From bddd4619e007edf17ea36c03384c203660af9fc1 Mon Sep 17 00:00:00 2001
From: ChenXiaoSong <chenxiaosong@chenxiaosong.com>
Date: Mon, 15 Apr 2024 08:44:27 +0000
Subject: [PATCH] nfs: add old '->iterate' directory operation for debug

Signed-off-by: ChenXiaoSong <chenxiaosong@chenxiaosong.com>
---
 fs/nfs/dir.c       |  2 +-
 fs/readdir.c       | 22 ++++++++++++++++++----
 include/linux/fs.h |  1 +
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ac505671efbd..f2ec9a59a50c 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -60,7 +60,7 @@ static void nfs_readdir_clear_array(struct folio *);
 const struct file_operations nfs_dir_operations = {
 	.llseek		= nfs_llseek_dir,
 	.read		= generic_read_dir,
-	.iterate_shared	= nfs_readdir,
+	.iterate	= nfs_readdir,
 	.open		= nfs_opendir,
 	.release	= nfs_closedir,
 	.fsync		= nfs_fsync_dir,
diff --git a/fs/readdir.c b/fs/readdir.c
index 278bc0254732..ac0b71fa1923 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -88,8 +88,11 @@ int iterate_dir(struct file *file, struct dir_context *ctx)
 {
 	struct inode *inode = file_inode(file);
 	int res = -ENOTDIR;
+	bool shared = true;
 
-	if (!file->f_op->iterate_shared)
+	if (file->f_op->iterate)
+		shared = false;
+	else if (!file->f_op->iterate_shared)
 		goto out;
 
 	res = security_file_permission(file, MAY_READ);
@@ -100,19 +103,30 @@ int iterate_dir(struct file *file, struct dir_context *ctx)
 	if (res)
 		goto out;
 
-	res = down_read_killable(&inode->i_rwsem);
+	if (shared)
+		res = down_read_killable(&inode->i_rwsem);
+	else
+		res = down_write_killable(&inode->i_rwsem);
+
 	if (res)
 		goto out;
 
 	res = -ENOENT;
 	if (!IS_DEADDIR(inode)) {
 		ctx->pos = file->f_pos;
-		res = file->f_op->iterate_shared(file, ctx);
+		if (shared)
+			res = file->f_op->iterate_shared(file, ctx);
+		else
+			res = file->f_op->iterate(file, ctx);
 		file->f_pos = ctx->pos;
 		fsnotify_access(file);
 		file_accessed(file);
 	}
-	inode_unlock_shared(inode);
+	if (shared)
+		inode_unlock_shared(inode);
+	else
+		inode_unlock(inode);
+
 out:
 	return res;
 }
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 00fc429b0af0..dcee19443b75 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2011,6 +2011,7 @@ struct file_operations {
 	int (*iopoll)(struct kiocb *kiocb, struct io_comp_batch *,
 			unsigned int flags);
 	int (*iterate_shared) (struct file *, struct dir_context *);
+	int (*iterate) (struct file *, struct dir_context *);
 	__poll_t (*poll) (struct file *, struct poll_table_struct *);
 	long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
 	long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
-- 
2.34.1