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Message-ID: <20190411231443.GD1695@dread.disaster.area> Date: Fri, 12 Apr 2019 09:14:43 +1000 From: Dave Chinner <david@...morbit.com> To: jglisse@...hat.com Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org, linux-mm@...ck.org, John Hubbard <jhubbard@...dia.com>, Jan Kara <jack@...e.cz>, Dan Williams <dan.j.williams@...el.com>, Alexander Viro <viro@...iv.linux.org.uk>, Johannes Thumshirn <jthumshirn@...e.de>, Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>, Ming Lei <ming.lei@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>, Matthew Wilcox <willy@...radead.org>, Ernesto A . Fernández <ernesto.mnd.fernandez@...il.com>, Jeff Moyer <jmoyer@...hat.com> Subject: Re: [PATCH v1 12/15] fs/direct-io: keep track of wether a page is coming from GUP or not On Thu, Apr 11, 2019 at 05:08:31PM -0400, jglisse@...hat.com wrote: > From: Jérôme Glisse <jglisse@...hat.com> > > We want to keep track of how we got a reference on page when doing DIO, > ie wether the page was reference through GUP (get_user_page*) or not. > For that this patch rework the way page reference is taken and handed > over between DIO code and BIO. Instead of taking a reference for page > that have been successfuly added to a BIO we just steal the reference > we have when we lookup the page (either through GUP or for ZERO_PAGE). > > So this patch keep track of wether the reference has been stolen by the > BIO or not. This avoids a bunch of get_page()/put_page() so this limit > the number of atomic operations. Is the asme set of changes appropriate for the fs/iomap.c direct IO path (i.e. XFS)? -Dave. -- Dave Chinner david@...morbit.com
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