text: /*
   *   Copyright (C) International Business Machines Corp., 2000-2004
   *
   *   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; either version 2 of the License, or
   *   (at your option) any later version.
   *
   *   This program is distributed in the hope that it will 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 to the Free Software
   *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
   */
  
  /*
   *	jfs_imap.c: inode allocation map manager
   *
   * Serialization:
   *   Each AG has a simple lock which is used to control the serialization of
   *	the AG level lists.  This lock should be taken first whenever an AG
   *	level list will be modified or accessed.
   *
   *   Each IAG is locked by obtaining the buffer for the IAG page.
   *
   *   There is also a inode lock for the inode map inode.  A read lock needs to
   *	be taken whenever an IAG is read from the map or the global level
   *	information is read.  A write lock needs to be taken whenever the global
   *	level information is modified or an atomic operation needs to be used.
   *
   *	If more than one IAG is read at one time, the read lock may not
   *	be given up until all of the IAG's are read.  Otherwise, a deadlock
   *	may occur when trying to obtain the read lock while another thread
   *	holding the read lock is waiting on the IAG already being held.
   *
   *   The control page of the inode map is read into memory by diMount().
   *	Thereafter it should only be modified in memory and then it will be
   *	written out when the filesystem is unmounted by diUnmount().
   */
  
  #include <linux/fs.h>
  #include <linux/buffer_head.h>
  #include <linux/pagemap.h>
  #include <linux/quotaops.h>
  #include <linux/slab.h>
  
  #include "jfs_incore.h"
  #include "jfs_inode.h"
  #include "jfs_filsys.h"
  #include "jfs_dinode.h"
  #include "jfs_dmap.h"
  #include "jfs_imap.h"
  #include "jfs_metapage.h"
  #include "jfs_superblock.h"
  #include "jfs_debug.h"
  
  /*
   * imap locks
   */
  /* iag free list lock */
  #define IAGFREE_LOCK_INIT(imap)		mutex_init(&imap->im_freelock)
  #define IAGFREE_LOCK(imap)		mutex_lock(&imap->im_freelock)
  #define IAGFREE_UNLOCK(imap)		mutex_unlock(&imap->im_freelock)
  
  /* per ag iag list locks */
  #define AG_LOCK_INIT(imap,index)	mutex_init(&(imap->im_aglock[index]))
  #define AG_LOCK(imap,agno)		mutex_lock(&imap->im_aglock[agno])
  #define AG_UNLOCK(imap,agno)		mutex_unlock(&imap->im_aglock[agno])
  
  /*
   * forward references
   */
  static int diAllocAG(struct inomap *, int, bool, struct inode *);
  static int diAllocAny(struct inomap *, int, bool, struct inode *);
  static int diAllocBit(struct inomap *, struct iag *, int);
  static int diAllocExt(struct inomap *, int, struct inode *);
  static int diAllocIno(struct inomap *, int, struct inode *);
  static int diFindFree(u32, int);
  static int diNewExt(struct inomap *, struct iag *, int);
  static int diNewIAG(struct inomap *, int *, int, struct metapage **);
  static void duplicateIXtree(struct super_block *, s64, int, s64 *);
  
  static int diIAGRead(struct inomap * imap, int, struct metapage **);
  static int copy_from_dinode(struct dinode *, struct inode *);
  static void copy_to_dinode(struct dinode *, struct inode *);
  
  /*
   * NAME:	diMount()
   *
   * FUNCTION:	initialize the incore inode map control structures for
   *		a fileset or aggregate init time.
   *
   *		the inode map's control structure (dinomap) is
   *		brought in from disk and placed in virtual memory.
   *
   * PARAMETERS:
   *	ipimap	- pointer to inode map inode for the aggregate or fileset.
   *
   * RETURN VALUES:
   *	0	- success
   *	-ENOMEM	- insufficient free virtual memory.
   *	-EIO	- i/o error.
   */
  int diMount(struct inode *ipimap)
  {
  	struct inomap *imap;
  	struct metapage *mp;
  	int index;
  	struct dinomap_disk *dinom_le;
  
  	/*
  	 * allocate/initialize the in-memory inode map control structure
  	 */
  	/* allocate the in-memory inode map control structure. */
  	imap = kmalloc(sizeof(struct inomap), GFP_KERNEL);
  	if (imap == NULL) {
  		jfs_err("diMount: kmalloc returned NULL!");
  		return -ENOMEM;
  	}
  
  	/* read the on-disk inode map control structure. */
  
  	mp = read_metapage(ipimap,
  			   IMAPBLKNO << JFS_SBI(ipimap->i_sb)->l2nbperpage,
  			   PSIZE, 0);
  	if (mp == NULL) {
  		kfree(imap);
  		return -EIO;
  	}
  
  	/* copy the on-disk version to the in-memory version. */
  	dinom_le = (struct dinomap_disk *) mp->data;
  	imap->im_freeiag = le32_to_cpu(dinom_le->in_freeiag);
  	imap->im_nextiag = le32_to_cpu(dinom_le->in_nextiag);
  	atomic_set(&imap->im_numinos, le32_to_cpu(dinom_le->in_numinos));
  	atomic_set(&imap->im_numfree, le32_to_cpu(dinom_le->in_numfree));
  	imap->im_nbperiext = le32_to_cpu(dinom_le->in_nbperiext);
  	imap->im_l2nbperiext = le32_to_cpu(dinom_le->in_l2nbperiext);
  	for (index = 0; index < MAXAG; index++) {
  		imap->im_agctl[index].inofree =
  		    le32_to_cpu(dinom_le->in_agctl[index].inofree);
  		imap->im_agctl[index].extfree =
  		    le32_to_cpu(dinom_le->in_agctl[index].extfree);
  		imap->im_agctl[index].numinos =
  		    le32_to_cpu(dinom_le->in_agctl[index].numinos);
  		imap->im_agctl[index].numfree =
  		    le32_to_cpu(dinom_le->in_agctl[index].numfree);
  	}
  
  	/* release the buffer. */
  	release_metapage(mp);
  
  	/*
  	 * allocate/initialize inode allocation map locks
  	 */
  	/* allocate and init iag free list lock */
  	IAGFREE_LOCK_INIT(imap);
  
  	/* allocate and init ag list locks */
  	for (index = 0; index < MAXAG; index++) {
  		AG_LOCK_INIT(imap, index);
  	}
  
  	/* bind the inode map inode and inode map control structure
  	 * to each other.
  	 */
  	imap->im_ipimap = ipimap;
  	JFS_IP(ipimap)->i_imap = imap;
  
  	return (0);
  }
  
  
  /*
   * NAME:	diUnmount()
   *
   * FUNCTION:	write to disk the incore inode map control structures for
   *		a fileset or aggregate at unmount time.
   *
   * PARAMETERS:
   *	ipimap	- pointer to inode map inode for the aggregate or fileset.
   *
   * RETURN VALUES:
   *	0	- success
   *	-ENOMEM	- insufficient free virtual memory.
   *	-EIO	- i/o error.
   */
  int diUnmount(struct inode *ipimap, int mounterror)
  {
  	struct inomap *imap = JFS_IP(ipimap)->i_imap;
  
  	/*
  	 * update the on-disk inode map control structure
  	 */
  
  	if (!(mounterror || isReadOnly(ipimap)))
  		diSync(ipimap);
  
  	/*
  	 * Invalidate the page cache buffers
  	 */
  	truncate_inode_pages(ipimap->i_mapping, 0);
  
  	/*
  	 * free in-memory control structure
  	 */
  	kfree(imap);
  
  	return (0);
  }
  
  
  /*
   *	diSync()
   */
  int diSync(struct inode *ipimap)
  {
  	struct dinomap_disk *dinom_le;
  	struct inomap *imp = JFS_IP(ipimap)->i_imap;
  	struct metapage *mp;
  	int index;
  
  	/*
  	 * write imap global conrol page
  	 */
  	/* read the on-disk inode map control structure */
  	mp = get_metapage(ipimap,
  			  IMAPBLKNO << JFS_SBI(ipimap->i_sb)->l2nbperpage,
  			  PSIZE, 0);
  	if (mp == NULL) {
  		jfs_err("diSync: get_metapage failed!");
  		return -EIO;
  	}
  
  	/* copy the in-memory version to the on-disk version */
  	dinom_le = (struct dinomap_disk *) mp->data;
  	dinom_le->in_freeiag = cpu_to_le32(imp->im_freeiag);
  	dinom_le->in_nextiag = cpu_to_le32(imp->im_nextiag);
  	dinom_le->in_numinos = cpu_to_le32(atomic_read(&imp->im_numinos));
  	dinom_le->in_numfree = cpu_to_le32(atomic_read(&imp->im_numfree));
  	dinom_le->in_nbperiext = cpu_to_le32(imp->im_nbperiext);
  	dinom_le->in_l2nbperiext = cpu_to_le32(imp->im_l2nbperiext);
  	for (index = 0; index < MAXAG; index++) {
  		dinom_le->in_agctl[index].inofree =
  		    cpu_to_le32(imp->im_agctl[index].inofree);
  		dinom_le->in_agctl[index].extfree =
  		    cpu_to_le32(imp->im_agctl[index].extfree);
  		dinom_le->in_agctl[index].numinos =
  		    cpu_to_le32(imp->im_agctl[index].numinos);
  		dinom_le->in_agctl[index].numfree =
  		    cpu_to_le32(imp->im_agctl[index].numfree);
  	}
  
  	/* write out the control structure */
  	write_metapage(mp);
  
  	/*
  	 * write out dirty pages of imap
  	 */
  	filemap_write_and_wait(ipimap->i_mapping);
  
  	diWriteSpecial(ipimap, 0);
  
  	return (0);
  }
  
  
  /*
   * NAME:	diRead()
   *
   * FUNCTION:	initialize an incore inode from disk.
   *
   *		on entry, the specifed incore inode should itself
   *		specify the disk inode number corresponding to the
   *		incore inode (i.e. i_number should be initialized).
   *
   *		this routine handles incore inode initialization for
   *		both "special" and "regular" inodes.  special inodes
   *		are those required early in the mount process and
   *		require special handling since much of the file system
   *		is not yet initialized.  these "special" inodes are
   *		identified by a NULL inode map inode pointer and are
   *		actually initialized by a call to diReadSpecial().
   *
   *		for regular inodes, the iag describing the disk inode
   *		is read from disk to determine the inode extent address
   *		for the disk inode.  with the inode extent address in
   *		hand, the page of the extent that contains the disk
   *		inode is read and the disk inode is copied to the
   *		incore inode.
   *
   * PARAMETERS:
   *	ip	-  pointer to incore inode to be initialized from disk.
   *
   * RETURN VALUES:
   *	0	- success
   *	-EIO	- i/o error.
   *	-ENOMEM	- insufficient memory
   *
   */
  int diRead(struct inode *ip)
  {
  	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
  	int iagno, ino, extno, rc;
  	struct inode *ipimap;
  	struct dinode *dp;
  	struct iag *iagp;
  	struct metapage *mp;
  	s64 blkno, agstart;
  	struct inomap *imap;
  	int block_offset;
  	int inodes_left;
  	unsigned long pageno;
  	int rel_inode;
  
  	jfs_info("diRead: ino = %ld", ip->i_ino);
  
  	ipimap = sbi->ipimap;
  	JFS_IP(ip)->ipimap = ipimap;
  
  	/* determine the iag number for this inode (number) */
  	iagno = INOTOIAG(ip->i_ino);
  
  	/* read the iag */
  	imap = JFS_IP(ipimap)->i_imap;
  	IREAD_LOCK(ipimap, RDWRLOCK_IMAP);
  	rc = diIAGRead(imap, iagno, &mp);
  	IREAD_UNLOCK(ipimap);
  	if (rc) {
  		jfs_err("diRead: diIAGRead returned %d", rc);
  		return (rc);
  	}
  
  	iagp = (struct iag *) mp->data;
  
  	/* determine inode extent that holds the disk inode */
  	ino = ip->i_ino & (INOSPERIAG - 1);
  	extno = ino >> L2INOSPEREXT;
  
  	if ((lengthPXD(&iagp->inoext[extno]) != imap->im_nbperiext) ||
  	    (addressPXD(&iagp->inoext[extno]) == 0)) {
  		release_metapage(mp);
  		return -ESTALE;
  	}
  
  	/* get disk block number of the page within the inode extent
  	 * that holds the disk inode.
  	 */
  	blkno = INOPBLK(&iagp->inoext[extno], ino, sbi->l2nbperpage);
  
  	/* get the ag for the iag */
  	agstart = le64_to_cpu(iagp->agstart);
  
  	release_metapage(mp);
  
  	rel_inode = (ino & (INOSPERPAGE - 1));
  	pageno = blkno >> sbi->l2nbperpage;
  
  	if ((block_offset = ((u32) blkno & (sbi->nbperpage - 1)))) {
  		/*
  		 * OS/2 didn't always align inode extents on page boundaries
  		 */
  		inodes_left =
  		     (sbi->nbperpage - block_offset) << sbi->l2niperblk;
  
  		if (rel_inode < inodes_left)
  			rel_inode += block_offset << sbi->l2niperblk;
  		else {
  			pageno += 1;
  			rel_inode -= inodes_left;
  		}
  	}
  
  	/* read the page of disk inode */
  	mp = read_metapage(ipimap, pageno << sbi->l2nbperpage, PSIZE, 1);
  	if (!mp) {
  		jfs_err("diRead: read_metapage failed");
  		return -EIO;
  	}
  
  	/* locate the disk inode requested */
  	dp = (struct dinode *) mp->data;
  	dp += rel_inode;
  
  	if (ip->i_ino != le32_to_cpu(dp->di_number)) {
  		jfs_error(ip->i_sb, "diRead: i_ino != di_number");
  		rc = -EIO;
  	} else if (le32_to_cpu(dp->di_nlink) == 0)
  		rc = -ESTALE;
  	else
  		/* copy the disk inode to the in-memory inode */
  		rc = copy_from_dinode(dp, ip);
  
  	release_metapage(mp);
  
  	/* set the ag for the inode */
  	JFS_IP(ip)->agstart = agstart;
  	JFS_IP(ip)->active_ag = -1;
  
  	return (rc);
  }
  
  
  /*
   * NAME:	diReadSpecial()
   *
   * FUNCTION:	initialize a 'special' inode from disk.
   *
   *		this routines handles aggregate level inodes.  The
   *		inode cache cannot differentiate between the
   *		aggregate inodes and the filesystem inodes, so we
   *		handle these here.  We don't actually use the aggregate
   *		inode map, since these inodes are at a fixed location
   *		and in some cases the aggregate inode map isn't initialized
   *		yet.
   *
   * PARAMETERS:
   *	sb - filesystem superblock
   *	inum - aggregate inode number
   *	secondary - 1 if secondary aggregate inode table
   *
   * RETURN VALUES:
   *	new inode	- success
   *	NULL		- i/o error.
   */
  struct inode *diReadSpecial(struct super_block *sb, ino_t inum, int secondary)
  {
  	struct jfs_sb_info *sbi = JFS_SBI(sb);
  	uint address;
  	struct dinode *dp;
  	struct inode *ip;
  	struct metapage *mp;
  
  	ip = new_inode(sb);
  	if (ip == NULL) {
  		jfs_err("diReadSpecial: new_inode returned NULL!");
  		return ip;
  	}
  
  	if (secondary) {
  		address = addressPXD(&sbi->ait2) >> sbi->l2nbperpage;
  		JFS_IP(ip)->ipimap = sbi->ipaimap2;
  	} else {
  		address = AITBL_OFF >> L2PSIZE;
  		JFS_IP(ip)->ipimap = sbi->ipaimap;
  	}
  
  	ASSERT(inum < INOSPEREXT);
  
  	ip->i_ino = inum;
  
  	address += inum >> 3;	/* 8 inodes per 4K page */
  
  	/* read the page of fixed disk inode (AIT) in raw mode */
  	mp = read_metapage(ip, address << sbi->l2nbperpage, PSIZE, 1);
  	if (mp == NULL) {
  		ip->i_nlink = 1;	/* Don't want iput() deleting it */
  		iput(ip);
  		return (NULL);
  	}
  
  	/* get the pointer to the disk inode of interest */
  	dp = (struct dinode *) (mp->data);
  	dp += inum % 8;		/* 8 inodes per 4K page */
  
  	/* copy on-disk inode to in-memory inode */
  	if ((copy_from_dinode(dp, ip)) != 0) {
  		/* handle bad return by returning NULL for ip */
  		ip->i_nlink = 1;	/* Don't want iput() deleting it */
  		iput(ip);
  		/* release the page */
  		release_metapage(mp);
  		return (NULL);
  
  	}
  
  	ip->i_mapping->a_ops = &jfs_metapage_aops;
  	mapping_set_gfp_mask(ip->i_mapping, GFP_NOFS);
  
  	/* Allocations to metadata inodes should not affect quotas */
  	ip->i_flags |= S_NOQUOTA;
  
  	if ((inum == FILESYSTEM_I) && (JFS_IP(ip)->ipimap == sbi->ipaimap)) {
  		sbi->gengen = le32_to_cpu(dp->di_gengen);
  		sbi->inostamp = le32_to_cpu(dp->di_inostamp);
  	}
  
  	/* release the page */
  	release_metapage(mp);
  
  	/*
  	 * __mark_inode_dirty expects inodes to be hashed.  Since we don't
  	 * want special inodes in the fileset inode space, we make them
  	 * appear hashed, but do not put on any lists.  hlist_del()
  	 * will work fine and require no locking.
  	 */
  	hlist_add_fake(&ip->i_hash);
  
  	return (ip);
  }
  
  /*
   * NAME:	diWriteSpecial()
   *
   * FUNCTION:	Write the special inode to disk
   *
   * PARAMETERS:
   *	ip - special inode
   *	secondary - 1 if secondary aggregate inode table
   *
   * RETURN VALUES: none
   */
  
  void diWriteSpecial(struct inode *ip, int secondary)
  {
  	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
  	uint address;
  	struct dinode *dp;
  	ino_t inum = ip->i_ino;
  	struct metapage *mp;
  
  	if (secondary)
  		address = addressPXD(&sbi->ait2) >> sbi->l2nbperpage;
  	else
  		address = AITBL_OFF >> L2PSIZE;
  
  	ASSERT(inum < INOSPEREXT);
  
  	address += inum >> 3;	/* 8 inodes per 4K page */
  
  	/* read the page of fixed disk inode (AIT) in raw mode */
  	mp = read_metapage(ip, address << sbi->l2nbperpage, PSIZE, 1);
  	if (mp == NULL) {
  		jfs_err("diWriteSpecial: failed to read aggregate inode "
  			"extent!");
  		return;
  	}
  
  	/* get the pointer to the disk inode of interest */
  	dp = (struct dinode *) (mp->data);
  	dp += inum % 8;		/* 8 inodes per 4K page */
  
  	/* copy on-disk inode to in-memory inode */
  	copy_to_dinode(dp, ip);
  	memcpy(&dp->di_xtroot, &JFS_IP(ip)->i_xtroot, 288);
  
  	if (inum == FILESYSTEM_I)
  		dp->di_gengen = cpu_to_le32(sbi->gengen);
  
  	/* write the page */
  	write_metapage(mp);
  }
  
  /*
   * NAME:	diFreeSpecial()
   *
   * FUNCTION:	Free allocated space for special inode
   */
  void diFreeSpecial(struct inode *ip)
  {
  	if (ip == NULL) {
  		jfs_err("diFreeSpecial called with NULL ip!");
  		return;
  	}
  	filemap_write_and_wait(ip->i_mapping);
  	truncate_inode_pages(ip->i_mapping, 0);
  	iput(ip);
  }
  
  
  
  /*
   * NAME:	diWrite()
   *
   * FUNCTION:	write the on-disk inode portion of the in-memory inode
   *		to its corresponding on-disk inode.
   *
   *		on entry, the specifed incore inode should itself
   *		specify the disk inode number corresponding to the
   *		incore inode (i.e. i_number should be initialized).
   *
   *		the inode contains the inode extent address for the disk
   *		inode.  with the inode extent address in hand, the
   *		page of the extent that contains the disk inode is
   *		read and the disk inode portion of the incore inode
   *		is copied to the disk inode.
   *
   * PARAMETERS:
   *	tid -  transacation id
   *	ip  -  pointer to incore inode to be written to the inode extent.
   *
   * RETURN VALUES:
   *	0	- success
   *	-EIO	- i/o error.
   */
  int diWrite(tid_t tid, struct inode *ip)
  {
  	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
  	struct jfs_inode_info *jfs_ip = JFS_IP(ip);
  	int rc = 0;
  	s32 ino;
  	struct dinode *dp;
  	s64 blkno;
  	int block_offset;
  	int inodes_left;
  	struct metapage *mp;
  	unsigned long pageno;
  	int rel_inode;
  	int dioffset;
  	struct inode *ipimap;
  	uint type;
  	lid_t lid;
  	struct tlock *ditlck, *tlck;
  	struct linelock *dilinelock, *ilinelock;
  	struct lv *lv;
  	int n;
  
  	ipimap = jfs_ip->ipimap;
  
  	ino = ip->i_ino & (INOSPERIAG - 1);
  
  	if (!addressPXD(&(jfs_ip->ixpxd)) ||
  	    (lengthPXD(&(jfs_ip->ixpxd)) !=
  	     JFS_IP(ipimap)->i_imap->im_nbperiext)) {
  		jfs_error(ip->i_sb, "diWrite: ixpxd invalid");
  		return -EIO;
  	}
  
  	/*
  	 * read the page of disk inode containing the specified inode:
  	 */
  	/* compute the block address of the page */
  	blkno = INOPBLK(&(jfs_ip->ixpxd), ino, sbi->l2nbperpage);
  
  	rel_inode = (ino & (INOSPERPAGE - 1));
  	pageno = blkno >> sbi->l2nbperpage;
  
  	if ((block_offset = ((u32) blkno & (sbi->nbperpage - 1)))) {
  		/*
  		 * OS/2 didn't always align inode extents on page boundaries
  		 */
  		inodes_left =
  		    (sbi->nbperpage - block_offset) << sbi->l2niperblk;
  
  		if (rel_inode < inodes_left)
  			rel_inode += block_offset << sbi->l2niperblk;
  		else {
  			pageno += 1;
  			rel_inode -= inodes_left;
  		}
  	}
  	/* read the page of disk inode */
        retry:
  	mp = read_metapage(ipimap, pageno << sbi->l2nbperpage, PSIZE, 1);
  	if (!mp)
  		return -EIO;
  
  	/* get the pointer to the disk inode */
  	dp = (struct dinode *) mp->data;
  	dp += rel_inode;
  
  	dioffset = (ino & (INOSPERPAGE - 1)) << L2DISIZE;
  
  	/*
  	 * acquire transaction lock on the on-disk inode;
  	 * N.B. tlock is acquired on ipimap not ip;
  	 */
  	if ((ditlck =
  	     txLock(tid, ipimap, mp, tlckINODE | tlckENTRY)) == NULL)
  		goto retry;
  	dilinelock = (struct linelock *) & ditlck->lock;
  
  	/*
  	 * copy btree root from in-memory inode to on-disk inode
  	 *
  	 * (tlock is taken from inline B+-tree root in in-memory
  	 * inode when the B+-tree root is updated, which is pointed
  	 * by jfs_ip->blid as well as being on tx tlock list)
  	 *
  	 * further processing of btree root is based on the copy
  	 * in in-memory inode, where txLog() will log from, and,
  	 * for xtree root, txUpdateMap() will update map and reset
  	 * XAD_NEW bit;
  	 */
  
  	if (S_ISDIR(ip->i_mode) && (lid = jfs_ip->xtlid)) {
  		/*
  		 * This is the special xtree inside the directory for storing
  		 * the directory table
  		 */
  		xtpage_t *p, *xp;
  		xad_t *xad;
  
  		jfs_ip->xtlid = 0;
  		tlck = lid_to_tlock(lid);
  		assert(tlck->type & tlckXTREE);
  		tlck->type |= tlckBTROOT;
  		tlck->mp = mp;
  		ilinelock = (struct linelock *) & tlck->lock;
  
  		/*
  		 * copy xtree root from inode to dinode:
  		 */
  		p = &jfs_ip->i_xtroot;
  		xp = (xtpage_t *) &dp->di_dirtable;
  		lv = ilinelock->lv;
  		for (n = 0; n < ilinelock->index; n++, lv++) {
  			memcpy(&xp->xad[lv->offset], &p->xad[lv->offset],
  			       lv->length << L2XTSLOTSIZE);
  		}
  
  		/* reset on-disk (metadata page) xtree XAD_NEW bit */
  		xad = &xp->xad[XTENTRYSTART];
  		for (n = XTENTRYSTART;
  		     n < le16_to_cpu(xp->header.nextindex); n++, xad++)
  			if (xad->flag & (XAD_NEW | XAD_EXTENDED))
  				xad->flag &= ~(XAD_NEW | XAD_EXTENDED);
  	}
  
  	if ((lid = jfs_ip->blid) == 0)
  		goto inlineData;
  	jfs_ip->blid = 0;
  
  	tlck = lid_to_tlock(lid);
  	type = tlck->type;
  	tlck->type |= tlckBTROOT;
  	tlck->mp = mp;
  	ilinelock = (struct linelock *) & tlck->lock;
  
  	/*
  	 *	regular file: 16 byte (XAD slot) granularity
  	 */
  	if (type & tlckXTREE) {
  		xtpage_t *p, *xp;
  		xad_t *xad;
  
  		/*
  		 * copy xtree root from inode to dinode:
  		 */
  		p = &jfs_ip->i_xtroot;
  		xp = &dp->di_xtroot;
  		lv = ilinelock->lv;
  		for (n = 0; n < ilinelock->index; n++, lv++) {
  			memcpy(&xp->xad[lv->offset], &p->xad[lv->offset],
  			       lv->length << L2XTSLOTSIZE);
  		}
  
  		/* reset on-disk (metadata page) xtree XAD_NEW bit */
  		xad = &xp->xad[XTENTRYSTART];
  		for (n = XTENTRYSTART;
  		     n < le16_to_cpu(xp->header.nextindex); n++, xad++)
  			if (xad->flag & (XAD_NEW | XAD_EXTENDED))
  				xad->flag &= ~(XAD_NEW | XAD_EXTENDED);
  	}
  	/*
  	 *	directory: 32 byte (directory entry slot) granularity
  	 */
  	else if (type & tlckDTREE) {
  		dtpage_t *p, *xp;
  
  		/*
  		 * copy dtree root from inode to dinode:
  		 */
  		p = (dtpage_t *) &jfs_ip->i_dtroot;
  		xp = (dtpage_t *) & dp->di_dtroot;
  		lv = ilinelock->lv;
  		for (n = 0; n < ilinelock->index; n++, lv++) {
  			memcpy(&xp->slot[lv->offset], &p->slot[lv->offset],
  			       lv->length << L2DTSLOTSIZE);
  		}
  	} else {
  		jfs_err("diWrite: UFO tlock");
  	}
  
        inlineData:
  	/*
  	 * copy inline symlink from in-memory inode to on-disk inode
  	 */
  	if (S_ISLNK(ip->i_mode) && ip->i_size < IDATASIZE) {
  		lv = & dilinelock->lv[dilinelock->index];
  		lv->offset = (dioffset + 2 * 128) >> L2INODESLOTSIZE;
  		lv->length = 2;
  		memcpy(&dp->di_fastsymlink, jfs_ip->i_inline, IDATASIZE);
  		dilinelock->index++;
  	}
  	/*
  	 * copy inline data from in-memory inode to on-disk inode:
  	 * 128 byte slot granularity
  	 */
  	if (test_cflag(COMMIT_Inlineea, ip)) {
  		lv = & dilinelock->lv[dilinelock->index];
  		lv->offset = (dioffset + 3 * 128) >> L2INODESLOTSIZE;
  		lv->length = 1;
  		memcpy(&dp->di_inlineea, jfs_ip->i_inline_ea, INODESLOTSIZE);
  		dilinelock->index++;
  
  		clear_cflag(COMMIT_Inlineea, ip);
  	}
  
  	/*
  	 *	lock/copy inode base: 128 byte slot granularity
  	 */
  	lv = & dilinelock->lv[dilinelock->index];
  	lv->offset = dioffset >> L2INODESLOTSIZE;
  	copy_to_dinode(dp, ip);
  	if (test_and_clear_cflag(COMMIT_Dirtable, ip)) {
  		lv->length = 2;
  		memcpy(&dp->di_dirtable, &jfs_ip->i_dirtable, 96);
  	} else
  		lv->length = 1;
  	dilinelock->index++;
  
  	/* release the buffer holding the updated on-disk inode.
  	 * the buffer will be later written by commit processing.
  	 */
  	write_metapage(mp);
  
  	return (rc);
  }
  
  
  /*
   * NAME:	diFree(ip)
   *
   * FUNCTION:	free a specified inode from the inode working map
   *		for a fileset or aggregate.
   *
   *		if the inode to be freed represents the first (only)
   *		free inode within the iag, the iag will be placed on
   *		the ag free inode list.
   *
   *		freeing the inode will cause the inode extent to be
   *		freed if the inode is the only allocated inode within
   *		the extent.  in this case all the disk resource backing
   *		up the inode extent will be freed. in addition, the iag
   *		will be placed on the ag extent free list if the extent
   *		is the first free extent in the iag.  if freeing the
   *		extent also means that no free inodes will exist for
   *		the iag, the iag will also be removed from the ag free
   *		inode list.
   *
   *		the iag describing the inode will be freed if the extent
   *		is to be freed and it is the only backed extent within
   *		the iag.  in this case, the iag will be removed from the
   *		ag free extent list and ag free inode list and placed on
   *		the inode map's free iag list.
   *
   *		a careful update approach is used to provide consistency
   *		in the face of updates to multiple buffers.  under this
   *		approach, all required buffers are obtained before making
   *		any updates and are held until all updates are complete.
   *
   * PARAMETERS:
   *	ip	- inode to be freed.
   *
   * RETURN VALUES:
   *	0	- success
   *	-EIO	- i/o error.
   */
  int diFree(struct inode *ip)
  {
  	int rc;
  	ino_t inum = ip->i_ino;
  	struct iag *iagp, *aiagp, *biagp, *ciagp, *diagp;
  	struct metapage *mp, *amp, *bmp, *cmp, *dmp;
  	int iagno, ino, extno, bitno, sword, agno;
  	int back, fwd;
  	u32 bitmap, mask;
  	struct inode *ipimap = JFS_SBI(ip->i_sb)->ipimap;
  	struct inomap *imap = JFS_IP(ipimap)->i_imap;
  	pxd_t freepxd;
  	tid_t tid;
  	struct inode *iplist[3];
  	struct tlock *tlck;
  	struct pxd_lock *pxdlock;
  
  	/*
  	 * This is just to suppress compiler warnings.  The same logic that
  	 * references these variables is used to initialize them.
  	 */
  	aiagp = biagp = ciagp = diagp = NULL;
  
  	/* get the iag number containing the inode.
  	 */
  	iagno = INOTOIAG(inum);
  
  	/* make sure that the iag is contained within
  	 * the map.
  	 */
  	if (iagno >= imap->im_nextiag) {
  		print_hex_dump(KERN_ERR, "imap: ", DUMP_PREFIX_ADDRESS, 16, 4,
  			       imap, 32, 0);
  		jfs_error(ip->i_sb,
  			  "diFree: inum = %d, iagno = %d, nextiag = %d",
  			  (uint) inum, iagno, imap->im_nextiag);
  		return -EIO;
  	}
  
  	/* get the allocation group for this ino.
  	 */
  	agno = BLKTOAG(JFS_IP(ip)->agstart, JFS_SBI(ip->i_sb));
  
  	/* Lock the AG specific inode map information
  	 */
  	AG_LOCK(imap, agno);
  
  	/* Obtain read lock in imap inode.  Don't release it until we have
  	 * read all of the IAG's that we are going to.
  	 */
  	IREAD_LOCK(ipimap, RDWRLOCK_IMAP);
  
  	/* read the iag.
  	 */
  	if ((rc = diIAGRead(imap, iagno, &mp))) {
  		IREAD_UNLOCK(ipimap);
  		AG_UNLOCK(imap, agno);
  		return (rc);
  	}
  	iagp = (struct iag *) mp->data;
  
  	/* get the inode number and extent number of the inode within
  	 * the iag and the inode number within the extent.
  	 */
  	ino = inum & (INOSPERIAG - 1);
  	extno = ino >> L2INOSPEREXT;
  	bitno = ino & (INOSPEREXT - 1);
  	mask = HIGHORDER >> bitno;
  
  	if (!(le32_to_cpu(iagp->wmap[extno]) & mask)) {
  		jfs_error(ip->i_sb,
  			  "diFree: wmap shows inode already free");
  	}
  
  	if (!addressPXD(&iagp->inoext[extno])) {
  		release_metapage(mp);
  		IREAD_UNLOCK(ipimap);
  		AG_UNLOCK(imap, agno);
  		jfs_error(ip->i_sb, "diFree: invalid inoext");
  		return -EIO;
  	}
  
  	/* compute the bitmap for the extent reflecting the freed inode.
  	 */
  	bitmap = le32_to_cpu(iagp->wmap[extno]) & ~mask;
  
  	if (imap->im_agctl[agno].numfree > imap->im_agctl[agno].numinos) {
  		release_metapage(mp);
  		IREAD_UNLOCK(ipimap);
  		AG_UNLOCK(imap, agno);
  		jfs_error(ip->i_sb, "diFree: numfree > numinos");
  		return -EIO;
  	}
  	/*
  	 *	inode extent still has some inodes or below low water mark:
  	 *	keep the inode extent;
  	 */
  	if (bitmap ||
  	    imap->im_agctl[agno].numfree < 96 ||
  	    (imap->im_agctl[agno].numfree < 288 &&
  	     (((imap->im_agctl[agno].numfree * 100) /
  	       imap->im_agctl[agno].numinos) <= 25))) {
  		/* if the iag currently has no free inodes (i.e.,
  		 * the inode being freed is the first free inode of iag),
  		 * insert the iag at head of the inode free list for the ag.
  		 */
  		if (iagp->nfreeinos == 0) {
  			/* check if there are any iags on the ag inode
  			 * free list.  if so, read the first one so that
  			 * we can link the current iag onto the list at
  			 * the head.
  			 */
  			if ((fwd = imap->im_agctl[agno].inofree) >= 0) {
  				/* read the iag that currently is the head
  				 * of the list.
  				 */
  				if ((rc = diIAGRead(imap, fwd, &amp))) {
  					IREAD_UNLOCK(ipimap);
  					AG_UNLOCK(imap, agno);
  					release_metapage(mp);
  					return (rc);
  				}
  				aiagp = (struct iag *) amp->data;
  
  				/* make current head point back to the iag.
  				 */
  				aiagp->inofreeback = cpu_to_le32(iagno);
  
  				write_metapage(amp);
  			}
  
  			/* iag points forward to current head and iag
  			 * becomes the new head of the list.
  			 */
  			iagp->inofreefwd =
  			    cpu_to_le32(imap->im_agctl[agno].inofree);
  			iagp->inofreeback = cpu_to_le32(-1);
  			imap->im_agctl[agno].inofree = iagno;
  		}
  		IREAD_UNLOCK(ipimap);
  
  		/* update the free inode summary map for the extent if
  		 * freeing the inode means the extent will now have free
  		 * inodes (i.e., the inode being freed is the first free
  		 * inode of extent),
  		 */
  		if (iagp->wmap[extno] == cpu_to_le32(ONES)) {
  			sword = extno >> L2EXTSPERSUM;
  			bitno = extno & (EXTSPERSUM - 1);
  			iagp->inosmap[sword] &=
  			    cpu_to_le32(~(HIGHORDER >> bitno));
  		}
  
  		/* update the bitmap.
  		 */
  		iagp->wmap[extno] = cpu_to_le32(bitmap);
  
  		/* update the free inode counts at the iag, ag and
  		 * map level.
  		 */
  		le32_add_cpu(&iagp->nfreeinos, 1);
  		imap->im_agctl[agno].numfree += 1;
  		atomic_inc(&imap->im_numfree);
  
  		/* release the AG inode map lock
  		 */
  		AG_UNLOCK(imap, agno);
  
  		/* write the iag */
  		write_metapage(mp);
  
  		return (0);
  	}
  
  
  	/*
  	 *	inode extent has become free and above low water mark:
  	 *	free the inode extent;
  	 */
  
  	/*
  	 *	prepare to update iag list(s) (careful update step 1)
  	 */
  	amp = bmp = cmp = dmp = NULL;
  	fwd = back = -1;
  
  	/* check if the iag currently has no free extents.  if so,
  	 * it will be placed on the head of the ag extent free list.
  	 */
  	if (iagp->nfreeexts == 0) {
  		/* check if the ag extent free list has any iags.
  		 * if so, read the iag at the head of the list now.
  		 * this (head) iag will be updated later to reflect
  		 * the addition of the current iag at the head of
  		 * the list.
  		 */
  		if ((fwd = imap->im_agctl[agno].extfree) >= 0) {
  			if ((rc = diIAGRead(imap, fwd, &amp)))
  				goto error_out;
  			aiagp = (struct iag *) amp->data;
  		}
  	} else {
  		/* iag has free extents. check if the addition of a free
  		 * extent will cause all extents to be free within this
  		 * iag.  if so, the iag will be removed from the ag extent
  		 * free list and placed on the inode map's free iag list.
  		 */
  		if (iagp->nfreeexts == cpu_to_le32(EXTSPERIAG - 1)) {
  			/* in preparation for removing the iag from the
  			 * ag extent free list, read the iags preceding
  			 * and following the iag on the ag extent free
  			 * list.
  			 */
  			if ((fwd = le32_to_cpu(iagp->extfreefwd)) >= 0) {
  				if ((rc = diIAGRead(imap, fwd, &amp)))
  					goto error_out;
  				aiagp = (struct iag *) amp->data;
  			}
  
  			if ((back = le32_to_cpu(iagp->extfreeback)) >= 0) {
  				if ((rc = diIAGRead(imap, back, &bmp)))
  					goto error_out;
  				biagp = (struct iag *) bmp->data;
  			}
  		}
  	}
  
  	/* remove the iag from the ag inode free list if freeing
  	 * this extent cause the iag to have no free inodes.
  	 */
  	if (iagp->nfreeinos == cpu_to_le32(INOSPEREXT - 1)) {
  		int inofreeback = le32_to_cpu(iagp->inofreeback);
  		int inofreefwd = le32_to_cpu(iagp->inofreefwd);
  
  		/* in preparation for removing the iag from the
  		 * ag inode free list, read the iags preceding
  		 * and following the iag on the ag inode free
  		 * list.  before reading these iags, we must make
  		 * sure that we already don't have them in hand
  		 * from up above, since re-reading an iag (buffer)
  		 * we are currently holding would cause a deadlock.
  		 */
  		if (inofreefwd >= 0) {
  
  			if (inofreefwd == fwd)
  				ciagp = (struct iag *) amp->data;
  			else if (inofreefwd == back)
  				ciagp = (struct iag *) bmp->data;
  			else {
  				if ((rc =
  				     diIAGRead(imap, inofreefwd, &cmp)))
  					goto error_out;
  				ciagp = (struct iag *) cmp->data;
  			}
  			assert(ciagp != NULL);
  		}
  
  		if (inofreeback >= 0) {
  			if (inofreeback == fwd)
  				diagp = (struct iag *) amp->data;
  			else if (inofreeback == back)
  				diagp = (struct iag *) bmp->data;
  			else {
  				if ((rc =
  				     diIAGRead(imap, inofreeback, &dmp)))
  					goto error_out;
  				diagp = (struct iag *) dmp->data;
  			}
  			assert(diagp != NULL);
  		}
  	}
  
  	IREAD_UNLOCK(ipimap);
  
  	/*
  	 * invalidate any page of the inode extent freed from buffer cache;
  	 */
  	freepxd = iagp->inoext[extno];
  	invalidate_pxd_metapages(ip, freepxd);
  
  	/*
  	 *	update iag list(s) (careful update step 2)
  	 */
  	/* add the iag to the ag extent free list if this is the
  	 * first free extent for the iag.
  	 */
  	if (iagp->nfreeexts == 0) {
  		if (fwd >= 0)
  			aiagp->extfreeback = cpu_to_le32(iagno);
  
  		iagp->extfreefwd =
  		    cpu_to_le32(imap->im_agctl[agno].extfree);
  		iagp->extfreeback = cpu_to_le32(-1);
  		imap->im_agctl[agno].extfree = iagno;
  	} else {
  		/* remove the iag from the ag extent list if all extents
  		 * are now free and place it on the inode map iag free list.
  		 */
  		if (iagp->nfreeexts == cpu_to_le32(EXTSPERIAG - 1)) {
  			if (fwd >= 0)
  				aiagp->extfreeback = iagp->extfreeback;
  
  			if (back >= 0)
  				biagp->extfreefwd = iagp->extfreefwd;
  			else
  				imap->im_agctl[agno].extfree =
  				    le32_to_cpu(iagp->extfreefwd);
  
  			iagp->extfreefwd = iagp->extfreeback = cpu_to_le32(-1);
  
  			IAGFREE_LOCK(imap);
  			iagp->iagfree = cpu_to_le32(imap->im_freeiag);
  			imap->im_freeiag = iagno;
  			IAGFREE_UNLOCK(imap);
  		}
  	}
  
  	/* remove the iag from the ag inode free list if freeing
  	 * this extent causes the iag to have no free inodes.
  	 */
  	if (iagp->nfreeinos == cpu_to_le32(INOSPEREXT - 1)) {
  		if ((int) le32_to_cpu(iagp->inofreefwd) >= 0)
  			ciagp->inofreeback = iagp->inofreeback;
  
  		if ((int) le32_to_cpu(iagp->inofreeback) >= 0)
  			diagp->inofreefwd = iagp->inofreefwd;
  		else
  			imap->im_agctl[agno].inofree =
  			    le32_to_cpu(iagp->inofreefwd);
  
  		iagp->inofreefwd = iagp->inofreeback = cpu_to_le32(-1);
  	}
  
  	/* update the inode extent address and working map
  	 * to reflect the free extent.
  	 * the permanent map should have been updated already
  	 * for the inode being freed.
  	 */
  	if (iagp->pmap[extno] != 0) {
  		jfs_error(ip->i_sb, "diFree: the pmap does not show inode free");
  	}
  	iagp->wmap[extno] = 0;
  	PXDlength(&iagp->inoext[extno], 0);
  	PXDaddress(&iagp->inoext[extno], 0);
  
  	/* update the free extent and free inode summary maps
  	 * to reflect the freed extent.
  	 * the inode summary map is marked to indicate no inodes
  	 * available for the freed extent.
  	 */
  	sword = extno >> L2EXTSPERSUM;
  	bitno = extno & (EXTSPERSUM - 1);
  	mask = HIGHORDER >> bitno;
  	iagp->inosmap[sword] |= cpu_to_le32(mask);
  	iagp->extsmap[sword] &= cpu_to_le32(~mask);
  
  	/* update the number of free inodes and number of free extents
  	 * for the iag.
  	 */
  	le32_add_cpu(&iagp->nfreeinos, -(INOSPEREXT - 1));
  	le32_add_cpu(&iagp->nfreeexts, 1);
  
  	/* update the number of free inodes and backed inodes
  	 * at the ag and inode map level.
  	 */
  	imap->im_agctl[agno].numfree -= (INOSPEREXT - 1);
  	imap->im_agctl[agno].numinos -= INOSPEREXT;
  	atomic_sub(INOSPEREXT - 1, &imap->im_numfree);
  	atomic_sub(INOSPEREXT, &imap->im_numinos);
  
  	if (amp)
  		write_metapage(amp);
  	if (bmp)
  		write_metapage(bmp);
  	if (cmp)
  		write_metapage(cmp);
  	if (dmp)
  		write_metapage(dmp);
  
  	/*
  	 * start transaction to update block allocation map
  	 * for the inode extent freed;
  	 *
  	 * N.B. AG_LOCK is released and iag will be released below, and
  	 * other thread may allocate inode from/reusing the ixad freed
  	 * BUT with new/different backing inode extent from the extent
  	 * to be freed by the transaction;
  	 */
  	tid = txBegin(ipimap->i_sb, COMMIT_FORCE);
  	mutex_lock(&JFS_IP(ipimap)->commit_mutex);
  
  	/* acquire tlock of the iag page of the freed ixad
  	 * to force the page NOHOMEOK (even though no data is
  	 * logged from the iag page) until NOREDOPAGE|FREEXTENT log
  	 * for the free of the extent is committed;
  	 * write FREEXTENT|NOREDOPAGE log record
  	 * N.B. linelock is overlaid as freed extent descriptor;
  	 */
  	tlck = txLock(tid, ipimap, mp, tlckINODE | tlckFREE);
  	pxdlock = (struct pxd_lock *) & tlck->lock;
  	pxdlock->flag = mlckFREEPXD;
  	pxdlock->pxd = freepxd;
  	pxdlock->index = 1;
  
  	write_metapage(mp);
  
  	iplist[0] = ipimap;
  
  	/*
  	 * logredo needs the IAG number and IAG extent index in order
  	 * to ensure that the IMap is consistent.  The least disruptive
  	 * way to pass these values through  to the transaction manager
  	 * is in the iplist array.
  	 *
  	 * It's not pretty, but it works.
  	 */
  	iplist[1] = (struct inode *) (size_t)iagno;
  	iplist[2] = (struct inode *) (size_t)extno;
  
  	rc = txCommit(tid, 1, &iplist[0], COMMIT_FORCE);
  
  	txEnd(tid);
  	mutex_unlock(&JFS_IP(ipimap)->commit_mutex);
  
  	/* unlock the AG inode map information */
  	AG_UNLOCK(imap, agno);
  
  	return (0);
  
        error_out:
  	IREAD_UNLOCK(ipimap);
  
  	if (amp)
  		release_metapage(amp);
  	if (bmp)
  		release_metapage(bmp);
  	if (cmp)
  		release_metapage(cmp);
  	if (dmp)
  		release_metapage(dmp);
  
  	AG_UNLOCK(imap, agno);
  
  	release_metapage(mp);
  
  	return (rc);
  }
  
  /*
   * There are several places in the diAlloc* routines where we initialize
   * the inode.
   */
  static inline void
  diInitInode(struct inode *ip, int iagno, int ino, int extno, struct iag * iagp)
  {
  	struct jfs_inode_info *jfs_ip = JFS_IP(ip);
  
  	ip->i_ino = (iagno << L2INOSPERIAG) + ino;
  	jfs_ip->ixpxd = iagp->inoext[extno];
  	jfs_ip->agstart = le64_to_cpu(iagp->agstart);
  	jfs_ip->active_ag = -1;
  }
  
  
  /*
   * NAME:	diAlloc(pip,dir,ip)
   *
   * FUNCTION:	allocate a disk inode from the inode working map
   *		for a fileset or aggregate.
   *
   * PARAMETERS:
   *	pip	- pointer to incore inode for the parent inode.
   *	dir	- 'true' if the new disk inode is for a directory.
   *	ip	- pointer to a new inode
   *
   * RETURN VALUES:
   *	0	- success.
   *	-ENOSPC	- insufficient disk resources.
   *	-EIO	- i/o error.
   */
  int diAlloc(struct inode *pip, bool dir, struct inode *ip)
  {
  	int rc, ino, iagno, addext, extno, bitno, sword;
  	int nwords, rem, i, agno;
  	u32 mask, inosmap, extsmap;
  	struct inode *ipimap;
  	struct metapage *mp;
  	ino_t inum;
  	struct iag *iagp;
  	struct inomap *imap;
  
  	/* get the pointers to the inode map inode and the
  	 * corresponding imap control structure.
  	 */
  	ipimap = JFS_SBI(pip->i_sb)->ipimap;
  	imap = JFS_IP(ipimap)->i_imap;
  	JFS_IP(ip)->ipimap = ipimap;
  	JFS_IP(ip)->fileset = FILESYSTEM_I;
  
  	/* for a directory, the allocation policy is to start
  	 * at the ag level using the preferred ag.
  	 */
  	if (dir) {
  		agno = dbNextAG(JFS_SBI(pip->i_sb)->ipbmap);
  		AG_LOCK(imap, agno);
  		goto tryag;
  	}
  
  	/* for files, the policy starts off by trying to allocate from
  	 * the same iag containing the parent disk inode:
  	 * try to allocate the new disk inode close to the parent disk
  	 * inode, using parent disk inode number + 1 as the allocation
  	 * hint.  (we use a left-to-right policy to attempt to avoid
  	 * moving backward on the disk.)  compute the hint within the
  	 * file system and the iag.
  	 */
  
  	/* get the ag number of this iag */
  	agno = BLKTOAG(JFS_IP(pip)->agstart, JFS_SBI(pip->i_sb));
  
  	if (atomic_read(&JFS_SBI(pip->i_sb)->bmap->db_active[agno])) {
  		/*
  		 * There is an open file actively growing.  We want to
  		 * allocate new inodes from a different ag to avoid
  		 * fragmentation problems.
  		 */
  		agno = dbNextAG(JFS_SBI(pip->i_sb)->ipbmap);
  		AG_LOCK(imap, agno);
  		goto tryag;
  	}
  
  	inum = pip->i_ino + 1;
  	ino = inum & (INOSPERIAG - 1);
  
  	/* back off the hint if it is outside of the iag */
  	if (ino == 0)
  		inum = pip->i_ino;
  
  	/* lock the AG inode map information */
  	AG_LOCK(imap, agno);
  
  	/* Get read lock on imap inode */
  	IREAD_LOCK(ipimap, RDWRLOCK_IMAP);
  
  	/* get the iag number and read the iag */
  	iagno = INOTOIAG(inum);
  	if ((rc = diIAGRead(imap, iagno, &mp))) {
  		IREAD_UNLOCK(ipimap);
  		AG_UNLOCK(imap, agno);
  		return (rc);
  	}
  	iagp = (struct iag *) mp->data;
  
  	/* determine if new inode extent is allowed to be added to the iag.
  	 * new inode extent can be added to the iag if the ag
  	 * has less than 32 free disk inodes and the iag has free extents.
  	 */
  	addext = (imap->im_agctl[agno].numfree < 32 && iagp->nfreeexts);
  
  	/*
  	 *	try to allocate from the IAG
  	 */
  	/* check if the inode may be allocated from the iag
  	 * (i.e. the inode has free inodes or new extent can be added).
  	 */
  	if (iagp->nfreeinos || addext) {
  		/* determine the extent number of the hint.
  		 */
  		extno = ino >> L2INOSPEREXT;
  
  		/* check if the extent containing the hint has backed
  		 * inodes.  if so, try to allocate within this extent.
  		 */
  		if (addressPXD(&iagp->inoext[extno])) {
  			bitno = ino & (INOSPEREXT - 1);
  			if ((bitno =
  			     diFindFree(le32_to_cpu(iagp->wmap[extno]),
  					bitno))
  			    < INOSPEREXT) {
  				ino = (extno << L2INOSPEREXT) + bitno;
  
  				/* a free inode (bit) was found within this
  				 * extent, so allocate it.
  				 */
  				rc = diAllocBit(imap, iagp, ino);
  				IREAD_UNLOCK(ipimap);
  				if (rc) {
  					assert(rc == -EIO);
  				} else {
  					/* set the results of the allocation
  					 * and write the iag.
  					 */
  					diInitInode(ip, iagno, ino, extno,
  						    iagp);
  					mark_metapage_dirty(mp);
  				}
  				release_metapage(mp);
  
  				/* free the AG lock and return.
  				 */
  				AG_UNLOCK(imap, agno);
  				return (rc);
  			}
  
  			if (!addext)
  				extno =
  				    (extno ==
  				     EXTSPERIAG - 1) ? 0 : extno + 1;
  		}
  
  		/*
  		 * no free inodes within the extent containing the hint.
  		 *
  		 * try to allocate from the backed extents following
  		 * hint or, if appropriate (i.e. addext is true), allocate
  		 * an extent of free inodes at or following the extent
  		 * containing the hint.
  		 *
  		 * the free inode and free extent summary maps are used
  		 * here, so determine the starting summary map position
  		 * and the number of words we'll have to examine.  again,
  		 * the approach is to allocate following the hint, so we
  		 * might have to initially ignore prior bits of the summary
  		 * map that represent extents prior to the extent containing
  		 * the hint and later revisit these bits.
  		 */
  		bitno = extno & (EXTSPERSUM - 1);
  		nwords = (bitno == 0) ? SMAPSZ : SMAPSZ + 1;
  		sword = extno >> L2EXTSPERSUM;
  
  		/* mask any prior bits for the starting words of the
  		 * summary map.
  		 */
  		mask = ONES << (EXTSPERSUM - bitno);
  		inosmap = le32_to_cpu(iagp->inosmap[sword]) | mask;
  		extsmap = le32_to_cpu(iagp->extsmap[sword]) | mask;
  
  		/* scan the free inode and free extent summary maps for
  		 * free resources.
  		 */
  		for (i = 0; i < nwords; i++) {
  			/* check if this word of the free inode summary
  			 * map describes an extent with free inodes.
  			 */
  			if (~inosmap) {
  				/* an extent with free inodes has been
  				 * found. determine the extent number
  				 * and the inode number within the extent.
  				 */
  				rem = diFindFree(inosmap, 0);
  				extno = (sword << L2EXTSPERSUM) + rem;
  				rem = diFindFree(le32_to_cpu(iagp->wmap[extno]),
  						 0);
  				if (rem >= INOSPEREXT) {
  					IREAD_UNLOCK(ipimap);
  					release_metapage(mp);
  					AG_UNLOCK(imap, agno);
  					jfs_error(ip->i_sb,
  						  "diAlloc: can't find free bit "
  						  "in wmap");
  					return -EIO;
  				}
  
  				/* determine the inode number within the
  				 * iag and allocate the inode from the
  				 * map.
  				 */
  				ino = (extno << L2INOSPEREXT) + rem;
  				rc = diAllocBit(imap, iagp, ino);
  				IREAD_UNLOCK(ipimap);
  				if (rc)
  					assert(rc == -EIO);
  				else {
  					/* set the results of the allocation
  					 * and write the iag.
  					 */
  					diInitInode(ip, iagno, ino, extno,
  						    iagp);
  					mark_metapage_dirty(mp);
  				}
  				release_metapage(mp);
  
  				/* free the AG lock and return.
  				 */
  				AG_UNLOCK(imap, agno);
  				return (rc);
  
  			}
  
  			/* check if we may allocate an extent of free
  			 * inodes and whether this word of the free
  			 * extents summary map describes a free extent.
  			 */
  			if (addext && ~extsmap) {
  				/* a free extent has been found.  determine
  				 * the extent number.
  				 */
  				rem = diFindFree(extsmap, 0);
  				extno = (sword << L2EXTSPERSUM) + rem;
  
  				/* allocate an extent of free inodes.
  				 */
  				if ((rc = diNewExt(imap, iagp, extno))) {
  					/* if there is no disk space for a
  					 * new extent, try to allocate the
  					 * disk inode from somewhere else.
  					 */
  					if (rc == -ENOSPC)
  						break;
  
  					assert(rc == -EIO);
  				} else {
  					/* set the results of the allocation
  					 * and write the iag.
  					 */
  					diInitInode(ip, iagno,
  						    extno << L2INOSPEREXT,
  						    extno, iagp);
  					mark_metapage_dirty(mp);
  				}
  				release_metapage(mp);
  				/* free the imap inode & the AG lock & return.
  				 */
  				IREAD_UNLOCK(ipimap);
  				AG_UNLOCK(imap, agno);
  				return (rc);
  			}
  
  			/* move on to the next set of summary map words.
  			 */
  			sword = (sword == SMAPSZ - 1) ? 0 : sword + 1;
  			inosmap = le32_to_cpu(iagp->inosmap[sword]);
  			extsmap = le32_to_cpu(iagp->extsmap[sword]);
  		}
  	}
  	/* unlock imap inode */
  	IREAD_UNLOCK(ipimap);
  
  	/* nothing doing in this iag, so release it. */
  	release_metapage(mp);
  
        tryag:
  	/*
  	 * try to allocate anywhere within the same AG as the parent inode.
  	 */
  	rc = diAllocAG(imap, agno, dir, ip);
  
  	AG_UNLOCK(imap, agno);
  
  	if (rc != -ENOSPC)
  		return (rc);
  
  	/*
  	 * try to allocate in any AG.
  	 */
  	return (diAllocAny(imap, agno, dir, ip));
  }
  
  
  /*
   * NAME:	diAllocAG(imap,agno,dir,ip)
   *
   * FUNCTION:	allocate a disk inode from the allocation group.
   *
   *		this routine first determines if a new extent of free
   *		inodes should be added for the allocation group, with
   *		the current request satisfied from this extent. if this
   *		is the case, an attempt will be made to do just that.  if
   *		this attempt fails or it has been determined that a new
   *		extent should not be added, an attempt is made to satisfy
   *		the request by allocating an existing (backed) free inode
   *		from the allocation group.
   *
   * PRE CONDITION: Already have the AG lock for this AG.
   *
   * PARAMETERS:
   *	imap	- pointer to inode map control structure.
   *	agno	- allocation group to allocate from.
   *	dir	- 'true' if the new disk inode is for a directory.
   *	ip	- pointer to the new inode to be filled in on successful return
   *		  with the disk inode number allocated, its extent address
   *		  and the start of the ag.
   *
   * RETURN VALUES:
   *	0	- success.
   *	-ENOSPC	- insufficient disk resources.
   *	-EIO	- i/o error.
   */
  static int
  diAllocAG(struct inomap * imap, int agno, bool dir, struct inode *ip)
  {
  	int rc, addext, numfree, numinos;
  
  	/* get the number of free and the number of backed disk
  	 * inodes currently within the ag.
  	 */
  	numfree = imap->im_agctl[agno].numfree;
  	numinos = imap->im_agctl[agno].numinos;
  
  	if (numfree > numinos) {
  		jfs_error(ip->i_sb, "diAllocAG: numfree > numinos");
  		return -EIO;
  	}
  
  	/* determine if we should allocate a new extent of free inodes
  	 * within the ag: for directory inodes, add a new extent
  	 * if there are a small number of free inodes or number of free
  	 * inodes is a small percentage of the number of backed inodes.
  	 */
  	if (dir)
  		addext = (numfree < 64 ||
  			  (numfree < 256
  			   && ((numfree * 100) / numinos) <= 20));
  	else
  		addext = (numfree == 0);
  
  	/*
  	 * try to allocate a new extent of free inodes.
  	 */
  	if (addext) {
  		/* if free space is not available for this new extent, try
  		 * below to allocate a free and existing (already backed)
  		 * inode from the ag.
  		 */
  		if ((rc = diAllocExt(imap, agno, ip)) != -ENOSPC)
  			return (rc);
  	}
  
  	/*
  	 * try to allocate an existing free inode from the ag.
  	 */
  	return (diAllocIno(imap, agno, ip));
  }
  
  
  /*
   * NAME:	diAllocAny(imap,agno,dir,iap)
   *
   * FUNCTION:	allocate a disk inode from any other allocation group.
   *
   *		this routine is called when an allocation attempt within
   *		the primary allocation group has failed. if attempts to
   *		allocate an inode from any allocation group other than the
   *		specified primary group.
   *
   * PARAMETERS:
   *	imap	- pointer to inode map control structure.
   *	agno	- primary allocation group (to avoid).
   *	dir	- 'true' if the new disk inode is for a directory.
   *	ip	- pointer to a new inode to be filled in on successful return
   *		  with the disk inode number allocated, its extent address
   *		  and the start of the ag.
   *
   * RETURN VALUES:
   *	0	- success.
   *	-ENOSPC	- insufficient disk resources.
   *	-EIO	- i/o error.
   */
  static int
  diAllocAny(struct inomap * imap, int agno, bool dir, struct inode *ip)
  {
  	int ag, rc;
  	int maxag = JFS_SBI(imap->im_ipimap->i_sb)->bmap->db_maxag;
  
  
  	/* try to allocate from the ags following agno up to
  	 * the maximum ag number.
  	 */
  	for (ag = agno + 1; ag <= maxag; ag++) {
  		AG_LOCK(imap, ag);
  
  		rc = diAllocAG(imap, ag, dir, ip);
  
  		AG_UNLOCK(imap, ag);
  
  		if (rc != -ENOSPC)
  			return (rc);
  	}
  
  	/* try to allocate from the ags in front of agno.
  	 */
  	for (ag = 0; ag < agno; ag++) {
  		AG_LOCK(imap, ag);
  
  		rc = diAllocAG(imap, ag, dir, ip);
  
  		AG_UNLOCK(imap, ag);
  
  		if (rc != -ENOSPC)
  			return (rc);
  	}
  
  	/* no free disk inodes.
  	 */
  	return -ENOSPC;
  }
  
  
  /*
   * NAME:	diAllocIno(imap,agno,ip)
   *
   * FUNCTION:	allocate a disk inode from the allocation group's free
   *		inode list, returning an error if this free list is
   *		empty (i.e. no iags on the list).
   *
   *		allocation occurs from the first iag on the list using
   *		the iag's free inode summary map to find the leftmost
   *		free inode in the iag.
   *
   * PRE CONDITION: Already have AG lock for this AG.
   *
   * PARAMETERS:
   *	imap	- pointer to inode map control structure.
   *	agno	- allocation group.
   *	ip	- pointer to new inode to be filled in on successful return
   *		  with the disk inode number allocated, its extent address
   *		  and the start of the ag.
   *
   * RETURN VALUES:
   *	0	- success.
   *	-ENOSPC	- insufficient disk resources.
   *	-EIO	- i/o error.
   */
  static int diAllocIno(struct inomap * imap, int agno, struct inode *ip)
  {
  	int iagno, ino, rc, rem, extno, sword;
  	struct metapage *mp;
  	struct iag *iagp;
  
  	/* check if there are iags on the ag's free inode list.
  	 */
  	if ((iagno = imap->im_agctl[agno].inofree) < 0)
  		return -ENOSPC;
  
  	/* obtain read lock on imap inode */
  	IREAD_LOCK(imap->im_ipimap, RDWRLOCK_IMAP);
  
  	/* read the iag at the head of the list.
  	 */
  	if ((rc = diIAGRead(imap, iagno, &mp))) {
  		IREAD_UNLOCK(imap->im_ipimap);
  		return (rc);
  	}
  	iagp = (struct iag *) mp->data;
  
  	/* better be free inodes in this iag if it is on the
  	 * list.
  	 */
  	if (!iagp->nfreeinos) {
  		IREAD_UNLOCK(imap->im_ipimap);
  		release_metapage(mp);
  		jfs_error(ip->i_sb,
  			  "diAllocIno: nfreeinos = 0, but iag on freelist");
  		return -EIO;
  	}
  
  	/* scan the free inode summary map to find an extent
  	 * with free inodes.
  	 */
  	for (sword = 0;; sword++) {
  		if (sword >= SMAPSZ) {
  			IREAD_UNLOCK(imap->im_ipimap);
  			release_metapage(mp);
  			jfs_error(ip->i_sb,
  				  "diAllocIno: free inode not found in summary map");
  			return -EIO;
  		}
  
  		if (~iagp->inosmap[sword])
  			break;
  	}
  
  	/* found a extent with free inodes. determine
  	 * the extent number.
  	 */
  	rem = diFindFree(le32_to_cpu(iagp->inosmap[sword]), 0);
  	if (rem >= EXTSPERSUM) {
  		IREAD_UNLOCK(imap->im_ipimap);
  		release_metapage(mp);
  		jfs_error(ip->i_sb, "diAllocIno: no free extent found");
  		return -EIO;
  	}
  	extno = (sword << L2EXTSPERSUM) + rem;
  
  	/* find the first free inode in the extent.
  	 */
  	rem = diFindFree(le32_to_cpu(iagp->wmap[extno]), 0);
  	if (rem >= INOSPEREXT) {
  		IREAD_UNLOCK(imap->im_ipimap);
  		release_metapage(mp);
  		jfs_error(ip->i_sb, "diAllocIno: free inode not found");
  		return -EIO;
  	}
  
  	/* compute the inode number within the iag.
  	 */
  	ino = (extno << L2INOSPEREXT) + rem;
  
  	/* allocate the inode.
  	 */
  	rc = diAllocBit(imap, iagp, ino);
  	IREAD_UNLOCK(imap->im_ipimap);
  	if (rc) {
  		release_metapage(mp);
  		return (rc);
  	}
  
  	/* set the results of the allocation and write the iag.
  	 */
  	diInitInode(ip, iagno, ino, extno, iagp);
  	write_metapage(mp);
  
  	return (0);
  }
  
  
  /*
   * NAME:	diAllocExt(imap,agno,ip)
   *
   * FUNCTION:	add a new extent of free inodes to an iag, allocating
   *		an inode from this extent to satisfy the current allocation
   *		request.
   *
   *		this routine first tries to find an existing iag with free
   *		extents through the ag free extent list.  if list is not
   *		empty, the head of the list will be selected as the home
   *		of the new extent of free inodes.  otherwise (the list is
   *		empty), a new iag will be allocated for the ag to contain
   *		the extent.
   *
   *		once an iag has been selected, the free extent summary map
   *		is used to locate a free extent within the iag and diNewExt()
   *		is called to initialize the extent, with initialization
   *		including the allocation of the first inode of the extent
   *		for the purpose of satisfying this request.
   *
   * PARAMETERS:
   *	imap	- pointer to inode map control structure.
   *	agno	- allocation group number.
   *	ip	- pointer to new inode to be filled in on successful return
   *		  with the disk inode number allocated, its extent address
   *		  and the start of the ag.
   *
   * RETURN VALUES:
   *	0	- success.
   *	-ENOSPC	- insufficient disk resources.
   *	-EIO	- i/o error.
   */
  static int diAllocExt(struct inomap * imap, int agno, struct inode *ip)
  {
  	int rem, iagno, sword, extno, rc;
  	struct metapage *mp;
  	struct iag *iagp;
  
  	/* check if the ag has any iags with free extents.  if not,
  	 * allocate a new iag for the ag.
  	 */
  	if ((iagno = imap->im_agctl[agno].extfree) < 0) {
  		/* If successful, diNewIAG will obtain the read lock on the
  		 * imap inode.
  		 */
  		if ((rc = diNewIAG(imap, &iagno, agno, &mp))) {
  			return (rc);
  		}
  		iagp = (struct iag *) mp->data;
  
  		/* set the ag number if this a brand new iag
  		 */
  		iagp->agstart =
  		    cpu_to_le64(AGTOBLK(agno, imap->im_ipimap));
  	} else {
  		/* read the iag.
  		 */
  		IREAD_LOCK(imap->im_ipimap, RDWRLOCK_IMAP);
  		if ((rc = diIAGRead(imap, iagno, &mp))) {
  			IREAD_UNLOCK(imap->im_ipimap);
  			jfs_error(ip->i_sb, "diAllocExt: error reading iag");
  			return rc;
  		}
  		iagp = (struct iag *) mp->data;
  	}
  
  	/* using the free extent summary map, find a free extent.
  	 */
  	for (sword = 0;; sword++) {
  		if (sword >= SMAPSZ) {
  			release_metapage(mp);
  			IREAD_UNLOCK(imap->im_ipimap);
  			jfs_error(ip->i_sb,
  				  "diAllocExt: free ext summary map not found");
  			return -EIO;
  		}
  		if (~iagp->extsmap[sword])
  			break;
  	}
  
  	/* determine the extent number of the free extent.
  	 */
  	rem = diFindFree(le32_to_cpu(iagp->extsmap[sword]), 0);
  	if (rem >= EXTSPERSUM) {
  		release_metapage(mp);
  		IREAD_UNLOCK(imap->im_ipimap);
  		jfs_error(ip->i_sb, "diAllocExt: free extent not found");
  		return -EIO;
  	}
  	extno = (sword << L2EXTSPERSUM) + rem;
  
  	/* initialize the new extent.
  	 */
  	rc = diNewExt(imap, iagp, extno);
  	IREAD_UNLOCK(imap->im_ipimap);
  	if (rc) {
  		/* something bad happened.  if a new iag was allocated,
  		 * place it back on the inode map's iag free list, and
  		 * clear the ag number information.
  		 */
  		if (iagp->nfreeexts == cpu_to_le32(EXTSPERIAG)) {
  			IAGFREE_LOCK(imap);
  			iagp->iagfree = cpu_to_le32(imap->im_freeiag);
  			imap->im_freeiag = iagno;
  			IAGFREE_UNLOCK(imap);
  		}
  		write_metapage(mp);
  		return (rc);
  	}
  
  	/* set the results of the allocation and write the iag.
  	 */
  	diInitInode(ip, iagno, extno << L2INOSPEREXT, extno, iagp);
  
  	write_metapage(mp);
  
  	return (0);
  }
  
  
  /*
   * NAME:	diAllocBit(imap,iagp,ino)
   *
   * FUNCTION:	allocate a backed inode from an iag.
   *
   *		this routine performs the mechanics of allocating a
   *		specified inode from a backed extent.
   *
   *		if the inode to be allocated represents the last free
   *		inode within the iag, the iag will be removed from the
   *		ag free inode list.
   *
   *		a careful update approach is used to provide consistency
   *		in the face of updates to multiple buffers.  under this
   *		approach, all required buffers are obtained before making
   *		any updates and are held all are updates are complete.
   *
   * PRE CONDITION: Already have buffer lock on iagp.  Already have AG lock on
   *	this AG.  Must have read lock on imap inode.
   *
   * PARAMETERS:
   *	imap	- pointer to inode map control structure.
   *	iagp	- pointer to iag.
   *	ino	- inode number to be allocated within the iag.
   *
   * RETURN VALUES:
   *	0	- success.
   *	-ENOSPC	- insufficient disk resources.
   *	-EIO	- i/o error.
   */
  static int diAllocBit(struct inomap * imap, struct iag * iagp, int ino)
  {
  	int extno, bitno, agno, sword, rc;
  	struct metapage *amp = NULL, *bmp = NULL;
  	struct iag *aiagp = NULL, *biagp = NULL;
  	u32 mask;
  
  	/* check if this is the last free inode within the iag.
  	 * if so, it will have to be removed from the ag free
  	 * inode list, so get the iags preceding and following
  	 * it on the list.
  	 */
  	if (iagp->nfreeinos == cpu_to_le32(1)) {
  		if ((int) le32_to_cpu(iagp->inofreefwd) >= 0) {
  			if ((rc =
  			     diIAGRead(imap, le32_to_cpu(iagp->inofreefwd),
  				       &amp)))
  				return (rc);
  			aiagp = (struct iag *) amp->data;
  		}
  
  		if ((int) le32_to_cpu(iagp->inofreeback) >= 0) {
  			if ((rc =
  			     diIAGRead(imap,
  				       le32_to_cpu(iagp->inofreeback),
  				       &bmp))) {
  				if (amp)
  					release_metapage(amp);
  				return (rc);
  			}
  			biagp = (struct iag *) bmp->data;
  		}
  	}
  
  	/* get the ag number, extent number, inode number within
  	 * the extent.
  	 */
  	agno = BLKTOAG(le64_to_cpu(iagp->agstart), JFS_SBI(imap->im_ipimap->i_sb));
  	extno = ino >> L2INOSPEREXT;
  	bitno = ino & (INOSPEREXT - 1);
  
  	/* compute the mask for setting the map.
  	 */
  	mask = HIGHORDER >> bitno;
  
  	/* the inode should be free and backed.
  	 */
  	if (((le32_to_cpu(iagp->pmap[extno]) & mask) != 0) ||
  	    ((le32_to_cpu(iagp->wmap[extno]) & mask) != 0) ||
  	    (addressPXD(&iagp->inoext[extno]) == 0)) {
  		if (amp)
  			release_metapage(amp);
  		if (bmp)
  			release_metapage(bmp);
  
  		jfs_error(imap->im_ipimap->i_sb,
  			  "diAllocBit: iag inconsistent");
  		return -EIO;
  	}
  
  	/* mark the inode as allocated in the working map.
  	 */
  	iagp->wmap[extno] |= cpu_to_le32(mask);
  
  	/* check if all inodes within the extent are now
  	 * allocated.  if so, update the free inode summary
  	 * map to reflect this.
  	 */
  	if (iagp->wmap[extno] == cpu_to_le32(ONES)) {
  		sword = extno >> L2EXTSPERSUM;
  		bitno = extno & (EXTSPERSUM - 1);
  		iagp->inosmap[sword] |= cpu_to_le32(HIGHORDER >> bitno);
  	}
  
  	/* if this was the last free inode in the iag, remove the
  	 * iag from the ag free inode list.
  	 */
  	if (iagp->nfreeinos == cpu_to_le32(1)) {
  		if (amp) {
  			aiagp->inofreeback = iagp->inofreeback;
  			write_metapage(amp);
  		}
  
  		if (bmp) {
  			biagp->inofreefwd = iagp->inofreefwd;
  			write_metapage(bmp);
  		} else {
  			imap->im_agctl[agno].inofree =
  			    le32_to_cpu(iagp->inofreefwd);
  		}
  		iagp->inofreefwd = iagp->inofreeback = cpu_to_le32(-1);
  	}
  
  	/* update the free inode count at the iag, ag, inode
  	 * map levels.
  	 */
  	le32_add_cpu(&iagp->nfreeinos, -1);
  	imap->im_agctl[agno].numfree -= 1;
  	atomic_dec(&imap->im_numfree);
  
  	return (0);
  }
  
  
  /*
   * NAME:	diNewExt(imap,iagp,extno)
   *
   * FUNCTION:	initialize a new extent of inodes for an iag, allocating
   *		the first inode of the extent for use for the current
   *		allocation request.
   *
   *		disk resources are allocated for the new extent of inodes
   *		and the inodes themselves are initialized to reflect their
   *		existence within the extent (i.e. their inode numbers and
   *		inode extent addresses are set) and their initial state
   *		(mode and link count are set to zero).
   *
   *		if the iag is new, it is not yet on an ag extent free list
   *		but will now be placed on this list.
   *
   *		if the allocation of the new extent causes the iag to
   *		have no free extent, the iag will be removed from the
   *		ag extent free list.
   *
   *		if the iag has no free backed inodes, it will be placed
   *		on the ag free inode list, since the addition of the new
   *		extent will now cause it to have free inodes.
   *
   *		a careful update approach is used to provide consistency
   *		(i.e. list consistency) in the face of updates to multiple
   *		buffers.  under this approach, all required buffers are
   *		obtained before making any updates and are held until all
   *		updates are complete.
   *
   * PRE CONDITION: Already have buffer lock on iagp.  Already have AG lock on
   *	this AG.  Must have read lock on imap inode.
   *
   * PARAMETERS:
   *	imap	- pointer to inode map control structure.
   *	iagp	- pointer to iag.
   *	extno	- extent number.
   *
   * RETURN VALUES:
   *	0	- success.
   *	-ENOSPC	- insufficient disk resources.
   *	-EIO	- i/o error.
   */
  static int diNewExt(struct inomap * imap, struct iag * iagp, int extno)
  {
  	int agno, iagno, fwd, back, freei = 0, sword, rc;
  	struct iag *aiagp = NULL, *biagp = NULL, *ciagp = NULL;
  	struct metapage *amp, *bmp, *cmp, *dmp;
  	struct inode *ipimap;
  	s64 blkno, hint;
  	int i, j;
  	u32 mask;
  	ino_t ino;
  	struct dinode *dp;
  	struct jfs_sb_info *sbi;
  
  	/* better have free extents.
  	 */
  	if (!iagp->nfreeexts) {
  		jfs_error(imap->im_ipimap->i_sb, "diNewExt: no free extents");
  		return -EIO;
  	}
  
  	/* get the inode map inode.
  	 */
  	ipimap = imap->im_ipimap;
  	sbi = JFS_SBI(ipimap->i_sb);
  
  	amp = bmp = cmp = NULL;
  
  	/* get the ag and iag numbers for this iag.
  	 */
  	agno = BLKTOAG(le64_to_cpu(iagp->agstart), sbi);
  	iagno = le32_to_cpu(iagp->iagnum);
  
  	/* check if this is the last free extent within the
  	 * iag.  if so, the iag must be removed from the ag
  	 * free extent list, so get the iags preceding and
  	 * following the iag on this list.
  	 */
  	if (iagp->nfreeexts == cpu_to_le32(1)) {
  		if ((fwd = le32_to_cpu(iagp->extfreefwd)) >= 0) {
  			if ((rc = diIAGRead(imap, fwd, &amp)))
  				return (rc);
  			aiagp = (struct iag *) amp->data;
  		}
  
  		if ((back = le32_to_cpu(iagp->extfreeback)) >= 0) {
  			if ((rc = diIAGRead(imap, back, &bmp)))
  				goto error_out;
  			biagp = (struct iag *) bmp->data;
  		}
  	} else {
  		/* the iag has free extents.  if all extents are free
  		 * (as is the case for a newly allocated iag), the iag
  		 * must be added to the ag free extent list, so get
  		 * the iag at the head of the list in preparation for
  		 * adding this iag to this list.
  		 */
  		fwd = back = -1;
  		if (iagp->nfreeexts == cpu_to_le32(EXTSPERIAG)) {
  			if ((fwd = imap->im_agctl[agno].extfree) >= 0) {
  				if ((rc = diIAGRead(imap, fwd, &amp)))
  					goto error_out;
  				aiagp = (struct iag *) amp->data;
  			}
  		}
  	}
  
  	/* check if the iag has no free inodes.  if so, the iag
  	 * will have to be added to the ag free inode list, so get
  	 * the iag at the head of the list in preparation for
  	 * adding this iag to this list.  in doing this, we must
  	 * check if we already have the iag at the head of
  	 * the list in hand.
  	 */
  	if (iagp->nfreeinos == 0) {
  		freei = imap->im_agctl[agno].inofree;
  
  		if (freei >= 0) {
  			if (freei == fwd) {
  				ciagp = aiagp;
  			} else if (freei == back) {
  				ciagp = biagp;
  			} else {
  				if ((rc = diIAGRead(imap, freei, &cmp)))
  					goto error_out;
  				ciagp = (struct iag *) cmp->data;
  			}
  			if (ciagp == NULL) {
  				jfs_error(imap->im_ipimap->i_sb,
  					  "diNewExt: ciagp == NULL");
  				rc = -EIO;
  				goto error_out;
  			}
  		}
  	}
  
  	/* allocate disk space for the inode extent.
  	 */
  	if ((extno == 0) || (addressPXD(&iagp->inoext[extno - 1]) == 0))
  		hint = ((s64) agno << sbi->bmap->db_agl2size) - 1;
  	else
  		hint = addressPXD(&iagp->inoext[extno - 1]) +
  		    lengthPXD(&iagp->inoext[extno - 1]) - 1;
  
  	if ((rc = dbAlloc(ipimap, hint, (s64) imap->im_nbperiext, &blkno)))
  		goto error_out;
  
  	/* compute the inode number of the first inode within the
  	 * extent.
  	 */
  	ino = (iagno << L2INOSPERIAG) + (extno << L2INOSPEREXT);
  
  	/* initialize the inodes within the newly allocated extent a
  	 * page at a time.
  	 */
  	for (i = 0; i < imap->im_nbperiext; i += sbi->nbperpage) {
  		/* get a buffer for this page of disk inodes.
  		 */
  		dmp = get_metapage(ipimap, blkno + i, PSIZE, 1);
  		if (dmp == NULL) {
  			rc = -EIO;
  			goto error_out;
  		}
  		dp = (struct dinode *) dmp->data;
  
  		/* initialize the inode number, mode, link count and
  		 * inode extent address.
  		 */
  		for (j = 0; j < INOSPERPAGE; j++, dp++, ino++) {
  			dp->di_inostamp = cpu_to_le32(sbi->inostamp);
  			dp->di_number = cpu_to_le32(ino);
  			dp->di_fileset = cpu_to_le32(FILESYSTEM_I);
  			dp->di_mode = 0;
  			dp->di_nlink = 0;
  			PXDaddress(&(dp->di_ixpxd), blkno);
  			PXDlength(&(dp->di_ixpxd), imap->im_nbperiext);
  		}
  		write_metapage(dmp);
  	}
  
  	/* if this is the last free extent within the iag, remove the
  	 * iag from the ag free extent list.
  	 */
  	if (iagp->nfreeexts == cpu_to_le32(1)) {
  		if (fwd >= 0)
  			aiagp->extfreeback = iagp->extfreeback;
  
  		if (back >= 0)
  			biagp->extfreefwd = iagp->extfreefwd;
  		else
  			imap->im_agctl[agno].extfree =
  			    le32_to_cpu(iagp->extfreefwd);
  
  		iagp->extfreefwd = iagp->extfreeback = cpu_to_le32(-1);
  	} else {
  		/* if the iag has all free extents (newly allocated iag),
  		 * add the iag to the ag free extent list.
  		 */
  		if (iagp->nfreeexts == cpu_to_le32(EXTSPERIAG)) {
  			if (fwd >= 0)
  				aiagp->extfreeback = cpu_to_le32(iagno);
  
  			iagp->extfreefwd = cpu_to_le32(fwd);
  			iagp->extfreeback = cpu_to_le32(-1);
  			imap->im_agctl[agno].extfree = iagno;
  		}
  	}
  
  	/* if the iag has no free inodes, add the iag to the
  	 * ag free inode list.
  	 */
  	if (iagp->nfreeinos == 0) {
  		if (freei >= 0)
  			ciagp->inofreeback = cpu_to_le32(iagno);
  
  		iagp->inofreefwd =
  		    cpu_to_le32(imap->im_agctl[agno].inofree);
  		iagp->inofreeback = cpu_to_le32(-1);
  		imap->im_agctl[agno].inofree = iagno;
  	}
  
  	/* initialize the extent descriptor of the extent. */
  	PXDlength(&iagp->inoext[extno], imap->im_nbperiext);
  	PXDaddress(&iagp->inoext[extno], blkno);
  
  	/* initialize the working and persistent map of the extent.
  	 * the working map will be initialized such that
  	 * it indicates the first inode of the extent is allocated.
  	 */
  	iagp->wmap[extno] = cpu_to_le32(HIGHORDER);
  	iagp->pmap[extno] = 0;
  
  	/* update the free inode and free extent summary maps
  	 * for the extent to indicate the extent has free inodes
  	 * and no longer represents a free extent.
  	 */
  	sword = extno >> L2EXTSPERSUM;
  	mask = HIGHORDER >> (extno & (EXTSPERSUM - 1));
  	iagp->extsmap[sword] |= cpu_to_le32(mask);
  	iagp->inosmap[sword] &= cpu_to_le32(~mask);
  
  	/* update the free inode and free extent counts for the
  	 * iag.
  	 */
  	le32_add_cpu(&iagp->nfreeinos, (INOSPEREXT - 1));
  	le32_add_cpu(&iagp->nfreeexts, -1);
  
  	/* update the free and backed inode counts for the ag.
  	 */
  	imap->im_agctl[agno].numfree += (INOSPEREXT - 1);
  	imap->im_agctl[agno].numinos += INOSPEREXT;
  
  	/* update the free and backed inode counts for the inode map.
  	 */
  	atomic_add(INOSPEREXT - 1, &imap->im_numfree);
  	atomic_add(INOSPEREXT, &imap->im_numinos);
  
  	/* write the iags.
  	 */
  	if (amp)
  		write_metapage(amp);
  	if (bmp)
  		write_metapage(bmp);
  	if (cmp)
  		write_metapage(cmp);
  
  	return (0);
  
        error_out:
  
  	/* release the iags.
  	 */
  	if (amp)
  		release_metapage(amp);
  	if (bmp)
  		release_metapage(bmp);
  	if (cmp)
  		release_metapage(cmp);
  
  	return (rc);
  }
  
  
  /*
   * NAME:	diNewIAG(imap,iagnop,agno)
   *
   * FUNCTION:	allocate a new iag for an allocation group.
   *
   *		first tries to allocate the iag from the inode map
   *		iagfree list:
   *		if the list has free iags, the head of the list is removed
   *		and returned to satisfy the request.
   *		if the inode map's iag free list is empty, the inode map
   *		is extended to hold a new iag. this new iag is initialized
   *		and returned to satisfy the request.
   *
   * PARAMETERS:
   *	imap	- pointer to inode map control structure.
   *	iagnop	- pointer to an iag number set with the number of the
   *		  newly allocated iag upon successful return.
   *	agno	- allocation group number.
   *	bpp	- Buffer pointer to be filled in with new IAG's buffer
   *
   * RETURN VALUES:
   *	0	- success.
   *	-ENOSPC	- insufficient disk resources.
   *	-EIO	- i/o error.
   *
   * serialization:
   *	AG lock held on entry/exit;
   *	write lock on the map is held inside;
   *	read lock on the map is held on successful completion;
   *
   * note: new iag transaction:
   * . synchronously write iag;
   * . write log of xtree and inode of imap;
   * . commit;
   * . synchronous write of xtree (right to left, bottom to top);
   * . at start of logredo(): init in-memory imap with one additional iag page;
   * . at end of logredo(): re-read imap inode to determine
   *   new imap size;
   */
  static int
  diNewIAG(struct inomap * imap, int *iagnop, int agno, struct metapage ** mpp)
  {
  	int rc;
  	int iagno, i, xlen;
  	struct inode *ipimap;
  	struct super_block *sb;
  	struct jfs_sb_info *sbi;
  	struct metapage *mp;
  	struct iag *iagp;
  	s64 xaddr = 0;
  	s64 blkno;
  	tid_t tid;
  	struct inode *iplist[1];
  
  	/* pick up pointers to the inode map and mount inodes */
  	ipimap = imap->im_ipimap;
  	sb = ipimap->i_sb;
  	sbi = JFS_SBI(sb);
  
  	/* acquire the free iag lock */
  	IAGFREE_LOCK(imap);
  
  	/* if there are any iags on the inode map free iag list,
  	 * allocate the iag from the head of the list.
  	 */
  	if (imap->im_freeiag >= 0) {
  		/* pick up the iag number at the head of the list */
  		iagno = imap->im_freeiag;
  
  		/* determine the logical block number of the iag */
  		blkno = IAGTOLBLK(iagno, sbi->l2nbperpage);
  	} else {
  		/* no free iags. the inode map will have to be extented
  		 * to include a new iag.
  		 */
  
  		/* acquire inode map lock */
  		IWRITE_LOCK(ipimap, RDWRLOCK_IMAP);
  
  		if (ipimap->i_size >> L2PSIZE != imap->im_nextiag + 1) {
  			IWRITE_UNLOCK(ipimap);
  			IAGFREE_UNLOCK(imap);
  			jfs_error(imap->im_ipimap->i_sb,
  				  "diNewIAG: ipimap->i_size is wrong");
  			return -EIO;
  		}
  
  
  		/* get the next available iag number */
  		iagno = imap->im_nextiag;
  
  		/* make sure that we have not exceeded the maximum inode
  		 * number limit.
  		 */
  		if (iagno > (MAXIAGS - 1)) {
  			/* release the inode map lock */
  			IWRITE_UNLOCK(ipimap);
  
  			rc = -ENOSPC;
  			goto out;
  		}
  
  		/*
  		 * synchronously append new iag page.
  		 */
  		/* determine the logical address of iag page to append */
  		blkno = IAGTOLBLK(iagno, sbi->l2nbperpage);
  
  		/* Allocate extent for new iag page */
  		xlen = sbi->nbperpage;
  		if ((rc = dbAlloc(ipimap, 0, (s64) xlen, &xaddr))) {
  			/* release the inode map lock */
  			IWRITE_UNLOCK(ipimap);
  
  			goto out;
  		}
  
  		/*
  		 * start transaction of update of the inode map
  		 * addressing structure pointing to the new iag page;
  		 */
  		tid = txBegin(sb, COMMIT_FORCE);
  		mutex_lock(&JFS_IP(ipimap)->commit_mutex);
  
  		/* update the inode map addressing structure to point to it */
  		if ((rc =
  		     xtInsert(tid, ipimap, 0, blkno, xlen, &xaddr, 0))) {
  			txEnd(tid);
  			mutex_unlock(&JFS_IP(ipimap)->commit_mutex);
  			/* Free the blocks allocated for the iag since it was
  			 * not successfully added to the inode map
  			 */
  			dbFree(ipimap, xaddr, (s64) xlen);
  
  			/* release the inode map lock */
  			IWRITE_UNLOCK(ipimap);
  
  			goto out;
  		}
  
  		/* update the inode map's inode to reflect the extension */
  		ipimap->i_size += PSIZE;
  		inode_add_bytes(ipimap, PSIZE);
  
  		/* assign a buffer for the page */
  		mp = get_metapage(ipimap, blkno, PSIZE, 0);
  		if (!mp) {
  			/*
  			 * This is very unlikely since we just created the
  			 * extent, but let's try to handle it correctly
  			 */
  			xtTruncate(tid, ipimap, ipimap->i_size - PSIZE,
  				   COMMIT_PWMAP);
  
  			txAbort(tid, 0);
  			txEnd(tid);
  			mutex_unlock(&JFS_IP(ipimap)->commit_mutex);
  
  			/* release the inode map lock */
  			IWRITE_UNLOCK(ipimap);
  
  			rc = -EIO;
  			goto out;
  		}
  		iagp = (struct iag *) mp->data;
  
  		/* init the iag */
  		memset(iagp, 0, sizeof(struct iag));
  		iagp->iagnum = cpu_to_le32(iagno);
  		iagp->inofreefwd = iagp->inofreeback = cpu_to_le32(-1);
  		iagp->extfreefwd = iagp->extfreeback = cpu_to_le32(-1);
  		iagp->iagfree = cpu_to_le32(-1);
  		iagp->nfreeinos = 0;
  		iagp->nfreeexts = cpu_to_le32(EXTSPERIAG);
  
  		/* initialize the free inode summary map (free extent
  		 * summary map initialization handled by bzero).
  		 */
  		for (i = 0; i < SMAPSZ; i++)
  			iagp->inosmap[i] = cpu_to_le32(ONES);
  
  		/*
  		 * Write and sync the metapage
  		 */
  		flush_metapage(mp);
  
  		/*
  		 * txCommit(COMMIT_FORCE) will synchronously write address
  		 * index pages and inode after commit in careful update order
  		 * of address index pages (right to left, bottom up);
  		 */
  		iplist[0] = ipimap;
  		rc = txCommit(tid, 1, &iplist[0], COMMIT_FORCE);
  
  		txEnd(tid);
  		mutex_unlock(&JFS_IP(ipimap)->commit_mutex);
  
  		duplicateIXtree(sb, blkno, xlen, &xaddr);
  
  		/* update the next available iag number */
  		imap->im_nextiag += 1;
  
  		/* Add the iag to the iag free list so we don't lose the iag
  		 * if a failure happens now.
  		 */
  		imap->im_freeiag = iagno;
  
  		/* Until we have logredo working, we want the imap inode &
  		 * control page to be up to date.
  		 */
  		diSync(ipimap);
  
  		/* release the inode map lock */
  		IWRITE_UNLOCK(ipimap);
  	}
  
  	/* obtain read lock on map */
  	IREAD_LOCK(ipimap, RDWRLOCK_IMAP);
  
  	/* read the iag */
  	if ((rc = diIAGRead(imap, iagno, &mp))) {
  		IREAD_UNLOCK(ipimap);
  		rc = -EIO;
  		goto out;
  	}
  	iagp = (struct iag *) mp->data;
  
  	/* remove the iag from the iag free list */
  	imap->im_freeiag = le32_to_cpu(iagp->iagfree);
  	iagp->iagfree = cpu_to_le32(-1);
  
  	/* set the return iag number and buffer pointer */
  	*iagnop = iagno;
  	*mpp = mp;
  
        out:
  	/* release the iag free lock */
  	IAGFREE_UNLOCK(imap);
  
  	return (rc);
  }
  
  /*
   * NAME:	diIAGRead()
   *
   * FUNCTION:	get the buffer for the specified iag within a fileset
   *		or aggregate inode map.
   *
   * PARAMETERS:
   *	imap	- pointer to inode map control structure.
   *	iagno	- iag number.
   *	bpp	- point to buffer pointer to be filled in on successful
   *		  exit.
   *
   * SERIALIZATION:
   *	must have read lock on imap inode
   *	(When called by diExtendFS, the filesystem is quiesced, therefore
   *	 the read lock is unnecessary.)
   *
   * RETURN VALUES:
   *	0	- success.
   *	-EIO	- i/o error.
   */
  static int diIAGRead(struct inomap * imap, int iagno, struct metapage ** mpp)
  {
  	struct inode *ipimap = imap->im_ipimap;
  	s64 blkno;
  
  	/* compute the logical block number of the iag. */
  	blkno = IAGTOLBLK(iagno, JFS_SBI(ipimap->i_sb)->l2nbperpage);
  
  	/* read the iag. */
  	*mpp = read_metapage(ipimap, blkno, PSIZE, 0);
  	if (*mpp == NULL) {
  		return -EIO;
  	}
  
  	return (0);
  }
  
  /*
   * NAME:	diFindFree()
   *
   * FUNCTION:	find the first free bit in a word starting at
   *		the specified bit position.
   *
   * PARAMETERS:
   *	word	- word to be examined.
   *	start	- starting bit position.
   *
   * RETURN VALUES:
   *	bit position of first free bit in the word or 32 if
   *	no free bits were found.
   */
  static int diFindFree(u32 word, int start)
  {
  	int bitno;
  	assert(start < 32);
  	/* scan the word for the first free bit. */
  	for (word <<= start, bitno = start; bitno < 32;
  	     bitno++, word <<= 1) {
  		if ((word & HIGHORDER) == 0)
  			break;
  	}
  	return (bitno);
  }
  
  /*
   * NAME:	diUpdatePMap()
   *
   * FUNCTION: Update the persistent map in an IAG for the allocation or
   *	freeing of the specified inode.
   *
   * PRE CONDITIONS: Working map has already been updated for allocate.
   *
   * PARAMETERS:
   *	ipimap	- Incore inode map inode
   *	inum	- Number of inode to mark in permanent map
   *	is_free	- If 'true' indicates inode should be marked freed, otherwise
   *		  indicates inode should be marked allocated.
   *
   * RETURN VALUES:
   *		0 for success
   */
  int
  diUpdatePMap(struct inode *ipimap,
  	     unsigned long inum, bool is_free, struct tblock * tblk)
  {
  	int rc;
  	struct iag *iagp;
  	struct metapage *mp;
  	int iagno, ino, extno, bitno;
  	struct inomap *imap;
  	u32 mask;
  	struct jfs_log *log;
  	int lsn, difft, diffp;
  	unsigned long flags;
  
  	imap = JFS_IP(ipimap)->i_imap;
  	/* get the iag number containing the inode */
  	iagno = INOTOIAG(inum);
  	/* make sure that the iag is contained within the map */
  	if (iagno >= imap->im_nextiag) {
  		jfs_error(ipimap->i_sb,
  			  "diUpdatePMap: the iag is outside the map");
  		return -EIO;
  	}
  	/* read the iag */
  	IREAD_LOCK(ipimap, RDWRLOCK_IMAP);
  	rc = diIAGRead(imap, iagno, &mp);
  	IREAD_UNLOCK(ipimap);
  	if (rc)
  		return (rc);
  	metapage_wait_for_io(mp);
  	iagp = (struct iag *) mp->data;
  	/* get the inode number and extent number of the inode within
  	 * the iag and the inode number within the extent.
  	 */
  	ino = inum & (INOSPERIAG - 1);
  	extno = ino >> L2INOSPEREXT;
  	bitno = ino & (INOSPEREXT - 1);
  	mask = HIGHORDER >> bitno;
  	/*
  	 * mark the inode free in persistent map:
  	 */
  	if (is_free) {
  		/* The inode should have been allocated both in working
  		 * map and in persistent map;
  		 * the inode will be freed from working map at the release
  		 * of last reference release;
  		 */
  		if (!(le32_to_cpu(iagp->wmap[extno]) & mask)) {
  			jfs_error(ipimap->i_sb,
  				  "diUpdatePMap: inode %ld not marked as "
  				  "allocated in wmap!", inum);
  		}
  		if (!(le32_to_cpu(iagp->pmap[extno]) & mask)) {
  			jfs_error(ipimap->i_sb,
  				  "diUpdatePMap: inode %ld not marked as "
  				  "allocated in pmap!", inum);
  		}
  		/* update the bitmap for the extent of the freed inode */
  		iagp->pmap[extno] &= cpu_to_le32(~mask);
  	}
  	/*
  	 * mark the inode allocated in persistent map:
  	 */
  	else {
  		/* The inode should be already allocated in the working map
  		 * and should be free in persistent map;
  		 */
  		if (!(le32_to_cpu(iagp->wmap[extno]) & mask)) {
  			release_metapage(mp);
  			jfs_error(ipimap->i_sb,
  				  "diUpdatePMap: the inode is not allocated in "
  				  "the working map");
  			return -EIO;
  		}
  		if ((le32_to_cpu(iagp->pmap[extno]) & mask) != 0) {
  			release_metapage(mp);
  			jfs_error(ipimap->i_sb,
  				  "diUpdatePMap: the inode is not free in the "
  				  "persistent map");
  			return -EIO;
  		}
  		/* update the bitmap for the extent of the allocated inode */
  		iagp->pmap[extno] |= cpu_to_le32(mask);
  	}
  	/*
  	 * update iag lsn
  	 */
  	lsn = tblk->lsn;
  	log = JFS_SBI(tblk->sb)->log;
  	LOGSYNC_LOCK(log, flags);
  	if (mp->lsn != 0) {
  		/* inherit older/smaller lsn */
  		logdiff(difft, lsn, log);
  		logdiff(diffp, mp->lsn, log);
  		if (difft < diffp) {
  			mp->lsn = lsn;
  			/* move mp after tblock in logsync list */
  			list_move(&mp->synclist, &tblk->synclist);
  		}
  		/* inherit younger/larger clsn */
  		assert(mp->clsn);
  		logdiff(difft, tblk->clsn, log);
  		logdiff(diffp, mp->clsn, log);
  		if (difft > diffp)
  			mp->clsn = tblk->clsn;
  	} else {
  		mp->log = log;
  		mp->lsn = lsn;
  		/* insert mp after tblock in logsync list */
  		log->count++;
  		list_add(&mp->synclist, &tblk->synclist);
  		mp->clsn = tblk->clsn;
  	}
  	LOGSYNC_UNLOCK(log, flags);
  	write_metapage(mp);
  	return (0);
  }
  
  /*
   *	diExtendFS()
   *
   * function: update imap for extendfs();
   *
   * note: AG size has been increased s.t. each k old contiguous AGs are
   * coalesced into a new AG;
   */
  int diExtendFS(struct inode *ipimap, struct inode *ipbmap)
  {
  	int rc, rcx = 0;
  	struct inomap *imap = JFS_IP(ipimap)->i_imap;
  	struct iag *iagp = NULL, *hiagp = NULL;
  	struct bmap *mp = JFS_SBI(ipbmap->i_sb)->bmap;
  	struct metapage *bp, *hbp;
  	int i, n, head;
  	int numinos, xnuminos = 0, xnumfree = 0;
  	s64 agstart;
  
  	jfs_info("diExtendFS: nextiag:%d numinos:%d numfree:%d",
  		   imap->im_nextiag, atomic_read(&imap->im_numinos),
  		   atomic_read(&imap->im_numfree));
  
  	/*
  	 *	reconstruct imap
  	 *
  	 * coalesce contiguous k (newAGSize/oldAGSize) AGs;
  	 * i.e., (AGi, ..., AGj) where i = k*n and j = k*(n+1) - 1 to AGn;
  	 * note: new AG size = old AG size * (2**x).
  	 */
  
  	/* init per AG control information im_agctl[] */
  	for (i = 0; i < MAXAG; i++) {
  		imap->im_agctl[i].inofree = -1;
  		imap->im_agctl[i].extfree = -1;
  		imap->im_agctl[i].numinos = 0;	/* number of backed inodes */
  		imap->im_agctl[i].numfree = 0;	/* number of free backed inodes */
  	}
  
  	/*
  	 *	process each iag page of the map.
  	 *
  	 * rebuild AG Free Inode List, AG Free Inode Extent List;
  	 */
  	for (i = 0; i < imap->im_nextiag; i++) {
  		if ((rc = diIAGRead(imap, i, &bp))) {
  			rcx = rc;
  			continue;
  		}
  		iagp = (struct iag *) bp->data;
  		if (le32_to_cpu(iagp->iagnum) != i) {
  			release_metapage(bp);
  			jfs_error(ipimap->i_sb,
  				  "diExtendFs: unexpected value of iagnum");
  			return -EIO;
  		}
  
  		/* leave free iag in the free iag list */
  		if (iagp->nfreeexts == cpu_to_le32(EXTSPERIAG)) {
  			release_metapage(bp);
  			continue;
  		}
  
  		agstart = le64_to_cpu(iagp->agstart);
  		n = agstart >> mp->db_agl2size;
  		iagp->agstart = cpu_to_le64((s64)n << mp->db_agl2size);
  
  		/* compute backed inodes */
  		numinos = (EXTSPERIAG - le32_to_cpu(iagp->nfreeexts))
  		    << L2INOSPEREXT;
  		if (numinos > 0) {
  			/* merge AG backed inodes */
  			imap->im_agctl[n].numinos += numinos;
  			xnuminos += numinos;
  		}
  
  		/* if any backed free inodes, insert at AG free inode list */
  		if ((int) le32_to_cpu(iagp->nfreeinos) > 0) {
  			if ((head = imap->im_agctl[n].inofree) == -1) {
  				iagp->inofreefwd = cpu_to_le32(-1);
  				iagp->inofreeback = cpu_to_le32(-1);
  			} else {
  				if ((rc = diIAGRead(imap, head, &hbp))) {
  					rcx = rc;
  					goto nextiag;
  				}
  				hiagp = (struct iag *) hbp->data;
  				hiagp->inofreeback = iagp->iagnum;
  				iagp->inofreefwd = cpu_to_le32(head);
  				iagp->inofreeback = cpu_to_le32(-1);
  				write_metapage(hbp);
  			}
  
  			imap->im_agctl[n].inofree =
  			    le32_to_cpu(iagp->iagnum);
  
  			/* merge AG backed free inodes */
  			imap->im_agctl[n].numfree +=
  			    le32_to_cpu(iagp->nfreeinos);
  			xnumfree += le32_to_cpu(iagp->nfreeinos);
  		}
  
  		/* if any free extents, insert at AG free extent list */
  		if (le32_to_cpu(iagp->nfreeexts) > 0) {
  			if ((head = imap->im_agctl[n].extfree) == -1) {
  				iagp->extfreefwd = cpu_to_le32(-1);
  				iagp->extfreeback = cpu_to_le32(-1);
  			} else {
  				if ((rc = diIAGRead(imap, head, &hbp))) {
  					rcx = rc;
  					goto nextiag;
  				}
  				hiagp = (struct iag *) hbp->data;
  				hiagp->extfreeback = iagp->iagnum;
  				iagp->extfreefwd = cpu_to_le32(head);
  				iagp->extfreeback = cpu_to_le32(-1);
  				write_metapage(hbp);
  			}
  
  			imap->im_agctl[n].extfree =
  			    le32_to_cpu(iagp->iagnum);
  		}
  
  	      nextiag:
  		write_metapage(bp);
  	}
  
  	if (xnuminos != atomic_read(&imap->im_numinos) ||
  	    xnumfree != atomic_read(&imap->im_numfree)) {
  		jfs_error(ipimap->i_sb,
  			  "diExtendFs: numinos or numfree incorrect");
  		return -EIO;
  	}
  
  	return rcx;
  }
  
  
  /*
   *	duplicateIXtree()
   *
   * serialization: IWRITE_LOCK held on entry/exit
   *
   * note: shadow page with regular inode (rel.2);
   */
  static void duplicateIXtree(struct super_block *sb, s64 blkno,
  			    int xlen, s64 *xaddr)
  {
  	struct jfs_superblock *j_sb;
  	struct buffer_head *bh;
  	struct inode *ip;
  	tid_t tid;
  
  	/* if AIT2 ipmap2 is bad, do not try to update it */
  	if (JFS_SBI(sb)->mntflag & JFS_BAD_SAIT)	/* s_flag */
  		return;
  	ip = diReadSpecial(sb, FILESYSTEM_I, 1);
  	if (ip == NULL) {
  		JFS_SBI(sb)->mntflag |= JFS_BAD_SAIT;
  		if (readSuper(sb, &bh))
  			return;
  		j_sb = (struct jfs_superblock *)bh->b_data;
  		j_sb->s_flag |= cpu_to_le32(JFS_BAD_SAIT);
  
  		mark_buffer_dirty(bh);
  		sync_dirty_buffer(bh);
  		brelse(bh);
  		return;
  	}
  
  	/* start transaction */
  	tid = txBegin(sb, COMMIT_FORCE);
  	/* update the inode map addressing structure to point to it */
  	if (xtInsert(tid, ip, 0, blkno, xlen, xaddr, 0)) {
  		JFS_SBI(sb)->mntflag |= JFS_BAD_SAIT;
  		txAbort(tid, 1);
  		goto cleanup;
  
  	}
  	/* update the inode map's inode to reflect the extension */
  	ip->i_size += PSIZE;
  	inode_add_bytes(ip, PSIZE);
  	txCommit(tid, 1, &ip, COMMIT_FORCE);
        cleanup:
  	txEnd(tid);
  	diFreeSpecial(ip);
  }
  
  /*
   * NAME:	copy_from_dinode()
   *
   * FUNCTION:	Copies inode info from disk inode to in-memory inode
   *
   * RETURN VALUES:
   *	0	- success
   *	-ENOMEM	- insufficient memory
   */
  static int copy_from_dinode(struct dinode * dip, struct inode *ip)
  {
  	struct jfs_inode_info *jfs_ip = JFS_IP(ip);
  	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
  
  	jfs_ip->fileset = le32_to_cpu(dip->di_fileset);
  	jfs_ip->mode2 = le32_to_cpu(dip->di_mode);
  	jfs_set_inode_flags(ip);
  
  	ip->i_mode = le32_to_cpu(dip->di_mode) & 0xffff;
  	if (sbi->umask != -1) {
  		ip->i_mode = (ip->i_mode & ~0777) | (0777 & ~sbi->umask);
  		/* For directories, add x permission if r is allowed by umask */
  		if (S_ISDIR(ip->i_mode)) {
  			if (ip->i_mode & 0400)
  				ip->i_mode |= 0100;
  			if (ip->i_mode & 0040)
  				ip->i_mode |= 0010;
  			if (ip->i_mode & 0004)
  				ip->i_mode |= 0001;
  		}
  	}
  	ip->i_nlink = le32_to_cpu(dip->di_nlink);
  
  	jfs_ip->saved_uid = le32_to_cpu(dip->di_uid);
  	if (sbi->uid == -1)
  		ip->i_uid = jfs_ip->saved_uid;
  	else {
  		ip->i_uid = sbi->uid;
  	}
  
  	jfs_ip->saved_gid = le32_to_cpu(dip->di_gid);
  	if (sbi->gid == -1)
  		ip->i_gid = jfs_ip->saved_gid;
  	else {
  		ip->i_gid = sbi->gid;
  	}
  
  	ip->i_size = le64_to_cpu(dip->di_size);
  	ip->i_atime.tv_sec = le32_to_cpu(dip->di_atime.tv_sec);
  	ip->i_atime.tv_nsec = le32_to_cpu(dip->di_atime.tv_nsec);
  	ip->i_mtime.tv_sec = le32_to_cpu(dip->di_mtime.tv_sec);
  	ip->i_mtime.tv_nsec = le32_to_cpu(dip->di_mtime.tv_nsec);
  	ip->i_ctime.tv_sec = le32_to_cpu(dip->di_ctime.tv_sec);
  	ip->i_ctime.tv_nsec = le32_to_cpu(dip->di_ctime.tv_nsec);
  	ip->i_blocks = LBLK2PBLK(ip->i_sb, le64_to_cpu(dip->di_nblocks));
  	ip->i_generation = le32_to_cpu(dip->di_gen);
  
  	jfs_ip->ixpxd = dip->di_ixpxd;	/* in-memory pxd's are little-endian */
  	jfs_ip->acl = dip->di_acl;	/* as are dxd's */
  	jfs_ip->ea = dip->di_ea;
  	jfs_ip->next_index = le32_to_cpu(dip->di_next_index);
  	jfs_ip->otime = le32_to_cpu(dip->di_otime.tv_sec);
  	jfs_ip->acltype = le32_to_cpu(dip->di_acltype);
  
  	if (S_ISCHR(ip->i_mode) || S_ISBLK(ip->i_mode)) {
  		jfs_ip->dev = le32_to_cpu(dip->di_rdev);
  		ip->i_rdev = new_decode_dev(jfs_ip->dev);
  	}
  
  	if (S_ISDIR(ip->i_mode)) {
  		memcpy(&jfs_ip->i_dirtable, &dip->di_dirtable, 384);
  	} else if (S_ISREG(ip->i_mode) || S_ISLNK(ip->i_mode)) {
  		memcpy(&jfs_ip->i_xtroot, &dip->di_xtroot, 288);
  	} else
  		memcpy(&jfs_ip->i_inline_ea, &dip->di_inlineea, 128);
  
  	/* Zero the in-memory-only stuff */
  	jfs_ip->cflag = 0;
  	jfs_ip->btindex = 0;
  	jfs_ip->btorder = 0;
  	jfs_ip->bxflag = 0;
  	jfs_ip->blid = 0;
  	jfs_ip->atlhead = 0;
  	jfs_ip->atltail = 0;
  	jfs_ip->xtlid = 0;
  	return (0);
  }
  
  /*
   * NAME:	copy_to_dinode()
   *
   * FUNCTION:	Copies inode info from in-memory inode to disk inode
   */
  static void copy_to_dinode(struct dinode * dip, struct inode *ip)
  {
  	struct jfs_inode_info *jfs_ip = JFS_IP(ip);
  	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
  
  	dip->di_fileset = cpu_to_le32(jfs_ip->fileset);
  	dip->di_inostamp = cpu_to_le32(sbi->inostamp);
  	dip->di_number = cpu_to_le32(ip->i_ino);
  	dip->di_gen = cpu_to_le32(ip->i_generation);
  	dip->di_size = cpu_to_le64(ip->i_size);
  	dip->di_nblocks = cpu_to_le64(PBLK2LBLK(ip->i_sb, ip->i_blocks));
  	dip->di_nlink = cpu_to_le32(ip->i_nlink);
  	if (sbi->uid == -1)
  		dip->di_uid = cpu_to_le32(ip->i_uid);
  	else
  		dip->di_uid = cpu_to_le32(jfs_ip->saved_uid);
  	if (sbi->gid == -1)
  		dip->di_gid = cpu_to_le32(ip->i_gid);
  	else
  		dip->di_gid = cpu_to_le32(jfs_ip->saved_gid);
  	jfs_get_inode_flags(jfs_ip);
  	/*
  	 * mode2 is only needed for storing the higher order bits.
  	 * Trust i_mode for the lower order ones
  	 */
  	if (sbi->umask == -1)
  		dip->di_mode = cpu_to_le32((jfs_ip->mode2 & 0xffff0000) |
  					   ip->i_mode);
  	else /* Leave the original permissions alone */
  		dip->di_mode = cpu_to_le32(jfs_ip->mode2);
  
  	dip->di_atime.tv_sec = cpu_to_le32(ip->i_atime.tv_sec);
  	dip->di_atime.tv_nsec = cpu_to_le32(ip->i_atime.tv_nsec);
  	dip->di_ctime.tv_sec = cpu_to_le32(ip->i_ctime.tv_sec);
  	dip->di_ctime.tv_nsec = cpu_to_le32(ip->i_ctime.tv_nsec);
  	dip->di_mtime.tv_sec = cpu_to_le32(ip->i_mtime.tv_sec);
  	dip->di_mtime.tv_nsec = cpu_to_le32(ip->i_mtime.tv_nsec);
  	dip->di_ixpxd = jfs_ip->ixpxd;	/* in-memory pxd's are little-endian */
  	dip->di_acl = jfs_ip->acl;	/* as are dxd's */
  	dip->di_ea = jfs_ip->ea;
  	dip->di_next_index = cpu_to_le32(jfs_ip->next_index);
  	dip->di_otime.tv_sec = cpu_to_le32(jfs_ip->otime);
  	dip->di_otime.tv_nsec = 0;
  	dip->di_acltype = cpu_to_le32(jfs_ip->acltype);
  	if (S_ISCHR(ip->i_mode) || S_ISBLK(ip->i_mode))
  		dip->di_rdev = cpu_to_le32(jfs_ip->dev);
  }
  