ctime = ip->i_d.di_mtime;
  
  	/*
  	 * di_gen will have been taken care of in xfs_iread.
  	 */
  	ip->i_d.di_extsize = 0;
  	ip->i_d.di_dmevmask = 0;
  	ip->i_d.di_dmstate = 0;
  	ip->i_d.di_flags = 0;
  
  	if (ip->i_d.di_version == 3) {
  		ASSERT(ip->i_d.di_ino == ino);
  		ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_uuid));
  		ip->i_d.di_crc = 0;
  		ip->i_d.di_changecount = 1;
  		ip->i_d.di_lsn = 0;
  		ip->i_d.di_flags2 = 0;
  		memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
  		ip->i_d.di_crtime = ip->i_d.di_mtime;
  	}
  
  
  	flags = XFS_ILOG_CORE;
  	switch (mode & S_IFMT) {
  	case S_IFIFO:
  	case S_IFCHR:
  	case S_IFBLK:
  	case S_IFSOCK:
  		ip->i_d.di_format = XFS_DINODE_FMT_DEV;
  		ip->i_df.if_u2.if_rdev = rdev;
  		ip->i_df.if_flags = 0;
  		flags |= XFS_ILOG_DEV;
  		break;
  	case S_IFREG:
  		/*
  		 * we can't set up filestreams until after the VFS inode
  		 * is set up properly.
  		 */
  		if (pip && xfs_inode_is_filestream(pip))
  			filestreams = 1;
  		/* fall through */
  	case S_IFDIR:
  		if (pip && (pip->i_d.di_flags & XFS_DIFLAG_ANY)) {
  			uint	di_flags = 0;
  
  			if (S_ISDIR(mode)) {
  				if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
  					di_flags |= XFS_DIFLAG_RTINHERIT;
  				if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
  					di_flags |= XFS_DIFLAG_EXTSZINHERIT;
  					ip->i_d.di_extsize = pip->i_d.di_extsize;
  				}
  			} else if (S_ISREG(mode)) {
  				if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
  					di_flags |= XFS_DIFLAG_REALTIME;
  				if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
  					di_flags |= XFS_DIFLAG_EXTSIZE;
  					ip->i_d.di_extsize = pip->i_d.di_extsize;
  				}
  			}
  			if ((pip->i_d.di_flags & XFS_DIFLAG_NOATIME) &&
  			    xfs_inherit_noatime)
  				di_flags |= XFS_DIFLAG_NOATIME;
  			if ((pip->i_d.di_flags & XFS_DIFLAG_NODUMP) &&
  			    xfs_inherit_nodump)
  				di_flags |= XFS_DIFLAG_NODUMP;
  			if ((pip->i_d.di_flags & XFS_DIFLAG_SYNC) &&
  			    xfs_inherit_sync)
  				di_flags |= XFS_DIFLAG_SYNC;
  			if ((pip->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) &&
  			    xfs_inherit_nosymlinks)
  				di_flags |= XFS_DIFLAG_NOSYMLINKS;
  			if (pip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
  				di_flags |= XFS_DIFLAG_PROJINHERIT;
  			if ((pip->i_d.di_flags & XFS_DIFLAG_NODEFRAG) &&
  			    xfs_inherit_nodefrag)
  				di_flags |= XFS_DIFLAG_NODEFRAG;
  			if (pip->i_d.di_flags & XFS_DIFLAG_FILESTREAM)
  				di_flags |= XFS_DIFLAG_FILESTREAM;
  			ip->i_d.di_flags |= di_flags;
  		}
  		/* FALLTHROUGH */
  	case S_IFLNK:
  		ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
  		ip->i_df.if_flags = XFS_IFEXTENTS;
  		ip->i_df.if_bytes = ip->i_df.if_real_bytes = 0;
  		ip->i_df.if_u1.if_extents = NULL;
  		break;
  	default:
  		ASSERT(0);
  	}
  	/*
  	 * Attribute fork settings for new inode.
  	 */
  	ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
  	ip->i_d.di_anextents = 0;
  
  	/*
  	 * Log the new values stuffed into the inode.
  	 */
  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
  	xfs_trans_log_inode(tp, ip, flags);
  
  	/* now that we have an i_mode we can setup inode ops and unlock */
  	xfs_setup_inode(ip);
  
  	/* now we have set up the vfs inode we can associate the filestream */
  	if (filestreams) {
  		error = xfs_filestream_associate(pip, ip);
  		if (error < 0)
  			return -error;
  		if (!error)
  			xfs_iflags_set(ip, XFS_IFILESTREAM);
  	}
  
  	*ipp = ip;
  	return 0;
  }
  
  /*
   * 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. */
  	umode_t		mode,
  	xfs_nlink_t	nlink,
  	xfs_dev_t	rdev,
  	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;
  	int		code;
  	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, prid, okalloc,
  			  &ialloc_context, &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 (!ialloc_context && !ip) {
  		*ipp = NULL;
  		return XFS_ERROR(ENOSPC);
  	}
  
  	/*
  	 * If the AGI buffer is non-NULL, 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 (ialloc_context) {
  		struct xfs_trans_res tres;
  
  		/*
  		 * 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.
  		 */
  		tres.tr_logres = xfs_trans_get_log_res(tp);
  		tres.tr_logcount = 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);
  			}
  			*tpp = ntp;
  			*ipp = NULL;
  			return code;
  		}
  
  		/*
  		 * transaction commit worked ok so we can drop the extra ticket
  		 * reference that we gained in xfs_trans_dup()
  		 */
  		xfs_log_ticket_put(tp->t_ticket);
  		tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
  		code = xfs_trans_reserve(tp, &tres, 0, 0);
  
  		/*
  		 * 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, prid,
  				  okalloc, &ialloc_context, &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(!ialloc_context && ip);
  
  	} 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_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
  
  	ASSERT (ip->i_d.di_nlink > 0);
  	ip->i_d.di_nlink--;
  	drop_nlink(VFS_I(ip));
  	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 == 1);
  
  	ip->i_d.di_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)
  {
  	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
  
  	ASSERT(ip->i_d.di_nlink > 0);
  	ip->i_d.di_nlink++;
  	inc_nlink(VFS_I(ip));
  	if ((ip->i_d.di_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;
  }
  
  int
  xfs_create(
  	xfs_inode_t		*dp,
  	struct xfs_name		*name,
  	umode_t			mode,
  	xfs_dev_t		rdev,
  	xfs_inode_t		**ipp)
  {
  	int			is_dir = S_ISDIR(mode);
  	struct xfs_mount	*mp = dp->i_mount;
  	struct xfs_inode	*ip = NULL;
  	struct xfs_trans	*tp = NULL;
  	int			error;
  	xfs_bmap_free_t		free_list;
  	xfs_fsblock_t		first_block;
  	bool                    unlock_dp_on_error = false;
  	uint			cancel_flags;
  	int			committed;
  	prid_t			prid;
  	struct xfs_dquot	*udqp = NULL;
  	struct xfs_dquot	*gdqp = NULL;
  	struct xfs_dquot	*pdqp = NULL;
  	struct xfs_trans_res	tres;
  	uint			resblks;
  
  	trace_xfs_create(dp, name);
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return XFS_ERROR(EIO);
  
  	if (dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
  		prid = xfs_get_projid(dp);
  	else
  		prid = XFS_PROJID_DEFAULT;
  
  	/*
  	 * Make sure that we have allocated dquot(s) on disk.
  	 */
  	error = xfs_qm_vop_dqalloc(dp, xfs_kuid_to_uid(current_fsuid()),
  					xfs_kgid_to_gid(current_fsgid()), prid,
  					XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
  					&udqp, &gdqp, &pdqp);
  	if (error)
  		return error;
  
  	if (is_dir) {
  		rdev = 0;
  		resblks = XFS_MKDIR_SPACE_RES(mp, name->len);
  		tres.tr_logres = M_RES(mp)->tr_mkdir.tr_logres;
  		tres.tr_logcount = XFS_MKDIR_LOG_COUNT;
  		tp = xfs_trans_alloc(mp, XFS_TRANS_MKDIR);
  	} else {
  		resblks = XFS_CREATE_SPACE_RES(mp, name->len);
  		tres.tr_logres = M_RES(mp)->tr_create.tr_logres;
  		tres.tr_logcount = XFS_CREATE_LOG_COUNT;
  		tp = xfs_trans_alloc(mp, XFS_TRANS_CREATE);
  	}
  
  	cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
  
  	/*
  	 * Initially assume that the file does not exist and
  	 * reserve the resources for that case.  If that is not
  	 * the case we'll drop the one we have and get a more
  	 * appropriate transaction later.
  	 */
  	tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
  	error = xfs_trans_reserve(tp, &tres, resblks, 0);
  	if (error == ENOSPC) {
  		/* flush outstanding delalloc blocks and retry */
  		xfs_flush_inodes(mp);
  		error = xfs_trans_reserve(tp, &tres, resblks, 0);
  	}
  	if (error == ENOSPC) {
  		/* No space at all so try a "no-allocation" reservation */
  		resblks = 0;
  		error = xfs_trans_reserve(tp, &tres, 0, 0);
  	}
  	if (error) {
  		cancel_flags = 0;
  		goto out_trans_cancel;
  	}
  
  	xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
  	unlock_dp_on_error = true;
  
  	xfs_bmap_init(&free_list, &first_block);
  
  	/*
  	 * Reserve disk quota and the inode.
  	 */
  	error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
  						pdqp, resblks, 1, 0);
  	if (error)
  		goto out_trans_cancel;
  
  	error = xfs_dir_canenter(tp, dp, name, resblks);
  	if (error)
  		goto out_trans_cancel;
  
  	/*
  	 * A newly created regular or special file just has one directory
  	 * entry pointing to them, but a directory also the "." entry
  	 * pointing to itself.
  	 */
  	error = xfs_dir_ialloc(&tp, dp, mode, is_dir ? 2 : 1, rdev,
  			       prid, resblks > 0, &ip, &committed);
  	if (error) {
  		if (error == ENOSPC)
  			goto out_trans_cancel;
  		goto out_trans_abort;
  	}
  
  	/*
  	 * Now we join the directory inode to the transaction.  We do not do it
  	 * earlier because xfs_dir_ialloc might commit the previous transaction
  	 * (and release all the locks).  An error from here on will result in
  	 * the transaction cancel unlocking dp so don't do it explicitly in the
  	 * error path.
  	 */
  	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
  	unlock_dp_on_error = false;
  
  	error = xfs_dir_createname(tp, dp, name, ip->i_ino,
  					&first_block, &free_list, resblks ?
  					resblks - XFS_IALLOC_SPACE_RES(mp) : 0);
  	if (error) {
  		ASSERT(error != ENOSPC);
  		goto out_trans_abort;
  	}
  	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
  
  	if (is_dir) {
  		error = xfs_dir_init(tp, ip, dp);
  		if (error)
  			goto out_bmap_cancel;
  
  		error = xfs_bumplink(tp, dp);
  		if (error)
  			goto out_bmap_cancel;
  	}
  
  	/*
  	 * If this is a synchronous mount, make sure that the
  	 * create transaction goes to disk before returning to
  	 * the user.
  	 */
  	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC))
  		xfs_trans_set_sync(tp);
  
  	/*
  	 * Attach the dquot(s) to the inodes and modify them incore.
  	 * These ids of the inode couldn't have changed since the new
  	 * inode has been locked ever since it was created.
  	 */
  	xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
  
  	error = xfs_bmap_finish(&tp, &free_list, &committed);
  	if (error)
  		goto out_bmap_cancel;
  
  	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
  	if (error)
  		goto out_release_inode;
  
  	xfs_qm_dqrele(udqp);
  	xfs_qm_dqrele(gdqp);
  	xfs_qm_dqrele(pdqp);
  
  	*ipp = ip;
  	return 0;
  
   out_bmap_cancel:
  	xfs_bmap_cancel(&free_list);
   out_trans_abort:
  	cancel_flags |= XFS_TRANS_ABORT;
   out_trans_cancel:
  	xfs_trans_cancel(tp, cancel_flags);
   out_release_inode:
  	/*
  	 * Wait until after the current transaction is aborted to
  	 * release the inode.  This prevents recursive transactions
  	 * and deadlocks from xfs_inactive.
  	 */
  	if (ip)
  		IRELE(ip);
  
  	xfs_qm_dqrele(udqp);
  	xfs_qm_dqrele(gdqp);
  	xfs_qm_dqrele(pdqp);
  
  	if (unlock_dp_on_error)
  		xfs_iunlock(dp, XFS_ILOCK_EXCL);
  	return error;
  }
  
  int
  xfs_link(
  	xfs_inode_t		*tdp,
  	xfs_inode_t		*sip,
  	struct xfs_name		*target_name)
  {
  	xfs_mount_t		*mp = tdp->i_mount;
  	xfs_trans_t		*tp;
  	int			error;
  	xfs_bmap_free_t         free_list;
  	xfs_fsblock_t           first_block;
  	int			cancel_flags;
  	int			committed;
  	int			resblks;
  
  	trace_xfs_link(tdp, target_name);
  
  	ASSERT(!S_ISDIR(sip->i_d.di_mode));
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return XFS_ERROR(EIO);
  
  	error = xfs_qm_dqattach(sip, 0);
  	if (error)
  		goto std_return;
  
  	error = xfs_qm_dqattach(tdp, 0);
  	if (error)
  		goto std_return;
  
  	tp = xfs_trans_alloc(mp, XFS_TRANS_LINK);
  	cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
  	resblks = XFS_LINK_SPACE_RES(mp, target_name->len);
  	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_link, resblks, 0);
  	if (error == ENOSPC) {
  		resblks = 0;
  		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_link, 0, 0);
  	}
  	if (error) {
  		cancel_flags = 0;
  		goto error_return;
  	}
  
  	xfs_lock_two_inodes(sip, tdp, XFS_ILOCK_EXCL);
  
  	xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);
  
  	/*
  	 * If we are using project inheritance, we only allow hard link
  	 * creation in our tree when the project IDs are the same; else
  	 * the tree quota mechanism could be circumvented.
  	 */
  	if (unlikely((tdp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
  		     (xfs_get_projid(tdp) != xfs_get_projid(sip)))) {
  		error = XFS_ERROR(EXDEV);
  		goto error_return;
  	}
  
  	error = xfs_dir_canenter(tp, tdp, target_name, resblks);
  	if (error)
  		goto error_return;
  
  	xfs_bmap_init(&free_list, &first_block);
  
  	error = xfs_dir_createname(tp, tdp, target_name, sip->i_ino,
  					&first_block, &free_list, resblks);
  	if (error)
  		goto abort_return;
  	xfs_trans_ichgtime(tp, tdp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);
  
  	error = xfs_bumplink(tp, sip);
  	if (error)
  		goto abort_return;
  
  	/*
  	 * If this is a synchronous mount, make sure that the
  	 * link transaction goes to disk before returning to
  	 * the user.
  	 */
  	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
  		xfs_trans_set_sync(tp);
  	}
  
  	error = xfs_bmap_finish (&tp, &free_list, &committed);
  	if (error) {
  		xfs_bmap_cancel(&free_list);
  		goto abort_return;
  	}
  
  	return xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
  
   abort_return:
  	cancel_flags |= XFS_TRANS_ABORT;
   error_return:
  	xfs_trans_cancel(tp, cancel_flags);
   std_return:
  	return error;
  }
  
  /*
   * Free up the underlying blocks past new_size.  The new size must be smaller
   * than the current size.  This routine can be used both for the attribute and
   * data fork, and does not modify the inode size, which is left to the caller.
   *
   * The transaction passed to this routine must have made a permanent log
   * reservation of at least XFS_ITRUNCATE_LOG_RES.  This routine may commit the
   * given transaction and start new ones, so make sure everything involved in
   * the transaction is tidy before calling here.  Some transaction will be
   * returned to the caller to be committed.  The incoming transaction must
   * already include the inode, and both inode locks must be held exclusively.
   * The inode must also be "held" within the transaction.  On return the inode
   * will be "held" within the returned transaction.  This routine does NOT
   * require any disk space to be reserved for it within the transaction.
   *
   * If we get an error, we must return with the inode locked and linked into the
   * current transaction. This keeps things simple for the higher level code,
   * because it always knows that the inode is locked and held in the transaction
   * that returns to it whether errors occur or not.  We don't mark the inode
   * dirty on error so that transactions can be easily aborted if possible.
   */
  int
  xfs_itruncate_extents(
  	struct xfs_trans	**tpp,
  	struct xfs_inode	*ip,
  	int			whichfork,
  	xfs_fsize_t		new_size)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_trans	*tp = *tpp;
  	struct xfs_trans	*ntp;
  	xfs_bmap_free_t		free_list;
  	xfs_fsblock_t		first_block;
  	xfs_fileoff_t		first_unmap_block;
  	xfs_fileoff_t		last_block;
  	xfs_filblks_t		unmap_len;
  	int			committed;
  	int			error = 0;
  	int			done = 0;
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(!atomic_read(&VFS_I(ip)->i_count) ||
  	       xfs_isilocked(ip, XFS_IOLOCK_EXCL));
  	ASSERT(new_size <= XFS_ISIZE(ip));
  	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
  	ASSERT(ip->i_itemp != NULL);
  	ASSERT(ip->i_itemp->ili_lock_flags == 0);
  	ASSERT(!XFS_NOT_DQATTACHED(mp, ip));
  
  	trace_xfs_itruncate_extents_start(ip, new_size);
  
  	/*
  	 * Since it is possible for space to become allocated beyond
  	 * the end of the file (in a crash where the space is allocated
  	 * but the inode size is not yet updated), simply remove any
  	 * blocks which show up between the new EOF and the maximum
  	 * possible file size.  If the first block to be removed is
  	 * beyond the maximum file size (ie it is the same as last_block),
  	 * then there is nothing to do.
  	 */
  	first_unmap_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
  	last_block = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
  	if (first_unmap_block == last_block)
  		return 0;
  
  	ASSERT(first_unmap_block < last_block);
  	unmap_len = last_block - first_unmap_block + 1;
  	while (!done) {
  		xfs_bmap_init(&free_list, &first_block);
  		error = xfs_bunmapi(tp, ip,
  				    first_unmap_block, unmap_len,
  				    xfs_bmapi_aflag(whichfork),
  				    XFS_ITRUNC_MAX_EXTENTS,
  				    &first_block, &free_list,
  				    &done);
  		if (error)
  			goto out_bmap_cancel;
  
  		/*
  		 * Duplicate the transaction that has the permanent
  		 * reservation and commit the old transaction.
  		 */
  		error = xfs_bmap_finish(&tp, &free_list, &committed);
  		if (committed)
  			xfs_trans_ijoin(tp, ip, 0);
  		if (error)
  			goto out_bmap_cancel;
  
  		if (committed) {
  			/*
  			 * Mark the inode dirty so it will be logged and
  			 * moved forward in the log as part of every commit.
  			 */
  			xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  		}
  
  		ntp = xfs_trans_dup(tp);
  		error = xfs_trans_commit(tp, 0);
  		tp = ntp;
  
  		xfs_trans_ijoin(tp, ip, 0);
  
  		if (error)
  			goto out;
  
  		/*
  		 * Transaction commit worked ok so we can drop the extra ticket
  		 * reference that we gained in xfs_trans_dup()
  		 */
  		xfs_log_ticket_put(tp->t_ticket);
  		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
  		if (error)
  			goto out;
  	}
  
  	/*
  	 * Always re-log the inode so that our permanent transaction can keep
  	 * on rolling it forward in the log.
  	 */
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	trace_xfs_itruncate_extents_end(ip, new_size);
  
  out:
  	*tpp = tp;
  	return error;
  out_bmap_cancel:
  	/*
  	 * If the bunmapi call encounters an error, return to the caller where
  	 * the transaction can be properly aborted.  We just need to make sure
  	 * we're not holding any resources that we were not when we came in.
  	 */
  	xfs_bmap_cancel(&free_list);
  	goto out;
  }
  
  int
  xfs_release(
  	xfs_inode_t	*ip)
  {
  	xfs_mount_t	*mp = ip->i_mount;
  	int		error;
  
  	if (!S_ISREG(ip->i_d.di_mode) || (ip->i_d.di_mode == 0))
  		return 0;
  
  	/* If this is a read-only mount, don't do this (would generate I/O) */
  	if (mp->m_flags & XFS_MOUNT_RDONLY)
  		return 0;
  
  	if (!XFS_FORCED_SHUTDOWN(mp)) {
  		int truncated;
  
  		/*
  		 * If we are using filestreams, and we have an unlinked
  		 * file that we are processing the last close on, then nothing
  		 * will be able to reopen and write to this file. Purge this
  		 * inode from the filestreams cache so that it doesn't delay
  		 * teardown of the inode.
  		 */
  		if ((ip->i_d.di_nlink == 0) && xfs_inode_is_filestream(ip))
  			xfs_filestream_deassociate(ip);
  
  		/*
  		 * If we previously truncated this file and removed old data
  		 * in the process, we want to initiate "early" writeout on
  		 * the last close.  This is an attempt to combat the notorious
  		 * NULL files problem which is particularly noticeable from a
  		 * truncate down, buffered (re-)write (delalloc), followed by
  		 * a crash.  What we are effectively doing here is
  		 * significantly reducing the time window where we'd otherwise
  		 * be exposed to that problem.
  		 */
  		truncated = xfs_iflags_test_and_clear(ip, XFS_ITRUNCATED);
  		if (truncated) {
  			xfs_iflags_clear(ip, XFS_IDIRTY_RELEASE);
  			if (VN_DIRTY(VFS_I(ip)) && ip->i_delayed_blks > 0) {
  				error = -filemap_flush(VFS_I(ip)->i_mapping);
  				if (error)
  					return error;
  			}
  		}
  	}
  
  	if (ip->i_d.di_nlink == 0)
  		return 0;
  
  	if (xfs_can_free_eofblocks(ip, false)) {
  
  		/*
  		 * If we can't get the iolock just skip truncating the blocks
  		 * past EOF because we could deadlock with the mmap_sem
  		 * otherwise.  We'll get another chance to drop them once the
  		 * last reference to the inode is dropped, so we'll never leak
  		 * blocks permanently.
  		 *
  		 * Further, check if the inode is being opened, written and
  		 * closed frequently and we have delayed allocation blocks
  		 * outstanding (e.g. streaming writes from the NFS server),
  		 * truncating the blocks past EOF will cause fragmentation to
  		 * occur.
  		 *
  		 * In this case don't do the truncation, either, but we have to
  		 * be careful how we detect this case. Blocks beyond EOF show
  		 * up as i_delayed_blks even when the inode is clean, so we
  		 * need to truncate them away first before checking for a dirty
  		 * release. Hence on the first dirty close we will still remove
  		 * the speculative allocation, but after that we will leave it
  		 * in place.
  		 */
  		if (xfs_iflags_test(ip, XFS_IDIRTY_RELEASE))
  			return 0;
  
  		error = xfs_free_eofblocks(mp, ip, true);
  		if (error && error != EAGAIN)
  			return error;
  
  		/* delalloc blocks after truncation means it really is dirty */
  		if (ip->i_delayed_blks)
  			xfs_iflags_set(ip, XFS_IDIRTY_RELEASE);
  	}
  	return 0;
  }
  
  /*
   * xfs_inactive_truncate
   *
   * Called to perform a truncate when an inode becomes unlinked.
   */
  STATIC int
  xfs_inactive_truncate(
  	struct xfs_inode *ip)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_trans	*tp;
  	int			error;
  
  	tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
  	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
  	if (error) {
  		ASSERT(XFS_FORCED_SHUTDOWN(mp));
  		xfs_trans_cancel(tp, 0);
  		return error;
  	}
  
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, 0);
  
  	/*
  	 * Log the inode size first to prevent stale data exposure in the event
  	 * of a system crash before the truncate completes. See the related
  	 * comment in xfs_setattr_size() for details.
  	 */
  	ip->i_d.di_size = 0;
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK, 0);
  	if (error)
  		goto error_trans_cancel;
  
  	ASSERT(ip->i_d.di_nextents == 0);
  
  	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
  	if (error)
  		goto error_unlock;
  
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return 0;
  
  error_trans_cancel:
  	xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
  error_unlock:
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return error;
  }
  
  /*
   * xfs_inactive_ifree()
   *
   * Perform the inode free when an inode is unlinked.
   */
  STATIC int
  xfs_inactive_ifree(
  	struct xfs_inode *ip)
  {
  	xfs_bmap_free_t		free_list;
  	xfs_fsblock_t		first_block;
  	int			committed;
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_trans	*tp;
  	int			error;
  
  	tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
  	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ifree, 0, 0);
  	if (error) {
  		ASSERT(XFS_FORCED_SHUTDOWN(mp));
  		xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES);
  		return error;
  	}
  
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, 0);
  
  	xfs_bmap_init(&free_list, &first_block);
  	error = xfs_ifree(tp, ip, &free_list);
  	if (error) {
  		/*
  		 * If we fail to free the inode, shut down.  The cancel
  		 * might do that, we need to make sure.  Otherwise the
  		 * inode might be lost for a long time or forever.
  		 */
  		if (!XFS_FORCED_SHUTDOWN(mp)) {
  			xfs_notice(mp, "%s: xfs_ifree returned error %d",
  				__func__, error);
  			xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
  		}
  		xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES|XFS_TRANS_ABORT);
  		xfs_iunlock(ip, XFS_ILOCK_EXCL);
  		return error;
  	}
  
  	/*
  	 * Credit the quota account(s). The inode is gone.
  	 */
  	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_ICOUNT, -1);
  
  	/*
  	 * Just ignore errors at this point.  There is nothing we can
  	 * do except to try to keep going. Make sure it's not a silent
  	 * error.
  	 */
  	error = xfs_bmap_finish(&tp,  &free_list, &committed);
  	if (error)
  		xfs_notice(mp, "%s: xfs_bmap_finish returned error %d",
  			__func__, error);
  	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
  	if (error)
  		xfs_notice(mp, "%s: xfs_trans_commit returned error %d",
  			__func__, error);
  
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return 0;
  }
  
  /*
   * xfs_inactive
   *
   * This is called when the vnode reference count for the vnode
   * goes to zero.  If the file has been unlinked, then it must
   * now be truncated.  Also, we clear all of the read-ahead state
   * kept for the inode here since the file is now closed.
   */
  void
  xfs_inactive(
  	xfs_inode_t	*ip)
  {
  	struct xfs_mount	*mp;
  	int			error;
  	int			truncate = 0;
  
  	/*
  	 * If the inode is already free, then there can be nothing
  	 * to clean up here.
  	 */
  	if (ip->i_d.di_mode == 0) {
  		ASSERT(ip->i_df.if_real_bytes == 0);
  		ASSERT(ip->i_df.if_broot_bytes == 0);
  		return;
  	}
  
  	mp = ip->i_mount;
  
  	/* If this is a read-only mount, don't do this (would generate I/O) */
  	if (mp->m_flags & XFS_MOUNT_RDONLY)
  		return;
  
  	if (ip->i_d.di_nlink != 0) {
  		/*
  		 * force is true because we are evicting an inode from the
  		 * cache. Post-eof blocks must be freed, lest we end up with
  		 * broken free space accounting.
  		 */
  		if (xfs_can_free_eofblocks(ip, true))
  			xfs_free_eofblocks(mp, ip, false);
  
  		return;
  	}
  
  	if (S_ISREG(ip->i_d.di_mode) &&
  	    (ip->i_d.di_size != 0 || XFS_ISIZE(ip) != 0 ||
  	     ip->i_d.di_nextents > 0 || ip->i_delayed_blks > 0))
  		truncate = 1;
  
  	error = xfs_qm_dqattach(ip, 0);
  	if (error)
  		return;
  
  	if (S_ISLNK(ip->i_d.di_mode))
  		error = xfs_inactive_symlink(ip);
  	else if (truncate)
  		error = xfs_inactive_truncate(ip);
  	if (error)
  		return;
  
  	/*
  	 * If there are attributes associated with the file then blow them away
  	 * now.  The code calls a routine that recursively deconstructs the
  	 * attribute fork.  We need to just commit the current transaction
  	 * because we can't use it for xfs_attr_inactive().
  	 */
  	if (ip->i_d.di_anextents > 0) {
  		ASSERT(ip->i_d.di_forkoff != 0);
  
  		error = xfs_attr_inactive(ip);
  		if (error)
  			return;
  	}
  
  	if (ip->i_afp)
  		xfs_idestroy_fork(ip, XFS_ATTR_FORK);
  
  	ASSERT(ip->i_d.di_anextents == 0);
  
  	/*
  	 * Free the inode.
  	 */
  	error = xfs_inactive_ifree(ip);
  	if (error)
  		return;
  
  	/*
  	 * Release the dquots held by inode, if any.
  	 */
  	xfs_qm_dqdetach(ip);
  }
  
  /*
   * This is called when the inode's link count goes to 0.
   * We place the on-disk inode on a list in the AGI.  It
   * will be pulled from this list when the inode is freed.
   */
  int
  xfs_iunlink(
  	xfs_trans_t	*tp,
  	xfs_inode_t	*ip)
  {
  	xfs_mount_t	*mp;
  	xfs_agi_t	*agi;
  	xfs_dinode_t	*dip;
  	xfs_buf_t	*agibp;
  	xfs_buf_t	*ibp;
  	xfs_agino_t	agino;
  	short		bucket_index;
  	int		offset;
  	int		error;
  
  	ASSERT(ip->i_d.di_nlink == 0);
  	ASSERT(ip->i_d.di_mode != 0);
  
  	mp = tp->t_mountp;
  
  	/*
  	 * Get the agi buffer first.  It ensures lock ordering
  	 * on the list.
  	 */
  	error = xfs_read_agi(mp, tp, XFS_INO_TO_AGNO(mp, ip->i_ino), &agibp);
  	if (error)
  		return error;
  	agi = XFS_BUF_TO_AGI(agibp);
  
  	/*
  	 * Get the index into the agi hash table for the
  	 * list this inode will go on.
  	 */
  	agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
  	ASSERT(agino != 0);
  	bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
  	ASSERT(agi->agi_unlinked[bucket_index]);
  	ASSERT(be32_to_cpu(agi->agi_unlinked[bucket_index]) != agino);
  
  	if (agi->agi_unlinked[bucket_index] != cpu_to_be32(NULLAGINO)) {
  		/*
  		 * There is already another inode in the bucket we need
  		 * to add ourselves to.  Add us at the front of the list.
  		 * Here we put the head pointer into our next pointer,
  		 * and then we fall through to point the head at us.
  		 */
  		error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
  				       0, 0);
  		if (error)
  			return error;
  
  		ASSERT(dip->di_next_unlinked == cpu_to_be32(NULLAGINO));
  		dip->di_next_unlinked = agi->agi_unlinked[bucket_index];
  		offset = ip->i_imap.im_boffset +
  			offsetof(xfs_dinode_t, di_next_unlinked);
  
  		/* need to recalc the inode CRC if appropriate */
  		xfs_dinode_calc_crc(mp, dip);
  
  		xfs_trans_inode_buf(tp, ibp);
  		xfs_trans_log_buf(tp, ibp, offset,
  				  (offset + sizeof(xfs_agino_t) - 1));
  		xfs_inobp_check(mp, ibp);
  	}
  
  	/*
  	 * Point the bucket head pointer at the inode being inserted.
  	 */
  	ASSERT(agino != 0);
  	agi->agi_unlinked[bucket_index] = cpu_to_be32(agino);
  	offset = offsetof(xfs_agi_t, agi_unlinked) +
  		(sizeof(xfs_agino_t) * bucket_index);
  	xfs_trans_log_buf(tp, agibp, offset,
  			  (offset + sizeof(xfs_agino_t) - 1));
  	return 0;
  }
  
  /*
   * Pull the on-disk inode from the AGI unlinked list.
   */
  STATIC int
  xfs_iunlink_remove(
  	xfs_trans_t	*tp,
  	xfs_inode_t	*ip)
  {
  	xfs_ino_t	next_ino;
  	xfs_mount_t	*mp;
  	xfs_agi_t	*agi;
  	xfs_dinode_t	*dip;
  	xfs_buf_t	*agibp;
  	xfs_buf_t	*ibp;
  	xfs_agnumber_t	agno;
  	xfs_agino_t	agino;
  	xfs_agino_t	next_agino;
  	xfs_buf_t	*last_ibp;
  	xfs_dinode_t	*last_dip = NULL;
  	short		bucket_index;
  	int		offset, last_offset = 0;
  	int		error;
  
  	mp = tp->t_mountp;
  	agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
  
  	/*
  	 * Get the agi buffer first.  It ensures lock ordering
  	 * on the list.
  	 */
  	error = xfs_read_agi(mp, tp, agno, &agibp);
  	if (error)
  		return error;
  
  	agi = XFS_BUF_TO_AGI(agibp);
  
  	/*
  	 * Get the index into the agi hash table for the
  	 * list this inode will go on.
  	 */
  	agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
  	ASSERT(agino != 0);
  	bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
  	ASSERT(agi->agi_unlinked[bucket_index] != cpu_to_be32(NULLAGINO));
  	ASSERT(agi->agi_unlinked[bucket_index]);
  
  	if (be32_to_cpu(agi->agi_unlinked[bucket_index]) == agino) {
  		/*
  		 * We're at the head of the list.  Get the inode's on-disk
  		 * buffer to see if there is anyone after us on the list.
  		 * Only modify our next pointer if it is not already NULLAGINO.
  		 * This saves us the overhead of dealing with the buffer when
  		 * there is no need to change it.
  		 */
  		error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
  				       0, 0);
  		if (error) {
  			xfs_warn(mp, "%s: xfs_imap_to_bp returned error %d.",
  				__func__, error);
  			return error;
  		}
  		next_agino = be32_to_cpu(dip->di_next_unlinked);
  		ASSERT(next_agino != 0);
  		if (next_agino != NULLAGINO) {
  			dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
  			offset = ip->i_imap.im_boffset +
  				offsetof(xfs_dinode_t, di_next_unlinked);
  
  			/* need to recalc the inode CRC if appropriate */
  			xfs_dinode_calc_crc(mp, dip);
  
  			xfs_trans_inode_buf(tp, ibp);
  			xfs_trans_log_buf(tp, ibp, offset,
  					  (offset + sizeof(xfs_agino_t) - 1));
  			xfs_inobp_check(mp, ibp);
  		} else {
  			xfs_trans_brelse(tp, ibp);
  		}
  		/*
  		 * Point the bucket head pointer at the next inode.
  		 */
  		ASSERT(next_agino != 0);
  		ASSERT(next_agino != agino);
  		agi->agi_unlinked[bucket_index] = cpu_to_be32(next_agino);
  		offset = offsetof(xfs_agi_t, agi_unlinked) +
  			(sizeof(xfs_agino_t) * bucket_index);
  		xfs_trans_log_buf(tp, agibp, offset,
  				  (offset + sizeof(xfs_agino_t) - 1));
  	} else {
  		/*
  		 * We need to search the list for the inode being freed.
  		 */
  		next_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
  		last_ibp = NULL;
  		while (next_agino != agino) {
  			struct xfs_imap	imap;
  
  			if (last_ibp)
  				xfs_trans_brelse(tp, last_ibp);
  
  			imap.im_blkno = 0;
  			next_ino = XFS_AGINO_TO_INO(mp, agno, next_agino);
  
  			error = xfs_imap(mp, tp, next_ino, &imap, 0);
  			if (error) {
  				xfs_warn(mp,
  	"%s: xfs_imap returned error %d.",
  					 __func__, error);
  				return error;
  			}
  
  			error = xfs_imap_to_bp(mp, tp, &imap, &last_dip,
  					       &last_ibp, 0, 0);
  			if (error) {
  				xfs_warn(mp,
  	"%s: xfs_imap_to_bp returned error %d.",
  					__func__, error);
  				return error;
  			}
  
  			last_offset = imap.im_boffset;
  			next_agino = be32_to_cpu(last_dip->di_next_unlinked);
  			ASSERT(next_agino != NULLAGINO);
  			ASSERT(next_agino != 0);
  		}
  
  		/*
  		 * Now last_ibp points to the buffer previous to us on the
  		 * unlinked list.  Pull us from the list.
  		 */
  		error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
  				       0, 0);
  		if (error) {
  			xfs_warn(mp, "%s: xfs_imap_to_bp(2) returned error %d.",
  				__func__, error);
  			return error;
  		}
  		next_agino = be32_to_cpu(dip->di_next_unlinked);
  		ASSERT(next_agino != 0);
  		ASSERT(next_agino != agino);
  		if (next_agino != NULLAGINO) {
  			dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
  			offset = ip->i_imap.im_boffset +
  				offsetof(xfs_dinode_t, di_next_unlinked);
  
  			/* need to recalc the inode CRC if appropriate */
  			xfs_dinode_calc_crc(mp, dip);
  
  			xfs_trans_inode_buf(tp, ibp);
  			xfs_trans_log_buf(tp, ibp, offset,
  					  (offset + sizeof(xfs_agino_t) - 1));
  			xfs_inobp_check(mp, ibp);
  		} else {
  			xfs_trans_brelse(tp, ibp);
  		}
  		/*
  		 * Point the previous inode on the list to the next inode.
  		 */
  		last_dip->di_next_unlinked = cpu_to_be32(next_agino);
  		ASSERT(next_agino != 0);
  		offset = last_offset + offsetof(xfs_dinode_t, di_next_unlinked);
  
  		/* need to recalc the inode CRC if appropriate */
  		xfs_dinode_calc_crc(mp, last_dip);
  
  		xfs_trans_inode_buf(tp, last_ibp);
  		xfs_trans_log_buf(tp, last_ibp, offset,
  				  (offset + sizeof(xfs_agino_t) - 1));
  		xfs_inobp_check(mp, last_ibp);
  	}
  	return 0;
  }
  
  /*
   * A big issue when freeing the inode cluster is that we _cannot_ skip any
   * inodes that are in memory - they all must be marked stale and attached to
   * the cluster buffer.
   */
  STATIC int
  xfs_ifree_cluster(
  	xfs_inode_t	*free_ip,
  	xfs_trans_t	*tp,
  	xfs_ino_t	inum)
  {
  	xfs_mount_t		*mp = free_ip->i_mount;
  	int			blks_per_cluster;
  	int			inodes_per_cluster;
  	int			nbufs;
  	int			i, j;
  	xfs_daddr_t		blkno;
  	xfs_buf_t		*bp;
  	xfs_inode_t		*ip;
  	xfs_inode_log_item_t	*iip;
  	xfs_log_item_t		*lip;
  	struct xfs_perag	*pag;
  
  	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, inum));
  	blks_per_cluster = xfs_icluster_size_fsb(mp);
  	inodes_per_cluster = blks_per_cluster << mp->m_sb.sb_inopblog;
  	nbufs = mp->m_ialloc_blks / blks_per_cluster;
  
  	for (j = 0; j < nbufs; j++, inum += inodes_per_cluster) {
  		blkno = XFS_AGB_TO_DADDR(mp, XFS_INO_TO_AGNO(mp, inum),
  					 XFS_INO_TO_AGBNO(mp, inum));
  
  		/*
  		 * We obtain and lock the backing buffer first in the process
  		 * here, as we have to ensure that any dirty inode that we
  		 * can't get the flush lock on is attached to the buffer.
  		 * If we scan the in-memory inodes first, then buffer IO can
  		 * complete before we get a lock on it, and hence we may fail
  		 * to mark all the active inodes on the buffer stale.
  		 */
  		bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, blkno,
  					mp->m_bsize * blks_per_cluster,
  					XBF_UNMAPPED);
  
  		if (!bp)
  			return ENOMEM;
  
  		/*
  		 * This buffer may not have been correctly initialised as we
  		 * didn't read it from disk. That's not important because we are
  		 * only using to mark the buffer as stale in the log, and to
  		 * attach stale cached inodes on it. That means it will never be
  		 * dispatched for IO. If it is, we want to know about it, and we
  		 * want it to fail. We can acheive this by adding a write
  		 * verifier to the buffer.
  		 */
  		 bp->b_ops = &xfs_inode_buf_ops;
  
  		/*
  		 * Walk the inodes already attached to the buffer and mark them
  		 * stale. These will all have the flush locks held, so an
  		 * in-memory inode walk can't lock them. By marking them all
  		 * stale first, we will not attempt to lock them in the loop
  		 * below as the XFS_ISTALE flag will be set.
  		 */
  		lip = bp->b_fspriv;
  		while (lip) {
  			if (lip->li_type == XFS_LI_INODE) {
  				iip = (xfs_inode_log_item_t *)lip;
  				ASSERT(iip->ili_logged == 1);
  				lip->li_cb = xfs_istale_done;
  				xfs_trans_ail_copy_lsn(mp->m_ail,
  							&iip->ili_flush_lsn,
  							&iip->ili_item.li_lsn);
  				xfs_iflags_set(iip->ili_inode, XFS_ISTALE);
  			}
  			lip = lip->li_bio_list;
  		}
  
  
  		/*
  		 * For each inode in memory attempt to add it to the inode
  		 * buffer and set it up for being staled on buffer IO
  		 * completion.  This is safe as we've locked out tail pushing
  		 * and flushing by locking the buffer.
  		 *
  		 * We have already marked every inode that was part of a
  		 * transaction stale above, which means there is no point in
  		 * even trying to lock them.
  		 */
  		for (i = 0; i < inodes_per_cluster; i++) {
  retry:
  			rcu_read_lock();
  			ip = radix_tree_lookup(&pag->pag_ici_root,
  					XFS_INO_TO_AGINO(mp, (inum + i)));
  
  			/* Inode not in memory, nothing to do */
  			if (!ip) {
  				rcu_read_unlock();
  				continue;
  			}
  
  			/*
  			 * because this is an RCU protected lookup, we could
  			 * find a recently freed or even reallocated inode
  			 * during the lookup. We need to check under the
  			 * i_flags_lock for a valid inode here. Skip it if it
  			 * is not valid, the wrong inode or stale.
  			 */
  			spin_lock(&ip->i_flags_lock);
  			if (ip->i_ino != inum + i ||
  			    __xfs_iflags_test(ip, XFS_ISTALE)) {
  				spin_unlock(&ip->i_flags_lock);
  				rcu_read_unlock();
  				continue;
  			}
  			spin_unlock(&ip->i_flags_lock);
  
  			/*
  			 * Don't try to lock/unlock the current inode, but we
  			 * _cannot_ skip the other inodes that we did not find
  			 * in the list attached to the buffer and are not
  			 * already marked stale. If we can't lock it, back off
  			 * and retry.
  			 */
  			if (ip != free_ip &&
  			    !xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
  				rcu_read_unlock();
  				delay(1);
  				goto retry;
  			}
  			rcu_read_unlock();
  
  			xfs_iflock(ip);
  			xfs_iflags_set(ip, XFS_ISTALE);
  
  			/*
  			 * we don't need to attach clean inodes or those only
  			 * with unlogged changes (which we throw away, anyway).
  			 */
  			iip = ip->i_itemp;
  			if (!iip || xfs_inode_clean(ip)) {
  				ASSERT(ip != free_ip);
  				xfs_ifunlock(ip);
  				xfs_iunlock(ip, XFS_ILOCK_EXCL);
  				continue;
  			}
  
  			iip->ili_last_fields = iip->ili_fields;
  			iip->ili_fields = 0;
  			iip->ili_logged = 1;
  			xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
  						&iip->ili_item.li_lsn);
  
  			xfs_buf_attach_iodone(bp, xfs_istale_done,
  						  &iip->ili_item);
  
  			if (ip != free_ip)
  				xfs_iunlock(ip, XFS_ILOCK_EXCL);
  		}
  
  		xfs_trans_stale_inode_buf(tp, bp);
  		xfs_trans_binval(tp, bp);
  	}
  
  	xfs_perag_put(pag);
  	return 0;
  }
  
  /*
   * This is called to return an inode to the inode free list.
   * The inode should already be truncated to 0 length and have
   * no pages associated with it.  This routine also assumes that
   * the inode is already a part of the transaction.
   *
   * The on-disk copy of the inode will have been added to the list
   * of unlinked inodes in the AGI. We need to remove the inode from
   * that list atomically with respect to freeing it here.
   */
  int
  xfs_ifree(
  	xfs_trans_t	*tp,
  	xfs_inode_t	*ip,
  	xfs_bmap_free_t	*flist)
  {
  	int			error;
  	int			delete;
  	xfs_ino_t		first_ino;
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(ip->i_d.di_nlink == 0);
  	ASSERT(ip->i_d.di_nextents == 0);
  	ASSERT(ip->i_d.di_anextents == 0);
  	ASSERT(ip->i_d.di_size == 0 || !S_ISREG(ip->i_d.di_mode));
  	ASSERT(ip->i_d.di_nblocks == 0);
  
  	/*
  	 * Pull the on-disk inode from the AGI unlinked list.
  	 */
  	error = xfs_iunlink_remove(tp, ip);
  	if (error)
  		return error;
  
  	error = xfs_difree(tp, ip->i_ino, flist, &delete, &first_ino);
  	if (error)
  		return error;
  
  	ip->i_d.di_mode = 0;		/* mark incore inode as free */
  	ip->i_d.di_flags = 0;
  	ip->i_d.di_dmevmask = 0;
  	ip->i_d.di_forkoff = 0;		/* mark the attr fork not in use */
  	ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
  	ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
  	/*
  	 * Bump the generation count so no one will be confused
  	 * by reincarnations of this inode.
  	 */
  	ip->i_d.di_gen++;
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	if (delete)
  		error = xfs_ifree_cluster(ip, tp, first_ino);
  
  	return error;
  }
  
  /*
   * This is called to unpin an inode.  The caller must have the inode locked
   * in at least shared mode so that the buffer cannot be subsequently pinned
   * once someone is waiting for it to be unpinned.
   */
  static void
  xfs_iunpin(
  	struct xfs_inode	*ip)
  {
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
  
  	trace_xfs_inode_unpin_nowait(ip, _RET_IP_);
  
  	/* Give the log a push to start the unpinning I/O */
  	xfs_log_force_lsn(ip->i_mount, ip->i_itemp->ili_last_lsn, 0);
  
  }
  
  static void
  __xfs_iunpin_wait(
  	struct xfs_inode	*ip)
  {
  	wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IPINNED_BIT);
  	DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IPINNED_BIT);
  
  	xfs_iunpin(ip);
  
  	do {
  		prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
  		if (xfs_ipincount(ip))
  			io_schedule();
  	} while (xfs_ipincount(ip));
  	finish_wait(wq, &wait.wait);
  }
  
  void
  xfs_iunpin_wait(
  	struct xfs_inode	*ip)
  {
  	if (xfs_ipincount(ip))
  		__xfs_iunpin_wait(ip);
  }
  
  /*
   * Removing an inode from the namespace involves removing the directory entry
   * and dropping the link count on the inode. Removing the directory entry can
   * result in locking an AGF (directory blocks were freed) and removing a link
   * count can result in placing the inode on an unlinked list which results in
   * locking an AGI.
   *
   * The big problem here is that we have an ordering constraint on AGF and AGI
   * locking - inode allocation locks the AGI, then can allocate a new extent for
   * new inodes, locking the AGF after the AGI. Similarly, freeing the inode
   * removes the inode from the unlinked list, requiring that we lock the AGI
   * first, and then freeing the inode can result in an inode chunk being freed
   * and hence freeing disk space requiring that we lock an AGF.
   *
   * Hence the ordering that is imposed by other parts of the code is AGI before
   * AGF. This means we cannot remove the directory entry before we drop the inode
   * reference count and put it on the unlinked list as this results in a lock
   * order of AGF then AGI, and this can deadlock against inode allocation and
   * freeing. Therefore we must drop the link counts before we remove the
   * directory entry.
   *
   * This is still safe from a transactional point of view - it is not until we
   * get to xfs_bmap_finish() that we have the possibility of multiple
   * transactions in this operation. Hence as long as we remove the directory
   * entry and drop the link count in the first transaction of the remove
   * operation, there are no transactional constraints on the ordering here.
   */
  int
  xfs_remove(
  	xfs_inode_t             *dp,
  	struct xfs_name		*name,
  	xfs_inode_t		*ip)
  {
  	xfs_mount_t		*mp = dp->i_mount;
  	xfs_trans_t             *tp = NULL;
  	int			is_dir = S_ISDIR(ip->i_d.di_mode);
  	int                     error = 0;
  	xfs_bmap_free_t         free_list;
  	xfs_fsblock_t           first_block;
  	int			cancel_flags;
  	int			committed;
  	int			link_zero;
  	uint			resblks;
  	uint			log_count;
  
  	trace_xfs_remove(dp, name);
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return XFS_ERROR(EIO);
  
  	error = xfs_qm_dqattach(dp, 0);
  	if (error)
  		goto std_return;
  
  	error = xfs_qm_dqattach(ip, 0);
  	if (error)
  		goto std_return;
  
  	if (is_dir) {
  		tp = xfs_trans_alloc(mp, XFS_TRANS_RMDIR);
  		log_count = XFS_DEFAULT_LOG_COUNT;
  	} else {
  		tp = xfs_trans_alloc(mp, XFS_TRANS_REMOVE);
  		log_count = XFS_REMOVE_LOG_COUNT;
  	}
  	cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
  
  	/*
  	 * We try to get the real space reservation first,
  	 * allowing for directory btree deletion(s) implying
  	 * possible bmap insert(s).  If we can't get the space
  	 * reservation then we use 0 instead, and avoid the bmap
  	 * btree insert(s) in the directory code by, if the bmap
  	 * insert tries to happen, instead trimming the LAST
  	 * block from the directory.
  	 */
  	resblks = XFS_REMOVE_SPACE_RES(mp);
  	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_remove, resblks, 0);
  	if (error == ENOSPC) {
  		resblks = 0;
  		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_remove, 0, 0);
  	}
  	if (error) {
  		ASSERT(error != ENOSPC);
  		cancel_flags = 0;
  		goto out_trans_cancel;
  	}
  
  	xfs_lock_two_inodes(dp, ip, XFS_ILOCK_EXCL);
  
  	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
  
  	/*
  	 * If we're removing a directory perform some additional validation.
  	 */
  	cancel_flags |= XFS_TRANS_ABORT;
  	if (is_dir) {
  		ASSERT(ip->i_d.di_nlink >= 2);
  		if (ip->i_d.di_nlink != 2) {
  			error = XFS_ERROR(ENOTEMPTY);
  			goto out_trans_cancel;
  		}
  		if (!xfs_dir_isempty(ip)) {
  			error = XFS_ERROR(ENOTEMPTY);
  			goto out_trans_cancel;
  		}
  
  		/* Drop the link from ip's "..".  */
  		error = xfs_droplink(tp, dp);
  		if (error)
  			goto out_trans_cancel;
  
  		/* Drop the "." link from ip to self.  */
  		error = xfs_droplink(tp, ip);
  		if (error)
  			goto out_trans_cancel;
  	} else {
  		/*
  		 * When removing a non-directory we need to log the parent
  		 * inode here.  For a directory this is done implicitly
  		 * by the xfs_droplink call for the ".." entry.
  		 */
  		xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
  	}
  	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  
  	/* Drop the link from dp to ip. */
  	error = xfs_droplink(tp, ip);
  	if (error)
  		goto out_trans_cancel;
  
  	/* Determine if this is the last link while the inode is locked */
  	link_zero = (ip->i_d.di_nlink == 0);
  
  	xfs_bmap_init(&free_list, &first_block);
  	error = xfs_dir_removename(tp, dp, name, ip->i_ino,
  					&first_block, &free_list, resblks);
  	if (error) {
  		ASSERT(error != ENOENT);
  		goto out_bmap_cancel;
  	}
  
  	/*
  	 * If this is a synchronous mount, make sure that the
  	 * remove transaction goes to disk before returning to
  	 * the user.
  	 */
  	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC))
  		xfs_trans_set_sync(tp);
  
  	error = xfs_bmap_finish(&tp, &free_list, &committed);
  	if (error)
  		goto out_bmap_cancel;
  
  	error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
  	if (error)
  		goto std_return;
  
  	/*
  	 * If we are using filestreams, kill the stream association.
  	 * If the file is still open it may get a new one but that
  	 * will get killed on last close in xfs_close() so we don't
  	 * have to worry about that.
  	 */
  	if (!is_dir && link_zero && xfs_inode_is_filestream(ip))
  		xfs_filestream_deassociate(ip);
  
  	return 0;
  
   out_bmap_cancel:
  	xfs_bmap_cancel(&free_list);
   out_trans_cancel:
  	xfs_trans_cancel(tp, cancel_flags);
   std_return:
  	return error;
  }
  
  /*
   * Enter all inodes for a rename transaction into a sorted array.
   */
  STATIC void
  xfs_sort_for_rename(
  	xfs_inode_t	*dp1,	/* in: old (source) directory inode */
  	xfs_inode_t	*dp2,	/* in: new (target) directory inode */
  	xfs_inode_t	*ip1,	/* in: inode of old entry */
  	xfs_inode_t	*ip2,	/* in: inode of new entry, if it
  				   already exists, NULL otherwise. */
  	xfs_inode_t	**i_tab,/* out: array of inode returned, sorted */
  	int		*num_inodes)  /* out: number of inodes in array */
  {
  	xfs_inode_t		*temp;
  	int			i, j;
  
  	/*
  	 * i_tab contains a list of pointers to inodes.  We initialize
  	 * the table here & we'll sort it.  We will then use it to
  	 * order the acquisition of the inode locks.
  	 *
  	 * Note that the table may contain duplicates.  e.g., dp1 == dp2.
  	 */
  	i_tab[0] = dp1;
  	i_tab[1] = dp2;
  	i_tab[2] = ip1;
  	if (ip2) {
  		*num_inodes = 4;
  		i_tab[3] = ip2;
  	} else {
  		*num_inodes = 3;
  		i_tab[3] = NULL;
  	}
  
  	/*
  	 * Sort the elements via bubble sort.  (Remember, there are at
  	 * most 4 elements to sort, so this is adequate.)
  	 */
  	for (i = 0; i < *num_inodes; i++) {
  		for (j = 1; j < *num_inodes; j++) {
  			if (i_tab[j]->i_ino < i_tab[j-1]->i_ino) {
  				temp = i_tab[j];
  				i_tab[j] = i_tab[j-1];
  				i_tab[j-1] = temp;
  			}
  		}
  	}
  }
  
  /*
   * xfs_rename
   */
  int
  xfs_rename(
  	xfs_inode_t	*src_dp,
  	struct xfs_name	*src_name,
  	xfs_inode_t	*src_ip,
  	xfs_inode_t	*target_dp,
  	struct xfs_name	*target_name,
  	xfs_inode_t	*target_ip)
  {
  	xfs_trans_t	*tp = NULL;
  	xfs_mount_t	*mp = src_dp->i_mount;
  	int		new_parent;		/* moving to a new dir */
  	int		src_is_directory;	/* src_name is a directory */
  	int		error;
  	xfs_bmap_free_t free_list;
  	xfs_fsblock_t   first_block;
  	int		cancel_flags;
  	int		committed;
  	xfs_inode_t	*inodes[4];
  	int		spaceres;
  	int		num_inodes;
  
  	trace_xfs_rename(src_dp, target_dp, src_name, target_name);
  
  	new_parent = (src_dp != target_dp);
  	src_is_directory = S_ISDIR(src_ip->i_d.di_mode);
  
  	xfs_sort_for_rename(src_dp, target_dp, src_ip, target_ip,
  				inodes, &num_inodes);
  
  	xfs_bmap_init(&free_list, &first_block);
  	tp = xfs_trans_alloc(mp, XFS_TRANS_RENAME);
  	cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
  	spaceres = XFS_RENAME_SPACE_RES(mp, target_name->len);
  	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_rename, spaceres, 0);
  	if (error == ENOSPC) {
  		spaceres = 0;
  		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_rename, 0, 0);
  	}
  	if (error) {
  		xfs_trans_cancel(tp, 0);
  		goto std_return;
  	}
  
  	/*
  	 * Attach the dquots to the inodes
  	 */
  	error = xfs_qm_vop_rename_dqattach(inodes);
  	if (error) {
  		xfs_trans_cancel(tp, cancel_flags);
  		goto std_return;
  	}
  
  	/*
  	 * Lock all the participating inodes. Depending upon whether
  	 * the target_name exists in the target directory, and
  	 * whether the target directory is the same as the source
  	 * directory, we can lock from 2 to 4 inodes.
  	 */
  	xfs_lock_inodes(inodes, num_inodes, XFS_ILOCK_EXCL);
  
  	/*
  	 * Join all the inodes to the transaction. From this point on,
  	 * we can rely on either trans_commit or trans_cancel to unlock
  	 * them.
  	 */
  	xfs_trans_ijoin(tp, src_dp, XFS_ILOCK_EXCL);
  	if (new_parent)
  		xfs_trans_ijoin(tp, target_dp, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, src_ip, XFS_ILOCK_EXCL);
  	if (target_ip)
  		xfs_trans_ijoin(tp, target_ip, XFS_ILOCK_EXCL);
  
  	/*
  	 * If we are using project inheritance, we only allow renames
  	 * into our tree when the project IDs are the same; else the
  	 * tree quota mechanism would be circumvented.
  	 */
  	if (unlikely((target_dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
  		     (xfs_get_projid(target_dp) != xfs_get_projid(src_ip)))) {
  		error = XFS_ERROR(EXDEV);
  		goto error_return;
  	}
  
  	/*
  	 * Set up the target.
  	 */
  	if (target_ip == NULL) {
  		/*
  		 * If there's no space reservation, check the entry will
  		 * fit before actually inserting it.
  		 */
  		error = xfs_dir_canenter(tp, target_dp, target_name, spaceres);
  		if (error)
  			goto error_return;
  		/*
  		 * If target does not exist and the rename crosses
  		 * directories, adjust the target directory link count
  		 * to account for the ".." reference from the new entry.
  		 */
  		error = xfs_dir_createname(tp, target_dp, target_name,
  						src_ip->i_ino, &first_block,
  						&free_list, spaceres);
  		if (error == ENOSPC)
  			goto error_return;
  		if (error)
  			goto abort_return;
  
  		xfs_trans_ichgtime(tp, target_dp,
  					XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  
  		if (new_parent && src_is_directory) {
  			error = xfs_bumplink(tp, target_dp);
  			if (error)
  				goto abort_return;
  		}
  	} else { /* target_ip != NULL */
  		/*
  		 * If target exists and it's a directory, check that both
  		 * target and source are directories and that target can be
  		 * destroyed, or that neither is a directory.
  		 */
  		if (S_ISDIR(target_ip->i_d.di_mode)) {
  			/*
  			 * Make sure target dir is empty.
  			 */
  			if (!(xfs_dir_isempty(target_ip)) ||
  			    (target_ip->i_d.di_nlink > 2)) {
  				error = XFS_ERROR(EEXIST);
  				goto error_return;
  			}
  		}
  
  		/*
  		 * Link the source inode under the target name.
  		 * If the source inode is a directory and we are moving
  		 * it across directories, its ".." entry will be
  		 * inconsistent until we replace that down below.
  		 *
  		 * In case there is already an entry with the same
  		 * name at the destination directory, remove it first.
  		 */
  		error = xfs_dir_replace(tp, target_dp, target_name,
  					src_ip->i_ino,
  					&first_block, &free_list, spaceres);
  		if (error)
  			goto abort_return;
  
  		xfs_trans_ichgtime(tp, target_dp,
  					XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  
  		/*
  		 * Decrement the link count on the target since the target
  		 * dir no longer points to it.
  		 */
  		error = xfs_droplink(tp, target_ip);
  		if (error)
  			goto abort_return;
  
  		if (src_is_directory) {
  			/*
  			 * Drop the link from the old "." entry.
  			 */
  			error = xfs_droplink(tp, target_ip);
  			if (error)
  				goto abort_return;
  		}
  	} /* target_ip != NULL */
  
  	/*
  	 * Remove the source.
  	 */
  	if (new_parent && src_is_directory) {
  		/*
  		 * Rewrite the ".." entry to point to the new
  		 * directory.
  		 */
  		error = xfs_dir_replace(tp, src_ip, &xfs_name_dotdot,
  					target_dp->i_ino,
  					&first_block, &free_list, spaceres);
  		ASSERT(error != EEXIST);
  		if (error)
  			goto abort_return;
  	}
  
  	/*
  	 * We always want to hit the ctime on the source inode.
  	 *
  	 * This isn't strictly required by the standards since the source
  	 * inode isn't really being changed, but old unix file systems did
  	 * it and some incremental backup programs won't work without it.
  	 */
  	xfs_trans_ichgtime(tp, src_ip, XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, src_ip, XFS_ILOG_CORE);
  
  	/*
  	 * Adjust the link count on src_dp.  This is necessary when
  	 * renaming a directory, either within one parent when
  	 * the target existed, or across two parent directories.
  	 */
  	if (src_is_directory && (new_parent || target_ip != NULL)) {
  
  		/*
  		 * Decrement link count on src_directory since the
  		 * entry that's moved no longer points to it.
  		 */
  		error = xfs_droplink(tp, src_dp);
  		if (error)
  			goto abort_return;
  	}
  
  	error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino,
  					&first_block, &free_list, spaceres);
  	if (error)
  		goto abort_return;
  
  	xfs_trans_ichgtime(tp, src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE);
  	if (new_parent)
  		xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);
  
  	/*
  	 * If this is a synchronous mount, make sure that the
  	 * rename transaction goes to disk before returning to
  	 * the user.
  	 */
  	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
  		xfs_trans_set_sync(tp);
  	}
  
  	error = xfs_bmap_finish(&tp, &free_list, &committed);
  	if (error) {
  		xfs_bmap_cancel(&free_list);
  		xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES |
  				 XFS_TRANS_ABORT));
  		goto std_return;
  	}
  
  	/*
  	 * trans_commit will unlock src_ip, target_ip & decrement
  	 * the vnode references.
  	 */
  	return xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
  
   abort_return:
  	cancel_flags |= XFS_TRANS_ABORT;
   error_return:
  	xfs_bmap_cancel(&free_list);
  	xfs_trans_cancel(tp, cancel_flags);
   std_return:
  	return error;
  }
  
  STATIC int
  xfs_iflush_cluster(
  	xfs_inode_t	*ip,
  	xfs_buf_t	*bp)
  {
  	xfs_mount_t		*mp = ip->i_mount;
  	struct xfs_perag	*pag;
  	unsigned long		first_index, mask;
  	unsigned long		inodes_per_cluster;
  	int			ilist_size;
  	xfs_inode_t		**ilist;
  	xfs_inode_t		*iq;
  	int			nr_found;
  	int			clcount = 0;
  	int			bufwasdelwri;
  	int			i;
  
  	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
  
  	inodes_per_cluster = mp->m_inode_cluster_size >> mp->m_sb.sb_inodelog;
  	ilist_size = inodes_per_cluster * sizeof(xfs_inode_t *);
  	ilist = kmem_alloc(ilist_size, KM_MAYFAIL|KM_NOFS);
  	if (!ilist)
  		goto out_put;
  
  	mask = ~(((mp->m_inode_cluster_size >> mp->m_sb.sb_inodelog)) - 1);
  	first_index = XFS_INO_TO_AGINO(mp, ip->i_ino) & mask;
  	rcu_read_lock();
  	/* really need a gang lookup range call here */
  	nr_found = radix_tree_gang_lookup(&pag->pag_ici_root, (void**)ilist,
  					first_index, inodes_per_cluster);
  	if (nr_found == 0)
  		goto out_free;
  
  	for (i = 0; i < nr_found; i++) {
  		iq = ilist[i];
  		if (iq == ip)
  			continue;
  
  		/*
  		 * because this is an RCU protected lookup, we could find a
  		 * recently freed or even reallocated inode during the lookup.
  		 * We need to check under the i_flags_lock for a valid inode
  		 * here. Skip it if it is not valid or the wrong inode.
  		 */
  		spin_lock(&ip->i_flags_lock);
  		if (!ip->i_ino ||
  		    (XFS_INO_TO_AGINO(mp, iq->i_ino) & mask) != first_index) {
  			spin_unlock(&ip->i_flags_lock);
  			continue;
  		}
  		spin_unlock(&ip->i_flags_lock);
  
  		/*
  		 * Do an un-protected check to see if the inode is dirty and
  		 * is a candidate for flushing.  These checks will be repeated
  		 * later after the appropriate locks are acquired.
  		 */
  		if (xfs_inode_clean(iq) && xfs_ipincount(iq) == 0)
  			continue;
  
  		/*
  		 * Try to get locks.  If any are unavailable or it is pinned,
  		 * then this inode cannot be flushed and is skipped.
  		 */
  
  		if (!xfs_ilock_nowait(iq, XFS_ILOCK_SHARED))
  			continue;
  		if (!xfs_iflock_nowait(iq)) {
  			xfs_iunlock(iq, XFS_ILOCK_SHARED);
  			continue;
  		}
  		if (xfs_ipincount(iq)) {
  			xfs_ifunlock(iq);
  			xfs_iunlock(iq, XFS_ILOCK_SHARED);
  			continue;
  		}
  
  		/*
  		 * arriving here means that this inode can be flushed.  First
  		 * re-check that it's dirty before flushing.
  		 */
  		if (!xfs_inode_clean(iq)) {
  			int	error;
  			error = xfs_iflush_int(iq, bp);
  			if (error) {
  				xfs_iunlock(iq, XFS_ILOCK_SHARED);
  				goto cluster_corrupt_out;
  			}
  			clcount++;
  		} else {
  			xfs_ifunlock(iq);
  		}
  		xfs_iunlock(iq, XFS_ILOCK_SHARED);
  	}
  
  	if (clcount) {
  		XFS_STATS_INC(xs_icluster_flushcnt);
  		XFS_STATS_ADD(xs_icluster_flushinode, clcount);
  	}
  
  out_free:
  	rcu_read_unlock();
  	kmem_free(ilist);
  out_put:
  	xfs_perag_put(pag);
  	return 0;
  
  
  cluster_corrupt_out:
  	/*
  	 * Corruption detected in the clustering loop.  Invalidate the
  	 * inode buffer and shut down the filesystem.
  	 */
  	rcu_read_unlock();
  	/*
  	 * Clean up the buffer.  If it was delwri, just release it --
  	 * brelse can handle it with no problems.  If not, shut down the
  	 * filesystem before releasing the buffer.
  	 */
  	bufwasdelwri = (bp->b_flags & _XBF_DELWRI_Q);
  	if (bufwasdelwri)
  		xfs_buf_relse(bp);
  
  	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
  
  	if (!bufwasdelwri) {
  		/*
  		 * Just like incore_relse: if we have b_iodone functions,
  		 * mark the buffer as an error and call them.  Otherwise
  		 * mark it as stale and brelse.
  		 */
  		if (bp->b_iodone) {
  			XFS_BUF_UNDONE(bp);
  			xfs_buf_stale(bp);
  			xfs_buf_ioerror(bp, EIO);
  			xfs_buf_ioend(bp, 0);
  		} else {
  			xfs_buf_stale(bp);
  			xfs_buf_relse(bp);
  		}
  	}
  
  	/*
  	 * Unlocks the flush lock
  	 */
  	xfs_iflush_abort(iq, false);
  	kmem_free(ilist);
  	xfs_perag_put(pag);
  	return XFS_ERROR(EFSCORRUPTED);
  }
  
  /*
   * Flush dirty inode metadata into the backing buffer.
   *
   * The caller must have the inode lock and the inode flush lock held.  The
   * inode lock will still be held upon return to the caller, and the inode
   * flush lock will be released after the inode has reached the disk.
   *
   * The caller must write out the buffer returned in *bpp and release it.
   */
  int
  xfs_iflush(
  	struct xfs_inode	*ip,
  	struct xfs_buf		**bpp)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_buf		*bp;
  	struct xfs_dinode	*dip;
  	int			error;
  
  	XFS_STATS_INC(xs_iflush_count);
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
  	ASSERT(xfs_isiflocked(ip));
  	ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
  	       ip->i_d.di_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
  
  	*bpp = NULL;
  
  	xfs_iunpin_wait(ip);
  
  	/*
  	 * For stale inodes we cannot rely on the backing buffer remaining
  	 * stale in cache for the remaining life of the stale inode and so
  	 * xfs_imap_to_bp() below may give us a buffer that no longer contains
  	 * inodes below. We have to check this after ensuring the inode is
  	 * unpinned so that it is safe to reclaim the stale inode after the
  	 * flush call.
  	 */
  	if (xfs_iflags_test(ip, XFS_ISTALE)) {
  		xfs_ifunlock(ip);
  		return 0;
  	}
  
  	/*
  	 * This may have been unpinned because the filesystem is shutting
  	 * down forcibly. If that's the case we must not write this inode
  	 * to disk, because the log record didn't make it to disk.
  	 *
  	 * We also have to remove the log item from the AIL in this case,
  	 * as we wait for an empty AIL as part of the unmount process.
  	 */
  	if (XFS_FORCED_SHUTDOWN(mp)) {
  		error = XFS_ERROR(EIO);
  		goto abort_out;
  	}
  
  	/*
  	 * Get the buffer containing the on-disk inode.
  	 */
  	error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &bp, XBF_TRYLOCK,
  			       0);
  	if (error || !bp) {
  		xfs_ifunlock(ip);
  		return error;
  	}
  
  	/*
  	 * First flush out the inode that xfs_iflush was called with.
  	 */
  	error = xfs_iflush_int(ip, bp);
  	if (error)
  		goto corrupt_out;
  
  	/*
  	 * If the buffer is pinned then push on the log now so we won't
  	 * get stuck waiting in the write for too long.
  	 */
  	if (xfs_buf_ispinned(bp))
  		xfs_log_force(mp, 0);
  
  	/*
  	 * inode clustering:
  	 * see if other inodes can be gathered into this write
  	 */
  	error = xfs_iflush_cluster(ip, bp);
  	if (error)
  		goto cluster_corrupt_out;
  
  	*bpp = bp;
  	return 0;
  
  corrupt_out:
  	xfs_buf_relse(bp);
  	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
  cluster_corrupt_out:
  	error = XFS_ERROR(EFSCORRUPTED);
  abort_out:
  	/*
  	 * Unlocks the flush lock
  	 */
  	xfs_iflush_abort(ip, false);
  	return error;
  }
  
  STATIC int
  xfs_iflush_int(
  	struct xfs_inode	*ip,
  	struct xfs_buf		*bp)
  {
  	struct xfs_inode_log_item *iip = ip->i_itemp;
  	struct xfs_dinode	*dip;
  	struct xfs_mount	*mp = ip->i_mount;
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
  	ASSERT(xfs_isiflocked(ip));
  	ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
  	       ip->i_d.di_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
  	ASSERT(iip != NULL && iip->ili_fields != 0);
  
  	/* set *dip = inode's place in the buffer */
  	dip = (xfs_dinode_t *)xfs_buf_offset(bp, ip->i_imap.im_boffset);
  
  	if (XFS_TEST_ERROR(dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC),
  			       mp, XFS_ERRTAG_IFLUSH_1, XFS_RANDOM_IFLUSH_1)) {
  		xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  			"%s: Bad inode %Lu magic number 0x%x, ptr 0x%p",
  			__func__, ip->i_ino, be16_to_cpu(dip->di_magic), dip);
  		goto corrupt_out;
  	}
  	if (XFS_TEST_ERROR(ip->i_d.di_magic != XFS_DINODE_MAGIC,
  				mp, XFS_ERRTAG_IFLUSH_2, XFS_RANDOM_IFLUSH_2)) {
  		xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  			"%s: Bad inode %Lu, ptr 0x%p, magic number 0x%x",
  			__func__, ip->i_ino, ip, ip->i_d.di_magic);
  		goto corrupt_out;
  	}
  	if (S_ISREG(ip->i_d.di_mode)) {
  		if (XFS_TEST_ERROR(
  		    (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
  		    (ip->i_d.di_format != XFS_DINODE_FMT_BTREE),
  		    mp, XFS_ERRTAG_IFLUSH_3, XFS_RANDOM_IFLUSH_3)) {
  			xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  				"%s: Bad regular inode %Lu, ptr 0x%p",
  				__func__, ip->i_ino, ip);
  			goto corrupt_out;
  		}
  	} else if (S_ISDIR(ip->i_d.di_mode)) {
  		if (XFS_TEST_ERROR(
  		    (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
  		    (ip->i_d.di_format != XFS_DINODE_FMT_BTREE) &&
  		    (ip->i_d.di_format != XFS_DINODE_FMT_LOCAL),
  		    mp, XFS_ERRTAG_IFLUSH_4, XFS_RANDOM_IFLUSH_4)) {
  			xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  				"%s: Bad directory inode %Lu, ptr 0x%p",
  				__func__, ip->i_ino, ip);
  			goto corrupt_out;
  		}
  	}
  	if (XFS_TEST_ERROR(ip->i_d.di_nextents + ip->i_d.di_anextents >
  				ip->i_d.di_nblocks, mp, XFS_ERRTAG_IFLUSH_5,
  				XFS_RANDOM_IFLUSH_5)) {
  		xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  			"%s: detected corrupt incore inode %Lu, "
  			"total extents = %d, nblocks = %Ld, ptr 0x%p",
  			__func__, ip->i_ino,
  			ip->i_d.di_nextents + ip->i_d.di_anextents,
  			ip->i_d.di_nblocks, ip);
  		goto corrupt_out;
  	}
  	if (XFS_TEST_ERROR(ip->i_d.di_forkoff > mp->m_sb.sb_inodesize,
  				mp, XFS_ERRTAG_IFLUSH_6, XFS_RANDOM_IFLUSH_6)) {
  		xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  			"%s: bad inode %Lu, forkoff 0x%x, ptr 0x%p",
  			__func__, ip->i_ino, ip->i_d.di_forkoff, ip);
  		goto corrupt_out;
  	}
  
  	/*
  	 * Inode item log recovery for v1/v2 inodes are dependent on the
  	 * di_flushiter count for correct sequencing. We bump the flush
  	 * iteration count so we can detect flushes which postdate a log record
  	 * during recovery. This is redundant as we now log every change and
  	 * hence this can't happen but we need to still do it to ensure
  	 * backwards compatibility with old kernels that predate logging all
  	 * inode changes.
  	 */
  	if (ip->i_d.di_version < 3)
  		ip->i_d.di_flushiter++;
  
  	/*
  	 * Copy the dirty parts of the inode into the on-disk
  	 * inode.  We always copy out the core of the inode,
  	 * because if the inode is dirty at all the core must
  	 * be.
  	 */
  	xfs_dinode_to_disk(dip, &ip->i_d);
  
  	/* Wrap, we never let the log put out DI_MAX_FLUSH */
  	if (ip->i_d.di_flushiter == DI_MAX_FLUSH)
  		ip->i_d.di_flushiter = 0;
  
  	/*
  	 * If this is really an old format inode and the superblock version
  	 * has not been updated to support only new format inodes, then
  	 * convert back to the old inode format.  If the superblock version
  	 * has been updated, then make the conversion permanent.
  	 */
  	ASSERT(ip->i_d.di_version == 1 || xfs_sb_version_hasnlink(&mp->m_sb));
  	if (ip->i_d.di_version == 1) {
  		if (!xfs_sb_version_hasnlink(&mp->m_sb)) {
  			/*
  			 * Convert it back.
  			 */
  			ASSERT(ip->i_d.di_nlink <= XFS_MAXLINK_1);
  			dip->di_onlink = cpu_to_be16(ip->i_d.di_nlink);
  		} else {
  			/*
  			 * The superblock version has already been bumped,
  			 * so just make the conversion to the new inode
  			 * format permanent.
  			 */
  			ip->i_d.di_version = 2;
  			dip->di_version = 2;
  			ip->i_d.di_onlink = 0;
  			dip->di_onlink = 0;
  			memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
  			memset(&(dip->di_pad[0]), 0,
  			      sizeof(dip->di_pad));
  			ASSERT(xfs_get_projid(ip) == 0);
  		}
  	}
  
  	xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK, bp);
  	if (XFS_IFORK_Q(ip))
  		xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK, bp);
  	xfs_inobp_check(mp, bp);
  
  	/*
  	 * We've recorded everything logged in the inode, so we'd like to clear
  	 * the ili_fields bits so we don't log and flush things unnecessarily.
  	 * However, we can't stop logging all this information until the data
  	 * we've copied into the disk buffer is written to disk.  If we did we
  	 * might overwrite the copy of the inode in the log with all the data
  	 * after re-logging only part of it, and in the face of a crash we
  	 * wouldn't have all the data we need to recover.
  	 *
  	 * What we do is move the bits to the ili_last_fields field.  When
  	 * logging the inode, these bits are moved back to the ili_fields field.
  	 * In the xfs_iflush_done() routine we clear ili_last_fields, since we
  	 * know that the information those bits represent is permanently on
  	 * disk.  As long as the flush completes before the inode is logged
  	 * again, then both ili_fields and ili_last_fields will be cleared.
  	 *
  	 * We can play with the ili_fields bits here, because the inode lock
  	 * must be held exclusively in order to set bits there and the flush
  	 * lock protects the ili_last_fields bits.  Set ili_logged so the flush
  	 * done routine can tell whether or not to look in the AIL.  Also, store
  	 * the current LSN of the inode so that we can tell whether the item has
  	 * moved in the AIL from xfs_iflush_done().  In order to read the lsn we
  	 * need the AIL lock, because it is a 64 bit value that cannot be read
  	 * atomically.
  	 */
  	iip->ili_last_fields = iip->ili_fields;
  	iip->ili_fields = 0;
  	iip->ili_logged = 1;
  
  	xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
  				&iip->ili_item.li_lsn);
  
  	/*
  	 * Attach the function xfs_iflush_done to the inode's
  	 * buffer.  This will remove the inode from the AIL
  	 * and unlock the inode's flush lock when the inode is
  	 * completely written to disk.
  	 */
  	xfs_buf_attach_iodone(bp, xfs_iflush_done, &iip->ili_item);
  
  	/* update the lsn in the on disk inode if required */
  	if (ip->i_d.di_version == 3)
  		dip->di_lsn = cpu_to_be64(iip->ili_item.li_lsn);
  
  	/* generate the checksum. */
  	xfs_dinode_calc_crc(mp, dip);
  
  	ASSERT(bp->b_fspriv != NULL);
  	ASSERT(bp->b_iodone != NULL);
  	return 0;
  
  corrupt_out:
  	return XFS_ERROR(EFSCORRUPTED);
  }