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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id e12-v6si15822347plt.209.2018.05.30.02.58.21 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 30 May 2018 02:58:22 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of batv+1f4557cc97fec8e307c5+5393+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=P5096hc7; spf=pass (google.com: best guess record for domain of batv+1f4557cc97fec8e307c5+5393+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+1f4557cc97fec8e307c5+5393+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=PWyIgILGpptnPpzRp9u3DdX91CHZ1s08cAYcvNqHZA0=; b=P5096hc7x0cmjqQ4FBhbH0uJL fNYI+gZwqGtfoMdJoJJtIxV+k5M89sZYCVXfcBLdjju+Fv3xeqlQ1PSD6xtOEWMd2ldJJYo0ZCsf0 1Gjbaw4ZzAoOFASx+1ne0KF/EKRBrnAnQrcgR/G1516CMM1slBOj8WFpmEo9LmYSv1IPPZb2t6IXI KpKwiTAnERlHC0brIoO1sd+ddl4mWgudYdvT0SRCGtdpUm9q2O3b3ViVkimdd9p7yZi1x56urUSjs lQfGLySD69rsL+hDi8TNxsteY4LOHvUW90Gn6hUQdpCA/K/Jp/WU6JBaL+FSnn3opXUUTs3ksg/Re 300ntvOsg==; Received: from 213-225-38-123.nat.highway.a1.net ([213.225.38.123] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fNxs4-0006Qo-Pr; Wed, 30 May 2018 09:58:21 +0000 From: Christoph Hellwig To: linux-xfs@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 01/13] block: add a lower-level bio_add_page interface Date: Wed, 30 May 2018 11:58:01 +0200 Message-Id: <20180530095813.31245-2-hch@lst.de> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180530095813.31245-1-hch@lst.de> References: <20180530095813.31245-1-hch@lst.de> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP For the upcoming removal of buffer heads in XFS we need to keep track of the number of outstanding writeback requests per page. For this we need to know if bio_add_page merged a region with the previous bvec or not. Instead of adding additional arguments this refactors bio_add_page to be implemented using three lower level helpers which users like XFS can use directly if they care about the merge decisions. Signed-off-by: Christoph Hellwig Reviewed-by: Jens Axboe Reviewed-by: Darrick J. Wong Reviewed-by: Ming Lei --- block/bio.c | 96 +++++++++++++++++++++++++++++---------------- include/linux/bio.h | 9 +++++ 2 files changed, 72 insertions(+), 33 deletions(-) diff --git a/block/bio.c b/block/bio.c index 53e0f0a1ed94..fdf635d42bbd 100644 --- a/block/bio.c +++ b/block/bio.c @@ -773,7 +773,7 @@ int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page return 0; } - if (bio->bi_vcnt >= bio->bi_max_vecs) + if (bio_full(bio)) return 0; /* @@ -821,52 +821,82 @@ int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page EXPORT_SYMBOL(bio_add_pc_page); /** - * bio_add_page - attempt to add page to bio - * @bio: destination bio - * @page: page to add - * @len: vec entry length - * @offset: vec entry offset + * __bio_try_merge_page - try appending data to an existing bvec. + * @bio: destination bio + * @page: page to add + * @len: length of the data to add + * @off: offset of the data in @page * - * Attempt to add a page to the bio_vec maplist. This will only fail - * if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio. + * Try to add the data at @page + @off to the last bvec of @bio. This is a + * a useful optimisation for file systems with a block size smaller than the + * page size. + * + * Return %true on success or %false on failure. */ -int bio_add_page(struct bio *bio, struct page *page, - unsigned int len, unsigned int offset) +bool __bio_try_merge_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int off) { - struct bio_vec *bv; - - /* - * cloned bio must not modify vec list - */ if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED))) - return 0; + return false; - /* - * For filesystems with a blocksize smaller than the pagesize - * we will often be called with the same page as last time and - * a consecutive offset. Optimize this special case. - */ if (bio->bi_vcnt > 0) { - bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; + struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; - if (page == bv->bv_page && - offset == bv->bv_offset + bv->bv_len) { + if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) { bv->bv_len += len; - goto done; + bio->bi_iter.bi_size += len; + return true; } } + return false; +} +EXPORT_SYMBOL_GPL(__bio_try_merge_page); - if (bio->bi_vcnt >= bio->bi_max_vecs) - return 0; +/** + * __bio_add_page - add page to a bio in a new segment + * @bio: destination bio + * @page: page to add + * @len: length of the data to add + * @off: offset of the data in @page + * + * Add the data at @page + @off to @bio as a new bvec. The caller must ensure + * that @bio has space for another bvec. + */ +void __bio_add_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int off) +{ + struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt]; - bv = &bio->bi_io_vec[bio->bi_vcnt]; - bv->bv_page = page; - bv->bv_len = len; - bv->bv_offset = offset; + WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)); + WARN_ON_ONCE(bio_full(bio)); + + bv->bv_page = page; + bv->bv_offset = off; + bv->bv_len = len; - bio->bi_vcnt++; -done: bio->bi_iter.bi_size += len; + bio->bi_vcnt++; +} +EXPORT_SYMBOL_GPL(__bio_add_page); + +/** + * bio_add_page - attempt to add page to bio + * @bio: destination bio + * @page: page to add + * @len: vec entry length + * @offset: vec entry offset + * + * Attempt to add a page to the bio_vec maplist. This will only fail + * if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio. + */ +int bio_add_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int offset) +{ + if (!__bio_try_merge_page(bio, page, len, offset)) { + if (bio_full(bio)) + return 0; + __bio_add_page(bio, page, len, offset); + } return len; } EXPORT_SYMBOL(bio_add_page); diff --git a/include/linux/bio.h b/include/linux/bio.h index ce547a25e8ae..3e73c8bc25ea 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -123,6 +123,11 @@ static inline void *bio_data(struct bio *bio) return NULL; } +static inline bool bio_full(struct bio *bio) +{ + return bio->bi_vcnt >= bio->bi_max_vecs; +} + /* * will die */ @@ -470,6 +475,10 @@ void bio_chain(struct bio *, struct bio *); extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int); extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *, unsigned int, unsigned int); +bool __bio_try_merge_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int off); +void __bio_add_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int off); int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter); struct rq_map_data; extern struct bio *bio_map_user_iov(struct request_queue *,