Re: [PATCH 2/2] tracefs: Don't overlay 'struct inode'
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2024-08-07 13:45:00
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On Wed, Aug 07, 2024 at 09:35:45AM -0400, Steven Rostedt wrote:
quoted hunk ↗ jump to hunk
Perhaps:diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index f704d8348357..ab6d6c3d835d 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h@@ -10,12 +10,12 @@ enum { }; struct tracefs_inode { + struct inode vfs_inode; + /* The below gets initialized with memset_after(ti, 0, vfs_inode) */ union { - struct inode vfs_inode; + struct list_head list; struct rcu_head rcu; }; - /* The below gets initialized with memset_after(ti, 0, vfs_inode) */ - struct list_head list; unsigned long flags; void *private; };
Your current variant gives you an RCU-delayed call of tracefs_free_inode(), which schedules an RCU-delayed call of tracefs_free_inode_rcu(). Do you really need that double RCU delay to start with? Because if you do not, just do that list_del_rcu() in ->destroy_inode() (which is called without an RCU delay) and have kmem_cache_free() in ->free_inode() (which is called *with* RCU delay started after the call of ->destroy_inode()).