ext4: Add new tracepoints to track mballoc's buddy bitmap loads

Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/mballoc.c

@@ -890,6 +890,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
 			BUG_ON(incore == NULL);
 			mb_debug(1, "put buddy for group %u in page %lu/%x\n",
 				group, page->index, i * blocksize);
+			trace_ext4_mb_buddy_bitmap_load(sb, group);
 			grinfo = ext4_get_group_info(sb, group);
 			grinfo->bb_fragments = 0;
 			memset(grinfo->bb_counters, 0,
@@ -907,6 +908,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
 			BUG_ON(incore != NULL);
 			mb_debug(1, "put bitmap for group %u in page %lu/%x\n",
 				group, page->index, i * blocksize);
+			trace_ext4_mb_bitmap_load(sb, group);
 
 			/* see comments in ext4_mb_put_pa() */
 			ext4_lock_group(sb, group);

include/trace/events/ext4.h

@@ -974,6 +974,39 @@ TRACE_EVENT(ext4_da_release_space,
 		  __entry->reserved_meta_blocks, __entry->allocated_meta_blocks)
 );
 
+DECLARE_EVENT_CLASS(ext4__bitmap_load,
+	TP_PROTO(struct super_block *sb, unsigned long group),
+
+	TP_ARGS(sb, group),
+
+	TP_STRUCT__entry(
+		__field(	dev_t,	dev			)
+		__field(	__u32,	group			)
+
+	),
+
+	TP_fast_assign(
+		__entry->dev	= sb->s_dev;
+		__entry->group	= group;
+	),
+
+	TP_printk("dev %s group %u",
+		  jbd2_dev_to_name(__entry->dev), __entry->group)
+);
+
+DEFINE_EVENT(ext4__bitmap_load, ext4_mb_bitmap_load,
+
+	TP_PROTO(struct super_block *sb, unsigned long group),
+
+	TP_ARGS(sb, group)
+);
+
+DEFINE_EVENT(ext4__bitmap_load, ext4_mb_buddy_bitmap_load,
+
+	TP_PROTO(struct super_block *sb, unsigned long group),
+
+	TP_ARGS(sb, group)
+);
 
 #endif /* _TRACE_EXT4_H */