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Fri, 11 Nov 2016 04:06:54 -0800 (PST) Received: from localhost ([45.34.23.101]) by smtp.gmail.com with ESMTPSA id j68sm14691193pfk.95.2016.11.11.04.06.53 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 Nov 2016 04:06:54 -0800 (PST) From: Ming Lei To: Jens Axboe , linux-kernel@vger.kernel.org Date: Fri, 11 Nov 2016 20:05:35 +0800 Message-Id: <1478865957-25252-8-git-send-email-tom.leiming@gmail.com> In-Reply-To: <1478865957-25252-1-git-send-email-tom.leiming@gmail.com> References: <1478865957-25252-1-git-send-email-tom.leiming@gmail.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 11 Nov 2016 12:06:55 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 11 Nov 2016 12:06:55 +0000 (UTC) for IP:'209.85.192.196' DOMAIN:'mail-pf0-f196.google.com' HELO:'mail-pf0-f196.google.com' FROM:'tom.leiming@gmail.com' RCPT:'' X-RedHat-Spam-Score: -2.399 (BAYES_50, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H2, RCVD_IN_SORBS_SPAM, SPF_PASS) 209.85.192.196 mail-pf0-f196.google.com 209.85.192.196 mail-pf0-f196.google.com X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-Scanned-By: MIMEDefang 2.78 on 10.5.110.25 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 14 Nov 2016 03:25:50 -0500 Cc: Christoph Hellwig , Mike Snitzer , Ming Lei , linux-block@vger.kernel.org, "maintainer:DEVICE-MAPPER LVM, Shaohua Li , linux-raid@vger.kernel.org open list:SOFTWARE RAID Multiple DisksSUPPORT" , linux-fsdevel@vger.kernel.org, Alasdair Kergon Subject: [dm-devel] [PATCH 07/12] dm: use bvec iterator helpers to implement .get_page and .next_page X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Virus-Scanned: ClamAV using ClamSMTP Firstly we have mature bvec/bio iterator helper for iterate each page in one bio, not necessary to reinvent a wheel to do that. Secondly the coming multipage bvecs requires this patch. Also add comments about the direct access to bvec table. Signed-off-by: Ming Lei --- drivers/md/dm-io.c | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c index 0bf1a12e35fe..2ef573c220fc 100644 --- a/drivers/md/dm-io.c +++ b/drivers/md/dm-io.c @@ -162,7 +162,10 @@ struct dpages { struct page **p, unsigned long *len, unsigned *offset); void (*next_page)(struct dpages *dp); - unsigned context_u; + union { + unsigned context_u; + struct bvec_iter context_bi; + }; void *context_ptr; void *vma_invalidate_address; @@ -204,25 +207,36 @@ static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offse static void bio_get_page(struct dpages *dp, struct page **p, unsigned long *len, unsigned *offset) { - struct bio_vec *bvec = dp->context_ptr; - *p = bvec->bv_page; - *len = bvec->bv_len - dp->context_u; - *offset = bvec->bv_offset + dp->context_u; + struct bio_vec bv = bvec_iter_bvec((struct bio_vec *)dp->context_ptr, + dp->context_bi); + + *p = bv.bv_page; + *len = bv.bv_len; + *offset = bv.bv_offset; + + /* avoid to figure out it in bio_next_page() again */ + dp->context_bi.bi_sector = (sector_t)bv.bv_len; } static void bio_next_page(struct dpages *dp) { - struct bio_vec *bvec = dp->context_ptr; - dp->context_ptr = bvec + 1; - dp->context_u = 0; + unsigned int len = (unsigned int)dp->context_bi.bi_sector; + + bvec_iter_advance((struct bio_vec *)dp->context_ptr, + &dp->context_bi, len); } static void bio_dp_init(struct dpages *dp, struct bio *bio) { dp->get_page = bio_get_page; dp->next_page = bio_next_page; - dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); - dp->context_u = bio->bi_iter.bi_bvec_done; + + /* + * We just use bvec iterator to retrieve pages, so it is ok to + * access the bvec table directly here + */ + dp->context_ptr = bio->bi_io_vec; + dp->context_bi = bio->bi_iter; } /*