/*

   * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
   * All Rights Reserved.

   *

   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as

   * published by the Free Software Foundation.
   *

   * This program is distributed in the hope that it would be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.

   *

   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write the Free Software Foundation,
   * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

   */

  #include "xfs.h"

  #include "xfs_fs.h"

  #include "xfs_types.h"

  #include "xfs_bit.h"

  #include "xfs_log.h"

  #include "xfs_inum.h"

  #include "xfs_trans.h"
  #include "xfs_sb.h"
  #include "xfs_ag.h"

  #include "xfs_mount.h"

  #include "xfs_bmap_btree.h"

  #include "xfs_alloc_btree.h"

  #include "xfs_ialloc_btree.h"

  #include "xfs_dinode.h"
  #include "xfs_inode.h"

  #include "xfs_btree.h"
  #include "xfs_ialloc.h"

  #include "xfs_alloc.h"

  #include "xfs_rtalloc.h"
  #include "xfs_error.h"
  #include "xfs_bmap.h"

  
  /*
   * Allocation group level functions.
   */

  static inline int
  xfs_ialloc_cluster_alignment(
  	xfs_alloc_arg_t	*args)
  {
  	if (xfs_sb_version_hasalign(&args->mp->m_sb) &&
  	    args->mp->m_sb.sb_inoalignmt >=
  	     XFS_B_TO_FSBT(args->mp, XFS_INODE_CLUSTER_SIZE(args->mp)))
  		return args->mp->m_sb.sb_inoalignmt;
  	return 1;
  }

  
  /*

   * Lookup a record by ino in the btree given by cur.

   */

  int					/* error */

  xfs_inobt_lookup(

  	struct xfs_btree_cur	*cur,	/* btree cursor */
  	xfs_agino_t		ino,	/* starting inode of chunk */

  	xfs_lookup_t		dir,	/* <=, >=, == */

  	int			*stat)	/* success/failure */
  {
  	cur->bc_rec.i.ir_startino = ino;

  	cur->bc_rec.i.ir_freecount = 0;
  	cur->bc_rec.i.ir_free = 0;
  	return xfs_btree_lookup(cur, dir, stat);

  }
  
  /*

   * Update the record referred to by cur to the value given.

   * This either works (return 0) or gets an EFSCORRUPTED error.
   */
  STATIC int				/* error */
  xfs_inobt_update(
  	struct xfs_btree_cur	*cur,	/* btree cursor */

  	xfs_inobt_rec_incore_t	*irec)	/* btree record */

  {
  	union xfs_btree_rec	rec;

  	rec.inobt.ir_startino = cpu_to_be32(irec->ir_startino);
  	rec.inobt.ir_freecount = cpu_to_be32(irec->ir_freecount);
  	rec.inobt.ir_free = cpu_to_be64(irec->ir_free);

  	return xfs_btree_update(cur, &rec);
  }
  
  /*

   * Get the data from the pointed-to record.
   */
  int					/* error */
  xfs_inobt_get_rec(
  	struct xfs_btree_cur	*cur,	/* btree cursor */

  	xfs_inobt_rec_incore_t	*irec,	/* btree record */

  	int			*stat)	/* output: success/failure */
  {
  	union xfs_btree_rec	*rec;
  	int			error;
  
  	error = xfs_btree_get_rec(cur, &rec, stat);
  	if (!error && *stat == 1) {

  		irec->ir_startino = be32_to_cpu(rec->inobt.ir_startino);
  		irec->ir_freecount = be32_to_cpu(rec->inobt.ir_freecount);
  		irec->ir_free = be64_to_cpu(rec->inobt.ir_free);

  	}
  	return error;
  }
  
  /*

   * Verify that the number of free inodes in the AGI is correct.
   */
  #ifdef DEBUG
  STATIC int
  xfs_check_agi_freecount(
  	struct xfs_btree_cur	*cur,
  	struct xfs_agi		*agi)
  {
  	if (cur->bc_nlevels == 1) {
  		xfs_inobt_rec_incore_t rec;
  		int		freecount = 0;
  		int		error;
  		int		i;

  		error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &i);

  		if (error)
  			return error;
  
  		do {
  			error = xfs_inobt_get_rec(cur, &rec, &i);
  			if (error)
  				return error;
  
  			if (i) {
  				freecount += rec.ir_freecount;
  				error = xfs_btree_increment(cur, 0, &i);
  				if (error)
  					return error;
  			}
  		} while (i == 1);
  
  		if (!XFS_FORCED_SHUTDOWN(cur->bc_mp))
  			ASSERT(freecount == be32_to_cpu(agi->agi_freecount));
  	}
  	return 0;
  }
  #else
  #define xfs_check_agi_freecount(cur, agi)	0
  #endif
  
  /*

   * Initialise a new set of inodes.
   */

  STATIC int

  xfs_ialloc_inode_init(
  	struct xfs_mount	*mp,
  	struct xfs_trans	*tp,
  	xfs_agnumber_t		agno,
  	xfs_agblock_t		agbno,
  	xfs_agblock_t		length,
  	unsigned int		gen)
  {
  	struct xfs_buf		*fbuf;
  	struct xfs_dinode	*free;
  	int			blks_per_cluster, nbufs, ninodes;
  	int			version;
  	int			i, j;
  	xfs_daddr_t		d;
  
  	/*
  	 * Loop over the new block(s), filling in the inodes.
  	 * For small block sizes, manipulate the inodes in buffers
  	 * which are multiples of the blocks size.
  	 */
  	if (mp->m_sb.sb_blocksize >= XFS_INODE_CLUSTER_SIZE(mp)) {
  		blks_per_cluster = 1;
  		nbufs = length;
  		ninodes = mp->m_sb.sb_inopblock;
  	} else {
  		blks_per_cluster = XFS_INODE_CLUSTER_SIZE(mp) /
  				   mp->m_sb.sb_blocksize;
  		nbufs = length / blks_per_cluster;
  		ninodes = blks_per_cluster * mp->m_sb.sb_inopblock;
  	}
  
  	/*
  	 * Figure out what version number to use in the inodes we create.
  	 * If the superblock version has caught up to the one that supports
  	 * the new inode format, then use the new inode version.  Otherwise
  	 * use the old version so that old kernels will continue to be
  	 * able to use the file system.
  	 */
  	if (xfs_sb_version_hasnlink(&mp->m_sb))
  		version = 2;
  	else
  		version = 1;
  
  	for (j = 0; j < nbufs; j++) {
  		/*
  		 * Get the block.
  		 */
  		d = XFS_AGB_TO_DADDR(mp, agno, agbno + (j * blks_per_cluster));
  		fbuf = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
  					 mp->m_bsize * blks_per_cluster,

  					 XBF_LOCK);

  		if (!fbuf)
  			return ENOMEM;

  		/*
  		 * Initialize all inodes in this buffer and then log them.
  		 *
  		 * XXX: It would be much better if we had just one transaction
  		 *	to log a whole cluster of inodes instead of all the
  		 *	individual transactions causing a lot of log traffic.
  		 */

  		xfs_buf_zero(fbuf, 0, ninodes << mp->m_sb.sb_inodelog);

  		for (i = 0; i < ninodes; i++) {
  			int	ioffset = i << mp->m_sb.sb_inodelog;
  			uint	isize = sizeof(struct xfs_dinode);
  
  			free = xfs_make_iptr(mp, fbuf, i);
  			free->di_magic = cpu_to_be16(XFS_DINODE_MAGIC);
  			free->di_version = version;
  			free->di_gen = cpu_to_be32(gen);
  			free->di_next_unlinked = cpu_to_be32(NULLAGINO);
  			xfs_trans_log_buf(tp, fbuf, ioffset, ioffset + isize - 1);
  		}
  		xfs_trans_inode_alloc_buf(tp, fbuf);
  	}

  	return 0;

  }
  
  /*

   * Allocate new inodes in the allocation group specified by agbp.
   * Return 0 for success, else error code.
   */
  STATIC int				/* error code or 0 */
  xfs_ialloc_ag_alloc(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_buf_t	*agbp,		/* alloc group buffer */
  	int		*alloc)
  {
  	xfs_agi_t	*agi;		/* allocation group header */
  	xfs_alloc_arg_t	args;		/* allocation argument structure */

  	xfs_btree_cur_t	*cur;		/* inode btree cursor */

  	xfs_agnumber_t	agno;

  	int		error;

  	int		i;

  	xfs_agino_t	newino;		/* new first inode's number */
  	xfs_agino_t	newlen;		/* new number of inodes */

  	xfs_agino_t	thisino;	/* current inode number, for loop */

  	int		isaligned = 0;	/* inode allocation at stripe unit */

  					/* boundary */

  	struct xfs_perag *pag;

  
  	args.tp = tp;
  	args.mp = tp->t_mountp;
  
  	/*
  	 * Locking will ensure that we don't have two callers in here
  	 * at one time.
  	 */
  	newlen = XFS_IALLOC_INODES(args.mp);
  	if (args.mp->m_maxicount &&
  	    args.mp->m_sb.sb_icount + newlen > args.mp->m_maxicount)
  		return XFS_ERROR(ENOSPC);
  	args.minlen = args.maxlen = XFS_IALLOC_BLOCKS(args.mp);
  	/*

  	 * First try to allocate inodes contiguous with the last-allocated
  	 * chunk of inodes.  If the filesystem is striped, this will fill
  	 * an entire stripe unit with inodes.
   	 */

  	agi = XFS_BUF_TO_AGI(agbp);

  	newino = be32_to_cpu(agi->agi_newino);

  	agno = be32_to_cpu(agi->agi_seqno);

  	args.agbno = XFS_AGINO_TO_AGBNO(args.mp, newino) +
  			XFS_IALLOC_BLOCKS(args.mp);
  	if (likely(newino != NULLAGINO &&
  		  (args.agbno < be32_to_cpu(agi->agi_length)))) {

  		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);

  		args.type = XFS_ALLOCTYPE_THIS_BNO;
  		args.mod = args.total = args.wasdel = args.isfl =
  			args.userdata = args.minalignslop = 0;
  		args.prod = 1;

  		/*

  		 * We need to take into account alignment here to ensure that
  		 * we don't modify the free list if we fail to have an exact
  		 * block. If we don't have an exact match, and every oher
  		 * attempt allocation attempt fails, we'll end up cancelling
  		 * a dirty transaction and shutting down.
  		 *
  		 * For an exact allocation, alignment must be 1,
  		 * however we need to take cluster alignment into account when
  		 * fixing up the freelist. Use the minalignslop field to
  		 * indicate that extra blocks might be required for alignment,
  		 * but not to use them in the actual exact allocation.

  		 */

  		args.alignment = 1;
  		args.minalignslop = xfs_ialloc_cluster_alignment(&args) - 1;
  
  		/* Allow space for the inode btree to split. */

  		args.minleft = args.mp->m_in_maxlevels - 1;

  		if ((error = xfs_alloc_vextent(&args)))
  			return error;
  	} else
  		args.fsbno = NULLFSBLOCK;

  	if (unlikely(args.fsbno == NULLFSBLOCK)) {
  		/*
  		 * Set the alignment for the allocation.
  		 * If stripe alignment is turned on then align at stripe unit
  		 * boundary.

  		 * If the cluster size is smaller than a filesystem block
  		 * then we're doing I/O for inodes in filesystem block size

  		 * pieces, so don't need alignment anyway.
  		 */
  		isaligned = 0;
  		if (args.mp->m_sinoalign) {
  			ASSERT(!(args.mp->m_flags & XFS_MOUNT_NOALIGN));
  			args.alignment = args.mp->m_dalign;
  			isaligned = 1;

  		} else
  			args.alignment = xfs_ialloc_cluster_alignment(&args);

  		/*
  		 * Need to figure out where to allocate the inode blocks.
  		 * Ideally they should be spaced out through the a.g.
  		 * For now, just allocate blocks up front.
  		 */
  		args.agbno = be32_to_cpu(agi->agi_root);

  		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);

  		/*
  		 * Allocate a fixed-size extent of inodes.
  		 */
  		args.type = XFS_ALLOCTYPE_NEAR_BNO;
  		args.mod = args.total = args.wasdel = args.isfl =
  			args.userdata = args.minalignslop = 0;
  		args.prod = 1;
  		/*
  		 * Allow space for the inode btree to split.
  		 */

  		args.minleft = args.mp->m_in_maxlevels - 1;

  		if ((error = xfs_alloc_vextent(&args)))
  			return error;
  	}

  	/*
  	 * If stripe alignment is turned on, then try again with cluster
  	 * alignment.
  	 */
  	if (isaligned && args.fsbno == NULLFSBLOCK) {
  		args.type = XFS_ALLOCTYPE_NEAR_BNO;

  		args.agbno = be32_to_cpu(agi->agi_root);

  		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);

  		args.alignment = xfs_ialloc_cluster_alignment(&args);

  		if ((error = xfs_alloc_vextent(&args)))
  			return error;
  	}
  
  	if (args.fsbno == NULLFSBLOCK) {
  		*alloc = 0;
  		return 0;
  	}
  	ASSERT(args.len == args.minlen);

  	/*

  	 * Stamp and write the inode buffers.
  	 *

  	 * Seed the new inode cluster with a random generation number. This
  	 * prevents short-term reuse of generation numbers if a chunk is
  	 * freed and then immediately reallocated. We use random numbers
  	 * rather than a linear progression to prevent the next generation
  	 * number from being easily guessable.
  	 */

  	error = xfs_ialloc_inode_init(args.mp, tp, agno, args.agbno,
  			args.len, random32());

  	if (error)
  		return error;

  	/*
  	 * Convert the results.
  	 */
  	newino = XFS_OFFBNO_TO_AGINO(args.mp, args.agbno, 0);

  	be32_add_cpu(&agi->agi_count, newlen);
  	be32_add_cpu(&agi->agi_freecount, newlen);

  	pag = xfs_perag_get(args.mp, agno);
  	pag->pagi_freecount += newlen;
  	xfs_perag_put(pag);

  	agi->agi_newino = cpu_to_be32(newino);

  	/*
  	 * Insert records describing the new inode chunk into the btree.
  	 */

  	cur = xfs_inobt_init_cursor(args.mp, tp, agbp, agno);

  	for (thisino = newino;
  	     thisino < newino + newlen;
  	     thisino += XFS_INODES_PER_CHUNK) {

  		cur->bc_rec.i.ir_startino = thisino;
  		cur->bc_rec.i.ir_freecount = XFS_INODES_PER_CHUNK;
  		cur->bc_rec.i.ir_free = XFS_INOBT_ALL_FREE;
  		error = xfs_btree_lookup(cur, XFS_LOOKUP_EQ, &i);
  		if (error) {

  			xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  			return error;
  		}
  		ASSERT(i == 0);

  		error = xfs_btree_insert(cur, &i);
  		if (error) {

  			xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  			return error;
  		}
  		ASSERT(i == 1);
  	}
  	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  	/*
  	 * Log allocation group header fields
  	 */
  	xfs_ialloc_log_agi(tp, agbp,
  		XFS_AGI_COUNT | XFS_AGI_FREECOUNT | XFS_AGI_NEWINO);
  	/*
  	 * Modify/log superblock values for inode count and inode free count.
  	 */
  	xfs_trans_mod_sb(tp, XFS_TRANS_SB_ICOUNT, (long)newlen);
  	xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, (long)newlen);
  	*alloc = 1;
  	return 0;
  }

  STATIC xfs_agnumber_t

  xfs_ialloc_next_ag(
  	xfs_mount_t	*mp)
  {
  	xfs_agnumber_t	agno;
  
  	spin_lock(&mp->m_agirotor_lock);
  	agno = mp->m_agirotor;
  	if (++mp->m_agirotor == mp->m_maxagi)
  		mp->m_agirotor = 0;
  	spin_unlock(&mp->m_agirotor_lock);
  
  	return agno;
  }
  
  /*
   * Select an allocation group to look for a free inode in, based on the parent
   * inode and then mode.  Return the allocation group buffer.
   */
  STATIC xfs_buf_t *			/* allocation group buffer */
  xfs_ialloc_ag_select(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_ino_t	parent,		/* parent directory inode number */

  	umode_t		mode,		/* bits set to indicate file type */

  	int		okalloc)	/* ok to allocate more space */
  {
  	xfs_buf_t	*agbp;		/* allocation group header buffer */
  	xfs_agnumber_t	agcount;	/* number of ag's in the filesystem */
  	xfs_agnumber_t	agno;		/* current ag number */
  	int		flags;		/* alloc buffer locking flags */
  	xfs_extlen_t	ineed;		/* blocks needed for inode allocation */
  	xfs_extlen_t	longest = 0;	/* longest extent available */
  	xfs_mount_t	*mp;		/* mount point structure */
  	int		needspace;	/* file mode implies space allocated */
  	xfs_perag_t	*pag;		/* per allocation group data */
  	xfs_agnumber_t	pagno;		/* parent (starting) ag number */
  
  	/*
  	 * Files of these types need at least one block if length > 0
  	 * (and they won't fit in the inode, but that's hard to figure out).
  	 */
  	needspace = S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode);
  	mp = tp->t_mountp;
  	agcount = mp->m_maxagi;
  	if (S_ISDIR(mode))
  		pagno = xfs_ialloc_next_ag(mp);
  	else {
  		pagno = XFS_INO_TO_AGNO(mp, parent);
  		if (pagno >= agcount)
  			pagno = 0;
  	}
  	ASSERT(pagno < agcount);
  	/*
  	 * Loop through allocation groups, looking for one with a little
  	 * free space in it.  Note we don't look for free inodes, exactly.
  	 * Instead, we include whether there is a need to allocate inodes
  	 * to mean that blocks must be allocated for them,
  	 * if none are currently free.
  	 */
  	agno = pagno;
  	flags = XFS_ALLOC_FLAG_TRYLOCK;

  	for (;;) {

  		pag = xfs_perag_get(mp, agno);

  		if (!pag->pagi_init) {
  			if (xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
  				agbp = NULL;
  				goto nextag;
  			}
  		} else
  			agbp = NULL;
  
  		if (!pag->pagi_inodeok) {
  			xfs_ialloc_next_ag(mp);
  			goto unlock_nextag;
  		}
  
  		/*
  		 * Is there enough free space for the file plus a block
  		 * of inodes (if we need to allocate some)?
  		 */
  		ineed = pag->pagi_freecount ? 0 : XFS_IALLOC_BLOCKS(mp);
  		if (ineed && !pag->pagf_init) {
  			if (agbp == NULL &&
  			    xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
  				agbp = NULL;
  				goto nextag;
  			}
  			(void)xfs_alloc_pagf_init(mp, tp, agno, flags);
  		}
  		if (!ineed || pag->pagf_init) {
  			if (ineed && !(longest = pag->pagf_longest))
  				longest = pag->pagf_flcount > 0;
  			if (!ineed ||
  			    (pag->pagf_freeblks >= needspace + ineed &&
  			     longest >= ineed &&
  			     okalloc)) {
  				if (agbp == NULL &&
  				    xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
  					agbp = NULL;
  					goto nextag;
  				}

  				xfs_perag_put(pag);

  				return agbp;
  			}
  		}
  unlock_nextag:
  		if (agbp)
  			xfs_trans_brelse(tp, agbp);
  nextag:

  		xfs_perag_put(pag);

  		/*
  		 * No point in iterating over the rest, if we're shutting
  		 * down.
  		 */

  		if (XFS_FORCED_SHUTDOWN(mp))

  			return NULL;

  		agno++;
  		if (agno >= agcount)
  			agno = 0;
  		if (agno == pagno) {

  			if (flags == 0)

  				return NULL;

  			flags = 0;
  		}
  	}
  }

  /*
   * Try to retrieve the next record to the left/right from the current one.
   */
  STATIC int
  xfs_ialloc_next_rec(
  	struct xfs_btree_cur	*cur,
  	xfs_inobt_rec_incore_t	*rec,
  	int			*done,
  	int			left)
  {
  	int                     error;
  	int			i;
  
  	if (left)
  		error = xfs_btree_decrement(cur, 0, &i);
  	else
  		error = xfs_btree_increment(cur, 0, &i);
  
  	if (error)
  		return error;
  	*done = !i;
  	if (i) {
  		error = xfs_inobt_get_rec(cur, rec, &i);
  		if (error)
  			return error;
  		XFS_WANT_CORRUPTED_RETURN(i == 1);
  	}
  
  	return 0;
  }

  STATIC int
  xfs_ialloc_get_rec(
  	struct xfs_btree_cur	*cur,
  	xfs_agino_t		agino,
  	xfs_inobt_rec_incore_t	*rec,
  	int			*done,
  	int			left)
  {
  	int                     error;
  	int			i;
  
  	error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_EQ, &i);
  	if (error)
  		return error;
  	*done = !i;
  	if (i) {
  		error = xfs_inobt_get_rec(cur, rec, &i);
  		if (error)
  			return error;
  		XFS_WANT_CORRUPTED_RETURN(i == 1);
  	}
  
  	return 0;
  }

  /*
   * Visible inode allocation functions.
   */
  
  /*
   * Allocate an inode on disk.
   * Mode is used to tell whether the new inode will need space, and whether
   * it is a directory.
   *
   * The arguments IO_agbp and alloc_done are defined to work within
   * the constraint of one allocation per transaction.
   * xfs_dialloc() is designed to be called twice if it has to do an
   * allocation to make more free inodes.  On the first call,
   * IO_agbp should be set to NULL. If an inode is available,
   * i.e., xfs_dialloc() did not need to do an allocation, an inode
   * number is returned.  In this case, IO_agbp would be set to the
   * current ag_buf and alloc_done set to false.
   * If an allocation needed to be done, xfs_dialloc would return
   * the current ag_buf in IO_agbp and set alloc_done to true.
   * The caller should then commit the current transaction, allocate a new
   * transaction, and call xfs_dialloc() again, passing in the previous
   * value of IO_agbp.  IO_agbp should be held across the transactions.
   * Since the agbp is locked across the two calls, the second call is
   * guaranteed to have a free inode available.
   *
   * Once we successfully pick an inode its number is returned and the
   * on-disk data structures are updated.  The inode itself is not read
   * in, since doing so would break ordering constraints with xfs_reclaim.
   */
  int
  xfs_dialloc(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_ino_t	parent,		/* parent inode (directory) */

  	umode_t		mode,		/* mode bits for new inode */

  	int		okalloc,	/* ok to allocate more space */
  	xfs_buf_t	**IO_agbp,	/* in/out ag header's buffer */
  	boolean_t	*alloc_done,	/* true if we needed to replenish
  					   inode freelist */
  	xfs_ino_t	*inop)		/* inode number allocated */
  {
  	xfs_agnumber_t	agcount;	/* number of allocation groups */
  	xfs_buf_t	*agbp;		/* allocation group header's buffer */
  	xfs_agnumber_t	agno;		/* allocation group number */
  	xfs_agi_t	*agi;		/* allocation group header structure */
  	xfs_btree_cur_t	*cur;		/* inode allocation btree cursor */
  	int		error;		/* error return value */
  	int		i;		/* result code */
  	int		ialloced;	/* inode allocation status */
  	int		noroom = 0;	/* no space for inode blk allocation */
  	xfs_ino_t	ino;		/* fs-relative inode to be returned */
  	/* REFERENCED */
  	int		j;		/* result code */
  	xfs_mount_t	*mp;		/* file system mount structure */
  	int		offset;		/* index of inode in chunk */

  	xfs_agino_t	pagino;		/* parent's AG relative inode # */
  	xfs_agnumber_t	pagno;		/* parent's AG number */

  	xfs_inobt_rec_incore_t rec;	/* inode allocation record */

  	xfs_agnumber_t	tagno;		/* testing allocation group number */
  	xfs_btree_cur_t	*tcur;		/* temp cursor */

  	xfs_inobt_rec_incore_t trec;	/* temp inode allocation record */

  	struct xfs_perag *pag;

  
  
  	if (*IO_agbp == NULL) {
  		/*
  		 * We do not have an agbp, so select an initial allocation
  		 * group for inode allocation.
  		 */
  		agbp = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
  		/*
  		 * Couldn't find an allocation group satisfying the
  		 * criteria, give up.
  		 */
  		if (!agbp) {
  			*inop = NULLFSINO;
  			return 0;
  		}
  		agi = XFS_BUF_TO_AGI(agbp);

  		ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));

  	} else {
  		/*
  		 * Continue where we left off before.  In this case, we
  		 * know that the allocation group has free inodes.
  		 */
  		agbp = *IO_agbp;
  		agi = XFS_BUF_TO_AGI(agbp);

  		ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));

  		ASSERT(be32_to_cpu(agi->agi_freecount) > 0);

  	}
  	mp = tp->t_mountp;
  	agcount = mp->m_sb.sb_agcount;

  	agno = be32_to_cpu(agi->agi_seqno);

  	tagno = agno;
  	pagno = XFS_INO_TO_AGNO(mp, parent);
  	pagino = XFS_INO_TO_AGINO(mp, parent);
  
  	/*
  	 * If we have already hit the ceiling of inode blocks then clear
  	 * okalloc so we scan all available agi structures for a free
  	 * inode.
  	 */
  
  	if (mp->m_maxicount &&
  	    mp->m_sb.sb_icount + XFS_IALLOC_INODES(mp) > mp->m_maxicount) {
  		noroom = 1;
  		okalloc = 0;
  	}
  
  	/*
  	 * Loop until we find an allocation group that either has free inodes
  	 * or in which we can allocate some inodes.  Iterate through the
  	 * allocation groups upward, wrapping at the end.
  	 */
  	*alloc_done = B_FALSE;
  	while (!agi->agi_freecount) {
  		/*
  		 * Don't do anything if we're not supposed to allocate
  		 * any blocks, just go on to the next ag.
  		 */
  		if (okalloc) {
  			/*
  			 * Try to allocate some new inodes in the allocation
  			 * group.
  			 */
  			if ((error = xfs_ialloc_ag_alloc(tp, agbp, &ialloced))) {
  				xfs_trans_brelse(tp, agbp);
  				if (error == ENOSPC) {
  					*inop = NULLFSINO;
  					return 0;
  				} else
  					return error;
  			}
  			if (ialloced) {
  				/*
  				 * We successfully allocated some inodes, return
  				 * the current context to the caller so that it
  				 * can commit the current transaction and call
  				 * us again where we left off.
  				 */

  				ASSERT(be32_to_cpu(agi->agi_freecount) > 0);

  				*alloc_done = B_TRUE;
  				*IO_agbp = agbp;
  				*inop = NULLFSINO;
  				return 0;
  			}
  		}
  		/*
  		 * If it failed, give up on this ag.
  		 */
  		xfs_trans_brelse(tp, agbp);
  		/*
  		 * Go on to the next ag: get its ag header.
  		 */
  nextag:
  		if (++tagno == agcount)
  			tagno = 0;
  		if (tagno == agno) {
  			*inop = NULLFSINO;
  			return noroom ? ENOSPC : 0;
  		}

  		pag = xfs_perag_get(mp, tagno);
  		if (pag->pagi_inodeok == 0) {
  			xfs_perag_put(pag);

  			goto nextag;
  		}
  		error = xfs_ialloc_read_agi(mp, tp, tagno, &agbp);

  		xfs_perag_put(pag);

  		if (error)
  			goto nextag;
  		agi = XFS_BUF_TO_AGI(agbp);

  		ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));

  	}
  	/*
  	 * Here with an allocation group that has a free inode.
  	 * Reset agno since we may have chosen a new ag in the
  	 * loop above.
  	 */
  	agno = tagno;
  	*IO_agbp = NULL;

  	pag = xfs_perag_get(mp, agno);

  
   restart_pagno:

  	cur = xfs_inobt_init_cursor(mp, tp, agbp, be32_to_cpu(agi->agi_seqno));

  	/*
  	 * If pagino is 0 (this is the root inode allocation) use newino.
  	 * This must work because we've just allocated some.
  	 */
  	if (!pagino)

  		pagino = be32_to_cpu(agi->agi_newino);

  	error = xfs_check_agi_freecount(cur, agi);
  	if (error)
  		goto error0;

  	/*

  	 * If in the same AG as the parent, try to get near the parent.

  	 */
  	if (pagno == agno) {

  		int		doneleft;	/* done, to the left */
  		int		doneright;	/* done, to the right */

  		int		searchdistance = 10;

  		error = xfs_inobt_lookup(cur, pagino, XFS_LOOKUP_LE, &i);

  		if (error)

  			goto error0;

  		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  
  		error = xfs_inobt_get_rec(cur, &rec, &j);
  		if (error)
  			goto error0;
  		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  
  		if (rec.ir_freecount > 0) {

  			/*
  			 * Found a free inode in the same chunk

  			 * as the parent, done.

  			 */

  			goto alloc_inode;

  		}

  		/*

  		 * In the same AG as parent, but parent's chunk is full.

  		 */

  		/* duplicate the cursor, search left & right simultaneously */
  		error = xfs_btree_dup_cursor(cur, &tcur);
  		if (error)
  			goto error0;

  		/*
  		 * Skip to last blocks looked up if same parent inode.
  		 */
  		if (pagino != NULLAGINO &&
  		    pag->pagl_pagino == pagino &&
  		    pag->pagl_leftrec != NULLAGINO &&
  		    pag->pagl_rightrec != NULLAGINO) {
  			error = xfs_ialloc_get_rec(tcur, pag->pagl_leftrec,
  						   &trec, &doneleft, 1);
  			if (error)
  				goto error1;

  			error = xfs_ialloc_get_rec(cur, pag->pagl_rightrec,
  						   &rec, &doneright, 0);
  			if (error)
  				goto error1;
  		} else {
  			/* search left with tcur, back up 1 record */
  			error = xfs_ialloc_next_rec(tcur, &trec, &doneleft, 1);
  			if (error)
  				goto error1;
  
  			/* search right with cur, go forward 1 record. */
  			error = xfs_ialloc_next_rec(cur, &rec, &doneright, 0);
  			if (error)
  				goto error1;
  		}

  
  		/*
  		 * Loop until we find an inode chunk with a free inode.
  		 */
  		while (!doneleft || !doneright) {
  			int	useleft;  /* using left inode chunk this time */

  			if (!--searchdistance) {
  				/*
  				 * Not in range - save last search
  				 * location and allocate a new inode
  				 */

  				xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);

  				pag->pagl_leftrec = trec.ir_startino;
  				pag->pagl_rightrec = rec.ir_startino;
  				pag->pagl_pagino = pagino;
  				goto newino;
  			}

  			/* figure out the closer block if both are valid. */
  			if (!doneleft && !doneright) {
  				useleft = pagino -
  				 (trec.ir_startino + XFS_INODES_PER_CHUNK - 1) <
  				  rec.ir_startino - pagino;
  			} else {
  				useleft = !doneleft;

  			}

  
  			/* free inodes to the left? */
  			if (useleft && trec.ir_freecount) {
  				rec = trec;
  				xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  				cur = tcur;

  
  				pag->pagl_leftrec = trec.ir_startino;
  				pag->pagl_rightrec = rec.ir_startino;
  				pag->pagl_pagino = pagino;

  				goto alloc_inode;

  			}

  			/* free inodes to the right? */
  			if (!useleft && rec.ir_freecount) {
  				xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);

  
  				pag->pagl_leftrec = trec.ir_startino;
  				pag->pagl_rightrec = rec.ir_startino;
  				pag->pagl_pagino = pagino;

  				goto alloc_inode;

  			}

  
  			/* get next record to check */
  			if (useleft) {
  				error = xfs_ialloc_next_rec(tcur, &trec,
  								 &doneleft, 1);
  			} else {
  				error = xfs_ialloc_next_rec(cur, &rec,
  								 &doneright, 0);
  			}
  			if (error)
  				goto error1;

  		}

  
  		/*
  		 * We've reached the end of the btree. because
  		 * we are only searching a small chunk of the
  		 * btree each search, there is obviously free
  		 * inodes closer to the parent inode than we
  		 * are now. restart the search again.
  		 */
  		pag->pagl_pagino = NULLAGINO;
  		pag->pagl_leftrec = NULLAGINO;
  		pag->pagl_rightrec = NULLAGINO;
  		xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
  		xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  		goto restart_pagno;

  	}

  	/*

  	 * In a different AG from the parent.

  	 * See if the most recently allocated block has any free.
  	 */

  newino:

  	if (agi->agi_newino != cpu_to_be32(NULLAGINO)) {

  		error = xfs_inobt_lookup(cur, be32_to_cpu(agi->agi_newino),
  					 XFS_LOOKUP_EQ, &i);

  		if (error)

  			goto error0;

  
  		if (i == 1) {
  			error = xfs_inobt_get_rec(cur, &rec, &j);
  			if (error)
  				goto error0;
  
  			if (j == 1 && rec.ir_freecount > 0) {
  				/*
  				 * The last chunk allocated in the group
  				 * still has a free inode.
  				 */
  				goto alloc_inode;
  			}

  		}

  	}

  	/*
  	 * None left in the last group, search the whole AG
  	 */
  	error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &i);
  	if (error)
  		goto error0;
  	XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  
  	for (;;) {
  		error = xfs_inobt_get_rec(cur, &rec, &i);
  		if (error)
  			goto error0;
  		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  		if (rec.ir_freecount > 0)
  			break;
  		error = xfs_btree_increment(cur, 0, &i);

  		if (error)
  			goto error0;
  		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

  	}

  
  alloc_inode:

  	offset = xfs_ialloc_find_free(&rec.ir_free);

  	ASSERT(offset >= 0);
  	ASSERT(offset < XFS_INODES_PER_CHUNK);
  	ASSERT((XFS_AGINO_TO_OFFSET(mp, rec.ir_startino) %
  				   XFS_INODES_PER_CHUNK) == 0);
  	ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino + offset);

  	rec.ir_free &= ~XFS_INOBT_MASK(offset);

  	rec.ir_freecount--;

  	error = xfs_inobt_update(cur, &rec);
  	if (error)

  		goto error0;

  	be32_add_cpu(&agi->agi_freecount, -1);

  	xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);

  	pag->pagi_freecount--;

  	error = xfs_check_agi_freecount(cur, agi);
  	if (error)
  		goto error0;

  	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  	xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -1);

  	xfs_perag_put(pag);

  	*inop = ino;
  	return 0;
  error1:
  	xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
  error0:
  	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);

  	xfs_perag_put(pag);

  	return error;
  }
  
  /*
   * Free disk inode.  Carefully avoids touching the incore inode, all
   * manipulations incore are the caller's responsibility.
   * The on-disk inode is not changed by this operation, only the
   * btree (free inode mask) is changed.
   */
  int
  xfs_difree(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_ino_t	inode,		/* inode to be freed */
  	xfs_bmap_free_t	*flist,		/* extents to free */
  	int		*delete,	/* set if inode cluster was deleted */
  	xfs_ino_t	*first_ino)	/* first inode in deleted cluster */
  {
  	/* REFERENCED */
  	xfs_agblock_t	agbno;	/* block number containing inode */
  	xfs_buf_t	*agbp;	/* buffer containing allocation group header */
  	xfs_agino_t	agino;	/* inode number relative to allocation group */
  	xfs_agnumber_t	agno;	/* allocation group number */
  	xfs_agi_t	*agi;	/* allocation group header */
  	xfs_btree_cur_t	*cur;	/* inode btree cursor */
  	int		error;	/* error return value */
  	int		i;	/* result code */
  	int		ilen;	/* inodes in an inode cluster */
  	xfs_mount_t	*mp;	/* mount structure for filesystem */
  	int		off;	/* offset of inode in inode chunk */

  	xfs_inobt_rec_incore_t rec;	/* btree record */

  	struct xfs_perag *pag;

  
  	mp = tp->t_mountp;
  
  	/*
  	 * Break up inode number into its components.
  	 */
  	agno = XFS_INO_TO_AGNO(mp, inode);
  	if (agno >= mp->m_sb.sb_agcount)  {

  		xfs_warn(mp, "%s: agno >= mp->m_sb.sb_agcount (%d >= %d).",
  			__func__, agno, mp->m_sb.sb_agcount);

  		ASSERT(0);
  		return XFS_ERROR(EINVAL);
  	}
  	agino = XFS_INO_TO_AGINO(mp, inode);
  	if (inode != XFS_AGINO_TO_INO(mp, agno, agino))  {

  		xfs_warn(mp, "%s: inode != XFS_AGINO_TO_INO() (%llu != %llu).",
  			__func__, (unsigned long long)inode,
  			(unsigned long long)XFS_AGINO_TO_INO(mp, agno, agino));

  		ASSERT(0);
  		return XFS_ERROR(EINVAL);
  	}
  	agbno = XFS_AGINO_TO_AGBNO(mp, agino);
  	if (agbno >= mp->m_sb.sb_agblocks)  {

  		xfs_warn(mp, "%s: agbno >= mp->m_sb.sb_agblocks (%d >= %d).",
  			__func__, agbno, mp->m_sb.sb_agblocks);

  		ASSERT(0);
  		return XFS_ERROR(EINVAL);
  	}
  	/*
  	 * Get the allocation group header.
  	 */

  	error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);

  	if (error) {

  		xfs_warn(mp, "%s: xfs_ialloc_read_agi() returned error %d.",
  			__func__, error);

  		return error;
  	}
  	agi = XFS_BUF_TO_AGI(agbp);

  	ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));

  	ASSERT(agbno < be32_to_cpu(agi->agi_length));

  	/*
  	 * Initialize the cursor.
  	 */

  	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno);

  	error = xfs_check_agi_freecount(cur, agi);
  	if (error)
  		goto error0;

  	/*
  	 * Look for the entry describing this inode.
  	 */

  	if ((error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &i))) {

  		xfs_warn(mp, "%s: xfs_inobt_lookup() returned error %d.",
  			__func__, error);

  		goto error0;
  	}
  	XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

  	error = xfs_inobt_get_rec(cur, &rec, &i);
  	if (error) {

  		xfs_warn(mp, "%s: xfs_inobt_get_rec() returned error %d.",
  			__func__, error);

  		goto error0;
  	}
  	XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  	/*
  	 * Get the offset in the inode chunk.
  	 */
  	off = agino - rec.ir_startino;
  	ASSERT(off >= 0 && off < XFS_INODES_PER_CHUNK);

  	ASSERT(!(rec.ir_free & XFS_INOBT_MASK(off)));

  	/*
  	 * Mark the inode free & increment the count.
  	 */

  	rec.ir_free |= XFS_INOBT_MASK(off);

  	rec.ir_freecount++;
  
  	/*

  	 * When an inode cluster is free, it becomes eligible for removal

  	 */

  	if (!(mp->m_flags & XFS_MOUNT_IKEEP) &&

  	    (rec.ir_freecount == XFS_IALLOC_INODES(mp))) {
  
  		*delete = 1;
  		*first_ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino);
  
  		/*
  		 * Remove the inode cluster from the AGI B+Tree, adjust the
  		 * AGI and Superblock inode counts, and mark the disk space
  		 * to be freed when the transaction is committed.
  		 */
  		ilen = XFS_IALLOC_INODES(mp);

  		be32_add_cpu(&agi->agi_count, -ilen);
  		be32_add_cpu(&agi->agi_freecount, -(ilen - 1));

  		xfs_ialloc_log_agi(tp, agbp, XFS_AGI_COUNT | XFS_AGI_FREECOUNT);

  		pag = xfs_perag_get(mp, agno);
  		pag->pagi_freecount -= ilen - 1;
  		xfs_perag_put(pag);

  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_ICOUNT, -ilen);
  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -(ilen - 1));

  		if ((error = xfs_btree_delete(cur, &i))) {

  			xfs_warn(mp, "%s: xfs_btree_delete returned error %d.",
  				__func__, error);

  			goto error0;
  		}
  
  		xfs_bmap_add_free(XFS_AGB_TO_FSB(mp,
  				agno, XFS_INO_TO_AGBNO(mp,rec.ir_startino)),
  				XFS_IALLOC_BLOCKS(mp), flist, mp);
  	} else {
  		*delete = 0;

  		error = xfs_inobt_update(cur, &rec);
  		if (error) {

  			xfs_warn(mp, "%s: xfs_inobt_update returned error %d.",
  				__func__, error);

  			goto error0;
  		}

  		/* 
  		 * Change the inode free counts and log the ag/sb changes.
  		 */

  		be32_add_cpu(&agi->agi_freecount, 1);

  		xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);

  		pag = xfs_perag_get(mp, agno);
  		pag->pagi_freecount++;
  		xfs_perag_put(pag);

  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, 1);
  	}

  	error = xfs_check_agi_freecount(cur, agi);
  	if (error)
  		goto error0;

  	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  	return 0;
  
  error0:
  	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  	return error;
  }

  STATIC int
  xfs_imap_lookup(
  	struct xfs_mount	*mp,
  	struct xfs_trans	*tp,
  	xfs_agnumber_t		agno,
  	xfs_agino_t		agino,
  	xfs_agblock_t		agbno,
  	xfs_agblock_t		*chunk_agbno,
  	xfs_agblock_t		*offset_agbno,
  	int			flags)
  {
  	struct xfs_inobt_rec_incore rec;
  	struct xfs_btree_cur	*cur;
  	struct xfs_buf		*agbp;

  	int			error;
  	int			i;
  
  	error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
  	if (error) {

  		xfs_alert(mp,
  			"%s: xfs_ialloc_read_agi() returned error %d, agno %d",
  			__func__, error, agno);

  		return error;
  	}
  
  	/*

  	 * Lookup the inode record for the given agino. If the record cannot be
  	 * found, then it's an invalid inode number and we should abort. Once
  	 * we have a record, we need to ensure it contains the inode number
  	 * we are looking up.

  	 */
  	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno);

  	error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &i);

  	if (!error) {
  		if (i)
  			error = xfs_inobt_get_rec(cur, &rec, &i);
  		if (!error && i == 0)
  			error = EINVAL;
  	}
  
  	xfs_trans_brelse(tp, agbp);
  	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  	if (error)
  		return error;

  	/* check that the returned record contains the required inode */
  	if (rec.ir_startino > agino ||
  	    rec.ir_startino + XFS_IALLOC_INODES(mp) <= agino)
  		return EINVAL;

  	/* for untrusted inodes check it is allocated first */

  	if ((flags & XFS_IGET_UNTRUSTED) &&

  	    (rec.ir_free & XFS_INOBT_MASK(agino - rec.ir_startino)))
  		return EINVAL;
  
  	*chunk_agbno = XFS_AGINO_TO_AGBNO(mp, rec.ir_startino);
  	*offset_agbno = agbno - *chunk_agbno;
  	return 0;
  }

  /*

   * Return the location of the inode in imap, for mapping it into a buffer.

   */

  int

  xfs_imap(
  	xfs_mount_t	 *mp,	/* file system mount structure */
  	xfs_trans_t	 *tp,	/* transaction pointer */

  	xfs_ino_t	ino,	/* inode to locate */

  	struct xfs_imap	*imap,	/* location map structure */
  	uint		flags)	/* flags for inode btree lookup */

  {
  	xfs_agblock_t	agbno;	/* block number of inode in the alloc group */

  	xfs_agino_t	agino;	/* inode number within alloc group */
  	xfs_agnumber_t	agno;	/* allocation group number */
  	int		blks_per_cluster; /* num blocks per inode cluster */
  	xfs_agblock_t	chunk_agbno;	/* first block in inode chunk */

  	xfs_agblock_t	cluster_agbno;	/* first block in inode cluster */

  	int		error;	/* error code */

  	int		offset;	/* index of inode in its buffer */
  	int		offset_agbno;	/* blks from chunk start to inode */
  
  	ASSERT(ino != NULLFSINO);

  	/*
  	 * Split up the inode number into its parts.
  	 */
  	agno = XFS_INO_TO_AGNO(mp, ino);
  	agino = XFS_INO_TO_AGINO(mp, ino);
  	agbno = XFS_AGINO_TO_AGBNO(mp, agino);
  	if (agno >= mp->m_sb.sb_agcount || agbno >= mp->m_sb.sb_agblocks ||
  	    ino != XFS_AGINO_TO_INO(mp, agno, agino)) {
  #ifdef DEBUG

  		/*
  		 * Don't output diagnostic information for untrusted inodes
  		 * as they can be invalid without implying corruption.
  		 */
  		if (flags & XFS_IGET_UNTRUSTED)

  			return XFS_ERROR(EINVAL);

  		if (agno >= mp->m_sb.sb_agcount) {

  			xfs_alert(mp,
  				"%s: agno (%d) >= mp->m_sb.sb_agcount (%d)",
  				__func__, agno, mp->m_sb.sb_agcount);

  		}
  		if (agbno >= mp->m_sb.sb_agblocks) {

  			xfs_alert(mp,
  		"%s: agbno (0x%llx) >= mp->m_sb.sb_agblocks (0x%lx)",
  				__func__, (unsigned long long)agbno,
  				(unsigned long)mp->m_sb.sb_agblocks);

  		}
  		if (ino != XFS_AGINO_TO_INO(mp, agno, agino)) {

  			xfs_alert(mp,
  		"%s: ino (0x%llx) != XFS_AGINO_TO_INO() (0x%llx)",
  				__func__, ino,
  				XFS_AGINO_TO_INO(mp, agno, agino));

  		}

  		xfs_stack_trace();

  #endif /* DEBUG */
  		return XFS_ERROR(EINVAL);
  	}

  	blks_per_cluster = XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_blocklog;
  
  	/*
  	 * For bulkstat and handle lookups, we have an untrusted inode number
  	 * that we have to verify is valid. We cannot do this just by reading
  	 * the inode buffer as it may have been unlinked and removed leaving
  	 * inodes in stale state on disk. Hence we have to do a btree lookup
  	 * in all cases where an untrusted inode number is passed.
  	 */

  	if (flags & XFS_IGET_UNTRUSTED) {

  		error = xfs_imap_lookup(mp, tp, agno, agino, agbno,
  					&chunk_agbno, &offset_agbno, flags);
  		if (error)
  			return error;
  		goto out_map;
  	}

  	/*
  	 * If the inode cluster size is the same as the blocksize or
  	 * smaller we get to the buffer by simple arithmetics.
  	 */
  	if (XFS_INODE_CLUSTER_SIZE(mp) <= mp->m_sb.sb_blocksize) {

  		offset = XFS_INO_TO_OFFSET(mp, ino);
  		ASSERT(offset < mp->m_sb.sb_inopblock);

  
  		imap->im_blkno = XFS_AGB_TO_DADDR(mp, agno, agbno);
  		imap->im_len = XFS_FSB_TO_BB(mp, 1);
  		imap->im_boffset = (ushort)(offset << mp->m_sb.sb_inodelog);

  		return 0;
  	}

  	/*

  	 * If the inode chunks are aligned then use simple maths to
  	 * find the location. Otherwise we have to do a btree
  	 * lookup to find the location.
  	 */

  	if (mp->m_inoalign_mask) {
  		offset_agbno = agbno & mp->m_inoalign_mask;
  		chunk_agbno = agbno - offset_agbno;
  	} else {

  		error = xfs_imap_lookup(mp, tp, agno, agino, agbno,
  					&chunk_agbno, &offset_agbno, flags);

  		if (error)
  			return error;

  	}

  out_map:

  	ASSERT(agbno >= chunk_agbno);
  	cluster_agbno = chunk_agbno +
  		((offset_agbno / blks_per_cluster) * blks_per_cluster);
  	offset = ((agbno - cluster_agbno) * mp->m_sb.sb_inopblock) +
  		XFS_INO_TO_OFFSET(mp, ino);

  
  	imap->im_blkno = XFS_AGB_TO_DADDR(mp, agno, cluster_agbno);
  	imap->im_len = XFS_FSB_TO_BB(mp, blks_per_cluster);
  	imap->im_boffset = (ushort)(offset << mp->m_sb.sb_inodelog);
  
  	/*
  	 * If the inode number maps to a block outside the bounds
  	 * of the file system then return NULL rather than calling
  	 * read_buf and panicing when we get an error from the
  	 * driver.
  	 */
  	if ((imap->im_blkno + imap->im_len) >
  	    XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks)) {

  		xfs_alert(mp,
  	"%s: (im_blkno (0x%llx) + im_len (0x%llx)) > sb_dblocks (0x%llx)",
  			__func__, (unsigned long long) imap->im_blkno,

  			(unsigned long long) imap->im_len,
  			XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks));
  		return XFS_ERROR(EINVAL);
  	}

  	return 0;

  }
  
  /*
   * Compute and fill in value of m_in_maxlevels.
   */
  void
  xfs_ialloc_compute_maxlevels(
  	xfs_mount_t	*mp)		/* file system mount structure */
  {
  	int		level;
  	uint		maxblocks;
  	uint		maxleafents;
  	int		minleafrecs;
  	int		minnoderecs;
  
  	maxleafents = (1LL << XFS_INO_AGINO_BITS(mp)) >>
  		XFS_INODES_PER_CHUNK_LOG;
  	minleafrecs = mp->m_alloc_mnr[0];
  	minnoderecs = mp->m_alloc_mnr[1];
  	maxblocks = (maxleafents + minleafrecs - 1) / minleafrecs;
  	for (level = 1; maxblocks > 1; level++)
  		maxblocks = (maxblocks + minnoderecs - 1) / minnoderecs;
  	mp->m_in_maxlevels = level;
  }
  
  /*
   * Log specified fields for the ag hdr (inode section)
   */
  void
  xfs_ialloc_log_agi(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_buf_t	*bp,		/* allocation group header buffer */
  	int		fields)		/* bitmask of fields to log */
  {
  	int			first;		/* first byte number */
  	int			last;		/* last byte number */
  	static const short	offsets[] = {	/* field starting offsets */
  					/* keep in sync with bit definitions */
  		offsetof(xfs_agi_t, agi_magicnum),
  		offsetof(xfs_agi_t, agi_versionnum),
  		offsetof(xfs_agi_t, agi_seqno),
  		offsetof(xfs_agi_t, agi_length),
  		offsetof(xfs_agi_t, agi_count),
  		offsetof(xfs_agi_t, agi_root),
  		offsetof(xfs_agi_t, agi_level),
  		offsetof(xfs_agi_t, agi_freecount),
  		offsetof(xfs_agi_t, agi_newino),
  		offsetof(xfs_agi_t, agi_dirino),
  		offsetof(xfs_agi_t, agi_unlinked),
  		sizeof(xfs_agi_t)
  	};
  #ifdef DEBUG
  	xfs_agi_t		*agi;	/* allocation group header */
  
  	agi = XFS_BUF_TO_AGI(bp);

  	ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));

  #endif
  	/*
  	 * Compute byte offsets for the first and last fields.
  	 */
  	xfs_btree_offsets(fields, offsets, XFS_AGI_NUM_BITS, &first, &last);
  	/*
  	 * Log the allocation group inode header buffer.
  	 */
  	xfs_trans_log_buf(tp, bp, first, last);
  }

  #ifdef DEBUG
  STATIC void
  xfs_check_agi_unlinked(
  	struct xfs_agi		*agi)
  {
  	int			i;
  
  	for (i = 0; i < XFS_AGI_UNLINKED_BUCKETS; i++)
  		ASSERT(agi->agi_unlinked[i]);
  }
  #else
  #define xfs_check_agi_unlinked(agi)
  #endif

  /*
   * Read in the allocation group header (inode allocation section)
   */
  int

  xfs_read_agi(
  	struct xfs_mount	*mp,	/* file system mount structure */
  	struct xfs_trans	*tp,	/* transaction pointer */
  	xfs_agnumber_t		agno,	/* allocation group number */
  	struct xfs_buf		**bpp)	/* allocation group hdr buf */

  {

  	struct xfs_agi		*agi;	/* allocation group header */
  	int			agi_ok;	/* agi is consistent */
  	int			error;

  
  	ASSERT(agno != NULLAGNUMBER);

  
  	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,

  			XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),

  			XFS_FSS_TO_BB(mp, 1), 0, bpp);

  	if (error)
  		return error;

  	ASSERT(!xfs_buf_geterror(*bpp));

  	agi = XFS_BUF_TO_AGI(*bpp);

  
  	/*
  	 * Validate the magic number of the agi block.
  	 */

  	agi_ok = agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC) &&

  		XFS_AGI_GOOD_VERSION(be32_to_cpu(agi->agi_versionnum)) &&
  		be32_to_cpu(agi->agi_seqno) == agno;

  	if (unlikely(XFS_TEST_ERROR(!agi_ok, mp, XFS_ERRTAG_IALLOC_READ_AGI,
  			XFS_RANDOM_IALLOC_READ_AGI))) {

  		XFS_CORRUPTION_ERROR("xfs_read_agi", XFS_ERRLEVEL_LOW,

  				     mp, agi);

  		xfs_trans_brelse(tp, *bpp);

  		return XFS_ERROR(EFSCORRUPTED);
  	}

  	xfs_buf_set_ref(*bpp, XFS_AGI_REF);

  
  	xfs_check_agi_unlinked(agi);
  	return 0;
  }
  
  int
  xfs_ialloc_read_agi(
  	struct xfs_mount	*mp,	/* file system mount structure */
  	struct xfs_trans	*tp,	/* transaction pointer */
  	xfs_agnumber_t		agno,	/* allocation group number */
  	struct xfs_buf		**bpp)	/* allocation group hdr buf */
  {
  	struct xfs_agi		*agi;	/* allocation group header */
  	struct xfs_perag	*pag;	/* per allocation group data */
  	int			error;
  
  	error = xfs_read_agi(mp, tp, agno, bpp);
  	if (error)
  		return error;
  
  	agi = XFS_BUF_TO_AGI(*bpp);

  	pag = xfs_perag_get(mp, agno);

  	if (!pag->pagi_init) {

  		pag->pagi_freecount = be32_to_cpu(agi->agi_freecount);

  		pag->pagi_count = be32_to_cpu(agi->agi_count);

  		pag->pagi_init = 1;

  	}

  	/*
  	 * It's possible for these to be out of sync if
  	 * we are in the middle of a forced shutdown.
  	 */
  	ASSERT(pag->pagi_freecount == be32_to_cpu(agi->agi_freecount) ||
  		XFS_FORCED_SHUTDOWN(mp));

  	xfs_perag_put(pag);

  	return 0;
  }

  
  /*
   * Read in the agi to initialise the per-ag data in the mount structure
   */
  int
  xfs_ialloc_pagi_init(
  	xfs_mount_t	*mp,		/* file system mount structure */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_agnumber_t	agno)		/* allocation group number */
  {
  	xfs_buf_t	*bp = NULL;
  	int		error;
  
  	error = xfs_ialloc_read_agi(mp, tp, agno, &bp);
  	if (error)
  		return error;
  	if (bp)
  		xfs_trans_brelse(tp, bp);
  	return 0;
  }