From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [PATCH 04/13] block: Add bio_clone_kmalloc() Date: Fri, 18 May 2012 13:39:32 -0700 Message-ID: <20120518203932.GD9673@google.com> References: <1c7c2d4b89bc3d0e907608cec37bcf0ee50f4c0e.1337308722.git.koverstreet@google.com> <20120518160903.GD19388@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, neilb-l3A5Bk7waGM@public.gmane.org, yehuda-L5o5AL9CYN0tUFlbccrkMA@public.gmane.org, sage-BnTBU8nroG7k1uMJSBkQmQ@public.gmane.org To: Tejun Heo Return-path: Content-Disposition: inline In-Reply-To: <20120518160903.GD19388-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.vger.kernel.org On Fri, May 18, 2012 at 09:09:03AM -0700, Tejun Heo wrote: > On Thu, May 17, 2012 at 10:59:51PM -0400, koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org wrote: > > @@ -729,7 +729,7 @@ static struct bio *bio_chain_clone(struct bio **old, struct bio **next, > > } > > > > while (old_chain && (total < len)) { > > - tmp = bio_kmalloc(gfpmask, old_chain->bi_max_vecs); > > + tmp = bio_clone_kmalloc(old_chain, gfpmask); > > if (!tmp) > > goto err_out; > > > > @@ -751,13 +751,9 @@ static struct bio *bio_chain_clone(struct bio **old, struct bio **next, > > if (!bp) > > goto err_out; > > > > - __bio_clone(tmp, &bp->bio1); > > - > > This effectively swaps the order of bio_split() and __bio_clone(). Is > that safe? Also, please cc the maintainer. Now that I look at that code some more, I'm not sure it was quite right before - that or I don't follow how it's supposed to work. That bio_split() effectively does its own clone, so it seems to me the bio_kmalloc()/bio_clone_kmalloc() should only be happening in the non split case. Also, there's a bio_chain_clone in drivers/block/osdblk.c that looks like it's doing something similar, probably we should have some generic code for this.