On 03/16/2017 08:08 AM, Matthew Wilcox wrote: > On Wed, Mar 15, 2017 at 04:51:02PM -0500, Goldwyn Rodrigues wrote: >> This introduces a new function filemap_range_has_page() which >> returns true if the file's mapping has a page within the range >> mentioned. > > I thought you were going to replace this patch with one that starts > writeback for these pages but does not wait for them? > As mentioned by Jan, Flags to filemap_write_and_wait_range are unnecessarily complicated. The AIO-DIO API users who eye for performance usually are careful with page writes/evictions. As a fallback, they can (and should) go the wait route (without IOCB_RW_FLAG_NOWAIT). Finally, my take on this is that we don't want to perform tasks for a following system call, which may or may not immediately follow the current one. May not, because an application (DB) will offload the task from the CPU thread to the I/O thread in case of -EAGAIN. A system call should be complete in itself (and do the minimum, what is asked). -- Goldwyn
