xfs: rework extent allocation

index a9ff3cf82cce..55eda416e18b 100644
@@ -1589,33 +1589,36 @@ xfs_alloc_ag_vextent_size(
  */
 STATIC int			/* error */
 xfs_alloc_ag_vextent_small(
-	xfs_alloc_arg_t	*args,	/* allocation argument structure */
-	xfs_btree_cur_t	*ccur,	/* by-size cursor */
-	xfs_agblock_t	*fbnop,	/* result block number */
-	xfs_extlen_t	*flenp,	/* result length */
-	int		*stat)	/* status: 0-freelist, 1-normal/none */
+	struct xfs_alloc_arg	*args,	/* allocation argument structure */
+	struct xfs_btree_cur	*ccur,	/* optional by-size cursor */
+	xfs_agblock_t		*fbnop,	/* result block number */
+	xfs_extlen_t		*flenp,	/* result length */
+	int			*stat)	/* status: 0-freelist, 1-normal/none */
 {
-	int		error;
-	xfs_agblock_t	fbno;
-	xfs_extlen_t	flen;
-	int		i;
+	int			error = 0;
+	xfs_agblock_t		fbno;
+	xfs_extlen_t		flen;
+	int			i = 0;
 
-	if ((error = xfs_btree_decrement(ccur, 0, &i)))
+	/*
+	 * If a cntbt cursor is provided, try to allocate the largest record in
+	 * the tree. Try the AGFL if the cntbt is empty, otherwise fail the
+	 * allocation. Make sure to respect minleft even when pulling from the
+	 * freelist.
+	 */
+	if (ccur)
+		error = xfs_btree_decrement(ccur, 0, &i);
+	if (error)
 		goto error0;
 	if (i) {
-		if ((error = xfs_alloc_get_rec(ccur, &fbno, &flen, &i)))
+		error = xfs_alloc_get_rec(ccur, &fbno, &flen, &i);
+		if (error)
 			goto error0;
 		XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
-	}
-	/*
-	 * Nothing in the btree, try the freelist.  Make sure
-	 * to respect minleft even when pulling from the
-	 * freelist.
-	 */
-	else if (args->minlen == 1 && args->alignment == 1 &&
-		 args->resv != XFS_AG_RESV_AGFL &&
-		 (be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_flcount)
-		  > args->minleft)) {
+	} else if (args->minlen == 1 && args->alignment == 1 &&
+		   args->resv != XFS_AG_RESV_AGFL &&
+		   (be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_flcount) >
+		    args->minleft)) {
 		error = xfs_alloc_get_freelist(args->tp, args->agbp, &fbno, 0);
 		if (error)
 			goto error0;

@@ -1661,14 +1664,11 @@ xfs_alloc_ag_vextent_small(
 		 */
 		else
 			flen = 0;
-	}
-	/*
-	 * Can't allocate from the freelist for some reason.
-	 */
-	else {
+	} else {
 		fbno = NULLAGBLOCK;
 		flen = 0;
 	}
+
 	/*
 	 * Can't do the allocation, give up.
 	 */

index 55eda416e18b..231e8ca5cce0 100644
@@ -1637,8 +1637,6 @@ xfs_alloc_ag_vextent_small(
 				}
 				xfs_trans_binval(args->tp, bp);
 			}
-			args->len = 1;
-			args->agbno = fbno;
 			XFS_WANT_CORRUPTED_GOTO(args->mp,
 				args->agbno + args->len <=
 				be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),

@@ -1656,6 +1654,8 @@ xfs_alloc_ag_vextent_small(
 			if (error)
 				goto error0;
 
+			*fbnop = args->agbno = fbno;
+			*flenp = args->len = 1;
 			*stat = 0;
 			return 0;
 		}

index 231e8ca5cce0..112411a46891 100644
@@ -39,7 +39,7 @@ struct workqueue_struct *xfs_alloc_wq;
 #define	XFSA_FIXUP_CNT_OK	2
 
 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_type(struct xfs_alloc_arg *);
 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 *);

@@ -728,7 +728,7 @@ xfs_alloc_ag_vextent(
 		error = xfs_alloc_ag_vextent_size(args);
 		break;
 	case XFS_ALLOCTYPE_NEAR_BNO:
-		error = xfs_alloc_ag_vextent_near(args);
+		error = xfs_alloc_ag_vextent_type(args);
 		break;
 	case XFS_ALLOCTYPE_THIS_BNO:
 		error = xfs_alloc_ag_vextent_exact(args);

@@ -887,499 +887,526 @@ xfs_alloc_ag_vextent_exact(
 }
 
 /*
- * Search the btree in a given direction via the search cursor and compare
- * the records found against the good extent we've already found.
+ * BLock allocation algorithm and data structures.
  */
-STATIC int
-xfs_alloc_find_best_extent(
-	struct xfs_alloc_arg	*args,	/* allocation argument structure */
-	struct xfs_btree_cur	**gcur,	/* good cursor */
-	struct xfs_btree_cur	**scur,	/* searching cursor */
-	xfs_agblock_t		gdiff,	/* difference for search comparison */
-	xfs_agblock_t		*sbno,	/* extent found by search */
-	xfs_extlen_t		*slen,	/* extent length */
-	xfs_agblock_t		*sbnoa,	/* aligned extent found by search */
-	xfs_extlen_t		*slena,	/* aligned extent length */
-	int			dir)	/* 0 = search right, 1 = search left */
+struct xfs_alloc_btree_cur {
+	struct xfs_btree_cur	*cur;		/* cursor */
+	bool			active;		/* cursor active flag */
+};
+
+struct xfs_alloc_cur {
+	struct xfs_alloc_btree_cur	cnt;	/* btree cursors */
+	struct xfs_alloc_btree_cur	bnolt;
+	struct xfs_alloc_btree_cur	bnogt;
+	xfs_extlen_t			cur_len;/* current search length */
+	xfs_agblock_t			rec_bno;/* extent startblock */
+	xfs_extlen_t			rec_len;/* extent length */
+	xfs_agblock_t			bno;	/* alloc bno */
+	xfs_extlen_t			len;	/* alloc len */
+	xfs_extlen_t			diff;	/* diff from search bno */
+	unsigned			busy_gen;/* busy state */
+	bool				busy;
+};
+
+/*
+ * Set up cursors, etc. in the extent allocation cursor. This function can be
+ * called multiple times to reset an initialized structure without having to
+ * reallocate cursors.
+ */
+static int
+xfs_alloc_cur_setup(
+	struct xfs_alloc_arg	*args,
+	struct xfs_alloc_cur	*acur)
 {
-	xfs_agblock_t		new;
-	xfs_agblock_t		sdiff;
+	xfs_agblock_t		agbno = 0;
 	int			error;
 	int			i;
-	unsigned		busy_gen;
 
-	/* The good extent is perfect, no need to  search. */
-	if (!gdiff)
-		goto out_use_good;
+	acur->cnt.active = acur->bnolt.active = acur->bnogt.active = false;
+	acur->cur_len = args->maxlen;
+	acur->rec_bno = 0;
+	acur->rec_len = 0;
+	acur->bno = 0;
+	acur->len = 0;
+	acur->diff = -1;
+	acur->busy = false;
+	acur->busy_gen = 0;
+
+	if (args->agbno != NULLAGBLOCK)
+		agbno = args->agbno;
 
 	/*
-	 * Look until we find a better one, run out of space or run off the end.
+	 * Initialize the cntbt cursor and determine whether to start the search
+	 * at maxlen or minlen. THIS_AG allocation mode expects the cursor at
+	 * the first available maxlen extent or at the end of the tree.
 	 */
-	do {
-		error = xfs_alloc_get_rec(*scur, sbno, slen, &i);
+	if (!acur->cnt.cur)
+		acur->cnt.cur = xfs_allocbt_init_cursor(args->mp, args->tp,
+					args->agbp, args->agno, XFS_BTNUM_CNT);
+	error = xfs_alloc_lookup_ge(acur->cnt.cur, agbno, acur->cur_len, &i);
+	if (!i) {
+		acur->cur_len = args->minlen;
+		error = xfs_alloc_lookup_ge(acur->cnt.cur, agbno, acur->cur_len,
+					    &i);
 		if (error)
-			goto error0;
-		XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
-		xfs_alloc_compute_aligned(args, *sbno, *slen,
-				sbnoa, slena, &busy_gen);
+			return error;
+	}
+	if (i)
+		acur->cnt.active = true;
+
+	/* init bnobt left/right search cursors */
+	if (!acur->bnolt.cur)
+		acur->bnolt.cur = xfs_allocbt_init_cursor(args->mp, args->tp,
+					args->agbp, args->agno, XFS_BTNUM_BNO);
+	error = xfs_alloc_lookup_le(acur->bnolt.cur, agbno, args->maxlen, &i);
+	if (error)
+		return error;
+	if (i)
+		acur->bnolt.active = true;
 
-		/*
-		 * The good extent is closer than this one.
-		 */
-		if (!dir) {
-			if (*sbnoa > args->max_agbno)
-				goto out_use_good;
-			if (*sbnoa >= args->agbno + gdiff)
-				goto out_use_good;
-		} else {
-			if (*sbnoa < args->min_agbno)
-				goto out_use_good;
-			if (*sbnoa <= args->agbno - gdiff)
-				goto out_use_good;
-		}
+	if (!acur->bnogt.cur)
+		acur->bnogt.cur = xfs_allocbt_init_cursor(args->mp, args->tp,
+					args->agbp, args->agno, XFS_BTNUM_BNO);
+	error = xfs_alloc_lookup_ge(acur->bnogt.cur, agbno, args->maxlen, &i);
+	if (error)
+		return error;
+	if (i)
+		acur->bnogt.active = true;
 
-		/*
-		 * Same distance, compare length and pick the best.
-		 */
-		if (*slena >= args->minlen) {
-			args->len = XFS_EXTLEN_MIN(*slena, args->maxlen);
-			xfs_alloc_fix_len(args);
+	return 0;
+}
 
-			sdiff = xfs_alloc_compute_diff(args->agbno, args->len,
-						       args->alignment,
-						       args->datatype, *sbnoa,
-						       *slena, &new);
+static void
+xfs_alloc_cur_close(
+	struct xfs_alloc_cur	*acur,
+	bool			error)
+{
+	int			cur_error = XFS_BTREE_NOERROR;
 
-			/*
-			 * Choose closer size and invalidate other cursor.
-			 */
-			if (sdiff < gdiff)
-				goto out_use_search;
-			goto out_use_good;
-		}
+	if (error)
+		cur_error = XFS_BTREE_ERROR;
+
+	if (acur->cnt.cur)
+		xfs_btree_del_cursor(acur->cnt.cur, cur_error);
+	if (acur->bnolt.cur)
+		xfs_btree_del_cursor(acur->bnolt.cur, cur_error);
+	if (acur->bnogt.cur)
+		xfs_btree_del_cursor(acur->bnogt.cur, cur_error);
+	acur->cnt.cur = acur->bnolt.cur = acur->bnogt.cur = NULL;
+}
 
-		if (!dir)
-			error = xfs_btree_increment(*scur, 0, &i);
-		else
-			error = xfs_btree_decrement(*scur, 0, &i);
-		if (error)
-			goto error0;
-	} while (i);
+/*
+ * Check an extent for allocation and track the best available candidate in the
+ * allocation structure. The cursor is deactivated if it has entered an out of
+ * range state based on allocation arguments. Optionally return the extent
+ * extent geometry and allocation status if requested by the caller.
+ */
+static int
+xfs_alloc_cur_check(
+	struct xfs_alloc_arg		*args,
+	struct xfs_alloc_cur		*acur,
+	struct xfs_alloc_btree_cur	*bcur,
+	xfs_agblock_t			*obno,
+	xfs_extlen_t			*olen,
+	bool				*new)
+{
+	int			error, i;
+	xfs_agblock_t		bno, bnoa, bnew;
+	xfs_extlen_t		len, lena, diff = -1;
+	bool			busy;
+	unsigned		busy_gen = 0;
+	bool			deactivate = false;
+	bool			isbnobt = bcur->cur->bc_btnum == XFS_BTNUM_BNO;
+
+	if (new)
+		*new = false;
+
+	error = xfs_alloc_get_rec(bcur->cur, &bno, &len, &i);
+	if (error)
+		return error;
+	XFS_WANT_CORRUPTED_RETURN(args->mp, i == 1);
+	if (obno)
+		*obno = bno;
+	if (olen)
+		*olen = len;
 
-out_use_good:
-	xfs_btree_del_cursor(*scur, XFS_BTREE_NOERROR);
-	*scur = NULL;
-	return 0;
+	/*
+	 * Check against minlen and then compute and check the aligned record.
+	 * If a cntbt record is out of size range (i.e., we're walking
+	 * backwards) or a bnobt record is out of locality range, deactivate the
+	 * cursor.
+	 */
+	if (len < args->minlen) {
+		deactivate = !isbnobt;
+		goto fail;
+	}
+
+	busy = xfs_alloc_compute_aligned(args, bno, len, &bnoa, &lena,
+					 &busy_gen);
+	acur->busy |= busy;
+	if (busy)
+		acur->busy_gen = busy_gen;
+	if (bnoa < args->min_agbno || bnoa > args->max_agbno) {
+		deactivate = isbnobt;
+		goto fail;
+	}
+	if (lena < args->minlen)
+		goto fail;
 
-out_use_search:
-	xfs_btree_del_cursor(*gcur, XFS_BTREE_NOERROR);
-	*gcur = NULL;
+	args->len = XFS_EXTLEN_MIN(lena, args->maxlen);
+	xfs_alloc_fix_len(args);
+	ASSERT(args->len >= args->minlen);
+	if (args->len < acur->len)
+		goto fail;
+
+	/*
+	 * We have an aligned record that satisfies minlen and beats the current
+	 * candidate length. The remaining locality checks are specific to near
+	 * allocation mode.
+	 */
+	ASSERT(args->type == XFS_ALLOCTYPE_NEAR_BNO);
+	diff = xfs_alloc_compute_diff(args->agbno, args->len,
+				      args->alignment, args->datatype,
+				      bnoa, lena, &bnew);
+	if (bnew == NULLAGBLOCK)
+		goto fail;
+	if (diff > acur->diff) {
+		/* deactivate bnobt cursor with worse locality */
+		deactivate = isbnobt;
+		goto fail;
+	}
+	if (args->len < acur->len)
+		goto fail;
+
+	/* found a new candidate extent */
+	acur->rec_bno = bno;
+	acur->rec_len = len;
+	acur->bno = bnew;
+	acur->len = args->len;
+	acur->diff = diff;
+	if (new)
+		*new = true;
+	trace_xfs_alloc_cur_new(args->mp, acur->bno, acur->len, acur->diff);
 	return 0;
 
-error0:
-	/* caller invalidates cursors */
-	return error;
+fail:
+	if (deactivate)
+		bcur->active = false;
+	return 0;
 }
 
 /*
- * 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.
+ * Complete an allocation of a candidate extent. Remove the extent from both
+ * trees and update the args structure.
  */
-STATIC int				/* error */
-xfs_alloc_ag_vextent_near(
-	xfs_alloc_arg_t	*args)		/* allocation argument structure */
+STATIC int
+xfs_alloc_cur_finish(
+	struct xfs_alloc_arg	*args,
+	struct xfs_alloc_cur	*acur)
 {
-	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 */
-	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 */
-	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 */
-	bool		busy;
-	unsigned	busy_gen;
-#ifdef DEBUG
-	/*
-	 * Randomly don't execute the first algorithm.
-	 */
-	int		dofirst;	/* set to do first algorithm */
+	int			error;
 
-	dofirst = prandom_u32() & 1;
-#endif
+	ASSERT(acur->len);
+	ASSERT(acur->cnt.cur && acur->bnolt.cur);
 
-	/* handle unitialized agbno range so caller doesn't have to */
-	if (!args->min_agbno && !args->max_agbno)
-		args->max_agbno = args->mp->m_sb.sb_agblocks - 1;
-	ASSERT(args->min_agbno <= args->max_agbno);
+	error = xfs_alloc_fixup_trees(acur->cnt.cur, acur->bnolt.cur,
+				      acur->rec_bno, acur->rec_len, acur->bno,
+				      acur->len, 0);
+	if (error)
+		return error;
 
-	/* clamp agbno to the range if it's outside */
-	if (args->agbno < args->min_agbno)
-		args->agbno = args->min_agbno;
-	if (args->agbno > args->max_agbno)
-		args->agbno = args->max_agbno;
+	args->agbno = acur->bno;
+	args->len = acur->len;
+	args->wasfromfl = 0;
 
-restart:
-	bno_cur_lt = NULL;
-	bno_cur_gt = NULL;
-	ltlen = 0;
-	gtlena = 0;
-	ltlena = 0;
-	busy = false;
+	trace_xfs_alloc_cur(args);
+	return 0;
+}
 
-	/*
-	 * Get a cursor for the by-size btree.
-	 */
-	cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
-		args->agno, XFS_BTNUM_CNT);
+/*
+ * Locality allocation lookup algorithm. This expects a cntbt cursor and uses
+ * bno optimized lookup to search for extents with ideal size and locality.
+ */
+STATIC int
+xfs_alloc_lookup_iter(
+	struct xfs_alloc_arg		*args,
+	struct xfs_alloc_cur		*acur,
+	struct xfs_alloc_btree_cur	*bcur)
+{
+	struct xfs_btree_cur	*cur = bcur->cur;
+	xfs_agblock_t		bno;
+	xfs_extlen_t		len, cur_len;
+	int			error;
+	int			i;
 
-	/*
-	 * 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);
-			trace_xfs_alloc_near_noentry(args);
-			return 0;
+	if (!bcur->active)
+		return 0;
+
+	/* locality optimized lookup */
+	cur_len = acur->cur_len;
+	error = xfs_alloc_lookup_ge(cur, args->agbno, cur_len, &i);
+	if (error)
+		return error;
+	if (i == 0) {
+		bcur->active = false;
+		return 0;
+	}
+
+	/* check the current record and update search length from it */
+	error = xfs_alloc_cur_check(args, acur, bcur, &bno, &len, NULL);
+	if (error)
+		return error;
+	ASSERT(len >= acur->cur_len);
+	acur->cur_len = len;
+
+	/*
+	 * We looked up the first record >= [agbno, len] above. The agbno is a
+	 * secondary key and so the current record may lie just before or after
+	 * agbno. If it is past agbno, check the previous record too so long as
+	 * the length matches as it may be closer. Don't check a smaller record
+	 * because that could deactivate our cursor.
+	 */
+	if (bno > args->agbno) {
+		error = xfs_btree_decrement(cur, 0, &i);
+		if (!error && i) {
+			error = xfs_alloc_get_rec(bcur->cur, &bno, &len, &i);
+			if (!error && i && len == acur->cur_len) {
+				error = xfs_alloc_cur_check(args, acur, bcur,
+							    NULL, NULL, NULL);
+			}
 		}
-		ASSERT(i == 1);
+		if (error)
+			return error;
 	}
-	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.
+	 * Increment the search key until we find at least one allocation
+	 * candidate or if the extent we found was larger. Otherwise, double the
+	 * search key to optimize the search. Efficiency is more important here
+	 * than absolute best locality.
 	 */
-	while (xfs_btree_islastblock(cnt_cur, 0)) {
-		xfs_extlen_t	bdiff;
-		int		besti=0;
-		xfs_extlen_t	blen=0;
-		xfs_agblock_t	bnew=0;
+	cur_len <<= 1;
+	if (!acur->len || acur->cur_len >= cur_len)
+		acur->cur_len++;
+	else
+		acur->cur_len = cur_len;
 
-#ifdef DEBUG
-		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(args->mp, i == 1, error0);
-				if (ltlen >= args->minlen)
-					break;
-				if ((error = xfs_btree_increment(cnt_cur, 0, &i)))
-					goto error0;
-			} while (i);
-			ASSERT(ltlen >= args->minlen);
-			if (!i)
+	return error;
+}
+
+/*
+ * Incremental lookup algorithm. Walk a btree in either direction looking for
+ * candidate extents. This works for either bnobt (locality allocation) or cntbt
+ * (by-size allocation) cursors.
+ */
+STATIC int
+xfs_alloc_walk_iter(
+	struct xfs_alloc_arg		*args,
+	struct xfs_alloc_cur		*acur,
+	struct xfs_alloc_btree_cur	*bcur,
+	bool				increment,
+	bool				findone,
+	int				iters,
+	int				*stat)
+{
+	struct xfs_btree_cur	*cur;
+	int			error;
+	int			i;
+	bool			found = false;
+
+	if (!bcur->active)
+		return 0;
+
+	*stat = 0;
+	cur = bcur->cur;
+	for (; iters > 0; iters--) {
+		error = xfs_alloc_cur_check(args, acur, bcur, NULL, NULL,
+					    &found);
+		if (error)
+			return error;
+		if (found) {
+			*stat = 1;
+			if (findone)
 				break;
 		}
-		i = cnt_cur->bc_ptrs[0];
-		for (j = 1, blen = 0, bdiff = 0;
-		     !error && j && (blen < args->maxlen || bdiff > 0);
-		     error = xfs_btree_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(args->mp, i == 1, error0);
-			busy = xfs_alloc_compute_aligned(args, ltbno, ltlen,
-					&ltbnoa, &ltlena, &busy_gen);
-			if (ltlena < args->minlen)
-				continue;
-			if (ltbnoa < args->min_agbno || ltbnoa > args->max_agbno)
-				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, args->datatype, ltbnoa,
-				ltlena, &ltnew);
-			if (ltnew != NULLAGBLOCK &&
-			    (args->len > blen || ltdiff < bdiff)) {
-				bdiff = ltdiff;
-				bnew = ltnew;
-				blen = args->len;
-				besti = cnt_cur->bc_ptrs[0];
-			}
+		if (!bcur->active)
+			break;
+
+		if (increment)
+			error = xfs_btree_increment(cur, 0, &i);
+		else
+			error = xfs_btree_decrement(cur, 0, &i);
+		if (error)
+			return error;
+		if (i == 0) {
+			bcur->active = false;
+			break;
 		}
+	}
+
+	return error;
+}
+
+/*
+ * High level locality allocation algorithm. Search the bnobt (left and right)
+ * in parallel with locality-optimized cntbt lookups to find an extent with
+ * ideal locality.
+ */
+STATIC int
+xfs_alloc_ag_vextent_cur(
+	struct xfs_alloc_arg	*args,
+	struct xfs_alloc_cur	*acur,
+	int			*stat)
+{
+	int				error;
+	int				i;
+	unsigned int			findbestcount;
+	struct xfs_alloc_btree_cur	*fbcur = NULL;
+	bool				fbinc = false;
+
+	ASSERT(acur->cnt.cur);
+	ASSERT(args->type != XFS_ALLOCTYPE_THIS_AG);
+	findbestcount = args->mp->m_alloc_mxr[0];
+	*stat = 0;
+
+	/* search as long as we have at least one active cursor */
+	while (acur->cnt.active || acur->bnolt.active || acur->bnogt.active) {
 		/*
-		 * It didn't work.  We COULD be in a case where
-		 * there's a good record somewhere, so try again.
+		 * Search the bnobt left and right. If either of these find a
+		 * suitable extent, we know we've found ideal locality. Do a
+		 * capped search in the opposite direction and we're done.
 		 */
-		if (blen == 0)
+		error = xfs_alloc_walk_iter(args, acur, &acur->bnolt, false,
+					    true, 1, &i);
+		if (error)
+			return error;
+		if (i) {
+			fbcur = &acur->bnogt;
+			fbinc = true;
 			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(args->mp, i == 1, error0);
-		ASSERT(ltbno + ltlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
-		args->len = blen;
+		}
 
-		/*
-		 * We are allocating starting at bnew for blen blocks.
-		 */
-		args->agbno = bnew;
-		ASSERT(bnew >= ltbno);
-		ASSERT(bnew + blen <= ltbno + ltlen);
-		/*
-		 * Set up a cursor for the by-bno tree.
-		 */
-		bno_cur_lt = xfs_allocbt_init_cursor(args->mp, args->tp,
-			args->agbp, args->agno, XFS_BTNUM_BNO);
-		/*
-		 * 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);
+		error = xfs_alloc_walk_iter(args, acur, &acur->bnogt, true,
+					    true, 1, &i);
+		if (error)
+			return error;
+		if (i) {
+			fbcur = &acur->bnolt;
+			break;
+		}
 
-		trace_xfs_alloc_near_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_allocbt_init_cursor(args->mp, args->tp, args->agbp,
-		args->agno, XFS_BTNUM_BNO);
-	/*
-	 * 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.
+		 * Search the cntbt for a maximum sized extent with ideal
+		 * locality. The lookup search terminates on reaching the end of
+		 * the cntbt. Break out of the loop if this occurs to throttle
+		 * the bnobt scans.
 		 */
-		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_btree_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(args->mp, i == 1, error0);
-			busy |= xfs_alloc_compute_aligned(args, ltbno, ltlen,
-					&ltbnoa, &ltlena, &busy_gen);
-			if (ltlena >= args->minlen && ltbnoa >= args->min_agbno)
-				break;
-			if ((error = xfs_btree_decrement(bno_cur_lt, 0, &i)))
-				goto error0;
-			if (!i || ltbnoa < args->min_agbno) {
-				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(args->mp, i == 1, error0);
-			busy |= xfs_alloc_compute_aligned(args, gtbno, gtlen,
-					&gtbnoa, &gtlena, &busy_gen);
-			if (gtlena >= args->minlen && gtbnoa <= args->max_agbno)
-				break;
-			if ((error = xfs_btree_increment(bno_cur_gt, 0, &i)))
-				goto error0;
-			if (!i || gtbnoa > args->max_agbno) {
-				xfs_btree_del_cursor(bno_cur_gt,
-						     XFS_BTREE_NOERROR);
-				bno_cur_gt = NULL;
+		error = xfs_alloc_lookup_iter(args, acur, &acur->cnt);
+		if (error)
+			return error;
+		if (!acur->cnt.active) {
+			if (!acur->len) {
+				fbcur = &acur->cnt;
+				error = xfs_btree_decrement(fbcur->cur, 0, &i);
+				if (error)
+					return error;
+				if (i)
+					fbcur->active = true;
 			}
+			break;
 		}
-	} while (bno_cur_lt || bno_cur_gt);
+	}
 
 	/*
-	 * Got both cursors still active, need to find better entry.
+	 * Perform a best-effort search in the opposite direction from a bnobt
+	 * allocation or backwards from the end of the cntbt if we couldn't find
+	 * a maxlen extent.
 	 */
-	if (bno_cur_lt && bno_cur_gt) {
-		if (ltlena >= args->minlen) {
-			/*
-			 * Left side is good, look for a right side entry.
-			 */
-			args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
-			xfs_alloc_fix_len(args);
-			ltdiff = xfs_alloc_compute_diff(args->agbno, args->len,
-				args->alignment, args->datatype, ltbnoa,
-				ltlena, &ltnew);
-
-			error = xfs_alloc_find_best_extent(args,
-						&bno_cur_lt, &bno_cur_gt,
-						ltdiff, &gtbno, &gtlen,
-						&gtbnoa, &gtlena,
-						0 /* search right */);
-		} else {
-			ASSERT(gtlena >= args->minlen);
-
-			/*
-			 * Right side is good, look for a left side entry.
-			 */
-			args->len = XFS_EXTLEN_MIN(gtlena, args->maxlen);
-			xfs_alloc_fix_len(args);
-			gtdiff = xfs_alloc_compute_diff(args->agbno, args->len,
-				args->alignment, args->datatype, gtbnoa,
-				gtlena, &gtnew);
-
-			error = xfs_alloc_find_best_extent(args,
-						&bno_cur_gt, &bno_cur_lt,
-						gtdiff, &ltbno, &ltlen,
-						&ltbnoa, &ltlena,
-						1 /* search left */);
-		}
-
+	if (fbcur) {
+		error = xfs_alloc_walk_iter(args, acur, fbcur, fbinc, true,
+					    findbestcount, &i);
 		if (error)
-			goto error0;
+			return error;
 	}
 
-	/*
-	 * If we couldn't get anything, give up.
-	 */
-	if (bno_cur_lt == NULL && bno_cur_gt == NULL) {
-		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
+	if (acur->len)
+		*stat = 1;
 
-		if (busy) {
-			trace_xfs_alloc_near_busy(args);
-			xfs_extent_busy_flush(args->mp, args->pag, busy_gen);
-			goto restart;
-		}
-		trace_xfs_alloc_size_neither(args);
-		args->agbno = NULLAGBLOCK;
-		return 0;
-	}
+	return error;
+}
 
-	/*
-	 * At this point we have selected a freespace entry, either to the
-	 * left or to the right.  If it's on the right, copy all the
-	 * useful variables to the "left" set so we only have one
-	 * copy of this code.
-	 */
-	if (bno_cur_gt) {
-		bno_cur_lt = bno_cur_gt;
-		bno_cur_gt = NULL;
-		ltbno = gtbno;
-		ltbnoa = gtbnoa;
-		ltlen = gtlen;
-		ltlena = gtlena;
-		j = 1;
-	} else
-		j = 0;
+/*
+ * 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_type(
+	xfs_alloc_arg_t	*args)		/* allocation argument structure */
+{
+	struct xfs_alloc_cur	acur = {0,};
+	int			error;		/* error code */
+	int			i;		/* result code, temporary */
+	xfs_agblock_t		bno;	      /* start bno of left side entry */
+	xfs_extlen_t		len;		/* length of left side entry */
+
+	/* handle unitialized agbno range so caller doesn't have to */
+	if (!args->min_agbno && !args->max_agbno)
+		args->max_agbno = args->mp->m_sb.sb_agblocks - 1;
+	ASSERT(args->min_agbno <= args->max_agbno);
+
+	/* clamp agbno to the range if it's outside */
+	if (args->agbno < args->min_agbno)
+		args->agbno = args->min_agbno;
+	if (args->agbno > args->max_agbno)
+		args->agbno = args->max_agbno;
+
+restart:
+	/* set up cursors and allocation tracking structure based on args */
+	error = xfs_alloc_cur_setup(args, &acur);
+	if (error)
+		goto out;
+
+	error = xfs_alloc_ag_vextent_cur(args, &acur, &i);
+	if (error)
+		goto out;
 
 	/*
-	 * Fix up the length and compute the useful address.
+	 * If we got an extent, finish the allocation. Otherwise check for busy
+	 * extents and retry or attempt a small allocation.
 	 */
-	args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
-	xfs_alloc_fix_len(args);
-	rlen = args->len;
-	(void)xfs_alloc_compute_diff(args->agbno, rlen, args->alignment,
-				     args->datatype, ltbnoa, ltlena, &ltnew);
-	ASSERT(ltnew >= ltbno);
-	ASSERT(ltnew + rlen <= ltbnoa + ltlena);
-	ASSERT(ltnew + rlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
-	ASSERT(ltnew >= args->min_agbno && ltnew <= args->max_agbno);
-	args->agbno = ltnew;
-
-	if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno, ltlen,
-			ltnew, rlen, XFSA_FIXUP_BNO_OK)))
-		goto error0;
+	if (i) {
+		error = xfs_alloc_cur_finish(args, &acur);
+		if (error)
+			goto out;
+	} else  {
+		if (acur.busy) {
+			trace_xfs_alloc_near_busy(args);
+			xfs_extent_busy_flush(args->mp, args->pag,
+					      acur.busy_gen);
+			goto restart;
+		}
 
-	if (j)
-		trace_xfs_alloc_near_greater(args);
-	else
-		trace_xfs_alloc_near_lesser(args);
+		/*
+		 * We get here if we can't satisfy minlen or the trees are
+		 * empty. We don't pass a cursor so this returns an AGFL block
+		 * (i == 0) or nothing.
+		 */
+		error = xfs_alloc_ag_vextent_small(args, NULL, &bno, &len, &i);
+		if (error)
+			goto out;
+		ASSERT(i == 0 || (i && len == 0));
+		trace_xfs_alloc_near_noentry(args);
 
-	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
-	xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_NOERROR);
-	return 0;
+		args->agbno = bno;
+		args->len = len;
+	}
 
- error0:
-	trace_xfs_alloc_near_error(args);
-	if (cnt_cur != NULL)
-		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
-	if (bno_cur_lt != NULL)
-		xfs_btree_del_cursor(bno_cur_lt, XFS_BTREE_ERROR);
-	if (bno_cur_gt != NULL)
-		xfs_btree_del_cursor(bno_cur_gt, XFS_BTREE_ERROR);
+out:
+	xfs_alloc_cur_close(&acur, error);
+	if (error)
+		trace_xfs_alloc_near_error(args);
 	return error;
 }
 

index 2464ea351f83..d08d747b51a8 100644
@@ -1636,13 +1636,10 @@ DEFINE_ALLOC_EVENT(xfs_alloc_exact_done);
 DEFINE_ALLOC_EVENT(xfs_alloc_exact_notfound);
 DEFINE_ALLOC_EVENT(xfs_alloc_exact_error);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_nominleft);
-DEFINE_ALLOC_EVENT(xfs_alloc_near_first);
-DEFINE_ALLOC_EVENT(xfs_alloc_near_greater);
-DEFINE_ALLOC_EVENT(xfs_alloc_near_lesser);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_error);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_noentry);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_busy);
-DEFINE_ALLOC_EVENT(xfs_alloc_size_neither);
+DEFINE_ALLOC_EVENT(xfs_alloc_cur);
 DEFINE_ALLOC_EVENT(xfs_alloc_size_noentry);
 DEFINE_ALLOC_EVENT(xfs_alloc_size_nominleft);
 DEFINE_ALLOC_EVENT(xfs_alloc_size_done);

@@ -1658,6 +1655,27 @@ DEFINE_ALLOC_EVENT(xfs_alloc_vextent_noagbp);
 DEFINE_ALLOC_EVENT(xfs_alloc_vextent_loopfailed);
 DEFINE_ALLOC_EVENT(xfs_alloc_vextent_allfailed);
 
+TRACE_EVENT(xfs_alloc_cur_new,
+	TP_PROTO(struct xfs_mount *mp, xfs_agblock_t bno, xfs_extlen_t len,
+		 xfs_extlen_t diff),
+	TP_ARGS(mp, bno, len, diff),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(xfs_agblock_t, bno)
+		__field(xfs_extlen_t, len)
+		__field(xfs_extlen_t, diff)
+	),
+	TP_fast_assign(
+		__entry->dev = mp->m_super->s_dev;
+		__entry->bno = bno;
+		__entry->len = len;
+		__entry->diff = diff;
+	),
+	TP_printk("dev %d:%d bno 0x%x len 0x%x diff 0x%x",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->bno, __entry->len, __entry->diff)
+)
+
 DECLARE_EVENT_CLASS(xfs_da_class,
 	TP_PROTO(struct xfs_da_args *args),
 	TP_ARGS(args),

index 112411a46891..9e22c6740ce3 100644
@@ -38,7 +38,6 @@ struct workqueue_struct *xfs_alloc_wq;
 #define	XFSA_FIXUP_BNO_OK	1
 #define	XFSA_FIXUP_CNT_OK	2
 
-STATIC int xfs_alloc_ag_vextent_exact(xfs_alloc_arg_t *);
 STATIC int xfs_alloc_ag_vextent_type(struct xfs_alloc_arg *);
 STATIC int xfs_alloc_ag_vextent_size(xfs_alloc_arg_t *);
 STATIC int xfs_alloc_ag_vextent_small(xfs_alloc_arg_t *,

@@ -728,10 +727,8 @@ xfs_alloc_ag_vextent(
 		error = xfs_alloc_ag_vextent_size(args);
 		break;
 	case XFS_ALLOCTYPE_NEAR_BNO:
-		error = xfs_alloc_ag_vextent_type(args);
-		break;
 	case XFS_ALLOCTYPE_THIS_BNO:
-		error = xfs_alloc_ag_vextent_exact(args);
+		error = xfs_alloc_ag_vextent_type(args);
 		break;
 	default:
 		ASSERT(0);

@@ -772,120 +769,6 @@ xfs_alloc_ag_vextent(
 	return error;
 }
 
-/*
- * 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 */
-	int		error;
-	xfs_agblock_t	fbno;	/* start block of found extent */
-	xfs_extlen_t	flen;	/* length of found extent */
-	xfs_agblock_t	tbno;	/* start block of busy extent */
-	xfs_extlen_t	tlen;	/* length of busy extent */
-	xfs_agblock_t	tend;	/* end block of busy extent */
-	int		i;	/* success/failure of operation */
-	unsigned	busy_gen;
-
-	ASSERT(args->alignment == 1);
-
-	/*
-	 * Allocate/initialize a cursor for the by-number freespace btree.
-	 */
-	bno_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
-					  args->agno, XFS_BTNUM_BNO);
-
-	/*
-	 * 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.
-	 */
-	error = xfs_alloc_lookup_le(bno_cur, args->agbno, args->minlen, &i);
-	if (error)
-		goto error0;
-	if (!i)
-		goto not_found;
-
-	/*
-	 * Grab the freespace record.
-	 */
-	error = xfs_alloc_get_rec(bno_cur, &fbno, &flen, &i);
-	if (error)
-		goto error0;
-	XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
-	ASSERT(fbno <= args->agbno);
-
-	/*
-	 * Check for overlapping busy extents.
-	 */
-	tbno = fbno;
-	tlen = flen;
-	xfs_extent_busy_trim(args, &tbno, &tlen, &busy_gen);
-
-	/*
-	 * Give up if the start of the extent is busy, or the freespace isn't
-	 * long enough for the minimum request.
-	 */
-	if (tbno > args->agbno)
-		goto not_found;
-	if (tlen < args->minlen)
-		goto not_found;
-	tend = tbno + tlen;
-	if (tend < args->agbno + args->minlen)
-		goto not_found;
-
-	/*
-	 * End of extent will be smaller of the freespace end and the
-	 * maximal requested end.
-	 *
-	 * Fix the length according to mod and prod if given.
-	 */
-	args->len = XFS_AGBLOCK_MIN(tend, args->agbno + args->maxlen)
-						- args->agbno;
-	xfs_alloc_fix_len(args);
-	ASSERT(args->agbno + args->len <= tend);
-
-	/*
-	 * We are allocating agbno for args->len
-	 * Allocate/initialize a cursor for the by-size btree.
-	 */
-	cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
-		args->agno, XFS_BTNUM_CNT);
-	ASSERT(args->agbno + args->len <=
-		be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
-	error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen, args->agbno,
-				      args->len, XFSA_FIXUP_BNO_OK);
-	if (error) {
-		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);
-
-	args->wasfromfl = 0;
-	trace_xfs_alloc_exact_done(args);
-	return 0;
-
-not_found:
-	/* Didn't find it, return null. */
-	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
-	args->agbno = NULLAGBLOCK;
-	trace_xfs_alloc_exact_notfound(args);
-	return 0;
-
-error0:
-	xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
-	trace_xfs_alloc_exact_error(args);
-	return error;
-}
-
 /*
  * BLock allocation algorithm and data structures.
  */

@@ -964,6 +847,15 @@ xfs_alloc_cur_setup(
 	if (i)
 		acur->bnolt.active = true;
 
+	/*
+	 * Exact allocation mode requires only one bnobt cursor.
+	 */
+	if (args->type == XFS_ALLOCTYPE_THIS_BNO) {
+		ASSERT(args->alignment == 1);
+		acur->cnt.active = false;
+		return 0;
+	}
+
 	if (!acur->bnogt.cur)
 		acur->bnogt.cur = xfs_allocbt_init_cursor(args->mp, args->tp,
 					args->agbp, args->agno, XFS_BTNUM_BNO);

@@ -1030,6 +922,12 @@ xfs_alloc_cur_check(
 	if (olen)
 		*olen = len;
 
+	/* exact allocs only check one record, mark the cursor inactive */
+	if (args->type == XFS_ALLOCTYPE_THIS_BNO) {
+		ASSERT(isbnobt);
+		bcur->active = false;
+	}
+
 	/*
 	 * Check against minlen and then compute and check the aligned record.
 	 * If a cntbt record is out of size range (i.e., we're walking

@@ -1061,22 +959,39 @@ xfs_alloc_cur_check(
 
 	/*
 	 * We have an aligned record that satisfies minlen and beats the current
-	 * candidate length. The remaining locality checks are specific to near
-	 * allocation mode.
+	 * candidate length. The remaining checks depend on allocation type.
+	 * Exact allocation checks one record and either succeeds or fails. Near
+	 * allocation computes and checks locality.  Near allocation computes
+	 * and checks locality.
 	 */
-	ASSERT(args->type == XFS_ALLOCTYPE_NEAR_BNO);
-	diff = xfs_alloc_compute_diff(args->agbno, args->len,
-				      args->alignment, args->datatype,
-				      bnoa, lena, &bnew);
-	if (bnew == NULLAGBLOCK)
-		goto fail;
-	if (diff > acur->diff) {
-		/* deactivate bnobt cursor with worse locality */
-		deactivate = isbnobt;
-		goto fail;
+	if (args->type == XFS_ALLOCTYPE_THIS_BNO) {
+		if ((bnoa > args->agbno) ||
+		    (bnoa + lena < args->agbno + args->minlen)) {
+			trace_xfs_alloc_exact_notfound(args);
+			goto fail;
+		}
+
+		bnew = args->agbno;
+		args->len = XFS_AGBLOCK_MIN(bnoa + lena,
+					    args->agbno + args->maxlen) -
+			    args->agbno;
+		diff = 0;
+		trace_xfs_alloc_exact_done(args);
+	} else {
+		ASSERT(args->type == XFS_ALLOCTYPE_NEAR_BNO);
+		diff = xfs_alloc_compute_diff(args->agbno, args->len,
+					      args->alignment, args->datatype,
+					      bnoa, lena, &bnew);
+		if (bnew == NULLAGBLOCK)
+			goto fail;
+		if (diff > acur->diff) {
+			/* deactivate bnobt cursor with worse locality */
+			deactivate = isbnobt;
+			goto fail;
+		}
+		if (args->len < acur->len)
+			goto fail;
 	}
-	if (args->len < acur->len)
-		goto fail;
 
 	/* found a new candidate extent */
 	acur->rec_bno = bno;

@@ -1280,6 +1195,8 @@ xfs_alloc_ag_vextent_cur(
 					    true, 1, &i);
 		if (error)
 			return error;
+		if (args->type == XFS_ALLOCTYPE_THIS_BNO)
+			break;
 		if (i) {
 			fbcur = &acur->bnogt;
 			fbinc = true;

index d08d747b51a8..aa3b6f181d08 100644
@@ -1634,7 +1634,6 @@ DEFINE_EVENT(xfs_alloc_class, name, \
 	TP_ARGS(args))
 DEFINE_ALLOC_EVENT(xfs_alloc_exact_done);
 DEFINE_ALLOC_EVENT(xfs_alloc_exact_notfound);
-DEFINE_ALLOC_EVENT(xfs_alloc_exact_error);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_nominleft);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_error);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_noentry);

index 9e22c6740ce3..0b121cb5ef3f 100644
@@ -39,7 +39,6 @@ struct workqueue_struct *xfs_alloc_wq;
 #define	XFSA_FIXUP_CNT_OK	2
 
 STATIC int xfs_alloc_ag_vextent_type(struct xfs_alloc_arg *);
-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 *);
 

@@ -724,8 +723,6 @@ xfs_alloc_ag_vextent(
 	args->wasfromfl = 0;
 	switch (args->type) {
 	case XFS_ALLOCTYPE_THIS_AG:
-		error = xfs_alloc_ag_vextent_size(args);
-		break;
 	case XFS_ALLOCTYPE_NEAR_BNO:
 	case XFS_ALLOCTYPE_THIS_BNO:
 		error = xfs_alloc_ag_vextent_type(args);

@@ -817,6 +814,8 @@ xfs_alloc_cur_setup(
 
 	if (args->agbno != NULLAGBLOCK)
 		agbno = args->agbno;
+	if (args->type == XFS_ALLOCTYPE_THIS_AG)
+		acur->cur_len += args->alignment - 1;
 
 	/*
 	 * Initialize the cntbt cursor and determine whether to start the search

@@ -827,7 +826,7 @@ xfs_alloc_cur_setup(
 		acur->cnt.cur = xfs_allocbt_init_cursor(args->mp, args->tp,
 					args->agbp, args->agno, XFS_BTNUM_CNT);
 	error = xfs_alloc_lookup_ge(acur->cnt.cur, agbno, acur->cur_len, &i);
-	if (!i) {
+	if (!i && args->type != XFS_ALLOCTYPE_THIS_AG) {
 		acur->cur_len = args->minlen;
 		error = xfs_alloc_lookup_ge(acur->cnt.cur, agbno, acur->cur_len,
 					    &i);

@@ -848,13 +847,15 @@ xfs_alloc_cur_setup(
 		acur->bnolt.active = true;
 
 	/*
-	 * Exact allocation mode requires only one bnobt cursor.
+	 * Exact allocation mode uses the bnobt, by-size allocation mode uses
+	 * the cntbt, either one requires only one bnobt cursor.
 	 */
 	if (args->type == XFS_ALLOCTYPE_THIS_BNO) {
 		ASSERT(args->alignment == 1);
 		acur->cnt.active = false;
 		return 0;
-	}
+	} else if (args->type == XFS_ALLOCTYPE_THIS_AG)
+		return 0;
 
 	if (!acur->bnogt.cur)
 		acur->bnogt.cur = xfs_allocbt_init_cursor(args->mp, args->tp,

@@ -960,9 +961,10 @@ xfs_alloc_cur_check(
 	/*
 	 * We have an aligned record that satisfies minlen and beats the current
 	 * candidate length. The remaining checks depend on allocation type.
-	 * Exact allocation checks one record and either succeeds or fails. Near
-	 * allocation computes and checks locality.  Near allocation computes
-	 * and checks locality.
+	 * Exact allocation checks one record and either succeeds or fails.
+	 * By-size allocation only needs to deactivate the cursor once we've
+	 * found a maxlen candidate. Near allocation computes and checks
+	 * locality. Near allocation computes and checks locality.
 	 */
 	if (args->type == XFS_ALLOCTYPE_THIS_BNO) {
 		if ((bnoa > args->agbno) ||

@@ -977,6 +979,12 @@ xfs_alloc_cur_check(
 			    args->agbno;
 		diff = 0;
 		trace_xfs_alloc_exact_done(args);
+	} else if (args->type == XFS_ALLOCTYPE_THIS_AG) {
+		if (lena >= args->maxlen) {
+			bcur->active = false;
+			trace_xfs_alloc_size_done(args);
+		}
+		bnew = bnoa;
 	} else {
 		ASSERT(args->type == XFS_ALLOCTYPE_NEAR_BNO);
 		diff = xfs_alloc_compute_diff(args->agbno, args->len,

@@ -1162,6 +1170,50 @@ xfs_alloc_walk_iter(
 	return error;
 }
 
+/*
+ * High level size allocation algorithm.
+ */
+STATIC int
+xfs_alloc_ag_vextent_size(
+	struct xfs_alloc_arg	*args,
+	struct xfs_alloc_cur	*acur,
+	int			*stat)
+{
+	int			error;
+	int			i;
+	bool			increment = true;
+
+	ASSERT(args->type == XFS_ALLOCTYPE_THIS_AG);
+	*stat = 0;
+
+	/*
+	 * The cursor either points at the first sufficiently sized extent for
+	 * an aligned maxlen allocation or off the edge of the tree. The only
+	 * way the former should fail is if the target extents are busy, so
+	 * return nothing and let the caller flush and retry. If the latter,
+	 * point the cursor at the last valid record and walk backwards from
+	 * there. There is still a chance to find a minlen extent.
+	 */
+	if (!acur->cnt.active) {
+		increment = false;
+		error = xfs_btree_decrement(acur->cnt.cur, 0, &i);
+		if (error)
+			return error;
+		if (i)
+			acur->cnt.active = true;
+	}
+
+	error = xfs_alloc_walk_iter(args, acur, &acur->cnt, increment, false,
+				    INT_MAX, &i);
+	if (error)
+		return error;
+
+	ASSERT(i == 1 || acur->busy || !increment);
+	if (acur->len)
+		*stat = 1;
+	return 0;
+}
+
 /*
  * High level locality allocation algorithm. Search the bnobt (left and right)
  * in parallel with locality-optimized cntbt lookups to find an extent with

@@ -1285,7 +1337,10 @@ xfs_alloc_ag_vextent_type(
 	if (error)
 		goto out;
 
-	error = xfs_alloc_ag_vextent_cur(args, &acur, &i);
+	if (args->type == XFS_ALLOCTYPE_THIS_AG)
+		error = xfs_alloc_ag_vextent_size(args, &acur, &i);
+	else
+		error = xfs_alloc_ag_vextent_cur(args, &acur, &i);
 	if (error)
 		goto out;
 

@@ -1327,205 +1382,6 @@ xfs_alloc_ag_vextent_type(
 	return error;
 }
 
-/*
- * Allocate a variable extent anywhere 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_size(
-	xfs_alloc_arg_t	*args)		/* allocation argument structure */
-{
-	xfs_btree_cur_t	*bno_cur;	/* cursor for bno btree */
-	xfs_btree_cur_t	*cnt_cur;	/* cursor for cnt btree */
-	int		error;		/* error result */
-	xfs_agblock_t	fbno;		/* start of found freespace */
-	xfs_extlen_t	flen;		/* length of found freespace */
-	int		i;		/* temp status variable */
-	xfs_agblock_t	rbno;		/* returned block number */
-	xfs_extlen_t	rlen;		/* length of returned extent */
-	bool		busy;
-	unsigned	busy_gen;
-
-restart:
-	/*
-	 * Allocate and initialize a cursor for the by-size btree.
-	 */
-	cnt_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
-		args->agno, XFS_BTNUM_CNT);
-	bno_cur = NULL;
-	busy = false;
-
-	/*
-	 * Look for an entry >= maxlen+alignment-1 blocks.
-	 */
-	if ((error = xfs_alloc_lookup_ge(cnt_cur, 0,
-			args->maxlen + args->alignment - 1, &i)))
-		goto error0;
-
-	/*
-	 * If none then we have to settle for a smaller extent. In the case that
-	 * there are no large extents, this will return the last entry in the
-	 * tree unless the tree is empty. In the case that there are only busy
-	 * large extents, this will return the largest small extent unless there
-	 * are no smaller extents available.
-	 */
-	if (!i) {
-		error = xfs_alloc_ag_vextent_small(args, cnt_cur,
-						   &fbno, &flen, &i);
-		if (error)
-			goto error0;
-		if (i == 0 || flen == 0) {
-			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
-			trace_xfs_alloc_size_noentry(args);
-			return 0;
-		}
-		ASSERT(i == 1);
-		busy = xfs_alloc_compute_aligned(args, fbno, flen, &rbno,
-				&rlen, &busy_gen);
-	} else {
-		/*
-		 * Search for a non-busy extent that is large enough.
-		 */
-		for (;;) {
-			error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen, &i);
-			if (error)
-				goto error0;
-			XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
-
-			busy = xfs_alloc_compute_aligned(args, fbno, flen,
-					&rbno, &rlen, &busy_gen);
-
-			if (rlen >= args->maxlen)
-				break;
-
-			error = xfs_btree_increment(cnt_cur, 0, &i);
-			if (error)
-				goto error0;
-			if (i == 0) {
-				/*
-				 * Our only valid extents must have been busy.
-				 * Make it unbusy by forcing the log out and
-				 * retrying.
-				 */
-				xfs_btree_del_cursor(cnt_cur,
-						     XFS_BTREE_NOERROR);
-				trace_xfs_alloc_size_busy(args);
-				xfs_extent_busy_flush(args->mp,
-							args->pag, busy_gen);
-				goto restart;
-			}
-		}
-	}
-
-	/*
-	 * In the first case above, we got the last entry in the
-	 * by-size btree.  Now we check to see if the space hits maxlen
-	 * once aligned; if not, we search left for something better.
-	 * This can't happen in the second case above.
-	 */
-	rlen = XFS_EXTLEN_MIN(args->maxlen, rlen);
-	XFS_WANT_CORRUPTED_GOTO(args->mp, rlen == 0 ||
-			(rlen <= flen && rbno + rlen <= fbno + flen), error0);
-	if (rlen < args->maxlen) {
-		xfs_agblock_t	bestfbno;
-		xfs_extlen_t	bestflen;
-		xfs_agblock_t	bestrbno;
-		xfs_extlen_t	bestrlen;
-
-		bestrlen = rlen;
-		bestrbno = rbno;
-		bestflen = flen;
-		bestfbno = fbno;
-		for (;;) {
-			if ((error = xfs_btree_decrement(cnt_cur, 0, &i)))
-				goto error0;
-			if (i == 0)
-				break;
-			if ((error = xfs_alloc_get_rec(cnt_cur, &fbno, &flen,
-					&i)))
-				goto error0;
-			XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
-			if (flen < bestrlen)
-				break;
-			busy = xfs_alloc_compute_aligned(args, fbno, flen,
-					&rbno, &rlen, &busy_gen);
-			rlen = XFS_EXTLEN_MIN(args->maxlen, rlen);
-			XFS_WANT_CORRUPTED_GOTO(args->mp, rlen == 0 ||
-				(rlen <= flen && rbno + rlen <= fbno + flen),
-				error0);
-			if (rlen > bestrlen) {
-				bestrlen = rlen;
-				bestrbno = rbno;
-				bestflen = flen;
-				bestfbno = fbno;
-				if (rlen == args->maxlen)
-					break;
-			}
-		}
-		if ((error = xfs_alloc_lookup_eq(cnt_cur, bestfbno, bestflen,
-				&i)))
-			goto error0;
-		XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
-		rlen = bestrlen;
-		rbno = bestrbno;
-		flen = bestflen;
-		fbno = bestfbno;
-	}
-	args->wasfromfl = 0;
-	/*
-	 * Fix up the length.
-	 */
-	args->len = rlen;
-	if (rlen < args->minlen) {
-		if (busy) {
-			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
-			trace_xfs_alloc_size_busy(args);
-			xfs_extent_busy_flush(args->mp, args->pag, busy_gen);
-			goto restart;
-		}
-		goto out_nominleft;
-	}
-	xfs_alloc_fix_len(args);
-
-	rlen = args->len;
-	XFS_WANT_CORRUPTED_GOTO(args->mp, rlen <= flen, error0);
-	/*
-	 * Allocate and initialize a cursor for the by-block tree.
-	 */
-	bno_cur = xfs_allocbt_init_cursor(args->mp, args->tp, args->agbp,
-		args->agno, XFS_BTNUM_BNO);
-	if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen,
-			rbno, rlen, XFSA_FIXUP_CNT_OK)))
-		goto error0;
-	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
-	xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
-	cnt_cur = bno_cur = NULL;
-	args->len = rlen;
-	args->agbno = rbno;
-	XFS_WANT_CORRUPTED_GOTO(args->mp,
-		args->agbno + args->len <=
-			be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),
-		error0);
-	trace_xfs_alloc_size_done(args);
-	return 0;
-
-error0:
-	trace_xfs_alloc_size_error(args);
-	if (cnt_cur)
-		xfs_btree_del_cursor(cnt_cur, XFS_BTREE_ERROR);
-	if (bno_cur)
-		xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
-	return error;
-
-out_nominleft:
-	xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
-	trace_xfs_alloc_size_nominleft(args);
-	args->agbno = NULLAGBLOCK;
-	return 0;
-}
-
 /*
  * Deal with the case where only small freespaces remain.
  * Either return the contents of the last freespace record,

index aa3b6f181d08..54be8e30ab11 100644
@@ -1639,11 +1639,7 @@ DEFINE_ALLOC_EVENT(xfs_alloc_near_error);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_noentry);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_busy);
 DEFINE_ALLOC_EVENT(xfs_alloc_cur);
-DEFINE_ALLOC_EVENT(xfs_alloc_size_noentry);
-DEFINE_ALLOC_EVENT(xfs_alloc_size_nominleft);
 DEFINE_ALLOC_EVENT(xfs_alloc_size_done);
-DEFINE_ALLOC_EVENT(xfs_alloc_size_error);
-DEFINE_ALLOC_EVENT(xfs_alloc_size_busy);
 DEFINE_ALLOC_EVENT(xfs_alloc_small_freelist);
 DEFINE_ALLOC_EVENT(xfs_alloc_small_notenough);
 DEFINE_ALLOC_EVENT(xfs_alloc_small_done);

index 0b121cb5ef3f..4f2fa44a1460 100644
@@ -39,8 +39,7 @@ struct workqueue_struct *xfs_alloc_wq;
 #define	XFSA_FIXUP_CNT_OK	2
 
 STATIC int xfs_alloc_ag_vextent_type(struct xfs_alloc_arg *);
-STATIC int xfs_alloc_ag_vextent_small(xfs_alloc_arg_t *,
-		xfs_btree_cur_t *, xfs_agblock_t *, xfs_extlen_t *, int *);
+STATIC int xfs_alloc_ag_vextent_agfl(struct xfs_alloc_arg *, xfs_agblock_t *);
 
 /*
  * Size of the AGFL.  For CRC-enabled filesystes we steal a couple of slots in

@@ -1318,7 +1317,6 @@ xfs_alloc_ag_vextent_type(
 	int			error;		/* error code */
 	int			i;		/* result code, temporary */
 	xfs_agblock_t		bno;	      /* start bno of left side entry */
-	xfs_extlen_t		len;		/* length of left side entry */
 
 	/* handle unitialized agbno range so caller doesn't have to */
 	if (!args->min_agbno && !args->max_agbno)

@@ -1365,14 +1363,16 @@ xfs_alloc_ag_vextent_type(
 		 * empty. We don't pass a cursor so this returns an AGFL block
 		 * (i == 0) or nothing.
 		 */
-		error = xfs_alloc_ag_vextent_small(args, NULL, &bno, &len, &i);
+		error = xfs_alloc_ag_vextent_agfl(args, &bno);
 		if (error)
 			goto out;
-		ASSERT(i == 0 || (i && len == 0));
 		trace_xfs_alloc_near_noentry(args);
 
 		args->agbno = bno;
-		args->len = len;
+		if (bno != NULLAGBLOCK) {
+			args->wasfromfl = 1;
+			args->len = 1;
+		}
 	}
 
 out:

@@ -1383,108 +1383,73 @@ xfs_alloc_ag_vextent_type(
 }
 
 /*
- * Deal with the case where only small freespaces remain.
- * Either return the contents of the last freespace record,
- * or allocate space from the freelist if there is nothing in the tree.
+ * Attempt to allocate from the AGFL. This is a last resort when no other free
+ * space is available.
  */
-STATIC int			/* error */
-xfs_alloc_ag_vextent_small(
+STATIC int
+xfs_alloc_ag_vextent_agfl(
 	struct xfs_alloc_arg	*args,	/* allocation argument structure */
-	struct xfs_btree_cur	*ccur,	/* optional by-size cursor */
-	xfs_agblock_t		*fbnop,	/* result block number */
-	xfs_extlen_t		*flenp,	/* result length */
-	int			*stat)	/* status: 0-freelist, 1-normal/none */
+	xfs_agblock_t		*fbnop)	/* result block number */
 {
 	int			error = 0;
 	xfs_agblock_t		fbno;
-	xfs_extlen_t		flen;
-	int			i = 0;
+
+	*fbnop = NULLAGBLOCK;
 
 	/*
-	 * If a cntbt cursor is provided, try to allocate the largest record in
-	 * the tree. Try the AGFL if the cntbt is empty, otherwise fail the
-	 * allocation. Make sure to respect minleft even when pulling from the
-	 * freelist.
+	 * The AGFL can only perform unaligned, single block allocations. Also
+	 * make sure this isn't an allocation for the AGFL itself and to respect
+	 * minleft before we take a block.
 	 */
-	if (ccur)
-		error = xfs_btree_decrement(ccur, 0, &i);
+	if (args->minlen != 1 || args->alignment != 1 ||
+	    args->resv == XFS_AG_RESV_AGFL ||
+	    (be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_flcount) <=
+	     args->minleft)) {
+		trace_xfs_alloc_agfl_notenough(args);
+		goto out;
+	}
+
+	error = xfs_alloc_get_freelist(args->tp, args->agbp, &fbno, 0);
 	if (error)
-		goto error0;
-	if (i) {
-		error = xfs_alloc_get_rec(ccur, &fbno, &flen, &i);
-		if (error)
-			goto error0;
-		XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
-	} else if (args->minlen == 1 && args->alignment == 1 &&
-		   args->resv != XFS_AG_RESV_AGFL &&
-		   (be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_flcount) >
-		    args->minleft)) {
-		error = xfs_alloc_get_freelist(args->tp, args->agbp, &fbno, 0);
-		if (error)
-			goto error0;
-		if (fbno != NULLAGBLOCK) {
-			xfs_extent_busy_reuse(args->mp, args->agno, fbno, 1,
-			      xfs_alloc_allow_busy_reuse(args->datatype));
+		goto out;
 
-			if (xfs_alloc_is_userdata(args->datatype)) {
-				xfs_buf_t	*bp;
+	if (fbno == NULLAGBLOCK)
+		goto out;
 
-				bp = xfs_btree_get_bufs(args->mp, args->tp,
-					args->agno, fbno, 0);
-				if (!bp) {
-					error = -EFSCORRUPTED;
-					goto error0;
-				}
-				xfs_trans_binval(args->tp, bp);
-			}
-			XFS_WANT_CORRUPTED_GOTO(args->mp,
-				args->agbno + args->len <=
-				be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),
-				error0);
-			args->wasfromfl = 1;
-			trace_xfs_alloc_small_freelist(args);
+	xfs_extent_busy_reuse(args->mp, args->agno, fbno, 1,
+			      xfs_alloc_allow_busy_reuse(args->datatype));
 
-			/*
-			 * If we're feeding an AGFL block to something that
-			 * doesn't live in the free space, we need to clear
-			 * out the OWN_AG rmap.
-			 */
-			error = xfs_rmap_free(args->tp, args->agbp, args->agno,
-					fbno, 1, &XFS_RMAP_OINFO_AG);
-			if (error)
-				goto error0;
+	if (xfs_alloc_is_userdata(args->datatype)) {
+		struct xfs_buf	*bp;
 
-			*fbnop = args->agbno = fbno;
-			*flenp = args->len = 1;
-			*stat = 0;
-			return 0;
+		bp = xfs_btree_get_bufs(args->mp, args->tp, args->agno, fbno,
+					0);
+		if (!bp) {
+			error = -EFSCORRUPTED;
+			goto out;
 		}
-		/*
-		 * Nothing in the freelist.
-		 */
-		else
-			flen = 0;
-	} else {
-		fbno = NULLAGBLOCK;
-		flen = 0;
+		xfs_trans_binval(args->tp, bp);
 	}
+	XFS_WANT_CORRUPTED_GOTO(args->mp,
+		fbno < be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),
+		out);
 
 	/*
-	 * Can't do the allocation, give up.
+	 * If we're feeding an AGFL block to something that doesn't live in the
+	 * free space, we need to clear out the OWN_AG rmap.
 	 */
-	if (flen < args->minlen) {
-		args->agbno = NULLAGBLOCK;
-		trace_xfs_alloc_small_notenough(args);
-		flen = 0;
-	}
+	error = xfs_rmap_free(args->tp, args->agbp, args->agno, fbno, 1,
+			      &XFS_RMAP_OINFO_AG);
+	if (error)
+		goto out;
+
 	*fbnop = fbno;
-	*flenp = flen;
-	*stat = 1;
-	trace_xfs_alloc_small_done(args);
-	return 0;
 
-error0:
-	trace_xfs_alloc_small_error(args);
+out:
+	if (error)
+		trace_xfs_alloc_agfl_error(args);
+	else
+		trace_xfs_alloc_agfl_done(args);
 	return error;
 }
 

index 54be8e30ab11..e0df6e8bc87a 100644
@@ -1640,10 +1640,9 @@ DEFINE_ALLOC_EVENT(xfs_alloc_near_noentry);
 DEFINE_ALLOC_EVENT(xfs_alloc_near_busy);
 DEFINE_ALLOC_EVENT(xfs_alloc_cur);
 DEFINE_ALLOC_EVENT(xfs_alloc_size_done);
-DEFINE_ALLOC_EVENT(xfs_alloc_small_freelist);
-DEFINE_ALLOC_EVENT(xfs_alloc_small_notenough);
-DEFINE_ALLOC_EVENT(xfs_alloc_small_done);
-DEFINE_ALLOC_EVENT(xfs_alloc_small_error);
+DEFINE_ALLOC_EVENT(xfs_alloc_agfl_notenough);
+DEFINE_ALLOC_EVENT(xfs_alloc_agfl_done);
+DEFINE_ALLOC_EVENT(xfs_alloc_agfl_error);
 DEFINE_ALLOC_EVENT(xfs_alloc_vextent_badargs);
 DEFINE_ALLOC_EVENT(xfs_alloc_vextent_nofix);
 DEFINE_ALLOC_EVENT(xfs_alloc_vextent_noagbp);