Extend fanotify dirent events

Jan,

This is the 2nd version of FAN_REPORT_TARGET_FID patches [1].

In the first version, extra info records about new and old parent+name
were added to FAN_MOVED_FROM event.  This version uses a new event
FAN_RENAME instead, to report those extra info records.
The new FAN_RENAME event was designed as a replacement for the
"inotify way" of joining the MOVED_FROM/MOVED_TO events using a cookie.

FAN_RENAME event differs from MOVED_FROM/MOVED_TO events in several ways:
1) The information about old/new names is provided in a single event
2) When added to the ignored mask of a directory, FAN_RENAME is not
   reported for renames to and from that directory

The group flag FAN_REPORT_TARGET_FID adds an extra info record of
the child fid to all the dirent events, including FAN_REANME.
It is independent of the FAN_RENAME changes and implemented in the
first patch, so it can be picked regardless of the FAN_RENAME patches.

Patches [2] and LTP test [3] are available on my github.
A man page draft will be provided later on.

Thanks,
Amir.

[1] https://lore.kernel.org/linux-fsdevel/20211029114028.5697...
[2] https://github.com/amir73il/linux/commits/fan_rename
[3] https://github.com/amir73il/ltp/commits/fan_rename

Amir Goldstein (9):
  fanotify: introduce group flag FAN_REPORT_TARGET_FID
  fsnotify: generate FS_RENAME event with rich information
  fanotify: use macros to get the offset to fanotify_info buffer
  fanotify: use helpers to parcel fanotify_info buffer
  fanotify: support secondary dir fh and name in fanotify_info
  fanotify: record old and new parent and name in FAN_RENAME event
  fanotify: record either old name new name or both for FAN_RENAME
  fanotify: report old and/or new parent+name in FAN_RENAME event
  fanotify: wire up FAN_RENAME event

 fs/notify/dnotify/dnotify.c        |   2 +-
 fs/notify/fanotify/fanotify.c      | 209 +++++++++++++++++++++++------
 fs/notify/fanotify/fanotify.h      | 142 ++++++++++++++++++--
 fs/notify/fanotify/fanotify_user.c |  75 +++++++++--
 fs/notify/fsnotify.c               |  14 ++
 include/linux/dnotify.h            |   2 +-
 include/linux/fanotify.h           |   5 +-
 include/linux/fsnotify.h           |   9 +-
 include/linux/fsnotify_backend.h   |   6 +-
 include/uapi/linux/fanotify.h      |  12 ++
 10 files changed, 405 insertions(+), 71 deletions(-)

-- 
2.33.1