fanotify support for btrfs sub-volumes

Jan,

As agreed on the review of v1 [1], we do not need any vfs changes
to support fanotify on btrfs sub-volumes and we can enable setting
marks on btrfs sub-volumes simply by caching the fsid in the mark
object instead of the connector.

This is the would be man page update to clarify the meaning of fsid
as it is reflected in this patch set:

fsid

  This is a unique identifier of the filesystem containing the object
  associated with the event.  It is a structure of type __kernel_fsid_t
  and contains the same value reported in  f_fsid  when calling
  statfs(2) with the same pathname argument that was used for
  fanotify_mark(2).  Note that some filesystems (e.g., btrfs(5)) report
  non-uniform values of f_fsid on different objects of the same filesystem.
  In these cases, if fanotify_mark(2) is called several times with different
  pathname values, the fsid value reported in events will match f_fsid
  associated  with at least one of those pathname values.

Thanks,
Amir.

[1] https://lore.kernel.org/r/CAOQ4uxg9wjESoCFNDADbneF0-nW4xV...

Amir Goldstein (3):
  fanotify: store fsid in mark instead of in connector
  fanotify: report the most specific fsid for btrfs
  fanotify: support setting marks in btrfs sub-volumes

 fs/notify/fanotify/fanotify.c      | 21 ++++--------
 fs/notify/fanotify/fanotify.h      | 10 ++++++
 fs/notify/fanotify/fanotify_user.c | 31 ++++++++----------
 fs/notify/mark.c                   | 52 +++++-------------------------
 include/linux/fsnotify_backend.h   | 18 +++++------
 5 files changed, 47 insertions(+), 85 deletions(-)

-- 
2.34.1