GFS2: Move readahead of metadata during deallocation into its own function

Move the recently added readahead of the indirect pointer
tree during deallocation into its own function in order
that we can use it elsewhere in the future. Also this
fixes the resetting of the "first" variable in the
original patch.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/bmap.c

@@ -269,6 +269,30 @@ static inline __be64 *metapointer(unsigned int height, const struct metapath *mp
 	return ((__be64 *)(bh->b_data + head_size)) + mp->mp_list[height];
 }
 
+static void gfs2_metapath_ra(struct gfs2_glock *gl,
+			     const struct buffer_head *bh, const __be64 *pos)
+{
+	struct buffer_head *rabh;
+	const __be64 *endp = (const __be64 *)(bh->b_data + bh->b_size);
+	const __be64 *t;
+
+	for (t = pos; t < endp; t++) {
+		if (!*t)
+			continue;
+
+		rabh = gfs2_getbuf(gl, be64_to_cpu(*t), CREATE);
+		if (trylock_buffer(rabh)) {
+			if (!buffer_uptodate(rabh)) {
+				rabh->b_end_io = end_buffer_read_sync;
+				submit_bh(READA | REQ_META, rabh);
+				continue;
+			}
+			unlock_buffer(rabh);
+		}
+		brelse(rabh);
+	}
+}
+
 /**
  * lookup_metapath - Walk the metadata tree to a specific point
  * @ip: The inode
@@ -843,7 +867,7 @@ static int recursive_scan(struct gfs2_inode *ip, struct buffer_head *dibh,
 {
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	struct buffer_head *bh = NULL;
-	__be64 *top, *bottom, *t2;
+	__be64 *top, *bottom;
 	u64 bn;
 	int error;
 	int mh_size = sizeof(struct gfs2_meta_header);
@@ -872,26 +896,9 @@ static int recursive_scan(struct gfs2_inode *ip, struct buffer_head *dibh,
 		goto out;
 
 	if (height < ip->i_height - 1) {
-		struct buffer_head *rabh;
 
-		for (t2 = top; t2 < bottom; t2++, first = 0) {
-			if (!*t2)
-				continue;
+		gfs2_metapath_ra(ip->i_gl, bh, top);
 
-			bn = be64_to_cpu(*t2);
-			rabh = gfs2_getbuf(ip->i_gl, bn, CREATE);
-			if (trylock_buffer(rabh)) {
-				if (buffer_uptodate(rabh)) {
-					unlock_buffer(rabh);
-					brelse(rabh);
-					continue;
-				}
-				rabh->b_end_io = end_buffer_read_sync;
-				submit_bh(READA | REQ_META, rabh);
-				continue;
-			}
-			brelse(rabh);
-		}
 		for (; top < bottom; top++, first = 0) {
 			if (!*top)
 				continue;