From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [Drbd-dev] [PATCH v3 06/26] block: Add bio_end_sector() Date: Tue, 25 Sep 2012 15:06:24 -0700 Message-ID: <20120925220624.GC22647@google.com> References: <1348526106-17074-1-git-send-email-koverstreet@google.com> <1348526106-17074-7-git-send-email-koverstreet@google.com> <20120925115452.GF8143@soda.linbit> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120925115452.GF8143-w1SgEEioFePxa46PmUWvFg@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Chris Mason , neilb-l3A5Bk7waGM@public.gmane.org, Jiri Kosina , Heiko Carstens , Martin Schwidefsky , Alasdair Kergon , tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Steven Whitehouse , vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Lars Ellenberg List-Id: linux-bcache@vger.kernel.org On Tue, Sep 25, 2012 at 01:54:52PM +0200, Lars Ellenberg wrote: > On Mon, Sep 24, 2012 at 03:34:46PM -0700, Kent Overstreet wrote: > > Just a little convenience macro - main reason to add it now is preparing > > for immutable bio vecs, it'll reduce the size of the patch that puts > > bi_sector/bi_size/bi_idx into a struct bvec_iter. > > > For the DRBD part: > > > diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c > > index 01b2ac6..d90a1fd 100644 > > --- a/drivers/block/drbd/drbd_req.c > > +++ b/drivers/block/drbd/drbd_req.c > > @@ -1144,7 +1144,7 @@ void drbd_make_request(struct request_queue *q, struct bio *bio) > > /* to make some things easier, force alignment of requests within the > > * granularity of our hash tables */ > > s_enr = bio->bi_sector >> HT_SHIFT; > > - e_enr = bio->bi_size ? (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT : s_enr; > > + e_enr = (bio_end_sector(bio) - 1) >> HT_SHIFT; > > You ignored the bio->bi_size ? : ; > > #define bio_end_sector(bio) ((bio)->bi_sector + bio_sectors(bio)) > which turns out (bio->bi_sector + (bio->bi_size >> 9)) > > Note that bi_size may be 0, bio_end_sector(bio)-1 then is bi_sector -1, > for an empty flush with bi_sector == 0, this ends up as (sector_t)-1ULL, > and this code path breaks horribly. Man, that was dumb of me - thanks for catching it. Version below look good? diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 01b2ac6..47f55db 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -1144,7 +1144,7 @@ void drbd_make_request(struct request_queue *q, struct bio *bio) /* to make some things easier, force alignment of requests within the * granularity of our hash tables */ s_enr = bio->bi_sector >> HT_SHIFT; - e_enr = bio->bi_size ? (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT : s_enr; + e_enr = bio->bi_size ? (bio_end_sector(bio) - 1) >> HT_SHIFT : s_enr; if (likely(s_enr == e_enr)) { do {