/*

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

   *

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

   * published by the Free Software Foundation.
   *

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

   *

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

   */

  #include "xfs.h"

  #include "xfs_fs.h"

  #include "xfs_types.h"

  #include "xfs_bit.h"

  #include "xfs_log.h"

  #include "xfs_inum.h"

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

  #include "xfs_dir2.h"
  #include "xfs_dmapi.h"
  #include "xfs_mount.h"

  #include "xfs_bmap_btree.h"

  #include "xfs_alloc_btree.h"

  #include "xfs_ialloc_btree.h"

  #include "xfs_dir2_sf.h"

  #include "xfs_attr_sf.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"
  
  /*
   * Log specified fields for the inode given by bp and off.
   */
  STATIC void
  xfs_ialloc_log_di(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_buf_t	*bp,		/* inode buffer */
  	int		off,		/* index of inode in buffer */
  	int		fields)		/* bitmask of fields to log */
  {
  	int			first;		/* first byte number */
  	int			ioffset;	/* off in bytes */
  	int			last;		/* last byte number */
  	xfs_mount_t		*mp;		/* mount point structure */
  	static const short	offsets[] = {	/* field offsets */
  						/* keep in sync with bits */
  		offsetof(xfs_dinode_core_t, di_magic),
  		offsetof(xfs_dinode_core_t, di_mode),
  		offsetof(xfs_dinode_core_t, di_version),
  		offsetof(xfs_dinode_core_t, di_format),
  		offsetof(xfs_dinode_core_t, di_onlink),
  		offsetof(xfs_dinode_core_t, di_uid),
  		offsetof(xfs_dinode_core_t, di_gid),
  		offsetof(xfs_dinode_core_t, di_nlink),
  		offsetof(xfs_dinode_core_t, di_projid),
  		offsetof(xfs_dinode_core_t, di_pad),
  		offsetof(xfs_dinode_core_t, di_atime),
  		offsetof(xfs_dinode_core_t, di_mtime),
  		offsetof(xfs_dinode_core_t, di_ctime),
  		offsetof(xfs_dinode_core_t, di_size),
  		offsetof(xfs_dinode_core_t, di_nblocks),
  		offsetof(xfs_dinode_core_t, di_extsize),
  		offsetof(xfs_dinode_core_t, di_nextents),
  		offsetof(xfs_dinode_core_t, di_anextents),
  		offsetof(xfs_dinode_core_t, di_forkoff),
  		offsetof(xfs_dinode_core_t, di_aformat),
  		offsetof(xfs_dinode_core_t, di_dmevmask),
  		offsetof(xfs_dinode_core_t, di_dmstate),
  		offsetof(xfs_dinode_core_t, di_flags),
  		offsetof(xfs_dinode_core_t, di_gen),
  		offsetof(xfs_dinode_t, di_next_unlinked),
  		offsetof(xfs_dinode_t, di_u),
  		offsetof(xfs_dinode_t, di_a),
  		sizeof(xfs_dinode_t)
  	};
  
  
  	ASSERT(offsetof(xfs_dinode_t, di_core) == 0);
  	ASSERT((fields & (XFS_DI_U|XFS_DI_A)) == 0);
  	mp = tp->t_mountp;
  	/*
  	 * Get the inode-relative first and last bytes for these fields
  	 */
  	xfs_btree_offsets(fields, offsets, XFS_DI_NUM_BITS, &first, &last);
  	/*
  	 * Convert to buffer offsets and log it.
  	 */
  	ioffset = off << mp->m_sb.sb_inodelog;
  	first += ioffset;
  	last += ioffset;
  	xfs_trans_log_buf(tp, bp, first, last);
  }
  
  /*
   * Allocation group level functions.
   */
  
  /*
   * 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 */
  	int		blks_per_cluster;  /* fs blocks per inode cluster */
  	xfs_btree_cur_t	*cur;		/* inode btree cursor */
  	xfs_daddr_t	d;		/* disk addr of buffer */

  	xfs_agnumber_t	agno;

  	int		error;
  	xfs_buf_t	*fbuf;		/* new free inodes' buffer */
  	xfs_dinode_t	*free;		/* new free inode structure */
  	int		i;		/* inode counter */
  	int		j;		/* block counter */
  	int		nbufs;		/* num bufs of new inodes */
  	xfs_agino_t	newino;		/* new first inode's number */
  	xfs_agino_t	newlen;		/* new number of inodes */
  	int		ninodes;	/* num inodes per buf */
  	xfs_agino_t	thisino;	/* current inode number, for loop */
  	int		version;	/* inode version number to use */

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

  					/* boundary */

  
  	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);

  	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,
  				be32_to_cpu(agi->agi_seqno), args.agbno);
  		args.type = XFS_ALLOCTYPE_THIS_BNO;
  		args.mod = args.total = args.wasdel = args.isfl =
  			args.userdata = args.minalignslop = 0;
  		args.prod = 1;
  		args.alignment = 1;
  		/*
  		 * Allow space for the inode btree to split.
  		 */
  		args.minleft = XFS_IN_MAXLEVELS(args.mp) - 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 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)))
  				args.alignment = args.mp->m_sb.sb_inoalignmt;
  		else
  			args.alignment = 1;
  		/*
  		 * 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,
  				be32_to_cpu(agi->agi_seqno), 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 = XFS_IN_MAXLEVELS(args.mp) - 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,

  				be32_to_cpu(agi->agi_seqno), args.agbno);

  		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)))
  				args.alignment = args.mp->m_sb.sb_inoalignmt;
  		else
  			args.alignment = 1;
  		if ((error = xfs_alloc_vextent(&args)))
  			return error;
  	}
  
  	if (args.fsbno == NULLFSBLOCK) {
  		*alloc = 0;
  		return 0;
  	}
  	ASSERT(args.len == args.minlen);
  	/*
  	 * Convert the results.
  	 */
  	newino = XFS_OFFBNO_TO_AGINO(args.mp, args.agbno, 0);
  	/*
  	 * 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 (args.mp->m_sb.sb_blocksize >= XFS_INODE_CLUSTER_SIZE(args.mp)) {
  		blks_per_cluster = 1;
  		nbufs = (int)args.len;
  		ninodes = args.mp->m_sb.sb_inopblock;
  	} else {
  		blks_per_cluster = XFS_INODE_CLUSTER_SIZE(args.mp) /
  				   args.mp->m_sb.sb_blocksize;
  		nbufs = (int)args.len / blks_per_cluster;
  		ninodes = blks_per_cluster * args.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(&args.mp->m_sb))
  		version = XFS_DINODE_VERSION_2;
  	else
  		version = XFS_DINODE_VERSION_1;

  	for (j = 0; j < nbufs; j++) {
  		/*
  		 * Get the block.
  		 */

  		d = XFS_AGB_TO_DADDR(args.mp, be32_to_cpu(agi->agi_seqno),

  				     args.agbno + (j * blks_per_cluster));
  		fbuf = xfs_trans_get_buf(tp, args.mp->m_ddev_targp, d,
  					 args.mp->m_bsize * blks_per_cluster,
  					 XFS_BUF_LOCK);
  		ASSERT(fbuf);
  		ASSERT(!XFS_BUF_GETERROR(fbuf));
  		/*

  		 * Set initial values for the inodes in this buffer.

  		 */

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

  		for (i = 0; i < ninodes; i++) {
  			free = XFS_MAKE_IPTR(args.mp, fbuf, i);

  			INT_SET(free->di_core.di_magic, ARCH_CONVERT, XFS_DINODE_MAGIC);
  			INT_SET(free->di_core.di_version, ARCH_CONVERT, version);

  			INT_SET(free->di_next_unlinked, ARCH_CONVERT, NULLAGINO);
  			xfs_ialloc_log_di(tp, fbuf, i,
  				XFS_DI_CORE_BITS | XFS_DI_NEXT_UNLINKED);
  		}
  		xfs_trans_inode_alloc_buf(tp, fbuf);
  	}

  	be32_add(&agi->agi_count, newlen);
  	be32_add(&agi->agi_freecount, newlen);

  	agno = be32_to_cpu(agi->agi_seqno);

  	down_read(&args.mp->m_peraglock);

  	args.mp->m_perag[agno].pagi_freecount += newlen;

  	up_read(&args.mp->m_peraglock);

  	agi->agi_newino = cpu_to_be32(newino);

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

  	cur = xfs_btree_init_cursor(args.mp, tp, agbp, agno,

  			XFS_BTNUM_INO, (xfs_inode_t *)0, 0);
  	for (thisino = newino;
  	     thisino < newino + newlen;
  	     thisino += XFS_INODES_PER_CHUNK) {
  		if ((error = xfs_inobt_lookup_eq(cur, thisino,
  				XFS_INODES_PER_CHUNK, XFS_INOBT_ALL_FREE, &i))) {
  			xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  			return error;
  		}
  		ASSERT(i == 0);
  		if ((error = xfs_inobt_insert(cur, &i))) {
  			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_INLINE 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 */
  	mode_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;
  	down_read(&mp->m_peraglock);
  	for (;;) {
  		pag = &mp->m_perag[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;
  				}
  				up_read(&mp->m_peraglock);
  				return agbp;
  			}
  		}
  unlock_nextag:
  		if (agbp)
  			xfs_trans_brelse(tp, agbp);
  nextag:
  		/*
  		 * No point in iterating over the rest, if we're shutting
  		 * down.
  		 */
  		if (XFS_FORCED_SHUTDOWN(mp)) {
  			up_read(&mp->m_peraglock);

  			return NULL;

  		}
  		agno++;
  		if (agno >= agcount)
  			agno = 0;
  		if (agno == pagno) {
  			if (flags == 0) {
  				up_read(&mp->m_peraglock);

  				return NULL;

  			}
  			flags = 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) */
  	mode_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 a.g. relative inode # */
  	xfs_agnumber_t	pagno;		/* parent's allocation group 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 */

  
  
  	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(be32_to_cpu(agi->agi_magicnum) == 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(be32_to_cpu(agi->agi_magicnum) == 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;
  		}
  		down_read(&mp->m_peraglock);
  		if (mp->m_perag[tagno].pagi_inodeok == 0) {
  			up_read(&mp->m_peraglock);
  			goto nextag;
  		}
  		error = xfs_ialloc_read_agi(mp, tp, tagno, &agbp);
  		up_read(&mp->m_peraglock);
  		if (error)
  			goto nextag;
  		agi = XFS_BUF_TO_AGI(agbp);

  		ASSERT(be32_to_cpu(agi->agi_magicnum) == 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;

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

  				    XFS_BTNUM_INO, (xfs_inode_t *)0, 0);
  	/*
  	 * 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);

  #ifdef DEBUG
  	if (cur->bc_nlevels == 1) {
  		int	freecount = 0;
  
  		if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
  			goto error0;
  		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  		do {
  			if ((error = xfs_inobt_get_rec(cur, &rec.ir_startino,
  					&rec.ir_freecount, &rec.ir_free, &i)))
  				goto error0;
  			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  			freecount += rec.ir_freecount;
  			if ((error = xfs_inobt_increment(cur, 0, &i)))
  				goto error0;
  		} while (i == 1);

  		ASSERT(freecount == be32_to_cpu(agi->agi_freecount) ||

  		       XFS_FORCED_SHUTDOWN(mp));
  	}
  #endif
  	/*
  	 * If in the same a.g. as the parent, try to get near the parent.
  	 */
  	if (pagno == agno) {
  		if ((error = xfs_inobt_lookup_le(cur, pagino, 0, 0, &i)))
  			goto error0;
  		if (i != 0 &&
  		    (error = xfs_inobt_get_rec(cur, &rec.ir_startino,
  			    &rec.ir_freecount, &rec.ir_free, &j)) == 0 &&
  		    j == 1 &&
  		    rec.ir_freecount > 0) {
  			/*
  			 * Found a free inode in the same chunk
  			 * as parent, done.
  			 */
  		}
  		/*
  		 * In the same a.g. as parent, but parent's chunk is full.
  		 */
  		else {
  			int	doneleft;	/* done, to the left */
  			int	doneright;	/* done, to the right */
  
  			if (error)
  				goto error0;
  			ASSERT(i == 1);
  			ASSERT(j == 1);
  			/*
  			 * Duplicate the cursor, search left & right
  			 * simultaneously.
  			 */
  			if ((error = xfs_btree_dup_cursor(cur, &tcur)))
  				goto error0;
  			/*
  			 * Search left with tcur, back up 1 record.
  			 */
  			if ((error = xfs_inobt_decrement(tcur, 0, &i)))
  				goto error1;
  			doneleft = !i;
  			if (!doneleft) {
  				if ((error = xfs_inobt_get_rec(tcur,
  						&trec.ir_startino,
  						&trec.ir_freecount,
  						&trec.ir_free, &i)))
  					goto error1;
  				XFS_WANT_CORRUPTED_GOTO(i == 1, error1);
  			}
  			/*
  			 * Search right with cur, go forward 1 record.
  			 */
  			if ((error = xfs_inobt_increment(cur, 0, &i)))
  				goto error1;
  			doneright = !i;
  			if (!doneright) {
  				if ((error = xfs_inobt_get_rec(cur,
  						&rec.ir_startino,
  						&rec.ir_freecount,
  						&rec.ir_free, &i)))
  					goto error1;
  				XFS_WANT_CORRUPTED_GOTO(i == 1, error1);
  			}
  			/*
  			 * Loop until we find the closest inode chunk
  			 * with a free one.
  			 */
  			while (!doneleft || !doneright) {
  				int	useleft;  /* using left inode
  						     chunk this time */
  
  				/*
  				 * Figure out which block is closer,
  				 * if both are valid.
  				 */
  				if (!doneleft && !doneright)
  					useleft =
  						pagino -
  						(trec.ir_startino +
  						 XFS_INODES_PER_CHUNK - 1) <
  						 rec.ir_startino - pagino;
  				else
  					useleft = !doneleft;
  				/*
  				 * If checking the left, does it have
  				 * free inodes?
  				 */
  				if (useleft && trec.ir_freecount) {
  					/*
  					 * Yes, set it up as the chunk to use.
  					 */
  					rec = trec;
  					xfs_btree_del_cursor(cur,
  						XFS_BTREE_NOERROR);
  					cur = tcur;
  					break;
  				}
  				/*
  				 * If checking the right, does it have
  				 * free inodes?
  				 */
  				if (!useleft && rec.ir_freecount) {
  					/*
  					 * Yes, it's already set up.
  					 */
  					xfs_btree_del_cursor(tcur,
  						XFS_BTREE_NOERROR);
  					break;
  				}
  				/*
  				 * If used the left, get another one
  				 * further left.
  				 */
  				if (useleft) {
  					if ((error = xfs_inobt_decrement(tcur, 0,
  							&i)))
  						goto error1;
  					doneleft = !i;
  					if (!doneleft) {
  						if ((error = xfs_inobt_get_rec(
  							    tcur,
  							    &trec.ir_startino,
  							    &trec.ir_freecount,
  							    &trec.ir_free, &i)))
  							goto error1;
  						XFS_WANT_CORRUPTED_GOTO(i == 1,
  							error1);
  					}
  				}
  				/*
  				 * If used the right, get another one
  				 * further right.
  				 */
  				else {
  					if ((error = xfs_inobt_increment(cur, 0,
  							&i)))
  						goto error1;
  					doneright = !i;
  					if (!doneright) {
  						if ((error = xfs_inobt_get_rec(
  							    cur,
  							    &rec.ir_startino,
  							    &rec.ir_freecount,
  							    &rec.ir_free, &i)))
  							goto error1;
  						XFS_WANT_CORRUPTED_GOTO(i == 1,
  							error1);
  					}
  				}
  			}
  			ASSERT(!doneleft || !doneright);
  		}
  	}
  	/*
  	 * In a different a.g. from the parent.
  	 * See if the most recently allocated block has any free.
  	 */

  	else if (be32_to_cpu(agi->agi_newino) != NULLAGINO) {

  		if ((error = xfs_inobt_lookup_eq(cur,

  				be32_to_cpu(agi->agi_newino), 0, 0, &i)))

  			goto error0;
  		if (i == 1 &&
  		    (error = xfs_inobt_get_rec(cur, &rec.ir_startino,
  			    &rec.ir_freecount, &rec.ir_free, &j)) == 0 &&
  		    j == 1 &&
  		    rec.ir_freecount > 0) {
  			/*
  			 * The last chunk allocated in the group still has
  			 * a free inode.
  			 */
  		}
  		/*
  		 * None left in the last group, search the whole a.g.
  		 */
  		else {
  			if (error)
  				goto error0;
  			if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
  				goto error0;
  			ASSERT(i == 1);
  			for (;;) {
  				if ((error = xfs_inobt_get_rec(cur,
  						&rec.ir_startino,
  						&rec.ir_freecount, &rec.ir_free,
  						&i)))
  					goto error0;
  				XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  				if (rec.ir_freecount > 0)
  					break;
  				if ((error = xfs_inobt_increment(cur, 0, &i)))
  					goto error0;
  				XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  			}
  		}
  	}
  	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);
  	XFS_INOBT_CLR_FREE(&rec, offset);
  	rec.ir_freecount--;
  	if ((error = xfs_inobt_update(cur, rec.ir_startino, rec.ir_freecount,
  			rec.ir_free)))
  		goto error0;

  	be32_add(&agi->agi_freecount, -1);

  	xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
  	down_read(&mp->m_peraglock);
  	mp->m_perag[tagno].pagi_freecount--;
  	up_read(&mp->m_peraglock);
  #ifdef DEBUG
  	if (cur->bc_nlevels == 1) {
  		int	freecount = 0;
  
  		if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
  			goto error0;
  		do {
  			if ((error = xfs_inobt_get_rec(cur, &rec.ir_startino,
  					&rec.ir_freecount, &rec.ir_free, &i)))
  				goto error0;
  			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  			freecount += rec.ir_freecount;
  			if ((error = xfs_inobt_increment(cur, 0, &i)))
  				goto error0;
  		} while (i == 1);

  		ASSERT(freecount == be32_to_cpu(agi->agi_freecount) ||

  		       XFS_FORCED_SHUTDOWN(mp));
  	}
  #endif
  	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  	xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -1);
  	*inop = ino;
  	return 0;
  error1:
  	xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
  error0:
  	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  	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 */

  
  	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)  {
  		cmn_err(CE_WARN,
  			"xfs_difree: agno >= mp->m_sb.sb_agcount (%d >= %d) on %s.  Returning EINVAL.",
  			agno, mp->m_sb.sb_agcount, mp->m_fsname);
  		ASSERT(0);
  		return XFS_ERROR(EINVAL);
  	}
  	agino = XFS_INO_TO_AGINO(mp, inode);
  	if (inode != XFS_AGINO_TO_INO(mp, agno, agino))  {
  		cmn_err(CE_WARN,

  			"xfs_difree: inode != XFS_AGINO_TO_INO() "
  			"(%llu != %llu) on %s.  Returning EINVAL.",
  			(unsigned long long)inode,
  			(unsigned long long)XFS_AGINO_TO_INO(mp, agno, agino),
  			mp->m_fsname);

  		ASSERT(0);
  		return XFS_ERROR(EINVAL);
  	}
  	agbno = XFS_AGINO_TO_AGBNO(mp, agino);
  	if (agbno >= mp->m_sb.sb_agblocks)  {
  		cmn_err(CE_WARN,
  			"xfs_difree: agbno >= mp->m_sb.sb_agblocks (%d >= %d) on %s.  Returning EINVAL.",
  			agbno, mp->m_sb.sb_agblocks, mp->m_fsname);
  		ASSERT(0);
  		return XFS_ERROR(EINVAL);
  	}
  	/*
  	 * Get the allocation group header.
  	 */
  	down_read(&mp->m_peraglock);
  	error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
  	up_read(&mp->m_peraglock);
  	if (error) {
  		cmn_err(CE_WARN,
  			"xfs_difree: xfs_ialloc_read_agi() returned an error %d on %s.  Returning error.",
  			error, mp->m_fsname);
  		return error;
  	}
  	agi = XFS_BUF_TO_AGI(agbp);

  	ASSERT(be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC);
  	ASSERT(agbno < be32_to_cpu(agi->agi_length));

  	/*
  	 * Initialize the cursor.
  	 */
  	cur = xfs_btree_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_INO,
  		(xfs_inode_t *)0, 0);
  #ifdef DEBUG
  	if (cur->bc_nlevels == 1) {
  		int freecount = 0;
  
  		if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
  			goto error0;
  		do {
  			if ((error = xfs_inobt_get_rec(cur, &rec.ir_startino,
  					&rec.ir_freecount, &rec.ir_free, &i)))
  				goto error0;
  			if (i) {
  				freecount += rec.ir_freecount;
  				if ((error = xfs_inobt_increment(cur, 0, &i)))
  					goto error0;
  			}
  		} while (i == 1);

  		ASSERT(freecount == be32_to_cpu(agi->agi_freecount) ||

  		       XFS_FORCED_SHUTDOWN(mp));
  	}
  #endif
  	/*
  	 * Look for the entry describing this inode.
  	 */
  	if ((error = xfs_inobt_lookup_le(cur, agino, 0, 0, &i))) {
  		cmn_err(CE_WARN,
  			"xfs_difree: xfs_inobt_lookup_le returned()  an error %d on %s.  Returning error.",
  			error, mp->m_fsname);
  		goto error0;
  	}
  	XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
  	if ((error = xfs_inobt_get_rec(cur, &rec.ir_startino, &rec.ir_freecount,
  			&rec.ir_free, &i))) {
  		cmn_err(CE_WARN,
  			"xfs_difree: xfs_inobt_get_rec()  returned an error %d on %s.  Returning error.",
  			error, mp->m_fsname);
  		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(!XFS_INOBT_IS_FREE(&rec, off));
  	/*
  	 * Mark the inode free & increment the count.
  	 */
  	XFS_INOBT_SET_FREE(&rec, off);
  	rec.ir_freecount++;
  
  	/*

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

  	 */
  	if ((mp->m_flags & XFS_MOUNT_IDELETE) &&
  	    (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(&agi->agi_count, -ilen);
  		be32_add(&agi->agi_freecount, -(ilen - 1));

  		xfs_ialloc_log_agi(tp, agbp, XFS_AGI_COUNT | XFS_AGI_FREECOUNT);
  		down_read(&mp->m_peraglock);
  		mp->m_perag[agno].pagi_freecount -= ilen - 1;
  		up_read(&mp->m_peraglock);
  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_ICOUNT, -ilen);
  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -(ilen - 1));
  
  		if ((error = xfs_inobt_delete(cur, &i))) {
  			cmn_err(CE_WARN, "xfs_difree: xfs_inobt_delete returned an error %d on %s.
  ",
  				error, mp->m_fsname);
  			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;
  
  		if ((error = xfs_inobt_update(cur, rec.ir_startino, rec.ir_freecount, rec.ir_free))) {
  			cmn_err(CE_WARN,
  				"xfs_difree: xfs_inobt_update()  returned an error %d on %s.  Returning error.",
  				error, mp->m_fsname);
  			goto error0;
  		}
  		/* 
  		 * Change the inode free counts and log the ag/sb changes.
  		 */

  		be32_add(&agi->agi_freecount, 1);

  		xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
  		down_read(&mp->m_peraglock);
  		mp->m_perag[agno].pagi_freecount++;
  		up_read(&mp->m_peraglock);
  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, 1);
  	}
  
  #ifdef DEBUG
  	if (cur->bc_nlevels == 1) {
  		int freecount = 0;
  
  		if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
  			goto error0;
  		do {
  			if ((error = xfs_inobt_get_rec(cur,
  					&rec.ir_startino,
  					&rec.ir_freecount,
  					&rec.ir_free, &i)))
  				goto error0;
  			if (i) {
  				freecount += rec.ir_freecount;
  				if ((error = xfs_inobt_increment(cur, 0, &i)))
  					goto error0;
  			}
  		} while (i == 1);

  		ASSERT(freecount == be32_to_cpu(agi->agi_freecount) ||

  		       XFS_FORCED_SHUTDOWN(mp));
  	}
  #endif
  	xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  	return 0;
  
  error0:
  	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  	return error;
  }
  
  /*
   * Return the location of the inode in bno/off, for mapping it into a buffer.
   */
  /*ARGSUSED*/
  int
  xfs_dilocate(
  	xfs_mount_t	*mp,	/* file system mount structure */
  	xfs_trans_t	*tp,	/* transaction pointer */
  	xfs_ino_t	ino,	/* inode to locate */
  	xfs_fsblock_t	*bno,	/* output: block containing inode */
  	int		*len,	/* output: num blocks in inode cluster */
  	int		*off,	/* output: index in block of inode */
  	uint		flags)	/* flags concerning inode lookup */
  {
  	xfs_agblock_t	agbno;	/* block number of inode in the alloc group */
  	xfs_buf_t	*agbp;	/* agi buffer */
  	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_agino_t	chunk_agino;	/* first agino in inode chunk */
  	__int32_t	chunk_cnt;	/* count of free inodes in chunk */
  	xfs_inofree_t	chunk_free;	/* mask of free inodes in chunk */
  	xfs_agblock_t	cluster_agbno;	/* first block in inode cluster */
  	xfs_btree_cur_t	*cur;	/* inode btree cursor */
  	int		error;	/* error code */
  	int		i;	/* temp state */
  	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

  		/* no diagnostics for bulkstat, ino comes from userspace */
  		if (flags & XFS_IMAP_BULKSTAT)
  			return XFS_ERROR(EINVAL);

  		if (agno >= mp->m_sb.sb_agcount) {
  			xfs_fs_cmn_err(CE_ALERT, mp,
  					"xfs_dilocate: agno (%d) >= "
  					"mp->m_sb.sb_agcount (%d)",
  					agno,  mp->m_sb.sb_agcount);
  		}
  		if (agbno >= mp->m_sb.sb_agblocks) {
  			xfs_fs_cmn_err(CE_ALERT, mp,
  					"xfs_dilocate: agbno (0x%llx) >= "
  					"mp->m_sb.sb_agblocks (0x%lx)",
  					(unsigned long long) agbno,
  					(unsigned long) mp->m_sb.sb_agblocks);
  		}
  		if (ino != XFS_AGINO_TO_INO(mp, agno, agino)) {
  			xfs_fs_cmn_err(CE_ALERT, mp,
  					"xfs_dilocate: ino (0x%llx) != "
  					"XFS_AGINO_TO_INO(mp, agno, agino) "
  					"(0x%llx)",
  					ino, XFS_AGINO_TO_INO(mp, agno, agino));
  		}

  		xfs_stack_trace();

  #endif /* DEBUG */
  		return XFS_ERROR(EINVAL);
  	}
  	if ((mp->m_sb.sb_blocksize >= XFS_INODE_CLUSTER_SIZE(mp)) ||
  	    !(flags & XFS_IMAP_LOOKUP)) {
  		offset = XFS_INO_TO_OFFSET(mp, ino);
  		ASSERT(offset < mp->m_sb.sb_inopblock);
  		*bno = XFS_AGB_TO_FSB(mp, agno, agbno);
  		*off = offset;
  		*len = 1;
  		return 0;
  	}
  	blks_per_cluster = XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_blocklog;
  	if (*bno != NULLFSBLOCK) {
  		offset = XFS_INO_TO_OFFSET(mp, ino);
  		ASSERT(offset < mp->m_sb.sb_inopblock);
  		cluster_agbno = XFS_FSB_TO_AGBNO(mp, *bno);
  		*off = ((agbno - cluster_agbno) * mp->m_sb.sb_inopblock) +
  			offset;
  		*len = blks_per_cluster;
  		return 0;
  	}
  	if (mp->m_inoalign_mask) {
  		offset_agbno = agbno & mp->m_inoalign_mask;
  		chunk_agbno = agbno - offset_agbno;
  	} else {
  		down_read(&mp->m_peraglock);
  		error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
  		up_read(&mp->m_peraglock);
  		if (error) {
  #ifdef DEBUG
  			xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
  					"xfs_ialloc_read_agi() returned "
  					"error %d, agno %d",
  					error, agno);
  #endif /* DEBUG */
  			return error;
  		}
  		cur = xfs_btree_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_INO,
  			(xfs_inode_t *)0, 0);
  		if ((error = xfs_inobt_lookup_le(cur, agino, 0, 0, &i))) {
  #ifdef DEBUG
  			xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
  					"xfs_inobt_lookup_le() failed");
  #endif /* DEBUG */
  			goto error0;
  		}
  		if ((error = xfs_inobt_get_rec(cur, &chunk_agino, &chunk_cnt,
  				&chunk_free, &i))) {
  #ifdef DEBUG
  			xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
  					"xfs_inobt_get_rec() failed");
  #endif /* DEBUG */
  			goto error0;
  		}
  		if (i == 0) {
  #ifdef DEBUG
  			xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
  					"xfs_inobt_get_rec() failed");
  #endif /* DEBUG */
  			error = XFS_ERROR(EINVAL);
  		}
  		xfs_trans_brelse(tp, agbp);
  		xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  		if (error)
  			return error;
  		chunk_agbno = XFS_AGINO_TO_AGBNO(mp, chunk_agino);
  		offset_agbno = agbno - chunk_agbno;
  	}
  	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);
  	*bno = XFS_AGB_TO_FSB(mp, agno, cluster_agbno);
  	*off = offset;
  	*len = blks_per_cluster;
  	return 0;
  error0:
  	xfs_trans_brelse(tp, agbp);
  	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  	return error;
  }
  
  /*
   * 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(be32_to_cpu(agi->agi_magicnum) == 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);
  }
  
  /*
   * Read in the allocation group header (inode allocation section)
   */
  int
  xfs_ialloc_read_agi(
  	xfs_mount_t	*mp,		/* file system mount structure */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_agnumber_t	agno,		/* allocation group number */
  	xfs_buf_t	**bpp)		/* allocation group hdr buf */
  {
  	xfs_agi_t	*agi;		/* allocation group header */
  	int		agi_ok;		/* agi is consistent */
  	xfs_buf_t	*bp;		/* allocation group hdr buf */
  	xfs_perag_t	*pag;		/* per allocation group data */
  	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, &bp);
  	if (error)
  		return error;
  	ASSERT(bp && !XFS_BUF_GETERROR(bp));
  
  	/*
  	 * Validate the magic number of the agi block.
  	 */
  	agi = XFS_BUF_TO_AGI(bp);
  	agi_ok =

  		be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC &&
  		XFS_AGI_GOOD_VERSION(be32_to_cpu(agi->agi_versionnum));

  	if (unlikely(XFS_TEST_ERROR(!agi_ok, mp, XFS_ERRTAG_IALLOC_READ_AGI,
  			XFS_RANDOM_IALLOC_READ_AGI))) {
  		XFS_CORRUPTION_ERROR("xfs_ialloc_read_agi", XFS_ERRLEVEL_LOW,
  				     mp, agi);
  		xfs_trans_brelse(tp, bp);
  		return XFS_ERROR(EFSCORRUPTED);
  	}
  	pag = &mp->m_perag[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;
  	} else {
  		/*
  		 * 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));

  	}
  
  #ifdef DEBUG
  	{
  		int	i;
  
  		for (i = 0; i < XFS_AGI_UNLINKED_BUCKETS; i++)
  			ASSERT(agi->agi_unlinked[i]);
  	}
  #endif
  
  	XFS_BUF_SET_VTYPE_REF(bp, B_FS_AGI, XFS_AGI_REF);
  	*bpp = bp;
  	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;
  }