From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 13 Jun 2018 15:56:32 +0200 From: Christoph Hellwig To: Ming Lei Cc: Kent Overstreet , Christoph Hellwig , Jens Axboe , Coly Li , linux-bcache@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [RFC] cleanup bcache bio handling Message-ID: <20180613135632.GB32418@lst.de> References: <20180611194806.13222-1-hch@lst.de> <20180613095801.GB15100@kmo-pixel> <20180613110640.GA9712@ming.t460p> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: <20180613110640.GA9712@ming.t460p> List-ID: On Wed, Jun 13, 2018 at 07:06:41PM +0800, Ming Lei wrote: > > before bio_alloc_pages) that can be switched to something that just creates a > > single bvec. > > Yes, multipage bvec shouldn't break any driver or fs. It probably isn't broken, at least I didn't see assumptions of the same number of segments. However the current poking into the bio internals as a bad idea for a couple of reasons. First because it requires touching bcache for any of these changes, second because it won't get merging of pages into a single bio segment for bіos built by bch_bio_map or bch_bio_alloc_pages, and third bcache is the last user of bio_for_each_chunk_all in your branch, which I'd like to kill off to keep the number of iterators down.