Miklos, This is the second part of the proposal to support fanotify reporing file ids on overlayfs. The first part [1] relaxes the requirements for filesystems to support reporting events with fid to require only the ->encode_fh() operation. In this patch set, overlayfs is changed to meet the new requirements with default overlay configurations (i.e. no need for nfs_export=on). The overlayfs and vfs/fanotify patch sets are completely independent. The are both available on my github branch [2] and there is a simple LTP test variant that tests reporting fid from overlayfs [3]. Patches 2-3 are not really needed to support reporting fanotify events with fid, because overlayfs already reports a non-zero f_fsid, it's just not a very good fsid. So before allowing to report overlayfs fids, I prefer to fix f_fsid to be more unique. I went back and forth about this change of behavior (from real fsid to per-instance fsid) - can we make this change without breaking any existing workloads? I don't know. For now, I added a mount option with a very lousy name (uuid=nogen) as an escape hatch, but I also left a const bool ovl_uuid_gen_def var that we can wire to a Kconfig/module option if that is desired. Thanks, Amir. [1] https://lore.kernel.org/linux-fsdevel/20230425130105.2606684-1-amir73il@xxxxxxxxx/ [2] https://github.com/amir73il/linux/commits/exportfs_encode_fid [3] https://github.com/amir73il/ltp/commits/exportfs_encode_fid Amir Goldstein (3): ovl: support encoding non-decodeable file handles ovl: report a per-instance f_fsid by default ovl: use persistent s_uuid with index=on Documentation/filesystems/overlayfs.rst | 10 ++-- fs/overlayfs/export.c | 26 ++++++++--- fs/overlayfs/inode.c | 2 +- fs/overlayfs/overlayfs.h | 10 ++++ fs/overlayfs/ovl_entry.h | 3 +- fs/overlayfs/super.c | 62 ++++++++++++++++++++++--- fs/overlayfs/util.c | 41 ++++++++++++++++ 7 files changed, 135 insertions(+), 19 deletions(-) -- 2.34.1
