I've done some work to fix and enhance shiftfs for a number of use cases, so that we would have an idea what a more full-featured shiftfs would look like. I'm intending for these to serve as a point of reference for discussing id shifting mounts/filesystems at plumbers in a couple of weeks [1]. Note that these are based on 4.18, and I've added a small fix to James' most recent patch to fix a build issue there. To work with 4.19 they will need a number of updates due to changes in the vfs. The features I focused on fixing in or adding to shiftfs in these patches are inotify, file capabilities, posix acls, and nesting. These are all now working for at least simple use cases, but further testing and cleanups are needed before I'd consider these finished. I also kept all the changes within shiftfs, but some of the code might belong in the vfs instead (in particular some of the posix acl code). I've also pushed these patches to: git://git.kernel.org/pub/scm/linux/kernel/git/sforshee/linux.git shiftfs Thanks, Seth [1] https://linuxplumbersconf.org/event/2/contributions/212/ --- James Bottomley (1): shiftfs: uid/gid shifting bind mount Seth Forshee (5): shiftfs: map inodes to lower fs inodes instead of dentries shiftfs: copy inode attrs up from underlying fs shiftfs: translate uids using s_user_ns from lower fs shiftfs: add support for posix acls shiftfs: support nested shiftfs mounts fs/Kconfig | 18 + fs/Makefile | 1 + fs/shiftfs.c | 1075 ++++++++++++++++++++++++++++++++++++ include/uapi/linux/magic.h | 2 + 4 files changed, 1096 insertions(+) create mode 100644 fs/shiftfs.c
