[PATCH v3 00/10] Sort out fsnotify_nameremove() mess

[Amir Goldstein <amir73il@gmail.com>]

Jan,

For v3 I went with a straight forward approach.
Filesystems that have fsnotify_{create,mkdir} hooks also get
explicit fsnotify_{unlink,rmdir} hooks.

Hopefully, this approach is orthogonal to whatever changes Al is
planning for recursive tree remove code, because in many of the
cases, the hooks are added at the entry point for the recursive
tree remove.

After looking closer at all the filesystems that were converted to
simple_remove in v2, I decided to exempt another 3 filesystems from
the fsnotify delete hooks: hypfs,qibfs and aafs.
hypfs is pure cleanup (*). qibfs and aafs can remove dentry on user
configuration change, but they do not generate create events, so it
is less likely that users depend on the delete events.

That leaves configfs the only filesystem that gets the new delete hooks
even though it does not have create hooks.

The following d_delete() call sites have been audited and will no longer
generate fsnotify event after this series:

arch/s390/hypfs/inode.c:hypfs_remove() - cleanup (*)
.../usb/gadget/function/f_fs.c:ffs_epfiles_destroy() - no create events
.../infiniband/hw/qib/qib_fs.c:remove_device_files() - no create events
fs/ceph/dir.c:ceph_unlink() - from vfs_unlink()
fs/ceph/inode.c:ceph_fill_trace() - invalidate (**)
fs/ceph/inode.c:ceph_readdir_prepopulate() - invalidate (**)
fs/configfs/dir.c:detach_groups() - hooks added, from vfs or cleanup (*)
fs/configfs/dir.c:configfs_attach_item() - cleanup (*)
fs/configfs/dir.c:configfs_attach_group() - cleanup (*)
fs/efivarfs/file.c:efivarfs_file_write() - invalidate (**)
fs/fuse/dir.c:fuse_reverse_inval_entry() - invalidate (**)
fs/nfs/dir.c:nfs_dentry_handle_enoent() - invalidate (**)
fs/nsfs.c:__ns_get_path() - cleanup (*)
fs/ocfs2/dlmglue.c:ocfs2_dentry_convert_worker() - invalidate (**)
fs/reiserfs/xattr.c:xattr_{unlink,rmdir}() - hidden xattr inode
security/apparmor/apparmorfs.c:aafs_remove() - no create events

(*) There are 2 "cleanup" use cases:
  - Create;init;delete if init failed
  - Batch delete of files within dir before removing dir
  Both those cases are not interesting for users that wish to observe
  configuration changes on pseudo filesystems.  Often, there is already
  an fsnotify event generated on the directory removal which is what
  users should find interesting, for example:
  configfs_unregister_{group,subsystem}().

(**) The different "invalidate" use cases differ, but they all share
  one thing in common - user is not guarantied to get an event with
  current kernel.  For example, when a file is deleted remotely on
  nfs server, nfs client is not guarantied to get an fsnotify delete
  event.  On current kernel, nfs client could generate an fsnotify
  delete event if the local entry happens to be in cache and client
  finds out that entry is deleted on server during another user
  operation.  Incidentally, this group of use cases is where most of
  the call sites are with "unstable" d_name, which is the reason for
  this patch series to begin with.

Thanks,
Amir.

Changes since v2:
- Drop simple_rename() conversions (add explicit hooks instead)
- Drop hooks from hypfs/qibfs/aafs
- Split out debugfs re-factoring patch

Changes since v1:
- Split up per filesystem patches
- New hook names fsnotify_{unlink,rmdir}()
- Simplify fsnotify code in separate final patch

Amir Goldstein (10):
  fsnotify: add empty fsnotify_{unlink,rmdir}() hooks
  btrfs: call fsnotify_rmdir() hook
  rpc_pipefs: call fsnotify_{unlink,rmdir}() hooks
  tracefs: call fsnotify_{unlink,rmdir}() hooks
  devpts: call fsnotify_unlink() hook
  debugfs: simplify __debugfs_remove_file()
  debugfs: call fsnotify_{unlink,rmdir}() hooks
  configfs: call fsnotify_rmdir() hook
  fsnotify: move fsnotify_nameremove() hook out of d_delete()
  fsnotify: get rid of fsnotify_nameremove()

 fs/afs/dir_silly.c               |  5 ----
 fs/btrfs/ioctl.c                 |  4 +++-
 fs/configfs/dir.c                |  3 +++
 fs/dcache.c                      |  2 --
 fs/debugfs/inode.c               | 21 ++++++++--------
 fs/devpts/inode.c                |  1 +
 fs/namei.c                       |  2 ++
 fs/nfs/unlink.c                  |  6 -----
 fs/notify/fsnotify.c             | 41 --------------------------------
 fs/tracefs/inode.c               |  3 +++
 include/linux/fsnotify.h         | 26 ++++++++++++++++++++
 include/linux/fsnotify_backend.h |  4 ----
 net/sunrpc/rpc_pipe.c            |  4 ++++
 13 files changed, 52 insertions(+), 70 deletions(-)

-- 
2.17.1