Hello, Currently, deactivated kernfs nodes are used for two purposes - during removal to kill and drain nodes and during creation to make multiple kernfs_nodes creations to succeed or fail as a group. This patchset make kernfs [de]activation generic so that it can be used anytime to deactivate (hide and drain) and activate (show) kernfs nodes, and, on top, implement cgroup_file_show() which allows toggling cgroup file visiblity. This is for the following pending patchset to allow disabling PSI on per-cgroup basis: https://lore.kernel.org/all/20220808110341.15799-1-zhouchengming@xxxxxxxxxxxxx/t/#u which requires hiding the corresponding cgroup interface files while disabled. This patchset contains the following seven patches. 0001-kernfs-Simply-by-replacing-kernfs_deref_open_node-wi.patch 0002-kernfs-Drop-unnecessary-mutex-local-variable-initial.patch 0003-kernfs-Refactor-kernfs_get_open_node.patch 0004-kernfs-Skip-kernfs_drain_open_files-more-aggressivel.patch 0005-kernfs-Make-kernfs_drain-skip-draining-more-aggressi.patch 0006-kernfs-Allow-kernfs-nodes-to-be-deactivated-and-re-a.patch 0007-cgroup-Implement-cgroup_file_show.patch 0001-0003 are misc prep patches. 0004-0006 implement kernsf_deactivate(). 0008 implements cgroup_file_show() on top. The patches are also available in the following git branch: git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git kernfs-deactivate diffstat follows. Thanks. fs/kernfs/dir.c | 120 +++++++++++++++++++++++++++++++++++++++++------------------- fs/kernfs/file.c | 139 +++++++++++++++++++++++++++++++--------------------------------------- fs/kernfs/kernfs-internal.h | 1 include/linux/cgroup.h | 1 include/linux/kernfs.h | 2 + kernel/cgroup/cgroup.c | 23 +++++++++++ 6 files changed, 172 insertions(+), 114 deletions(-) -- tejun
