---

yaml
---
r: 269916
b: refs/heads/master
c: 3815832
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ddc3415aba1cb2f86d1fcad720cea834ee178f54
+refs/heads/master: 3815832a2aa4df9815d15dac05227e0c8551833f

trunk/fs/xfs/xfs_buf.c

@@ -477,8 +477,6 @@ _xfs_buf_find(
 
 	/* No match found */
 	if (new_bp) {
-		_xfs_buf_initialize(new_bp, btp, range_base,
-				range_length, flags);
 		rb_link_node(&new_bp->b_rbnode, parent, rbp);
 		rb_insert_color(&new_bp->b_rbnode, &pag->pag_buf_tree);
 		/* the buffer keeps the perag reference until it is freed */
@@ -521,35 +519,53 @@ _xfs_buf_find(
 }
 
 /*
- *	Assembles a buffer covering the specified range.
- *	Storage in memory for all portions of the buffer will be allocated,
- *	although backing storage may not be.
+ * Assembles a buffer covering the specified range. The code is optimised for
+ * cache hits, as metadata intensive workloads will see 3 orders of magnitude
+ * more hits than misses.
  */
-xfs_buf_t *
+struct xfs_buf *
 xfs_buf_get(
 	xfs_buftarg_t		*target,/* target for buffer		*/
 	xfs_off_t		ioff,	/* starting offset of range	*/
 	size_t			isize,	/* length of range		*/
 	xfs_buf_flags_t		flags)
 {
-	xfs_buf_t		*bp, *new_bp;
+	struct xfs_buf		*bp;
+	struct xfs_buf		*new_bp;
 	int			error = 0;
 
+	bp = _xfs_buf_find(target, ioff, isize, flags, NULL);
+	if (likely(bp))
+		goto found;
+
 	new_bp = xfs_buf_allocate(flags);
 	if (unlikely(!new_bp))
 		return NULL;
 
+	_xfs_buf_initialize(new_bp, target,
+			    ioff << BBSHIFT, isize << BBSHIFT, flags);
+
 	bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
+	if (!bp) {
+		xfs_buf_deallocate(new_bp);
+		return NULL;
+	}
+
 	if (bp == new_bp) {
 		error = xfs_buf_allocate_memory(bp, flags);
 		if (error)
 			goto no_buffer;
-	} else {
+	} else
 		xfs_buf_deallocate(new_bp);
-		if (unlikely(bp == NULL))
-			return NULL;
-	}
 
+	/*
+	 * Now we have a workable buffer, fill in the block number so
+	 * that we can do IO on it.
+	 */
+	bp->b_bn = ioff;
+	bp->b_count_desired = bp->b_buffer_length;
+
+found:
 	if (!(bp->b_flags & XBF_MAPPED)) {
 		error = _xfs_buf_map_pages(bp, flags);
 		if (unlikely(error)) {
@@ -560,18 +576,10 @@ xfs_buf_get(
 	}
 
 	XFS_STATS_INC(xb_get);
-
-	/*
-	 * Always fill in the block number now, the mapped cases can do
-	 * their own overlay of this later.
-	 */
-	bp->b_bn = ioff;
-	bp->b_count_desired = bp->b_buffer_length;
-
 	trace_xfs_buf_get(bp, flags, _RET_IP_);
 	return bp;
 
- no_buffer:
+no_buffer:
 	if (flags & (XBF_LOCK | XBF_TRYLOCK))
 		xfs_buf_unlock(bp);
 	xfs_buf_rele(bp);