On Thu, Oct 17, 2024 at 01:36:41PM -0400, Waiman Long wrote: > > At least for the XFS use case where direct I/O takes a share lock > > that needs to be replaced with an exclusive one for certain kinds of > > I/O would be useless. But then again we've survived without this > > operation for a long time, despite the initial port bringing one over > > from IRIX. > > That means XFS only needs to upgrade to a write lock in certain cases only, > not all of them. Yes. Basically when we detect a direct I/O writes needs to clear the SUID bit or other metadata, or when it is an extending write. > Right? In that case, read_try_upgrade() that attempts to > upgrade to a write lock will be useful. Yes. But I also understand Peters reasoning that it will be very hard to actually have a useful implementation that does better than just unlocking (which is what we do currently).
