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File: [Development] / xfs-linux-nodel / xfs_ialloc.c (download)

Revision 1.201, Wed Sep 24 16:11:20 2008 UTC (9 years ago) by lachlan.longdrop.melbourne.sgi.com
Branch: MAIN
Changes since 1.200: +4 -8 lines

split up xfs_btree_init_cursor

xfs_btree_init_cursor contains close to little shared code for the different
btrees and will get even more non-common code in the future.  Split it up
into one routine per btree type.

Because xfs_btree_dup_cursor needs to call the init routine for a generic
btree cursor add a new btree operation vector that contains a dup_cursor
method that initializes a new cursor based on an existing one.

The btree operations vector is based on an idea and code from Dave Chinner
and will grow more entries later during this series.


Signed-off-by: Christoph Hellwig <hch@lst.de>
Merge of xfs-linux-melb:xfs-kern:32176a by kenmcd.

  split up xfs_btree_init_cursor

/*
 * 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.
 */
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;
}

/*
 * 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 */
	unsigned int	gen;

	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;

		/*
		 * 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 = 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
			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,
				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);
		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);
	/*
	 * 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;

	/*
	 * 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.
	 */
	gen = random32();
	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);
			free->di_core.di_magic = cpu_to_be16(XFS_DINODE_MAGIC);
			free->di_core.di_version = version;
			free->di_core.di_gen = cpu_to_be32(gen);
			free->di_next_unlinked = cpu_to_be32(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_cpu(&agi->agi_count, newlen);
	be32_add_cpu(&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_inobt_init_cursor(args.mp, tp, agbp, agno);
	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_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);
#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_cpu(&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_inobt_init_cursor(mp, tp, agbp, agno);
#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_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);
		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.\n",
				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_cpu(&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_inobt_init_cursor(mp, tp, agbp, agno);
		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;
}