fanotify: factor out helper fanotify_mark_update_flags()

[ Upstream commit 8998d110 ]

Handle FAN_MARK_IGNORED_SURV_MODIFY flag change in a helper that
is called after updating the mark mask.

Replace the added and removed return values and help variables with
bool recalc return values and help variable, which makes the code a
bit easier to follow.

Rename flags argument to fan_flags to emphasize the difference from
mark->flags.

Link: https://lore.kernel.org/r/20220422120327.3459282-14-amir73il@gmail.com


Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>