On Thu 18 Jul 16:17 PDT 2019, Al Viro wrote: > On Thu, Jul 18, 2019 at 04:10:54PM -0700, Bjorn Andersson wrote: > > Implement a wrapper for aio_read()/write() to allow async IO on files > > not implementing the iter version of read/write, such as sysfs. This > > mimics how readv/writev uses non-iter ops in do_loop_readv_writev(). > > IDGI. How would that IO manage to be async? And what's the point > using aio in such situations in the first place? The point is that an application using aio to submit io operations on a set of files, can use the same mechanism to read/write files that happens to be implemented by driver only implementing read/write (not read_iter/write_iter) in the registered file_operations struct, such as kernfs. In this particular case I have a sysfs file that is accessing hardware and hence will block for a while and using this patch I can io_submit() a write and handle the completion of this in my normal event loop. Each individual io operation will be just as synchronous as the current iter-based mechanism - for the drivers that implement that. Regards, Bjorn
