Hello, Greg: If this looks good to you, can you apply 0001-0008 to your tree? I'll likely have more cgroup updates on top, so I think it'd be better if I pull your tree and then handle the cgroup part in cgroup tree. 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 implements kernfs_show() which can dynamically show and hide kernfs_nodes using the [de]activation mechanisms, and, on top, implements 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 nine 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-Improve-kernfs_drain-and-always-call-on-remov.patch 0006-kernfs-Add-KERNFS_REMOVING-flags.patch 0007-kernfs-Factor-out-kernfs_activate_one.patch 0008-kernfs-Implement-kernfs_show.patch 0009-cgroup-Implement-cgroup_file_show.patch 0001-0003 are misc prep patches. 0004-0008 implement kernsf_deactivate(). 0009 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-show The main difference from the previous version[1] is that while show/hide still use the same mechanism as [de]activation, their states are tracked separately so that e.g. an unrelated kernfs_activate() higher up in the tree doesn't interfere with hidden nodes in the subtree. diffstat follows. Thanks. fs/kernfs/dir.c | 102 +++++++++++++++++++++++++++++++---------------- fs/kernfs/file.c | 151 +++++++++++++++++++++++++++++++++------------------------------------- fs/kernfs/kernfs-internal.h | 1 include/linux/cgroup.h | 1 include/linux/kernfs.h | 3 + kernel/cgroup/cgroup.c | 20 +++++++++ 6 files changed, 166 insertions(+), 112 deletions(-) -- tejun [1] http://lkml.kernel.org/r/20220820000550.367085-1-tj@xxxxxxxxxx
