From:   Ajay Kaher <akaher@vmware.com>
To:     rostedt@goodmis.org, mhiramat@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
        chinglinyu@google.com, namit@vmware.com, srivatsab@vmware.com,
        srivatsa@csail.mit.edu, amakhalov@vmware.com,
        vsirnapalli@vmware.com, tkundu@vmware.com, er.ajay.kaher@gmail.com,
        Ajay Kaher <akaher@vmware.com>
Subject: [PATCH 3/8] eventfs: adding eventfs file add functions
Date:   Sun, 22 Jan 2023 22:37:02 +0530
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Adding following function to eventfs to add files:

eventfs_add_top_file() will add the info of top file
to eventfs and dynamically create these files as and
when required.

eventfs_add_file() will add the info of nested files
to eventfs and dynamically create these dir as and
when required.

Signed-off-by: Ajay Kaher <akaher@vmware.com>
Co-developed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Ching-lin Yu <chinglinyu@google.com>
---
 fs/tracefs/event_inode.c | 108 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/tracefs.h  |   8 ++++
 2 files changed, 116 insertions(+)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index ef3b435..e479712 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -171,3 +171,111 @@ struct eventfs_file *eventfs_add_dir(const char *name, struct eventfs_file *ef_p
 	list_add_tail(&ef->list, &ef_parent->ei->e_top_files);
 	return ef;
 }
+
+/**
+ * eventfs_add_top_file - add event top file to list to create later
+ * @name: a pointer to a string containing the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @parent: a pointer to the parent dentry for this file.  This should be a
+ *          directory dentry if set.  If this parameter is NULL, then the
+ *          file will be created in the root of the tracefs filesystem.
+ * @data: a pointer to something that the caller will want to get to later
+ *        on.  The inode.i_private pointer will point to this value on
+ *        the open() call.
+ * @fop: a pointer to a struct file_operations that should be used for
+ *        this file.
+ *
+ * This function adds top files of event dir to list.
+ * And all these files are created on the fly when they are looked up,
+ * and the dentry and inodes will be removed when they are done.
+ */
+int eventfs_add_top_file(const char *name, umode_t mode,
+			 struct dentry *parent, void *data,
+			 const struct file_operations *fop)
+{
+	struct tracefs_inode *ti;
+	struct eventfs_inode *ei;
+	struct eventfs_file *ef;
+
+	if (!parent)
+		return -EINVAL;
+
+	if (!(mode & S_IFMT))
+		mode |= S_IFREG;
+
+	if (!parent->d_inode)
+		return -EINVAL;
+
+	ti = get_tracefs(parent->d_inode);
+	if (!(ti->flags & TRACEFS_EVENT_INODE))
+		return -EINVAL;
+
+	ei = ti->private;
+	ef = kzalloc(sizeof(*ef), GFP_KERNEL);
+	if (!ef)
+		return -ENOMEM;
+
+	ef->name = kstrdup(name, GFP_KERNEL);
+	if (!ef->name) {
+		kfree(ef);
+		return -ENOMEM;
+	}
+
+	ef->mode = mode;
+	ef->data = data;
+	ef->fop = fop;
+	ef->dentry = NULL;
+	ef->ei = NULL;
+	ef->created = false;
+	ef->d_parent = parent;
+	list_add_tail(&ef->list, &ei->e_top_files);
+	return 0;
+}
+
+/**
+ * eventfs_add_file - add eventfs file to list to create later
+ * @name: a pointer to a string containing the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @ef_parent: a pointer to the parent eventfs_file for this file.
+ * @data: a pointer to something that the caller will want to get to later
+ *        on.  The inode.i_private pointer will point to this value on
+ *        the open() call.
+ * @fop: a pointer to a struct file_operations that should be used for
+ *        this file.
+ *
+ * This function adds top files of event dir to list.
+ * And all these files are created on the fly when they are looked up,
+ * and the dentry and inodes will be removed when they are done.
+ */
+int eventfs_add_file(const char *name, umode_t mode,
+		     struct eventfs_file *ef_parent,
+		     void *data,
+		     const struct file_operations *fop)
+{
+	struct eventfs_file *ef;
+
+	if (!ef_parent)
+		return -EINVAL;
+
+	if (!(mode & S_IFMT))
+		mode |= S_IFREG;
+
+	ef = kzalloc(sizeof(*ef), GFP_KERNEL);
+	if (!ef)
+		return -ENOMEM;
+
+	ef->name = kstrdup(name, GFP_KERNEL);
+	if (!ef->name) {
+		kfree(ef);
+		return -ENOMEM;
+	}
+
+	ef->mode = mode;
+	ef->data = data;
+	ef->fop = fop;
+	ef->dentry = NULL;
+	ef->ei = NULL;
+	ef->created = false;
+	list_add_tail(&ef->list, &ef_parent->ei->e_top_files);
+	return 0;
+}
diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h
index 6983409..7d390d2 100644
--- a/include/linux/tracefs.h
+++ b/include/linux/tracefs.h
@@ -47,6 +47,14 @@ struct eventfs_file *eventfs_add_subsystem_dir(const char *name,
 struct eventfs_file *eventfs_add_dir(const char *name,
 				     struct eventfs_file *ef_parent);
 
+int eventfs_add_file(const char *name, umode_t mode,
+		     struct eventfs_file *ef_parent, void *data,
+		     const struct file_operations *fops);
+
+int eventfs_add_top_file(const char *name, umode_t mode,
+			 struct dentry *parent, void *data,
+			 const struct file_operations *fops);
+
 struct dentry *tracefs_create_file(const char *name, umode_t mode,
 				   struct dentry *parent, void *data,
 				   const struct file_operations *fops);
-- 
2.7.4