From c51db71fc143a5e0014219deda9cad05c4352e7f Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 11 Jun 2025 12:18:15 -0400 Subject: [PATCH] tracefs: Add d_delete to remove negative dentries [ Upstream commit d9b13cdad80dc11d74408cf201939a946e9303a6 ] If a lookup in tracefs is done on a file that does not exist, it leaves a dentry hanging around until memory pressure removes it. But eventfs dentries should hang around as when their ref count goes to zero, it requires more work to recreate it. For the rest of the tracefs dentries, they hang around as their dentry is used as a descriptor for the tracing system. But if a file lookup happens for a file in tracefs that does not exist, it should be deleted. Add a .d_delete callback that checks if dentry->fsdata is set or not. Only eventfs dentries set fsdata so if it has content it should not be deleted and should hang around in the cache. Reported-by: Al Viro Signed-off-by: Steven Rostedt (Google) Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/tracefs/inode.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index cfc614c638daf..9f15d606dfde7 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -464,9 +464,20 @@ static int tracefs_d_revalidate(struct dentry *dentry, unsigned int flags) return !(ei && ei->is_freed); } +static int tracefs_d_delete(const struct dentry *dentry) +{ + /* + * We want to keep eventfs dentries around but not tracefs + * ones. eventfs dentries have content in d_fsdata. + * Use d_fsdata to determine if it's a eventfs dentry or not. + */ + return dentry->d_fsdata == NULL; +} + static const struct dentry_operations tracefs_dentry_operations = { .d_revalidate = tracefs_d_revalidate, .d_release = tracefs_d_release, + .d_delete = tracefs_d_delete, }; static int tracefs_fill_super(struct super_block *sb, struct fs_context *fc) -- 2.47.3