mm/khugepaged: refactor mm_khugepaged_scan_file tracepoint to remove filename from function call

Refactor the mm_khugepaged_scan_file tracepoint to move filename
dereference to the tracepoint definition, to maintain consistency with
other tracepoints[1].

[1]:lore.kernel.org/lkml/20221024111621.3ba17e2c@gandalf.local.home/

Link: https://lkml.kernel.org/r/20221026044524.54793-1-gautammenghani201@gmail.com
Fixes: d41fd201 ("mm/khugepaged: add tracepoint to hpage_collapse_scan_file()")
Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/trace/events/huge_memory.h

@@ -171,15 +171,15 @@ TRACE_EVENT(mm_collapse_huge_page_swapin,
 
 TRACE_EVENT(mm_khugepaged_scan_file,
 
-	TP_PROTO(struct mm_struct *mm, struct page *page, const char *filename,
+	TP_PROTO(struct mm_struct *mm, struct page *page, struct file *file,
 		 int present, int swap, int result),
 
-	TP_ARGS(mm, page, filename, present, swap, result),
+	TP_ARGS(mm, page, file, present, swap, result),
 
 	TP_STRUCT__entry(
 		__field(struct mm_struct *, mm)
 		__field(unsigned long, pfn)
-		__string(filename, filename)
+		__string(filename, file->f_path.dentry->d_iname)
 		__field(int, present)
 		__field(int, swap)
 		__field(int, result)
@@ -188,7 +188,7 @@ TRACE_EVENT(mm_khugepaged_scan_file,
 	TP_fast_assign(
 		__entry->mm = mm;
 		__entry->pfn = page ? page_to_pfn(page) : -1;
-		__assign_str(filename, filename);
+		__assign_str(filename, file->f_path.dentry->d_iname);
 		__entry->present = present;
 		__entry->swap = swap;
 		__entry->result = result;

mm/khugepaged.c

@@ -2153,8 +2153,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
 		}
 	}
 
-	trace_mm_khugepaged_scan_file(mm, page, file->f_path.dentry->d_iname,
-				      present, swap, result);
+	trace_mm_khugepaged_scan_file(mm, page, file, present, swap, result);
 	return result;
 }
 #else