text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   * All Rights Reserved.
   */
  #include "xfs.h"
  #include "xfs_fs.h"
  #include "xfs_shared.h"
  #include "xfs_format.h"
  #include "xfs_log_format.h"
  #include "xfs_trans_resv.h"
  #include "xfs_bit.h"
  #include "xfs_sb.h"
  #include "xfs_mount.h"
  #include "xfs_defer.h"
  #include "xfs_da_format.h"
  #include "xfs_da_btree.h"
  #include "xfs_dir2.h"
  #include "xfs_inode.h"
  #include "xfs_btree.h"
  #include "xfs_trans.h"
  #include "xfs_inode_item.h"
  #include "xfs_extfree_item.h"
  #include "xfs_alloc.h"
  #include "xfs_bmap.h"
  #include "xfs_bmap_util.h"
  #include "xfs_bmap_btree.h"
  #include "xfs_rtalloc.h"
  #include "xfs_errortag.h"
  #include "xfs_error.h"
  #include "xfs_quota.h"
  #include "xfs_trans_space.h"
  #include "xfs_buf_item.h"
  #include "xfs_trace.h"
  #include "xfs_symlink.h"
  #include "xfs_attr_leaf.h"
  #include "xfs_filestream.h"
  #include "xfs_rmap.h"
  #include "xfs_ag_resv.h"
  #include "xfs_refcount.h"
  #include "xfs_icache.h"
  
  
  kmem_zone_t		*xfs_bmap_free_item_zone;
  
  /*
   * Miscellaneous helper functions
   */
  
  /*
   * Compute and fill in the value of the maximum depth of a bmap btree
   * in this filesystem.  Done once, during mount.
   */
  void
  xfs_bmap_compute_maxlevels(
  	xfs_mount_t	*mp,		/* file system mount structure */
  	int		whichfork)	/* data or attr fork */
  {
  	int		level;		/* btree level */
  	uint		maxblocks;	/* max blocks at this level */
  	uint		maxleafents;	/* max leaf entries possible */
  	int		maxrootrecs;	/* max records in root block */
  	int		minleafrecs;	/* min records in leaf block */
  	int		minnoderecs;	/* min records in node block */
  	int		sz;		/* root block size */
  
  	/*
  	 * The maximum number of extents in a file, hence the maximum
  	 * number of leaf entries, is controlled by the type of di_nextents
  	 * (a signed 32-bit number, xfs_extnum_t), or by di_anextents
  	 * (a signed 16-bit number, xfs_aextnum_t).
  	 *
  	 * Note that we can no longer assume that if we are in ATTR1 that
  	 * the fork offset of all the inodes will be
  	 * (xfs_default_attroffset(ip) >> 3) because we could have mounted
  	 * with ATTR2 and then mounted back with ATTR1, keeping the
  	 * di_forkoff's fixed but probably at various positions. Therefore,
  	 * for both ATTR1 and ATTR2 we have to assume the worst case scenario
  	 * of a minimum size available.
  	 */
  	if (whichfork == XFS_DATA_FORK) {
  		maxleafents = MAXEXTNUM;
  		sz = XFS_BMDR_SPACE_CALC(MINDBTPTRS);
  	} else {
  		maxleafents = MAXAEXTNUM;
  		sz = XFS_BMDR_SPACE_CALC(MINABTPTRS);
  	}
  	maxrootrecs = xfs_bmdr_maxrecs(sz, 0);
  	minleafrecs = mp->m_bmap_dmnr[0];
  	minnoderecs = mp->m_bmap_dmnr[1];
  	maxblocks = (maxleafents + minleafrecs - 1) / minleafrecs;
  	for (level = 1; maxblocks > 1; level++) {
  		if (maxblocks <= maxrootrecs)
  			maxblocks = 1;
  		else
  			maxblocks = (maxblocks + minnoderecs - 1) / minnoderecs;
  	}
  	mp->m_bm_maxlevels[whichfork] = level;
  }
  
  STATIC int				/* error */
  xfs_bmbt_lookup_eq(
  	struct xfs_btree_cur	*cur,
  	struct xfs_bmbt_irec	*irec,
  	int			*stat)	/* success/failure */
  {
  	cur->bc_rec.b = *irec;
  	return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
  }
  
  STATIC int				/* error */
  xfs_bmbt_lookup_first(
  	struct xfs_btree_cur	*cur,
  	int			*stat)	/* success/failure */
  {
  	cur->bc_rec.b.br_startoff = 0;
  	cur->bc_rec.b.br_startblock = 0;
  	cur->bc_rec.b.br_blockcount = 0;
  	return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
  }
  
  /*
   * Check if the inode needs to be converted to btree format.
   */
  static inline bool xfs_bmap_needs_btree(struct xfs_inode *ip, int whichfork)
  {
  	return whichfork != XFS_COW_FORK &&
  		XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_EXTENTS &&
  		XFS_IFORK_NEXTENTS(ip, whichfork) >
  			XFS_IFORK_MAXEXT(ip, whichfork);
  }
  
  /*
   * Check if the inode should be converted to extent format.
   */
  static inline bool xfs_bmap_wants_extents(struct xfs_inode *ip, int whichfork)
  {
  	return whichfork != XFS_COW_FORK &&
  		XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_BTREE &&
  		XFS_IFORK_NEXTENTS(ip, whichfork) <=
  			XFS_IFORK_MAXEXT(ip, whichfork);
  }
  
  /*
   * Update the record referred to by cur to the value given by irec
   * This either works (return 0) or gets an EFSCORRUPTED error.
   */
  STATIC int
  xfs_bmbt_update(
  	struct xfs_btree_cur	*cur,
  	struct xfs_bmbt_irec	*irec)
  {
  	union xfs_btree_rec	rec;
  
  	xfs_bmbt_disk_set_all(&rec.bmbt, irec);
  	return xfs_btree_update(cur, &rec);
  }
  
  /*
   * Compute the worst-case number of indirect blocks that will be used
   * for ip's delayed extent of length "len".
   */
  STATIC xfs_filblks_t
  xfs_bmap_worst_indlen(
  	xfs_inode_t	*ip,		/* incore inode pointer */
  	xfs_filblks_t	len)		/* delayed extent length */
  {
  	int		level;		/* btree level number */
  	int		maxrecs;	/* maximum record count at this level */
  	xfs_mount_t	*mp;		/* mount structure */
  	xfs_filblks_t	rval;		/* return value */
  
  	mp = ip->i_mount;
  	maxrecs = mp->m_bmap_dmxr[0];
  	for (level = 0, rval = 0;
  	     level < XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK);
  	     level++) {
  		len += maxrecs - 1;
  		do_div(len, maxrecs);
  		rval += len;
  		if (len == 1)
  			return rval + XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK) -
  				level - 1;
  		if (level == 0)
  			maxrecs = mp->m_bmap_dmxr[1];
  	}
  	return rval;
  }
  
  /*
   * Calculate the default attribute fork offset for newly created inodes.
   */
  uint
  xfs_default_attroffset(
  	struct xfs_inode	*ip)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	uint			offset;
  
  	if (mp->m_sb.sb_inodesize == 256) {
  		offset = XFS_LITINO(mp, ip->i_d.di_version) -
  				XFS_BMDR_SPACE_CALC(MINABTPTRS);
  	} else {
  		offset = XFS_BMDR_SPACE_CALC(6 * MINABTPTRS);
  	}
  
  	ASSERT(offset < XFS_LITINO(mp, ip->i_d.di_version));
  	return offset;
  }
  
  /*
   * Helper routine to reset inode di_forkoff field when switching
   * attribute fork from local to extent format - we reset it where
   * possible to make space available for inline data fork extents.
   */
  STATIC void
  xfs_bmap_forkoff_reset(
  	xfs_inode_t	*ip,
  	int		whichfork)
  {
  	if (whichfork == XFS_ATTR_FORK &&
  	    ip->i_d.di_format != XFS_DINODE_FMT_DEV &&
  	    ip->i_d.di_format != XFS_DINODE_FMT_BTREE) {
  		uint	dfl_forkoff = xfs_default_attroffset(ip) >> 3;
  
  		if (dfl_forkoff > ip->i_d.di_forkoff)
  			ip->i_d.di_forkoff = dfl_forkoff;
  	}
  }
  
  #ifdef DEBUG
  STATIC struct xfs_buf *
  xfs_bmap_get_bp(
  	struct xfs_btree_cur	*cur,
  	xfs_fsblock_t		bno)
  {
  	struct xfs_log_item	*lip;
  	int			i;
  
  	if (!cur)
  		return NULL;
  
  	for (i = 0; i < XFS_BTREE_MAXLEVELS; i++) {
  		if (!cur->bc_bufs[i])
  			break;
  		if (XFS_BUF_ADDR(cur->bc_bufs[i]) == bno)
  			return cur->bc_bufs[i];
  	}
  
  	/* Chase down all the log items to see if the bp is there */
  	list_for_each_entry(lip, &cur->bc_tp->t_items, li_trans) {
  		struct xfs_buf_log_item	*bip = (struct xfs_buf_log_item *)lip;
  
  		if (bip->bli_item.li_type == XFS_LI_BUF &&
  		    XFS_BUF_ADDR(bip->bli_buf) == bno)
  			return bip->bli_buf;
  	}
  
  	return NULL;
  }
  
  STATIC void
  xfs_check_block(
  	struct xfs_btree_block	*block,
  	xfs_mount_t		*mp,
  	int			root,
  	short			sz)
  {
  	int			i, j, dmxr;
  	__be64			*pp, *thispa;	/* pointer to block address */
  	xfs_bmbt_key_t		*prevp, *keyp;
  
  	ASSERT(be16_to_cpu(block->bb_level) > 0);
  
  	prevp = NULL;
  	for( i = 1; i <= xfs_btree_get_numrecs(block); i++) {
  		dmxr = mp->m_bmap_dmxr[0];
  		keyp = XFS_BMBT_KEY_ADDR(mp, block, i);
  
  		if (prevp) {
  			ASSERT(be64_to_cpu(prevp->br_startoff) <
  			       be64_to_cpu(keyp->br_startoff));
  		}
  		prevp = keyp;
  
  		/*
  		 * Compare the block numbers to see if there are dups.
  		 */
  		if (root)
  			pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, i, sz);
  		else
  			pp = XFS_BMBT_PTR_ADDR(mp, block, i, dmxr);
  
  		for (j = i+1; j <= be16_to_cpu(block->bb_numrecs); j++) {
  			if (root)
  				thispa = XFS_BMAP_BROOT_PTR_ADDR(mp, block, j, sz);
  			else
  				thispa = XFS_BMBT_PTR_ADDR(mp, block, j, dmxr);
  			if (*thispa == *pp) {
  				xfs_warn(mp, "%s: thispa(%d) == pp(%d) %Ld",
  					__func__, j, i,
  					(unsigned long long)be64_to_cpu(*thispa));
  				xfs_err(mp, "%s: ptrs are equal in node\n",
  					__func__);
  				xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
  			}
  		}
  	}
  }
  
  /*
   * Check that the extents for the inode ip are in the right order in all
   * btree leaves. THis becomes prohibitively expensive for large extent count
   * files, so don't bother with inodes that have more than 10,000 extents in
   * them. The btree record ordering checks will still be done, so for such large
   * bmapbt constructs that is going to catch most corruptions.
   */
  STATIC void
  xfs_bmap_check_leaf_extents(
  	xfs_btree_cur_t		*cur,	/* btree cursor or null */
  	xfs_inode_t		*ip,		/* incore inode pointer */
  	int			whichfork)	/* data or attr fork */
  {
  	struct xfs_btree_block	*block;	/* current btree block */
  	xfs_fsblock_t		bno;	/* block # of "block" */
  	xfs_buf_t		*bp;	/* buffer for "block" */
  	int			error;	/* error return value */
  	xfs_extnum_t		i=0, j;	/* index into the extents list */
  	struct xfs_ifork	*ifp;	/* fork structure */
  	int			level;	/* btree level, for checking */
  	xfs_mount_t		*mp;	/* file system mount structure */
  	__be64			*pp;	/* pointer to block address */
  	xfs_bmbt_rec_t		*ep;	/* pointer to current extent */
  	xfs_bmbt_rec_t		last = {0, 0}; /* last extent in prev block */
  	xfs_bmbt_rec_t		*nextp;	/* pointer to next extent */
  	int			bp_release = 0;
  
  	if (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE) {
  		return;
  	}
  
  	/* skip large extent count inodes */
  	if (ip->i_d.di_nextents > 10000)
  		return;
  
  	bno = NULLFSBLOCK;
  	mp = ip->i_mount;
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	block = ifp->if_broot;
  	/*
  	 * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out.
  	 */
  	level = be16_to_cpu(block->bb_level);
  	ASSERT(level > 0);
  	xfs_check_block(block, mp, 1, ifp->if_broot_bytes);
  	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes);
  	bno = be64_to_cpu(*pp);
  
  	ASSERT(bno != NULLFSBLOCK);
  	ASSERT(XFS_FSB_TO_AGNO(mp, bno) < mp->m_sb.sb_agcount);
  	ASSERT(XFS_FSB_TO_AGBNO(mp, bno) < mp->m_sb.sb_agblocks);
  
  	/*
  	 * Go down the tree until leaf level is reached, following the first
  	 * pointer (leftmost) at each level.
  	 */
  	while (level-- > 0) {
  		/* See if buf is in cur first */
  		bp_release = 0;
  		bp = xfs_bmap_get_bp(cur, XFS_FSB_TO_DADDR(mp, bno));
  		if (!bp) {
  			bp_release = 1;
  			error = xfs_btree_read_bufl(mp, NULL, bno, 0, &bp,
  						XFS_BMAP_BTREE_REF,
  						&xfs_bmbt_buf_ops);
  			if (error)
  				goto error_norelse;
  		}
  		block = XFS_BUF_TO_BLOCK(bp);
  		if (level == 0)
  			break;
  
  		/*
  		 * Check this block for basic sanity (increasing keys and
  		 * no duplicate blocks).
  		 */
  
  		xfs_check_block(block, mp, 0, 0);
  		pp = XFS_BMBT_PTR_ADDR(mp, block, 1, mp->m_bmap_dmxr[1]);
  		bno = be64_to_cpu(*pp);
  		XFS_WANT_CORRUPTED_GOTO(mp,
  					xfs_verify_fsbno(mp, bno), error0);
  		if (bp_release) {
  			bp_release = 0;
  			xfs_trans_brelse(NULL, bp);
  		}
  	}
  
  	/*
  	 * Here with bp and block set to the leftmost leaf node in the tree.
  	 */
  	i = 0;
  
  	/*
  	 * Loop over all leaf nodes checking that all extents are in the right order.
  	 */
  	for (;;) {
  		xfs_fsblock_t	nextbno;
  		xfs_extnum_t	num_recs;
  
  
  		num_recs = xfs_btree_get_numrecs(block);
  
  		/*
  		 * Read-ahead the next leaf block, if any.
  		 */
  
  		nextbno = be64_to_cpu(block->bb_u.l.bb_rightsib);
  
  		/*
  		 * Check all the extents to make sure they are OK.
  		 * If we had a previous block, the last entry should
  		 * conform with the first entry in this one.
  		 */
  
  		ep = XFS_BMBT_REC_ADDR(mp, block, 1);
  		if (i) {
  			ASSERT(xfs_bmbt_disk_get_startoff(&last) +
  			       xfs_bmbt_disk_get_blockcount(&last) <=
  			       xfs_bmbt_disk_get_startoff(ep));
  		}
  		for (j = 1; j < num_recs; j++) {
  			nextp = XFS_BMBT_REC_ADDR(mp, block, j + 1);
  			ASSERT(xfs_bmbt_disk_get_startoff(ep) +
  			       xfs_bmbt_disk_get_blockcount(ep) <=
  			       xfs_bmbt_disk_get_startoff(nextp));
  			ep = nextp;
  		}
  
  		last = *ep;
  		i += num_recs;
  		if (bp_release) {
  			bp_release = 0;
  			xfs_trans_brelse(NULL, bp);
  		}
  		bno = nextbno;
  		/*
  		 * If we've reached the end, stop.
  		 */
  		if (bno == NULLFSBLOCK)
  			break;
  
  		bp_release = 0;
  		bp = xfs_bmap_get_bp(cur, XFS_FSB_TO_DADDR(mp, bno));
  		if (!bp) {
  			bp_release = 1;
  			error = xfs_btree_read_bufl(mp, NULL, bno, 0, &bp,
  						XFS_BMAP_BTREE_REF,
  						&xfs_bmbt_buf_ops);
  			if (error)
  				goto error_norelse;
  		}
  		block = XFS_BUF_TO_BLOCK(bp);
  	}
  
  	return;
  
  error0:
  	xfs_warn(mp, "%s: at error0", __func__);
  	if (bp_release)
  		xfs_trans_brelse(NULL, bp);
  error_norelse:
  	xfs_warn(mp, "%s: BAD after btree leaves for %d extents",
  		__func__, i);
  	xfs_err(mp, "%s: CORRUPTED BTREE OR SOMETHING", __func__);
  	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
  	return;
  }
  
  /*
   * Validate that the bmbt_irecs being returned from bmapi are valid
   * given the caller's original parameters.  Specifically check the
   * ranges of the returned irecs to ensure that they only extend beyond
   * the given parameters if the XFS_BMAPI_ENTIRE flag was set.
   */
  STATIC void
  xfs_bmap_validate_ret(
  	xfs_fileoff_t		bno,
  	xfs_filblks_t		len,
  	int			flags,
  	xfs_bmbt_irec_t		*mval,
  	int			nmap,
  	int			ret_nmap)
  {
  	int			i;		/* index to map values */
  
  	ASSERT(ret_nmap <= nmap);
  
  	for (i = 0; i < ret_nmap; i++) {
  		ASSERT(mval[i].br_blockcount > 0);
  		if (!(flags & XFS_BMAPI_ENTIRE)) {
  			ASSERT(mval[i].br_startoff >= bno);
  			ASSERT(mval[i].br_blockcount <= len);
  			ASSERT(mval[i].br_startoff + mval[i].br_blockcount <=
  			       bno + len);
  		} else {
  			ASSERT(mval[i].br_startoff < bno + len);
  			ASSERT(mval[i].br_startoff + mval[i].br_blockcount >
  			       bno);
  		}
  		ASSERT(i == 0 ||
  		       mval[i - 1].br_startoff + mval[i - 1].br_blockcount ==
  		       mval[i].br_startoff);
  		ASSERT(mval[i].br_startblock != DELAYSTARTBLOCK &&
  		       mval[i].br_startblock != HOLESTARTBLOCK);
  		ASSERT(mval[i].br_state == XFS_EXT_NORM ||
  		       mval[i].br_state == XFS_EXT_UNWRITTEN);
  	}
  }
  
  #else
  #define xfs_bmap_check_leaf_extents(cur, ip, whichfork)		do { } while (0)
  #define	xfs_bmap_validate_ret(bno,len,flags,mval,onmap,nmap)	do { } while (0)
  #endif /* DEBUG */
  
  /*
   * bmap free list manipulation functions
   */
  
  /*
   * Add the extent to the list of extents to be free at transaction end.
   * The list is maintained sorted (by block number).
   */
  void
  __xfs_bmap_add_free(
  	struct xfs_trans		*tp,
  	xfs_fsblock_t			bno,
  	xfs_filblks_t			len,
  	const struct xfs_owner_info	*oinfo,
  	bool				skip_discard)
  {
  	struct xfs_extent_free_item	*new;		/* new element */
  #ifdef DEBUG
  	struct xfs_mount		*mp = tp->t_mountp;
  	xfs_agnumber_t			agno;
  	xfs_agblock_t			agbno;
  
  	ASSERT(bno != NULLFSBLOCK);
  	ASSERT(len > 0);
  	ASSERT(len <= MAXEXTLEN);
  	ASSERT(!isnullstartblock(bno));
  	agno = XFS_FSB_TO_AGNO(mp, bno);
  	agbno = XFS_FSB_TO_AGBNO(mp, bno);
  	ASSERT(agno < mp->m_sb.sb_agcount);
  	ASSERT(agbno < mp->m_sb.sb_agblocks);
  	ASSERT(len < mp->m_sb.sb_agblocks);
  	ASSERT(agbno + len <= mp->m_sb.sb_agblocks);
  #endif
  	ASSERT(xfs_bmap_free_item_zone != NULL);
  
  	new = kmem_zone_alloc(xfs_bmap_free_item_zone, KM_SLEEP);
  	new->xefi_startblock = bno;
  	new->xefi_blockcount = (xfs_extlen_t)len;
  	if (oinfo)
  		new->xefi_oinfo = *oinfo;
  	else
  		new->xefi_oinfo = XFS_RMAP_OINFO_SKIP_UPDATE;
  	new->xefi_skip_discard = skip_discard;
  	trace_xfs_bmap_free_defer(tp->t_mountp,
  			XFS_FSB_TO_AGNO(tp->t_mountp, bno), 0,
  			XFS_FSB_TO_AGBNO(tp->t_mountp, bno), len);
  	xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_FREE, &new->xefi_list);
  }
  
  /*
   * Inode fork format manipulation functions
   */
  
  /*
   * Convert the inode format to extent format if it currently is in btree format,
   * but the extent list is small enough that it fits into the extent format.
   *
   * Since the extents are already in-core, all we have to do is give up the space
   * for the btree root and pitch the leaf block.
   */
  STATIC int				/* error */
  xfs_bmap_btree_to_extents(
  	struct xfs_trans	*tp,	/* transaction pointer */
  	struct xfs_inode	*ip,	/* incore inode pointer */
  	struct xfs_btree_cur	*cur,	/* btree cursor */
  	int			*logflagsp, /* inode logging flags */
  	int			whichfork)  /* data or attr fork */
  {
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_btree_block	*rblock = ifp->if_broot;
  	struct xfs_btree_block	*cblock;/* child btree block */
  	xfs_fsblock_t		cbno;	/* child block number */
  	xfs_buf_t		*cbp;	/* child block's buffer */
  	int			error;	/* error return value */
  	__be64			*pp;	/* ptr to block address */
  	struct xfs_owner_info	oinfo;
  
  	/* check if we actually need the extent format first: */
  	if (!xfs_bmap_wants_extents(ip, whichfork))
  		return 0;
  
  	ASSERT(cur);
  	ASSERT(whichfork != XFS_COW_FORK);
  	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
  	ASSERT(XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_BTREE);
  	ASSERT(be16_to_cpu(rblock->bb_level) == 1);
  	ASSERT(be16_to_cpu(rblock->bb_numrecs) == 1);
  	ASSERT(xfs_bmbt_maxrecs(mp, ifp->if_broot_bytes, 0) == 1);
  
  	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, rblock, 1, ifp->if_broot_bytes);
  	cbno = be64_to_cpu(*pp);
  #ifdef DEBUG
  	XFS_WANT_CORRUPTED_RETURN(cur->bc_mp,
  			xfs_btree_check_lptr(cur, cbno, 1));
  #endif
  	error = xfs_btree_read_bufl(mp, tp, cbno, 0, &cbp, XFS_BMAP_BTREE_REF,
  				&xfs_bmbt_buf_ops);
  	if (error)
  		return error;
  	cblock = XFS_BUF_TO_BLOCK(cbp);
  	if ((error = xfs_btree_check_block(cur, cblock, 0, cbp)))
  		return error;
  	xfs_rmap_ino_bmbt_owner(&oinfo, ip->i_ino, whichfork);
  	xfs_bmap_add_free(cur->bc_tp, cbno, 1, &oinfo);
  	ip->i_d.di_nblocks--;
  	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L);
  	xfs_trans_binval(tp, cbp);
  	if (cur->bc_bufs[0] == cbp)
  		cur->bc_bufs[0] = NULL;
  	xfs_iroot_realloc(ip, -1, whichfork);
  	ASSERT(ifp->if_broot == NULL);
  	ASSERT((ifp->if_flags & XFS_IFBROOT) == 0);
  	XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_EXTENTS);
  	*logflagsp |= XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
  	return 0;
  }
  
  /*
   * Convert an extents-format file into a btree-format file.
   * The new file will have a root block (in the inode) and a single child block.
   */
  STATIC int					/* error */
  xfs_bmap_extents_to_btree(
  	struct xfs_trans	*tp,		/* transaction pointer */
  	struct xfs_inode	*ip,		/* incore inode pointer */
  	struct xfs_btree_cur	**curp,		/* cursor returned to caller */
  	int			wasdel,		/* converting a delayed alloc */
  	int			*logflagsp,	/* inode logging flags */
  	int			whichfork)	/* data or attr fork */
  {
  	struct xfs_btree_block	*ablock;	/* allocated (child) bt block */
  	struct xfs_buf		*abp;		/* buffer for ablock */
  	struct xfs_alloc_arg	args;		/* allocation arguments */
  	struct xfs_bmbt_rec	*arp;		/* child record pointer */
  	struct xfs_btree_block	*block;		/* btree root block */
  	struct xfs_btree_cur	*cur;		/* bmap btree cursor */
  	int			error;		/* error return value */
  	struct xfs_ifork	*ifp;		/* inode fork pointer */
  	struct xfs_bmbt_key	*kp;		/* root block key pointer */
  	struct xfs_mount	*mp;		/* mount structure */
  	xfs_bmbt_ptr_t		*pp;		/* root block address pointer */
  	struct xfs_iext_cursor	icur;
  	struct xfs_bmbt_irec	rec;
  	xfs_extnum_t		cnt = 0;
  
  	mp = ip->i_mount;
  	ASSERT(whichfork != XFS_COW_FORK);
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	ASSERT(XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_EXTENTS);
  
  	/*
  	 * Make space in the inode incore. This needs to be undone if we fail
  	 * to expand the root.
  	 */
  	xfs_iroot_realloc(ip, 1, whichfork);
  	ifp->if_flags |= XFS_IFBROOT;
  
  	/*
  	 * Fill in the root.
  	 */
  	block = ifp->if_broot;
  	xfs_btree_init_block_int(mp, block, XFS_BUF_DADDR_NULL,
  				 XFS_BTNUM_BMAP, 1, 1, ip->i_ino,
  				 XFS_BTREE_LONG_PTRS);
  	/*
  	 * Need a cursor.  Can't allocate until bb_level is filled in.
  	 */
  	cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
  	cur->bc_private.b.flags = wasdel ? XFS_BTCUR_BPRV_WASDEL : 0;
  	/*
  	 * Convert to a btree with two levels, one record in root.
  	 */
  	XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_BTREE);
  	memset(&args, 0, sizeof(args));
  	args.tp = tp;
  	args.mp = mp;
  	xfs_rmap_ino_bmbt_owner(&args.oinfo, ip->i_ino, whichfork);
  	if (tp->t_firstblock == NULLFSBLOCK) {
  		args.type = XFS_ALLOCTYPE_START_BNO;
  		args.fsbno = XFS_INO_TO_FSB(mp, ip->i_ino);
  	} else if (tp->t_flags & XFS_TRANS_LOWMODE) {
  		args.type = XFS_ALLOCTYPE_START_BNO;
  		args.fsbno = tp->t_firstblock;
  	} else {
  		args.type = XFS_ALLOCTYPE_NEAR_BNO;
  		args.fsbno = tp->t_firstblock;
  	}
  	args.minlen = args.maxlen = args.prod = 1;
  	args.wasdel = wasdel;
  	*logflagsp = 0;
  	error = xfs_alloc_vextent(&args);
  	if (error)
  		goto out_root_realloc;
  
  	if (WARN_ON_ONCE(args.fsbno == NULLFSBLOCK)) {
  		error = -ENOSPC;
  		goto out_root_realloc;
  	}
  
  	/*
  	 * Allocation can't fail, the space was reserved.
  	 */
  	ASSERT(tp->t_firstblock == NULLFSBLOCK ||
  	       args.agno >= XFS_FSB_TO_AGNO(mp, tp->t_firstblock));
  	tp->t_firstblock = args.fsbno;
  	cur->bc_private.b.allocated++;
  	ip->i_d.di_nblocks++;
  	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, 1L);
  	abp = xfs_btree_get_bufl(mp, tp, args.fsbno, 0);
  	if (!abp) {
  		error = -EFSCORRUPTED;
  		goto out_unreserve_dquot;
  	}
  
  	/*
  	 * Fill in the child block.
  	 */
  	abp->b_ops = &xfs_bmbt_buf_ops;
  	ablock = XFS_BUF_TO_BLOCK(abp);
  	xfs_btree_init_block_int(mp, ablock, abp->b_bn,
  				XFS_BTNUM_BMAP, 0, 0, ip->i_ino,
  				XFS_BTREE_LONG_PTRS);
  
  	for_each_xfs_iext(ifp, &icur, &rec) {
  		if (isnullstartblock(rec.br_startblock))
  			continue;
  		arp = XFS_BMBT_REC_ADDR(mp, ablock, 1 + cnt);
  		xfs_bmbt_disk_set_all(arp, &rec);
  		cnt++;
  	}
  	ASSERT(cnt == XFS_IFORK_NEXTENTS(ip, whichfork));
  	xfs_btree_set_numrecs(ablock, cnt);
  
  	/*
  	 * Fill in the root key and pointer.
  	 */
  	kp = XFS_BMBT_KEY_ADDR(mp, block, 1);
  	arp = XFS_BMBT_REC_ADDR(mp, ablock, 1);
  	kp->br_startoff = cpu_to_be64(xfs_bmbt_disk_get_startoff(arp));
  	pp = XFS_BMBT_PTR_ADDR(mp, block, 1, xfs_bmbt_get_maxrecs(cur,
  						be16_to_cpu(block->bb_level)));
  	*pp = cpu_to_be64(args.fsbno);
  
  	/*
  	 * Do all this logging at the end so that
  	 * the root is at the right level.
  	 */
  	xfs_btree_log_block(cur, abp, XFS_BB_ALL_BITS);
  	xfs_btree_log_recs(cur, abp, 1, be16_to_cpu(ablock->bb_numrecs));
  	ASSERT(*curp == NULL);
  	*curp = cur;
  	*logflagsp = XFS_ILOG_CORE | xfs_ilog_fbroot(whichfork);
  	return 0;
  
  out_unreserve_dquot:
  	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L);
  out_root_realloc:
  	xfs_iroot_realloc(ip, -1, whichfork);
  	XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_EXTENTS);
  	ASSERT(ifp->if_broot == NULL);
  	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  
  	return error;
  }
  
  /*
   * Convert a local file to an extents file.
   * This code is out of bounds for data forks of regular files,
   * since the file data needs to get logged so things will stay consistent.
   * (The bmap-level manipulations are ok, though).
   */
  void
  xfs_bmap_local_to_extents_empty(
  	struct xfs_inode	*ip,
  	int			whichfork)
  {
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  
  	ASSERT(whichfork != XFS_COW_FORK);
  	ASSERT(XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL);
  	ASSERT(ifp->if_bytes == 0);
  	ASSERT(XFS_IFORK_NEXTENTS(ip, whichfork) == 0);
  
  	xfs_bmap_forkoff_reset(ip, whichfork);
  	ifp->if_flags &= ~XFS_IFINLINE;
  	ifp->if_flags |= XFS_IFEXTENTS;
  	ifp->if_u1.if_root = NULL;
  	ifp->if_height = 0;
  	XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_EXTENTS);
  }
  
  
  STATIC int				/* error */
  xfs_bmap_local_to_extents(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_inode_t	*ip,		/* incore inode pointer */
  	xfs_extlen_t	total,		/* total blocks needed by transaction */
  	int		*logflagsp,	/* inode logging flags */
  	int		whichfork,
  	void		(*init_fn)(struct xfs_trans *tp,
  				   struct xfs_buf *bp,
  				   struct xfs_inode *ip,
  				   struct xfs_ifork *ifp))
  {
  	int		error = 0;
  	int		flags;		/* logging flags returned */
  	struct xfs_ifork *ifp;		/* inode fork pointer */
  	xfs_alloc_arg_t	args;		/* allocation arguments */
  	xfs_buf_t	*bp;		/* buffer for extent block */
  	struct xfs_bmbt_irec rec;
  	struct xfs_iext_cursor icur;
  
  	/*
  	 * We don't want to deal with the case of keeping inode data inline yet.
  	 * So sending the data fork of a regular inode is invalid.
  	 */
  	ASSERT(!(S_ISREG(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK));
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	ASSERT(XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL);
  
  	if (!ifp->if_bytes) {
  		xfs_bmap_local_to_extents_empty(ip, whichfork);
  		flags = XFS_ILOG_CORE;
  		goto done;
  	}
  
  	flags = 0;
  	error = 0;
  	ASSERT((ifp->if_flags & (XFS_IFINLINE|XFS_IFEXTENTS)) == XFS_IFINLINE);
  	memset(&args, 0, sizeof(args));
  	args.tp = tp;
  	args.mp = ip->i_mount;
  	xfs_rmap_ino_owner(&args.oinfo, ip->i_ino, whichfork, 0);
  	/*
  	 * Allocate a block.  We know we need only one, since the
  	 * file currently fits in an inode.
  	 */
  	if (tp->t_firstblock == NULLFSBLOCK) {
  		args.fsbno = XFS_INO_TO_FSB(args.mp, ip->i_ino);
  		args.type = XFS_ALLOCTYPE_START_BNO;
  	} else {
  		args.fsbno = tp->t_firstblock;
  		args.type = XFS_ALLOCTYPE_NEAR_BNO;
  	}
  	args.total = total;
  	args.minlen = args.maxlen = args.prod = 1;
  	error = xfs_alloc_vextent(&args);
  	if (error)
  		goto done;
  
  	/* Can't fail, the space was reserved. */
  	ASSERT(args.fsbno != NULLFSBLOCK);
  	ASSERT(args.len == 1);
  	tp->t_firstblock = args.fsbno;
  	bp = xfs_btree_get_bufl(args.mp, tp, args.fsbno, 0);
  
  	/*
  	 * Initialize the block, copy the data and log the remote buffer.
  	 *
  	 * The callout is responsible for logging because the remote format
  	 * might differ from the local format and thus we don't know how much to
  	 * log here. Note that init_fn must also set the buffer log item type
  	 * correctly.
  	 */
  	init_fn(tp, bp, ip, ifp);
  
  	/* account for the change in fork size */
  	xfs_idata_realloc(ip, -ifp->if_bytes, whichfork);
  	xfs_bmap_local_to_extents_empty(ip, whichfork);
  	flags |= XFS_ILOG_CORE;
  
  	ifp->if_u1.if_root = NULL;
  	ifp->if_height = 0;
  
  	rec.br_startoff = 0;
  	rec.br_startblock = args.fsbno;
  	rec.br_blockcount = 1;
  	rec.br_state = XFS_EXT_NORM;
  	xfs_iext_first(ifp, &icur);
  	xfs_iext_insert(ip, &icur, &rec, 0);
  
  	XFS_IFORK_NEXT_SET(ip, whichfork, 1);
  	ip->i_d.di_nblocks = 1;
  	xfs_trans_mod_dquot_byino(tp, ip,
  		XFS_TRANS_DQ_BCOUNT, 1L);
  	flags |= xfs_ilog_fext(whichfork);
  
  done:
  	*logflagsp = flags;
  	return error;
  }
  
  /*
   * Called from xfs_bmap_add_attrfork to handle btree format files.
   */
  STATIC int					/* error */
  xfs_bmap_add_attrfork_btree(
  	xfs_trans_t		*tp,		/* transaction pointer */
  	xfs_inode_t		*ip,		/* incore inode pointer */
  	int			*flags)		/* inode logging flags */
  {
  	xfs_btree_cur_t		*cur;		/* btree cursor */
  	int			error;		/* error return value */
  	xfs_mount_t		*mp;		/* file system mount struct */
  	int			stat;		/* newroot status */
  
  	mp = ip->i_mount;
  	if (ip->i_df.if_broot_bytes <= XFS_IFORK_DSIZE(ip))
  		*flags |= XFS_ILOG_DBROOT;
  	else {
  		cur = xfs_bmbt_init_cursor(mp, tp, ip, XFS_DATA_FORK);
  		error = xfs_bmbt_lookup_first(cur, &stat);
  		if (error)
  			goto error0;
  		/* must be at least one entry */
  		XFS_WANT_CORRUPTED_GOTO(mp, stat == 1, error0);
  		if ((error = xfs_btree_new_iroot(cur, flags, &stat)))
  			goto error0;
  		if (stat == 0) {
  			xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  			return -ENOSPC;
  		}
  		cur->bc_private.b.allocated = 0;
  		xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
  	}
  	return 0;
  error0:
  	xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
  	return error;
  }
  
  /*
   * Called from xfs_bmap_add_attrfork to handle extents format files.
   */
  STATIC int					/* error */
  xfs_bmap_add_attrfork_extents(
  	struct xfs_trans	*tp,		/* transaction pointer */
  	struct xfs_inode	*ip,		/* incore inode pointer */
  	int			*flags)		/* inode logging flags */
  {
  	xfs_btree_cur_t		*cur;		/* bmap btree cursor */
  	int			error;		/* error return value */
  
  	if (ip->i_d.di_nextents * sizeof(xfs_bmbt_rec_t) <= XFS_IFORK_DSIZE(ip))
  		return 0;
  	cur = NULL;
  	error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0, flags,
  					  XFS_DATA_FORK);
  	if (cur) {
  		cur->bc_private.b.allocated = 0;
  		xfs_btree_del_cursor(cur, error);
  	}
  	return error;
  }
  
  /*
   * Called from xfs_bmap_add_attrfork to handle local format files. Each
   * different data fork content type needs a different callout to do the
   * conversion. Some are basic and only require special block initialisation
   * callouts for the data formating, others (directories) are so specialised they
   * handle everything themselves.
   *
   * XXX (dgc): investigate whether directory conversion can use the generic
   * formatting callout. It should be possible - it's just a very complex
   * formatter.
   */
  STATIC int					/* error */
  xfs_bmap_add_attrfork_local(
  	struct xfs_trans	*tp,		/* transaction pointer */
  	struct xfs_inode	*ip,		/* incore inode pointer */
  	int			*flags)		/* inode logging flags */
  {
  	struct xfs_da_args	dargs;		/* args for dir/attr code */
  
  	if (ip->i_df.if_bytes <= XFS_IFORK_DSIZE(ip))
  		return 0;
  
  	if (S_ISDIR(VFS_I(ip)->i_mode)) {
  		memset(&dargs, 0, sizeof(dargs));
  		dargs.geo = ip->i_mount->m_dir_geo;
  		dargs.dp = ip;
  		dargs.total = dargs.geo->fsbcount;
  		dargs.whichfork = XFS_DATA_FORK;
  		dargs.trans = tp;
  		return xfs_dir2_sf_to_block(&dargs);
  	}
  
  	if (S_ISLNK(VFS_I(ip)->i_mode))
  		return xfs_bmap_local_to_extents(tp, ip, 1, flags,
  						 XFS_DATA_FORK,
  						 xfs_symlink_local_to_remote);
  
  	/* should only be called for types that support local format data */
  	ASSERT(0);
  	return -EFSCORRUPTED;
  }
  
  /* Set an inode attr fork off based on the format */
  int
  xfs_bmap_set_attrforkoff(
  	struct xfs_inode	*ip,
  	int			size,
  	int			*version)
  {
  	switch (ip->i_d.di_format) {
  	case XFS_DINODE_FMT_DEV:
  		ip->i_d.di_forkoff = roundup(sizeof(xfs_dev_t), 8) >> 3;
  		break;
  	case XFS_DINODE_FMT_LOCAL:
  	case XFS_DINODE_FMT_EXTENTS:
  	case XFS_DINODE_FMT_BTREE:
  		ip->i_d.di_forkoff = xfs_attr_shortform_bytesfit(ip, size);
  		if (!ip->i_d.di_forkoff)
  			ip->i_d.di_forkoff = xfs_default_attroffset(ip) >> 3;
  		else if ((ip->i_mount->m_flags & XFS_MOUNT_ATTR2) && version)
  			*version = 2;
  		break;
  	default:
  		ASSERT(0);
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  /*
   * Convert inode from non-attributed to attributed.
   * Must not be in a transaction, ip must not be locked.
   */
  int						/* error code */
  xfs_bmap_add_attrfork(
  	xfs_inode_t		*ip,		/* incore inode pointer */
  	int			size,		/* space new attribute needs */
  	int			rsvd)		/* xact may use reserved blks */
  {
  	xfs_mount_t		*mp;		/* mount structure */
  	xfs_trans_t		*tp;		/* transaction pointer */
  	int			blks;		/* space reservation */
  	int			version = 1;	/* superblock attr version */
  	int			logflags;	/* logging flags */
  	int			error;		/* error return value */
  
  	ASSERT(XFS_IFORK_Q(ip) == 0);
  
  	mp = ip->i_mount;
  	ASSERT(!XFS_NOT_DQATTACHED(mp, ip));
  
  	blks = XFS_ADDAFORK_SPACE_RES(mp);
  
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_addafork, blks, 0,
  			rsvd ? XFS_TRANS_RESERVE : 0, &tp);
  	if (error)
  		return error;
  
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	error = xfs_trans_reserve_quota_nblks(tp, ip, blks, 0, rsvd ?
  			XFS_QMOPT_RES_REGBLKS | XFS_QMOPT_FORCE_RES :
  			XFS_QMOPT_RES_REGBLKS);
  	if (error)
  		goto trans_cancel;
  	if (XFS_IFORK_Q(ip))
  		goto trans_cancel;
  	if (ip->i_d.di_anextents != 0) {
  		error = -EFSCORRUPTED;
  		goto trans_cancel;
  	}
  	if (ip->i_d.di_aformat != XFS_DINODE_FMT_EXTENTS) {
  		/*
  		 * For inodes coming from pre-6.2 filesystems.
  		 */
  		ASSERT(ip->i_d.di_aformat == 0);
  		ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
  	}
  
  	xfs_trans_ijoin(tp, ip, 0);
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  	error = xfs_bmap_set_attrforkoff(ip, size, &version);
  	if (error)
  		goto trans_cancel;
  	ASSERT(ip->i_afp == NULL);
  	ip->i_afp = kmem_zone_zalloc(xfs_ifork_zone, KM_SLEEP);
  	ip->i_afp->if_flags = XFS_IFEXTENTS;
  	logflags = 0;
  	switch (ip->i_d.di_format) {
  	case XFS_DINODE_FMT_LOCAL:
  		error = xfs_bmap_add_attrfork_local(tp, ip, &logflags);
  		break;
  	case XFS_DINODE_FMT_EXTENTS:
  		error = xfs_bmap_add_attrfork_extents(tp, ip, &logflags);
  		break;
  	case XFS_DINODE_FMT_BTREE:
  		error = xfs_bmap_add_attrfork_btree(tp, ip, &logflags);
  		break;
  	default:
  		error = 0;
  		break;
  	}
  	if (logflags)
  		xfs_trans_log_inode(tp, ip, logflags);
  	if (error)
  		goto trans_cancel;
  	if (!xfs_sb_version_hasattr(&mp->m_sb) ||
  	   (!xfs_sb_version_hasattr2(&mp->m_sb) && version == 2)) {
  		bool log_sb = false;
  
  		spin_lock(&mp->m_sb_lock);
  		if (!xfs_sb_version_hasattr(&mp->m_sb)) {
  			xfs_sb_version_addattr(&mp->m_sb);
  			log_sb = true;
  		}
  		if (!xfs_sb_version_hasattr2(&mp->m_sb) && version == 2) {
  			xfs_sb_version_addattr2(&mp->m_sb);
  			log_sb = true;
  		}
  		spin_unlock(&mp->m_sb_lock);
  		if (log_sb)
  			xfs_log_sb(tp);
  	}
  
  	error = xfs_trans_commit(tp);
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return error;
  
  trans_cancel:
  	xfs_trans_cancel(tp);
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return error;
  }
  
  /*
   * Internal and external extent tree search functions.
   */
  
  /*
   * Read in extents from a btree-format inode.
   */
  int
  xfs_iread_extents(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	int			whichfork)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	int			state = xfs_bmap_fork_to_state(whichfork);
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	xfs_extnum_t		nextents = XFS_IFORK_NEXTENTS(ip, whichfork);
  	struct xfs_btree_block	*block = ifp->if_broot;
  	struct xfs_iext_cursor	icur;
  	struct xfs_bmbt_irec	new;
  	xfs_fsblock_t		bno;
  	struct xfs_buf		*bp;
  	xfs_extnum_t		i, j;
  	int			level;
  	__be64			*pp;
  	int			error;
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  
  	if (unlikely(XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE)) {
  		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, mp);
  		return -EFSCORRUPTED;
  	}
  
  	/*
  	 * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out.
  	 */
  	level = be16_to_cpu(block->bb_level);
  	if (unlikely(level == 0)) {
  		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, mp);
  		return -EFSCORRUPTED;
  	}
  	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes);
  	bno = be64_to_cpu(*pp);
  
  	/*
  	 * Go down the tree until leaf level is reached, following the first
  	 * pointer (leftmost) at each level.
  	 */
  	while (level-- > 0) {
  		error = xfs_btree_read_bufl(mp, tp, bno, 0, &bp,
  				XFS_BMAP_BTREE_REF, &xfs_bmbt_buf_ops);
  		if (error)
  			goto out;
  		block = XFS_BUF_TO_BLOCK(bp);
  		if (level == 0)
  			break;
  		pp = XFS_BMBT_PTR_ADDR(mp, block, 1, mp->m_bmap_dmxr[1]);
  		bno = be64_to_cpu(*pp);
  		XFS_WANT_CORRUPTED_GOTO(mp,
  			xfs_verify_fsbno(mp, bno), out_brelse);
  		xfs_trans_brelse(tp, bp);
  	}
  
  	/*
  	 * Here with bp and block set to the leftmost leaf node in the tree.
  	 */
  	i = 0;
  	xfs_iext_first(ifp, &icur);
  
  	/*
  	 * Loop over all leaf nodes.  Copy information to the extent records.
  	 */
  	for (;;) {
  		xfs_bmbt_rec_t	*frp;
  		xfs_fsblock_t	nextbno;
  		xfs_extnum_t	num_recs;
  
  		num_recs = xfs_btree_get_numrecs(block);
  		if (unlikely(i + num_recs > nextents)) {
  			xfs_warn(ip->i_mount,
  				"corrupt dinode %Lu, (btree extents).",
  				(unsigned long long) ip->i_ino);
  			xfs_inode_verifier_error(ip, -EFSCORRUPTED,
  					__func__, block, sizeof(*block),
  					__this_address);
  			error = -EFSCORRUPTED;
  			goto out_brelse;
  		}
  		/*
  		 * Read-ahead the next leaf block, if any.
  		 */
  		nextbno = be64_to_cpu(block->bb_u.l.bb_rightsib);
  		if (nextbno != NULLFSBLOCK)
  			xfs_btree_reada_bufl(mp, nextbno, 1,
  					     &xfs_bmbt_buf_ops);
  		/*
  		 * Copy records into the extent records.
  		 */
  		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
  		for (j = 0; j < num_recs; j++, frp++, i++) {
  			xfs_failaddr_t	fa;
  
  			xfs_bmbt_disk_get_all(frp, &new);
  			fa = xfs_bmap_validate_extent(ip, whichfork, &new);
  			if (fa) {
  				error = -EFSCORRUPTED;
  				xfs_inode_verifier_error(ip, error,
  						"xfs_iread_extents(2)",
  						frp, sizeof(*frp), fa);
  				goto out_brelse;
  			}
  			xfs_iext_insert(ip, &icur, &new, state);
  			trace_xfs_read_extent(ip, &icur, state, _THIS_IP_);
  			xfs_iext_next(ifp, &icur);
  		}
  		xfs_trans_brelse(tp, bp);
  		bno = nextbno;
  		/*
  		 * If we've reached the end, stop.
  		 */
  		if (bno == NULLFSBLOCK)
  			break;
  		error = xfs_btree_read_bufl(mp, tp, bno, 0, &bp,
  				XFS_BMAP_BTREE_REF, &xfs_bmbt_buf_ops);
  		if (error)
  			goto out;
  		block = XFS_BUF_TO_BLOCK(bp);
  	}
  
  	if (i != XFS_IFORK_NEXTENTS(ip, whichfork)) {
  		error = -EFSCORRUPTED;
  		goto out;
  	}
  	ASSERT(i == xfs_iext_count(ifp));
  
  	ifp->if_flags |= XFS_IFEXTENTS;
  	return 0;
  
  out_brelse:
  	xfs_trans_brelse(tp, bp);
  out:
  	xfs_iext_destroy(ifp);
  	return error;
  }
  
  /*
   * Returns the relative block number of the first unused block(s) in the given
   * fork with at least "len" logically contiguous blocks free.  This is the
   * lowest-address hole if the fork has holes, else the first block past the end
   * of fork.  Return 0 if the fork is currently local (in-inode).
   */
  int						/* error */
  xfs_bmap_first_unused(
  	struct xfs_trans	*tp,		/* transaction pointer */
  	struct xfs_inode	*ip,		/* incore inode */
  	xfs_extlen_t		len,		/* size of hole to find */
  	xfs_fileoff_t		*first_unused,	/* unused block */
  	int			whichfork)	/* data or attr fork */
  {
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_bmbt_irec	got;
  	struct xfs_iext_cursor	icur;
  	xfs_fileoff_t		lastaddr = 0;
  	xfs_fileoff_t		lowest, max;
  	int			error;
  
  	ASSERT(XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_BTREE ||
  	       XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_EXTENTS ||
  	       XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL);
  
  	if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL) {
  		*first_unused = 0;
  		return 0;
  	}
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(tp, ip, whichfork);
  		if (error)
  			return error;
  	}
  
  	lowest = max = *first_unused;
  	for_each_xfs_iext(ifp, &icur, &got) {
  		/*
  		 * See if the hole before this extent will work.
  		 */
  		if (got.br_startoff >= lowest + len &&
  		    got.br_startoff - max >= len)
  			break;
  		lastaddr = got.br_startoff + got.br_blockcount;
  		max = XFS_FILEOFF_MAX(lastaddr, lowest);
  	}
  
  	*first_unused = max;
  	return 0;
  }
  
  /*
   * Returns the file-relative block number of the last block - 1 before
   * last_block (input value) in the file.
   * This is not based on i_size, it is based on the extent records.
   * Returns 0 for local files, as they do not have extent records.
   */
  int						/* error */
  xfs_bmap_last_before(
  	struct xfs_trans	*tp,		/* transaction pointer */
  	struct xfs_inode	*ip,		/* incore inode */
  	xfs_fileoff_t		*last_block,	/* last block */
  	int			whichfork)	/* data or attr fork */
  {
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_bmbt_irec	got;
  	struct xfs_iext_cursor	icur;
  	int			error;
  
  	switch (XFS_IFORK_FORMAT(ip, whichfork)) {
  	case XFS_DINODE_FMT_LOCAL:
  		*last_block = 0;
  		return 0;
  	case XFS_DINODE_FMT_BTREE:
  	case XFS_DINODE_FMT_EXTENTS:
  		break;
  	default:
  		return -EIO;
  	}
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(tp, ip, whichfork);
  		if (error)
  			return error;
  	}
  
  	if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &icur, &got))
  		*last_block = 0;
  	return 0;
  }
  
  int
  xfs_bmap_last_extent(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	int			whichfork,
  	struct xfs_bmbt_irec	*rec,
  	int			*is_empty)
  {
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_iext_cursor	icur;
  	int			error;
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(tp, ip, whichfork);
  		if (error)
  			return error;
  	}
  
  	xfs_iext_last(ifp, &icur);
  	if (!xfs_iext_get_extent(ifp, &icur, rec))
  		*is_empty = 1;
  	else
  		*is_empty = 0;
  	return 0;
  }
  
  /*
   * Check the last inode extent to determine whether this allocation will result
   * in blocks being allocated at the end of the file. When we allocate new data
   * blocks at the end of the file which do not start at the previous data block,
   * we will try to align the new blocks at stripe unit boundaries.
   *
   * Returns 1 in bma->aeof if the file (fork) is empty as any new write will be
   * at, or past the EOF.
   */
  STATIC int
  xfs_bmap_isaeof(
  	struct xfs_bmalloca	*bma,
  	int			whichfork)
  {
  	struct xfs_bmbt_irec	rec;
  	int			is_empty;
  	int			error;
  
  	bma->aeof = false;
  	error = xfs_bmap_last_extent(NULL, bma->ip, whichfork, &rec,
  				     &is_empty);
  	if (error)
  		return error;
  
  	if (is_empty) {
  		bma->aeof = true;
  		return 0;
  	}
  
  	/*
  	 * Check if we are allocation or past the last extent, or at least into
  	 * the last delayed allocated extent.
  	 */
  	bma->aeof = bma->offset >= rec.br_startoff + rec.br_blockcount ||
  		(bma->offset >= rec.br_startoff &&
  		 isnullstartblock(rec.br_startblock));
  	return 0;
  }
  
  /*
   * Returns the file-relative block number of the first block past eof in
   * the file.  This is not based on i_size, it is based on the extent records.
   * Returns 0 for local files, as they do not have extent records.
   */
  int
  xfs_bmap_last_offset(
  	struct xfs_inode	*ip,
  	xfs_fileoff_t		*last_block,
  	int			whichfork)
  {
  	struct xfs_bmbt_irec	rec;
  	int			is_empty;
  	int			error;
  
  	*last_block = 0;
  
  	if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL)
  		return 0;
  
  	if (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE &&
  	    XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS)
  	       return -EIO;
  
  	error = xfs_bmap_last_extent(NULL, ip, whichfork, &rec, &is_empty);
  	if (error || is_empty)
  		return error;
  
  	*last_block = rec.br_startoff + rec.br_blockcount;
  	return 0;
  }
  
  /*
   * Returns whether the selected fork of the inode has exactly one
   * block or not.  For the data fork we check this matches di_size,
   * implying the file's range is 0..bsize-1.
   */
  int					/* 1=>1 block, 0=>otherwise */
  xfs_bmap_one_block(
  	xfs_inode_t	*ip,		/* incore inode */
  	int		whichfork)	/* data or attr fork */
  {
  	struct xfs_ifork *ifp;		/* inode fork pointer */
  	int		rval;		/* return value */
  	xfs_bmbt_irec_t	s;		/* internal version of extent */
  	struct xfs_iext_cursor icur;
  
  #ifndef DEBUG
  	if (whichfork == XFS_DATA_FORK)
  		return XFS_ISIZE(ip) == ip->i_mount->m_sb.sb_blocksize;
  #endif	/* !DEBUG */
  	if (XFS_IFORK_NEXTENTS(ip, whichfork) != 1)
  		return 0;
  	if (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS)
  		return 0;
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	ASSERT(ifp->if_flags & XFS_IFEXTENTS);
  	xfs_iext_first(ifp, &icur);
  	xfs_iext_get_extent(ifp, &icur, &s);
  	rval = s.br_startoff == 0 && s.br_blockcount == 1;
  	if (rval && whichfork == XFS_DATA_FORK)
  		ASSERT(XFS_ISIZE(ip) == ip->i_mount->m_sb.sb_blocksize);
  	return rval;
  }
  
  /*
   * Extent tree manipulation functions used during allocation.
   */
  
  /*
   * Convert a delayed allocation to a real allocation.
   */
  STATIC int				/* error */
  xfs_bmap_add_extent_delay_real(
  	struct xfs_bmalloca	*bma,
  	int			whichfork)
  {
  	struct xfs_bmbt_irec	*new = &bma->got;
  	int			error;	/* error return value */
  	int			i;	/* temp state */
  	struct xfs_ifork	*ifp;	/* inode fork pointer */
  	xfs_fileoff_t		new_endoff;	/* end offset of new entry */
  	xfs_bmbt_irec_t		r[3];	/* neighbor extent entries */
  					/* left is 0, right is 1, prev is 2 */
  	int			rval=0;	/* return value (logging flags) */
  	int			state = xfs_bmap_fork_to_state(whichfork);
  	xfs_filblks_t		da_new; /* new count del alloc blocks used */
  	xfs_filblks_t		da_old; /* old count del alloc blocks used */
  	xfs_filblks_t		temp=0;	/* value for da_new calculations */
  	int			tmp_rval;	/* partial logging flags */
  	struct xfs_mount	*mp;
  	xfs_extnum_t		*nextents;
  	struct xfs_bmbt_irec	old;
  
  	mp = bma->ip->i_mount;
  	ifp = XFS_IFORK_PTR(bma->ip, whichfork);
  	ASSERT(whichfork != XFS_ATTR_FORK);
  	nextents = (whichfork == XFS_COW_FORK ? &bma->ip->i_cnextents :
  						&bma->ip->i_d.di_nextents);
  
  	ASSERT(!isnullstartblock(new->br_startblock));
  	ASSERT(!bma->cur ||
  	       (bma->cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL));
  
  	XFS_STATS_INC(mp, xs_add_exlist);
  
  #define	LEFT		r[0]
  #define	RIGHT		r[1]
  #define	PREV		r[2]
  
  	/*
  	 * Set up a bunch of variables to make the tests simpler.
  	 */
  	xfs_iext_get_extent(ifp, &bma->icur, &PREV);
  	new_endoff = new->br_startoff + new->br_blockcount;
  	ASSERT(isnullstartblock(PREV.br_startblock));
  	ASSERT(PREV.br_startoff <= new->br_startoff);
  	ASSERT(PREV.br_startoff + PREV.br_blockcount >= new_endoff);
  
  	da_old = startblockval(PREV.br_startblock);
  	da_new = 0;
  
  	/*
  	 * Set flags determining what part of the previous delayed allocation
  	 * extent is being replaced by a real allocation.
  	 */
  	if (PREV.br_startoff == new->br_startoff)
  		state |= BMAP_LEFT_FILLING;
  	if (PREV.br_startoff + PREV.br_blockcount == new_endoff)
  		state |= BMAP_RIGHT_FILLING;
  
  	/*
  	 * Check and set flags if this segment has a left neighbor.
  	 * Don't set contiguous if the combined extent would be too large.
  	 */
  	if (xfs_iext_peek_prev_extent(ifp, &bma->icur, &LEFT)) {
  		state |= BMAP_LEFT_VALID;
  		if (isnullstartblock(LEFT.br_startblock))
  			state |= BMAP_LEFT_DELAY;
  	}
  
  	if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
  	    LEFT.br_startoff + LEFT.br_blockcount == new->br_startoff &&
  	    LEFT.br_startblock + LEFT.br_blockcount == new->br_startblock &&
  	    LEFT.br_state == new->br_state &&
  	    LEFT.br_blockcount + new->br_blockcount <= MAXEXTLEN)
  		state |= BMAP_LEFT_CONTIG;
  
  	/*
  	 * Check and set flags if this segment has a right neighbor.
  	 * Don't set contiguous if the combined extent would be too large.
  	 * Also check for all-three-contiguous being too large.
  	 */
  	if (xfs_iext_peek_next_extent(ifp, &bma->icur, &RIGHT)) {
  		state |= BMAP_RIGHT_VALID;
  		if (isnullstartblock(RIGHT.br_startblock))
  			state |= BMAP_RIGHT_DELAY;
  	}
  
  	if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
  	    new_endoff == RIGHT.br_startoff &&
  	    new->br_startblock + new->br_blockcount == RIGHT.br_startblock &&
  	    new->br_state == RIGHT.br_state &&
  	    new->br_blockcount + RIGHT.br_blockcount <= MAXEXTLEN &&
  	    ((state & (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
  		       BMAP_RIGHT_FILLING)) !=
  		      (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
  		       BMAP_RIGHT_FILLING) ||
  	     LEFT.br_blockcount + new->br_blockcount + RIGHT.br_blockcount
  			<= MAXEXTLEN))
  		state |= BMAP_RIGHT_CONTIG;
  
  	error = 0;
  	/*
  	 * Switch out based on the FILLING and CONTIG state bits.
  	 */
  	switch (state & (BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
  			 BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG)) {
  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
  	     BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
  		/*
  		 * Filling in all of a previously delayed allocation extent.
  		 * The left and right neighbors are both contiguous with new.
  		 */
  		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
  
  		xfs_iext_remove(bma->ip, &bma->icur, state);
  		xfs_iext_remove(bma->ip, &bma->icur, state);
  		xfs_iext_prev(ifp, &bma->icur);
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
  		(*nextents)--;
  
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(bma->cur, &RIGHT, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_btree_delete(bma->cur, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_btree_decrement(bma->cur, 0, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(bma->cur, &LEFT);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
  		/*
  		 * Filling in all of a previously delayed allocation extent.
  		 * The left neighbor is contiguous, the right is not.
  		 */
  		old = LEFT;
  		LEFT.br_blockcount += PREV.br_blockcount;
  
  		xfs_iext_remove(bma->ip, &bma->icur, state);
  		xfs_iext_prev(ifp, &bma->icur);
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
  
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_DEXT;
  		else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(bma->cur, &LEFT);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
  		/*
  		 * Filling in all of a previously delayed allocation extent.
  		 * The right neighbor is contiguous, the left is not. Take care
  		 * with delay -> unwritten extent allocation here because the
  		 * delalloc record we are overwriting is always written.
  		 */
  		PREV.br_startblock = new->br_startblock;
  		PREV.br_blockcount += RIGHT.br_blockcount;
  		PREV.br_state = new->br_state;
  
  		xfs_iext_next(ifp, &bma->icur);
  		xfs_iext_remove(bma->ip, &bma->icur, state);
  		xfs_iext_prev(ifp, &bma->icur);
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
  
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_DEXT;
  		else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(bma->cur, &RIGHT, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(bma->cur, &PREV);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
  		/*
  		 * Filling in all of a previously delayed allocation extent.
  		 * Neither the left nor right neighbors are contiguous with
  		 * the new one.
  		 */
  		PREV.br_startblock = new->br_startblock;
  		PREV.br_state = new->br_state;
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
  
  		(*nextents)++;
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
  			error = xfs_btree_insert(bma->cur, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG:
  		/*
  		 * Filling in the first part of a previous delayed allocation.
  		 * The left neighbor is contiguous.
  		 */
  		old = LEFT;
  		temp = PREV.br_blockcount - new->br_blockcount;
  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
  				startblockval(PREV.br_startblock));
  
  		LEFT.br_blockcount += new->br_blockcount;
  
  		PREV.br_blockcount = temp;
  		PREV.br_startoff += new->br_blockcount;
  		PREV.br_startblock = nullstartblock(da_new);
  
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
  		xfs_iext_prev(ifp, &bma->icur);
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &LEFT);
  
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_DEXT;
  		else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(bma->cur, &LEFT);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING:
  		/*
  		 * Filling in the first part of a previous delayed allocation.
  		 * The left neighbor is not contiguous.
  		 */
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
  		(*nextents)++;
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
  			error = xfs_btree_insert(bma->cur, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		}
  
  		if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
  			error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
  					&bma->cur, 1, &tmp_rval, whichfork);
  			rval |= tmp_rval;
  			if (error)
  				goto done;
  		}
  
  		temp = PREV.br_blockcount - new->br_blockcount;
  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
  			startblockval(PREV.br_startblock) -
  			(bma->cur ? bma->cur->bc_private.b.allocated : 0));
  
  		PREV.br_startoff = new_endoff;
  		PREV.br_blockcount = temp;
  		PREV.br_startblock = nullstartblock(da_new);
  		xfs_iext_next(ifp, &bma->icur);
  		xfs_iext_insert(bma->ip, &bma->icur, &PREV, state);
  		xfs_iext_prev(ifp, &bma->icur);
  		break;
  
  	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
  		/*
  		 * Filling in the last part of a previous delayed allocation.
  		 * The right neighbor is contiguous with the new allocation.
  		 */
  		old = RIGHT;
  		RIGHT.br_startoff = new->br_startoff;
  		RIGHT.br_startblock = new->br_startblock;
  		RIGHT.br_blockcount += new->br_blockcount;
  
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_DEXT;
  		else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(bma->cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(bma->cur, &RIGHT);
  			if (error)
  				goto done;
  		}
  
  		temp = PREV.br_blockcount - new->br_blockcount;
  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
  			startblockval(PREV.br_startblock));
  
  		PREV.br_blockcount = temp;
  		PREV.br_startblock = nullstartblock(da_new);
  
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
  		xfs_iext_next(ifp, &bma->icur);
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &RIGHT);
  		break;
  
  	case BMAP_RIGHT_FILLING:
  		/*
  		 * Filling in the last part of a previous delayed allocation.
  		 * The right neighbor is not contiguous.
  		 */
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, new);
  		(*nextents)++;
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
  			error = xfs_btree_insert(bma->cur, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		}
  
  		if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
  			error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
  				&bma->cur, 1, &tmp_rval, whichfork);
  			rval |= tmp_rval;
  			if (error)
  				goto done;
  		}
  
  		temp = PREV.br_blockcount - new->br_blockcount;
  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(bma->ip, temp),
  			startblockval(PREV.br_startblock) -
  			(bma->cur ? bma->cur->bc_private.b.allocated : 0));
  
  		PREV.br_startblock = nullstartblock(da_new);
  		PREV.br_blockcount = temp;
  		xfs_iext_insert(bma->ip, &bma->icur, &PREV, state);
  		xfs_iext_next(ifp, &bma->icur);
  		break;
  
  	case 0:
  		/*
  		 * Filling in the middle part of a previous delayed allocation.
  		 * Contiguity is impossible here.
  		 * This case is avoided almost all the time.
  		 *
  		 * We start with a delayed allocation:
  		 *
  		 * +ddddddddddddddddddddddddddddddddddddddddddddddddddddddd+
  		 *  PREV @ idx
  		 *
  	         * and we are allocating:
  		 *                     +rrrrrrrrrrrrrrrrr+
  		 *			      new
  		 *
  		 * and we set it up for insertion as:
  		 * +ddddddddddddddddddd+rrrrrrrrrrrrrrrrr+ddddddddddddddddd+
  		 *                            new
  		 *  PREV @ idx          LEFT              RIGHT
  		 *                      inserted at idx + 1
  		 */
  		old = PREV;
  
  		/* LEFT is the new middle */
  		LEFT = *new;
  
  		/* RIGHT is the new right */
  		RIGHT.br_state = PREV.br_state;
  		RIGHT.br_startoff = new_endoff;
  		RIGHT.br_blockcount =
  			PREV.br_startoff + PREV.br_blockcount - new_endoff;
  		RIGHT.br_startblock =
  			nullstartblock(xfs_bmap_worst_indlen(bma->ip,
  					RIGHT.br_blockcount));
  
  		/* truncate PREV */
  		PREV.br_blockcount = new->br_startoff - PREV.br_startoff;
  		PREV.br_startblock =
  			nullstartblock(xfs_bmap_worst_indlen(bma->ip,
  					PREV.br_blockcount));
  		xfs_iext_update_extent(bma->ip, state, &bma->icur, &PREV);
  
  		xfs_iext_next(ifp, &bma->icur);
  		xfs_iext_insert(bma->ip, &bma->icur, &RIGHT, state);
  		xfs_iext_insert(bma->ip, &bma->icur, &LEFT, state);
  		(*nextents)++;
  
  		if (bma->cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(bma->cur, new, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
  			error = xfs_btree_insert(bma->cur, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		}
  
  		if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
  			error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
  					&bma->cur, 1, &tmp_rval, whichfork);
  			rval |= tmp_rval;
  			if (error)
  				goto done;
  		}
  
  		da_new = startblockval(PREV.br_startblock) +
  			 startblockval(RIGHT.br_startblock);
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
  	case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_CONTIG:
  	case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
  	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
  	case BMAP_LEFT_CONTIG:
  	case BMAP_RIGHT_CONTIG:
  		/*
  		 * These cases are all impossible.
  		 */
  		ASSERT(0);
  	}
  
  	/* add reverse mapping unless caller opted out */
  	if (!(bma->flags & XFS_BMAPI_NORMAP)) {
  		error = xfs_rmap_map_extent(bma->tp, bma->ip, whichfork, new);
  		if (error)
  			goto done;
  	}
  
  	/* convert to a btree if necessary */
  	if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
  		int	tmp_logflags;	/* partial log flag return val */
  
  		ASSERT(bma->cur == NULL);
  		error = xfs_bmap_extents_to_btree(bma->tp, bma->ip,
  				&bma->cur, da_old > 0, &tmp_logflags,
  				whichfork);
  		bma->logflags |= tmp_logflags;
  		if (error)
  			goto done;
  	}
  
  	if (da_new != da_old)
  		xfs_mod_delalloc(mp, (int64_t)da_new - da_old);
  
  	if (bma->cur) {
  		da_new += bma->cur->bc_private.b.allocated;
  		bma->cur->bc_private.b.allocated = 0;
  	}
  
  	/* adjust for changes in reserved delayed indirect blocks */
  	if (da_new != da_old) {
  		ASSERT(state == 0 || da_new < da_old);
  		error = xfs_mod_fdblocks(mp, (int64_t)(da_old - da_new),
  				false);
  	}
  
  	xfs_bmap_check_leaf_extents(bma->cur, bma->ip, whichfork);
  done:
  	if (whichfork != XFS_COW_FORK)
  		bma->logflags |= rval;
  	return error;
  #undef	LEFT
  #undef	RIGHT
  #undef	PREV
  }
  
  /*
   * Convert an unwritten allocation to a real allocation or vice versa.
   */
  int					/* error */
  xfs_bmap_add_extent_unwritten_real(
  	struct xfs_trans	*tp,
  	xfs_inode_t		*ip,	/* incore inode pointer */
  	int			whichfork,
  	struct xfs_iext_cursor	*icur,
  	xfs_btree_cur_t		**curp,	/* if *curp is null, not a btree */
  	xfs_bmbt_irec_t		*new,	/* new data to add to file extents */
  	int			*logflagsp) /* inode logging flags */
  {
  	xfs_btree_cur_t		*cur;	/* btree cursor */
  	int			error;	/* error return value */
  	int			i;	/* temp state */
  	struct xfs_ifork	*ifp;	/* inode fork pointer */
  	xfs_fileoff_t		new_endoff;	/* end offset of new entry */
  	xfs_bmbt_irec_t		r[3];	/* neighbor extent entries */
  					/* left is 0, right is 1, prev is 2 */
  	int			rval=0;	/* return value (logging flags) */
  	int			state = xfs_bmap_fork_to_state(whichfork);
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_bmbt_irec	old;
  
  	*logflagsp = 0;
  
  	cur = *curp;
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  
  	ASSERT(!isnullstartblock(new->br_startblock));
  
  	XFS_STATS_INC(mp, xs_add_exlist);
  
  #define	LEFT		r[0]
  #define	RIGHT		r[1]
  #define	PREV		r[2]
  
  	/*
  	 * Set up a bunch of variables to make the tests simpler.
  	 */
  	error = 0;
  	xfs_iext_get_extent(ifp, icur, &PREV);
  	ASSERT(new->br_state != PREV.br_state);
  	new_endoff = new->br_startoff + new->br_blockcount;
  	ASSERT(PREV.br_startoff <= new->br_startoff);
  	ASSERT(PREV.br_startoff + PREV.br_blockcount >= new_endoff);
  
  	/*
  	 * Set flags determining what part of the previous oldext allocation
  	 * extent is being replaced by a newext allocation.
  	 */
  	if (PREV.br_startoff == new->br_startoff)
  		state |= BMAP_LEFT_FILLING;
  	if (PREV.br_startoff + PREV.br_blockcount == new_endoff)
  		state |= BMAP_RIGHT_FILLING;
  
  	/*
  	 * Check and set flags if this segment has a left neighbor.
  	 * Don't set contiguous if the combined extent would be too large.
  	 */
  	if (xfs_iext_peek_prev_extent(ifp, icur, &LEFT)) {
  		state |= BMAP_LEFT_VALID;
  		if (isnullstartblock(LEFT.br_startblock))
  			state |= BMAP_LEFT_DELAY;
  	}
  
  	if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
  	    LEFT.br_startoff + LEFT.br_blockcount == new->br_startoff &&
  	    LEFT.br_startblock + LEFT.br_blockcount == new->br_startblock &&
  	    LEFT.br_state == new->br_state &&
  	    LEFT.br_blockcount + new->br_blockcount <= MAXEXTLEN)
  		state |= BMAP_LEFT_CONTIG;
  
  	/*
  	 * Check and set flags if this segment has a right neighbor.
  	 * Don't set contiguous if the combined extent would be too large.
  	 * Also check for all-three-contiguous being too large.
  	 */
  	if (xfs_iext_peek_next_extent(ifp, icur, &RIGHT)) {
  		state |= BMAP_RIGHT_VALID;
  		if (isnullstartblock(RIGHT.br_startblock))
  			state |= BMAP_RIGHT_DELAY;
  	}
  
  	if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
  	    new_endoff == RIGHT.br_startoff &&
  	    new->br_startblock + new->br_blockcount == RIGHT.br_startblock &&
  	    new->br_state == RIGHT.br_state &&
  	    new->br_blockcount + RIGHT.br_blockcount <= MAXEXTLEN &&
  	    ((state & (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
  		       BMAP_RIGHT_FILLING)) !=
  		      (BMAP_LEFT_CONTIG | BMAP_LEFT_FILLING |
  		       BMAP_RIGHT_FILLING) ||
  	     LEFT.br_blockcount + new->br_blockcount + RIGHT.br_blockcount
  			<= MAXEXTLEN))
  		state |= BMAP_RIGHT_CONTIG;
  
  	/*
  	 * Switch out based on the FILLING and CONTIG state bits.
  	 */
  	switch (state & (BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
  			 BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG)) {
  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG |
  	     BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
  		/*
  		 * Setting all of a previous oldext extent to newext.
  		 * The left and right neighbors are both contiguous with new.
  		 */
  		LEFT.br_blockcount += PREV.br_blockcount + RIGHT.br_blockcount;
  
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_prev(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &LEFT);
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  				XFS_IFORK_NEXTENTS(ip, whichfork) - 2);
  		if (cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(cur, &RIGHT, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			if ((error = xfs_btree_delete(cur, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			if ((error = xfs_btree_decrement(cur, 0, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			if ((error = xfs_btree_delete(cur, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			if ((error = xfs_btree_decrement(cur, 0, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &LEFT);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
  		/*
  		 * Setting all of a previous oldext extent to newext.
  		 * The left neighbor is contiguous, the right is not.
  		 */
  		LEFT.br_blockcount += PREV.br_blockcount;
  
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_prev(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &LEFT);
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
  		if (cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(cur, &PREV, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			if ((error = xfs_btree_delete(cur, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			if ((error = xfs_btree_decrement(cur, 0, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &LEFT);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
  		/*
  		 * Setting all of a previous oldext extent to newext.
  		 * The right neighbor is contiguous, the left is not.
  		 */
  		PREV.br_blockcount += RIGHT.br_blockcount;
  		PREV.br_state = new->br_state;
  
  		xfs_iext_next(ifp, icur);
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_prev(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &PREV);
  
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  				XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
  		if (cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(cur, &RIGHT, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			if ((error = xfs_btree_delete(cur, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			if ((error = xfs_btree_decrement(cur, 0, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &PREV);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
  		/*
  		 * Setting all of a previous oldext extent to newext.
  		 * Neither the left nor right neighbors are contiguous with
  		 * the new one.
  		 */
  		PREV.br_state = new->br_state;
  		xfs_iext_update_extent(ip, state, icur, &PREV);
  
  		if (cur == NULL)
  			rval = XFS_ILOG_DEXT;
  		else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(cur, new, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &PREV);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG:
  		/*
  		 * Setting the first part of a previous oldext extent to newext.
  		 * The left neighbor is contiguous.
  		 */
  		LEFT.br_blockcount += new->br_blockcount;
  
  		old = PREV;
  		PREV.br_startoff += new->br_blockcount;
  		PREV.br_startblock += new->br_blockcount;
  		PREV.br_blockcount -= new->br_blockcount;
  
  		xfs_iext_update_extent(ip, state, icur, &PREV);
  		xfs_iext_prev(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &LEFT);
  
  		if (cur == NULL)
  			rval = XFS_ILOG_DEXT;
  		else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &PREV);
  			if (error)
  				goto done;
  			error = xfs_btree_decrement(cur, 0, &i);
  			if (error)
  				goto done;
  			error = xfs_bmbt_update(cur, &LEFT);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_FILLING:
  		/*
  		 * Setting the first part of a previous oldext extent to newext.
  		 * The left neighbor is not contiguous.
  		 */
  		old = PREV;
  		PREV.br_startoff += new->br_blockcount;
  		PREV.br_startblock += new->br_blockcount;
  		PREV.br_blockcount -= new->br_blockcount;
  
  		xfs_iext_update_extent(ip, state, icur, &PREV);
  		xfs_iext_insert(ip, icur, new, state);
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
  		if (cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &PREV);
  			if (error)
  				goto done;
  			cur->bc_rec.b = *new;
  			if ((error = xfs_btree_insert(cur, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		}
  		break;
  
  	case BMAP_RIGHT_FILLING | BMAP_RIGHT_CONTIG:
  		/*
  		 * Setting the last part of a previous oldext extent to newext.
  		 * The right neighbor is contiguous with the new allocation.
  		 */
  		old = PREV;
  		PREV.br_blockcount -= new->br_blockcount;
  
  		RIGHT.br_startoff = new->br_startoff;
  		RIGHT.br_startblock = new->br_startblock;
  		RIGHT.br_blockcount += new->br_blockcount;
  
  		xfs_iext_update_extent(ip, state, icur, &PREV);
  		xfs_iext_next(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &RIGHT);
  
  		if (cur == NULL)
  			rval = XFS_ILOG_DEXT;
  		else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &PREV);
  			if (error)
  				goto done;
  			error = xfs_btree_increment(cur, 0, &i);
  			if (error)
  				goto done;
  			error = xfs_bmbt_update(cur, &RIGHT);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_RIGHT_FILLING:
  		/*
  		 * Setting the last part of a previous oldext extent to newext.
  		 * The right neighbor is not contiguous.
  		 */
  		old = PREV;
  		PREV.br_blockcount -= new->br_blockcount;
  
  		xfs_iext_update_extent(ip, state, icur, &PREV);
  		xfs_iext_next(ifp, icur);
  		xfs_iext_insert(ip, icur, new, state);
  
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  				XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
  		if (cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &PREV);
  			if (error)
  				goto done;
  			error = xfs_bmbt_lookup_eq(cur, new, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
  			if ((error = xfs_btree_insert(cur, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		}
  		break;
  
  	case 0:
  		/*
  		 * Setting the middle part of a previous oldext extent to
  		 * newext.  Contiguity is impossible here.
  		 * One extent becomes three extents.
  		 */
  		old = PREV;
  		PREV.br_blockcount = new->br_startoff - PREV.br_startoff;
  
  		r[0] = *new;
  		r[1].br_startoff = new_endoff;
  		r[1].br_blockcount =
  			old.br_startoff + old.br_blockcount - new_endoff;
  		r[1].br_startblock = new->br_startblock + new->br_blockcount;
  		r[1].br_state = PREV.br_state;
  
  		xfs_iext_update_extent(ip, state, icur, &PREV);
  		xfs_iext_next(ifp, icur);
  		xfs_iext_insert(ip, icur, &r[1], state);
  		xfs_iext_insert(ip, icur, &r[0], state);
  
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  				XFS_IFORK_NEXTENTS(ip, whichfork) + 2);
  		if (cur == NULL)
  			rval = XFS_ILOG_CORE | XFS_ILOG_DEXT;
  		else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			/* new right extent - oldext */
  			error = xfs_bmbt_update(cur, &r[1]);
  			if (error)
  				goto done;
  			/* new left extent - oldext */
  			cur->bc_rec.b = PREV;
  			if ((error = xfs_btree_insert(cur, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			/*
  			 * Reset the cursor to the position of the new extent
  			 * we are about to insert as we can't trust it after
  			 * the previous insert.
  			 */
  			error = xfs_bmbt_lookup_eq(cur, new, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
  			/* new middle extent - newext */
  			if ((error = xfs_btree_insert(cur, &i)))
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		}
  		break;
  
  	case BMAP_LEFT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
  	case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_CONTIG:
  	case BMAP_RIGHT_FILLING | BMAP_LEFT_CONTIG:
  	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
  	case BMAP_LEFT_CONTIG:
  	case BMAP_RIGHT_CONTIG:
  		/*
  		 * These cases are all impossible.
  		 */
  		ASSERT(0);
  	}
  
  	/* update reverse mappings */
  	error = xfs_rmap_convert_extent(mp, tp, ip, whichfork, new);
  	if (error)
  		goto done;
  
  	/* convert to a btree if necessary */
  	if (xfs_bmap_needs_btree(ip, whichfork)) {
  		int	tmp_logflags;	/* partial log flag return val */
  
  		ASSERT(cur == NULL);
  		error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
  				&tmp_logflags, whichfork);
  		*logflagsp |= tmp_logflags;
  		if (error)
  			goto done;
  	}
  
  	/* clear out the allocated field, done with it now in any case. */
  	if (cur) {
  		cur->bc_private.b.allocated = 0;
  		*curp = cur;
  	}
  
  	xfs_bmap_check_leaf_extents(*curp, ip, whichfork);
  done:
  	*logflagsp |= rval;
  	return error;
  #undef	LEFT
  #undef	RIGHT
  #undef	PREV
  }
  
  /*
   * Convert a hole to a delayed allocation.
   */
  STATIC void
  xfs_bmap_add_extent_hole_delay(
  	xfs_inode_t		*ip,	/* incore inode pointer */
  	int			whichfork,
  	struct xfs_iext_cursor	*icur,
  	xfs_bmbt_irec_t		*new)	/* new data to add to file extents */
  {
  	struct xfs_ifork	*ifp;	/* inode fork pointer */
  	xfs_bmbt_irec_t		left;	/* left neighbor extent entry */
  	xfs_filblks_t		newlen=0;	/* new indirect size */
  	xfs_filblks_t		oldlen=0;	/* old indirect size */
  	xfs_bmbt_irec_t		right;	/* right neighbor extent entry */
  	int			state = xfs_bmap_fork_to_state(whichfork);
  	xfs_filblks_t		temp;	 /* temp for indirect calculations */
  
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	ASSERT(isnullstartblock(new->br_startblock));
  
  	/*
  	 * Check and set flags if this segment has a left neighbor
  	 */
  	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
  		state |= BMAP_LEFT_VALID;
  		if (isnullstartblock(left.br_startblock))
  			state |= BMAP_LEFT_DELAY;
  	}
  
  	/*
  	 * Check and set flags if the current (right) segment exists.
  	 * If it doesn't exist, we're converting the hole at end-of-file.
  	 */
  	if (xfs_iext_get_extent(ifp, icur, &right)) {
  		state |= BMAP_RIGHT_VALID;
  		if (isnullstartblock(right.br_startblock))
  			state |= BMAP_RIGHT_DELAY;
  	}
  
  	/*
  	 * Set contiguity flags on the left and right neighbors.
  	 * Don't let extents get too large, even if the pieces are contiguous.
  	 */
  	if ((state & BMAP_LEFT_VALID) && (state & BMAP_LEFT_DELAY) &&
  	    left.br_startoff + left.br_blockcount == new->br_startoff &&
  	    left.br_blockcount + new->br_blockcount <= MAXEXTLEN)
  		state |= BMAP_LEFT_CONTIG;
  
  	if ((state & BMAP_RIGHT_VALID) && (state & BMAP_RIGHT_DELAY) &&
  	    new->br_startoff + new->br_blockcount == right.br_startoff &&
  	    new->br_blockcount + right.br_blockcount <= MAXEXTLEN &&
  	    (!(state & BMAP_LEFT_CONTIG) ||
  	     (left.br_blockcount + new->br_blockcount +
  	      right.br_blockcount <= MAXEXTLEN)))
  		state |= BMAP_RIGHT_CONTIG;
  
  	/*
  	 * Switch out based on the contiguity flags.
  	 */
  	switch (state & (BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG)) {
  	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
  		/*
  		 * New allocation is contiguous with delayed allocations
  		 * on the left and on the right.
  		 * Merge all three into a single extent record.
  		 */
  		temp = left.br_blockcount + new->br_blockcount +
  			right.br_blockcount;
  
  		oldlen = startblockval(left.br_startblock) +
  			startblockval(new->br_startblock) +
  			startblockval(right.br_startblock);
  		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
  					 oldlen);
  		left.br_startblock = nullstartblock(newlen);
  		left.br_blockcount = temp;
  
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_prev(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &left);
  		break;
  
  	case BMAP_LEFT_CONTIG:
  		/*
  		 * New allocation is contiguous with a delayed allocation
  		 * on the left.
  		 * Merge the new allocation with the left neighbor.
  		 */
  		temp = left.br_blockcount + new->br_blockcount;
  
  		oldlen = startblockval(left.br_startblock) +
  			startblockval(new->br_startblock);
  		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
  					 oldlen);
  		left.br_blockcount = temp;
  		left.br_startblock = nullstartblock(newlen);
  
  		xfs_iext_prev(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &left);
  		break;
  
  	case BMAP_RIGHT_CONTIG:
  		/*
  		 * New allocation is contiguous with a delayed allocation
  		 * on the right.
  		 * Merge the new allocation with the right neighbor.
  		 */
  		temp = new->br_blockcount + right.br_blockcount;
  		oldlen = startblockval(new->br_startblock) +
  			startblockval(right.br_startblock);
  		newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
  					 oldlen);
  		right.br_startoff = new->br_startoff;
  		right.br_startblock = nullstartblock(newlen);
  		right.br_blockcount = temp;
  		xfs_iext_update_extent(ip, state, icur, &right);
  		break;
  
  	case 0:
  		/*
  		 * New allocation is not contiguous with another
  		 * delayed allocation.
  		 * Insert a new entry.
  		 */
  		oldlen = newlen = 0;
  		xfs_iext_insert(ip, icur, new, state);
  		break;
  	}
  	if (oldlen != newlen) {
  		ASSERT(oldlen > newlen);
  		xfs_mod_fdblocks(ip->i_mount, (int64_t)(oldlen - newlen),
  				 false);
  		/*
  		 * Nothing to do for disk quota accounting here.
  		 */
  		xfs_mod_delalloc(ip->i_mount, (int64_t)newlen - oldlen);
  	}
  }
  
  /*
   * Convert a hole to a real allocation.
   */
  STATIC int				/* error */
  xfs_bmap_add_extent_hole_real(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	int			whichfork,
  	struct xfs_iext_cursor	*icur,
  	struct xfs_btree_cur	**curp,
  	struct xfs_bmbt_irec	*new,
  	int			*logflagsp,
  	int			flags)
  {
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_btree_cur	*cur = *curp;
  	int			error;	/* error return value */
  	int			i;	/* temp state */
  	xfs_bmbt_irec_t		left;	/* left neighbor extent entry */
  	xfs_bmbt_irec_t		right;	/* right neighbor extent entry */
  	int			rval=0;	/* return value (logging flags) */
  	int			state = xfs_bmap_fork_to_state(whichfork);
  	struct xfs_bmbt_irec	old;
  
  	ASSERT(!isnullstartblock(new->br_startblock));
  	ASSERT(!cur || !(cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL));
  
  	XFS_STATS_INC(mp, xs_add_exlist);
  
  	/*
  	 * Check and set flags if this segment has a left neighbor.
  	 */
  	if (xfs_iext_peek_prev_extent(ifp, icur, &left)) {
  		state |= BMAP_LEFT_VALID;
  		if (isnullstartblock(left.br_startblock))
  			state |= BMAP_LEFT_DELAY;
  	}
  
  	/*
  	 * Check and set flags if this segment has a current value.
  	 * Not true if we're inserting into the "hole" at eof.
  	 */
  	if (xfs_iext_get_extent(ifp, icur, &right)) {
  		state |= BMAP_RIGHT_VALID;
  		if (isnullstartblock(right.br_startblock))
  			state |= BMAP_RIGHT_DELAY;
  	}
  
  	/*
  	 * We're inserting a real allocation between "left" and "right".
  	 * Set the contiguity flags.  Don't let extents get too large.
  	 */
  	if ((state & BMAP_LEFT_VALID) && !(state & BMAP_LEFT_DELAY) &&
  	    left.br_startoff + left.br_blockcount == new->br_startoff &&
  	    left.br_startblock + left.br_blockcount == new->br_startblock &&
  	    left.br_state == new->br_state &&
  	    left.br_blockcount + new->br_blockcount <= MAXEXTLEN)
  		state |= BMAP_LEFT_CONTIG;
  
  	if ((state & BMAP_RIGHT_VALID) && !(state & BMAP_RIGHT_DELAY) &&
  	    new->br_startoff + new->br_blockcount == right.br_startoff &&
  	    new->br_startblock + new->br_blockcount == right.br_startblock &&
  	    new->br_state == right.br_state &&
  	    new->br_blockcount + right.br_blockcount <= MAXEXTLEN &&
  	    (!(state & BMAP_LEFT_CONTIG) ||
  	     left.br_blockcount + new->br_blockcount +
  	     right.br_blockcount <= MAXEXTLEN))
  		state |= BMAP_RIGHT_CONTIG;
  
  	error = 0;
  	/*
  	 * Select which case we're in here, and implement it.
  	 */
  	switch (state & (BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG)) {
  	case BMAP_LEFT_CONTIG | BMAP_RIGHT_CONTIG:
  		/*
  		 * New allocation is contiguous with real allocations on the
  		 * left and on the right.
  		 * Merge all three into a single extent record.
  		 */
  		left.br_blockcount += new->br_blockcount + right.br_blockcount;
  
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_prev(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &left);
  
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
  		if (cur == NULL) {
  			rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
  		} else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(cur, &right, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_btree_delete(cur, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_btree_decrement(cur, 0, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &left);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_LEFT_CONTIG:
  		/*
  		 * New allocation is contiguous with a real allocation
  		 * on the left.
  		 * Merge the new allocation with the left neighbor.
  		 */
  		old = left;
  		left.br_blockcount += new->br_blockcount;
  
  		xfs_iext_prev(ifp, icur);
  		xfs_iext_update_extent(ip, state, icur, &left);
  
  		if (cur == NULL) {
  			rval = xfs_ilog_fext(whichfork);
  		} else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &left);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case BMAP_RIGHT_CONTIG:
  		/*
  		 * New allocation is contiguous with a real allocation
  		 * on the right.
  		 * Merge the new allocation with the right neighbor.
  		 */
  		old = right;
  
  		right.br_startoff = new->br_startoff;
  		right.br_startblock = new->br_startblock;
  		right.br_blockcount += new->br_blockcount;
  		xfs_iext_update_extent(ip, state, icur, &right);
  
  		if (cur == NULL) {
  			rval = xfs_ilog_fext(whichfork);
  		} else {
  			rval = 0;
  			error = xfs_bmbt_lookup_eq(cur, &old, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  			error = xfs_bmbt_update(cur, &right);
  			if (error)
  				goto done;
  		}
  		break;
  
  	case 0:
  		/*
  		 * New allocation is not contiguous with another
  		 * real allocation.
  		 * Insert a new entry.
  		 */
  		xfs_iext_insert(ip, icur, new, state);
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
  		if (cur == NULL) {
  			rval = XFS_ILOG_CORE | xfs_ilog_fext(whichfork);
  		} else {
  			rval = XFS_ILOG_CORE;
  			error = xfs_bmbt_lookup_eq(cur, new, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 0, done);
  			error = xfs_btree_insert(cur, &i);
  			if (error)
  				goto done;
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		}
  		break;
  	}
  
  	/* add reverse mapping unless caller opted out */
  	if (!(flags & XFS_BMAPI_NORMAP)) {
  		error = xfs_rmap_map_extent(tp, ip, whichfork, new);
  		if (error)
  			goto done;
  	}
  
  	/* convert to a btree if necessary */
  	if (xfs_bmap_needs_btree(ip, whichfork)) {
  		int	tmp_logflags;	/* partial log flag return val */
  
  		ASSERT(cur == NULL);
  		error = xfs_bmap_extents_to_btree(tp, ip, curp, 0,
  				&tmp_logflags, whichfork);
  		*logflagsp |= tmp_logflags;
  		cur = *curp;
  		if (error)
  			goto done;
  	}
  
  	/* clear out the allocated field, done with it now in any case. */
  	if (cur)
  		cur->bc_private.b.allocated = 0;
  
  	xfs_bmap_check_leaf_extents(cur, ip, whichfork);
  done:
  	*logflagsp |= rval;
  	return error;
  }
  
  /*
   * Functions used in the extent read, allocate and remove paths
   */
  
  /*
   * Adjust the size of the new extent based on di_extsize and rt extsize.
   */
  int
  xfs_bmap_extsize_align(
  	xfs_mount_t	*mp,
  	xfs_bmbt_irec_t	*gotp,		/* next extent pointer */
  	xfs_bmbt_irec_t	*prevp,		/* previous extent pointer */
  	xfs_extlen_t	extsz,		/* align to this extent size */
  	int		rt,		/* is this a realtime inode? */
  	int		eof,		/* is extent at end-of-file? */
  	int		delay,		/* creating delalloc extent? */
  	int		convert,	/* overwriting unwritten extent? */
  	xfs_fileoff_t	*offp,		/* in/out: aligned offset */
  	xfs_extlen_t	*lenp)		/* in/out: aligned length */
  {
  	xfs_fileoff_t	orig_off;	/* original offset */
  	xfs_extlen_t	orig_alen;	/* original length */
  	xfs_fileoff_t	orig_end;	/* original off+len */
  	xfs_fileoff_t	nexto;		/* next file offset */
  	xfs_fileoff_t	prevo;		/* previous file offset */
  	xfs_fileoff_t	align_off;	/* temp for offset */
  	xfs_extlen_t	align_alen;	/* temp for length */
  	xfs_extlen_t	temp;		/* temp for calculations */
  
  	if (convert)
  		return 0;
  
  	orig_off = align_off = *offp;
  	orig_alen = align_alen = *lenp;
  	orig_end = orig_off + orig_alen;
  
  	/*
  	 * If this request overlaps an existing extent, then don't
  	 * attempt to perform any additional alignment.
  	 */
  	if (!delay && !eof &&
  	    (orig_off >= gotp->br_startoff) &&
  	    (orig_end <= gotp->br_startoff + gotp->br_blockcount)) {
  		return 0;
  	}
  
  	/*
  	 * If the file offset is unaligned vs. the extent size
  	 * we need to align it.  This will be possible unless
  	 * the file was previously written with a kernel that didn't
  	 * perform this alignment, or if a truncate shot us in the
  	 * foot.
  	 */
  	div_u64_rem(orig_off, extsz, &temp);
  	if (temp) {
  		align_alen += temp;
  		align_off -= temp;
  	}
  
  	/* Same adjustment for the end of the requested area. */
  	temp = (align_alen % extsz);
  	if (temp)
  		align_alen += extsz - temp;
  
  	/*
  	 * For large extent hint sizes, the aligned extent might be larger than
  	 * MAXEXTLEN. In that case, reduce the size by an extsz so that it pulls
  	 * the length back under MAXEXTLEN. The outer allocation loops handle
  	 * short allocation just fine, so it is safe to do this. We only want to
  	 * do it when we are forced to, though, because it means more allocation
  	 * operations are required.
  	 */
  	while (align_alen > MAXEXTLEN)
  		align_alen -= extsz;
  	ASSERT(align_alen <= MAXEXTLEN);
  
  	/*
  	 * If the previous block overlaps with this proposed allocation
  	 * then move the start forward without adjusting the length.
  	 */
  	if (prevp->br_startoff != NULLFILEOFF) {
  		if (prevp->br_startblock == HOLESTARTBLOCK)
  			prevo = prevp->br_startoff;
  		else
  			prevo = prevp->br_startoff + prevp->br_blockcount;
  	} else
  		prevo = 0;
  	if (align_off != orig_off && align_off < prevo)
  		align_off = prevo;
  	/*
  	 * If the next block overlaps with this proposed allocation
  	 * then move the start back without adjusting the length,
  	 * but not before offset 0.
  	 * This may of course make the start overlap previous block,
  	 * and if we hit the offset 0 limit then the next block
  	 * can still overlap too.
  	 */
  	if (!eof && gotp->br_startoff != NULLFILEOFF) {
  		if ((delay && gotp->br_startblock == HOLESTARTBLOCK) ||
  		    (!delay && gotp->br_startblock == DELAYSTARTBLOCK))
  			nexto = gotp->br_startoff + gotp->br_blockcount;
  		else
  			nexto = gotp->br_startoff;
  	} else
  		nexto = NULLFILEOFF;
  	if (!eof &&
  	    align_off + align_alen != orig_end &&
  	    align_off + align_alen > nexto)
  		align_off = nexto > align_alen ? nexto - align_alen : 0;
  	/*
  	 * If we're now overlapping the next or previous extent that
  	 * means we can't fit an extsz piece in this hole.  Just move
  	 * the start forward to the first valid spot and set
  	 * the length so we hit the end.
  	 */
  	if (align_off != orig_off && align_off < prevo)
  		align_off = prevo;
  	if (align_off + align_alen != orig_end &&
  	    align_off + align_alen > nexto &&
  	    nexto != NULLFILEOFF) {
  		ASSERT(nexto > prevo);
  		align_alen = nexto - align_off;
  	}
  
  	/*
  	 * If realtime, and the result isn't a multiple of the realtime
  	 * extent size we need to remove blocks until it is.
  	 */
  	if (rt && (temp = (align_alen % mp->m_sb.sb_rextsize))) {
  		/*
  		 * We're not covering the original request, or
  		 * we won't be able to once we fix the length.
  		 */
  		if (orig_off < align_off ||
  		    orig_end > align_off + align_alen ||
  		    align_alen - temp < orig_alen)
  			return -EINVAL;
  		/*
  		 * Try to fix it by moving the start up.
  		 */
  		if (align_off + temp <= orig_off) {
  			align_alen -= temp;
  			align_off += temp;
  		}
  		/*
  		 * Try to fix it by moving the end in.
  		 */
  		else if (align_off + align_alen - temp >= orig_end)
  			align_alen -= temp;
  		/*
  		 * Set the start to the minimum then trim the length.
  		 */
  		else {
  			align_alen -= orig_off - align_off;
  			align_off = orig_off;
  			align_alen -= align_alen % mp->m_sb.sb_rextsize;
  		}
  		/*
  		 * Result doesn't cover the request, fail it.
  		 */
  		if (orig_off < align_off || orig_end > align_off + align_alen)
  			return -EINVAL;
  	} else {
  		ASSERT(orig_off >= align_off);
  		/* see MAXEXTLEN handling above */
  		ASSERT(orig_end <= align_off + align_alen ||
  		       align_alen + extsz > MAXEXTLEN);
  	}
  
  #ifdef DEBUG
  	if (!eof && gotp->br_startoff != NULLFILEOFF)
  		ASSERT(align_off + align_alen <= gotp->br_startoff);
  	if (prevp->br_startoff != NULLFILEOFF)
  		ASSERT(align_off >= prevp->br_startoff + prevp->br_blockcount);
  #endif
  
  	*lenp = align_alen;
  	*offp = align_off;
  	return 0;
  }
  
  #define XFS_ALLOC_GAP_UNITS	4
  
  void
  xfs_bmap_adjacent(
  	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
  {
  	xfs_fsblock_t	adjust;		/* adjustment to block numbers */
  	xfs_agnumber_t	fb_agno;	/* ag number of ap->firstblock */
  	xfs_mount_t	*mp;		/* mount point structure */
  	int		nullfb;		/* true if ap->firstblock isn't set */
  	int		rt;		/* true if inode is realtime */
  
  #define	ISVALID(x,y)	\
  	(rt ? \
  		(x) < mp->m_sb.sb_rblocks : \
  		XFS_FSB_TO_AGNO(mp, x) == XFS_FSB_TO_AGNO(mp, y) && \
  		XFS_FSB_TO_AGNO(mp, x) < mp->m_sb.sb_agcount && \
  		XFS_FSB_TO_AGBNO(mp, x) < mp->m_sb.sb_agblocks)
  
  	mp = ap->ip->i_mount;
  	nullfb = ap->tp->t_firstblock == NULLFSBLOCK;
  	rt = XFS_IS_REALTIME_INODE(ap->ip) &&
  		xfs_alloc_is_userdata(ap->datatype);
  	fb_agno = nullfb ? NULLAGNUMBER : XFS_FSB_TO_AGNO(mp,
  							ap->tp->t_firstblock);
  	/*
  	 * If allocating at eof, and there's a previous real block,
  	 * try to use its last block as our starting point.
  	 */
  	if (ap->eof && ap->prev.br_startoff != NULLFILEOFF &&
  	    !isnullstartblock(ap->prev.br_startblock) &&
  	    ISVALID(ap->prev.br_startblock + ap->prev.br_blockcount,
  		    ap->prev.br_startblock)) {
  		ap->blkno = ap->prev.br_startblock + ap->prev.br_blockcount;
  		/*
  		 * Adjust for the gap between prevp and us.
  		 */
  		adjust = ap->offset -
  			(ap->prev.br_startoff + ap->prev.br_blockcount);
  		if (adjust &&
  		    ISVALID(ap->blkno + adjust, ap->prev.br_startblock))
  			ap->blkno += adjust;
  	}
  	/*
  	 * If not at eof, then compare the two neighbor blocks.
  	 * Figure out whether either one gives us a good starting point,
  	 * and pick the better one.
  	 */
  	else if (!ap->eof) {
  		xfs_fsblock_t	gotbno;		/* right side block number */
  		xfs_fsblock_t	gotdiff=0;	/* right side difference */
  		xfs_fsblock_t	prevbno;	/* left side block number */
  		xfs_fsblock_t	prevdiff=0;	/* left side difference */
  
  		/*
  		 * If there's a previous (left) block, select a requested
  		 * start block based on it.
  		 */
  		if (ap->prev.br_startoff != NULLFILEOFF &&
  		    !isnullstartblock(ap->prev.br_startblock) &&
  		    (prevbno = ap->prev.br_startblock +
  			       ap->prev.br_blockcount) &&
  		    ISVALID(prevbno, ap->prev.br_startblock)) {
  			/*
  			 * Calculate gap to end of previous block.
  			 */
  			adjust = prevdiff = ap->offset -
  				(ap->prev.br_startoff +
  				 ap->prev.br_blockcount);
  			/*
  			 * Figure the startblock based on the previous block's
  			 * end and the gap size.
  			 * Heuristic!
  			 * If the gap is large relative to the piece we're
  			 * allocating, or using it gives us an invalid block
  			 * number, then just use the end of the previous block.
  			 */
  			if (prevdiff <= XFS_ALLOC_GAP_UNITS * ap->length &&
  			    ISVALID(prevbno + prevdiff,
  				    ap->prev.br_startblock))
  				prevbno += adjust;
  			else
  				prevdiff += adjust;
  			/*
  			 * If the firstblock forbids it, can't use it,
  			 * must use default.
  			 */
  			if (!rt && !nullfb &&
  			    XFS_FSB_TO_AGNO(mp, prevbno) != fb_agno)
  				prevbno = NULLFSBLOCK;
  		}
  		/*
  		 * No previous block or can't follow it, just default.
  		 */
  		else
  			prevbno = NULLFSBLOCK;
  		/*
  		 * If there's a following (right) block, select a requested
  		 * start block based on it.
  		 */
  		if (!isnullstartblock(ap->got.br_startblock)) {
  			/*
  			 * Calculate gap to start of next block.
  			 */
  			adjust = gotdiff = ap->got.br_startoff - ap->offset;
  			/*
  			 * Figure the startblock based on the next block's
  			 * start and the gap size.
  			 */
  			gotbno = ap->got.br_startblock;
  			/*
  			 * Heuristic!
  			 * If the gap is large relative to the piece we're
  			 * allocating, or using it gives us an invalid block
  			 * number, then just use the start of the next block
  			 * offset by our length.
  			 */
  			if (gotdiff <= XFS_ALLOC_GAP_UNITS * ap->length &&
  			    ISVALID(gotbno - gotdiff, gotbno))
  				gotbno -= adjust;
  			else if (ISVALID(gotbno - ap->length, gotbno)) {
  				gotbno -= ap->length;
  				gotdiff += adjust - ap->length;
  			} else
  				gotdiff += adjust;
  			/*
  			 * If the firstblock forbids it, can't use it,
  			 * must use default.
  			 */
  			if (!rt && !nullfb &&
  			    XFS_FSB_TO_AGNO(mp, gotbno) != fb_agno)
  				gotbno = NULLFSBLOCK;
  		}
  		/*
  		 * No next block, just default.
  		 */
  		else
  			gotbno = NULLFSBLOCK;
  		/*
  		 * If both valid, pick the better one, else the only good
  		 * one, else ap->blkno is already set (to 0 or the inode block).
  		 */
  		if (prevbno != NULLFSBLOCK && gotbno != NULLFSBLOCK)
  			ap->blkno = prevdiff <= gotdiff ? prevbno : gotbno;
  		else if (prevbno != NULLFSBLOCK)
  			ap->blkno = prevbno;
  		else if (gotbno != NULLFSBLOCK)
  			ap->blkno = gotbno;
  	}
  #undef ISVALID
  }
  
  static int
  xfs_bmap_longest_free_extent(
  	struct xfs_trans	*tp,
  	xfs_agnumber_t		ag,
  	xfs_extlen_t		*blen,
  	int			*notinit)
  {
  	struct xfs_mount	*mp = tp->t_mountp;
  	struct xfs_perag	*pag;
  	xfs_extlen_t		longest;
  	int			error = 0;
  
  	pag = xfs_perag_get(mp, ag);
  	if (!pag->pagf_init) {
  		error = xfs_alloc_pagf_init(mp, tp, ag, XFS_ALLOC_FLAG_TRYLOCK);
  		if (error)
  			goto out;
  
  		if (!pag->pagf_init) {
  			*notinit = 1;
  			goto out;
  		}
  	}
  
  	longest = xfs_alloc_longest_free_extent(pag,
  				xfs_alloc_min_freelist(mp, pag),
  				xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE));
  	if (*blen < longest)
  		*blen = longest;
  
  out:
  	xfs_perag_put(pag);
  	return error;
  }
  
  static void
  xfs_bmap_select_minlen(
  	struct xfs_bmalloca	*ap,
  	struct xfs_alloc_arg	*args,
  	xfs_extlen_t		*blen,
  	int			notinit)
  {
  	if (notinit || *blen < ap->minlen) {
  		/*
  		 * Since we did a BUF_TRYLOCK above, it is possible that
  		 * there is space for this request.
  		 */
  		args->minlen = ap->minlen;
  	} else if (*blen < args->maxlen) {
  		/*
  		 * If the best seen length is less than the request length,
  		 * use the best as the minimum.
  		 */
  		args->minlen = *blen;
  	} else {
  		/*
  		 * Otherwise we've seen an extent as big as maxlen, use that
  		 * as the minimum.
  		 */
  		args->minlen = args->maxlen;
  	}
  }
  
  STATIC int
  xfs_bmap_btalloc_nullfb(
  	struct xfs_bmalloca	*ap,
  	struct xfs_alloc_arg	*args,
  	xfs_extlen_t		*blen)
  {
  	struct xfs_mount	*mp = ap->ip->i_mount;
  	xfs_agnumber_t		ag, startag;
  	int			notinit = 0;
  	int			error;
  
  	args->type = XFS_ALLOCTYPE_START_BNO;
  	args->total = ap->total;
  
  	startag = ag = XFS_FSB_TO_AGNO(mp, args->fsbno);
  	if (startag == NULLAGNUMBER)
  		startag = ag = 0;
  
  	while (*blen < args->maxlen) {
  		error = xfs_bmap_longest_free_extent(args->tp, ag, blen,
  						     &notinit);
  		if (error)
  			return error;
  
  		if (++ag == mp->m_sb.sb_agcount)
  			ag = 0;
  		if (ag == startag)
  			break;
  	}
  
  	xfs_bmap_select_minlen(ap, args, blen, notinit);
  	return 0;
  }
  
  STATIC int
  xfs_bmap_btalloc_filestreams(
  	struct xfs_bmalloca	*ap,
  	struct xfs_alloc_arg	*args,
  	xfs_extlen_t		*blen)
  {
  	struct xfs_mount	*mp = ap->ip->i_mount;
  	xfs_agnumber_t		ag;
  	int			notinit = 0;
  	int			error;
  
  	args->type = XFS_ALLOCTYPE_NEAR_BNO;
  	args->total = ap->total;
  
  	ag = XFS_FSB_TO_AGNO(mp, args->fsbno);
  	if (ag == NULLAGNUMBER)
  		ag = 0;
  
  	error = xfs_bmap_longest_free_extent(args->tp, ag, blen, &notinit);
  	if (error)
  		return error;
  
  	if (*blen < args->maxlen) {
  		error = xfs_filestream_new_ag(ap, &ag);
  		if (error)
  			return error;
  
  		error = xfs_bmap_longest_free_extent(args->tp, ag, blen,
  						     &notinit);
  		if (error)
  			return error;
  
  	}
  
  	xfs_bmap_select_minlen(ap, args, blen, notinit);
  
  	/*
  	 * Set the failure fallback case to look in the selected AG as stream
  	 * may have moved.
  	 */
  	ap->blkno = args->fsbno = XFS_AGB_TO_FSB(mp, ag, 0);
  	return 0;
  }
  
  /* Update all inode and quota accounting for the allocation we just did. */
  static void
  xfs_bmap_btalloc_accounting(
  	struct xfs_bmalloca	*ap,
  	struct xfs_alloc_arg	*args)
  {
  	if (ap->flags & XFS_BMAPI_COWFORK) {
  		/*
  		 * COW fork blocks are in-core only and thus are treated as
  		 * in-core quota reservation (like delalloc blocks) even when
  		 * converted to real blocks. The quota reservation is not
  		 * accounted to disk until blocks are remapped to the data
  		 * fork. So if these blocks were previously delalloc, we
  		 * already have quota reservation and there's nothing to do
  		 * yet.
  		 */
  		if (ap->wasdel) {
  			xfs_mod_delalloc(ap->ip->i_mount, -(int64_t)args->len);
  			return;
  		}
  
  		/*
  		 * Otherwise, we've allocated blocks in a hole. The transaction
  		 * has acquired in-core quota reservation for this extent.
  		 * Rather than account these as real blocks, however, we reduce
  		 * the transaction quota reservation based on the allocation.
  		 * This essentially transfers the transaction quota reservation
  		 * to that of a delalloc extent.
  		 */
  		ap->ip->i_delayed_blks += args->len;
  		xfs_trans_mod_dquot_byino(ap->tp, ap->ip, XFS_TRANS_DQ_RES_BLKS,
  				-(long)args->len);
  		return;
  	}
  
  	/* data/attr fork only */
  	ap->ip->i_d.di_nblocks += args->len;
  	xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
  	if (ap->wasdel) {
  		ap->ip->i_delayed_blks -= args->len;
  		xfs_mod_delalloc(ap->ip->i_mount, -(int64_t)args->len);
  	}
  	xfs_trans_mod_dquot_byino(ap->tp, ap->ip,
  		ap->wasdel ? XFS_TRANS_DQ_DELBCOUNT : XFS_TRANS_DQ_BCOUNT,
  		args->len);
  }
  
  STATIC int
  xfs_bmap_btalloc(
  	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
  {
  	xfs_mount_t	*mp;		/* mount point structure */
  	xfs_alloctype_t	atype = 0;	/* type for allocation routines */
  	xfs_extlen_t	align = 0;	/* minimum allocation alignment */
  	xfs_agnumber_t	fb_agno;	/* ag number of ap->firstblock */
  	xfs_agnumber_t	ag;
  	xfs_alloc_arg_t	args;
  	xfs_fileoff_t	orig_offset;
  	xfs_extlen_t	orig_length;
  	xfs_extlen_t	blen;
  	xfs_extlen_t	nextminlen = 0;
  	int		nullfb;		/* true if ap->firstblock isn't set */
  	int		isaligned;
  	int		tryagain;
  	int		error;
  	int		stripe_align;
  
  	ASSERT(ap->length);
  	orig_offset = ap->offset;
  	orig_length = ap->length;
  
  	mp = ap->ip->i_mount;
  
  	/* stripe alignment for allocation is determined by mount parameters */
  	stripe_align = 0;
  	if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
  		stripe_align = mp->m_swidth;
  	else if (mp->m_dalign)
  		stripe_align = mp->m_dalign;
  
  	if (ap->flags & XFS_BMAPI_COWFORK)
  		align = xfs_get_cowextsz_hint(ap->ip);
  	else if (xfs_alloc_is_userdata(ap->datatype))
  		align = xfs_get_extsz_hint(ap->ip);
  	if (align) {
  		error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev,
  						align, 0, ap->eof, 0, ap->conv,
  						&ap->offset, &ap->length);
  		ASSERT(!error);
  		ASSERT(ap->length);
  	}
  
  
  	nullfb = ap->tp->t_firstblock == NULLFSBLOCK;
  	fb_agno = nullfb ? NULLAGNUMBER : XFS_FSB_TO_AGNO(mp,
  							ap->tp->t_firstblock);
  	if (nullfb) {
  		if (xfs_alloc_is_userdata(ap->datatype) &&
  		    xfs_inode_is_filestream(ap->ip)) {
  			ag = xfs_filestream_lookup_ag(ap->ip);
  			ag = (ag != NULLAGNUMBER) ? ag : 0;
  			ap->blkno = XFS_AGB_TO_FSB(mp, ag, 0);
  		} else {
  			ap->blkno = XFS_INO_TO_FSB(mp, ap->ip->i_ino);
  		}
  	} else
  		ap->blkno = ap->tp->t_firstblock;
  
  	xfs_bmap_adjacent(ap);
  
  	/*
  	 * If allowed, use ap->blkno; otherwise must use firstblock since
  	 * it's in the right allocation group.
  	 */
  	if (nullfb || XFS_FSB_TO_AGNO(mp, ap->blkno) == fb_agno)
  		;
  	else
  		ap->blkno = ap->tp->t_firstblock;
  	/*
  	 * Normal allocation, done through xfs_alloc_vextent.
  	 */
  	tryagain = isaligned = 0;
  	memset(&args, 0, sizeof(args));
  	args.tp = ap->tp;
  	args.mp = mp;
  	args.fsbno = ap->blkno;
  	args.oinfo = XFS_RMAP_OINFO_SKIP_UPDATE;
  
  	/* Trim the allocation back to the maximum an AG can fit. */
  	args.maxlen = min(ap->length, mp->m_ag_max_usable);
  	blen = 0;
  	if (nullfb) {
  		/*
  		 * Search for an allocation group with a single extent large
  		 * enough for the request.  If one isn't found, then adjust
  		 * the minimum allocation size to the largest space found.
  		 */
  		if (xfs_alloc_is_userdata(ap->datatype) &&
  		    xfs_inode_is_filestream(ap->ip))
  			error = xfs_bmap_btalloc_filestreams(ap, &args, &blen);
  		else
  			error = xfs_bmap_btalloc_nullfb(ap, &args, &blen);
  		if (error)
  			return error;
  	} else if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
  		if (xfs_inode_is_filestream(ap->ip))
  			args.type = XFS_ALLOCTYPE_FIRST_AG;
  		else
  			args.type = XFS_ALLOCTYPE_START_BNO;
  		args.total = args.minlen = ap->minlen;
  	} else {
  		args.type = XFS_ALLOCTYPE_NEAR_BNO;
  		args.total = ap->total;
  		args.minlen = ap->minlen;
  	}
  	/* apply extent size hints if obtained earlier */
  	if (align) {
  		args.prod = align;
  		div_u64_rem(ap->offset, args.prod, &args.mod);
  		if (args.mod)
  			args.mod = args.prod - args.mod;
  	} else if (mp->m_sb.sb_blocksize >= PAGE_SIZE) {
  		args.prod = 1;
  		args.mod = 0;
  	} else {
  		args.prod = PAGE_SIZE >> mp->m_sb.sb_blocklog;
  		div_u64_rem(ap->offset, args.prod, &args.mod);
  		if (args.mod)
  			args.mod = args.prod - args.mod;
  	}
  	/*
  	 * If we are not low on available data blocks, and the
  	 * underlying logical volume manager is a stripe, and
  	 * the file offset is zero then try to allocate data
  	 * blocks on stripe unit boundary.
  	 * NOTE: ap->aeof is only set if the allocation length
  	 * is >= the stripe unit and the allocation offset is
  	 * at the end of file.
  	 */
  	if (!(ap->tp->t_flags & XFS_TRANS_LOWMODE) && ap->aeof) {
  		if (!ap->offset) {
  			args.alignment = stripe_align;
  			atype = args.type;
  			isaligned = 1;
  			/*
  			 * Adjust for alignment
  			 */
  			if (blen > args.alignment && blen <= args.maxlen)
  				args.minlen = blen - args.alignment;
  			args.minalignslop = 0;
  		} else {
  			/*
  			 * First try an exact bno allocation.
  			 * If it fails then do a near or start bno
  			 * allocation with alignment turned on.
  			 */
  			atype = args.type;
  			tryagain = 1;
  			args.type = XFS_ALLOCTYPE_THIS_BNO;
  			args.alignment = 1;
  			/*
  			 * Compute the minlen+alignment for the
  			 * next case.  Set slop so that the value
  			 * of minlen+alignment+slop doesn't go up
  			 * between the calls.
  			 */
  			if (blen > stripe_align && blen <= args.maxlen)
  				nextminlen = blen - stripe_align;
  			else
  				nextminlen = args.minlen;
  			if (nextminlen + stripe_align > args.minlen + 1)
  				args.minalignslop =
  					nextminlen + stripe_align -
  					args.minlen - 1;
  			else
  				args.minalignslop = 0;
  		}
  	} else {
  		args.alignment = 1;
  		args.minalignslop = 0;
  	}
  	args.minleft = ap->minleft;
  	args.wasdel = ap->wasdel;
  	args.resv = XFS_AG_RESV_NONE;
  	args.datatype = ap->datatype;
  	if (ap->datatype & XFS_ALLOC_USERDATA_ZERO)
  		args.ip = ap->ip;
  
  	error = xfs_alloc_vextent(&args);
  	if (error)
  		return error;
  
  	if (tryagain && args.fsbno == NULLFSBLOCK) {
  		/*
  		 * Exact allocation failed. Now try with alignment
  		 * turned on.
  		 */
  		args.type = atype;
  		args.fsbno = ap->blkno;
  		args.alignment = stripe_align;
  		args.minlen = nextminlen;
  		args.minalignslop = 0;
  		isaligned = 1;
  		if ((error = xfs_alloc_vextent(&args)))
  			return error;
  	}
  	if (isaligned && args.fsbno == NULLFSBLOCK) {
  		/*
  		 * allocation failed, so turn off alignment and
  		 * try again.
  		 */
  		args.type = atype;
  		args.fsbno = ap->blkno;
  		args.alignment = 0;
  		if ((error = xfs_alloc_vextent(&args)))
  			return error;
  	}
  	if (args.fsbno == NULLFSBLOCK && nullfb &&
  	    args.minlen > ap->minlen) {
  		args.minlen = ap->minlen;
  		args.type = XFS_ALLOCTYPE_START_BNO;
  		args.fsbno = ap->blkno;
  		if ((error = xfs_alloc_vextent(&args)))
  			return error;
  	}
  	if (args.fsbno == NULLFSBLOCK && nullfb) {
  		args.fsbno = 0;
  		args.type = XFS_ALLOCTYPE_FIRST_AG;
  		args.total = ap->minlen;
  		if ((error = xfs_alloc_vextent(&args)))
  			return error;
  		ap->tp->t_flags |= XFS_TRANS_LOWMODE;
  	}
  	if (args.fsbno != NULLFSBLOCK) {
  		/*
  		 * check the allocation happened at the same or higher AG than
  		 * the first block that was allocated.
  		 */
  		ASSERT(ap->tp->t_firstblock == NULLFSBLOCK ||
  		       XFS_FSB_TO_AGNO(mp, ap->tp->t_firstblock) <=
  		       XFS_FSB_TO_AGNO(mp, args.fsbno));
  
  		ap->blkno = args.fsbno;
  		if (ap->tp->t_firstblock == NULLFSBLOCK)
  			ap->tp->t_firstblock = args.fsbno;
  		ASSERT(nullfb || fb_agno <= args.agno);
  		ap->length = args.len;
  		/*
  		 * If the extent size hint is active, we tried to round the
  		 * caller's allocation request offset down to extsz and the
  		 * length up to another extsz boundary.  If we found a free
  		 * extent we mapped it in starting at this new offset.  If the
  		 * newly mapped space isn't long enough to cover any of the
  		 * range of offsets that was originally requested, move the
  		 * mapping up so that we can fill as much of the caller's
  		 * original request as possible.  Free space is apparently
  		 * very fragmented so we're unlikely to be able to satisfy the
  		 * hints anyway.
  		 */
  		if (ap->length <= orig_length)
  			ap->offset = orig_offset;
  		else if (ap->offset + ap->length < orig_offset + orig_length)
  			ap->offset = orig_offset + orig_length - ap->length;
  		xfs_bmap_btalloc_accounting(ap, &args);
  	} else {
  		ap->blkno = NULLFSBLOCK;
  		ap->length = 0;
  	}
  	return 0;
  }
  
  /*
   * xfs_bmap_alloc is called by xfs_bmapi to allocate an extent for a file.
   * It figures out where to ask the underlying allocator to put the new extent.
   */
  STATIC int
  xfs_bmap_alloc(
  	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
  {
  	if (XFS_IS_REALTIME_INODE(ap->ip) &&
  	    xfs_alloc_is_userdata(ap->datatype))
  		return xfs_bmap_rtalloc(ap);
  	return xfs_bmap_btalloc(ap);
  }
  
  /* Trim extent to fit a logical block range. */
  void
  xfs_trim_extent(
  	struct xfs_bmbt_irec	*irec,
  	xfs_fileoff_t		bno,
  	xfs_filblks_t		len)
  {
  	xfs_fileoff_t		distance;
  	xfs_fileoff_t		end = bno + len;
  
  	if (irec->br_startoff + irec->br_blockcount <= bno ||
  	    irec->br_startoff >= end) {
  		irec->br_blockcount = 0;
  		return;
  	}
  
  	if (irec->br_startoff < bno) {
  		distance = bno - irec->br_startoff;
  		if (isnullstartblock(irec->br_startblock))
  			irec->br_startblock = DELAYSTARTBLOCK;
  		if (irec->br_startblock != DELAYSTARTBLOCK &&
  		    irec->br_startblock != HOLESTARTBLOCK)
  			irec->br_startblock += distance;
  		irec->br_startoff += distance;
  		irec->br_blockcount -= distance;
  	}
  
  	if (end < irec->br_startoff + irec->br_blockcount) {
  		distance = irec->br_startoff + irec->br_blockcount - end;
  		irec->br_blockcount -= distance;
  	}
  }
  
  /*
   * Trim the returned map to the required bounds
   */
  STATIC void
  xfs_bmapi_trim_map(
  	struct xfs_bmbt_irec	*mval,
  	struct xfs_bmbt_irec	*got,
  	xfs_fileoff_t		*bno,
  	xfs_filblks_t		len,
  	xfs_fileoff_t		obno,
  	xfs_fileoff_t		end,
  	int			n,
  	int			flags)
  {
  	if ((flags & XFS_BMAPI_ENTIRE) ||
  	    got->br_startoff + got->br_blockcount <= obno) {
  		*mval = *got;
  		if (isnullstartblock(got->br_startblock))
  			mval->br_startblock = DELAYSTARTBLOCK;
  		return;
  	}
  
  	if (obno > *bno)
  		*bno = obno;
  	ASSERT((*bno >= obno) || (n == 0));
  	ASSERT(*bno < end);
  	mval->br_startoff = *bno;
  	if (isnullstartblock(got->br_startblock))
  		mval->br_startblock = DELAYSTARTBLOCK;
  	else
  		mval->br_startblock = got->br_startblock +
  					(*bno - got->br_startoff);
  	/*
  	 * Return the minimum of what we got and what we asked for for
  	 * the length.  We can use the len variable here because it is
  	 * modified below and we could have been there before coming
  	 * here if the first part of the allocation didn't overlap what
  	 * was asked for.
  	 */
  	mval->br_blockcount = XFS_FILBLKS_MIN(end - *bno,
  			got->br_blockcount - (*bno - got->br_startoff));
  	mval->br_state = got->br_state;
  	ASSERT(mval->br_blockcount <= len);
  	return;
  }
  
  /*
   * Update and validate the extent map to return
   */
  STATIC void
  xfs_bmapi_update_map(
  	struct xfs_bmbt_irec	**map,
  	xfs_fileoff_t		*bno,
  	xfs_filblks_t		*len,
  	xfs_fileoff_t		obno,
  	xfs_fileoff_t		end,
  	int			*n,
  	int			flags)
  {
  	xfs_bmbt_irec_t	*mval = *map;
  
  	ASSERT((flags & XFS_BMAPI_ENTIRE) ||
  	       ((mval->br_startoff + mval->br_blockcount) <= end));
  	ASSERT((flags & XFS_BMAPI_ENTIRE) || (mval->br_blockcount <= *len) ||
  	       (mval->br_startoff < obno));
  
  	*bno = mval->br_startoff + mval->br_blockcount;
  	*len = end - *bno;
  	if (*n > 0 && mval->br_startoff == mval[-1].br_startoff) {
  		/* update previous map with new information */
  		ASSERT(mval->br_startblock == mval[-1].br_startblock);
  		ASSERT(mval->br_blockcount > mval[-1].br_blockcount);
  		ASSERT(mval->br_state == mval[-1].br_state);
  		mval[-1].br_blockcount = mval->br_blockcount;
  		mval[-1].br_state = mval->br_state;
  	} else if (*n > 0 && mval->br_startblock != DELAYSTARTBLOCK &&
  		   mval[-1].br_startblock != DELAYSTARTBLOCK &&
  		   mval[-1].br_startblock != HOLESTARTBLOCK &&
  		   mval->br_startblock == mval[-1].br_startblock +
  					  mval[-1].br_blockcount &&
  		   mval[-1].br_state == mval->br_state) {
  		ASSERT(mval->br_startoff ==
  		       mval[-1].br_startoff + mval[-1].br_blockcount);
  		mval[-1].br_blockcount += mval->br_blockcount;
  	} else if (*n > 0 &&
  		   mval->br_startblock == DELAYSTARTBLOCK &&
  		   mval[-1].br_startblock == DELAYSTARTBLOCK &&
  		   mval->br_startoff ==
  		   mval[-1].br_startoff + mval[-1].br_blockcount) {
  		mval[-1].br_blockcount += mval->br_blockcount;
  		mval[-1].br_state = mval->br_state;
  	} else if (!((*n == 0) &&
  		     ((mval->br_startoff + mval->br_blockcount) <=
  		      obno))) {
  		mval++;
  		(*n)++;
  	}
  	*map = mval;
  }
  
  /*
   * Map file blocks to filesystem blocks without allocation.
   */
  int
  xfs_bmapi_read(
  	struct xfs_inode	*ip,
  	xfs_fileoff_t		bno,
  	xfs_filblks_t		len,
  	struct xfs_bmbt_irec	*mval,
  	int			*nmap,
  	int			flags)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_ifork	*ifp;
  	struct xfs_bmbt_irec	got;
  	xfs_fileoff_t		obno;
  	xfs_fileoff_t		end;
  	struct xfs_iext_cursor	icur;
  	int			error;
  	bool			eof = false;
  	int			n = 0;
  	int			whichfork = xfs_bmapi_whichfork(flags);
  
  	ASSERT(*nmap >= 1);
  	ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK|XFS_BMAPI_ENTIRE|
  			   XFS_BMAPI_COWFORK)));
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED|XFS_ILOCK_EXCL));
  
  	if (unlikely(XFS_TEST_ERROR(
  	    (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
  	     XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
  	     mp, XFS_ERRTAG_BMAPIFORMAT))) {
  		XFS_ERROR_REPORT("xfs_bmapi_read", XFS_ERRLEVEL_LOW, mp);
  		return -EFSCORRUPTED;
  	}
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	XFS_STATS_INC(mp, xs_blk_mapr);
  
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  
  	/* No CoW fork?  Return a hole. */
  	if (whichfork == XFS_COW_FORK && !ifp) {
  		mval->br_startoff = bno;
  		mval->br_startblock = HOLESTARTBLOCK;
  		mval->br_blockcount = len;
  		mval->br_state = XFS_EXT_NORM;
  		*nmap = 1;
  		return 0;
  	}
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(NULL, ip, whichfork);
  		if (error)
  			return error;
  	}
  
  	if (!xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got))
  		eof = true;
  	end = bno + len;
  	obno = bno;
  
  	while (bno < end && n < *nmap) {
  		/* Reading past eof, act as though there's a hole up to end. */
  		if (eof)
  			got.br_startoff = end;
  		if (got.br_startoff > bno) {
  			/* Reading in a hole.  */
  			mval->br_startoff = bno;
  			mval->br_startblock = HOLESTARTBLOCK;
  			mval->br_blockcount =
  				XFS_FILBLKS_MIN(len, got.br_startoff - bno);
  			mval->br_state = XFS_EXT_NORM;
  			bno += mval->br_blockcount;
  			len -= mval->br_blockcount;
  			mval++;
  			n++;
  			continue;
  		}
  
  		/* set up the extent map to return. */
  		xfs_bmapi_trim_map(mval, &got, &bno, len, obno, end, n, flags);
  		xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);
  
  		/* If we're done, stop now. */
  		if (bno >= end || n >= *nmap)
  			break;
  
  		/* Else go on to the next record. */
  		if (!xfs_iext_next_extent(ifp, &icur, &got))
  			eof = true;
  	}
  	*nmap = n;
  	return 0;
  }
  
  /*
   * Add a delayed allocation extent to an inode. Blocks are reserved from the
   * global pool and the extent inserted into the inode in-core extent tree.
   *
   * On entry, got refers to the first extent beyond the offset of the extent to
   * allocate or eof is specified if no such extent exists. On return, got refers
   * to the extent record that was inserted to the inode fork.
   *
   * Note that the allocated extent may have been merged with contiguous extents
   * during insertion into the inode fork. Thus, got does not reflect the current
   * state of the inode fork on return. If necessary, the caller can use lastx to
   * look up the updated record in the inode fork.
   */
  int
  xfs_bmapi_reserve_delalloc(
  	struct xfs_inode	*ip,
  	int			whichfork,
  	xfs_fileoff_t		off,
  	xfs_filblks_t		len,
  	xfs_filblks_t		prealloc,
  	struct xfs_bmbt_irec	*got,
  	struct xfs_iext_cursor	*icur,
  	int			eof)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	xfs_extlen_t		alen;
  	xfs_extlen_t		indlen;
  	int			error;
  	xfs_fileoff_t		aoff = off;
  
  	/*
  	 * Cap the alloc length. Keep track of prealloc so we know whether to
  	 * tag the inode before we return.
  	 */
  	alen = XFS_FILBLKS_MIN(len + prealloc, MAXEXTLEN);
  	if (!eof)
  		alen = XFS_FILBLKS_MIN(alen, got->br_startoff - aoff);
  	if (prealloc && alen >= len)
  		prealloc = alen - len;
  
  	/* Figure out the extent size, adjust alen */
  	if (whichfork == XFS_COW_FORK) {
  		struct xfs_bmbt_irec	prev;
  		xfs_extlen_t		extsz = xfs_get_cowextsz_hint(ip);
  
  		if (!xfs_iext_peek_prev_extent(ifp, icur, &prev))
  			prev.br_startoff = NULLFILEOFF;
  
  		error = xfs_bmap_extsize_align(mp, got, &prev, extsz, 0, eof,
  					       1, 0, &aoff, &alen);
  		ASSERT(!error);
  	}
  
  	/*
  	 * Make a transaction-less quota reservation for delayed allocation
  	 * blocks.  This number gets adjusted later.  We return if we haven't
  	 * allocated blocks already inside this loop.
  	 */
  	error = xfs_trans_reserve_quota_nblks(NULL, ip, (long)alen, 0,
  						XFS_QMOPT_RES_REGBLKS);
  	if (error)
  		return error;
  
  	/*
  	 * Split changing sb for alen and indlen since they could be coming
  	 * from different places.
  	 */
  	indlen = (xfs_extlen_t)xfs_bmap_worst_indlen(ip, alen);
  	ASSERT(indlen > 0);
  
  	error = xfs_mod_fdblocks(mp, -((int64_t)alen), false);
  	if (error)
  		goto out_unreserve_quota;
  
  	error = xfs_mod_fdblocks(mp, -((int64_t)indlen), false);
  	if (error)
  		goto out_unreserve_blocks;
  
  
  	ip->i_delayed_blks += alen;
  	xfs_mod_delalloc(ip->i_mount, alen + indlen);
  
  	got->br_startoff = aoff;
  	got->br_startblock = nullstartblock(indlen);
  	got->br_blockcount = alen;
  	got->br_state = XFS_EXT_NORM;
  
  	xfs_bmap_add_extent_hole_delay(ip, whichfork, icur, got);
  
  	/*
  	 * Tag the inode if blocks were preallocated. Note that COW fork
  	 * preallocation can occur at the start or end of the extent, even when
  	 * prealloc == 0, so we must also check the aligned offset and length.
  	 */
  	if (whichfork == XFS_DATA_FORK && prealloc)
  		xfs_inode_set_eofblocks_tag(ip);
  	if (whichfork == XFS_COW_FORK && (prealloc || aoff < off || alen > len))
  		xfs_inode_set_cowblocks_tag(ip);
  
  	return 0;
  
  out_unreserve_blocks:
  	xfs_mod_fdblocks(mp, alen, false);
  out_unreserve_quota:
  	if (XFS_IS_QUOTA_ON(mp))
  		xfs_trans_unreserve_quota_nblks(NULL, ip, (long)alen, 0,
  						XFS_QMOPT_RES_REGBLKS);
  	return error;
  }
  
  static int
  xfs_bmapi_allocate(
  	struct xfs_bmalloca	*bma)
  {
  	struct xfs_mount	*mp = bma->ip->i_mount;
  	int			whichfork = xfs_bmapi_whichfork(bma->flags);
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(bma->ip, whichfork);
  	int			tmp_logflags = 0;
  	int			error;
  
  	ASSERT(bma->length > 0);
  
  	/*
  	 * For the wasdelay case, we could also just allocate the stuff asked
  	 * for in this bmap call but that wouldn't be as good.
  	 */
  	if (bma->wasdel) {
  		bma->length = (xfs_extlen_t)bma->got.br_blockcount;
  		bma->offset = bma->got.br_startoff;
  		xfs_iext_peek_prev_extent(ifp, &bma->icur, &bma->prev);
  	} else {
  		bma->length = XFS_FILBLKS_MIN(bma->length, MAXEXTLEN);
  		if (!bma->eof)
  			bma->length = XFS_FILBLKS_MIN(bma->length,
  					bma->got.br_startoff - bma->offset);
  	}
  
  	/*
  	 * Set the data type being allocated. For the data fork, the first data
  	 * in the file is treated differently to all other allocations. For the
  	 * attribute fork, we only need to ensure the allocated range is not on
  	 * the busy list.
  	 */
  	if (!(bma->flags & XFS_BMAPI_METADATA)) {
  		bma->datatype = XFS_ALLOC_NOBUSY;
  		if (whichfork == XFS_DATA_FORK) {
  			if (bma->offset == 0)
  				bma->datatype |= XFS_ALLOC_INITIAL_USER_DATA;
  			else
  				bma->datatype |= XFS_ALLOC_USERDATA;
  		}
  		if (bma->flags & XFS_BMAPI_ZERO)
  			bma->datatype |= XFS_ALLOC_USERDATA_ZERO;
  	}
  
  	bma->minlen = (bma->flags & XFS_BMAPI_CONTIG) ? bma->length : 1;
  
  	/*
  	 * Only want to do the alignment at the eof if it is userdata and
  	 * allocation length is larger than a stripe unit.
  	 */
  	if (mp->m_dalign && bma->length >= mp->m_dalign &&
  	    !(bma->flags & XFS_BMAPI_METADATA) && whichfork == XFS_DATA_FORK) {
  		error = xfs_bmap_isaeof(bma, whichfork);
  		if (error)
  			return error;
  	}
  
  	error = xfs_bmap_alloc(bma);
  	if (error)
  		return error;
  
  	if (bma->blkno == NULLFSBLOCK)
  		return 0;
  	if ((ifp->if_flags & XFS_IFBROOT) && !bma->cur)
  		bma->cur = xfs_bmbt_init_cursor(mp, bma->tp, bma->ip, whichfork);
  	/*
  	 * Bump the number of extents we've allocated
  	 * in this call.
  	 */
  	bma->nallocs++;
  
  	if (bma->cur)
  		bma->cur->bc_private.b.flags =
  			bma->wasdel ? XFS_BTCUR_BPRV_WASDEL : 0;
  
  	bma->got.br_startoff = bma->offset;
  	bma->got.br_startblock = bma->blkno;
  	bma->got.br_blockcount = bma->length;
  	bma->got.br_state = XFS_EXT_NORM;
  
  	/*
  	 * In the data fork, a wasdelay extent has been initialized, so
  	 * shouldn't be flagged as unwritten.
  	 *
  	 * For the cow fork, however, we convert delalloc reservations
  	 * (extents allocated for speculative preallocation) to
  	 * allocated unwritten extents, and only convert the unwritten
  	 * extents to real extents when we're about to write the data.
  	 */
  	if ((!bma->wasdel || (bma->flags & XFS_BMAPI_COWFORK)) &&
  	    (bma->flags & XFS_BMAPI_PREALLOC))
  		bma->got.br_state = XFS_EXT_UNWRITTEN;
  
  	if (bma->wasdel)
  		error = xfs_bmap_add_extent_delay_real(bma, whichfork);
  	else
  		error = xfs_bmap_add_extent_hole_real(bma->tp, bma->ip,
  				whichfork, &bma->icur, &bma->cur, &bma->got,
  				&bma->logflags, bma->flags);
  
  	bma->logflags |= tmp_logflags;
  	if (error)
  		return error;
  
  	/*
  	 * Update our extent pointer, given that xfs_bmap_add_extent_delay_real
  	 * or xfs_bmap_add_extent_hole_real might have merged it into one of
  	 * the neighbouring ones.
  	 */
  	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
  
  	ASSERT(bma->got.br_startoff <= bma->offset);
  	ASSERT(bma->got.br_startoff + bma->got.br_blockcount >=
  	       bma->offset + bma->length);
  	ASSERT(bma->got.br_state == XFS_EXT_NORM ||
  	       bma->got.br_state == XFS_EXT_UNWRITTEN);
  	return 0;
  }
  
  STATIC int
  xfs_bmapi_convert_unwritten(
  	struct xfs_bmalloca	*bma,
  	struct xfs_bmbt_irec	*mval,
  	xfs_filblks_t		len,
  	int			flags)
  {
  	int			whichfork = xfs_bmapi_whichfork(flags);
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(bma->ip, whichfork);
  	int			tmp_logflags = 0;
  	int			error;
  
  	/* check if we need to do unwritten->real conversion */
  	if (mval->br_state == XFS_EXT_UNWRITTEN &&
  	    (flags & XFS_BMAPI_PREALLOC))
  		return 0;
  
  	/* check if we need to do real->unwritten conversion */
  	if (mval->br_state == XFS_EXT_NORM &&
  	    (flags & (XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT)) !=
  			(XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT))
  		return 0;
  
  	/*
  	 * Modify (by adding) the state flag, if writing.
  	 */
  	ASSERT(mval->br_blockcount <= len);
  	if ((ifp->if_flags & XFS_IFBROOT) && !bma->cur) {
  		bma->cur = xfs_bmbt_init_cursor(bma->ip->i_mount, bma->tp,
  					bma->ip, whichfork);
  	}
  	mval->br_state = (mval->br_state == XFS_EXT_UNWRITTEN)
  				? XFS_EXT_NORM : XFS_EXT_UNWRITTEN;
  
  	/*
  	 * Before insertion into the bmbt, zero the range being converted
  	 * if required.
  	 */
  	if (flags & XFS_BMAPI_ZERO) {
  		error = xfs_zero_extent(bma->ip, mval->br_startblock,
  					mval->br_blockcount);
  		if (error)
  			return error;
  	}
  
  	error = xfs_bmap_add_extent_unwritten_real(bma->tp, bma->ip, whichfork,
  			&bma->icur, &bma->cur, mval, &tmp_logflags);
  	/*
  	 * Log the inode core unconditionally in the unwritten extent conversion
  	 * path because the conversion might not have done so (e.g., if the
  	 * extent count hasn't changed). We need to make sure the inode is dirty
  	 * in the transaction for the sake of fsync(), even if nothing has
  	 * changed, because fsync() will not force the log for this transaction
  	 * unless it sees the inode pinned.
  	 *
  	 * Note: If we're only converting cow fork extents, there aren't
  	 * any on-disk updates to make, so we don't need to log anything.
  	 */
  	if (whichfork != XFS_COW_FORK)
  		bma->logflags |= tmp_logflags | XFS_ILOG_CORE;
  	if (error)
  		return error;
  
  	/*
  	 * Update our extent pointer, given that
  	 * xfs_bmap_add_extent_unwritten_real might have merged it into one
  	 * of the neighbouring ones.
  	 */
  	xfs_iext_get_extent(ifp, &bma->icur, &bma->got);
  
  	/*
  	 * We may have combined previously unwritten space with written space,
  	 * so generate another request.
  	 */
  	if (mval->br_blockcount < len)
  		return -EAGAIN;
  	return 0;
  }
  
  static inline xfs_extlen_t
  xfs_bmapi_minleft(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	int			fork)
  {
  	if (tp && tp->t_firstblock != NULLFSBLOCK)
  		return 0;
  	if (XFS_IFORK_FORMAT(ip, fork) != XFS_DINODE_FMT_BTREE)
  		return 1;
  	return be16_to_cpu(XFS_IFORK_PTR(ip, fork)->if_broot->bb_level) + 1;
  }
  
  /*
   * Log whatever the flags say, even if error.  Otherwise we might miss detecting
   * a case where the data is changed, there's an error, and it's not logged so we
   * don't shutdown when we should.  Don't bother logging extents/btree changes if
   * we converted to the other format.
   */
  static void
  xfs_bmapi_finish(
  	struct xfs_bmalloca	*bma,
  	int			whichfork,
  	int			error)
  {
  	if ((bma->logflags & xfs_ilog_fext(whichfork)) &&
  	    XFS_IFORK_FORMAT(bma->ip, whichfork) != XFS_DINODE_FMT_EXTENTS)
  		bma->logflags &= ~xfs_ilog_fext(whichfork);
  	else if ((bma->logflags & xfs_ilog_fbroot(whichfork)) &&
  		 XFS_IFORK_FORMAT(bma->ip, whichfork) != XFS_DINODE_FMT_BTREE)
  		bma->logflags &= ~xfs_ilog_fbroot(whichfork);
  
  	if (bma->logflags)
  		xfs_trans_log_inode(bma->tp, bma->ip, bma->logflags);
  	if (bma->cur)
  		xfs_btree_del_cursor(bma->cur, error);
  }
  
  /*
   * Map file blocks to filesystem blocks, and allocate blocks or convert the
   * extent state if necessary.  Details behaviour is controlled by the flags
   * parameter.  Only allocates blocks from a single allocation group, to avoid
   * locking problems.
   */
  int
  xfs_bmapi_write(
  	struct xfs_trans	*tp,		/* transaction pointer */
  	struct xfs_inode	*ip,		/* incore inode */
  	xfs_fileoff_t		bno,		/* starting file offs. mapped */
  	xfs_filblks_t		len,		/* length to map in file */
  	int			flags,		/* XFS_BMAPI_... */
  	xfs_extlen_t		total,		/* total blocks needed */
  	struct xfs_bmbt_irec	*mval,		/* output: map values */
  	int			*nmap)		/* i/o: mval size/count */
  {
  	struct xfs_bmalloca	bma = {
  		.tp		= tp,
  		.ip		= ip,
  		.total		= total,
  	};
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_ifork	*ifp;
  	xfs_fileoff_t		end;		/* end of mapped file region */
  	bool			eof = false;	/* after the end of extents */
  	int			error;		/* error return */
  	int			n;		/* current extent index */
  	xfs_fileoff_t		obno;		/* old block number (offset) */
  	int			whichfork;	/* data or attr fork */
  
  #ifdef DEBUG
  	xfs_fileoff_t		orig_bno;	/* original block number value */
  	int			orig_flags;	/* original flags arg value */
  	xfs_filblks_t		orig_len;	/* original value of len arg */
  	struct xfs_bmbt_irec	*orig_mval;	/* original value of mval */
  	int			orig_nmap;	/* original value of *nmap */
  
  	orig_bno = bno;
  	orig_len = len;
  	orig_flags = flags;
  	orig_mval = mval;
  	orig_nmap = *nmap;
  #endif
  	whichfork = xfs_bmapi_whichfork(flags);
  
  	ASSERT(*nmap >= 1);
  	ASSERT(*nmap <= XFS_BMAP_MAX_NMAP);
  	ASSERT(tp != NULL);
  	ASSERT(len > 0);
  	ASSERT(XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_LOCAL);
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(!(flags & XFS_BMAPI_REMAP));
  
  	/* zeroing is for currently only for data extents, not metadata */
  	ASSERT((flags & (XFS_BMAPI_METADATA | XFS_BMAPI_ZERO)) !=
  			(XFS_BMAPI_METADATA | XFS_BMAPI_ZERO));
  	/*
  	 * we can allocate unwritten extents or pre-zero allocated blocks,
  	 * but it makes no sense to do both at once. This would result in
  	 * zeroing the unwritten extent twice, but it still being an
  	 * unwritten extent....
  	 */
  	ASSERT((flags & (XFS_BMAPI_PREALLOC | XFS_BMAPI_ZERO)) !=
  			(XFS_BMAPI_PREALLOC | XFS_BMAPI_ZERO));
  
  	if (unlikely(XFS_TEST_ERROR(
  	    (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
  	     XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
  	     mp, XFS_ERRTAG_BMAPIFORMAT))) {
  		XFS_ERROR_REPORT("xfs_bmapi_write", XFS_ERRLEVEL_LOW, mp);
  		return -EFSCORRUPTED;
  	}
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  
  	XFS_STATS_INC(mp, xs_blk_mapw);
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(tp, ip, whichfork);
  		if (error)
  			goto error0;
  	}
  
  	if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.icur, &bma.got))
  		eof = true;
  	if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
  		bma.prev.br_startoff = NULLFILEOFF;
  	bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork);
  
  	n = 0;
  	end = bno + len;
  	obno = bno;
  	while (bno < end && n < *nmap) {
  		bool			need_alloc = false, wasdelay = false;
  
  		/* in hole or beyond EOF? */
  		if (eof || bma.got.br_startoff > bno) {
  			/*
  			 * CoW fork conversions should /never/ hit EOF or
  			 * holes.  There should always be something for us
  			 * to work on.
  			 */
  			ASSERT(!((flags & XFS_BMAPI_CONVERT) &&
  			         (flags & XFS_BMAPI_COWFORK)));
  
  			need_alloc = true;
  		} else if (isnullstartblock(bma.got.br_startblock)) {
  			wasdelay = true;
  		}
  
  		/*
  		 * First, deal with the hole before the allocated space
  		 * that we found, if any.
  		 */
  		if (need_alloc || wasdelay) {
  			bma.eof = eof;
  			bma.conv = !!(flags & XFS_BMAPI_CONVERT);
  			bma.wasdel = wasdelay;
  			bma.offset = bno;
  			bma.flags = flags;
  
  			/*
  			 * There's a 32/64 bit type mismatch between the
  			 * allocation length request (which can be 64 bits in
  			 * length) and the bma length request, which is
  			 * xfs_extlen_t and therefore 32 bits. Hence we have to
  			 * check for 32-bit overflows and handle them here.
  			 */
  			if (len > (xfs_filblks_t)MAXEXTLEN)
  				bma.length = MAXEXTLEN;
  			else
  				bma.length = len;
  
  			ASSERT(len > 0);
  			ASSERT(bma.length > 0);
  			error = xfs_bmapi_allocate(&bma);
  			if (error)
  				goto error0;
  			if (bma.blkno == NULLFSBLOCK)
  				break;
  
  			/*
  			 * If this is a CoW allocation, record the data in
  			 * the refcount btree for orphan recovery.
  			 */
  			if (whichfork == XFS_COW_FORK) {
  				error = xfs_refcount_alloc_cow_extent(tp,
  						bma.blkno, bma.length);
  				if (error)
  					goto error0;
  			}
  		}
  
  		/* Deal with the allocated space we found.  */
  		xfs_bmapi_trim_map(mval, &bma.got, &bno, len, obno,
  							end, n, flags);
  
  		/* Execute unwritten extent conversion if necessary */
  		error = xfs_bmapi_convert_unwritten(&bma, mval, len, flags);
  		if (error == -EAGAIN)
  			continue;
  		if (error)
  			goto error0;
  
  		/* update the extent map to return */
  		xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);
  
  		/*
  		 * If we're done, stop now.  Stop when we've allocated
  		 * XFS_BMAP_MAX_NMAP extents no matter what.  Otherwise
  		 * the transaction may get too big.
  		 */
  		if (bno >= end || n >= *nmap || bma.nallocs >= *nmap)
  			break;
  
  		/* Else go on to the next record. */
  		bma.prev = bma.got;
  		if (!xfs_iext_next_extent(ifp, &bma.icur, &bma.got))
  			eof = true;
  	}
  	*nmap = n;
  
  	error = xfs_bmap_btree_to_extents(tp, ip, bma.cur, &bma.logflags,
  			whichfork);
  	if (error)
  		goto error0;
  
  	ASSERT(XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE ||
  	       XFS_IFORK_NEXTENTS(ip, whichfork) >
  		XFS_IFORK_MAXEXT(ip, whichfork));
  	xfs_bmapi_finish(&bma, whichfork, 0);
  	xfs_bmap_validate_ret(orig_bno, orig_len, orig_flags, orig_mval,
  		orig_nmap, *nmap);
  	return 0;
  error0:
  	xfs_bmapi_finish(&bma, whichfork, error);
  	return error;
  }
  
  /*
   * Convert an existing delalloc extent to real blocks based on file offset. This
   * attempts to allocate the entire delalloc extent and may require multiple
   * invocations to allocate the target offset if a large enough physical extent
   * is not available.
   */
  int
  xfs_bmapi_convert_delalloc(
  	struct xfs_inode	*ip,
  	int			whichfork,
  	xfs_fileoff_t		offset_fsb,
  	struct xfs_bmbt_irec	*imap,
  	unsigned int		*seq)
  {
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_bmalloca	bma = { NULL };
  	struct xfs_trans	*tp;
  	int			error;
  
  	/*
  	 * Space for the extent and indirect blocks was reserved when the
  	 * delalloc extent was created so there's no need to do so here.
  	 */
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0,
  				XFS_TRANS_RESERVE, &tp);
  	if (error)
  		return error;
  
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, 0);
  
  	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &bma.icur, &bma.got) ||
  	    bma.got.br_startoff > offset_fsb) {
  		/*
  		 * No extent found in the range we are trying to convert.  This
  		 * should only happen for the COW fork, where another thread
  		 * might have moved the extent to the data fork in the meantime.
  		 */
  		WARN_ON_ONCE(whichfork != XFS_COW_FORK);
  		error = -EAGAIN;
  		goto out_trans_cancel;
  	}
  
  	/*
  	 * If we find a real extent here we raced with another thread converting
  	 * the extent.  Just return the real extent at this offset.
  	 */
  	if (!isnullstartblock(bma.got.br_startblock)) {
  		*imap = bma.got;
  		*seq = READ_ONCE(ifp->if_seq);
  		goto out_trans_cancel;
  	}
  
  	bma.tp = tp;
  	bma.ip = ip;
  	bma.wasdel = true;
  	bma.offset = bma.got.br_startoff;
  	bma.length = max_t(xfs_filblks_t, bma.got.br_blockcount, MAXEXTLEN);
  	bma.total = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
  	bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork);
  	if (whichfork == XFS_COW_FORK)
  		bma.flags = XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC;
  
  	if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
  		bma.prev.br_startoff = NULLFILEOFF;
  
  	error = xfs_bmapi_allocate(&bma);
  	if (error)
  		goto out_finish;
  
  	error = -ENOSPC;
  	if (WARN_ON_ONCE(bma.blkno == NULLFSBLOCK))
  		goto out_finish;
  	error = -EFSCORRUPTED;
  	if (WARN_ON_ONCE(!bma.got.br_startblock && !XFS_IS_REALTIME_INODE(ip)))
  		goto out_finish;
  
  	XFS_STATS_ADD(mp, xs_xstrat_bytes, XFS_FSB_TO_B(mp, bma.length));
  	XFS_STATS_INC(mp, xs_xstrat_quick);
  
  	ASSERT(!isnullstartblock(bma.got.br_startblock));
  	*imap = bma.got;
  	*seq = READ_ONCE(ifp->if_seq);
  
  	if (whichfork == XFS_COW_FORK) {
  		error = xfs_refcount_alloc_cow_extent(tp, bma.blkno,
  				bma.length);
  		if (error)
  			goto out_finish;
  	}
  
  	error = xfs_bmap_btree_to_extents(tp, ip, bma.cur, &bma.logflags,
  			whichfork);
  	if (error)
  		goto out_finish;
  
  	xfs_bmapi_finish(&bma, whichfork, 0);
  	error = xfs_trans_commit(tp);
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return error;
  
  out_finish:
  	xfs_bmapi_finish(&bma, whichfork, error);
  out_trans_cancel:
  	xfs_trans_cancel(tp);
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return error;
  }
  
  int
  xfs_bmapi_remap(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	xfs_fileoff_t		bno,
  	xfs_filblks_t		len,
  	xfs_fsblock_t		startblock,
  	int			flags)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_ifork	*ifp;
  	struct xfs_btree_cur	*cur = NULL;
  	struct xfs_bmbt_irec	got;
  	struct xfs_iext_cursor	icur;
  	int			whichfork = xfs_bmapi_whichfork(flags);
  	int			logflags = 0, error;
  
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	ASSERT(len > 0);
  	ASSERT(len <= (xfs_filblks_t)MAXEXTLEN);
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC |
  			   XFS_BMAPI_NORMAP)));
  	ASSERT((flags & (XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC)) !=
  			(XFS_BMAPI_ATTRFORK | XFS_BMAPI_PREALLOC));
  
  	if (unlikely(XFS_TEST_ERROR(
  	    (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
  	     XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
  	     mp, XFS_ERRTAG_BMAPIFORMAT))) {
  		XFS_ERROR_REPORT("xfs_bmapi_remap", XFS_ERRLEVEL_LOW, mp);
  		return -EFSCORRUPTED;
  	}
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(tp, ip, whichfork);
  		if (error)
  			return error;
  	}
  
  	if (xfs_iext_lookup_extent(ip, ifp, bno, &icur, &got)) {
  		/* make sure we only reflink into a hole. */
  		ASSERT(got.br_startoff > bno);
  		ASSERT(got.br_startoff - bno >= len);
  	}
  
  	ip->i_d.di_nblocks += len;
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	if (ifp->if_flags & XFS_IFBROOT) {
  		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
  		cur->bc_private.b.flags = 0;
  	}
  
  	got.br_startoff = bno;
  	got.br_startblock = startblock;
  	got.br_blockcount = len;
  	if (flags & XFS_BMAPI_PREALLOC)
  		got.br_state = XFS_EXT_UNWRITTEN;
  	else
  		got.br_state = XFS_EXT_NORM;
  
  	error = xfs_bmap_add_extent_hole_real(tp, ip, whichfork, &icur,
  			&cur, &got, &logflags, flags);
  	if (error)
  		goto error0;
  
  	error = xfs_bmap_btree_to_extents(tp, ip, cur, &logflags, whichfork);
  
  error0:
  	if (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS)
  		logflags &= ~XFS_ILOG_DEXT;
  	else if (ip->i_d.di_format != XFS_DINODE_FMT_BTREE)
  		logflags &= ~XFS_ILOG_DBROOT;
  
  	if (logflags)
  		xfs_trans_log_inode(tp, ip, logflags);
  	if (cur)
  		xfs_btree_del_cursor(cur, error);
  	return error;
  }
  
  /*
   * When a delalloc extent is split (e.g., due to a hole punch), the original
   * indlen reservation must be shared across the two new extents that are left
   * behind.
   *
   * Given the original reservation and the worst case indlen for the two new
   * extents (as calculated by xfs_bmap_worst_indlen()), split the original
   * reservation fairly across the two new extents. If necessary, steal available
   * blocks from a deleted extent to make up a reservation deficiency (e.g., if
   * ores == 1). The number of stolen blocks is returned. The availability and
   * subsequent accounting of stolen blocks is the responsibility of the caller.
   */
  static xfs_filblks_t
  xfs_bmap_split_indlen(
  	xfs_filblks_t			ores,		/* original res. */
  	xfs_filblks_t			*indlen1,	/* ext1 worst indlen */
  	xfs_filblks_t			*indlen2,	/* ext2 worst indlen */
  	xfs_filblks_t			avail)		/* stealable blocks */
  {
  	xfs_filblks_t			len1 = *indlen1;
  	xfs_filblks_t			len2 = *indlen2;
  	xfs_filblks_t			nres = len1 + len2; /* new total res. */
  	xfs_filblks_t			stolen = 0;
  	xfs_filblks_t			resfactor;
  
  	/*
  	 * Steal as many blocks as we can to try and satisfy the worst case
  	 * indlen for both new extents.
  	 */
  	if (ores < nres && avail)
  		stolen = XFS_FILBLKS_MIN(nres - ores, avail);
  	ores += stolen;
  
  	 /* nothing else to do if we've satisfied the new reservation */
  	if (ores >= nres)
  		return stolen;
  
  	/*
  	 * We can't meet the total required reservation for the two extents.
  	 * Calculate the percent of the overall shortage between both extents
  	 * and apply this percentage to each of the requested indlen values.
  	 * This distributes the shortage fairly and reduces the chances that one
  	 * of the two extents is left with nothing when extents are repeatedly
  	 * split.
  	 */
  	resfactor = (ores * 100);
  	do_div(resfactor, nres);
  	len1 *= resfactor;
  	do_div(len1, 100);
  	len2 *= resfactor;
  	do_div(len2, 100);
  	ASSERT(len1 + len2 <= ores);
  	ASSERT(len1 < *indlen1 && len2 < *indlen2);
  
  	/*
  	 * Hand out the remainder to each extent. If one of the two reservations
  	 * is zero, we want to make sure that one gets a block first. The loop
  	 * below starts with len1, so hand len2 a block right off the bat if it
  	 * is zero.
  	 */
  	ores -= (len1 + len2);
  	ASSERT((*indlen1 - len1) + (*indlen2 - len2) >= ores);
  	if (ores && !len2 && *indlen2) {
  		len2++;
  		ores--;
  	}
  	while (ores) {
  		if (len1 < *indlen1) {
  			len1++;
  			ores--;
  		}
  		if (!ores)
  			break;
  		if (len2 < *indlen2) {
  			len2++;
  			ores--;
  		}
  	}
  
  	*indlen1 = len1;
  	*indlen2 = len2;
  
  	return stolen;
  }
  
  int
  xfs_bmap_del_extent_delay(
  	struct xfs_inode	*ip,
  	int			whichfork,
  	struct xfs_iext_cursor	*icur,
  	struct xfs_bmbt_irec	*got,
  	struct xfs_bmbt_irec	*del)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_bmbt_irec	new;
  	int64_t			da_old, da_new, da_diff = 0;
  	xfs_fileoff_t		del_endoff, got_endoff;
  	xfs_filblks_t		got_indlen, new_indlen, stolen;
  	int			state = xfs_bmap_fork_to_state(whichfork);
  	int			error = 0;
  	bool			isrt;
  
  	XFS_STATS_INC(mp, xs_del_exlist);
  
  	isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
  	del_endoff = del->br_startoff + del->br_blockcount;
  	got_endoff = got->br_startoff + got->br_blockcount;
  	da_old = startblockval(got->br_startblock);
  	da_new = 0;
  
  	ASSERT(del->br_blockcount > 0);
  	ASSERT(got->br_startoff <= del->br_startoff);
  	ASSERT(got_endoff >= del_endoff);
  
  	if (isrt) {
  		uint64_t rtexts = XFS_FSB_TO_B(mp, del->br_blockcount);
  
  		do_div(rtexts, mp->m_sb.sb_rextsize);
  		xfs_mod_frextents(mp, rtexts);
  	}
  
  	/*
  	 * Update the inode delalloc counter now and wait to update the
  	 * sb counters as we might have to borrow some blocks for the
  	 * indirect block accounting.
  	 */
  	error = xfs_trans_reserve_quota_nblks(NULL, ip,
  			-((long)del->br_blockcount), 0,
  			isrt ? XFS_QMOPT_RES_RTBLKS : XFS_QMOPT_RES_REGBLKS);
  	if (error)
  		return error;
  	ip->i_delayed_blks -= del->br_blockcount;
  
  	if (got->br_startoff == del->br_startoff)
  		state |= BMAP_LEFT_FILLING;
  	if (got_endoff == del_endoff)
  		state |= BMAP_RIGHT_FILLING;
  
  	switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
  		/*
  		 * Matches the whole extent.  Delete the entry.
  		 */
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_prev(ifp, icur);
  		break;
  	case BMAP_LEFT_FILLING:
  		/*
  		 * Deleting the first part of the extent.
  		 */
  		got->br_startoff = del_endoff;
  		got->br_blockcount -= del->br_blockcount;
  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
  				got->br_blockcount), da_old);
  		got->br_startblock = nullstartblock((int)da_new);
  		xfs_iext_update_extent(ip, state, icur, got);
  		break;
  	case BMAP_RIGHT_FILLING:
  		/*
  		 * Deleting the last part of the extent.
  		 */
  		got->br_blockcount = got->br_blockcount - del->br_blockcount;
  		da_new = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip,
  				got->br_blockcount), da_old);
  		got->br_startblock = nullstartblock((int)da_new);
  		xfs_iext_update_extent(ip, state, icur, got);
  		break;
  	case 0:
  		/*
  		 * Deleting the middle of the extent.
  		 *
  		 * Distribute the original indlen reservation across the two new
  		 * extents.  Steal blocks from the deleted extent if necessary.
  		 * Stealing blocks simply fudges the fdblocks accounting below.
  		 * Warn if either of the new indlen reservations is zero as this
  		 * can lead to delalloc problems.
  		 */
  		got->br_blockcount = del->br_startoff - got->br_startoff;
  		got_indlen = xfs_bmap_worst_indlen(ip, got->br_blockcount);
  
  		new.br_blockcount = got_endoff - del_endoff;
  		new_indlen = xfs_bmap_worst_indlen(ip, new.br_blockcount);
  
  		WARN_ON_ONCE(!got_indlen || !new_indlen);
  		stolen = xfs_bmap_split_indlen(da_old, &got_indlen, &new_indlen,
  						       del->br_blockcount);
  
  		got->br_startblock = nullstartblock((int)got_indlen);
  
  		new.br_startoff = del_endoff;
  		new.br_state = got->br_state;
  		new.br_startblock = nullstartblock((int)new_indlen);
  
  		xfs_iext_update_extent(ip, state, icur, got);
  		xfs_iext_next(ifp, icur);
  		xfs_iext_insert(ip, icur, &new, state);
  
  		da_new = got_indlen + new_indlen - stolen;
  		del->br_blockcount -= stolen;
  		break;
  	}
  
  	ASSERT(da_old >= da_new);
  	da_diff = da_old - da_new;
  	if (!isrt)
  		da_diff += del->br_blockcount;
  	if (da_diff) {
  		xfs_mod_fdblocks(mp, da_diff, false);
  		xfs_mod_delalloc(mp, -da_diff);
  	}
  	return error;
  }
  
  void
  xfs_bmap_del_extent_cow(
  	struct xfs_inode	*ip,
  	struct xfs_iext_cursor	*icur,
  	struct xfs_bmbt_irec	*got,
  	struct xfs_bmbt_irec	*del)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
  	struct xfs_bmbt_irec	new;
  	xfs_fileoff_t		del_endoff, got_endoff;
  	int			state = BMAP_COWFORK;
  
  	XFS_STATS_INC(mp, xs_del_exlist);
  
  	del_endoff = del->br_startoff + del->br_blockcount;
  	got_endoff = got->br_startoff + got->br_blockcount;
  
  	ASSERT(del->br_blockcount > 0);
  	ASSERT(got->br_startoff <= del->br_startoff);
  	ASSERT(got_endoff >= del_endoff);
  	ASSERT(!isnullstartblock(got->br_startblock));
  
  	if (got->br_startoff == del->br_startoff)
  		state |= BMAP_LEFT_FILLING;
  	if (got_endoff == del_endoff)
  		state |= BMAP_RIGHT_FILLING;
  
  	switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
  		/*
  		 * Matches the whole extent.  Delete the entry.
  		 */
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_prev(ifp, icur);
  		break;
  	case BMAP_LEFT_FILLING:
  		/*
  		 * Deleting the first part of the extent.
  		 */
  		got->br_startoff = del_endoff;
  		got->br_blockcount -= del->br_blockcount;
  		got->br_startblock = del->br_startblock + del->br_blockcount;
  		xfs_iext_update_extent(ip, state, icur, got);
  		break;
  	case BMAP_RIGHT_FILLING:
  		/*
  		 * Deleting the last part of the extent.
  		 */
  		got->br_blockcount -= del->br_blockcount;
  		xfs_iext_update_extent(ip, state, icur, got);
  		break;
  	case 0:
  		/*
  		 * Deleting the middle of the extent.
  		 */
  		got->br_blockcount = del->br_startoff - got->br_startoff;
  
  		new.br_startoff = del_endoff;
  		new.br_blockcount = got_endoff - del_endoff;
  		new.br_state = got->br_state;
  		new.br_startblock = del->br_startblock + del->br_blockcount;
  
  		xfs_iext_update_extent(ip, state, icur, got);
  		xfs_iext_next(ifp, icur);
  		xfs_iext_insert(ip, icur, &new, state);
  		break;
  	}
  	ip->i_delayed_blks -= del->br_blockcount;
  }
  
  /*
   * Called by xfs_bmapi to update file extent records and the btree
   * after removing space.
   */
  STATIC int				/* error */
  xfs_bmap_del_extent_real(
  	xfs_inode_t		*ip,	/* incore inode pointer */
  	xfs_trans_t		*tp,	/* current transaction pointer */
  	struct xfs_iext_cursor	*icur,
  	xfs_btree_cur_t		*cur,	/* if null, not a btree */
  	xfs_bmbt_irec_t		*del,	/* data to remove from extents */
  	int			*logflagsp, /* inode logging flags */
  	int			whichfork, /* data or attr fork */
  	int			bflags)	/* bmapi flags */
  {
  	xfs_fsblock_t		del_endblock=0;	/* first block past del */
  	xfs_fileoff_t		del_endoff;	/* first offset past del */
  	int			do_fx;	/* free extent at end of routine */
  	int			error;	/* error return value */
  	int			flags = 0;/* inode logging flags */
  	struct xfs_bmbt_irec	got;	/* current extent entry */
  	xfs_fileoff_t		got_endoff;	/* first offset past got */
  	int			i;	/* temp state */
  	struct xfs_ifork	*ifp;	/* inode fork pointer */
  	xfs_mount_t		*mp;	/* mount structure */
  	xfs_filblks_t		nblks;	/* quota/sb block count */
  	xfs_bmbt_irec_t		new;	/* new record to be inserted */
  	/* REFERENCED */
  	uint			qfield;	/* quota field to update */
  	int			state = xfs_bmap_fork_to_state(whichfork);
  	struct xfs_bmbt_irec	old;
  
  	mp = ip->i_mount;
  	XFS_STATS_INC(mp, xs_del_exlist);
  
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	ASSERT(del->br_blockcount > 0);
  	xfs_iext_get_extent(ifp, icur, &got);
  	ASSERT(got.br_startoff <= del->br_startoff);
  	del_endoff = del->br_startoff + del->br_blockcount;
  	got_endoff = got.br_startoff + got.br_blockcount;
  	ASSERT(got_endoff >= del_endoff);
  	ASSERT(!isnullstartblock(got.br_startblock));
  	qfield = 0;
  	error = 0;
  
  	/*
  	 * If it's the case where the directory code is running with no block
  	 * reservation, and the deleted block is in the middle of its extent,
  	 * and the resulting insert of an extent would cause transformation to
  	 * btree format, then reject it.  The calling code will then swap blocks
  	 * around instead.  We have to do this now, rather than waiting for the
  	 * conversion to btree format, since the transaction will be dirty then.
  	 */
  	if (tp->t_blk_res == 0 &&
  	    XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_EXTENTS &&
  	    XFS_IFORK_NEXTENTS(ip, whichfork) >=
  			XFS_IFORK_MAXEXT(ip, whichfork) &&
  	    del->br_startoff > got.br_startoff && del_endoff < got_endoff)
  		return -ENOSPC;
  
  	flags = XFS_ILOG_CORE;
  	if (whichfork == XFS_DATA_FORK && XFS_IS_REALTIME_INODE(ip)) {
  		xfs_fsblock_t	bno;
  		xfs_filblks_t	len;
  		xfs_extlen_t	mod;
  
  		bno = div_u64_rem(del->br_startblock, mp->m_sb.sb_rextsize,
  				  &mod);
  		ASSERT(mod == 0);
  		len = div_u64_rem(del->br_blockcount, mp->m_sb.sb_rextsize,
  				  &mod);
  		ASSERT(mod == 0);
  
  		error = xfs_rtfree_extent(tp, bno, (xfs_extlen_t)len);
  		if (error)
  			goto done;
  		do_fx = 0;
  		nblks = len * mp->m_sb.sb_rextsize;
  		qfield = XFS_TRANS_DQ_RTBCOUNT;
  	} else {
  		do_fx = 1;
  		nblks = del->br_blockcount;
  		qfield = XFS_TRANS_DQ_BCOUNT;
  	}
  
  	del_endblock = del->br_startblock + del->br_blockcount;
  	if (cur) {
  		error = xfs_bmbt_lookup_eq(cur, &got, &i);
  		if (error)
  			goto done;
  		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  	}
  
  	if (got.br_startoff == del->br_startoff)
  		state |= BMAP_LEFT_FILLING;
  	if (got_endoff == del_endoff)
  		state |= BMAP_RIGHT_FILLING;
  
  	switch (state & (BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING)) {
  	case BMAP_LEFT_FILLING | BMAP_RIGHT_FILLING:
  		/*
  		 * Matches the whole extent.  Delete the entry.
  		 */
  		xfs_iext_remove(ip, icur, state);
  		xfs_iext_prev(ifp, icur);
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  			XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
  		flags |= XFS_ILOG_CORE;
  		if (!cur) {
  			flags |= xfs_ilog_fext(whichfork);
  			break;
  		}
  		if ((error = xfs_btree_delete(cur, &i)))
  			goto done;
  		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		break;
  	case BMAP_LEFT_FILLING:
  		/*
  		 * Deleting the first part of the extent.
  		 */
  		got.br_startoff = del_endoff;
  		got.br_startblock = del_endblock;
  		got.br_blockcount -= del->br_blockcount;
  		xfs_iext_update_extent(ip, state, icur, &got);
  		if (!cur) {
  			flags |= xfs_ilog_fext(whichfork);
  			break;
  		}
  		error = xfs_bmbt_update(cur, &got);
  		if (error)
  			goto done;
  		break;
  	case BMAP_RIGHT_FILLING:
  		/*
  		 * Deleting the last part of the extent.
  		 */
  		got.br_blockcount -= del->br_blockcount;
  		xfs_iext_update_extent(ip, state, icur, &got);
  		if (!cur) {
  			flags |= xfs_ilog_fext(whichfork);
  			break;
  		}
  		error = xfs_bmbt_update(cur, &got);
  		if (error)
  			goto done;
  		break;
  	case 0:
  		/*
  		 * Deleting the middle of the extent.
  		 */
  		old = got;
  
  		got.br_blockcount = del->br_startoff - got.br_startoff;
  		xfs_iext_update_extent(ip, state, icur, &got);
  
  		new.br_startoff = del_endoff;
  		new.br_blockcount = got_endoff - del_endoff;
  		new.br_state = got.br_state;
  		new.br_startblock = del_endblock;
  
  		flags |= XFS_ILOG_CORE;
  		if (cur) {
  			error = xfs_bmbt_update(cur, &got);
  			if (error)
  				goto done;
  			error = xfs_btree_increment(cur, 0, &i);
  			if (error)
  				goto done;
  			cur->bc_rec.b = new;
  			error = xfs_btree_insert(cur, &i);
  			if (error && error != -ENOSPC)
  				goto done;
  			/*
  			 * If get no-space back from btree insert, it tried a
  			 * split, and we have a zero block reservation.  Fix up
  			 * our state and return the error.
  			 */
  			if (error == -ENOSPC) {
  				/*
  				 * Reset the cursor, don't trust it after any
  				 * insert operation.
  				 */
  				error = xfs_bmbt_lookup_eq(cur, &got, &i);
  				if (error)
  					goto done;
  				XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  				/*
  				 * Update the btree record back
  				 * to the original value.
  				 */
  				error = xfs_bmbt_update(cur, &old);
  				if (error)
  					goto done;
  				/*
  				 * Reset the extent record back
  				 * to the original value.
  				 */
  				xfs_iext_update_extent(ip, state, icur, &old);
  				flags = 0;
  				error = -ENOSPC;
  				goto done;
  			}
  			XFS_WANT_CORRUPTED_GOTO(mp, i == 1, done);
  		} else
  			flags |= xfs_ilog_fext(whichfork);
  		XFS_IFORK_NEXT_SET(ip, whichfork,
  			XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
  		xfs_iext_next(ifp, icur);
  		xfs_iext_insert(ip, icur, &new, state);
  		break;
  	}
  
  	/* remove reverse mapping */
  	error = xfs_rmap_unmap_extent(tp, ip, whichfork, del);
  	if (error)
  		goto done;
  
  	/*
  	 * If we need to, add to list of extents to delete.
  	 */
  	if (do_fx && !(bflags & XFS_BMAPI_REMAP)) {
  		if (xfs_is_reflink_inode(ip) && whichfork == XFS_DATA_FORK) {
  			error = xfs_refcount_decrease_extent(tp, del);
  			if (error)
  				goto done;
  		} else {
  			__xfs_bmap_add_free(tp, del->br_startblock,
  					del->br_blockcount, NULL,
  					(bflags & XFS_BMAPI_NODISCARD) ||
  					del->br_state == XFS_EXT_UNWRITTEN);
  		}
  	}
  
  	/*
  	 * Adjust inode # blocks in the file.
  	 */
  	if (nblks)
  		ip->i_d.di_nblocks -= nblks;
  	/*
  	 * Adjust quota data.
  	 */
  	if (qfield && !(bflags & XFS_BMAPI_REMAP))
  		xfs_trans_mod_dquot_byino(tp, ip, qfield, (long)-nblks);
  
  done:
  	*logflagsp = flags;
  	return error;
  }
  
  /*
   * Unmap (remove) blocks from a file.
   * If nexts is nonzero then the number of extents to remove is limited to
   * that value.  If not all extents in the block range can be removed then
   * *done is set.
   */
  int						/* error */
  __xfs_bunmapi(
  	struct xfs_trans	*tp,		/* transaction pointer */
  	struct xfs_inode	*ip,		/* incore inode */
  	xfs_fileoff_t		start,		/* first file offset deleted */
  	xfs_filblks_t		*rlen,		/* i/o: amount remaining */
  	int			flags,		/* misc flags */
  	xfs_extnum_t		nexts)		/* number of extents max */
  {
  	struct xfs_btree_cur	*cur;		/* bmap btree cursor */
  	struct xfs_bmbt_irec	del;		/* extent being deleted */
  	int			error;		/* error return value */
  	xfs_extnum_t		extno;		/* extent number in list */
  	struct xfs_bmbt_irec	got;		/* current extent record */
  	struct xfs_ifork	*ifp;		/* inode fork pointer */
  	int			isrt;		/* freeing in rt area */
  	int			logflags;	/* transaction logging flags */
  	xfs_extlen_t		mod;		/* rt extent offset */
  	struct xfs_mount	*mp;		/* mount structure */
  	int			tmp_logflags;	/* partial logging flags */
  	int			wasdel;		/* was a delayed alloc extent */
  	int			whichfork;	/* data or attribute fork */
  	xfs_fsblock_t		sum;
  	xfs_filblks_t		len = *rlen;	/* length to unmap in file */
  	xfs_fileoff_t		max_len;
  	xfs_agnumber_t		prev_agno = NULLAGNUMBER, agno;
  	xfs_fileoff_t		end;
  	struct xfs_iext_cursor	icur;
  	bool			done = false;
  
  	trace_xfs_bunmap(ip, start, len, flags, _RET_IP_);
  
  	whichfork = xfs_bmapi_whichfork(flags);
  	ASSERT(whichfork != XFS_COW_FORK);
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	if (unlikely(
  	    XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
  	    XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE)) {
  		XFS_ERROR_REPORT("xfs_bunmapi", XFS_ERRLEVEL_LOW,
  				 ip->i_mount);
  		return -EFSCORRUPTED;
  	}
  	mp = ip->i_mount;
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(len > 0);
  	ASSERT(nexts >= 0);
  
  	/*
  	 * Guesstimate how many blocks we can unmap without running the risk of
  	 * blowing out the transaction with a mix of EFIs and reflink
  	 * adjustments.
  	 */
  	if (tp && xfs_is_reflink_inode(ip) && whichfork == XFS_DATA_FORK)
  		max_len = min(len, xfs_refcount_max_unmap(tp->t_log_res));
  	else
  		max_len = len;
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS) &&
  	    (error = xfs_iread_extents(tp, ip, whichfork)))
  		return error;
  	if (xfs_iext_count(ifp) == 0) {
  		*rlen = 0;
  		return 0;
  	}
  	XFS_STATS_INC(mp, xs_blk_unmap);
  	isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
  	end = start + len;
  
  	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &icur, &got)) {
  		*rlen = 0;
  		return 0;
  	}
  	end--;
  
  	logflags = 0;
  	if (ifp->if_flags & XFS_IFBROOT) {
  		ASSERT(XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_BTREE);
  		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
  		cur->bc_private.b.flags = 0;
  	} else
  		cur = NULL;
  
  	if (isrt) {
  		/*
  		 * Synchronize by locking the bitmap inode.
  		 */
  		xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL|XFS_ILOCK_RTBITMAP);
  		xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);
  		xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL|XFS_ILOCK_RTSUM);
  		xfs_trans_ijoin(tp, mp->m_rsumip, XFS_ILOCK_EXCL);
  	}
  
  	extno = 0;
  	while (end != (xfs_fileoff_t)-1 && end >= start &&
  	       (nexts == 0 || extno < nexts) && max_len > 0) {
  		/*
  		 * Is the found extent after a hole in which end lives?
  		 * Just back up to the previous extent, if so.
  		 */
  		if (got.br_startoff > end &&
  		    !xfs_iext_prev_extent(ifp, &icur, &got)) {
  			done = true;
  			break;
  		}
  		/*
  		 * Is the last block of this extent before the range
  		 * we're supposed to delete?  If so, we're done.
  		 */
  		end = XFS_FILEOFF_MIN(end,
  			got.br_startoff + got.br_blockcount - 1);
  		if (end < start)
  			break;
  		/*
  		 * Then deal with the (possibly delayed) allocated space
  		 * we found.
  		 */
  		del = got;
  		wasdel = isnullstartblock(del.br_startblock);
  
  		/*
  		 * Make sure we don't touch multiple AGF headers out of order
  		 * in a single transaction, as that could cause AB-BA deadlocks.
  		 */
  		if (!wasdel) {
  			agno = XFS_FSB_TO_AGNO(mp, del.br_startblock);
  			if (prev_agno != NULLAGNUMBER && prev_agno > agno)
  				break;
  			prev_agno = agno;
  		}
  		if (got.br_startoff < start) {
  			del.br_startoff = start;
  			del.br_blockcount -= start - got.br_startoff;
  			if (!wasdel)
  				del.br_startblock += start - got.br_startoff;
  		}
  		if (del.br_startoff + del.br_blockcount > end + 1)
  			del.br_blockcount = end + 1 - del.br_startoff;
  
  		/* How much can we safely unmap? */
  		if (max_len < del.br_blockcount) {
  			del.br_startoff += del.br_blockcount - max_len;
  			if (!wasdel)
  				del.br_startblock += del.br_blockcount - max_len;
  			del.br_blockcount = max_len;
  		}
  
  		if (!isrt)
  			goto delete;
  
  		sum = del.br_startblock + del.br_blockcount;
  		div_u64_rem(sum, mp->m_sb.sb_rextsize, &mod);
  		if (mod) {
  			/*
  			 * Realtime extent not lined up at the end.
  			 * The extent could have been split into written
  			 * and unwritten pieces, or we could just be
  			 * unmapping part of it.  But we can't really
  			 * get rid of part of a realtime extent.
  			 */
  			if (del.br_state == XFS_EXT_UNWRITTEN) {
  				/*
  				 * This piece is unwritten, or we're not
  				 * using unwritten extents.  Skip over it.
  				 */
  				ASSERT(end >= mod);
  				end -= mod > del.br_blockcount ?
  					del.br_blockcount : mod;
  				if (end < got.br_startoff &&
  				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
  					done = true;
  					break;
  				}
  				continue;
  			}
  			/*
  			 * It's written, turn it unwritten.
  			 * This is better than zeroing it.
  			 */
  			ASSERT(del.br_state == XFS_EXT_NORM);
  			ASSERT(tp->t_blk_res > 0);
  			/*
  			 * If this spans a realtime extent boundary,
  			 * chop it back to the start of the one we end at.
  			 */
  			if (del.br_blockcount > mod) {
  				del.br_startoff += del.br_blockcount - mod;
  				del.br_startblock += del.br_blockcount - mod;
  				del.br_blockcount = mod;
  			}
  			del.br_state = XFS_EXT_UNWRITTEN;
  			error = xfs_bmap_add_extent_unwritten_real(tp, ip,
  					whichfork, &icur, &cur, &del,
  					&logflags);
  			if (error)
  				goto error0;
  			goto nodelete;
  		}
  		div_u64_rem(del.br_startblock, mp->m_sb.sb_rextsize, &mod);
  		if (mod) {
  			/*
  			 * Realtime extent is lined up at the end but not
  			 * at the front.  We'll get rid of full extents if
  			 * we can.
  			 */
  			mod = mp->m_sb.sb_rextsize - mod;
  			if (del.br_blockcount > mod) {
  				del.br_blockcount -= mod;
  				del.br_startoff += mod;
  				del.br_startblock += mod;
  			} else if (del.br_startoff == start &&
  				   (del.br_state == XFS_EXT_UNWRITTEN ||
  				    tp->t_blk_res == 0)) {
  				/*
  				 * Can't make it unwritten.  There isn't
  				 * a full extent here so just skip it.
  				 */
  				ASSERT(end >= del.br_blockcount);
  				end -= del.br_blockcount;
  				if (got.br_startoff > end &&
  				    !xfs_iext_prev_extent(ifp, &icur, &got)) {
  					done = true;
  					break;
  				}
  				continue;
  			} else if (del.br_state == XFS_EXT_UNWRITTEN) {
  				struct xfs_bmbt_irec	prev;
  
  				/*
  				 * This one is already unwritten.
  				 * It must have a written left neighbor.
  				 * Unwrite the killed part of that one and
  				 * try again.
  				 */
  				if (!xfs_iext_prev_extent(ifp, &icur, &prev))
  					ASSERT(0);
  				ASSERT(prev.br_state == XFS_EXT_NORM);
  				ASSERT(!isnullstartblock(prev.br_startblock));
  				ASSERT(del.br_startblock ==
  				       prev.br_startblock + prev.br_blockcount);
  				if (prev.br_startoff < start) {
  					mod = start - prev.br_startoff;
  					prev.br_blockcount -= mod;
  					prev.br_startblock += mod;
  					prev.br_startoff = start;
  				}
  				prev.br_state = XFS_EXT_UNWRITTEN;
  				error = xfs_bmap_add_extent_unwritten_real(tp,
  						ip, whichfork, &icur, &cur,
  						&prev, &logflags);
  				if (error)
  					goto error0;
  				goto nodelete;
  			} else {
  				ASSERT(del.br_state == XFS_EXT_NORM);
  				del.br_state = XFS_EXT_UNWRITTEN;
  				error = xfs_bmap_add_extent_unwritten_real(tp,
  						ip, whichfork, &icur, &cur,
  						&del, &logflags);
  				if (error)
  					goto error0;
  				goto nodelete;
  			}
  		}
  
  delete:
  		if (wasdel) {
  			error = xfs_bmap_del_extent_delay(ip, whichfork, &icur,
  					&got, &del);
  		} else {
  			error = xfs_bmap_del_extent_real(ip, tp, &icur, cur,
  					&del, &tmp_logflags, whichfork,
  					flags);
  			logflags |= tmp_logflags;
  		}
  
  		if (error)
  			goto error0;
  
  		max_len -= del.br_blockcount;
  		end = del.br_startoff - 1;
  nodelete:
  		/*
  		 * If not done go on to the next (previous) record.
  		 */
  		if (end != (xfs_fileoff_t)-1 && end >= start) {
  			if (!xfs_iext_get_extent(ifp, &icur, &got) ||
  			    (got.br_startoff > end &&
  			     !xfs_iext_prev_extent(ifp, &icur, &got))) {
  				done = true;
  				break;
  			}
  			extno++;
  		}
  	}
  	if (done || end == (xfs_fileoff_t)-1 || end < start)
  		*rlen = 0;
  	else
  		*rlen = end - start + 1;
  
  	/*
  	 * Convert to a btree if necessary.
  	 */
  	if (xfs_bmap_needs_btree(ip, whichfork)) {
  		ASSERT(cur == NULL);
  		error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
  				&tmp_logflags, whichfork);
  		logflags |= tmp_logflags;
  	} else {
  		error = xfs_bmap_btree_to_extents(tp, ip, cur, &logflags,
  			whichfork);
  	}
  
  error0:
  	/*
  	 * Log everything.  Do this after conversion, there's no point in
  	 * logging the extent records if we've converted to btree format.
  	 */
  	if ((logflags & xfs_ilog_fext(whichfork)) &&
  	    XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS)
  		logflags &= ~xfs_ilog_fext(whichfork);
  	else if ((logflags & xfs_ilog_fbroot(whichfork)) &&
  		 XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE)
  		logflags &= ~xfs_ilog_fbroot(whichfork);
  	/*
  	 * Log inode even in the error case, if the transaction
  	 * is dirty we'll need to shut down the filesystem.
  	 */
  	if (logflags)
  		xfs_trans_log_inode(tp, ip, logflags);
  	if (cur) {
  		if (!error)
  			cur->bc_private.b.allocated = 0;
  		xfs_btree_del_cursor(cur, error);
  	}
  	return error;
  }
  
  /* Unmap a range of a file. */
  int
  xfs_bunmapi(
  	xfs_trans_t		*tp,
  	struct xfs_inode	*ip,
  	xfs_fileoff_t		bno,
  	xfs_filblks_t		len,
  	int			flags,
  	xfs_extnum_t		nexts,
  	int			*done)
  {
  	int			error;
  
  	error = __xfs_bunmapi(tp, ip, bno, &len, flags, nexts);
  	*done = (len == 0);
  	return error;
  }
  
  /*
   * Determine whether an extent shift can be accomplished by a merge with the
   * extent that precedes the target hole of the shift.
   */
  STATIC bool
  xfs_bmse_can_merge(
  	struct xfs_bmbt_irec	*left,	/* preceding extent */
  	struct xfs_bmbt_irec	*got,	/* current extent to shift */
  	xfs_fileoff_t		shift)	/* shift fsb */
  {
  	xfs_fileoff_t		startoff;
  
  	startoff = got->br_startoff - shift;
  
  	/*
  	 * The extent, once shifted, must be adjacent in-file and on-disk with
  	 * the preceding extent.
  	 */
  	if ((left->br_startoff + left->br_blockcount != startoff) ||
  	    (left->br_startblock + left->br_blockcount != got->br_startblock) ||
  	    (left->br_state != got->br_state) ||
  	    (left->br_blockcount + got->br_blockcount > MAXEXTLEN))
  		return false;
  
  	return true;
  }
  
  /*
   * A bmap extent shift adjusts the file offset of an extent to fill a preceding
   * hole in the file. If an extent shift would result in the extent being fully
   * adjacent to the extent that currently precedes the hole, we can merge with
   * the preceding extent rather than do the shift.
   *
   * This function assumes the caller has verified a shift-by-merge is possible
   * with the provided extents via xfs_bmse_can_merge().
   */
  STATIC int
  xfs_bmse_merge(
  	struct xfs_trans		*tp,
  	struct xfs_inode		*ip,
  	int				whichfork,
  	xfs_fileoff_t			shift,		/* shift fsb */
  	struct xfs_iext_cursor		*icur,
  	struct xfs_bmbt_irec		*got,		/* extent to shift */
  	struct xfs_bmbt_irec		*left,		/* preceding extent */
  	struct xfs_btree_cur		*cur,
  	int				*logflags)	/* output */
  {
  	struct xfs_bmbt_irec		new;
  	xfs_filblks_t			blockcount;
  	int				error, i;
  	struct xfs_mount		*mp = ip->i_mount;
  
  	blockcount = left->br_blockcount + got->br_blockcount;
  
  	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(xfs_bmse_can_merge(left, got, shift));
  
  	new = *left;
  	new.br_blockcount = blockcount;
  
  	/*
  	 * Update the on-disk extent count, the btree if necessary and log the
  	 * inode.
  	 */
  	XFS_IFORK_NEXT_SET(ip, whichfork,
  			   XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
  	*logflags |= XFS_ILOG_CORE;
  	if (!cur) {
  		*logflags |= XFS_ILOG_DEXT;
  		goto done;
  	}
  
  	/* lookup and remove the extent to merge */
  	error = xfs_bmbt_lookup_eq(cur, got, &i);
  	if (error)
  		return error;
  	XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
  
  	error = xfs_btree_delete(cur, &i);
  	if (error)
  		return error;
  	XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
  
  	/* lookup and update size of the previous extent */
  	error = xfs_bmbt_lookup_eq(cur, left, &i);
  	if (error)
  		return error;
  	XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
  
  	error = xfs_bmbt_update(cur, &new);
  	if (error)
  		return error;
  
  done:
  	xfs_iext_remove(ip, icur, 0);
  	xfs_iext_prev(XFS_IFORK_PTR(ip, whichfork), icur);
  	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
  			&new);
  
  	/* update reverse mapping. rmap functions merge the rmaps for us */
  	error = xfs_rmap_unmap_extent(tp, ip, whichfork, got);
  	if (error)
  		return error;
  	memcpy(&new, got, sizeof(new));
  	new.br_startoff = left->br_startoff + left->br_blockcount;
  	return xfs_rmap_map_extent(tp, ip, whichfork, &new);
  }
  
  static int
  xfs_bmap_shift_update_extent(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	int			whichfork,
  	struct xfs_iext_cursor	*icur,
  	struct xfs_bmbt_irec	*got,
  	struct xfs_btree_cur	*cur,
  	int			*logflags,
  	xfs_fileoff_t		startoff)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_bmbt_irec	prev = *got;
  	int			error, i;
  
  	*logflags |= XFS_ILOG_CORE;
  
  	got->br_startoff = startoff;
  
  	if (cur) {
  		error = xfs_bmbt_lookup_eq(cur, &prev, &i);
  		if (error)
  			return error;
  		XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
  
  		error = xfs_bmbt_update(cur, got);
  		if (error)
  			return error;
  	} else {
  		*logflags |= XFS_ILOG_DEXT;
  	}
  
  	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), icur,
  			got);
  
  	/* update reverse mapping */
  	error = xfs_rmap_unmap_extent(tp, ip, whichfork, &prev);
  	if (error)
  		return error;
  	return xfs_rmap_map_extent(tp, ip, whichfork, got);
  }
  
  int
  xfs_bmap_collapse_extents(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	xfs_fileoff_t		*next_fsb,
  	xfs_fileoff_t		offset_shift_fsb,
  	bool			*done)
  {
  	int			whichfork = XFS_DATA_FORK;
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_btree_cur	*cur = NULL;
  	struct xfs_bmbt_irec	got, prev;
  	struct xfs_iext_cursor	icur;
  	xfs_fileoff_t		new_startoff;
  	int			error = 0;
  	int			logflags = 0;
  
  	if (unlikely(XFS_TEST_ERROR(
  	    (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
  	     XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
  	     mp, XFS_ERRTAG_BMAPIFORMAT))) {
  		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, mp);
  		return -EFSCORRUPTED;
  	}
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL));
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(tp, ip, whichfork);
  		if (error)
  			return error;
  	}
  
  	if (ifp->if_flags & XFS_IFBROOT) {
  		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
  		cur->bc_private.b.flags = 0;
  	}
  
  	if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
  		*done = true;
  		goto del_cursor;
  	}
  	XFS_WANT_CORRUPTED_GOTO(mp, !isnullstartblock(got.br_startblock),
  				del_cursor);
  
  	new_startoff = got.br_startoff - offset_shift_fsb;
  	if (xfs_iext_peek_prev_extent(ifp, &icur, &prev)) {
  		if (new_startoff < prev.br_startoff + prev.br_blockcount) {
  			error = -EINVAL;
  			goto del_cursor;
  		}
  
  		if (xfs_bmse_can_merge(&prev, &got, offset_shift_fsb)) {
  			error = xfs_bmse_merge(tp, ip, whichfork,
  					offset_shift_fsb, &icur, &got, &prev,
  					cur, &logflags);
  			if (error)
  				goto del_cursor;
  			goto done;
  		}
  	} else {
  		if (got.br_startoff < offset_shift_fsb) {
  			error = -EINVAL;
  			goto del_cursor;
  		}
  	}
  
  	error = xfs_bmap_shift_update_extent(tp, ip, whichfork, &icur, &got,
  			cur, &logflags, new_startoff);
  	if (error)
  		goto del_cursor;
  
  done:
  	if (!xfs_iext_next_extent(ifp, &icur, &got)) {
  		*done = true;
  		goto del_cursor;
  	}
  
  	*next_fsb = got.br_startoff;
  del_cursor:
  	if (cur)
  		xfs_btree_del_cursor(cur, error);
  	if (logflags)
  		xfs_trans_log_inode(tp, ip, logflags);
  	return error;
  }
  
  /* Make sure we won't be right-shifting an extent past the maximum bound. */
  int
  xfs_bmap_can_insert_extents(
  	struct xfs_inode	*ip,
  	xfs_fileoff_t		off,
  	xfs_fileoff_t		shift)
  {
  	struct xfs_bmbt_irec	got;
  	int			is_empty;
  	int			error = 0;
  
  	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
  
  	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
  		return -EIO;
  
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	error = xfs_bmap_last_extent(NULL, ip, XFS_DATA_FORK, &got, &is_empty);
  	if (!error && !is_empty && got.br_startoff >= off &&
  	    ((got.br_startoff + shift) & BMBT_STARTOFF_MASK) < got.br_startoff)
  		error = -EINVAL;
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  
  	return error;
  }
  
  int
  xfs_bmap_insert_extents(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	xfs_fileoff_t		*next_fsb,
  	xfs_fileoff_t		offset_shift_fsb,
  	bool			*done,
  	xfs_fileoff_t		stop_fsb)
  {
  	int			whichfork = XFS_DATA_FORK;
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
  	struct xfs_btree_cur	*cur = NULL;
  	struct xfs_bmbt_irec	got, next;
  	struct xfs_iext_cursor	icur;
  	xfs_fileoff_t		new_startoff;
  	int			error = 0;
  	int			logflags = 0;
  
  	if (unlikely(XFS_TEST_ERROR(
  	    (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
  	     XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
  	     mp, XFS_ERRTAG_BMAPIFORMAT))) {
  		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, mp);
  		return -EFSCORRUPTED;
  	}
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL));
  
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(tp, ip, whichfork);
  		if (error)
  			return error;
  	}
  
  	if (ifp->if_flags & XFS_IFBROOT) {
  		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
  		cur->bc_private.b.flags = 0;
  	}
  
  	if (*next_fsb == NULLFSBLOCK) {
  		xfs_iext_last(ifp, &icur);
  		if (!xfs_iext_get_extent(ifp, &icur, &got) ||
  		    stop_fsb > got.br_startoff) {
  			*done = true;
  			goto del_cursor;
  		}
  	} else {
  		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &icur, &got)) {
  			*done = true;
  			goto del_cursor;
  		}
  	}
  	XFS_WANT_CORRUPTED_GOTO(mp, !isnullstartblock(got.br_startblock),
  				del_cursor);
  
  	if (stop_fsb >= got.br_startoff + got.br_blockcount) {
  		error = -EIO;
  		goto del_cursor;
  	}
  
  	new_startoff = got.br_startoff + offset_shift_fsb;
  	if (xfs_iext_peek_next_extent(ifp, &icur, &next)) {
  		if (new_startoff + got.br_blockcount > next.br_startoff) {
  			error = -EINVAL;
  			goto del_cursor;
  		}
  
  		/*
  		 * Unlike a left shift (which involves a hole punch), a right
  		 * shift does not modify extent neighbors in any way.  We should
  		 * never find mergeable extents in this scenario.  Check anyways
  		 * and warn if we encounter two extents that could be one.
  		 */
  		if (xfs_bmse_can_merge(&got, &next, offset_shift_fsb))
  			WARN_ON_ONCE(1);
  	}
  
  	error = xfs_bmap_shift_update_extent(tp, ip, whichfork, &icur, &got,
  			cur, &logflags, new_startoff);
  	if (error)
  		goto del_cursor;
  
  	if (!xfs_iext_prev_extent(ifp, &icur, &got) ||
  	    stop_fsb >= got.br_startoff + got.br_blockcount) {
  		*done = true;
  		goto del_cursor;
  	}
  
  	*next_fsb = got.br_startoff;
  del_cursor:
  	if (cur)
  		xfs_btree_del_cursor(cur, error);
  	if (logflags)
  		xfs_trans_log_inode(tp, ip, logflags);
  	return error;
  }
  
  /*
   * Splits an extent into two extents at split_fsb block such that it is the
   * first block of the current_ext. @ext is a target extent to be split.
   * @split_fsb is a block where the extents is split.  If split_fsb lies in a
   * hole or the first block of extents, just return 0.
   */
  STATIC int
  xfs_bmap_split_extent_at(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	xfs_fileoff_t		split_fsb)
  {
  	int				whichfork = XFS_DATA_FORK;
  	struct xfs_btree_cur		*cur = NULL;
  	struct xfs_bmbt_irec		got;
  	struct xfs_bmbt_irec		new; /* split extent */
  	struct xfs_mount		*mp = ip->i_mount;
  	struct xfs_ifork		*ifp;
  	xfs_fsblock_t			gotblkcnt; /* new block count for got */
  	struct xfs_iext_cursor		icur;
  	int				error = 0;
  	int				logflags = 0;
  	int				i = 0;
  
  	if (unlikely(XFS_TEST_ERROR(
  	    (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
  	     XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
  	     mp, XFS_ERRTAG_BMAPIFORMAT))) {
  		XFS_ERROR_REPORT("xfs_bmap_split_extent_at",
  				 XFS_ERRLEVEL_LOW, mp);
  		return -EFSCORRUPTED;
  	}
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
  		/* Read in all the extents */
  		error = xfs_iread_extents(tp, ip, whichfork);
  		if (error)
  			return error;
  	}
  
  	/*
  	 * If there are not extents, or split_fsb lies in a hole we are done.
  	 */
  	if (!xfs_iext_lookup_extent(ip, ifp, split_fsb, &icur, &got) ||
  	    got.br_startoff >= split_fsb)
  		return 0;
  
  	gotblkcnt = split_fsb - got.br_startoff;
  	new.br_startoff = split_fsb;
  	new.br_startblock = got.br_startblock + gotblkcnt;
  	new.br_blockcount = got.br_blockcount - gotblkcnt;
  	new.br_state = got.br_state;
  
  	if (ifp->if_flags & XFS_IFBROOT) {
  		cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
  		cur->bc_private.b.flags = 0;
  		error = xfs_bmbt_lookup_eq(cur, &got, &i);
  		if (error)
  			goto del_cursor;
  		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, del_cursor);
  	}
  
  	got.br_blockcount = gotblkcnt;
  	xfs_iext_update_extent(ip, xfs_bmap_fork_to_state(whichfork), &icur,
  			&got);
  
  	logflags = XFS_ILOG_CORE;
  	if (cur) {
  		error = xfs_bmbt_update(cur, &got);
  		if (error)
  			goto del_cursor;
  	} else
  		logflags |= XFS_ILOG_DEXT;
  
  	/* Add new extent */
  	xfs_iext_next(ifp, &icur);
  	xfs_iext_insert(ip, &icur, &new, 0);
  	XFS_IFORK_NEXT_SET(ip, whichfork,
  			   XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
  
  	if (cur) {
  		error = xfs_bmbt_lookup_eq(cur, &new, &i);
  		if (error)
  			goto del_cursor;
  		XFS_WANT_CORRUPTED_GOTO(mp, i == 0, del_cursor);
  		error = xfs_btree_insert(cur, &i);
  		if (error)
  			goto del_cursor;
  		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, del_cursor);
  	}
  
  	/*
  	 * Convert to a btree if necessary.
  	 */
  	if (xfs_bmap_needs_btree(ip, whichfork)) {
  		int tmp_logflags; /* partial log flag return val */
  
  		ASSERT(cur == NULL);
  		error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0,
  				&tmp_logflags, whichfork);
  		logflags |= tmp_logflags;
  	}
  
  del_cursor:
  	if (cur) {
  		cur->bc_private.b.allocated = 0;
  		xfs_btree_del_cursor(cur, error);
  	}
  
  	if (logflags)
  		xfs_trans_log_inode(tp, ip, logflags);
  	return error;
  }
  
  int
  xfs_bmap_split_extent(
  	struct xfs_inode        *ip,
  	xfs_fileoff_t           split_fsb)
  {
  	struct xfs_mount        *mp = ip->i_mount;
  	struct xfs_trans        *tp;
  	int                     error;
  
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write,
  			XFS_DIOSTRAT_SPACE_RES(mp, 0), 0, 0, &tp);
  	if (error)
  		return error;
  
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
  
  	error = xfs_bmap_split_extent_at(tp, ip, split_fsb);
  	if (error)
  		goto out;
  
  	return xfs_trans_commit(tp);
  
  out:
  	xfs_trans_cancel(tp);
  	return error;
  }
  
  /* Deferred mapping is only for real extents in the data fork. */
  static bool
  xfs_bmap_is_update_needed(
  	struct xfs_bmbt_irec	*bmap)
  {
  	return  bmap->br_startblock != HOLESTARTBLOCK &&
  		bmap->br_startblock != DELAYSTARTBLOCK;
  }
  
  /* Record a bmap intent. */
  static int
  __xfs_bmap_add(
  	struct xfs_trans		*tp,
  	enum xfs_bmap_intent_type	type,
  	struct xfs_inode		*ip,
  	int				whichfork,
  	struct xfs_bmbt_irec		*bmap)
  {
  	struct xfs_bmap_intent		*bi;
  
  	trace_xfs_bmap_defer(tp->t_mountp,
  			XFS_FSB_TO_AGNO(tp->t_mountp, bmap->br_startblock),
  			type,
  			XFS_FSB_TO_AGBNO(tp->t_mountp, bmap->br_startblock),
  			ip->i_ino, whichfork,
  			bmap->br_startoff,
  			bmap->br_blockcount,
  			bmap->br_state);
  
  	bi = kmem_alloc(sizeof(struct xfs_bmap_intent), KM_SLEEP | KM_NOFS);
  	INIT_LIST_HEAD(&bi->bi_list);
  	bi->bi_type = type;
  	bi->bi_owner = ip;
  	bi->bi_whichfork = whichfork;
  	bi->bi_bmap = *bmap;
  
  	xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_BMAP, &bi->bi_list);
  	return 0;
  }
  
  /* Map an extent into a file. */
  int
  xfs_bmap_map_extent(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	struct xfs_bmbt_irec	*PREV)
  {
  	if (!xfs_bmap_is_update_needed(PREV))
  		return 0;
  
  	return __xfs_bmap_add(tp, XFS_BMAP_MAP, ip, XFS_DATA_FORK, PREV);
  }
  
  /* Unmap an extent out of a file. */
  int
  xfs_bmap_unmap_extent(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	struct xfs_bmbt_irec	*PREV)
  {
  	if (!xfs_bmap_is_update_needed(PREV))
  		return 0;
  
  	return __xfs_bmap_add(tp, XFS_BMAP_UNMAP, ip, XFS_DATA_FORK, PREV);
  }
  
  /*
   * Process one of the deferred bmap operations.  We pass back the
   * btree cursor to maintain our lock on the bmapbt between calls.
   */
  int
  xfs_bmap_finish_one(
  	struct xfs_trans		*tp,
  	struct xfs_inode		*ip,
  	enum xfs_bmap_intent_type	type,
  	int				whichfork,
  	xfs_fileoff_t			startoff,
  	xfs_fsblock_t			startblock,
  	xfs_filblks_t			*blockcount,
  	xfs_exntst_t			state)
  {
  	int				error = 0;
  
  	ASSERT(tp->t_firstblock == NULLFSBLOCK);
  
  	trace_xfs_bmap_deferred(tp->t_mountp,
  			XFS_FSB_TO_AGNO(tp->t_mountp, startblock), type,
  			XFS_FSB_TO_AGBNO(tp->t_mountp, startblock),
  			ip->i_ino, whichfork, startoff, *blockcount, state);
  
  	if (WARN_ON_ONCE(whichfork != XFS_DATA_FORK))
  		return -EFSCORRUPTED;
  
  	if (XFS_TEST_ERROR(false, tp->t_mountp,
  			XFS_ERRTAG_BMAP_FINISH_ONE))
  		return -EIO;
  
  	switch (type) {
  	case XFS_BMAP_MAP:
  		error = xfs_bmapi_remap(tp, ip, startoff, *blockcount,
  				startblock, 0);
  		*blockcount = 0;
  		break;
  	case XFS_BMAP_UNMAP:
  		error = __xfs_bunmapi(tp, ip, startoff, blockcount,
  				XFS_BMAPI_REMAP, 1);
  		break;
  	default:
  		ASSERT(0);
  		error = -EFSCORRUPTED;
  	}
  
  	return error;
  }
  
  /* Check that an inode's extent does not have invalid flags or bad ranges. */
  xfs_failaddr_t
  xfs_bmap_validate_extent(
  	struct xfs_inode	*ip,
  	int			whichfork,
  	struct xfs_bmbt_irec	*irec)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	xfs_fsblock_t		endfsb;
  	bool			isrt;
  
  	isrt = XFS_IS_REALTIME_INODE(ip);
  	endfsb = irec->br_startblock + irec->br_blockcount - 1;
  	if (isrt) {
  		if (!xfs_verify_rtbno(mp, irec->br_startblock))
  			return __this_address;
  		if (!xfs_verify_rtbno(mp, endfsb))
  			return __this_address;
  	} else {
  		if (!xfs_verify_fsbno(mp, irec->br_startblock))
  			return __this_address;
  		if (!xfs_verify_fsbno(mp, endfsb))
  			return __this_address;
  		if (XFS_FSB_TO_AGNO(mp, irec->br_startblock) !=
  		    XFS_FSB_TO_AGNO(mp, endfsb))
  			return __this_address;
  	}
  	if (irec->br_state != XFS_EXT_NORM && whichfork != XFS_DATA_FORK)
  		return __this_address;
  	return NULL;
  }
  