[PATCH v4 04/10] eventfs: Implement eventfs file add functions

[Ajay Kaher <akaher@vmware.com>]

Adding following function to eventfs to add files:

eventfs_add_top_file() adds the info of top file to
eventfs and dynamically create these files when they
are accessed.

eventfs_add_file() adds the info of nested files
to eventfs and dynamically create these files when
they are accessed.

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>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202305051619.9a469a9a-yujie.liu@intel.com
---
 fs/tracefs/event_inode.c | 84 ++++++++++++++++++++++++++++++++++++++++
 include/linux/tracefs.h  |  8 ++++
 2 files changed, 92 insertions(+)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 4e7a8eccaa0b..75dc8953d813 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -215,3 +215,87 @@ struct eventfs_file *eventfs_add_dir(const char *name,
 	mutex_unlock(&eventfs_mutex);
 	return ef;
 }
+
+/**
+ * eventfs_add_top_file - add event top file to list to create later
+ * @name: the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @parent: parent dentry for this file.
+ * @data: 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: 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 = eventfs_prepare_ef(name, mode, fop, NULL, data);
+
+	if (IS_ERR(ef))
+		return -ENOMEM;
+
+	mutex_lock(&eventfs_mutex);
+	list_add_tail(&ef->list, &ei->e_top_files);
+	ef->d_parent = parent;
+	mutex_unlock(&eventfs_mutex);
+	return 0;
+}
+
+/**
+ * eventfs_add_file - add eventfs file to list to create later
+ * @name: the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @ef_parent: parent eventfs_file for this file.
+ * @data: 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: 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 = eventfs_prepare_ef(name, mode, fop, NULL, data);
+	if (IS_ERR(ef))
+		return -ENOMEM;
+
+	mutex_lock(&eventfs_mutex);
+	list_add_tail(&ef->list, &ef_parent->ei->e_top_files);
+	ef->d_parent = ef_parent->dentry;
+	mutex_unlock(&eventfs_mutex);
+	return 0;
+}
diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h
index 432e5e6f7901..a51312ff803c 100644
--- a/include/linux/tracefs.h
+++ b/include/linux/tracefs.h
@@ -32,6 +32,14 @@ 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);
-- 
2.39.0