From 783bd07d095b722108725af11113795ee046ed0e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 27 Aug 2022 19:04:39 -1000 Subject: kernfs: Implement kernfs_show() Currently, kernfs nodes can be created hidden and activated later by calling kernfs_activate() to allow creation of multiple nodes to succeed or fail as a unit. This is an one-way one-time-only transition. This patch introduces kernfs_show() which can toggle visibility dynamically. As the currently proposed use - toggling the cgroup pressure files - only requires operating on leaf nodes, for the sake of simplicity, restrict it as such for now. Hiding uses the same mechanism as deactivation and likewise guarantees that there are no in-flight operations on completion. KERNFS_ACTIVATED and KERNFS_HIDDEN are used to manage the interactions between activations and show/hide operations. A node is visible iff both activated & !hidden. Cc: Chengming Zhou Cc: Johannes Weiner Tested-by: Chengming Zhou Reviewed-by: Chengming Zhou Signed-off-by: Tejun Heo Link: https://lore.kernel.org/r/20220828050440.734579-9-tj@kernel.org Signed-off-by: Greg Kroah-Hartman --- include/linux/kernfs.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index b77d257c1f7e..73f5c120def8 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -108,6 +108,7 @@ enum kernfs_node_flag { KERNFS_HAS_SEQ_SHOW = 0x0040, KERNFS_HAS_MMAP = 0x0080, KERNFS_LOCKDEP = 0x0100, + KERNFS_HIDDEN = 0x0200, KERNFS_SUICIDAL = 0x0400, KERNFS_SUICIDED = 0x0800, KERNFS_EMPTY_DIR = 0x1000, @@ -430,6 +431,7 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, const char *name, struct kernfs_node *target); void kernfs_activate(struct kernfs_node *kn); +void kernfs_show(struct kernfs_node *kn, bool show); void kernfs_remove(struct kernfs_node *kn); void kernfs_break_active_protection(struct kernfs_node *kn); void kernfs_unbreak_active_protection(struct kernfs_node *kn); -- cgit v1.2.3-59-g8ed1b