Re: [PATCH 3/8] nowait aio: return if direct write will trigger writeback

On 03/16/2017 08:20 AM, Matthew Wilcox wrote:

On Wed, Mar 15, 2017 at 04:51:02PM -0500, Goldwyn Rodrigues wrote:

quoted

From: Goldwyn Rodrigues <rgoldwyn-IBi9RG/b67k@public.gmane.org>

Find out if the write will trigger a wait due to writeback. If yes,
return -EAGAIN.

This introduces a new function filemap_range_has_page() which
returns true if the file's mapping has a page within the range
mentioned.

Return -EINVAL for buffered AIO: there are multiple causes of
delay such as page locks, dirty throttling logic, page loading
from disk etc. which cannot be taken care of.

Also, this patch only touches the write path; we have a similar call to
write_and_wait_range() in generic_file_read_iter().

This patch series is concerned with direct-write AIO paths only.

-- 
Goldwyn