On Thu, Apr 13, 2023 at 09:40:29AM +0200, Miklos Szeredi wrote: > fuse_direct_write_iter(): > > bool exclusive_lock = > !(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES) || > iocb->ki_flags & IOCB_APPEND || > fuse_direct_write_extending_i_size(iocb, from); > > If the write is size extending, then it will take the lock exclusive. > OTOH, I guess that it would be unusual for lots of size extending > writes to be done in parallel. > > What would be the effect of giving the FMODE_DIO_PARALLEL_WRITE hint > and then still serializing the writes? I have no idea how this flags work, but XFS also takes i_rwsem exclusively for appends, when the positions and size aren't aligned to the block size, and a few other cases.
