/*

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

   *

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

   * published by the Free Software Foundation.
   *

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

   *

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

   */

  #include "xfs.h"

  #include "xfs_fs.h"

  #include "xfs_types.h"

  #include "xfs_bit.h"

  #include "xfs_log.h"

  #include "xfs_inum.h"

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

  #include "xfs_dir2.h"

  #include "xfs_mount.h"

  #include "xfs_bmap_btree.h"

  #include "xfs_dinode.h"
  #include "xfs_inode.h"
  #include "xfs_alloc.h"
  #include "xfs_bmap.h"

  #include "xfs_rtalloc.h"
  #include "xfs_fsops.h"
  #include "xfs_error.h"
  #include "xfs_rw.h"
  #include "xfs_inode_item.h"
  #include "xfs_trans_space.h"

  #include "xfs_utils.h"

  #include "xfs_trace.h"

  #include "xfs_buf.h"

  
  
  /*
   * Prototypes for internal functions.
   */
  
  
  STATIC int xfs_rtallocate_range(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
  		xfs_extlen_t, xfs_buf_t **, xfs_fsblock_t *);
  STATIC int xfs_rtany_summary(xfs_mount_t *, xfs_trans_t *, int, int,
  		xfs_rtblock_t, xfs_buf_t **, xfs_fsblock_t *, int *);
  STATIC int xfs_rtcheck_range(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
  		xfs_extlen_t, int, xfs_rtblock_t *, int *);
  STATIC int xfs_rtfind_back(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
  		xfs_rtblock_t, xfs_rtblock_t *);
  STATIC int xfs_rtfind_forw(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
  		xfs_rtblock_t, xfs_rtblock_t *);
  STATIC int xfs_rtget_summary( xfs_mount_t *, xfs_trans_t *, int,
  		xfs_rtblock_t, xfs_buf_t **, xfs_fsblock_t *, xfs_suminfo_t *);
  STATIC int xfs_rtmodify_range(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
  		xfs_extlen_t, int);
  STATIC int xfs_rtmodify_summary(xfs_mount_t *, xfs_trans_t *, int,
  		xfs_rtblock_t, int, xfs_buf_t **, xfs_fsblock_t *);
  
  /*
   * Internal functions.
   */
  
  /*

   * Allocate space to the bitmap or summary file, and zero it, for growfs.
   */
  STATIC int				/* error */
  xfs_growfs_rt_alloc(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_extlen_t	oblocks,	/* old count of blocks */
  	xfs_extlen_t	nblocks,	/* new count of blocks */

  	xfs_inode_t	*ip)		/* inode (bitmap/summary) */

  {
  	xfs_fileoff_t	bno;		/* block number in file */
  	xfs_buf_t	*bp;		/* temporary buffer for zeroing */

  	int		committed;	/* transaction committed flag */
  	xfs_daddr_t	d;		/* disk block address */
  	int		error;		/* error return value */
  	xfs_fsblock_t	firstblock;	/* first block allocated in xaction */
  	xfs_bmap_free_t	flist;		/* list of freed blocks */
  	xfs_fsblock_t	fsbno;		/* filesystem block for bno */

  	xfs_bmbt_irec_t	map;		/* block map output */
  	int		nmap;		/* number of block maps */
  	int		resblks;	/* space reservation */

  
  	/*
  	 * Allocate space to the file, as necessary.
  	 */
  	while (oblocks < nblocks) {

  		int		cancelflags = 0;
  		xfs_trans_t	*tp;

  		tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFSRT_ALLOC);
  		resblks = XFS_GROWFSRT_SPACE_RES(mp, nblocks - oblocks);

  		/*
  		 * Reserve space & log for one extent added to the file.
  		 */
  		if ((error = xfs_trans_reserve(tp, resblks,
  				XFS_GROWRTALLOC_LOG_RES(mp), 0,
  				XFS_TRANS_PERM_LOG_RES,
  				XFS_DEFAULT_PERM_LOG_COUNT)))

  			goto error_cancel;

  		cancelflags = XFS_TRANS_RELEASE_LOG_RES;
  		/*
  		 * Lock the inode.
  		 */

  		xfs_ilock(ip, XFS_ILOCK_EXCL);

  		xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

  		xfs_bmap_init(&flist, &firstblock);

  		/*
  		 * Allocate blocks to the bitmap file.
  		 */
  		nmap = 1;
  		cancelflags |= XFS_TRANS_ABORT;

  		error = xfs_bmapi_write(tp, ip, oblocks, nblocks - oblocks,
  					XFS_BMAPI_METADATA, &firstblock,
  					resblks, &map, &nmap, &flist);

  		if (!error && nmap < 1)
  			error = XFS_ERROR(ENOSPC);
  		if (error)

  			goto error_cancel;

  		/*
  		 * Free any blocks freed up in the transaction, then commit.
  		 */

  		error = xfs_bmap_finish(&tp, &flist, &committed);

  		if (error)

  			goto error_cancel;
  		error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
  		if (error)
  			goto error;

  		/*
  		 * Now we need to clear the allocated blocks.
  		 * Do this one block per transaction, to keep it simple.
  		 */
  		cancelflags = 0;
  		for (bno = map.br_startoff, fsbno = map.br_startblock;
  		     bno < map.br_startoff + map.br_blockcount;
  		     bno++, fsbno++) {
  			tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFSRT_ZERO);
  			/*
  			 * Reserve log for one block zeroing.
  			 */
  			if ((error = xfs_trans_reserve(tp, 0,
  					XFS_GROWRTZERO_LOG_RES(mp), 0, 0, 0)))

  				goto error_cancel;

  			/*
  			 * Lock the bitmap inode.
  			 */

  			xfs_ilock(ip, XFS_ILOCK_EXCL);

  			xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

  			/*
  			 * Get a buffer for the block.
  			 */
  			d = XFS_FSB_TO_DADDR(mp, fsbno);
  			bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
  				mp->m_bsize, 0);
  			if (bp == NULL) {
  				error = XFS_ERROR(EIO);

  error_cancel:
  				xfs_trans_cancel(tp, cancelflags);
  				goto error;

  			}

  			memset(bp->b_addr, 0, mp->m_sb.sb_blocksize);

  			xfs_trans_log_buf(tp, bp, 0, mp->m_sb.sb_blocksize - 1);
  			/*
  			 * Commit the transaction.
  			 */

  			error = xfs_trans_commit(tp, 0);
  			if (error)
  				goto error;

  		}
  		/*
  		 * Go on to the next extent, if any.
  		 */
  		oblocks = map.br_startoff + map.br_blockcount;
  	}
  	return 0;

  error:

  	return error;
  }
  
  /*
   * Attempt to allocate an extent minlen<=len<=maxlen starting from
   * bitmap block bbno.  If we don't get maxlen then use prod to trim
   * the length, if given.  Returns error; returns starting block in *rtblock.
   * The lengths are all in rtextents.
   */
  STATIC int				/* error */
  xfs_rtallocate_extent_block(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	bbno,		/* bitmap block number */
  	xfs_extlen_t	minlen,		/* minimum length to allocate */
  	xfs_extlen_t	maxlen,		/* maximum length to allocate */
  	xfs_extlen_t	*len,		/* out: actual length allocated */
  	xfs_rtblock_t	*nextp,		/* out: next block to try */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
  	xfs_extlen_t	prod,		/* extent product factor */
  	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
  {
  	xfs_rtblock_t	besti;		/* best rtblock found so far */
  	xfs_rtblock_t	bestlen;	/* best length found so far */
  	xfs_rtblock_t	end;		/* last rtblock in chunk */
  	int		error;		/* error value */
  	xfs_rtblock_t	i;		/* current rtblock trying */
  	xfs_rtblock_t	next;		/* next rtblock to try */
  	int		stat;		/* status from internal calls */
  
  	/*
  	 * Loop over all the extents starting in this bitmap block,
  	 * looking for one that's long enough.
  	 */
  	for (i = XFS_BLOCKTOBIT(mp, bbno), besti = -1, bestlen = 0,
  		end = XFS_BLOCKTOBIT(mp, bbno + 1) - 1;
  	     i <= end;
  	     i++) {
  		/*
  		 * See if there's a free extent of maxlen starting at i.
  		 * If it's not so then next will contain the first non-free.
  		 */
  		error = xfs_rtcheck_range(mp, tp, i, maxlen, 1, &next, &stat);
  		if (error) {
  			return error;
  		}
  		if (stat) {
  			/*
  			 * i for maxlen is all free, allocate and return that.
  			 */
  			error = xfs_rtallocate_range(mp, tp, i, maxlen, rbpp,
  				rsb);
  			if (error) {
  				return error;
  			}
  			*len = maxlen;
  			*rtblock = i;
  			return 0;
  		}
  		/*
  		 * In the case where we have a variable-sized allocation
  		 * request, figure out how big this free piece is,
  		 * and if it's big enough for the minimum, and the best
  		 * so far, remember it.
  		 */
  		if (minlen < maxlen) {
  			xfs_rtblock_t	thislen;	/* this extent size */
  
  			thislen = next - i;
  			if (thislen >= minlen && thislen > bestlen) {
  				besti = i;
  				bestlen = thislen;
  			}
  		}
  		/*
  		 * If not done yet, find the start of the next free space.
  		 */
  		if (next < end) {
  			error = xfs_rtfind_forw(mp, tp, next, end, &i);
  			if (error) {
  				return error;
  			}
  		} else
  			break;
  	}
  	/*
  	 * Searched the whole thing & didn't find a maxlen free extent.
  	 */
  	if (minlen < maxlen && besti != -1) {
  		xfs_extlen_t	p;	/* amount to trim length by */
  
  		/*
  		 * If size should be a multiple of prod, make that so.
  		 */
  		if (prod > 1 && (p = do_mod(bestlen, prod)))
  			bestlen -= p;
  		/*
  		 * Allocate besti for bestlen & return that.
  		 */
  		error = xfs_rtallocate_range(mp, tp, besti, bestlen, rbpp, rsb);
  		if (error) {
  			return error;
  		}
  		*len = bestlen;
  		*rtblock = besti;
  		return 0;
  	}
  	/*
  	 * Allocation failed.  Set *nextp to the next block to try.
  	 */
  	*nextp = next;
  	*rtblock = NULLRTBLOCK;
  	return 0;
  }
  
  /*
   * Allocate an extent of length minlen<=len<=maxlen, starting at block
   * bno.  If we don't get maxlen then use prod to trim the length, if given.
   * Returns error; returns starting block in *rtblock.
   * The lengths are all in rtextents.
   */
  STATIC int				/* error */
  xfs_rtallocate_extent_exact(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	bno,		/* starting block number to allocate */
  	xfs_extlen_t	minlen,		/* minimum length to allocate */
  	xfs_extlen_t	maxlen,		/* maximum length to allocate */
  	xfs_extlen_t	*len,		/* out: actual length allocated */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
  	xfs_extlen_t	prod,		/* extent product factor */
  	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
  {
  	int		error;		/* error value */
  	xfs_extlen_t	i;		/* extent length trimmed due to prod */
  	int		isfree;		/* extent is free */
  	xfs_rtblock_t	next;		/* next block to try (dummy) */
  
  	ASSERT(minlen % prod == 0 && maxlen % prod == 0);
  	/*
  	 * Check if the range in question (for maxlen) is free.
  	 */
  	error = xfs_rtcheck_range(mp, tp, bno, maxlen, 1, &next, &isfree);
  	if (error) {
  		return error;
  	}
  	if (isfree) {
  		/*
  		 * If it is, allocate it and return success.
  		 */
  		error = xfs_rtallocate_range(mp, tp, bno, maxlen, rbpp, rsb);
  		if (error) {
  			return error;
  		}
  		*len = maxlen;
  		*rtblock = bno;
  		return 0;
  	}
  	/*
  	 * If not, allocate what there is, if it's at least minlen.
  	 */
  	maxlen = next - bno;
  	if (maxlen < minlen) {
  		/*
  		 * Failed, return failure status.
  		 */
  		*rtblock = NULLRTBLOCK;
  		return 0;
  	}
  	/*
  	 * Trim off tail of extent, if prod is specified.
  	 */
  	if (prod > 1 && (i = maxlen % prod)) {
  		maxlen -= i;
  		if (maxlen < minlen) {
  			/*
  			 * Now we can't do it, return failure status.
  			 */
  			*rtblock = NULLRTBLOCK;
  			return 0;
  		}
  	}
  	/*
  	 * Allocate what we can and return it.
  	 */
  	error = xfs_rtallocate_range(mp, tp, bno, maxlen, rbpp, rsb);
  	if (error) {
  		return error;
  	}
  	*len = maxlen;
  	*rtblock = bno;
  	return 0;
  }
  
  /*
   * Allocate an extent of length minlen<=len<=maxlen, starting as near
   * to bno as possible.  If we don't get maxlen then use prod to trim
   * the length, if given.  The lengths are all in rtextents.
   */
  STATIC int				/* error */
  xfs_rtallocate_extent_near(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	bno,		/* starting block number to allocate */
  	xfs_extlen_t	minlen,		/* minimum length to allocate */
  	xfs_extlen_t	maxlen,		/* maximum length to allocate */
  	xfs_extlen_t	*len,		/* out: actual length allocated */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
  	xfs_extlen_t	prod,		/* extent product factor */
  	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
  {
  	int		any;		/* any useful extents from summary */
  	xfs_rtblock_t	bbno;		/* bitmap block number */
  	int		error;		/* error value */
  	int		i;		/* bitmap block offset (loop control) */
  	int		j;		/* secondary loop control */
  	int		log2len;	/* log2 of minlen */
  	xfs_rtblock_t	n;		/* next block to try */
  	xfs_rtblock_t	r;		/* result block */
  
  	ASSERT(minlen % prod == 0 && maxlen % prod == 0);
  	/*
  	 * If the block number given is off the end, silently set it to
  	 * the last block.
  	 */
  	if (bno >= mp->m_sb.sb_rextents)
  		bno = mp->m_sb.sb_rextents - 1;
  	/*
  	 * Try the exact allocation first.
  	 */
  	error = xfs_rtallocate_extent_exact(mp, tp, bno, minlen, maxlen, len,
  		rbpp, rsb, prod, &r);
  	if (error) {
  		return error;
  	}
  	/*
  	 * If the exact allocation worked, return that.
  	 */
  	if (r != NULLRTBLOCK) {
  		*rtblock = r;
  		return 0;
  	}
  	bbno = XFS_BITTOBLOCK(mp, bno);
  	i = 0;

  	ASSERT(minlen != 0);

  	log2len = xfs_highbit32(minlen);
  	/*
  	 * Loop over all bitmap blocks (bbno + i is current block).
  	 */
  	for (;;) {
  		/*
  		 * Get summary information of extents of all useful levels
  		 * starting in this bitmap block.
  		 */
  		error = xfs_rtany_summary(mp, tp, log2len, mp->m_rsumlevels - 1,
  			bbno + i, rbpp, rsb, &any);
  		if (error) {
  			return error;
  		}
  		/*
  		 * If there are any useful extents starting here, try
  		 * allocating one.
  		 */
  		if (any) {
  			/*
  			 * On the positive side of the starting location.
  			 */
  			if (i >= 0) {
  				/*
  				 * Try to allocate an extent starting in
  				 * this block.
  				 */
  				error = xfs_rtallocate_extent_block(mp, tp,
  					bbno + i, minlen, maxlen, len, &n, rbpp,
  					rsb, prod, &r);
  				if (error) {
  					return error;
  				}
  				/*
  				 * If it worked, return it.
  				 */
  				if (r != NULLRTBLOCK) {
  					*rtblock = r;
  					return 0;
  				}
  			}
  			/*
  			 * On the negative side of the starting location.
  			 */
  			else {		/* i < 0 */
  				/*
  				 * Loop backwards through the bitmap blocks from
  				 * the starting point-1 up to where we are now.
  				 * There should be an extent which ends in this
  				 * bitmap block and is long enough.
  				 */
  				for (j = -1; j > i; j--) {
  					/*
  					 * Grab the summary information for
  					 * this bitmap block.
  					 */
  					error = xfs_rtany_summary(mp, tp,
  						log2len, mp->m_rsumlevels - 1,
  						bbno + j, rbpp, rsb, &any);
  					if (error) {
  						return error;
  					}
  					/*
  					 * If there's no extent given in the
  					 * summary that means the extent we
  					 * found must carry over from an
  					 * earlier block.  If there is an
  					 * extent given, we've already tried
  					 * that allocation, don't do it again.
  					 */
  					if (any)
  						continue;
  					error = xfs_rtallocate_extent_block(mp,
  						tp, bbno + j, minlen, maxlen,
  						len, &n, rbpp, rsb, prod, &r);
  					if (error) {
  						return error;
  					}
  					/*
  					 * If it works, return the extent.
  					 */
  					if (r != NULLRTBLOCK) {
  						*rtblock = r;
  						return 0;
  					}
  				}
  				/*
  				 * There weren't intervening bitmap blocks
  				 * with a long enough extent, or the
  				 * allocation didn't work for some reason
  				 * (i.e. it's a little * too short).
  				 * Try to allocate from the summary block
  				 * that we found.
  				 */
  				error = xfs_rtallocate_extent_block(mp, tp,
  					bbno + i, minlen, maxlen, len, &n, rbpp,
  					rsb, prod, &r);
  				if (error) {
  					return error;
  				}
  				/*
  				 * If it works, return the extent.
  				 */
  				if (r != NULLRTBLOCK) {
  					*rtblock = r;
  					return 0;
  				}
  			}
  		}
  		/*
  		 * Loop control.  If we were on the positive side, and there's
  		 * still more blocks on the negative side, go there.
  		 */
  		if (i > 0 && (int)bbno - i >= 0)
  			i = -i;
  		/*
  		 * If positive, and no more negative, but there are more
  		 * positive, go there.
  		 */
  		else if (i > 0 && (int)bbno + i < mp->m_sb.sb_rbmblocks - 1)
  			i++;
  		/*
  		 * If negative or 0 (just started), and there are positive
  		 * blocks to go, go there.  The 0 case moves to block 1.
  		 */
  		else if (i <= 0 && (int)bbno - i < mp->m_sb.sb_rbmblocks - 1)
  			i = 1 - i;
  		/*
  		 * If negative or 0 and there are more negative blocks,
  		 * go there.
  		 */
  		else if (i <= 0 && (int)bbno + i > 0)
  			i--;
  		/*
  		 * Must be done.  Return failure.
  		 */
  		else
  			break;
  	}
  	*rtblock = NULLRTBLOCK;
  	return 0;
  }
  
  /*
   * Allocate an extent of length minlen<=len<=maxlen, with no position
   * specified.  If we don't get maxlen then use prod to trim
   * the length, if given.  The lengths are all in rtextents.
   */
  STATIC int				/* error */
  xfs_rtallocate_extent_size(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_extlen_t	minlen,		/* minimum length to allocate */
  	xfs_extlen_t	maxlen,		/* maximum length to allocate */
  	xfs_extlen_t	*len,		/* out: actual length allocated */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
  	xfs_extlen_t	prod,		/* extent product factor */
  	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
  {
  	int		error;		/* error value */
  	int		i;		/* bitmap block number */
  	int		l;		/* level number (loop control) */
  	xfs_rtblock_t	n;		/* next block to be tried */
  	xfs_rtblock_t	r;		/* result block number */
  	xfs_suminfo_t	sum;		/* summary information for extents */
  
  	ASSERT(minlen % prod == 0 && maxlen % prod == 0);

  	ASSERT(maxlen != 0);

  	/*
  	 * Loop over all the levels starting with maxlen.
  	 * At each level, look at all the bitmap blocks, to see if there
  	 * are extents starting there that are long enough (>= maxlen).
  	 * Note, only on the initial level can the allocation fail if
  	 * the summary says there's an extent.
  	 */
  	for (l = xfs_highbit32(maxlen); l < mp->m_rsumlevels; l++) {
  		/*
  		 * Loop over all the bitmap blocks.
  		 */
  		for (i = 0; i < mp->m_sb.sb_rbmblocks; i++) {
  			/*
  			 * Get the summary for this level/block.
  			 */
  			error = xfs_rtget_summary(mp, tp, l, i, rbpp, rsb,
  				&sum);
  			if (error) {
  				return error;
  			}
  			/*
  			 * Nothing there, on to the next block.
  			 */
  			if (!sum)
  				continue;
  			/*
  			 * Try allocating the extent.
  			 */
  			error = xfs_rtallocate_extent_block(mp, tp, i, maxlen,
  				maxlen, len, &n, rbpp, rsb, prod, &r);
  			if (error) {
  				return error;
  			}
  			/*
  			 * If it worked, return that.
  			 */
  			if (r != NULLRTBLOCK) {
  				*rtblock = r;
  				return 0;
  			}
  			/*
  			 * If the "next block to try" returned from the
  			 * allocator is beyond the next bitmap block,
  			 * skip to that bitmap block.
  			 */
  			if (XFS_BITTOBLOCK(mp, n) > i + 1)
  				i = XFS_BITTOBLOCK(mp, n) - 1;
  		}
  	}
  	/*
  	 * Didn't find any maxlen blocks.  Try smaller ones, unless
  	 * we're asking for a fixed size extent.
  	 */
  	if (minlen > --maxlen) {
  		*rtblock = NULLRTBLOCK;
  		return 0;
  	}

  	ASSERT(minlen != 0);
  	ASSERT(maxlen != 0);

  	/*
  	 * Loop over sizes, from maxlen down to minlen.
  	 * This time, when we do the allocations, allow smaller ones
  	 * to succeed.
  	 */
  	for (l = xfs_highbit32(maxlen); l >= xfs_highbit32(minlen); l--) {
  		/*
  		 * Loop over all the bitmap blocks, try an allocation
  		 * starting in that block.
  		 */
  		for (i = 0; i < mp->m_sb.sb_rbmblocks; i++) {
  			/*
  			 * Get the summary information for this level/block.
  			 */
  			error =	xfs_rtget_summary(mp, tp, l, i, rbpp, rsb,
  						  &sum);
  			if (error) {
  				return error;
  			}
  			/*
  			 * If nothing there, go on to next.
  			 */
  			if (!sum)
  				continue;
  			/*
  			 * Try the allocation.  Make sure the specified
  			 * minlen/maxlen are in the possible range for
  			 * this summary level.
  			 */
  			error = xfs_rtallocate_extent_block(mp, tp, i,
  					XFS_RTMAX(minlen, 1 << l),
  					XFS_RTMIN(maxlen, (1 << (l + 1)) - 1),
  					len, &n, rbpp, rsb, prod, &r);
  			if (error) {
  				return error;
  			}
  			/*
  			 * If it worked, return that extent.
  			 */
  			if (r != NULLRTBLOCK) {
  				*rtblock = r;
  				return 0;
  			}
  			/*
  			 * If the "next block to try" returned from the
  			 * allocator is beyond the next bitmap block,
  			 * skip to that bitmap block.
  			 */
  			if (XFS_BITTOBLOCK(mp, n) > i + 1)
  				i = XFS_BITTOBLOCK(mp, n) - 1;
  		}
  	}
  	/*
  	 * Got nothing, return failure.
  	 */
  	*rtblock = NULLRTBLOCK;
  	return 0;
  }
  
  /*
   * Mark an extent specified by start and len allocated.
   * Updates all the summary information as well as the bitmap.
   */
  STATIC int				/* error */
  xfs_rtallocate_range(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	start,		/* start block to allocate */
  	xfs_extlen_t	len,		/* length to allocate */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb)		/* in/out: summary block number */
  {
  	xfs_rtblock_t	end;		/* end of the allocated extent */
  	int		error;		/* error value */
  	xfs_rtblock_t	postblock;	/* first block allocated > end */
  	xfs_rtblock_t	preblock;	/* first block allocated < start */
  
  	end = start + len - 1;
  	/*
  	 * Assume we're allocating out of the middle of a free extent.
  	 * We need to find the beginning and end of the extent so we can
  	 * properly update the summary.
  	 */
  	error = xfs_rtfind_back(mp, tp, start, 0, &preblock);
  	if (error) {
  		return error;
  	}
  	/*
  	 * Find the next allocated block (end of free extent).
  	 */
  	error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
  		&postblock);
  	if (error) {
  		return error;
  	}
  	/*
  	 * Decrement the summary information corresponding to the entire
  	 * (old) free extent.
  	 */
  	error = xfs_rtmodify_summary(mp, tp,
  		XFS_RTBLOCKLOG(postblock + 1 - preblock),
  		XFS_BITTOBLOCK(mp, preblock), -1, rbpp, rsb);
  	if (error) {
  		return error;
  	}
  	/*
  	 * If there are blocks not being allocated at the front of the
  	 * old extent, add summary data for them to be free.
  	 */
  	if (preblock < start) {
  		error = xfs_rtmodify_summary(mp, tp,
  			XFS_RTBLOCKLOG(start - preblock),
  			XFS_BITTOBLOCK(mp, preblock), 1, rbpp, rsb);
  		if (error) {
  			return error;
  		}
  	}
  	/*
  	 * If there are blocks not being allocated at the end of the
  	 * old extent, add summary data for them to be free.
  	 */
  	if (postblock > end) {
  		error = xfs_rtmodify_summary(mp, tp,
  			XFS_RTBLOCKLOG(postblock - end),
  			XFS_BITTOBLOCK(mp, end + 1), 1, rbpp, rsb);
  		if (error) {
  			return error;
  		}
  	}
  	/*
  	 * Modify the bitmap to mark this extent allocated.
  	 */
  	error = xfs_rtmodify_range(mp, tp, start, len, 0);
  	return error;
  }
  
  /*
   * Return whether there are any free extents in the size range given
   * by low and high, for the bitmap block bbno.
   */
  STATIC int				/* error */
  xfs_rtany_summary(
  	xfs_mount_t	*mp,		/* file system mount structure */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	int		low,		/* low log2 extent size */
  	int		high,		/* high log2 extent size */
  	xfs_rtblock_t	bbno,		/* bitmap block number */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
  	int		*stat)		/* out: any good extents here? */
  {
  	int		error;		/* error value */
  	int		log;		/* loop counter, log2 of ext. size */
  	xfs_suminfo_t	sum;		/* summary data */
  
  	/*
  	 * Loop over logs of extent sizes.  Order is irrelevant.
  	 */
  	for (log = low; log <= high; log++) {
  		/*
  		 * Get one summary datum.
  		 */
  		error = xfs_rtget_summary(mp, tp, log, bbno, rbpp, rsb, &sum);
  		if (error) {
  			return error;
  		}
  		/*
  		 * If there are any, return success.
  		 */
  		if (sum) {
  			*stat = 1;
  			return 0;
  		}
  	}
  	/*
  	 * Found nothing, return failure.
  	 */
  	*stat = 0;
  	return 0;
  }
  
  /*
   * Get a buffer for the bitmap or summary file block specified.
   * The buffer is returned read and locked.
   */
  STATIC int				/* error */
  xfs_rtbuf_get(
  	xfs_mount_t	*mp,		/* file system mount structure */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	block,		/* block number in bitmap or summary */
  	int		issum,		/* is summary not bitmap */
  	xfs_buf_t	**bpp)		/* output: buffer for the block */
  {
  	xfs_buf_t	*bp;		/* block buffer, result */

  	xfs_inode_t	*ip;		/* bitmap or summary inode */

  	xfs_bmbt_irec_t	map;
  	int		nmap;
  	int		error;		/* error value */

  
  	ip = issum ? mp->m_rsumip : mp->m_rbmip;

  
  	error = xfs_bmapi_read(ip, block, 1, &map, &nmap, XFS_DATA_FORK);
  	if (error)

  		return error;

  
  	ASSERT(map.br_startblock != NULLFSBLOCK);
  	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
  				   XFS_FSB_TO_DADDR(mp, map.br_startblock),

  				   mp->m_bsize, 0, &bp);

  	if (error)

  		return error;

  	ASSERT(!xfs_buf_geterror(bp));

  	*bpp = bp;
  	return 0;
  }
  
  #ifdef DEBUG
  /*
   * Check that the given extent (block range) is allocated already.
   */
  STATIC int				/* error */
  xfs_rtcheck_alloc_range(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	bno,		/* starting block number of extent */
  	xfs_extlen_t	len,		/* length of extent */
  	int		*stat)		/* out: 1 for allocated, 0 for not */
  {
  	xfs_rtblock_t	new;		/* dummy for xfs_rtcheck_range */
  
  	return xfs_rtcheck_range(mp, tp, bno, len, 0, &new, stat);
  }
  #endif

  /*
   * Check that the given range is either all allocated (val = 0) or
   * all free (val = 1).
   */
  STATIC int				/* error */
  xfs_rtcheck_range(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	start,		/* starting block number of extent */
  	xfs_extlen_t	len,		/* length of extent */
  	int		val,		/* 1 for free, 0 for allocated */
  	xfs_rtblock_t	*new,		/* out: first block not matching */
  	int		*stat)		/* out: 1 for matches, 0 for not */
  {
  	xfs_rtword_t	*b;		/* current word in buffer */
  	int		bit;		/* bit number in the word */
  	xfs_rtblock_t	block;		/* bitmap block number */
  	xfs_buf_t	*bp;		/* buf for the block */
  	xfs_rtword_t	*bufp;		/* starting word in buffer */
  	int		error;		/* error value */
  	xfs_rtblock_t	i;		/* current bit number rel. to start */
  	xfs_rtblock_t	lastbit;	/* last useful bit in word */
  	xfs_rtword_t	mask;		/* mask of relevant bits for value */
  	xfs_rtword_t	wdiff;		/* difference from wanted value */
  	int		word;		/* word number in the buffer */
  
  	/*
  	 * Compute starting bitmap block number
  	 */
  	block = XFS_BITTOBLOCK(mp, start);
  	/*
  	 * Read the bitmap block.
  	 */
  	error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
  	if (error) {
  		return error;
  	}

  	bufp = bp->b_addr;

  	/*
  	 * Compute the starting word's address, and starting bit.
  	 */
  	word = XFS_BITTOWORD(mp, start);
  	b = &bufp[word];
  	bit = (int)(start & (XFS_NBWORD - 1));
  	/*
  	 * 0 (allocated) => all zero's; 1 (free) => all one's.
  	 */
  	val = -val;
  	/*
  	 * If not starting on a word boundary, deal with the first
  	 * (partial) word.
  	 */
  	if (bit) {
  		/*
  		 * Compute first bit not examined.
  		 */
  		lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
  		/*
  		 * Mask of relevant bits.
  		 */
  		mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
  		/*
  		 * Compute difference between actual and desired value.
  		 */
  		if ((wdiff = (*b ^ val) & mask)) {
  			/*
  			 * Different, compute first wrong bit and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i = XFS_RTLOBIT(wdiff) - bit;
  			*new = start + i;
  			*stat = 0;
  			return 0;
  		}
  		i = lastbit - bit;
  		/*
  		 * Go on to next block if that's where the next word is
  		 * and we need the next word.
  		 */
  		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
  			/*
  			 * If done with this block, get the next one.
  			 */
  			xfs_trans_brelse(tp, bp);
  			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
  			if (error) {
  				return error;
  			}

  			b = bufp = bp->b_addr;

  			word = 0;
  		} else {
  			/*
  			 * Go on to the next word in the buffer.
  			 */
  			b++;
  		}
  	} else {
  		/*
  		 * Starting on a word boundary, no partial word.
  		 */
  		i = 0;
  	}
  	/*
  	 * Loop over whole words in buffers.  When we use up one buffer
  	 * we move on to the next one.
  	 */
  	while (len - i >= XFS_NBWORD) {
  		/*
  		 * Compute difference between actual and desired value.
  		 */
  		if ((wdiff = *b ^ val)) {
  			/*
  			 * Different, compute first wrong bit and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i += XFS_RTLOBIT(wdiff);
  			*new = start + i;
  			*stat = 0;
  			return 0;
  		}
  		i += XFS_NBWORD;
  		/*
  		 * Go on to next block if that's where the next word is
  		 * and we need the next word.
  		 */
  		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
  			/*
  			 * If done with this block, get the next one.
  			 */
  			xfs_trans_brelse(tp, bp);
  			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
  			if (error) {
  				return error;
  			}

  			b = bufp = bp->b_addr;

  			word = 0;
  		} else {
  			/*
  			 * Go on to the next word in the buffer.
  			 */
  			b++;
  		}
  	}
  	/*
  	 * If not ending on a word boundary, deal with the last
  	 * (partial) word.
  	 */
  	if ((lastbit = len - i)) {
  		/*
  		 * Mask of relevant bits.
  		 */
  		mask = ((xfs_rtword_t)1 << lastbit) - 1;
  		/*
  		 * Compute difference between actual and desired value.
  		 */
  		if ((wdiff = (*b ^ val) & mask)) {
  			/*
  			 * Different, compute first wrong bit and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i += XFS_RTLOBIT(wdiff);
  			*new = start + i;
  			*stat = 0;
  			return 0;
  		} else
  			i = len;
  	}
  	/*
  	 * Successful, return.
  	 */
  	xfs_trans_brelse(tp, bp);
  	*new = start + i;
  	*stat = 1;
  	return 0;
  }
  
  /*
   * Copy and transform the summary file, given the old and new
   * parameters in the mount structures.
   */
  STATIC int				/* error */
  xfs_rtcopy_summary(
  	xfs_mount_t	*omp,		/* old file system mount point */
  	xfs_mount_t	*nmp,		/* new file system mount point */
  	xfs_trans_t	*tp)		/* transaction pointer */
  {
  	xfs_rtblock_t	bbno;		/* bitmap block number */
  	xfs_buf_t	*bp;		/* summary buffer */
  	int		error;		/* error return value */
  	int		log;		/* summary level number (log length) */
  	xfs_suminfo_t	sum;		/* summary data */
  	xfs_fsblock_t	sumbno;		/* summary block number */
  
  	bp = NULL;
  	for (log = omp->m_rsumlevels - 1; log >= 0; log--) {
  		for (bbno = omp->m_sb.sb_rbmblocks - 1;
  		     (xfs_srtblock_t)bbno >= 0;
  		     bbno--) {
  			error = xfs_rtget_summary(omp, tp, log, bbno, &bp,
  				&sumbno, &sum);
  			if (error)
  				return error;
  			if (sum == 0)
  				continue;
  			error = xfs_rtmodify_summary(omp, tp, log, bbno, -sum,
  				&bp, &sumbno);
  			if (error)
  				return error;
  			error = xfs_rtmodify_summary(nmp, tp, log, bbno, sum,
  				&bp, &sumbno);
  			if (error)
  				return error;
  			ASSERT(sum > 0);
  		}
  	}
  	return 0;
  }
  
  /*
   * Searching backward from start to limit, find the first block whose
   * allocated/free state is different from start's.
   */
  STATIC int				/* error */
  xfs_rtfind_back(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	start,		/* starting block to look at */
  	xfs_rtblock_t	limit,		/* last block to look at */
  	xfs_rtblock_t	*rtblock)	/* out: start block found */
  {
  	xfs_rtword_t	*b;		/* current word in buffer */
  	int		bit;		/* bit number in the word */
  	xfs_rtblock_t	block;		/* bitmap block number */
  	xfs_buf_t	*bp;		/* buf for the block */
  	xfs_rtword_t	*bufp;		/* starting word in buffer */
  	int		error;		/* error value */
  	xfs_rtblock_t	firstbit;	/* first useful bit in the word */
  	xfs_rtblock_t	i;		/* current bit number rel. to start */
  	xfs_rtblock_t	len;		/* length of inspected area */
  	xfs_rtword_t	mask;		/* mask of relevant bits for value */
  	xfs_rtword_t	want;		/* mask for "good" values */
  	xfs_rtword_t	wdiff;		/* difference from wanted value */
  	int		word;		/* word number in the buffer */
  
  	/*
  	 * Compute and read in starting bitmap block for starting block.
  	 */
  	block = XFS_BITTOBLOCK(mp, start);
  	error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
  	if (error) {
  		return error;
  	}

  	bufp = bp->b_addr;

  	/*
  	 * Get the first word's index & point to it.
  	 */
  	word = XFS_BITTOWORD(mp, start);
  	b = &bufp[word];
  	bit = (int)(start & (XFS_NBWORD - 1));
  	len = start - limit + 1;
  	/*
  	 * Compute match value, based on the bit at start: if 1 (free)
  	 * then all-ones, else all-zeroes.
  	 */
  	want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
  	/*
  	 * If the starting position is not word-aligned, deal with the
  	 * partial word.
  	 */
  	if (bit < XFS_NBWORD - 1) {
  		/*
  		 * Calculate first (leftmost) bit number to look at,
  		 * and mask for all the relevant bits in this word.
  		 */
  		firstbit = XFS_RTMAX((xfs_srtblock_t)(bit - len + 1), 0);
  		mask = (((xfs_rtword_t)1 << (bit - firstbit + 1)) - 1) <<
  			firstbit;
  		/*
  		 * Calculate the difference between the value there
  		 * and what we're looking for.
  		 */
  		if ((wdiff = (*b ^ want) & mask)) {
  			/*
  			 * Different.  Mark where we are and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i = bit - XFS_RTHIBIT(wdiff);
  			*rtblock = start - i + 1;
  			return 0;
  		}
  		i = bit - firstbit + 1;
  		/*
  		 * Go on to previous block if that's where the previous word is
  		 * and we need the previous word.
  		 */
  		if (--word == -1 && i < len) {
  			/*
  			 * If done with this block, get the previous one.
  			 */
  			xfs_trans_brelse(tp, bp);
  			error = xfs_rtbuf_get(mp, tp, --block, 0, &bp);
  			if (error) {
  				return error;
  			}

  			bufp = bp->b_addr;

  			word = XFS_BLOCKWMASK(mp);
  			b = &bufp[word];
  		} else {
  			/*
  			 * Go on to the previous word in the buffer.
  			 */
  			b--;
  		}
  	} else {
  		/*
  		 * Starting on a word boundary, no partial word.
  		 */
  		i = 0;
  	}
  	/*
  	 * Loop over whole words in buffers.  When we use up one buffer
  	 * we move on to the previous one.
  	 */
  	while (len - i >= XFS_NBWORD) {
  		/*
  		 * Compute difference between actual and desired value.
  		 */
  		if ((wdiff = *b ^ want)) {
  			/*
  			 * Different, mark where we are and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i += XFS_NBWORD - 1 - XFS_RTHIBIT(wdiff);
  			*rtblock = start - i + 1;
  			return 0;
  		}
  		i += XFS_NBWORD;
  		/*
  		 * Go on to previous block if that's where the previous word is
  		 * and we need the previous word.
  		 */
  		if (--word == -1 && i < len) {
  			/*
  			 * If done with this block, get the previous one.
  			 */
  			xfs_trans_brelse(tp, bp);
  			error = xfs_rtbuf_get(mp, tp, --block, 0, &bp);
  			if (error) {
  				return error;
  			}

  			bufp = bp->b_addr;

  			word = XFS_BLOCKWMASK(mp);
  			b = &bufp[word];
  		} else {
  			/*
  			 * Go on to the previous word in the buffer.
  			 */
  			b--;
  		}
  	}
  	/*
  	 * If not ending on a word boundary, deal with the last
  	 * (partial) word.
  	 */
  	if (len - i) {
  		/*
  		 * Calculate first (leftmost) bit number to look at,
  		 * and mask for all the relevant bits in this word.
  		 */
  		firstbit = XFS_NBWORD - (len - i);
  		mask = (((xfs_rtword_t)1 << (len - i)) - 1) << firstbit;
  		/*
  		 * Compute difference between actual and desired value.
  		 */
  		if ((wdiff = (*b ^ want) & mask)) {
  			/*
  			 * Different, mark where we are and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i += XFS_NBWORD - 1 - XFS_RTHIBIT(wdiff);
  			*rtblock = start - i + 1;
  			return 0;
  		} else
  			i = len;
  	}
  	/*
  	 * No match, return that we scanned the whole area.
  	 */
  	xfs_trans_brelse(tp, bp);
  	*rtblock = start - i + 1;
  	return 0;
  }
  
  /*
   * Searching forward from start to limit, find the first block whose
   * allocated/free state is different from start's.
   */
  STATIC int				/* error */
  xfs_rtfind_forw(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	start,		/* starting block to look at */
  	xfs_rtblock_t	limit,		/* last block to look at */
  	xfs_rtblock_t	*rtblock)	/* out: start block found */
  {
  	xfs_rtword_t	*b;		/* current word in buffer */
  	int		bit;		/* bit number in the word */
  	xfs_rtblock_t	block;		/* bitmap block number */
  	xfs_buf_t	*bp;		/* buf for the block */
  	xfs_rtword_t	*bufp;		/* starting word in buffer */
  	int		error;		/* error value */
  	xfs_rtblock_t	i;		/* current bit number rel. to start */
  	xfs_rtblock_t	lastbit;	/* last useful bit in the word */
  	xfs_rtblock_t	len;		/* length of inspected area */
  	xfs_rtword_t	mask;		/* mask of relevant bits for value */
  	xfs_rtword_t	want;		/* mask for "good" values */
  	xfs_rtword_t	wdiff;		/* difference from wanted value */
  	int		word;		/* word number in the buffer */
  
  	/*
  	 * Compute and read in starting bitmap block for starting block.
  	 */
  	block = XFS_BITTOBLOCK(mp, start);
  	error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
  	if (error) {
  		return error;
  	}

  	bufp = bp->b_addr;

  	/*
  	 * Get the first word's index & point to it.
  	 */
  	word = XFS_BITTOWORD(mp, start);
  	b = &bufp[word];
  	bit = (int)(start & (XFS_NBWORD - 1));
  	len = limit - start + 1;
  	/*
  	 * Compute match value, based on the bit at start: if 1 (free)
  	 * then all-ones, else all-zeroes.
  	 */
  	want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
  	/*
  	 * If the starting position is not word-aligned, deal with the
  	 * partial word.
  	 */
  	if (bit) {
  		/*
  		 * Calculate last (rightmost) bit number to look at,
  		 * and mask for all the relevant bits in this word.
  		 */
  		lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
  		mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
  		/*
  		 * Calculate the difference between the value there
  		 * and what we're looking for.
  		 */
  		if ((wdiff = (*b ^ want) & mask)) {
  			/*
  			 * Different.  Mark where we are and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i = XFS_RTLOBIT(wdiff) - bit;
  			*rtblock = start + i - 1;
  			return 0;
  		}
  		i = lastbit - bit;
  		/*
  		 * Go on to next block if that's where the next word is
  		 * and we need the next word.
  		 */
  		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
  			/*
  			 * If done with this block, get the previous one.
  			 */
  			xfs_trans_brelse(tp, bp);
  			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
  			if (error) {
  				return error;
  			}

  			b = bufp = bp->b_addr;

  			word = 0;
  		} else {
  			/*
  			 * Go on to the previous word in the buffer.
  			 */
  			b++;
  		}
  	} else {
  		/*
  		 * Starting on a word boundary, no partial word.
  		 */
  		i = 0;
  	}
  	/*
  	 * Loop over whole words in buffers.  When we use up one buffer
  	 * we move on to the next one.
  	 */
  	while (len - i >= XFS_NBWORD) {
  		/*
  		 * Compute difference between actual and desired value.
  		 */
  		if ((wdiff = *b ^ want)) {
  			/*
  			 * Different, mark where we are and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i += XFS_RTLOBIT(wdiff);
  			*rtblock = start + i - 1;
  			return 0;
  		}
  		i += XFS_NBWORD;
  		/*
  		 * Go on to next block if that's where the next word is
  		 * and we need the next word.
  		 */
  		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
  			/*
  			 * If done with this block, get the next one.
  			 */
  			xfs_trans_brelse(tp, bp);
  			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
  			if (error) {
  				return error;
  			}

  			b = bufp = bp->b_addr;

  			word = 0;
  		} else {
  			/*
  			 * Go on to the next word in the buffer.
  			 */
  			b++;
  		}
  	}
  	/*
  	 * If not ending on a word boundary, deal with the last
  	 * (partial) word.
  	 */
  	if ((lastbit = len - i)) {
  		/*
  		 * Calculate mask for all the relevant bits in this word.
  		 */
  		mask = ((xfs_rtword_t)1 << lastbit) - 1;
  		/*
  		 * Compute difference between actual and desired value.
  		 */
  		if ((wdiff = (*b ^ want) & mask)) {
  			/*
  			 * Different, mark where we are and return.
  			 */
  			xfs_trans_brelse(tp, bp);
  			i += XFS_RTLOBIT(wdiff);
  			*rtblock = start + i - 1;
  			return 0;
  		} else
  			i = len;
  	}
  	/*
  	 * No match, return that we scanned the whole area.
  	 */
  	xfs_trans_brelse(tp, bp);
  	*rtblock = start + i - 1;
  	return 0;
  }
  
  /*
   * Mark an extent specified by start and len freed.
   * Updates all the summary information as well as the bitmap.
   */
  STATIC int				/* error */
  xfs_rtfree_range(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	start,		/* starting block to free */
  	xfs_extlen_t	len,		/* length to free */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb)		/* in/out: summary block number */
  {
  	xfs_rtblock_t	end;		/* end of the freed extent */
  	int		error;		/* error value */
  	xfs_rtblock_t	postblock;	/* first block freed > end */
  	xfs_rtblock_t	preblock;	/* first block freed < start */
  
  	end = start + len - 1;
  	/*
  	 * Modify the bitmap to mark this extent freed.
  	 */
  	error = xfs_rtmodify_range(mp, tp, start, len, 1);
  	if (error) {
  		return error;
  	}
  	/*
  	 * Assume we're freeing out of the middle of an allocated extent.
  	 * We need to find the beginning and end of the extent so we can
  	 * properly update the summary.
  	 */
  	error = xfs_rtfind_back(mp, tp, start, 0, &preblock);
  	if (error) {
  		return error;
  	}
  	/*
  	 * Find the next allocated block (end of allocated extent).
  	 */
  	error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
  		&postblock);

  	if (error)
  		return error;

  	/*
  	 * If there are blocks not being freed at the front of the
  	 * old extent, add summary data for them to be allocated.
  	 */
  	if (preblock < start) {
  		error = xfs_rtmodify_summary(mp, tp,
  			XFS_RTBLOCKLOG(start - preblock),
  			XFS_BITTOBLOCK(mp, preblock), -1, rbpp, rsb);
  		if (error) {
  			return error;
  		}
  	}
  	/*
  	 * If there are blocks not being freed at the end of the
  	 * old extent, add summary data for them to be allocated.
  	 */
  	if (postblock > end) {
  		error = xfs_rtmodify_summary(mp, tp,
  			XFS_RTBLOCKLOG(postblock - end),
  			XFS_BITTOBLOCK(mp, end + 1), -1, rbpp, rsb);
  		if (error) {
  			return error;
  		}
  	}
  	/*
  	 * Increment the summary information corresponding to the entire
  	 * (new) free extent.
  	 */
  	error = xfs_rtmodify_summary(mp, tp,
  		XFS_RTBLOCKLOG(postblock + 1 - preblock),
  		XFS_BITTOBLOCK(mp, preblock), 1, rbpp, rsb);
  	return error;
  }
  
  /*
   * Read and return the summary information for a given extent size,
   * bitmap block combination.
   * Keeps track of a current summary block, so we don't keep reading
   * it from the buffer cache.
   */
  STATIC int				/* error */
  xfs_rtget_summary(
  	xfs_mount_t	*mp,		/* file system mount structure */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	int		log,		/* log2 of extent size */
  	xfs_rtblock_t	bbno,		/* bitmap block number */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
  	xfs_suminfo_t	*sum)		/* out: summary info for this block */
  {
  	xfs_buf_t	*bp;		/* buffer for summary block */
  	int		error;		/* error value */
  	xfs_fsblock_t	sb;		/* summary fsblock */
  	int		so;		/* index into the summary file */
  	xfs_suminfo_t	*sp;		/* pointer to returned data */
  
  	/*
  	 * Compute entry number in the summary file.
  	 */
  	so = XFS_SUMOFFS(mp, log, bbno);
  	/*
  	 * Compute the block number in the summary file.
  	 */
  	sb = XFS_SUMOFFSTOBLOCK(mp, so);
  	/*
  	 * If we have an old buffer, and the block number matches, use that.
  	 */
  	if (rbpp && *rbpp && *rsb == sb)
  		bp = *rbpp;
  	/*
  	 * Otherwise we have to get the buffer.
  	 */
  	else {
  		/*
  		 * If there was an old one, get rid of it first.
  		 */
  		if (rbpp && *rbpp)
  			xfs_trans_brelse(tp, *rbpp);
  		error = xfs_rtbuf_get(mp, tp, sb, 1, &bp);
  		if (error) {
  			return error;
  		}
  		/*
  		 * Remember this buffer and block for the next call.
  		 */
  		if (rbpp) {
  			*rbpp = bp;
  			*rsb = sb;
  		}
  	}
  	/*
  	 * Point to the summary information & copy it out.
  	 */
  	sp = XFS_SUMPTR(mp, bp, so);
  	*sum = *sp;
  	/*
  	 * Drop the buffer if we're not asked to remember it.
  	 */
  	if (!rbpp)
  		xfs_trans_brelse(tp, bp);
  	return 0;
  }
  
  /*
   * Set the given range of bitmap bits to the given value.
   * Do whatever I/O and logging is required.
   */
  STATIC int				/* error */
  xfs_rtmodify_range(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	start,		/* starting block to modify */
  	xfs_extlen_t	len,		/* length of extent to modify */
  	int		val)		/* 1 for free, 0 for allocated */
  {
  	xfs_rtword_t	*b;		/* current word in buffer */
  	int		bit;		/* bit number in the word */
  	xfs_rtblock_t	block;		/* bitmap block number */
  	xfs_buf_t	*bp;		/* buf for the block */
  	xfs_rtword_t	*bufp;		/* starting word in buffer */
  	int		error;		/* error value */
  	xfs_rtword_t	*first;		/* first used word in the buffer */
  	int		i;		/* current bit number rel. to start */
  	int		lastbit;	/* last useful bit in word */
  	xfs_rtword_t	mask;		/* mask o frelevant bits for value */
  	int		word;		/* word number in the buffer */
  
  	/*
  	 * Compute starting bitmap block number.
  	 */
  	block = XFS_BITTOBLOCK(mp, start);
  	/*
  	 * Read the bitmap block, and point to its data.
  	 */
  	error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
  	if (error) {
  		return error;
  	}

  	bufp = bp->b_addr;

  	/*
  	 * Compute the starting word's address, and starting bit.
  	 */
  	word = XFS_BITTOWORD(mp, start);
  	first = b = &bufp[word];
  	bit = (int)(start & (XFS_NBWORD - 1));
  	/*
  	 * 0 (allocated) => all zeroes; 1 (free) => all ones.
  	 */
  	val = -val;
  	/*
  	 * If not starting on a word boundary, deal with the first
  	 * (partial) word.
  	 */
  	if (bit) {
  		/*
  		 * Compute first bit not changed and mask of relevant bits.
  		 */
  		lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
  		mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
  		/*
  		 * Set/clear the active bits.
  		 */
  		if (val)
  			*b |= mask;
  		else
  			*b &= ~mask;
  		i = lastbit - bit;
  		/*
  		 * Go on to the next block if that's where the next word is
  		 * and we need the next word.
  		 */
  		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
  			/*
  			 * Log the changed part of this block.
  			 * Get the next one.
  			 */
  			xfs_trans_log_buf(tp, bp,
  				(uint)((char *)first - (char *)bufp),
  				(uint)((char *)b - (char *)bufp));
  			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
  			if (error) {
  				return error;
  			}

  			first = b = bufp = bp->b_addr;

  			word = 0;
  		} else {
  			/*
  			 * Go on to the next word in the buffer
  			 */
  			b++;
  		}
  	} else {
  		/*
  		 * Starting on a word boundary, no partial word.
  		 */
  		i = 0;
  	}
  	/*
  	 * Loop over whole words in buffers.  When we use up one buffer
  	 * we move on to the next one.
  	 */
  	while (len - i >= XFS_NBWORD) {
  		/*
  		 * Set the word value correctly.
  		 */
  		*b = val;
  		i += XFS_NBWORD;
  		/*
  		 * Go on to the next block if that's where the next word is
  		 * and we need the next word.
  		 */
  		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
  			/*
  			 * Log the changed part of this block.
  			 * Get the next one.
  			 */
  			xfs_trans_log_buf(tp, bp,
  				(uint)((char *)first - (char *)bufp),
  				(uint)((char *)b - (char *)bufp));
  			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
  			if (error) {
  				return error;
  			}

  			first = b = bufp = bp->b_addr;

  			word = 0;
  		} else {
  			/*
  			 * Go on to the next word in the buffer
  			 */
  			b++;
  		}
  	}
  	/*
  	 * If not ending on a word boundary, deal with the last
  	 * (partial) word.
  	 */
  	if ((lastbit = len - i)) {
  		/*
  		 * Compute a mask of relevant bits.
  		 */
  		bit = 0;
  		mask = ((xfs_rtword_t)1 << lastbit) - 1;
  		/*
  		 * Set/clear the active bits.
  		 */
  		if (val)
  			*b |= mask;
  		else
  			*b &= ~mask;
  		b++;
  	}
  	/*
  	 * Log any remaining changed bytes.
  	 */
  	if (b > first)
  		xfs_trans_log_buf(tp, bp, (uint)((char *)first - (char *)bufp),
  			(uint)((char *)b - (char *)bufp - 1));
  	return 0;
  }
  
  /*
   * Read and modify the summary information for a given extent size,
   * bitmap block combination.
   * Keeps track of a current summary block, so we don't keep reading
   * it from the buffer cache.
   */
  STATIC int				/* error */
  xfs_rtmodify_summary(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	int		log,		/* log2 of extent size */
  	xfs_rtblock_t	bbno,		/* bitmap block number */
  	int		delta,		/* change to make to summary info */
  	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
  	xfs_fsblock_t	*rsb)		/* in/out: summary block number */
  {
  	xfs_buf_t	*bp;		/* buffer for the summary block */
  	int		error;		/* error value */
  	xfs_fsblock_t	sb;		/* summary fsblock */
  	int		so;		/* index into the summary file */
  	xfs_suminfo_t	*sp;		/* pointer to returned data */
  
  	/*
  	 * Compute entry number in the summary file.
  	 */
  	so = XFS_SUMOFFS(mp, log, bbno);
  	/*
  	 * Compute the block number in the summary file.
  	 */
  	sb = XFS_SUMOFFSTOBLOCK(mp, so);
  	/*
  	 * If we have an old buffer, and the block number matches, use that.
  	 */
  	if (rbpp && *rbpp && *rsb == sb)
  		bp = *rbpp;
  	/*
  	 * Otherwise we have to get the buffer.
  	 */
  	else {
  		/*
  		 * If there was an old one, get rid of it first.
  		 */
  		if (rbpp && *rbpp)
  			xfs_trans_brelse(tp, *rbpp);
  		error = xfs_rtbuf_get(mp, tp, sb, 1, &bp);
  		if (error) {
  			return error;
  		}
  		/*
  		 * Remember this buffer and block for the next call.
  		 */
  		if (rbpp) {
  			*rbpp = bp;
  			*rsb = sb;
  		}
  	}
  	/*
  	 * Point to the summary information, modify and log it.
  	 */
  	sp = XFS_SUMPTR(mp, bp, so);
  	*sp += delta;

  	xfs_trans_log_buf(tp, bp, (uint)((char *)sp - (char *)bp->b_addr),
  		(uint)((char *)sp - (char *)bp->b_addr + sizeof(*sp) - 1));

  	return 0;
  }
  
  /*
   * Visible (exported) functions.
   */
  
  /*
   * Grow the realtime area of the filesystem.
   */
  int
  xfs_growfs_rt(
  	xfs_mount_t	*mp,		/* mount point for filesystem */
  	xfs_growfs_rt_t	*in)		/* growfs rt input struct */
  {
  	xfs_rtblock_t	bmbno;		/* bitmap block number */
  	xfs_buf_t	*bp;		/* temporary buffer */

  	int		error;		/* error return value */

  	xfs_mount_t	*nmp;		/* new (fake) mount structure */
  	xfs_drfsbno_t	nrblocks;	/* new number of realtime blocks */
  	xfs_extlen_t	nrbmblocks;	/* new number of rt bitmap blocks */
  	xfs_drtbno_t	nrextents;	/* new number of realtime extents */
  	uint8_t		nrextslog;	/* new log2 of sb_rextents */
  	xfs_extlen_t	nrsumblocks;	/* new number of summary blocks */
  	uint		nrsumlevels;	/* new rt summary levels */
  	uint		nrsumsize;	/* new size of rt summary, bytes */
  	xfs_sb_t	*nsbp;		/* new superblock */
  	xfs_extlen_t	rbmblocks;	/* current number of rt bitmap blocks */
  	xfs_extlen_t	rsumblocks;	/* current number of rt summary blks */
  	xfs_sb_t	*sbp;		/* old superblock */
  	xfs_fsblock_t	sumbno;		/* summary block number */

  
  	sbp = &mp->m_sb;
  	/*
  	 * Initial error checking.
  	 */

  	if (!capable(CAP_SYS_ADMIN))
  		return XFS_ERROR(EPERM);

  	if (mp->m_rtdev_targp == NULL || mp->m_rbmip == NULL ||

  	    (nrblocks = in->newblocks) <= sbp->sb_rblocks ||
  	    (sbp->sb_rblocks && (in->extsize != sbp->sb_rextsize)))
  		return XFS_ERROR(EINVAL);

  	if ((error = xfs_sb_validate_fsb_count(sbp, nrblocks)))
  		return error;

  	/*
  	 * Read in the last block of the device, make sure it exists.
  	 */

  	bp = xfs_buf_read_uncached(mp, mp->m_rtdev_targp,
  				XFS_FSB_TO_BB(mp, nrblocks - 1),
  				XFS_FSB_TO_B(mp, 1), 0);
  	if (!bp)
  		return EIO;

  	xfs_buf_relse(bp);

  	/*
  	 * Calculate new parameters.  These are the final values to be reached.
  	 */
  	nrextents = nrblocks;
  	do_div(nrextents, in->extsize);

  	nrbmblocks = howmany_64(nrextents, NBBY * sbp->sb_blocksize);

  	nrextslog = xfs_highbit32(nrextents);
  	nrsumlevels = nrextslog + 1;
  	nrsumsize = (uint)sizeof(xfs_suminfo_t) * nrsumlevels * nrbmblocks;
  	nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
  	nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
  	/*
  	 * New summary size can't be more than half the size of
  	 * the log.  This prevents us from getting a log overflow,
  	 * since we'll log basically the whole summary file at once.
  	 */
  	if (nrsumblocks > (mp->m_sb.sb_logblocks >> 1))
  		return XFS_ERROR(EINVAL);
  	/*
  	 * Get the old block counts for bitmap and summary inodes.
  	 * These can't change since other growfs callers are locked out.
  	 */
  	rbmblocks = XFS_B_TO_FSB(mp, mp->m_rbmip->i_d.di_size);
  	rsumblocks = XFS_B_TO_FSB(mp, mp->m_rsumip->i_d.di_size);
  	/*
  	 * Allocate space to the bitmap and summary files, as necessary.
  	 */

  	error = xfs_growfs_rt_alloc(mp, rbmblocks, nrbmblocks, mp->m_rbmip);
  	if (error)

  		return error;

  	error = xfs_growfs_rt_alloc(mp, rsumblocks, nrsumblocks, mp->m_rsumip);
  	if (error)

  		return error;

  	/*
  	 * Allocate a new (fake) mount/sb.
  	 */
  	nmp = kmem_alloc(sizeof(*nmp), KM_SLEEP);

  	/*
  	 * Loop over the bitmap blocks.
  	 * We will do everything one bitmap block at a time.
  	 * Skip the current block if it is exactly full.
  	 * This also deals with the case where there were no rtextents before.
  	 */
  	for (bmbno = sbp->sb_rbmblocks -
  		     ((sbp->sb_rextents & ((1 << mp->m_blkbit_log) - 1)) != 0);
  	     bmbno < nrbmblocks;
  	     bmbno++) {

  		xfs_trans_t	*tp;
  		int		cancelflags = 0;

  		*nmp = *mp;
  		nsbp = &nmp->m_sb;
  		/*
  		 * Calculate new sb and mount fields for this round.
  		 */
  		nsbp->sb_rextsize = in->extsize;
  		nsbp->sb_rbmblocks = bmbno + 1;
  		nsbp->sb_rblocks =
  			XFS_RTMIN(nrblocks,
  				  nsbp->sb_rbmblocks * NBBY *
  				  nsbp->sb_blocksize * nsbp->sb_rextsize);
  		nsbp->sb_rextents = nsbp->sb_rblocks;
  		do_div(nsbp->sb_rextents, nsbp->sb_rextsize);

  		ASSERT(nsbp->sb_rextents != 0);

  		nsbp->sb_rextslog = xfs_highbit32(nsbp->sb_rextents);
  		nrsumlevels = nmp->m_rsumlevels = nsbp->sb_rextslog + 1;
  		nrsumsize =
  			(uint)sizeof(xfs_suminfo_t) * nrsumlevels *
  			nsbp->sb_rbmblocks;
  		nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
  		nmp->m_rsumsize = nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
  		/*
  		 * Start a transaction, get the log reservation.
  		 */
  		tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFSRT_FREE);

  		if ((error = xfs_trans_reserve(tp, 0,
  				XFS_GROWRTFREE_LOG_RES(nmp), 0, 0, 0)))

  			goto error_cancel;

  		/*
  		 * Lock out other callers by grabbing the bitmap inode lock.
  		 */

  		xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL);

  		xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);

  		/*
  		 * Update the bitmap inode's size.
  		 */
  		mp->m_rbmip->i_d.di_size =
  			nsbp->sb_rbmblocks * nsbp->sb_blocksize;
  		xfs_trans_log_inode(tp, mp->m_rbmip, XFS_ILOG_CORE);
  		cancelflags |= XFS_TRANS_ABORT;
  		/*
  		 * Get the summary inode into the transaction.
  		 */

  		xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL);

  		xfs_trans_ijoin(tp, mp->m_rsumip, XFS_ILOCK_EXCL);

  		/*
  		 * Update the summary inode's size.
  		 */
  		mp->m_rsumip->i_d.di_size = nmp->m_rsumsize;
  		xfs_trans_log_inode(tp, mp->m_rsumip, XFS_ILOG_CORE);
  		/*
  		 * Copy summary data from old to new sizes.
  		 * Do this when the real size (not block-aligned) changes.
  		 */
  		if (sbp->sb_rbmblocks != nsbp->sb_rbmblocks ||
  		    mp->m_rsumlevels != nmp->m_rsumlevels) {
  			error = xfs_rtcopy_summary(mp, nmp, tp);
  			if (error)

  				goto error_cancel;

  		}
  		/*
  		 * Update superblock fields.
  		 */
  		if (nsbp->sb_rextsize != sbp->sb_rextsize)
  			xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSIZE,
  				nsbp->sb_rextsize - sbp->sb_rextsize);
  		if (nsbp->sb_rbmblocks != sbp->sb_rbmblocks)
  			xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBMBLOCKS,
  				nsbp->sb_rbmblocks - sbp->sb_rbmblocks);
  		if (nsbp->sb_rblocks != sbp->sb_rblocks)
  			xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBLOCKS,
  				nsbp->sb_rblocks - sbp->sb_rblocks);
  		if (nsbp->sb_rextents != sbp->sb_rextents)
  			xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTENTS,
  				nsbp->sb_rextents - sbp->sb_rextents);
  		if (nsbp->sb_rextslog != sbp->sb_rextslog)
  			xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSLOG,
  				nsbp->sb_rextslog - sbp->sb_rextslog);
  		/*
  		 * Free new extent.
  		 */
  		bp = NULL;
  		error = xfs_rtfree_range(nmp, tp, sbp->sb_rextents,
  			nsbp->sb_rextents - sbp->sb_rextents, &bp, &sumbno);

  		if (error) {
  error_cancel:
  			xfs_trans_cancel(tp, cancelflags);

  			break;

  		}

  		/*
  		 * Mark more blocks free in the superblock.
  		 */
  		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS,
  			nsbp->sb_rextents - sbp->sb_rextents);
  		/*

  		 * Update mp values into the real mp structure.
  		 */
  		mp->m_rsumlevels = nrsumlevels;
  		mp->m_rsumsize = nrsumsize;

  
  		error = xfs_trans_commit(tp, 0);

  		if (error)

  			break;

  	}

  	/*

  	 * Free the fake mp structure.

  	 */

  	kmem_free(nmp);

  	return error;
  }
  
  /*
   * Allocate an extent in the realtime subvolume, with the usual allocation
   * parameters.  The length units are all in realtime extents, as is the
   * result block number.
   */
  int					/* error */
  xfs_rtallocate_extent(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	bno,		/* starting block number to allocate */
  	xfs_extlen_t	minlen,		/* minimum length to allocate */
  	xfs_extlen_t	maxlen,		/* maximum length to allocate */
  	xfs_extlen_t	*len,		/* out: actual length allocated */
  	xfs_alloctype_t	type,		/* allocation type XFS_ALLOCTYPE... */
  	int		wasdel,		/* was a delayed allocation extent */
  	xfs_extlen_t	prod,		/* extent product factor */
  	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
  {

  	xfs_mount_t	*mp = tp->t_mountp;

  	int		error;		/* error value */

  	xfs_rtblock_t	r;		/* result allocated block */
  	xfs_fsblock_t	sb;		/* summary file block number */
  	xfs_buf_t	*sumbp;		/* summary file block buffer */

  	ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));

  	ASSERT(minlen > 0 && minlen <= maxlen);

  	/*
  	 * If prod is set then figure out what to do to minlen and maxlen.
  	 */
  	if (prod > 1) {
  		xfs_extlen_t	i;
  
  		if ((i = maxlen % prod))
  			maxlen -= i;
  		if ((i = minlen % prod))
  			minlen += prod - i;
  		if (maxlen < minlen) {
  			*rtblock = NULLRTBLOCK;
  			return 0;
  		}
  	}

  	sumbp = NULL;
  	/*
  	 * Allocate by size, or near another block, or exactly at some block.
  	 */
  	switch (type) {
  	case XFS_ALLOCTYPE_ANY_AG:
  		error = xfs_rtallocate_extent_size(mp, tp, minlen, maxlen, len,
  				&sumbp,	&sb, prod, &r);
  		break;
  	case XFS_ALLOCTYPE_NEAR_BNO:
  		error = xfs_rtallocate_extent_near(mp, tp, bno, minlen, maxlen,
  				len, &sumbp, &sb, prod, &r);
  		break;
  	case XFS_ALLOCTYPE_THIS_BNO:
  		error = xfs_rtallocate_extent_exact(mp, tp, bno, minlen, maxlen,
  				len, &sumbp, &sb, prod, &r);
  		break;
  	default:

  		error = EIO;

  		ASSERT(0);
  	}

  	if (error)

  		return error;

  	/*
  	 * If it worked, update the superblock.
  	 */
  	if (r != NULLRTBLOCK) {
  		long	slen = (long)*len;
  
  		ASSERT(*len >= minlen && *len <= maxlen);
  		if (wasdel)
  			xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FREXTENTS, -slen);
  		else
  			xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS, -slen);
  	}
  	*rtblock = r;
  	return 0;
  }
  
  /*
   * Free an extent in the realtime subvolume.  Length is expressed in
   * realtime extents, as is the block number.
   */
  int					/* error */
  xfs_rtfree_extent(
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_rtblock_t	bno,		/* starting block number to free */
  	xfs_extlen_t	len)		/* length of extent freed */
  {
  	int		error;		/* error value */

  	xfs_mount_t	*mp;		/* file system mount structure */
  	xfs_fsblock_t	sb;		/* summary file block number */
  	xfs_buf_t	*sumbp;		/* summary file block buffer */
  
  	mp = tp->t_mountp;
  	/*
  	 * Synchronize by locking the bitmap inode.
  	 */

  	xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL);

  	xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);

  #if defined(__KERNEL__) && defined(DEBUG)
  	/*
  	 * Check to see that this whole range is currently allocated.
  	 */
  	{
  		int	stat;		/* result from checking range */
  
  		error = xfs_rtcheck_alloc_range(mp, tp, bno, len, &stat);
  		if (error) {
  			return error;
  		}
  		ASSERT(stat);
  	}
  #endif
  	sumbp = NULL;
  	/*
  	 * Free the range of realtime blocks.
  	 */
  	error = xfs_rtfree_range(mp, tp, bno, len, &sumbp, &sb);
  	if (error) {
  		return error;
  	}
  	/*
  	 * Mark more blocks free in the superblock.
  	 */
  	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS, (long)len);
  	/*
  	 * If we've now freed all the blocks, reset the file sequence
  	 * number to 0.
  	 */
  	if (tp->t_frextents_delta + mp->m_sb.sb_frextents ==
  	    mp->m_sb.sb_rextents) {

  		if (!(mp->m_rbmip->i_d.di_flags & XFS_DIFLAG_NEWRTBM))
  			mp->m_rbmip->i_d.di_flags |= XFS_DIFLAG_NEWRTBM;
  		*(__uint64_t *)&mp->m_rbmip->i_d.di_atime = 0;
  		xfs_trans_log_inode(tp, mp->m_rbmip, XFS_ILOG_CORE);

  	}
  	return 0;
  }
  
  /*
   * Initialize realtime fields in the mount structure.
   */
  int				/* error */
  xfs_rtmount_init(
  	xfs_mount_t	*mp)	/* file system mount structure */
  {
  	xfs_buf_t	*bp;	/* buffer for last block of subvolume */
  	xfs_daddr_t	d;	/* address of last block of subvolume */

  	xfs_sb_t	*sbp;	/* filesystem superblock copy in mount */
  
  	sbp = &mp->m_sb;
  	if (sbp->sb_rblocks == 0)
  		return 0;
  	if (mp->m_rtdev_targp == NULL) {

  		xfs_warn(mp,
  	"Filesystem has a realtime volume, use rtdev=device option");

  		return XFS_ERROR(ENODEV);
  	}
  	mp->m_rsumlevels = sbp->sb_rextslog + 1;
  	mp->m_rsumsize =
  		(uint)sizeof(xfs_suminfo_t) * mp->m_rsumlevels *
  		sbp->sb_rbmblocks;
  	mp->m_rsumsize = roundup(mp->m_rsumsize, sbp->sb_blocksize);
  	mp->m_rbmip = mp->m_rsumip = NULL;
  	/*
  	 * Check that the realtime section is an ok size.
  	 */
  	d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_rblocks);
  	if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_rblocks) {

  		xfs_warn(mp, "realtime mount -- %llu != %llu",

  			(unsigned long long) XFS_BB_TO_FSB(mp, d),
  			(unsigned long long) mp->m_sb.sb_rblocks);

  		return XFS_ERROR(EFBIG);

  	}

  	bp = xfs_buf_read_uncached(mp, mp->m_rtdev_targp,
  					d - XFS_FSB_TO_BB(mp, 1),
  					XFS_FSB_TO_B(mp, 1), 0);
  	if (!bp) {

  		xfs_warn(mp, "realtime device size check failed");

  		return EIO;

  	}
  	xfs_buf_relse(bp);
  	return 0;
  }
  
  /*
   * Get the bitmap and summary inodes into the mount structure
   * at mount time.
   */
  int					/* error */
  xfs_rtmount_inodes(
  	xfs_mount_t	*mp)		/* file system mount structure */
  {
  	int		error;		/* error return value */
  	xfs_sb_t	*sbp;
  
  	sbp = &mp->m_sb;
  	if (sbp->sb_rbmino == NULLFSINO)
  		return 0;

  	error = xfs_iget(mp, NULL, sbp->sb_rbmino, 0, 0, &mp->m_rbmip);

  	if (error)
  		return error;
  	ASSERT(mp->m_rbmip != NULL);
  	ASSERT(sbp->sb_rsumino != NULLFSINO);

  	error = xfs_iget(mp, NULL, sbp->sb_rsumino, 0, 0, &mp->m_rsumip);

  	if (error) {

  		IRELE(mp->m_rbmip);

  		return error;
  	}
  	ASSERT(mp->m_rsumip != NULL);
  	return 0;
  }

  void
  xfs_rtunmount_inodes(
  	struct xfs_mount	*mp)
  {
  	if (mp->m_rbmip)
  		IRELE(mp->m_rbmip);
  	if (mp->m_rsumip)
  		IRELE(mp->m_rsumip);
  }

  /*
   * Pick an extent for allocation at the start of a new realtime file.
   * Use the sequence number stored in the atime field of the bitmap inode.
   * Translate this to a fraction of the rtextents, and return the product
   * of rtextents and the fraction.
   * The fraction sequence is 0, 1/2, 1/4, 3/4, 1/8, ..., 7/8, 1/16, ...
   */
  int					/* error */
  xfs_rtpick_extent(
  	xfs_mount_t	*mp,		/* file system mount point */
  	xfs_trans_t	*tp,		/* transaction pointer */
  	xfs_extlen_t	len,		/* allocation length (rtextents) */
  	xfs_rtblock_t	*pick)		/* result rt extent */
  {
  	xfs_rtblock_t	b;		/* result block */

  	int		log2;		/* log of sequence number */
  	__uint64_t	resid;		/* residual after log removed */
  	__uint64_t	seq;		/* sequence number of file creation */
  	__uint64_t	*seqp;		/* pointer to seqno in inode */

  	ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));
  
  	seqp = (__uint64_t *)&mp->m_rbmip->i_d.di_atime;
  	if (!(mp->m_rbmip->i_d.di_flags & XFS_DIFLAG_NEWRTBM)) {
  		mp->m_rbmip->i_d.di_flags |= XFS_DIFLAG_NEWRTBM;

  		*seqp = 0;
  	}
  	seq = *seqp;
  	if ((log2 = xfs_highbit64(seq)) == -1)
  		b = 0;
  	else {
  		resid = seq - (1ULL << log2);
  		b = (mp->m_sb.sb_rextents * ((resid << 1) + 1ULL)) >>
  		    (log2 + 1);
  		if (b >= mp->m_sb.sb_rextents)
  			b = do_mod(b, mp->m_sb.sb_rextents);
  		if (b + len > mp->m_sb.sb_rextents)
  			b = mp->m_sb.sb_rextents - len;
  	}
  	*seqp = seq + 1;

  	xfs_trans_log_inode(tp, mp->m_rbmip, XFS_ILOG_CORE);

  	*pick = b;
  	return 0;
  }