On Tue, Jul 21, 2020 at 08:59:25AM -0700, Darrick J. Wong wrote: > In the comment that precedes iomap_dio_rw() for the iomap version, maybe let's just do that.. > ``direct_IO`` > called by the generic read/write routines to perform direct_IO - > that is IO requests which bypass the page cache and transfer > data directly between the storage and the application's address > space. This function can return -ENOTBLK to signal that it is > necessary to fallback to buffered IO. Note that > blockdev_direct_IO and variants can also return -ENOTBLK. ->direct_IO is not used for iomap and various other implementations. In fact it is a horrible hack that I've been trying to get rid of for a while.