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Date: Wed, 28 May 2014 23:42:55 +0800 From: Ming Lei <tom.leiming@...il.com> To: Dongsu Park <dongsu.park@...fitbricks.com> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Jens Axboe <axboe@...nel.dk>, Jet Chen <jet.chen@...el.com>, Maurizio Lombardi <mlombard@...hat.com> Subject: Re: [PATCH] bio: decrease bi_iter.bi_size by len in the fail path Hi Dongsu, On Wed, May 28, 2014 at 11:09 PM, Dongsu Park <dongsu.park@...fitbricks.com> wrote: > From: Dongsu Park <dongsu.park@...fitbricks.com> > > Commit 3979ef4dcf3d1de55a560a3a4016c30a835df44d ("bio-modify- > __bio_add_page-to-accept-pages-that-dont-start-a-new-segment-v3") > introduced a regression as reported by Jet Chen. > That results in a kernel BUG at drivers/block/virtio_blk.c:166. > > To fix that, bi_iter.bi_size must be decreased by len, before > recounting the number of physical segments. > > Tested on with kernel 3.15.0-rc7-next-20140527 on qemu guest, > by running xfstests/ext4/271. > > Cc: Jens Axboe <axboe@...nel.dk> > Cc: Jet Chen <jet.chen@...el.com> > Cc: Maurizio Lombardi <mlombard@...hat.com> > Signed-off-by: Dongsu Park <dongsu.park@...fitbricks.com> > --- > block/bio.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/block/bio.c b/block/bio.c > index 0443694ccbb4..67d7cba1e5fd 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -810,6 +810,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page > bvec->bv_len = 0; > bvec->bv_offset = 0; > bio->bi_vcnt--; > + bio->bi_iter.bi_size -= len; Would you mind explaining why bi_iter.bi_size need to be decreased by 'len'? In the failure path, it wasn't added by 'len', was it? Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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