There's not need to document vfs method invocation rules, we have
Documentation/filesystems/vfs.txt and Documentation/filesystems/Locking
for that.  Also a lot of these comments where either plain wrong or
horrible out of date.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJan Kara <jack@suse.cz>