On Thu, Jul 27, 2017 at 03:12:40PM +0200, Jan Kara wrote: > Add 'sync' argument to dax_iomap_fault(). It will be used to communicate > the fact that synchronous fault is requested. I don't actually think you need to pass this 'sync' parameter around. I think you can completely rely on IOMAP_F_NEEDSYNC being set in iomap.flags. The DAX fault handlers can call ops->iomap_begin() and use that flag for all the tests and make it our once source of truth. That flag also tells us that we are doing a write fault (from ext4_iomap_begin()): if ((flags & IOMAP_FAULT) && (flags & IOMAP_WRITE) && IS_SYNC(inode) && !jbd2_transaction_committed(EXT4_SB(inode->i_sb)->s_journal, EXT4_I(inode)->i_datasync_tid)) iomap->flags |= IOMAP_F_NEEDDSYNC; So conditionals like this from dax_iomap_pte_fault(): force_ro = (vmf->flags & FAULT_FLAG_WRITE) && sync && (iomap.flags & IOMAP_F_NEEDDSYNC); can be simplified to: force_ro = (iomap.flags & IOMAP_F_NEEDDSYNC);
