Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 2623 insertions, 0 deletions

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
new file mode 100644
index 00000000000..36603db10fe
--- /dev/null
+++ b/fs/xfs/xfs_alloc.c
@@ -0,0 +1,2623 @@
+/*
+ * Copyright (c) 2000-2002 Silicon Graphics, Inc.  All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 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.
+ *
+ * Further, this software is distributed without any warranty that it is
+ * free of the rightful claim of any third person regarding infringement
+ * or the like.  Any license provided herein, whether implied or
+ * otherwise, applies only to this software file.  Patent licenses, if
+ * any, provided herein do not apply to combinations of this program with
+ * other software, or any other product whatsoever.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
+ * Mountain View, CA  94043, or:
+ *
+ * http://www.sgi.com
+ *
+ * For further information regarding this notice, see:
+ *
+ * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
+ */
+
+/*
+ * Free space allocation for XFS.
+ */
+#include "xfs.h"
+#include "xfs_macros.h"
+#include "xfs_types.h"
+#include "xfs_inum.h"
+#include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_ag.h"
+#include "xfs_dir.h"
+#include "xfs_dmapi.h"
+#include "xfs_mount.h"
+#include "xfs_alloc_btree.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_btree.h"
+#include "xfs_ialloc.h"
+#include "xfs_alloc.h"
+#include "xfs_bit.h"
+#include "xfs_error.h"
+
+
+#define XFS_ABSDIFF(a,b)	(((a) <= (b)) ? ((b) - (a)) : ((a) - (b)))
+
+#define	XFSA_FIXUP_BNO_OK	1
+#define	XFSA_FIXUP_CNT_OK	2
+
+int
+xfs_alloc_search_busy(xfs_trans_t *tp,
+		    xfs_agnumber_t agno,
+		    xfs_agblock_t bno,
+		    xfs_extlen_t len);
+
+#if defined(XFS_ALLOC_TRACE)
+ktrace_t *xfs_alloc_trace_buf;
+
+#define	TRACE_ALLOC(s,a)	\
+	xfs_alloc_trace_alloc(fname, s, a, __LINE__)
+#define	TRACE_FREE(s,a,b,x,f)	\
+	xfs_alloc_trace_free(fname, s, mp, a, b, x, f, __LINE__)
+#define	TRACE_MODAGF(s,a,f)	\
+	xfs_alloc_trace_modagf(fname, s, mp, a, f, __LINE__)
+#define	TRACE_BUSY(fname,s,ag,agb,l,sl,tp)	\
+	xfs_alloc_trace_busy(fname, s, mp, ag, agb, l, sl, tp, XFS_ALLOC_KTRACE_BUSY, __LINE__)
+#define	TRACE_UNBUSY(fname,s,ag,sl,tp)	\
+	xfs_alloc_trace_busy(fname, s, mp, ag, -1, -1, sl, tp, XFS_ALLOC_KTRACE_UNBUSY, __LINE__)
+#define	TRACE_BUSYSEARCH(fname,s,ag,agb,l,sl,tp)	\
+	xfs_alloc_trace_busy(fname, s, mp, ag, agb, l, sl, tp, XFS_ALLOC_KTRACE_BUSYSEARCH, __LINE__)
+#else
+#define	TRACE_ALLOC(s,a)
+#define	TRACE_FREE(s,a,b,x,f)
+#define	TRACE_MODAGF(s,a,f)
+#define	TRACE_BUSY(s,a,ag,agb,l,sl,tp)
+#define	TRACE_UNBUSY(fname,s,ag,sl,tp)
+#define	TRACE_BUSYSEARCH(fname,s,ag,agb,l,sl,tp)
+#endif	/* XFS_ALLOC_TRACE */
+
+/*
+ * Prototypes for per-ag allocation routines
+ */
+
+STATIC int xfs_alloc_ag_vextent_exact(xfs_alloc_arg_t *);
+STATIC int xfs_alloc_ag_vextent_near(xfs_alloc_arg_t *);
+STATIC int xfs_alloc_ag_vextent_size(xfs_alloc_arg_t *);
+STATIC int xfs_alloc_ag_vextent_small(xfs_alloc_arg_t *,
+	xfs_btree_cur_t *, xfs_agblock_t *, xfs_extlen_t *, int *);
+
+/*
+ * Internal functions.
+ */
+
+/*
+ * Compute aligned version of the found extent.
+ * Takes alignment and min length into account.
+ */
+STATIC int				/* success (>= minlen) */
+xfs_alloc_compute_aligned(
+	xfs_agblock_t	foundbno,	/* starting block in found extent */
+	xfs_extlen_t	foundlen,	/* length in found extent */
+	xfs_extlen_t	alignment,	/* alignment for allocation */
+	xfs_extlen_t	minlen,		/* minimum length for allocation */
+	xfs_agblock_t	*resbno,	/* result block number */
+	xfs_extlen_t	*reslen)	/* result length */
+{
+	xfs_agblock_t	bno;
+	xfs_extlen_t	diff;
+	xfs_extlen_t	len;
+
+	if (alignment > 1 && foundlen >= minlen) {
+		bno = roundup(foundbno, alignment);
+		diff = bno - foundbno;
+		len = diff >= foundlen ? 0 : foundlen - diff;
+	} else {
+		bno = foundbno;
+		len = foundlen;
+	}
+	*resbno = bno;
+	*reslen = len;
+	return len >= minlen;
+}
+
+/*
+ * Compute best start block and diff for "near" allocations.
+ * freelen >= wantlen already checked by caller.
+ */
+STATIC xfs_extlen_t			/* difference value (absolute) */
+xfs_alloc_compute_diff(
+	xfs_agblock_t	wantbno,	/* target starting block */
+	xfs_extlen_t	wantlen,	/* target length */
+	xfs_extlen_t	alignment,	/* target alignment */
+	xfs_agblock_t	freebno,	/* freespace's starting block */
+	xfs_extlen_t	freelen,	/* freespace's length */
+	xfs_agblock_t	*newbnop)	/* result: best start block from free */
+{
+	xfs_agblock_t	freeend;	/* end of freespace extent */
+	xfs_agblock_t	newbno1;	/* return block number */
+	xfs_agblock_t	newbno2;	/* other new block number */
+	xfs_extlen_t	newlen1=0;	/* length with newbno1 */
+	xfs_extlen_t	newlen2=0;	/* length with newbno2 */
+	xfs_agblock_t	wantend;	/* end of target extent */
+
+	ASSERT(freelen >= wantlen);
+	freeend = freebno + freelen;
+	wantend = wantbno + wantlen;
+	if (freebno >= wantbno) {
+		if ((newbno1 = roundup(freebno, alignment)) >= freeend)
+			newbno1 = NULLAGBLOCK;
+	} else if (freeend >= wantend && alignment > 1) {
+		newbno1 = roundup(wantbno, alignment);
+		newbno2 = newbno1 - alignment;
+		if (newbno1 >= freeend)
+			newbno1 = NULLAGBLOCK;
+		else
+			newlen1 = XFS_EXTLEN_MIN(wantlen, freeend - newbno1);
+		if (newbno2 < freebno)
+			newbno2 = NULLAGBLOCK;
+		else
+			newlen2 = XFS_EXTLEN_MIN(wantlen, freeend - newbno2);
+		if (newbno1 != NULLAGBLOCK && newbno2 != NULLAGBLOCK) {
+			if (newlen1 < newlen2 ||
+			    (newlen1 == newlen2 &&
+			     XFS_ABSDIFF(newbno1, wantbno) >
+			     XFS_ABSDIFF(newbno2, wantbno)))
+				newbno1 = newbno2;
+		} else if (newbno2 != NULLAGBLOCK)
+			newbno1 = newbno2;
+	} else if (freeend >= wantend) {
+		newbno1 = wantbno;
+	} else if (alignment > 1) {
+		newbno1 = roundup(freeend - wantlen, alignment);
+		if (newbno1 > freeend - wantlen &&
+		    newbno1 - alignment >= freebno)
+			newbno1 -= alignment;
+		else if (newbno1 >= freeend)
+			newbno1 = NULLAGBLOCK;
+	} else
+		newbno1 = freeend - wantlen;
+	*newbnop = newbno1;
+	return newbno1 == NULLAGBLOCK ? 0 : XFS_ABSDIFF(newbno1, wantbno);
+}
+
+/*
+ * Fix up the length, based on mod and prod.
+ * len should be k * prod + mod for some k.
+ * If len is too small it is returned unchanged.
+ * If len hits maxlen it is left alone.
+ */
+STATIC void
+xfs_alloc_fix_len(
+	xfs_alloc_arg_t	*args)		/* allocation argument structure */
+{
+	xfs_extlen_t	k;
+	xfs_extlen_t	rlen;
+
+	ASSERT(args->mod < args->prod);
+	rlen = args->len;
+	ASSERT(rlen >= args->minlen);
+	ASSERT(rlen <= args->maxlen);
+	if (args->prod <= 1 || rlen < args->mod || rlen == args->maxlen ||
+	    (args->mod == 0 && rlen < args->prod))
+		return;
+	k = rlen % args->prod;
+	if (k == args->mod)
+		return;
+	if (k > args->mod) {
+		if ((int)(rlen = rlen - k - args->mod) < (int)args->minlen)
+			return;
+	} else {
+		if ((int)(rlen = rlen - args->prod - (args->mod - k)) <
+		    (int)args->minlen)
+			return;
+	}
+	ASSERT(rlen >= args->minlen);
+	ASSERT(rlen <= args->maxlen);
+	args->len = rlen;
+}
+
+/*
+ * Fix up length if there is too little space left in the a.g.
+ * Return 1 if ok, 0 if too little, should give up.
+ */
+STATIC int
+xfs_alloc_fix_minleft(
+	xfs_alloc_arg_t	*args)		/* allocation argument structure */
+{
+	xfs_agf_t	*agf;		/* a.g. freelist header */
+	int		diff;		/* free space difference */
+
+	if (args->minleft == 0)
+		return 1;
+	agf = XFS_BUF_TO_AGF(args->agbp);
+	diff = INT_GET(agf->agf_freeblks, ARCH_CONVERT)
+		+ INT_GET(agf->agf_flcount, ARCH_CONVERT)
+		- args->len - args->minleft;
+	if (diff >= 0)
+		return 1;
+	args->len += diff;		/* shrink the allocated space */
+	if (args->len >= args->minlen)
+		return 1;
+	args->agbno = NULLAGBLOCK;
+	return 0;
+}
+
+/*
+ * Update the two btrees, logically removing from freespace the extent
+ * starting at rbno, rlen blocks.  The extent is contained within the
+ * actual (current) free extent fbno for flen blocks.
+ * Flags are passed in indicating whether the cursors are set to the
+ * relevant records.
+ */
+STATIC int				/* error code */
+xfs_alloc_fixup_trees(
+	xfs_btree_cur_t	*cnt_cur,	/* cursor for by-size btree */
+	xfs_btree_cur_t	*bno_cur,	/* cursor for by-block btree */
+	xfs_agblock_t	fbno,		/* starting block of free extent */
+	xfs_extlen_t	flen,		/* length of free extent */
+	xfs_agblock_t	rbno,		/* starting block of returned extent */
+	xfs_extlen_t	rlen,		/* length of returned extent */
+	int		flags)		/* flags, XFSA_FIXUP_... */
+{
+	int		error;		/* error code */
+	int		i;		/* operation results */
+	xfs_agblock_t	nfbno1;		/* first new free startblock */
+	xfs_agblock_t	nfbno2;		/* second new free startblock */
+	xfs_extlen_t	nflen1=0;	/* first new free length */
+	xfs_extlen_t	nflen2=0;	/* second new free length */
+
+	/*
+	 * Look up the record in the by-size tree if necessary.
+	 */
+	if (flags & XFSA_FIXUP_CNT_OK) {
+#ifdef DEBUG
+		if ((error = xfs_alloc_get_rec(cnt_cur, &nfbno1, &nflen1, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(
+			i == 1 && nfbno1 == fbno && nflen1 == flen);
+#endif
+	} else {
+		if ((error = xfs_alloc_lookup_eq(cnt_cur, fbno, flen, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 1);
+	}
+	/*
+	 * Look up the record in the by-block tree if necessary.
+	 */
+	if (flags & XFSA_FIXUP_BNO_OK) {
+#ifdef DEBUG
+		if ((error = xfs_alloc_get_rec(bno_cur, &nfbno1, &nflen1, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(
+			i == 1 && nfbno1 == fbno && nflen1 == flen);
+#endif
+	} else {
+		if ((error = xfs_alloc_lookup_eq(bno_cur, fbno, flen, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 1);
+	}
+#ifdef DEBUG
+	{
+		xfs_alloc_block_t	*bnoblock;
+		xfs_alloc_block_t	*cntblock;
+
+		if (bno_cur->bc_nlevels == 1 &&
+		    cnt_cur->bc_nlevels == 1) {
+			bnoblock = XFS_BUF_TO_ALLOC_BLOCK(bno_cur->bc_bufs[0]);
+			cntblock = XFS_BUF_TO_ALLOC_BLOCK(cnt_cur->bc_bufs[0]);
+			XFS_WANT_CORRUPTED_RETURN(
+				INT_GET(bnoblock->bb_numrecs, ARCH_CONVERT) == INT_GET(cntblock->bb_numrecs, ARCH_CONVERT));
+		}
+	}
+#endif
+	/*
+	 * Deal with all four cases: the allocated record is contained
+	 * within the freespace record, so we can have new freespace
+	 * at either (or both) end, or no freespace remaining.
+	 */
+	if (rbno == fbno && rlen == flen)
+		nfbno1 = nfbno2 = NULLAGBLOCK;
+	else if (rbno == fbno) {
+		nfbno1 = rbno + rlen;
+		nflen1 = flen - rlen;
+		nfbno2 = NULLAGBLOCK;
+	} else if (rbno + rlen == fbno + flen) {
+		nfbno1 = fbno;
+		nflen1 = flen - rlen;
+		nfbno2 = NULLAGBLOCK;
+	} else {
+		nfbno1 = fbno;
+		nflen1 = rbno - fbno;
+		nfbno2 = rbno + rlen;
+		nflen2 = (fbno + flen) - nfbno2;
+	}
+	/*
+	 * Delete the entry from the by-size btree.
+	 */
+	if ((error = xfs_alloc_delete(cnt_cur, &i)))
+		return error;
+	XFS_WANT_CORRUPTED_RETURN(i == 1);
+	/*
+	 * Add new by-size btree entry(s).
+	 */
+	if (nfbno1 != NULLAGBLOCK) {
+		if ((error = xfs_alloc_lookup_eq(cnt_cur, nfbno1, nflen1, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 0);
+		if ((error = xfs_alloc_insert(cnt_cur, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 1);
+	}
+	if (nfbno2 != NULLAGBLOCK) {
+		if ((error = xfs_alloc_lookup_eq(cnt_cur, nfbno2, nflen2, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 0);
+		if ((error = xfs_alloc_insert(cnt_cur, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 1);
+	}
+	/*
+	 * Fix up the by-block btree entry(s).
+	 */
+	if (nfbno1 == NULLAGBLOCK) {
+		/*
+		 * No remaining freespace, just delete the by-block tree entry.
+		 */
+		if ((error = xfs_alloc_delete(bno_cur, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 1);
+	} else {
+		/*
+		 * Update the by-block entry to start later|be shorter.
+		 */
+		if ((error = xfs_alloc_update(bno_cur, nfbno1, nflen1)))
+			return error;
+	}
+	if (nfbno2 != NULLAGBLOCK) {
+		/*
+		 * 2 resulting free entries, need to add one.
+		 */
+		if ((error = xfs_alloc_lookup_eq(bno_cur, nfbno2, nflen2, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 0);
+		if ((error = xfs_alloc_insert(bno_cur, &i)))
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(i == 1);
+	}
+	return 0;
+}
+
+/*
+ * Read in the allocation group free block array.
+ */
+STATIC int				/* error */
+xfs_alloc_read_agfl(
+	xfs_mount_t	*mp,		/* mount point structure */
+	xfs_trans_t	*tp,		/* transaction pointer */
+	xfs_agnumber_t	agno,		/* allocation group number */
+	xfs_buf_t	**bpp)		/* buffer for the ag free block array */
+{
+	xfs_buf_t	*bp;		/* return value */
+	int		error;
+
+	ASSERT(agno != NULLAGNUMBER);
+	error = xfs_trans_read_buf(
+			mp, tp, mp->m_ddev_targp,
+			XFS_AG_DADDR(mp, agno, XFS_AGFL_DADDR(mp)),
+			XFS_FSS_TO_BB(mp, 1), 0, &bp);
+	if (error)
+		return error;
+	ASSERT(bp);
+	ASSERT(!XFS_BUF_GETERROR(bp));
+	XFS_BUF_SET_VTYPE_REF(bp, B_FS_AGFL, XFS_AGFL_REF);
+	*bpp = bp;
+	return 0;
+}
+
+#if defined(XFS_ALLOC_TRACE)
+/*
+ * Add an allocation trace entry for an alloc call.
+ */
+STATIC void
+xfs_alloc_trace_alloc(
+	char		*name,		/* function tag string */
+	char		*str,		/* additional string */
+	xfs_alloc_arg_t	*args,		/* allocation argument structure */
+	int		line)		/* source line number */
+{
+	ktrace_enter(xfs_alloc_trace_buf,
+		(void *)(__psint_t)(XFS_ALLOC_KTRACE_ALLOC | (line << 16)),
+		(void *)name,
+		(void *)str,
+		(void *)args->mp,
+		(void *)(__psunsigned_t)args->agno,
+		(void *)(__psunsigned_t)args->agbno,
+		(void *)(__psunsigned_t)args->minlen,
+		(void *)(__psunsigned_t)args->maxlen,
+		(void *)(__psunsigned_t)args->mod,
+		(void *)(__psunsigned_t)args->prod,
+		(void *)(__psunsigned_t)args->minleft,
+		(void *)(__psunsigned_t)args->total,
+		(void *)(__psunsigned_t)args->alignment,
+		(void *)(__psunsigned_t)args->len,
+		(void *)((((__psint_t)args->type) << 16) |
+			 (__psint_t)args->otype),
+		(void *)(__psint_t)((args->wasdel << 3) |
+				    (args->wasfromfl << 2) |
+				    (args->isfl << 1) |
+				    (args->userdata << 0)));
+}
+
+/*
+ * Add an allocation trace entry for a free call.
+ */
+STATIC void
+xfs_alloc_trace_free(
+	char		*name,		/* function tag string */
+	char		*str,		/* additional string */
+	xfs_mount_t	*mp,		/* file system mount point */
+	xfs_agnumber_t	agno,		/* allocation group number */
+	xfs_agblock_t	agbno,		/* a.g. relative block number */
+	xfs_extlen_t	len,		/* length of extent */
+	int		isfl,		/* set if is freelist allocation/free */
+	int		line)		/* source line number */
+{
+	ktrace_enter(xfs_alloc_trace_buf,
+		(void *)(__psint_t)(XFS_ALLOC_KTRACE_FREE | (line << 16)),
+		(void *)name,
+		(void *)str,
+		(void *)mp,
+		(void *)(__psunsigned_t)agno,
+		(void *)(__psunsigned_t)agbno,
+		(void *)(__psunsigned_t)len,
+		(void *)(__psint_t)isfl,
+		NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
+}
+
+/*
+ * Add an allocation trace entry for modifying an agf.
+ */
+STATIC void
+xfs_alloc_trace_modagf(
+	char		*name,		/* function tag string */
+	char		*str,		/* additional string */
+	xfs_mount_t	*mp,		/* file system mount point */
+	xfs_agf_t	*agf,		/* new agf value */
+	int		flags,		/* logging flags for agf */
+	int		line)		/* source line number */
+{
+	ktrace_enter(xfs_alloc_trace_buf,
+		(void *)(__psint_t)(XFS_ALLOC_KTRACE_MODAGF | (line << 16)),
+		(void *)name,
+		(void *)str,
+		(void *)mp,
+		(void *)(__psint_t)flags,
+		(void *)(__psunsigned_t)INT_GET(agf->agf_seqno, ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_length, ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_roots[XFS_BTNUM_BNO],
+						ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_roots[XFS_BTNUM_CNT],
+						ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_levels[XFS_BTNUM_BNO],
+						ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_levels[XFS_BTNUM_CNT],
+						ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_flfirst, ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_fllast, ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_flcount, ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_freeblks, ARCH_CONVERT),
+		(void *)(__psunsigned_t)INT_GET(agf->agf_longest, ARCH_CONVERT));
+}
+
+STATIC void
+xfs_alloc_trace_busy(
+	char		*name,		/* function tag string */
+	char		*str,		/* additional string */
+	xfs_mount_t	*mp,		/* file system mount poing */
+	xfs_agnumber_t	agno,		/* allocation group number */
+	xfs_agblock_t	agbno,		/* a.g. relative block number */
+	xfs_extlen_t	len,		/* length of extent */
+	int		slot,		/* perag Busy slot */
+	xfs_trans_t	*tp,
+	int		trtype,		/* type: add, delete, search */
+	int		line)		/* source line number */
+{
+	ktrace_enter(xfs_alloc_trace_buf,
+		(void *)(__psint_t)(trtype | (line << 16)),
+		(void *)name,
+		(void *)str,
+		(void *)mp,
+		(void *)(__psunsigned_t)agno,
+		(void *)(__psunsigned_t)agbno,
+		(void *)(__psunsigned_t)len,
+		(void *)(__psint_t)slot,
+		(void *)tp,
+		NULL, NULL, NULL, NULL, NULL, NULL, NULL);
+}
+#endif	/* XFS_ALLOC_TRACE */
+
+/*
+ * Allocation group level functions.
+ */
+
+/*
+ * Allocate a variable extent in the allocation group agno.
+ * Type and bno are used to determine where in the allocation group the
+ * extent will start.
+ * Extent's length (returned in *len) will be between minlen and maxlen,
+ * and of the form k * prod + mod unless there's nothing that large.
+ * Return the starting a.g. block, or NULLAGBLOCK if we can't do it.
+ */
+STATIC int			/* error */
+xfs_alloc_ag_vextent(
+	xfs_alloc_arg_t	*args)	/* argument structure for allocation */
+{
+	int		error=0;
+#ifdef XFS_ALLOC_TRACE
+	static char	fname[] = "xfs_alloc_ag_vextent";
+#endif
+
+	ASSERT(args->minlen > 0);
+	ASSERT(args->maxlen > 0);
+	ASSERT(args->minlen <= args->maxlen);
+	ASSERT(args->mod < args->prod);
+	ASSERT(args->alignment > 0);
+	/*
+	 * Branch to correct routine based on the type.
+	 */
+	args->wasfromfl = 0;
+	switch (args->type) {
+	case XFS_ALLOCTYPE_THIS_AG:
+		error = xfs_alloc_ag_vextent_size(args);
+		break;
+	case XFS_ALLOCTYPE_NEAR_BNO:
+		error = xfs_alloc_ag_vextent_near(args);
+		break;
+	case XFS_ALLOCTYPE_THIS_BNO:
+		error = xfs_alloc_ag_vextent_exact(args);
+		break;
+	default:
+		ASSERT(0);
+		/* NOTREACHED */
+	}
+	if (error)
+		return error;
+	/*
+	 * If the allocation worked, need to change the agf structure
+	 * (and log it), and the superblock.
+	 */
+	if (args->agbno != NULLAGBLOCK) {
+		xfs_agf_t	*agf;	/* allocation group freelist header */
+#ifdef XFS_ALLOC_TRACE
+		xfs_mount_t	*mp = args->mp;
+#endif
+		long		slen = (long)args->len;
+
+		ASSERT(args->len >= args->minlen && args->len <= args->maxlen);
+		ASSERT(!(args->wasfromfl) || !args->isfl);
+		ASSERT(args->agbno % args->alignment == 0);
+		if (!(args->wasfromfl)) {
+
+			agf = XFS_BUF_TO_AGF(args->agbp);
+			INT_MOD(agf->agf_freeblks, ARCH_CONVERT, -(args->len));
+			xfs_trans_agblocks_delta(args->tp,
+						 -((long)(args->len)));
+			args->pag->pagf_freeblks -= args->len;
+			ASSERT(INT_GET(agf->agf_freeblks, ARCH_CONVERT)
+				<= INT_GET(agf->agf_length, ARCH_CONVERT));
+			TRACE_MODAGF(NULL, agf, XFS_AGF_FREEBLKS);
+			xfs_alloc_log_agf(args->tp, args->agbp,
+						XFS_AGF_FREEBLKS);
+			/* search the busylist for these blocks */
+			xfs_alloc_search_busy(args->tp, args->agno,
+					args->agbno, args->len);
+		}
+		if (!args->isfl)
+			xfs_trans_mod_sb(args->tp,
+				args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS :
+					XFS_TRANS_SB_FDBLOCKS, -slen);
+		XFS_STATS_INC(xs_allocx);
+		XFS_STATS_ADD(xs_allocb, args->len);
+	}
+	return 0;
+}
+
+/*
+ * Allocate a variable extent at exactly agno/bno.
+ * Extent's length (returned in *len) will be between minlen and maxlen,
+ * and of the form k * prod + mod unless there's nothing that large.
+ * Return the starting a.g. block (bno), or NULLAGBLOCK if we can't do it.
+ */
+STATIC int			/* error */
+xfs_alloc_ag_vextent_exact(
+	xfs_alloc_arg_t	*args)	/* allocation argument structure */
+{
+	xfs_btree_cur_t	*bno_cur;/* by block-number btree cursor */
+	xfs_btree_cur_t	*cnt_cur;/* by count btree cursor */
+	xfs_agblock_t	end;	/* end of allocated extent */
+	int		error;
+	xfs_agblock_t	fbno;	/* start block of found extent */
+	xfs_agblock_t	fend;	/* end block of found extent */
+	xfs_extlen_t	flen;	/* length of found extent */
+#ifdef XFS_ALLOC_TRACE
+	static char	fname[] = "xfs_alloc_ag_vextent_exact";
+#endif
+	int		i;	/* success/failure of operation */
+	xfs_agblock_t	maxend;	/* end of maximal extent */
+	xfs_agblock_t	minend;	/* end of minimal extent */
+	xfs_extlen_t	rlen;	/* length of returned extent */
+
+	ASSERT(args->alignment == 1);
+	/*
+	 * Allocate/initialize a cursor for the by-number freespace btree.
+	 */
+	bno_cur = xfs_btree_init_cursor(args->mp, args->tp, args->agbp,
+		args->agno, XFS_BTNUM_BNO, NULL, 0);
+	/*
+	 * Lookup bno and minlen in the btree (minlen is irrelevant, really).
+	 * Look for the closest free block <= bno, it must contain bno
+	 * if any free block does.
+	 */
+	if ((error = xfs_alloc_lookup_le(bno_cur, args->agbno, args->minlen, &i)))
+		goto error0;
+	if (!i) {
+		/*
+		 * Didn't find it, return null.
+		 */
+		xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
+		args->agbno = NULLAGBLOCK;
+		return 0;
+	}
+	/*
+	 * Grab the freespace record.
+	 */
+	if ((error = xfs_alloc_get_rec(bno_cur, &fbno, &flen, &i)))
+		goto error0;
+	XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
+	ASSERT(fbno <= args->agbno);
+	minend = args->agbno + args->minlen;
+	maxend = args->agbno + args->maxlen;
+	fend = fbno + flen;
+	/*
+	 * Give up if the freespace isn't long enough for the minimum request.
+	 */
+	if (fend < minend) {
+		xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
+		args->agbno = NULLAGBLOCK;
+		return 0;
+	}
+	/*
+	 * End of extent will be smaller of the freespace end and the
+	 * maximal requested end.
+	 */
+	end = XFS_AGBLOCK_MIN(fend, maxend);
+	/*
+	 * Fix the length according to mod and prod if given.
+	 */
+	args->len = end - args->agbno;
+	xfs_alloc_fix_len(args);
+	if (!xfs_alloc_fix_minleft(args)) {
+		xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
+		return 0;
+	}
+	rlen = args->len;
+	ASSERT(args->agbno + rlen <= fend);
+	end = args->agbno + rlen;
+	/*
+	 * We are allocating agbno for rlen [agbno .. end]
+	 * Allocate/initialize a cursor for the by-size btree.
+	 */
+	cnt_cur = xfs_btree_init_cursor(args->mp, args->tp, args->agbp,
+		args->agno, XFS_BTNUM_CNT, NULL, 0);
+	ASSERT(args->agbno + args->len <=
+		INT_GET(XFS_BUF_TO_AGF(args->agbp)->agf_length,
+			ARCH_CONVERT));
+	if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen,
+			args->agbno, args->len, XFSA_FIXUP_BNO_OK))) {
+		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
+		goto error0;
+	}
+	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
+	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
+	TRACE_ALLOC("normal", args);
+	args->wasfromfl = 0;
+	return 0;
+
+error0:
+	xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
+	TRACE_ALLOC("error", args);
+	return error;
+}
+
+/*
+ * Allocate a variable extent near bno in the allocation group agno.
+ * Extent's length (returned in len) will be between minlen and maxlen,
+ * and of the form k * prod + mod unless there's nothing that large.
+ * Return the starting a.g. block, or NULLAGBLOCK if we can't do it.
+ */
+STATIC int				/* error */
+xfs_alloc_ag_vextent_near(
+	xfs_alloc_arg_t	*args)		/* allocation argument structure */
+{
+	xfs_btree_cur_t	*bno_cur_gt;	/* cursor for bno btree, right side */
+	xfs_btree_cur_t	*bno_cur_lt;	/* cursor for bno btree, left side */
+	xfs_btree_cur_t	*cnt_cur;	/* cursor for count btree */
+#ifdef XFS_ALLOC_TRACE
+	static char	fname[] = "xfs_alloc_ag_vextent_near";
+#endif
+	xfs_agblock_t	gtbno;		/* start bno of right side entry */
+	xfs_agblock_t	gtbnoa;		/* aligned ... */
+	xfs_extlen_t	gtdiff;		/* difference to right side entry */
+	xfs_extlen_t	gtlen;		/* length of right side entry */
+	xfs_extlen_t	gtlena;		/* aligned ... */
+	xfs_agblock_t	gtnew;		/* useful start bno of right side */
+	int		error;		/* error code */
+	int		i;		/* result code, temporary */
+	int		j;		/* result code, temporary */
+	xfs_agblock_t	ltbno;		/* start bno of left side entry */
+	xfs_agblock_t	ltbnoa;		/* aligned ... */
+	xfs_extlen_t	ltdiff;		/* difference to left side entry */
+	/*REFERENCED*/
+	xfs_agblock_t	ltend;		/* end bno of left side entry */
+	xfs_extlen_t	ltlen;		/* length of left side entry */
+	xfs_extlen_t	ltlena;		/* aligned ... */
+	xfs_agblock_t	ltnew;		/* useful start bno of left side */
+	xfs_extlen_t	rlen;		/* length of returned extent */
+#if defined(DEBUG) && defined(__KERNEL__)
+	/*
+	 * Randomly don't execute the first algorithm.
+	 */
+	int		dofirst;	/* set to do first algorithm */
+
+	dofirst = random() & 1;
+#endif
+	/*
+	 * Get a cursor for the by-size btree.
+	 */
+	cnt_cur = xfs_btree_init_cursor(args->mp, args->tp, args->agbp,
+		args->agno, XFS_BTNUM_CNT, NULL, 0);
+	ltlen = 0;
+	bno_cur_lt = bno_cur_gt = NULL;
+	/*
+	 * See if there are any free extents as big as maxlen.
+	 */
+	if ((error = xfs_alloc_lookup_ge(cnt_cur, 0, args->maxlen, &i)))
+		goto error0;
+	/*
+	 * If none, then pick up the last entry in the tree unless the
+	 * tree is empty.
+	 */
+	if (!i) {
+		if ((error = xfs_alloc_ag_vextent_small(args, cnt_cur, &ltbno,
+				&ltlen, &i)))
+			goto error0;
+		if (i == 0 || ltlen == 0) {
+			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
+			return 0;
+		}
+		ASSERT(i == 1);
+	}
+	args->wasfromfl = 0;
+	/*
+	 * First algorithm.
+	 * If the requested extent is large wrt the freespaces available
+	 * in this a.g., then the cursor will be pointing to a btree entry
+	 * near the right edge of the tree.  If it's in the last btree leaf
+	 * block, then we just examine all the entries in that block
+	 * that are big enough, and pick the best one.
+	 * This is written as a while loop so we can break out of it,
+	 * but we never loop back to the top.
+	 */
+	while (xfs_btree_islastblock(cnt_cur, 0)) {
+		xfs_extlen_t	bdiff;
+		int		besti=0;
+		xfs_extlen_t	blen=0;
+		xfs_agblock_t	bnew=0;
+
+#if defined(DEBUG) && defined(__KERNEL__)
+		if (!dofirst)
+			break;
+#endif
+		/*
+		 * Start from the entry that lookup found, sequence through
+		 * all larger free blocks.  If we're actually pointing at a
+		 * record smaller than maxlen, go to the start of this block,
+		 * and skip all those smaller than minlen.
+		 */
+		if (ltlen || args->alignment > 1) {
+			cnt_cur->bc_ptrs[0] = 1;
+			do {
+				if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno,
+						&ltlen, &i)))
+					goto error0;
+				XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
+				if (ltlen >= args->minlen)
+					break;
+				if ((error = xfs_alloc_increment(cnt_cur, 0, &i)))
+					goto error0;
+			} while (i);
+			ASSERT(ltlen >= args->minlen);
+			if (!i)
+				break;
+		}
+		i = cnt_cur->bc_ptrs[0];
+		for (j = 1, blen = 0, bdiff = 0;
+		     !error && j && (blen < args->maxlen || bdiff > 0);
+		     error = xfs_alloc_increment(cnt_cur, 0, &j)) {
+			/*
+			 * For each entry, decide if it's better than
+			 * the previous best entry.
+			 */
+			if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno, &ltlen, &i)))
+				goto error0;
+			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
+			if (!xfs_alloc_compute_aligned(ltbno, ltlen,
+					args->alignment, args->minlen,
+					&ltbnoa, &ltlena))
+				continue;
+			args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
+			xfs_alloc_fix_len(args);
+			ASSERT(args->len >= args->minlen);
+			if (args->len < blen)
+				continue;
+			ltdiff = xfs_alloc_compute_diff(args->agbno, args->len,
+				args->alignment, ltbno, ltlen, &ltnew);
+			if (ltnew != NULLAGBLOCK &&
+			    (args->len > blen || ltdiff < bdiff)) {
+				bdiff = ltdiff;
+				bnew = ltnew;
+				blen = args->len;
+				besti = cnt_cur->bc_ptrs[0];
+			}
+		}
+		/*
+		 * It didn't work.  We COULD be in a case where
+		 * there's a good record somewhere, so try again.
+		 */
+		if (blen == 0)
+			break;
+		/*
+		 * Point at the best entry, and retrieve it again.
+		 */
+		cnt_cur->bc_ptrs[0] = besti;
+		if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno, &ltlen, &i)))
+			goto error0;
+		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
+		ltend = ltbno + ltlen;
+		ASSERT(ltend <= INT_GET(XFS_BUF_TO_AGF(args->agbp)->agf_length,
+				ARCH_CONVERT));
+		args->len = blen;
+		if (!xfs_alloc_fix_minleft(args)) {
+			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
+			TRACE_ALLOC("nominleft", args);
+			return 0;
+		}
+		blen = args->len;
+		/*
+		 * We are allocating starting at bnew for blen blocks.
+		 */
+		args->agbno = bnew;
+		ASSERT(bnew >= ltbno);
+		ASSERT(bnew + blen <= ltend);
+		/*
+		 * Set up a cursor for the by-bno tree.
+		 */
+		bno_cur_lt = xfs_btree_init_cursor(args->mp, args->tp,
+			args->agbp, args->agno, XFS_BTNUM_BNO, NULL, 0);
+		/*
+		 * Fix up the btree entries.
+		 */
+		if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno,
+				ltlen, bnew, blen, XFSA_FIXUP_CNT_OK)))
+			goto error0;
+		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
+		xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_NOERROR);
+		TRACE_ALLOC("first", args);
+		return 0;
+	}
+	/*
+	 * Second algorithm.
+	 * Search in the by-bno tree to the left and to the right
+	 * simultaneously, until in each case we find a space big enough,
+	 * or run into the edge of the tree.  When we run into the edge,
+	 * we deallocate that cursor.
+	 * If both searches succeed, we compare the two spaces and pick
+	 * the better one.
+	 * With alignment, it's possible for both to fail; the upper
+	 * level algorithm that picks allocation groups for allocations
+	 * is not supposed to do this.
+	 */
+	/*
+	 * Allocate and initialize the cursor for the leftward search.
+	 */
+	bno_cur_lt = xfs_btree_init_cursor(args->mp, args->tp, args->agbp,
+		args->agno, XFS_BTNUM_BNO, NULL, 0);
+	/*
+	 * Lookup <= bno to find the leftward search's starting point.
+	 */
+	if ((error = xfs_alloc_lookup_le(bno_cur_lt, args->agbno, args->maxlen, &i)))
+		goto error0;
+	if (!i) {
+		/*
+		 * Didn't find anything; use this cursor for the rightward
+		 * search.
+		 */
+		bno_cur_gt = bno_cur_lt;
+		bno_cur_lt = NULL;
+	}
+	/*
+	 * Found something.  Duplicate the cursor for the rightward search.
+	 */
+	else if ((error = xfs_btree_dup_cursor(bno_cur_lt, &bno_cur_gt)))
+		goto error0;
+	/*
+	 * Increment the cursor, so we will point at the entry just right
+	 * of the leftward entry if any, or to the leftmost entry.
+	 */
+	if ((error = xfs_alloc_increment(bno_cur_gt, 0, &i)))
+		goto error0;
+	if (!i) {
+		/*
+		 * It failed, there are no rightward entries.
+		 */
+		xfs_btree_del_cursor(bno_cur_gt, XFS_BTREE_NOERROR);
+		bno_cur_gt = NULL;
+	}
+	/*
+	 * Loop going left with the leftward cursor, right with the
+	 * rightward cursor, until either both directions give up or
+	 * we find an entry at least as big as minlen.
+	 */
+	do {
+		if (bno_cur_lt) {
+			if ((error = xfs_alloc_get_rec(bno_cur_lt, &ltbno, &ltlen, &i)))
+				goto error0;
+			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
+			if (xfs_alloc_compute_aligned(ltbno, ltlen,
+					args->alignment, args->minlen,
+					&ltbnoa, &ltlena))
+				break;
+			if ((error = xfs_alloc_decrement(bno_cur_lt, 0, &i)))
+				goto error0;
+			if (!i) {
+				xfs_btree_del_cursor(bno_cur_lt,
+						     XFS_BTREE_NOERROR);
+				bno_cur_lt = NULL;
+			}
+		}
+		if (bno_cur_gt) {
+			if ((error = xfs_alloc_get_rec(bno_cur_gt, &gtbno, &gtlen, &i)))
+				goto error0;
+			XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
+			if (xfs_alloc_compute_aligned(gtbno, gtlen,
+					args->alignment, args->minlen,
+					&gtbnoa, &gtlena))
+				break;
+			if ((error = xfs_alloc_increment(bno_cur_gt, 0, &i)))
+				goto error0;
+			if (!i) {
+				xfs_btree_del_cursor(bno_cur_gt,
+						     XFS_BTREE_NOERROR);
+				bno_cur_gt = NULL;
+			}
+		}
+	} while (bno_cur_lt || bno_cur_gt);
+	/*
+	 * Got both cursors still active, need to find better entry.
+	 */
+	if (bno_cur_lt && bno_cur_gt) {
+		/*
+		 * Left side is long enough, look for a right side entry.
+		 */
+		if (ltlena >= args->minlen) {
+			/*
+			 * Fix up the length.
+			 */
+			args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
+			xfs_alloc_fix_len(args);
+			rlen = args->len;
+			ltdiff = xfs_alloc_compute_diff(args->agbno, rlen,
+				args->alignment, ltbno, ltlen, &ltnew);
+			/*
+			 * Not perfect.
+			 */
+			if (ltdiff) {
+				/*
+				 * Look until we find a better one, run out of
+				 * space, or run off the end.
+				 */
+				while (bno_cur_lt && bno_cur_gt) {
+					if ((error = xfs_alloc_get_rec(
+							bno_cur_gt, &gtbno,
+							&gtlen, &i)))
+						goto error0;
+					XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
+					xfs_alloc_compute_aligned(gtbno, gtlen,
+						args->alignment, args->minlen,
+						&gtbnoa, &gtlena);
+					/*
+					 * The left one is clearly better.
+					 */
+					if (gtbnoa >= args->agbno + ltdiff) {
+						xfs_btree_del_cursor(
+							bno_cur_gt,
+							XFS_BTREE_NOERROR);
+						bno_cur_gt = NULL;
+						break;
+					}
+					/*
+					 * If we reach a big enough entry,
+					 * compare the two and pick the best.
+					 */
+					if (gtlena >= args->minlen) {
+						args->len =
+							XFS_EXTLEN_MIN(gtlena,
+								args->maxlen);
+						xfs_alloc_fix_len(args);
+						rlen = args->len;
+						gtdiff = xfs_alloc_compute_diff(
+							args->agbno, rlen,
+							a