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/fs/xfs/xfs_alloc.c

https://bitbucket.org/digetx/picasso-kernel
C | 2558 lines | 1782 code | 180 blank | 596 comment | 457 complexity | 644457ef9a0b9eea7f668a1148b5a7ae MD5 | raw file

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   1/*
   2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#include "xfs.h"
  19#include "xfs_fs.h"
  20#include "xfs_types.h"
  21#include "xfs_bit.h"
  22#include "xfs_log.h"
  23#include "xfs_trans.h"
  24#include "xfs_sb.h"
  25#include "xfs_ag.h"
  26#include "xfs_mount.h"
  27#include "xfs_bmap_btree.h"
  28#include "xfs_alloc_btree.h"
  29#include "xfs_ialloc_btree.h"
  30#include "xfs_dinode.h"
  31#include "xfs_inode.h"
  32#include "xfs_btree.h"
  33#include "xfs_alloc.h"
  34#include "xfs_extent_busy.h"
  35#include "xfs_error.h"
  36#include "xfs_trace.h"
  37
  38struct workqueue_struct *xfs_alloc_wq;
  39
  40#define XFS_ABSDIFF(a,b)	(((a) <= (b)) ? ((b) - (a)) : ((a) - (b)))
  41
  42#define	XFSA_FIXUP_BNO_OK	1
  43#define	XFSA_FIXUP_CNT_OK	2
  44
  45STATIC int xfs_alloc_ag_vextent_exact(xfs_alloc_arg_t *);
  46STATIC int xfs_alloc_ag_vextent_near(xfs_alloc_arg_t *);
  47STATIC int xfs_alloc_ag_vextent_size(xfs_alloc_arg_t *);
  48STATIC int xfs_alloc_ag_vextent_small(xfs_alloc_arg_t *,
  49		xfs_btree_cur_t *, xfs_agblock_t *, xfs_extlen_t *, int *);
  50
  51/*
  52 * Lookup the record equal to [bno, len] in the btree given by cur.
  53 */
  54STATIC int				/* error */
  55xfs_alloc_lookup_eq(
  56	struct xfs_btree_cur	*cur,	/* btree cursor */
  57	xfs_agblock_t		bno,	/* starting block of extent */
  58	xfs_extlen_t		len,	/* length of extent */
  59	int			*stat)	/* success/failure */
  60{
  61	cur->bc_rec.a.ar_startblock = bno;
  62	cur->bc_rec.a.ar_blockcount = len;
  63	return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
  64}
  65
  66/*
  67 * Lookup the first record greater than or equal to [bno, len]
  68 * in the btree given by cur.
  69 */
  70int				/* error */
  71xfs_alloc_lookup_ge(
  72	struct xfs_btree_cur	*cur,	/* btree cursor */
  73	xfs_agblock_t		bno,	/* starting block of extent */
  74	xfs_extlen_t		len,	/* length of extent */
  75	int			*stat)	/* success/failure */
  76{
  77	cur->bc_rec.a.ar_startblock = bno;
  78	cur->bc_rec.a.ar_blockcount = len;
  79	return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
  80}
  81
  82/*
  83 * Lookup the first record less than or equal to [bno, len]
  84 * in the btree given by cur.
  85 */
  86int					/* error */
  87xfs_alloc_lookup_le(
  88	struct xfs_btree_cur	*cur,	/* btree cursor */
  89	xfs_agblock_t		bno,	/* starting block of extent */
  90	xfs_extlen_t		len,	/* length of extent */
  91	int			*stat)	/* success/failure */
  92{
  93	cur->bc_rec.a.ar_startblock = bno;
  94	cur->bc_rec.a.ar_blockcount = len;
  95	return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
  96}
  97
  98/*
  99 * Update the record referred to by cur to the value given
 100 * by [bno, len].
 101 * This either works (return 0) or gets an EFSCORRUPTED error.
 102 */
 103STATIC int				/* error */
 104xfs_alloc_update(
 105	struct xfs_btree_cur	*cur,	/* btree cursor */
 106	xfs_agblock_t		bno,	/* starting block of extent */
 107	xfs_extlen_t		len)	/* length of extent */
 108{
 109	union xfs_btree_rec	rec;
 110
 111	rec.alloc.ar_startblock = cpu_to_be32(bno);
 112	rec.alloc.ar_blockcount = cpu_to_be32(len);
 113	return xfs_btree_update(cur, &rec);
 114}
 115
 116/*
 117 * Get the data from the pointed-to record.
 118 */
 119int					/* error */
 120xfs_alloc_get_rec(
 121	struct xfs_btree_cur	*cur,	/* btree cursor */
 122	xfs_agblock_t		*bno,	/* output: starting block of extent */
 123	xfs_extlen_t		*len,	/* output: length of extent */
 124	int			*stat)	/* output: success/failure */
 125{
 126	union xfs_btree_rec	*rec;
 127	int			error;
 128
 129	error = xfs_btree_get_rec(cur, &rec, stat);
 130	if (!error && *stat == 1) {
 131		*bno = be32_to_cpu(rec->alloc.ar_startblock);
 132		*len = be32_to_cpu(rec->alloc.ar_blockcount);
 133	}
 134	return error;
 135}
 136
 137/*
 138 * Compute aligned version of the found extent.
 139 * Takes alignment and min length into account.
 140 */
 141STATIC void
 142xfs_alloc_compute_aligned(
 143	xfs_alloc_arg_t	*args,		/* allocation argument structure */
 144	xfs_agblock_t	foundbno,	/* starting block in found extent */
 145	xfs_extlen_t	foundlen,	/* length in found extent */
 146	xfs_agblock_t	*resbno,	/* result block number */
 147	xfs_extlen_t	*reslen)	/* result length */
 148{
 149	xfs_agblock_t	bno;
 150	xfs_extlen_t	len;
 151
 152	/* Trim busy sections out of found extent */
 153	xfs_extent_busy_trim(args, foundbno, foundlen, &bno, &len);
 154
 155	if (args->alignment > 1 && len >= args->minlen) {
 156		xfs_agblock_t	aligned_bno = roundup(bno, args->alignment);
 157		xfs_extlen_t	diff = aligned_bno - bno;
 158
 159		*resbno = aligned_bno;
 160		*reslen = diff >= len ? 0 : len - diff;
 161	} else {
 162		*resbno = bno;
 163		*reslen = len;
 164	}
 165}
 166
 167/*
 168 * Compute best start block and diff for "near" allocations.
 169 * freelen >= wantlen already checked by caller.
 170 */
 171STATIC xfs_extlen_t			/* difference value (absolute) */
 172xfs_alloc_compute_diff(
 173	xfs_agblock_t	wantbno,	/* target starting block */
 174	xfs_extlen_t	wantlen,	/* target length */
 175	xfs_extlen_t	alignment,	/* target alignment */
 176	xfs_agblock_t	freebno,	/* freespace's starting block */
 177	xfs_extlen_t	freelen,	/* freespace's length */
 178	xfs_agblock_t	*newbnop)	/* result: best start block from free */
 179{
 180	xfs_agblock_t	freeend;	/* end of freespace extent */
 181	xfs_agblock_t	newbno1;	/* return block number */
 182	xfs_agblock_t	newbno2;	/* other new block number */
 183	xfs_extlen_t	newlen1=0;	/* length with newbno1 */
 184	xfs_extlen_t	newlen2=0;	/* length with newbno2 */
 185	xfs_agblock_t	wantend;	/* end of target extent */
 186
 187	ASSERT(freelen >= wantlen);
 188	freeend = freebno + freelen;
 189	wantend = wantbno + wantlen;
 190	if (freebno >= wantbno) {
 191		if ((newbno1 = roundup(freebno, alignment)) >= freeend)
 192			newbno1 = NULLAGBLOCK;
 193	} else if (freeend >= wantend && alignment > 1) {
 194		newbno1 = roundup(wantbno, alignment);
 195		newbno2 = newbno1 - alignment;
 196		if (newbno1 >= freeend)
 197			newbno1 = NULLAGBLOCK;
 198		else
 199			newlen1 = XFS_EXTLEN_MIN(wantlen, freeend - newbno1);
 200		if (newbno2 < freebno)
 201			newbno2 = NULLAGBLOCK;
 202		else
 203			newlen2 = XFS_EXTLEN_MIN(wantlen, freeend - newbno2);
 204		if (newbno1 != NULLAGBLOCK && newbno2 != NULLAGBLOCK) {
 205			if (newlen1 < newlen2 ||
 206			    (newlen1 == newlen2 &&
 207			     XFS_ABSDIFF(newbno1, wantbno) >
 208			     XFS_ABSDIFF(newbno2, wantbno)))
 209				newbno1 = newbno2;
 210		} else if (newbno2 != NULLAGBLOCK)
 211			newbno1 = newbno2;
 212	} else if (freeend >= wantend) {
 213		newbno1 = wantbno;
 214	} else if (alignment > 1) {
 215		newbno1 = roundup(freeend - wantlen, alignment);
 216		if (newbno1 > freeend - wantlen &&
 217		    newbno1 - alignment >= freebno)
 218			newbno1 -= alignment;
 219		else if (newbno1 >= freeend)
 220			newbno1 = NULLAGBLOCK;
 221	} else
 222		newbno1 = freeend - wantlen;
 223	*newbnop = newbno1;
 224	return newbno1 == NULLAGBLOCK ? 0 : XFS_ABSDIFF(newbno1, wantbno);
 225}
 226
 227/*
 228 * Fix up the length, based on mod and prod.
 229 * len should be k * prod + mod for some k.
 230 * If len is too small it is returned unchanged.
 231 * If len hits maxlen it is left alone.
 232 */
 233STATIC void
 234xfs_alloc_fix_len(
 235	xfs_alloc_arg_t	*args)		/* allocation argument structure */
 236{
 237	xfs_extlen_t	k;
 238	xfs_extlen_t	rlen;
 239
 240	ASSERT(args->mod < args->prod);
 241	rlen = args->len;
 242	ASSERT(rlen >= args->minlen);
 243	ASSERT(rlen <= args->maxlen);
 244	if (args->prod <= 1 || rlen < args->mod || rlen == args->maxlen ||
 245	    (args->mod == 0 && rlen < args->prod))
 246		return;
 247	k = rlen % args->prod;
 248	if (k == args->mod)
 249		return;
 250	if (k > args->mod) {
 251		if ((int)(rlen = rlen - k - args->mod) < (int)args->minlen)
 252			return;
 253	} else {
 254		if ((int)(rlen = rlen - args->prod - (args->mod - k)) <
 255		    (int)args->minlen)
 256			return;
 257	}
 258	ASSERT(rlen >= args->minlen);
 259	ASSERT(rlen <= args->maxlen);
 260	args->len = rlen;
 261}
 262
 263/*
 264 * Fix up length if there is too little space left in the a.g.
 265 * Return 1 if ok, 0 if too little, should give up.
 266 */
 267STATIC int
 268xfs_alloc_fix_minleft(
 269	xfs_alloc_arg_t	*args)		/* allocation argument structure */
 270{
 271	xfs_agf_t	*agf;		/* a.g. freelist header */
 272	int		diff;		/* free space difference */
 273
 274	if (args->minleft == 0)
 275		return 1;
 276	agf = XFS_BUF_TO_AGF(args->agbp);
 277	diff = be32_to_cpu(agf->agf_freeblks)
 278		- args->len - args->minleft;
 279	if (diff >= 0)
 280		return 1;
 281	args->len += diff;		/* shrink the allocated space */
 282	if (args->len >= args->minlen)
 283		return 1;
 284	args->agbno = NULLAGBLOCK;
 285	return 0;
 286}
 287
 288/*
 289 * Update the two btrees, logically removing from freespace the extent
 290 * starting at rbno, rlen blocks.  The extent is contained within the
 291 * actual (current) free extent fbno for flen blocks.
 292 * Flags are passed in indicating whether the cursors are set to the
 293 * relevant records.
 294 */
 295STATIC int				/* error code */
 296xfs_alloc_fixup_trees(
 297	xfs_btree_cur_t	*cnt_cur,	/* cursor for by-size btree */
 298	xfs_btree_cur_t	*bno_cur,	/* cursor for by-block btree */
 299	xfs_agblock_t	fbno,		/* starting block of free extent */
 300	xfs_extlen_t	flen,		/* length of free extent */
 301	xfs_agblock_t	rbno,		/* starting block of returned extent */
 302	xfs_extlen_t	rlen,		/* length of returned extent */
 303	int		flags)		/* flags, XFSA_FIXUP_... */
 304{
 305	int		error;		/* error code */
 306	int		i;		/* operation results */
 307	xfs_agblock_t	nfbno1;		/* first new free startblock */
 308	xfs_agblock_t	nfbno2;		/* second new free startblock */
 309	xfs_extlen_t	nflen1=0;	/* first new free length */
 310	xfs_extlen_t	nflen2=0;	/* second new free length */
 311
 312	/*
 313	 * Look up the record in the by-size tree if necessary.
 314	 */
 315	if (flags & XFSA_FIXUP_CNT_OK) {
 316#ifdef DEBUG
 317		if ((error = xfs_alloc_get_rec(cnt_cur, &nfbno1, &nflen1, &i)))
 318			return error;
 319		XFS_WANT_CORRUPTED_RETURN(
 320			i == 1 && nfbno1 == fbno && nflen1 == flen);
 321#endif
 322	} else {
 323		if ((error = xfs_alloc_lookup_eq(cnt_cur, fbno, flen, &i)))
 324			return error;
 325		XFS_WANT_CORRUPTED_RETURN(i == 1);
 326	}
 327	/*
 328	 * Look up the record in the by-block tree if necessary.
 329	 */
 330	if (flags & XFSA_FIXUP_BNO_OK) {
 331#ifdef DEBUG
 332		if ((error = xfs_alloc_get_rec(bno_cur, &nfbno1, &nflen1, &i)))
 333			return error;
 334		XFS_WANT_CORRUPTED_RETURN(
 335			i == 1 && nfbno1 == fbno && nflen1 == flen);
 336#endif
 337	} else {
 338		if ((error = xfs_alloc_lookup_eq(bno_cur, fbno, flen, &i)))
 339			return error;
 340		XFS_WANT_CORRUPTED_RETURN(i == 1);
 341	}
 342
 343#ifdef DEBUG
 344	if (bno_cur->bc_nlevels == 1 && cnt_cur->bc_nlevels == 1) {
 345		struct xfs_btree_block	*bnoblock;
 346		struct xfs_btree_block	*cntblock;
 347
 348		bnoblock = XFS_BUF_TO_BLOCK(bno_cur->bc_bufs[0]);
 349		cntblock = XFS_BUF_TO_BLOCK(cnt_cur->bc_bufs[0]);
 350
 351		XFS_WANT_CORRUPTED_RETURN(
 352			bnoblock->bb_numrecs == cntblock->bb_numrecs);
 353	}
 354#endif
 355
 356	/*
 357	 * Deal with all four cases: the allocated record is contained
 358	 * within the freespace record, so we can have new freespace
 359	 * at either (or both) end, or no freespace remaining.
 360	 */
 361	if (rbno == fbno && rlen == flen)
 362		nfbno1 = nfbno2 = NULLAGBLOCK;
 363	else if (rbno == fbno) {
 364		nfbno1 = rbno + rlen;
 365		nflen1 = flen - rlen;
 366		nfbno2 = NULLAGBLOCK;
 367	} else if (rbno + rlen == fbno + flen) {
 368		nfbno1 = fbno;
 369		nflen1 = flen - rlen;
 370		nfbno2 = NULLAGBLOCK;
 371	} else {
 372		nfbno1 = fbno;
 373		nflen1 = rbno - fbno;
 374		nfbno2 = rbno + rlen;
 375		nflen2 = (fbno + flen) - nfbno2;
 376	}
 377	/*
 378	 * Delete the entry from the by-size btree.
 379	 */
 380	if ((error = xfs_btree_delete(cnt_cur, &i)))
 381		return error;
 382	XFS_WANT_CORRUPTED_RETURN(i == 1);
 383	/*
 384	 * Add new by-size btree entry(s).
 385	 */
 386	if (nfbno1 != NULLAGBLOCK) {
 387		if ((error = xfs_alloc_lookup_eq(cnt_cur, nfbno1, nflen1, &i)))
 388			return error;
 389		XFS_WANT_CORRUPTED_RETURN(i == 0);
 390		if ((error = xfs_btree_insert(cnt_cur, &i)))
 391			return error;
 392		XFS_WANT_CORRUPTED_RETURN(i == 1);
 393	}
 394	if (nfbno2 != NULLAGBLOCK) {
 395		if ((error = xfs_alloc_lookup_eq(cnt_cur, nfbno2, nflen2, &i)))
 396			return error;
 397		XFS_WANT_CORRUPTED_RETURN(i == 0);
 398		if ((error = xfs_btree_insert(cnt_cur, &i)))
 399			return error;
 400		XFS_WANT_CORRUPTED_RETURN(i == 1);
 401	}
 402	/*
 403	 * Fix up the by-block btree entry(s).
 404	 */
 405	if (nfbno1 == NULLAGBLOCK) {
 406		/*
 407		 * No remaining freespace, just delete the by-block tree entry.
 408		 */
 409		if ((error = xfs_btree_delete(bno_cur, &i)))
 410			return error;
 411		XFS_WANT_CORRUPTED_RETURN(i == 1);
 412	} else {
 413		/*
 414		 * Update the by-block entry to start later|be shorter.
 415		 */
 416		if ((error = xfs_alloc_update(bno_cur, nfbno1, nflen1)))
 417			return error;
 418	}
 419	if (nfbno2 != NULLAGBLOCK) {
 420		/*
 421		 * 2 resulting free entries, need to add one.
 422		 */
 423		if ((error = xfs_alloc_lookup_eq(bno_cur, nfbno2, nflen2, &i)))
 424			return error;
 425		XFS_WANT_CORRUPTED_RETURN(i == 0);
 426		if ((error = xfs_btree_insert(bno_cur, &i)))
 427			return error;
 428		XFS_WANT_CORRUPTED_RETURN(i == 1);
 429	}
 430	return 0;
 431}
 432
 433static void
 434xfs_agfl_verify(
 435	struct xfs_buf	*bp)
 436{
 437#ifdef WHEN_CRCS_COME_ALONG
 438	/*
 439	 * we cannot actually do any verification of the AGFL because mkfs does
 440	 * not initialise the AGFL to zero or NULL. Hence the only valid part of
 441	 * the AGFL is what the AGF says is active. We can't get to the AGF, so
 442	 * we can't verify just those entries are valid.
 443	 *
 444	 * This problem goes away when the CRC format change comes along as that
 445	 * requires the AGFL to be initialised by mkfs. At that point, we can
 446	 * verify the blocks in the agfl -active or not- lie within the bounds
 447	 * of the AG. Until then, just leave this check ifdef'd out.
 448	 */
 449	struct xfs_mount *mp = bp->b_target->bt_mount;
 450	struct xfs_agfl	*agfl = XFS_BUF_TO_AGFL(bp);
 451	int		agfl_ok = 1;
 452
 453	int		i;
 454
 455	for (i = 0; i < XFS_AGFL_SIZE(mp); i++) {
 456		if (be32_to_cpu(agfl->agfl_bno[i]) == NULLAGBLOCK ||
 457		    be32_to_cpu(agfl->agfl_bno[i]) >= mp->m_sb.sb_agblocks)
 458			agfl_ok = 0;
 459	}
 460
 461	if (!agfl_ok) {
 462		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, agfl);
 463		xfs_buf_ioerror(bp, EFSCORRUPTED);
 464	}
 465#endif
 466}
 467
 468static void
 469xfs_agfl_write_verify(
 470	struct xfs_buf	*bp)
 471{
 472	xfs_agfl_verify(bp);
 473}
 474
 475static void
 476xfs_agfl_read_verify(
 477	struct xfs_buf	*bp)
 478{
 479	xfs_agfl_verify(bp);
 480}
 481
 482const struct xfs_buf_ops xfs_agfl_buf_ops = {
 483	.verify_read = xfs_agfl_read_verify,
 484	.verify_write = xfs_agfl_write_verify,
 485};
 486
 487/*
 488 * Read in the allocation group free block array.
 489 */
 490STATIC int				/* error */
 491xfs_alloc_read_agfl(
 492	xfs_mount_t	*mp,		/* mount point structure */
 493	xfs_trans_t	*tp,		/* transaction pointer */
 494	xfs_agnumber_t	agno,		/* allocation group number */
 495	xfs_buf_t	**bpp)		/* buffer for the ag free block array */
 496{
 497	xfs_buf_t	*bp;		/* return value */
 498	int		error;
 499
 500	ASSERT(agno != NULLAGNUMBER);
 501	error = xfs_trans_read_buf(
 502			mp, tp, mp->m_ddev_targp,
 503			XFS_AG_DADDR(mp, agno, XFS_AGFL_DADDR(mp)),
 504			XFS_FSS_TO_BB(mp, 1), 0, &bp, &xfs_agfl_buf_ops);
 505	if (error)
 506		return error;
 507	ASSERT(!xfs_buf_geterror(bp));
 508	xfs_buf_set_ref(bp, XFS_AGFL_REF);
 509	*bpp = bp;
 510	return 0;
 511}
 512
 513STATIC int
 514xfs_alloc_update_counters(
 515	struct xfs_trans	*tp,
 516	struct xfs_perag	*pag,
 517	struct xfs_buf		*agbp,
 518	long			len)
 519{
 520	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agbp);
 521
 522	pag->pagf_freeblks += len;
 523	be32_add_cpu(&agf->agf_freeblks, len);
 524
 525	xfs_trans_agblocks_delta(tp, len);
 526	if (unlikely(be32_to_cpu(agf->agf_freeblks) >
 527		     be32_to_cpu(agf->agf_length)))
 528		return EFSCORRUPTED;
 529
 530	xfs_alloc_log_agf(tp, agbp, XFS_AGF_FREEBLKS);
 531	return 0;
 532}
 533
 534/*
 535 * Allocation group level functions.
 536 */
 537
 538/*
 539 * Allocate a variable extent in the allocation group agno.
 540 * Type and bno are used to determine where in the allocation group the
 541 * extent will start.
 542 * Extent's length (returned in *len) will be between minlen and maxlen,
 543 * and of the form k * prod + mod unless there's nothing that large.
 544 * Return the starting a.g. block, or NULLAGBLOCK if we can't do it.
 545 */
 546STATIC int			/* error */
 547xfs_alloc_ag_vextent(
 548	xfs_alloc_arg_t	*args)	/* argument structure for allocation */
 549{
 550	int		error=0;
 551
 552	ASSERT(args->minlen > 0);
 553	ASSERT(args->maxlen > 0);
 554	ASSERT(args->minlen <= args->maxlen);
 555	ASSERT(args->mod < args->prod);
 556	ASSERT(args->alignment > 0);
 557	/*
 558	 * Branch to correct routine based on the type.
 559	 */
 560	args->wasfromfl = 0;
 561	switch (args->type) {
 562	case XFS_ALLOCTYPE_THIS_AG:
 563		error = xfs_alloc_ag_vextent_size(args);
 564		break;
 565	case XFS_ALLOCTYPE_NEAR_BNO:
 566		error = xfs_alloc_ag_vextent_near(args);
 567		break;
 568	case XFS_ALLOCTYPE_THIS_BNO:
 569		error = xfs_alloc_ag_vextent_exact(args);
 570		break;
 571	default:
 572		ASSERT(0);
 573		/* NOTREACHED */
 574	}
 575
 576	if (error || args->agbno == NULLAGBLOCK)
 577		return error;
 578
 579	ASSERT(args->len >= args->minlen);
 580	ASSERT(args->len <= args->maxlen);
 581	ASSERT(!args->wasfromfl || !args->isfl);
 582	ASSERT(args->agbno % args->alignment == 0);
 583
 584	if (!args->wasfromfl) {
 585		error = xfs_alloc_update_counters(args->tp, args->pag,
 586						  args->agbp,
 587						  -((long)(args->len)));
 588		if (error)
 589			return error;
 590
 591		ASSERT(!xfs_extent_busy_search(args->mp, args->agno,
 592					      args->agbno, args->len));
 593	}
 594
 595	if (!args->isfl) {
 596		xfs_trans_mod_sb(args->tp, args->wasdel ?
 597				 XFS_TRANS_SB_RES_FDBLOCKS :
 598				 XFS_TRANS_SB_FDBLOCKS,
 599				 -((long)(args->len)));
 600	}
 601
 602	XFS_STATS_INC(xs_allocx);
 603	XFS_STATS_ADD(xs_allocb, args->len);
 604	return error;
 605}
 606
 607/*
 608 * Allocate a variable extent at exactly agno/bno.
 609 * Extent's length (returned in *len) will be between minlen and maxlen,
 610 * and of the form k * prod + mod unless there's nothing that large.
 611 * Return the starting a.g. block (bno), or NULLAGBLOCK if we can't do it.
 612 */
 613STATIC int			/* error */
 614xfs_alloc_ag_vextent_exact(
 615	xfs_alloc_arg_t	*args)	/* allocation argument structure */
 616{
 617	xfs_btree_cur_t	*bno_cur;/* by block-number btree cursor */
 618	xfs_btree_cur_t	*cnt_cur;/* by count btree cursor */
 619	int		error;
 620	xfs_agblock_t	fbno;	/* start block of found extent */
 621	xfs_extlen_t	flen;	/* length of found extent */
 622	xfs_agblock_t	tbno;	/* start block of trimmed extent */
 623	xfs_extlen_t	tlen;	/* length of trimmed extent */
 624	xfs_agblock_t	tend;	/* end block of trimmed extent */
 625	int		i;	/* success/failure of operation */
 626
 627	ASSERT(args->alignment == 1);
 628
 629	/*
 630	 * Allocate/initialize a cursor for the by-number freespace btree.
 631	 */
 632	bno_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
 633					  args->agno, XFS_BTNUM_BNO);
 634
 635	/*
 636	 * Lookup bno and minlen in the btree (minlen is irrelevant, really).
 637	 * Look for the closest free block <= bno, it must contain bno
 638	 * if any free block does.
 639	 */
 640	error = xfs_alloc_lookup_le(bno_cur, args->agbno, args->minlen, &i);
 641	if (error)
 642		goto error0;
 643	if (!i)
 644		goto not_found;
 645
 646	/*
 647	 * Grab the freespace record.
 648	 */
 649	error = xfs_alloc_get_rec(bno_cur, &fbno, &flen, &i);
 650	if (error)
 651		goto error0;
 652	XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 653	ASSERT(fbno <= args->agbno);
 654
 655	/*
 656	 * Check for overlapping busy extents.
 657	 */
 658	xfs_extent_busy_trim(args, fbno, flen, &tbno, &tlen);
 659
 660	/*
 661	 * Give up if the start of the extent is busy, or the freespace isn't
 662	 * long enough for the minimum request.
 663	 */
 664	if (tbno > args->agbno)
 665		goto not_found;
 666	if (tlen < args->minlen)
 667		goto not_found;
 668	tend = tbno + tlen;
 669	if (tend < args->agbno + args->minlen)
 670		goto not_found;
 671
 672	/*
 673	 * End of extent will be smaller of the freespace end and the
 674	 * maximal requested end.
 675	 *
 676	 * Fix the length according to mod and prod if given.
 677	 */
 678	args->len = XFS_AGBLOCK_MIN(tend, args->agbno + args->maxlen)
 679						- args->agbno;
 680	xfs_alloc_fix_len(args);
 681	if (!xfs_alloc_fix_minleft(args))
 682		goto not_found;
 683
 684	ASSERT(args->agbno + args->len <= tend);
 685
 686	/*
 687	 * We are allocating agbno for args->len
 688	 * Allocate/initialize a cursor for the by-size btree.
 689	 */
 690	cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
 691		args->agno, XFS_BTNUM_CNT);
 692	ASSERT(args->agbno + args->len <=
 693		be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
 694	error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen, args->agbno,
 695				      args->len, XFSA_FIXUP_BNO_OK);
 696	if (error) {
 697		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
 698		goto error0;
 699	}
 700
 701	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
 702	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
 703
 704	args->wasfromfl = 0;
 705	trace_xfs_alloc_exact_done(args);
 706	return 0;
 707
 708not_found:
 709	/* Didn't find it, return null. */
 710	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
 711	args->agbno = NULLAGBLOCK;
 712	trace_xfs_alloc_exact_notfound(args);
 713	return 0;
 714
 715error0:
 716	xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
 717	trace_xfs_alloc_exact_error(args);
 718	return error;
 719}
 720
 721/*
 722 * Search the btree in a given direction via the search cursor and compare
 723 * the records found against the good extent we've already found.
 724 */
 725STATIC int
 726xfs_alloc_find_best_extent(
 727	struct xfs_alloc_arg	*args,	/* allocation argument structure */
 728	struct xfs_btree_cur	**gcur,	/* good cursor */
 729	struct xfs_btree_cur	**scur,	/* searching cursor */
 730	xfs_agblock_t		gdiff,	/* difference for search comparison */
 731	xfs_agblock_t		*sbno,	/* extent found by search */
 732	xfs_extlen_t		*slen,	/* extent length */
 733	xfs_agblock_t		*sbnoa,	/* aligned extent found by search */
 734	xfs_extlen_t		*slena,	/* aligned extent length */
 735	int			dir)	/* 0 = search right, 1 = search left */
 736{
 737	xfs_agblock_t		new;
 738	xfs_agblock_t		sdiff;
 739	int			error;
 740	int			i;
 741
 742	/* The good extent is perfect, no need to  search. */
 743	if (!gdiff)
 744		goto out_use_good;
 745
 746	/*
 747	 * Look until we find a better one, run out of space or run off the end.
 748	 */
 749	do {
 750		error = xfs_alloc_get_rec(*scur, sbno, slen, &i);
 751		if (error)
 752			goto error0;
 753		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 754		xfs_alloc_compute_aligned(args, *sbno, *slen, sbnoa, slena);
 755
 756		/*
 757		 * The good extent is closer than this one.
 758		 */
 759		if (!dir) {
 760			if (*sbnoa >= args->agbno + gdiff)
 761				goto out_use_good;
 762		} else {
 763			if (*sbnoa <= args->agbno - gdiff)
 764				goto out_use_good;
 765		}
 766
 767		/*
 768		 * Same distance, compare length and pick the best.
 769		 */
 770		if (*slena >= args->minlen) {
 771			args->len = XFS_EXTLEN_MIN(*slena, args->maxlen);
 772			xfs_alloc_fix_len(args);
 773
 774			sdiff = xfs_alloc_compute_diff(args->agbno, args->len,
 775						       args->alignment, *sbnoa,
 776						       *slena, &new);
 777
 778			/*
 779			 * Choose closer size and invalidate other cursor.
 780			 */
 781			if (sdiff < gdiff)
 782				goto out_use_search;
 783			goto out_use_good;
 784		}
 785
 786		if (!dir)
 787			error = xfs_btree_increment(*scur, 0, &i);
 788		else
 789			error = xfs_btree_decrement(*scur, 0, &i);
 790		if (error)
 791			goto error0;
 792	} while (i);
 793
 794out_use_good:
 795	xfs_btree_del_cursor(*scur, XFS_BTREE_NOERROR);
 796	*scur = NULL;
 797	return 0;
 798
 799out_use_search:
 800	xfs_btree_del_cursor(*gcur, XFS_BTREE_NOERROR);
 801	*gcur = NULL;
 802	return 0;
 803
 804error0:
 805	/* caller invalidates cursors */
 806	return error;
 807}
 808
 809/*
 810 * Allocate a variable extent near bno in the allocation group agno.
 811 * Extent's length (returned in len) will be between minlen and maxlen,
 812 * and of the form k * prod + mod unless there's nothing that large.
 813 * Return the starting a.g. block, or NULLAGBLOCK if we can't do it.
 814 */
 815STATIC int				/* error */
 816xfs_alloc_ag_vextent_near(
 817	xfs_alloc_arg_t	*args)		/* allocation argument structure */
 818{
 819	xfs_btree_cur_t	*bno_cur_gt;	/* cursor for bno btree, right side */
 820	xfs_btree_cur_t	*bno_cur_lt;	/* cursor for bno btree, left side */
 821	xfs_btree_cur_t	*cnt_cur;	/* cursor for count btree */
 822	xfs_agblock_t	gtbno;		/* start bno of right side entry */
 823	xfs_agblock_t	gtbnoa;		/* aligned ... */
 824	xfs_extlen_t	gtdiff;		/* difference to right side entry */
 825	xfs_extlen_t	gtlen;		/* length of right side entry */
 826	xfs_extlen_t	gtlena;		/* aligned ... */
 827	xfs_agblock_t	gtnew;		/* useful start bno of right side */
 828	int		error;		/* error code */
 829	int		i;		/* result code, temporary */
 830	int		j;		/* result code, temporary */
 831	xfs_agblock_t	ltbno;		/* start bno of left side entry */
 832	xfs_agblock_t	ltbnoa;		/* aligned ... */
 833	xfs_extlen_t	ltdiff;		/* difference to left side entry */
 834	xfs_extlen_t	ltlen;		/* length of left side entry */
 835	xfs_extlen_t	ltlena;		/* aligned ... */
 836	xfs_agblock_t	ltnew;		/* useful start bno of left side */
 837	xfs_extlen_t	rlen;		/* length of returned extent */
 838	int		forced = 0;
 839#if defined(DEBUG) && defined(__KERNEL__)
 840	/*
 841	 * Randomly don't execute the first algorithm.
 842	 */
 843	int		dofirst;	/* set to do first algorithm */
 844
 845	dofirst = random32() & 1;
 846#endif
 847
 848restart:
 849	bno_cur_lt = NULL;
 850	bno_cur_gt = NULL;
 851	ltlen = 0;
 852	gtlena = 0;
 853	ltlena = 0;
 854
 855	/*
 856	 * Get a cursor for the by-size btree.
 857	 */
 858	cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
 859		args->agno, XFS_BTNUM_CNT);
 860
 861	/*
 862	 * See if there are any free extents as big as maxlen.
 863	 */
 864	if ((error = xfs_alloc_lookup_ge(cnt_cur, 0, args->maxlen, &i)))
 865		goto error0;
 866	/*
 867	 * If none, then pick up the last entry in the tree unless the
 868	 * tree is empty.
 869	 */
 870	if (!i) {
 871		if ((error = xfs_alloc_ag_vextent_small(args, cnt_cur, &ltbno,
 872				&ltlen, &i)))
 873			goto error0;
 874		if (i == 0 || ltlen == 0) {
 875			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
 876			trace_xfs_alloc_near_noentry(args);
 877			return 0;
 878		}
 879		ASSERT(i == 1);
 880	}
 881	args->wasfromfl = 0;
 882
 883	/*
 884	 * First algorithm.
 885	 * If the requested extent is large wrt the freespaces available
 886	 * in this a.g., then the cursor will be pointing to a btree entry
 887	 * near the right edge of the tree.  If it's in the last btree leaf
 888	 * block, then we just examine all the entries in that block
 889	 * that are big enough, and pick the best one.
 890	 * This is written as a while loop so we can break out of it,
 891	 * but we never loop back to the top.
 892	 */
 893	while (xfs_btree_islastblock(cnt_cur, 0)) {
 894		xfs_extlen_t	bdiff;
 895		int		besti=0;
 896		xfs_extlen_t	blen=0;
 897		xfs_agblock_t	bnew=0;
 898
 899#if defined(DEBUG) && defined(__KERNEL__)
 900		if (!dofirst)
 901			break;
 902#endif
 903		/*
 904		 * Start from the entry that lookup found, sequence through
 905		 * all larger free blocks.  If we're actually pointing at a
 906		 * record smaller than maxlen, go to the start of this block,
 907		 * and skip all those smaller than minlen.
 908		 */
 909		if (ltlen || args->alignment > 1) {
 910			cnt_cur->bc_ptrs[0] = 1;
 911			do {
 912				if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno,
 913						&ltlen, &i)))
 914					goto error0;
 915				XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 916				if (ltlen >= args->minlen)
 917					break;
 918				if ((error = xfs_btree_increment(cnt_cur, 0, &i)))
 919					goto error0;
 920			} while (i);
 921			ASSERT(ltlen >= args->minlen);
 922			if (!i)
 923				break;
 924		}
 925		i = cnt_cur->bc_ptrs[0];
 926		for (j = 1, blen = 0, bdiff = 0;
 927		     !error && j && (blen < args->maxlen || bdiff > 0);
 928		     error = xfs_btree_increment(cnt_cur, 0, &j)) {
 929			/*
 930			 * For each entry, decide if it's better than
 931			 * the previous best entry.
 932			 */
 933			if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno, &ltlen, &i)))
 934				goto error0;
 935			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 936			xfs_alloc_compute_aligned(args, ltbno, ltlen,
 937						  &ltbnoa, &ltlena);
 938			if (ltlena < args->minlen)
 939				continue;
 940			args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
 941			xfs_alloc_fix_len(args);
 942			ASSERT(args->len >= args->minlen);
 943			if (args->len < blen)
 944				continue;
 945			ltdiff = xfs_alloc_compute_diff(args->agbno, args->len,
 946				args->alignment, ltbnoa, ltlena, &ltnew);
 947			if (ltnew != NULLAGBLOCK &&
 948			    (args->len > blen || ltdiff < bdiff)) {
 949				bdiff = ltdiff;
 950				bnew = ltnew;
 951				blen = args->len;
 952				besti = cnt_cur->bc_ptrs[0];
 953			}
 954		}
 955		/*
 956		 * It didn't work.  We COULD be in a case where
 957		 * there's a good record somewhere, so try again.
 958		 */
 959		if (blen == 0)
 960			break;
 961		/*
 962		 * Point at the best entry, and retrieve it again.
 963		 */
 964		cnt_cur->bc_ptrs[0] = besti;
 965		if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno, &ltlen, &i)))
 966			goto error0;
 967		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
 968		ASSERT(ltbno + ltlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
 969		args->len = blen;
 970		if (!xfs_alloc_fix_minleft(args)) {
 971			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
 972			trace_xfs_alloc_near_nominleft(args);
 973			return 0;
 974		}
 975		blen = args->len;
 976		/*
 977		 * We are allocating starting at bnew for blen blocks.
 978		 */
 979		args->agbno = bnew;
 980		ASSERT(bnew >= ltbno);
 981		ASSERT(bnew + blen <= ltbno + ltlen);
 982		/*
 983		 * Set up a cursor for the by-bno tree.
 984		 */
 985		bno_cur_lt = xfs_allocbt_init_cursor(args->mp, args->tp,
 986			args->agbp, args->agno, XFS_BTNUM_BNO);
 987		/*
 988		 * Fix up the btree entries.
 989		 */
 990		if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno,
 991				ltlen, bnew, blen, XFSA_FIXUP_CNT_OK)))
 992			goto error0;
 993		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
 994		xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_NOERROR);
 995
 996		trace_xfs_alloc_near_first(args);
 997		return 0;
 998	}
 999	/*
1000	 * Second algorithm.
1001	 * Search in the by-bno tree to the left and to the right
1002	 * simultaneously, until in each case we find a space big enough,
1003	 * or run into the edge of the tree.  When we run into the edge,
1004	 * we deallocate that cursor.
1005	 * If both searches succeed, we compare the two spaces and pick
1006	 * the better one.
1007	 * With alignment, it's possible for both to fail; the upper
1008	 * level algorithm that picks allocation groups for allocations
1009	 * is not supposed to do this.
1010	 */
1011	/*
1012	 * Allocate and initialize the cursor for the leftward search.
1013	 */
1014	bno_cur_lt = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
1015		args->agno, XFS_BTNUM_BNO);
1016	/*
1017	 * Lookup <= bno to find the leftward search's starting point.
1018	 */
1019	if ((error = xfs_alloc_lookup_le(bno_cur_lt, args->agbno, args->maxlen, &i)))
1020		goto error0;
1021	if (!i) {
1022		/*
1023		 * Didn't find anything; use this cursor for the rightward
1024		 * search.
1025		 */
1026		bno_cur_gt = bno_cur_lt;
1027		bno_cur_lt = NULL;
1028	}
1029	/*
1030	 * Found something.  Duplicate the cursor for the rightward search.
1031	 */
1032	else if ((error = xfs_btree_dup_cursor(bno_cur_lt, &bno_cur_gt)))
1033		goto error0;
1034	/*
1035	 * Increment the cursor, so we will point at the entry just right
1036	 * of the leftward entry if any, or to the leftmost entry.
1037	 */
1038	if ((error = xfs_btree_increment(bno_cur_gt, 0, &i)))
1039		goto error0;
1040	if (!i) {
1041		/*
1042		 * It failed, there are no rightward entries.
1043		 */
1044		xfs_btree_del_cursor(bno_cur_gt, XFS_BTREE_NOERROR);
1045		bno_cur_gt = NULL;
1046	}
1047	/*
1048	 * Loop going left with the leftward cursor, right with the
1049	 * rightward cursor, until either both directions give up or
1050	 * we find an entry at least as big as minlen.
1051	 */
1052	do {
1053		if (bno_cur_lt) {
1054			if ((error = xfs_alloc_get_rec(bno_cur_lt, &ltbno, &ltlen, &i)))
1055				goto error0;
1056			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1057			xfs_alloc_compute_aligned(args, ltbno, ltlen,
1058						  &ltbnoa, &ltlena);
1059			if (ltlena >= args->minlen)
1060				break;
1061			if ((error = xfs_btree_decrement(bno_cur_lt, 0, &i)))
1062				goto error0;
1063			if (!i) {
1064				xfs_btree_del_cursor(bno_cur_lt,
1065						     XFS_BTREE_NOERROR);
1066				bno_cur_lt = NULL;
1067			}
1068		}
1069		if (bno_cur_gt) {
1070			if ((error = xfs_alloc_get_rec(bno_cur_gt, &gtbno, &gtlen, &i)))
1071				goto error0;
1072			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1073			xfs_alloc_compute_aligned(args, gtbno, gtlen,
1074						  &gtbnoa, &gtlena);
1075			if (gtlena >= args->minlen)
1076				break;
1077			if ((error = xfs_btree_increment(bno_cur_gt, 0, &i)))
1078				goto error0;
1079			if (!i) {
1080				xfs_btree_del_cursor(bno_cur_gt,
1081						     XFS_BTREE_NOERROR);
1082				bno_cur_gt = NULL;
1083			}
1084		}
1085	} while (bno_cur_lt || bno_cur_gt);
1086
1087	/*
1088	 * Got both cursors still active, need to find better entry.
1089	 */
1090	if (bno_cur_lt && bno_cur_gt) {
1091		if (ltlena >= args->minlen) {
1092			/*
1093			 * Left side is good, look for a right side entry.
1094			 */
1095			args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
1096			xfs_alloc_fix_len(args);
1097			ltdiff = xfs_alloc_compute_diff(args->agbno, args->len,
1098				args->alignment, ltbnoa, ltlena, &ltnew);
1099
1100			error = xfs_alloc_find_best_extent(args,
1101						&bno_cur_lt, &bno_cur_gt,
1102						ltdiff, &gtbno, &gtlen,
1103						&gtbnoa, &gtlena,
1104						0 /* search right */);
1105		} else {
1106			ASSERT(gtlena >= args->minlen);
1107
1108			/*
1109			 * Right side is good, look for a left side entry.
1110			 */
1111			args->len = XFS_EXTLEN_MIN(gtlena, args->maxlen);
1112			xfs_alloc_fix_len(args);
1113			gtdiff = xfs_alloc_compute_diff(args->agbno, args->len,
1114				args->alignment, gtbnoa, gtlena, &gtnew);
1115
1116			error = xfs_alloc_find_best_extent(args,
1117						&bno_cur_gt, &bno_cur_lt,
1118						gtdiff, &ltbno, &ltlen,
1119						&ltbnoa, &ltlena,
1120						1 /* search left */);
1121		}
1122
1123		if (error)
1124			goto error0;
1125	}
1126
1127	/*
1128	 * If we couldn't get anything, give up.
1129	 */
1130	if (bno_cur_lt == NULL && bno_cur_gt == NULL) {
1131		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1132
1133		if (!forced++) {
1134			trace_xfs_alloc_near_busy(args);
1135			xfs_log_force(args->mp, XFS_LOG_SYNC);
1136			goto restart;
1137		}
1138		trace_xfs_alloc_size_neither(args);
1139		args->agbno = NULLAGBLOCK;
1140		return 0;
1141	}
1142
1143	/*
1144	 * At this point we have selected a freespace entry, either to the
1145	 * left or to the right.  If it's on the right, copy all the
1146	 * useful variables to the "left" set so we only have one
1147	 * copy of this code.
1148	 */
1149	if (bno_cur_gt) {
1150		bno_cur_lt = bno_cur_gt;
1151		bno_cur_gt = NULL;
1152		ltbno = gtbno;
1153		ltbnoa = gtbnoa;
1154		ltlen = gtlen;
1155		ltlena = gtlena;
1156		j = 1;
1157	} else
1158		j = 0;
1159
1160	/*
1161	 * Fix up the length and compute the useful address.
1162	 */
1163	args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
1164	xfs_alloc_fix_len(args);
1165	if (!xfs_alloc_fix_minleft(args)) {
1166		trace_xfs_alloc_near_nominleft(args);
1167		xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_NOERROR);
1168		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1169		return 0;
1170	}
1171	rlen = args->len;
1172	(void)xfs_alloc_compute_diff(args->agbno, rlen, args->alignment,
1173				     ltbnoa, ltlena, &ltnew);
1174	ASSERT(ltnew >= ltbno);
1175	ASSERT(ltnew + rlen <= ltbnoa + ltlena);
1176	ASSERT(ltnew + rlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
1177	args->agbno = ltnew;
1178
1179	if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno, ltlen,
1180			ltnew, rlen, XFSA_FIXUP_BNO_OK)))
1181		goto error0;
1182
1183	if (j)
1184		trace_xfs_alloc_near_greater(args);
1185	else
1186		trace_xfs_alloc_near_lesser(args);
1187
1188	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1189	xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_NOERROR);
1190	return 0;
1191
1192 error0:
1193	trace_xfs_alloc_near_error(args);
1194	if (cnt_cur != NULL)
1195		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
1196	if (bno_cur_lt != NULL)
1197		xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_ERROR);
1198	if (bno_cur_gt != NULL)
1199		xfs_btree_del_cursor(bno_cur_gt, XFS_BTREE_ERROR);
1200	return error;
1201}
1202
1203/*
1204 * Allocate a variable extent anywhere in the allocation group agno.
1205 * Extent's length (returned in len) will be between minlen and maxlen,
1206 * and of the form k * prod + mod unless there's nothing that large.
1207 * Return the starting a.g. block, or NULLAGBLOCK if we can't do it.
1208 */
1209STATIC int				/* error */
1210xfs_alloc_ag_vextent_size(
1211	xfs_alloc_arg_t	*args)		/* allocation argument structure */
1212{
1213	xfs_btree_cur_t	*bno_cur;	/* cursor for bno btree */
1214	xfs_btree_cur_t	*cnt_cur;	/* cursor for cnt btree */
1215	int		error;		/* error result */
1216	xfs_agblock_t	fbno;		/* start of found freespace */
1217	xfs_extlen_t	flen;		/* length of found freespace */
1218	int		i;		/* temp status variable */
1219	xfs_agblock_t	rbno;		/* returned block number */
1220	xfs_extlen_t	rlen;		/* length of returned extent */
1221	int		forced = 0;
1222
1223restart:
1224	/*
1225	 * Allocate and initialize a cursor for the by-size btree.
1226	 */
1227	cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
1228		args->agno, XFS_BTNUM_CNT);
1229	bno_cur = NULL;
1230
1231	/*
1232	 * Look for an entry >= maxlen+alignment-1 blocks.
1233	 */
1234	if ((error = xfs_alloc_lookup_ge(cnt_cur, 0,
1235			args->maxlen + args->alignment - 1, &i)))
1236		goto error0;
1237
1238	/*
1239	 * If none or we have busy extents that we cannot allocate from, then
1240	 * we have to settle for a smaller extent. In the case that there are
1241	 * no large extents, this will return the last entry in the tree unless
1242	 * the tree is empty. In the case that there are only busy large
1243	 * extents, this will return the largest small extent unless there
1244	 * are no smaller extents available.
1245	 */
1246	if (!i || forced > 1) {
1247		error = xfs_alloc_ag_vextent_small(args, cnt_cur,
1248						   &fbno, &flen, &i);
1249		if (error)
1250			goto error0;
1251		if (i == 0 || flen == 0) {
1252			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1253			trace_xfs_alloc_size_noentry(args);
1254			return 0;
1255		}
1256		ASSERT(i == 1);
1257		xfs_alloc_compute_aligned(args, fbno, flen, &rbno, &rlen);
1258	} else {
1259		/*
1260		 * Search for a non-busy extent that is large enough.
1261		 * If we are at low space, don't check, or if we fall of
1262		 * the end of the btree, turn off the busy check and
1263		 * restart.
1264		 */
1265		for (;;) {
1266			error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen, &i);
1267			if (error)
1268				goto error0;
1269			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1270
1271			xfs_alloc_compute_aligned(args, fbno, flen,
1272						  &rbno, &rlen);
1273
1274			if (rlen >= args->maxlen)
1275				break;
1276
1277			error = xfs_btree_increment(cnt_cur, 0, &i);
1278			if (error)
1279				goto error0;
1280			if (i == 0) {
1281				/*
1282				 * Our only valid extents must have been busy.
1283				 * Make it unbusy by forcing the log out and
1284				 * retrying. If we've been here before, forcing
1285				 * the log isn't making the extents available,
1286				 * which means they have probably been freed in
1287				 * this transaction.  In that case, we have to
1288				 * give up on them and we'll attempt a minlen
1289				 * allocation the next time around.
1290				 */
1291				xfs_btree_del_cursor(cnt_cur,
1292						     XFS_BTREE_NOERROR);
1293				trace_xfs_alloc_size_busy(args);
1294				if (!forced++)
1295					xfs_log_force(args->mp, XFS_LOG_SYNC);
1296				goto restart;
1297			}
1298		}
1299	}
1300
1301	/*
1302	 * In the first case above, we got the last entry in the
1303	 * by-size btree.  Now we check to see if the space hits maxlen
1304	 * once aligned; if not, we search left for something better.
1305	 * This can't happen in the second case above.
1306	 */
1307	rlen = XFS_EXTLEN_MIN(args->maxlen, rlen);
1308	XFS_WANT_CORRUPTED_GOTO(rlen == 0 ||
1309			(rlen <= flen && rbno + rlen <= fbno + flen), error0);
1310	if (rlen < args->maxlen) {
1311		xfs_agblock_t	bestfbno;
1312		xfs_extlen_t	bestflen;
1313		xfs_agblock_t	bestrbno;
1314		xfs_extlen_t	bestrlen;
1315
1316		bestrlen = rlen;
1317		bestrbno = rbno;
1318		bestflen = flen;
1319		bestfbno = fbno;
1320		for (;;) {
1321			if ((error = xfs_btree_decrement(cnt_cur, 0, &i)))
1322				goto error0;
1323			if (i == 0)
1324				break;
1325			if ((error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen,
1326					&i)))
1327				goto error0;
1328			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1329			if (flen < bestrlen)
1330				break;
1331			xfs_alloc_compute_aligned(args, fbno, flen,
1332						  &rbno, &rlen);
1333			rlen = XFS_EXTLEN_MIN(args->maxlen, rlen);
1334			XFS_WANT_CORRUPTED_GOTO(rlen == 0 ||
1335				(rlen <= flen && rbno + rlen <= fbno + flen),
1336				error0);
1337			if (rlen > bestrlen) {
1338				bestrlen = rlen;
1339				bestrbno = rbno;
1340				bestflen = flen;
1341				bestfbno = fbno;
1342				if (rlen == args->maxlen)
1343					break;
1344			}
1345		}
1346		if ((error = xfs_alloc_lookup_eq(cnt_cur, bestfbno, bestflen,
1347				&i)))
1348			goto error0;
1349		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1350		rlen = bestrlen;
1351		rbno = bestrbno;
1352		flen = bestflen;
1353		fbno = bestfbno;
1354	}
1355	args->wasfromfl = 0;
1356	/*
1357	 * Fix up the length.
1358	 */
1359	args->len = rlen;
1360	if (rlen < args->minlen) {
1361		if (!forced++) {
1362			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1363			trace_xfs_alloc_size_busy(args);
1364			xfs_log_force(args->mp, XFS_LOG_SYNC);
1365			goto restart;
1366		}
1367		goto out_nominleft;
1368	}
1369	xfs_alloc_fix_len(args);
1370
1371	if (!xfs_alloc_fix_minleft(args))
1372		goto out_nominleft;
1373	rlen = args->len;
1374	XFS_WANT_CORRUPTED_GOTO(rlen <= flen, error0);
1375	/*
1376	 * Allocate and initialize a cursor for the by-block tree.
1377	 */
1378	bno_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
1379		args->agno, XFS_BTNUM_BNO);
1380	if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen,
1381			rbno, rlen, XFSA_FIXUP_CNT_OK)))
1382		goto error0;
1383	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1384	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
1385	cnt_cur = bno_cur = NULL;
1386	args->len = rlen;
1387	args->agbno = rbno;
1388	XFS_WANT_CORRUPTED_GOTO(
1389		args->agbno + args->len <=
1390			be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),
1391		error0);
1392	trace_xfs_alloc_size_done(args);
1393	return 0;
1394
1395error0:
1396	trace_xfs_alloc_size_error(args);
1397	if (cnt_cur)
1398		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
1399	if (bno_cur)
1400		xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
1401	return error;
1402
1403out_nominleft:
1404	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1405	trace_xfs_alloc_size_nominleft(args);
1406	args->agbno = NULLAGBLOCK;
1407	return 0;
1408}
1409
1410/*
1411 * Deal with the case where only small freespaces remain.
1412 * Either return the contents of the last freespace record,
1413 * or allocate space from the freelist if there is nothing in the tree.
1414 */
1415STATIC int			/* error */
1416xfs_alloc_ag_vextent_small(
1417	xfs_alloc_arg_t	*args,	/* allocation argument structure */
1418	xfs_btree_cur_t	*ccur,	/* by-size cursor */
1419	xfs_agblock_t	*fbnop,	/* result block number */
1420	xfs_extlen_t	*flenp,	/* result length */
1421	int		*stat)	/* status: 0-freelist, 1-normal/none */
1422{
1423	int		error;
1424	xfs_agblock_t	fbno;
1425	xfs_extlen_t	flen;
1426	int		i;
1427
1428	if ((error = xfs_btree_decrement(ccur, 0, &i)))
1429		goto error0;
1430	if (i) {
1431		if ((error = xfs_alloc_get_rec(ccur, &fbno, &flen, &i)))
1432			goto error0;
1433		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1434	}
1435	/*
1436	 * Nothing in the btree, try the freelist.  Make sure
1437	 * to respect minleft even when pulling from the
1438	 * freelist.
1439	 */
1440	else if (args->minlen == 1 && args->alignment == 1 && !args->isfl &&
1441		 (be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_flcount)
1442		  > args->minleft)) {
1443		error = xfs_alloc_get_freelist(args->tp, args->agbp, &fbno, 0);
1444		if (error)
1445			goto error0;
1446		if (fbno != NULLAGBLOCK) {
1447			xfs_extent_busy_reuse(args->mp, args->agno, fbno, 1,
1448					     args->userdata);
1449
1450			if (args->userdata) {
1451				xfs_buf_t	*bp;
1452
1453				bp = xfs_btree_get_bufs(args->mp, args->tp,
1454					args->agno, fbno, 0);
1455				xfs_trans_binval(args->tp, bp);
1456			}
1457			args->len = 1;
1458			args->agbno = fbno;
1459			XFS_WANT_CORRUPTED_GOTO(
1460				args->agbno + args->len <=
1461				be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),
1462				error0);
1463			args->wasfromfl = 1;
1464			trace_xfs_alloc_small_freelist(args);
1465			*stat = 0;
1466			return 0;
1467		}
1468		/*
1469		 * Nothing in the freelist.
1470		 */
1471		else
1472			flen = 0;
1473	}
1474	/*
1475	 * Can't allocate from the freelist for some reason.
1476	 */
1477	else {
1478		fbno = NULLAGBLOCK;
1479		flen = 0;
1480	}
1481	/*
1482	 * Can't do the allocation, give up.
1483	 */
1484	if (flen < args->minlen) {
1485		args->agbno = NULLAGBLOCK;
1486		trace_xfs_alloc_small_notenough(args);
1487		flen = 0;
1488	}
1489	*fbnop = fbno;
1490	*flenp = flen;
1491	*stat = 1;
1492	trace_xfs_alloc_small_done(args);
1493	return 0;
1494
1495error0:
1496	trace_xfs_alloc_small_error(args);
1497	return error;
1498}
1499
1500/*
1501 * Free the extent starting at agno/bno for length.
1502 */
1503STATIC int			/* error */
1504xfs_free_ag_extent(
1505	xfs_trans_t	*tp,	/* transaction pointer */
1506	xfs_buf_t	*agbp,	/* buffer for a.g. freelist header */
1507	xfs_agnumber_t	agno,	/* allocation group number */
1508	xfs_agblock_t	bno,	/* starting block number */
1509	xfs_extlen_t	len,	/* length of extent */
1510	int		isfl)	/* set if is freelist blocks - no sb acctg */
1511{
1512	xfs_btree_cur_t	*bno_cur;	/* cursor for by-block btree */
1513	xfs_btree_cur_t	*cnt_cur;	/* cursor for by-size btree */
1514	int		error;		/* error return value */
1515	xfs_agblock_t	gtbno;		/* start of right neighbor block */
1516	xfs_extlen_t	gtlen;		/* length of right neighbor block */
1517	int		haveleft;	/* have a left neighbor block */
1518	int		haveright;	/* have a right neighbor block */
1519	int		i;		/* temp, result code */
1520	xfs_agblock_t	ltbno;		/* start of left neighbor block */
1521	xfs_extlen_t	ltlen;		/* length of left neighbor block */
1522	xfs_mount_t	*mp;		/* mount point struct for filesystem */
1523	xfs_agblock_t	nbno;		/* new starting block of freespace */
1524	xfs_extlen_t	nlen;		/* new length of freespace */
1525	xfs_perag_t	*pag;		/* per allocation group data */
1526
1527	mp = tp->t_mountp;
1528	/*
1529	 * Allocate and initialize a cursor for the by-block btree.
1530	 */
1531	bno_cur = xfs_allocbt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_BNO);
1532	cnt_cur = NULL;
1533	/*
1534	 * Look for a neighboring block on the left (lower block numbers)
1535	 * that is contiguous with this space.
1536	 */
1537	if ((error = xfs_alloc_lookup_le(bno_cur, bno, len, &haveleft)))
1538		goto error0;
1539	if (haveleft) {
1540		/*
1541		 * There is a block to our left.
1542		 */
1543		if ((error = xfs_alloc_get_rec(bno_cur, &ltbno, &ltlen, &i)))
1544			goto error0;
1545		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1546		/*
1547		 * It's not contiguous, though.
1548		 */
1549		if (ltbno + ltlen < bno)
1550			haveleft = 0;
1551		else {
1552			/*
1553			 * If this failure happens the request to free this
1554			 * space was invalid, it's (partly) already free.
1555			 * Very bad.
1556			 */
1557			XFS_WANT_CORRUPTED_GOTO(ltbno + ltlen <= bno, error0);
1558		}
1559	}
1560	/*
1561	 * Look for a neighboring block on the right (higher block numbers)
1562	 * that is contiguous with this space.
1563	 */
1564	if ((error = xfs_btree_increment(bno_cur, 0, &haveright)))
1565		goto error0;
1566	if (haveright) {
1567		/*
1568		 * There is a block to our right.
1569		 */
1570		if ((error = xfs_alloc_get_rec(bno_cur, &gtbno, &gtlen, &i)))
1571			goto error0;
1572		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1573		/*
1574		 * It's not contiguous, though.
1575		 */
1576		if (bno + len < gtbno)
1577			haveright = 0;
1578		else {
1579			/*
1580			 * If this failure happens the request to free this
1581			 * space was invalid, it's (partly) already free.
1582			 * Very bad.
1583			 */
1584			XFS_WANT_CORRUPTED_GOTO(gtbno >= bno + len, error0);
1585		}
1586	}
1587	/*
1588	 * Now allocate and initialize a cursor for the by-size tree.
1589	 */
1590	cnt_cur = xfs_allocbt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_CNT);
1591	/*
1592	 * Have both left and right contiguous neighbors.
1593	 * Merge all three into a single free block.
1594	 */
1595	if (haveleft && haveright) {
1596		/*
1597		 * Delete the old by-size entry on the left.
1598		 */
1599		if ((error = xfs_alloc_lookup_eq(cnt_cur, ltbno, ltlen, &i)))
1600			goto error0;
1601		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1602		if ((error = xfs_btree_delete(cnt_cur, &i)))
1603			goto error0;
1604		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1605		/*
1606		 * Delete the old by-size entry on the right.
1607		 */
1608		if ((error = xfs_alloc_lookup_eq(cnt_cur, gtbno, gtlen, &i)))
1609			goto error0;
1610		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1611		if ((error = xfs_btree_delete(cnt_cur, &i)))
1612			goto error0;
1613		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1614		/*
1615		 * Delete the old by-block entry for the right block.
1616		 */
1617		if ((error = xfs_btree_delete(bno_cur, &i)))
1618			goto error0;
1619		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1620		/*
1621		 * Move the by-block cursor back to the left neighbor.
1622		 */
1623		if ((error = xfs_btree_decrement(bno_cur, 0, &i)))
1624			goto error0;
1625		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1626#ifdef DEBUG
1627		/*
1628		 * Check that this is the right record: delete didn't
1629		 * mangle the cursor.
1630		 */
1631		{
1632			xfs_agblock_t	xxbno;
1633			xfs_extlen_t	xxlen;
1634
1635			if ((error = xfs_alloc_get_rec(bno_cur, &xxbno, &xxlen,
1636					&i)))
1637				goto error0;
1638			XFS_WANT_CORRUPTED_GOTO(
1639				i == 1 && xxbno == ltbno && xxlen == ltlen,
1640				error0);
1641		}
1642#endif
1643		/*
1644		 * Update remaining by-block entry to the new, joined block.
1645		 */
1646		nbno = ltbno;
1647		nlen = len + ltlen + gtlen;
1648		if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
1649			goto error0;
1650	}
1651	/*
1652	 * Have only a left contiguous neighbor.
1653	 * Merge it together with the new freespace.
1654	 */
1655	else if (haveleft) {
1656		/*
1657		 * Delete the old by-size entry on the left.
1658		 */
1659		if ((error = xfs_alloc_lookup_eq(cnt_cur, ltbno, ltlen, &i)))
1660			goto error0;
1661		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1662		if ((error = xfs_btree_delete(cnt_cur, &i)))
1663			goto error0;
1664		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1665		/*
1666		 * Back up the by-block cursor to the left neighbor, and
1667		 * update its length.
1668		 */
1669		if ((error = xfs_btree_decrement(bno_cur, 0, &i)))
1670			goto error0;
1671		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1672		nbno = ltbno;
1673		nlen = len + ltlen;
1674		if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
1675			goto error0;
1676	}
1677	/*
1678	 * Have only a right contiguous neighbor.
1679	 * Merge it together with the new freespace.
1680	 */
1681	else if (haveright) {
1682		/*
1683		 * Delete the old by-size entry on the right.
1684		 */
1685		if ((error = xfs_alloc_lookup_eq(cnt_cur, gtbno, gtlen, &i)))
1686			goto error0;
1687		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1688		if ((error = xfs_btree_delete(cnt_cur, &i)))
1689			goto error0;
1690		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1691		/*
1692		 * Update the starting block and length of the right
1693		 * neighbor in the by-block tree.
1694		 */
1695		nbno = bno;
1696		nlen = len + gtlen;
1697		if ((error = xfs_alloc_update(bno_cur, nbno, nlen)))
1698			goto error0;
1699	}
1700	/*
1701	 * No contiguous neighbors.
1702	 * Insert the new freespace into the by-block tree.
1703	 */
1704	else {
1705		nbno = bno;
1706		nlen = len;
1707		if ((error = xfs_btree_insert(bno_cur, &i)))
1708			goto error0;
1709		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1710	}
1711	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
1712	bno_cur = NULL;
1713	/*
1714	 * In all cases we need to insert the new freespace in the by-size tree.
1715	 */
1716	if ((error = xfs_alloc_lookup_eq(cnt_cur, nbno, nlen, &i)))
1717		goto error0;
1718	XFS_WANT_CORRUPTED_GOTO(i == 0, error0);
1719	if ((error = xfs_btree_insert(cnt_cur, &i)))
1720		goto error0;
1721	XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
1722	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
1723	cnt_cur = NULL;
1724
1725	/*
1726	 * Update the freespace totals in the ag and superblock.
1727	 */
1728	pag = xfs_perag_get(mp, agno);
1729	error = xfs_alloc_update_counters(tp, pag, agbp, len);
1730	xfs_perag_put(pag);
1731	if (error)
1732		goto error0;
1733
1734	if (!isfl)
1735		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (long)len);
1736	XFS_STATS_INC(xs_freex);
1737	XFS_STATS_ADD(xs_freeb, len);
1738
1739	trace_xfs_free_extent(mp, agno, bno, len, isfl, haveleft, haveright);
1740
1741	return 0;
1742
1743 error0:
1744	trace_xfs_free_extent(mp, agno, bno, len, isfl, -1, -1);
1745	if (bno_cur)
1746		xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
1747	if (cnt_cur)
1748		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
1749	return error;
1750}
1751
1752/*
1753 * Visible (exported) allocation/free functions.
1754 * Some of these are used just by xfs_alloc_btree.c and this file.
1755 */
1756
1757/*
1758 * Compute and fill in value of m_ag_maxlevels.
1759 */
1760void
1761xfs_alloc_compute_maxlevels(
1762	xfs_mount_t	*mp)	/* file system mount structure */
1763{
1764	int		level;
1765	uint		maxblocks;
1766	uint		maxleafents;
1767	int		minleafrecs;
1768	int		minnoderecs;
1769
1770	maxleafents = (mp->m_sb.sb_agblocks + 1) / 2;
1771	minleafrecs = mp->m_alloc_mnr[0];
1772	minnoderecs = mp->m_alloc_mnr[1];
1773	maxblocks = (maxleafents + minleafrecs - 1) / minleafrecs;
1774	for (level = 1; maxblocks > 1; level++)
1775		maxblocks = (maxblocks + minnoderecs - 1) / minnoderecs;
1776	mp->m_ag_maxlevels = level;
1777}
1778
1779/*
1780 * Find the length of the longest extent in an AG.
1781 */
1782xfs_extlen_t
1783xfs_alloc_longest_free_extent(
1784	struct xfs_mount	*mp,
1785	struct xfs_perag	*pag)
1786{
1787	xfs_extlen_t		need, delta = 0;
1788
1789	need = XFS_MIN_FREELIST_PAG(pag, mp);
1790	if (need > pag->pagf_flcount)
1791		delta = need - pag->pagf_flcount;
1792
1793	if (pag->pagf_longe

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