From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH v2 15/26] block: Add bio_copy_data() Date: Thu, 20 Sep 2012 17:15:01 -0700 Message-ID: <20120921001501.GU7264@google.com> References: <1347322957-25260-1-git-send-email-koverstreet@google.com> <1347322957-25260-16-git-send-email-koverstreet@google.com> <20120921000632.GS7264@google.com> <20120921000945.GK5519@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120921000945.GK5519-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kent Overstreet Cc: 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, neilb-l3A5Bk7waGM@public.gmane.org List-Id: linux-bcache@vger.kernel.org On Thu, Sep 20, 2012 at 05:09:45PM -0700, Kent Overstreet wrote: > On Thu, Sep 20, 2012 at 05:06:32PM -0700, Tejun Heo wrote: > > Hello, > > > > On Mon, Sep 10, 2012 at 05:22:26PM -0700, Kent Overstreet wrote: > > > +void bio_copy_data(struct bio *dst, struct bio *src) > > > +{ > > ... > > > + src_p = kmap_atomic(src_bv->bv_page); > > > + dst_p = kmap_atomic(dst_bv->bv_page); > > > + > > > + memcpy(dst_p + dst_bv->bv_offset, > > > + src_p + src_bv->bv_offset, > > > + bytes); > > > + > > > + kunmap_atomic(dst_p); > > > + kunmap_atomic(src_p); > > > > Wrap these in preempt_disable/enable() to allow the function to be > > called from any context? > > I checked the implementation of kmap_atomic(), it already does > preempt_disable() so it's safe in process context - if I understand > correctly it needs local_irq_save()/restore() to be safe in any context > and I figured calling this from irq context is not the norm so that > should be the caller's responsibility. Ooh, that means the patch I just sent Andrew about sg_mapping_iter is still too strict. Thanks. -- tejun