From 704f960dbee2f1634f4b4e16f208cb16eaf41c1e Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Date: Thu, 4 Jan 2024 16:57:14 -0500
Subject: [PATCH] eventfs: Read ei->entries before ei->children in
 eventfs_iterate()

In order to apply a shortcut to skip over the current ctx->pos
immediately, by using the ei->entries array, the reading of that array
should be first. Moving the array reading before the linked list reading
will make the shortcut change diff nicer to read.

Link: https://lore.kernel.org/all/CAHk-=wiKwDUDv3+jCsv-uacDcHDVTYsXtBR9=6sGM5mqX+DhOg@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240104220048.333115095@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 fs/tracefs/event_inode.c | 50 ++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index c73fb1f7ddbc..a1934e0eea3b 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -752,31 +752,6 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx)
 	 * Need to create the dentries and inodes to have a consistent
 	 * inode number.
 	 */
-	list_for_each_entry_srcu(ei_child, &ei->children, list,
-				 srcu_read_lock_held(&eventfs_srcu)) {
-
-		if (c > 0) {
-			c--;
-			continue;
-		}
-
-		ctx->pos++;
-
-		if (ei_child->is_freed)
-			continue;
-
-		name = ei_child->name;
-
-		dentry = create_dir_dentry(ei, ei_child, ei_dentry);
-		if (!dentry)
-			goto out_dec;
-		ino = dentry->d_inode->i_ino;
-		dput(dentry);
-
-		if (!dir_emit(ctx, name, strlen(name), ino, DT_DIR))
-			goto out_dec;
-	}
-
 	for (i = 0; i < ei->nr_entries; i++) {
 		void *cdata = ei->data;
 
@@ -810,6 +785,31 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx)
 		if (!dir_emit(ctx, name, strlen(name), ino, DT_REG))
 			goto out_dec;
 	}
+
+	list_for_each_entry_srcu(ei_child, &ei->children, list,
+				 srcu_read_lock_held(&eventfs_srcu)) {
+
+		if (c > 0) {
+			c--;
+			continue;
+		}
+
+		ctx->pos++;
+
+		if (ei_child->is_freed)
+			continue;
+
+		name = ei_child->name;
+
+		dentry = create_dir_dentry(ei, ei_child, ei_dentry);
+		if (!dentry)
+			goto out_dec;
+		ino = dentry->d_inode->i_ino;
+		dput(dentry);
+
+		if (!dir_emit(ctx, name, strlen(name), ino, DT_DIR))
+			goto out_dec;
+	}
 	ret = 1;
  out:
 	srcu_read_unlock(&eventfs_srcu, idx);