From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Durgin Subject: Re: [PATCH 3/4] rbd: define zero_pages() Date: Mon, 22 Apr 2013 01:05:28 -0700 Message-ID: <5174EF48.3020308@inktank.com> References: <5171C963.2050402@inktank.com> <5171CA29.7000500@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-da0-f41.google.com ([209.85.210.41]:34859 "EHLO mail-da0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754365Ab3DVIFc (ORCPT ); Mon, 22 Apr 2013 04:05:32 -0400 Received: by mail-da0-f41.google.com with SMTP id p8so2860840dan.14 for ; Mon, 22 Apr 2013 01:05:31 -0700 (PDT) In-Reply-To: <5171CA29.7000500@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Alex Elder Cc: ceph-devel On 04/19/2013 03:50 PM, Alex Elder wrote: > Define a new function zero_pages() that zeroes a range of memory > defined by a page array, along the lines of zero_bio_chain(). It > saves and the irq flags like bvec_kmap_irq() does, though I'm not > sure at this point that it's necessary. It doesn't seem necessary to me. I don't see anything else doing an irq save+restore around a k(un)map_atomic. Other than that, looks good. Reviewed-by: Josh Durgin > Update rbd_img_obj_request_read_callback() to use the new function > if the object request contains page rather than bio data. > > For the moment, only bio data is used for osd READ ops. > > Signed-off-by: Alex Elder > --- > drivers/block/rbd.c | 55 > +++++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 47 insertions(+), 8 deletions(-) > > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > index 894af4f..ac9abab 100644 > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -971,6 +971,37 @@ static void zero_bio_chain(struct bio *chain, int > start_ofs) > } > > /* > + * similar to zero_bio_chain(), zeros data defined by a page array, > + * starting at the given byte offset from the start of the array and > + * continuing up to the given end offset. The pages array is > + * assumed to be big enough to hold all bytes up to the end. > + */ > +static void zero_pages(struct page **pages, u64 offset, u64 end) > +{ > + struct page **page = &pages[offset >> PAGE_SHIFT]; > + > + rbd_assert(end > offset); > + rbd_assert(end - offset <= (u64)SIZE_MAX); > + while (offset < end) { > + size_t page_offset; > + size_t length; > + unsigned long flags; > + void *kaddr; > + > + page_offset = (size_t)(offset & ~PAGE_MASK); > + length = min(PAGE_SIZE - page_offset, (size_t)(end - offset)); > + local_irq_save(flags); > + kaddr = kmap_atomic(*page); > + memset(kaddr + page_offset, 0, length); > + kunmap_atomic(kaddr); > + local_irq_restore(flags); > + > + offset += length; > + page++; > + } > +} > + > +/* > * Clone a portion of a bio, starting at the given byte offset > * and continuing for the number of bytes indicated. > */ > @@ -1352,9 +1383,12 @@ static bool img_request_layered_test(struct > rbd_img_request *img_request) > static void > rbd_img_obj_request_read_callback(struct rbd_obj_request *obj_request) > { > + u64 xferred = obj_request->xferred; > + u64 length = obj_request->length; > + > dout("%s: obj %p img %p result %d %llu/%llu\n", __func__, > obj_request, obj_request->img_request, obj_request->result, > - obj_request->xferred, obj_request->length); > + xferred, length); > /* > * ENOENT means a hole in the image. We zero-fill the > * entire length of the request. A short read also implies > @@ -1362,15 +1396,20 @@ rbd_img_obj_request_read_callback(struct > rbd_obj_request *obj_request) > * update the xferred count to indicate the whole request > * was satisfied. > */ > - BUG_ON(obj_request->type != OBJ_REQUEST_BIO); > + rbd_assert(obj_request->type != OBJ_REQUEST_NODATA); > if (obj_request->result == -ENOENT) { > - zero_bio_chain(obj_request->bio_list, 0); > + if (obj_request->type == OBJ_REQUEST_BIO) > + zero_bio_chain(obj_request->bio_list, 0); > + else > + zero_pages(obj_request->pages, 0, length); > obj_request->result = 0; > - obj_request->xferred = obj_request->length; > - } else if (obj_request->xferred < obj_request->length && > - !obj_request->result) { > - zero_bio_chain(obj_request->bio_list, obj_request->xferred); > - obj_request->xferred = obj_request->length; > + obj_request->xferred = length; > + } else if (xferred < length && !obj_request->result) { > + if (obj_request->type == OBJ_REQUEST_BIO) > + zero_bio_chain(obj_request->bio_list, xferred); > + else > + zero_pages(obj_request->pages, xferred, length); > + obj_request->xferred = length; > } > obj_request_done_set(obj_request); > } >