commit 702eb71fd6501b3566283f8c96d7ccc6ddd662e9 upstream.

Currently we will not generate FS_OPEN events for O_PATH file
descriptors but we will generate FS_CLOSE events for them. This is
asymmetry is confusing. Arguably no fsnotify events should be generated
for O_PATH file descriptors as they cannot be used to access or modify
file content, they are just convenient handles to file objects like
paths. So fix the asymmetry by stopping to generate FS_CLOSE for O_PATH
file descriptors.

Cc: <stable@vger.kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240617162303.1596-1-jack@suse.cz
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit a37d9a17f099072fe4d3a9048b0321978707a918 upstream.

Apparently, there are some applications that use IN_DELETE event as an
invalidation mechanism and expect that if they try to open a file with
the name reported with the delete event, that it should not contain the
content of the deleted file.

Commit 49246466a989 ("fsnotify: move fsnotify_nameremove() hook out of
d_delete()") moved the fsnotify delete hook before d_delete() so fsnotify
will have access to a positive dentry.

This allowed a race where opening the deleted file via cached dentry
is now possible after receiving the IN_DELETE event.

To fix the regression, create a new hook fsnotify_delete() that takes
the unlinked inode as an argument and use a helper d_delete_notify() to
pin the inode, so we can pass it to fsnotify_delete() after d_delete().

Backporting hint: this regression is from v5.3. Although patch will
apply with only trivial conflicts to v5.4 and v5.10, it won't build,
because fsnotify_delete() implementation is different in each of those
versions (see fsnotify_link()).

A follow up patch will fix the fsnotify_unlink/rmdir() calls in pseudo
filesystem that do not need to call d_delete().

Link: https://lore.kernel.org/r/20220120215305.282577-1-amir73il@gmail.com
Reported-by: Ivan Delalande <colona@arista.com>
Link: https://lore.kernel.org/linux-fsdevel/YeNyzoDM5hP5LtGW@visor/
Fixes: 49246466a989 ("fsnotify: move fsnotify_nameremove() hook out of d_delete()")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

For all callers of fsnotify_{unlink,rmdir}(), we made sure that d_parent
and d_name are stable.  Therefore, fsnotify_{unlink,rmdir}() do not need
the safety measures in fsnotify_nameremove() to stabilize parent and name.
We can now simplify those hooks and get rid of fsnotify_nameremove().

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

d_delete() was piggy backed for the fsnotify_nameremove() hook when
in fact not all callers of d_delete() care about fsnotify events.

For all callers of d_delete() that may be interested in fsnotify events,
we made sure to call one of fsnotify_{unlink,rmdir}() hooks before
calling d_delete().

Now we can move the fsnotify_nameremove() call from d_delete() to the
fsnotify_{unlink,rmdir}() hooks.

Two explicit calls to fsnotify_nameremove() from nfs/afs sillyrename
are also removed. This will cause a change of behavior - nfs/afs will
NOT generate an fsnotify delete event when renaming over a positive
dentry.  This change is desirable, because it is consistent with the
behavior of all other filesystems.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

We would like to move fsnotify_nameremove() calls from d_delete()
into a higher layer where the hook makes more sense and so we can
consider every d_delete() call site individually.

Start by creating empty hook fsnotify_{unlink,rmdir}() and place
them in the proper VFS call sites.  After all d_delete() call sites
will be converted to use the new hook, the new hook will generate the
delete events and fsnotify_nameremove() hook will be removed.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Pull fsnotify fixes from Jan Kara:
 "Two fsnotify fixes"

* tag 'fsnotify_for_v5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: fix unlink performance regression
  fsnotify: Clarify connector assignment in fsnotify_add_mark_list()

__fsnotify_parent() has an optimization in place to avoid unneeded
take_dentry_name_snapshot().  When fsnotify_nameremove() was changed
not to call __fsnotify_parent(), we left out the optimization.
Kernel test robot reported a 5% performance regression in concurrent
unlink() workload.

Reported-by: kernel test robot <rong.a.chen@intel.com>
Link: https://lore.kernel.org/lkml/20190505062153.GG29809@shao2-debian/
Link: https://lore.kernel.org/linux-fsdevel/20190104090357.GD22409@quack2.suse.cz/
Fixes: 5f02a8776384 ("fsnotify: annotate directory entry modification events")
CC: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Note that in fnsotify_move() and fsnotify_link() we are guaranteed
that dentry->d_name won't change during the fsnotify() evaluation
(by having the parent directory locked exclusive), so we don't
need to fetch dentry->d_name.name in the callers.  In fsnotify_dirent()
the same stability of dentry->d_name is also true, but it's a bit
more convoluted - there is one callchain (devpts_pty_new() ->
fsnotify_create() -> fsnotify_dirent()) where the parent is _not_
locked, but on devpts ->d_name of everything is unchanging; it
has neither explicit nor implicit renames.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

note that in the second (RENAME_EXCHANGE) call of fsnotify_move() in
vfs_rename() the old_dentry->d_name is guaranteed to be unchanged
throughout the evaluation of fsnotify_move() (by the fact that the
parent directory is locked exclusive), so we don't need to fetch
old_dentry->d_name.name in the caller.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>