Miklos, This patch set is a prelude to the index dir feature, which requires origin verification w.r.t. upperdir. I will follow up with the posting of index dir feature soon. This work prevents: 1. Concurrent overlay mounts with same upperdir/workdir 2. Reuse of upperdir with different lowerdir 3. Merge lower dir that doesn't match upper dir origin For backward compat with existing setups that copy layers, the checks 2-3 above depend on a new mount option (-o verify_lower). The same mount option is going to determine whether an index dir that doesn't match upper dir is blown away or fails the mount. I have another dir verification patch that decodes origin dir on failure to verify lower dir, which I am using for snapshots and is going to be needed for NFS export. Because those features are not proposed for v4.13 I left out the patch from this posting. The verify_lower mount option can be tested with my unionmount-testsuite development branch [1]. I had to fix the mount cycling test (run --ov=N) not to reuse the same workdir with new rotated upperdir, because reusing workdir with different upperdir breaks the origin verification for the persistent index dir. [1] https://github.com/amir73il/unionmount-testsuite/commits/overlayfs-devel Amir Goldstein (5): vfs: introduce inode 'inuse' lock ovl: get exclusive ownership on upper/work dirs ovl: add support for verify_lower mount option ovl: verify lower root dir by file handle ovl: document the 'verify_lower' feature Documentation/filesystems/overlayfs.txt | 48 +++++++++++++ fs/inode.c | 50 ++++++++++++++ fs/overlayfs/copy_up.c | 16 +++-- fs/overlayfs/namei.c | 95 ++++++++++++++++++++++--- fs/overlayfs/overlayfs.h | 18 +++++ fs/overlayfs/ovl_entry.h | 4 ++ fs/overlayfs/super.c | 118 +++++++++++++++++++++++++++++++- fs/overlayfs/util.c | 7 ++ include/linux/fs.h | 15 ++++ 9 files changed, 351 insertions(+), 20 deletions(-) -- 2.7.4
