xfs: clean up xfs_alloc_ag_vextent_exact

Use a goto label to consolidate all block not found cases, and add a
tracepoint for them.  Also clean up a few whitespace issues.

Based on an earlier patch from Dave Chinner.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

fs/xfs/linux-2.6/xfs_trace.h

@@ -1422,6 +1422,7 @@ DEFINE_EVENT(xfs_alloc_class, name, \
 	TP_PROTO(struct xfs_alloc_arg *args), \
 	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_first);

fs/xfs/xfs_alloc.c

@@ -577,61 +577,58 @@ xfs_alloc_ag_vextent_exact(
 	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_allocbt_init_cursor(args->mp, args->tp, args->agbp,
-		args->agno, XFS_BTNUM_BNO);
+					  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.
 	 */
-	if ((error = xfs_alloc_lookup_le(bno_cur, args->agbno, args->minlen, &i)))
+	error = xfs_alloc_lookup_le(bno_cur, args->agbno, args->minlen, &i);
+	if (error)
 		goto error0;
-	if (!i) {
-		/*
-		 * Didn't find it, return null.
-		 */
-		xfs_btree_del_cursor(bno_cur, XFS_BTREE_NOERROR);
-		args->agbno = NULLAGBLOCK;
-		return 0;
-	}
+	if (!i)
+		goto not_found;
+
 	/*
 	 * Grab the freespace record.
 	 */
-	if ((error = xfs_alloc_get_rec(bno_cur, &fbno, &flen, &i)))
+	error = xfs_alloc_get_rec(bno_cur, &fbno, &flen, &i);
+	if (error)
 		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;
-	}
+	if (fend < minend)
+		goto not_found;
+
 	/*
 	 * 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.
 	 */
+	end = XFS_AGBLOCK_MIN(fend, maxend);
 	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;
-	}
+	if (!xfs_alloc_fix_minleft(args))
+		goto not_found;
+
 	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.
@@ -640,16 +637,25 @@ xfs_alloc_ag_vextent_exact(
 		args->agno, XFS_BTNUM_CNT);
 	ASSERT(args->agbno + args->len <=
 		be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
-	if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur, fbno, flen,
-			args->agbno, args->len, XFSA_FIXUP_BNO_OK))) {
+	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);
 
-	trace_xfs_alloc_exact_done(args);
 	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: