Re: [PATCH 46/60] block: deal with dirtying pages for multipage bvec

On Sat, Oct 29, 2016 at 04:08:45PM +0800, Ming Lei wrote:

In bio_check_pages_dirty(), bvec->bv_page is used as flag
for marking if the page has been dirtied & released, and if
no, it will be dirtied in deferred workqueue.

With multipage bvec, we can't do that any more, so change
the logic into checking all pages in one mp bvec, and only
release all these pages if all are dirtied, otherwise dirty
them all in deferred wrokqueue.

Just defer the whole bio to the workqueue if we need to redirty any,
that avoids having all these complex iteratations.