On Thu, Aug 17, 2017 at 06:08:15PM +0200, Jan Kara wrote: > We return IOMAP_F_NEEDDSYNC flag from ext4_iomap_begin() for a > synchronous write fault when inode has some uncommitted metadata > changes. In the fault handler ext4_dax_fault() we then detect this case, > call vfs_fsync_range() to make sure all metadata is committed, and call > dax_pfn_mkwrite() to mark PTE as writeable. Note that this will also > dirty corresponding radix tree entry which is what we want - fsync(2) > will still provide data integrity guarantees for applications not using > userspace flushing. And applications using userspace flushing can avoid > calling fsync(2) and thus avoid the performance overhead. Why is this only wiered up for the huge_fault handler and not the regular?
