[for-linus][PATCH 8/9] eventfs: Do not treat events directory different than other directories

Steven Rostedt
2024-05-03T22:50:35Z

Treat the events directory the same as other directories when it comes to
permissions. The events directory was considered different because it's
dentry is persistent, whereas the other directory dentries are created
when accessed. But the way tracefs now does its ownership by using the
root dentry's permissions as the default permissions, the events directory
can get out of sync when a remount is performed setting the group and user
permissions.

Remove the special case for the events directory on setting the
attributes. This allows the updates caused by remount to work properly as
well as simplifies the code.

Link: https://lore.kernel.org/linux-trace-kernel/20240502200906.002923579@goodmis.org

Cc: stable@vger.kernel.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>
Fixes: 8186fff7ab649 ("tracefs/eventfs: Use root and instance inodes as default ownership")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
fs/tracefs/event_inode.c | 16 +---------------
1 file changed, 1 insertion(+), 15 deletions(-)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 9dacf65c0b6e..6e08405892ae 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -206,21 +206,7 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry,
* determined by the parent directory.
*/
if (dentry->d_inode->i_mode & S_IFDIR) {
- /*
- * The events directory dentry is never freed, unless its
- * part of an instance that is deleted. It's attr is the
- * default for its child files and directories.
- * Do not update it. It's not used for its own mode or ownership.
- */
- if (ei->is_events) {
- /* But it still needs to know if it was modified */
- if (iattr->ia_valid & ATTR_UID)
- ei->attr.mode |= EVENTFS_SAVE_UID;
- if (iattr->ia_valid & ATTR_GID)
- ei->attr.mode |= EVENTFS_SAVE_GID;
- } else {
- update_attr(&ei->attr, iattr);
- }
+ update_attr(&ei->attr, iattr);

} else {
name = dentry->d_name.name;
--
2.43.0