[PATCH REPOST v2 0/2] Support fanotify FAN_REPORT_FID on all filesystems

From: Amir Goldstein <amir73il@gmail.com>
To: Jan Kara <jack@suse.cz>
Cc: Christian Brauner <brauner@kernel.org>, linux-fsdevel@vger.kernel.org
Subject: [PATCH REPOST v2 0/2] Support fanotify FAN_REPORT_FID on all filesystems
Date: Thu, 30 Nov 2023 19:17:05 +0200	[thread overview]
Message-ID: <20231130171707.3387792-1-amir73il@gmail.com> (raw)

Jan,

In the vfs fanotify update for v6.7-rc1 [1], we considerably increased
the amount of filesystems that can setup inode marks with FAN_REPORT_FID:
- NFS export is no longer required for setting up inode marks
- All the simple fs gained a non-zero fsid

This leaves the following in-tree filesystems where inode marks with
FAN_REPORT_FID cannot be set:
- nfs, fuse, afs, coda (zero fsid)
- btrfs non-root subvol (fsid not a unique identifier of sb)

This patch set takes care of these remaining cases, by allowing inode
marks, as long as all inode marks in the group are contained to the same
filesystem and same fsid (i.e. subvol).

I've written some basic sanity tests [2] and a man-page update draft [3].
The LTP tests excersize the new code by running tests that did not run
before on ntfs-3g fuse filesystem and skipping the test cases with mount
and sb marks.

I've also tested fsnotifywait --recursive on fuse and on btrfs subvol.
It works as expected - if tree travesal crosses filesystem or subvol
boundary, setting the subdir mark fails with -EXDEV.

Thanks,
Amir.

[1] https://lore.kernel.org/linux-fsdevel/20231107-vfs-fsid-5037e344d215@brauner/
[2] https://github.com/amir73il/ltp/commits/fanotify_fsid
[3] https://github.com/amir73il/man-pages/commits/fanotify_fsid

Changes since v1:
- Add missing fsnotify_put_mark()
- Improve readablity of fanotify_test_fsid()
- Rename fanotify_check_mark_fsid() => fanotify_set_mark_fsid()
- Remove fanotify_mark_fsid() wrapper

Amir Goldstein (2):
  fanotify: store fsid in mark instead of in connector
  fanotify: allow "weak" fsid when watching a single filesystem

 fs/notify/fanotify/fanotify.c      |  34 ++------
 fs/notify/fanotify/fanotify.h      |  16 ++++
 fs/notify/fanotify/fanotify_user.c | 124 ++++++++++++++++++++++++-----
 fs/notify/mark.c                   |  52 ++----------
 include/linux/fsnotify_backend.h   |  14 ++--
 5 files changed, 140 insertions(+), 100 deletions(-)

-- 
2.34.1