From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: [PATCH v2 02/26] block: Add bio_advance() Date: Mon, 15 Oct 2012 13:09:05 -0700 Message-ID: <1350331769-14856-32-git-send-email-koverstreet@google.com> References: <1350331769-14856-1-git-send-email-koverstreet@google.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1350331769-14856-1-git-send-email-koverstreet@google.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com Cc: tj@kernel.org, axboe@kernel.dk, Kent Overstreet List-Id: linux-bcache@vger.kernel.org This is prep work for immutable bio vecs; we first want to centralize where bvecs are modified. Next two patches convert some existing code to use this function. Signed-off-by: Kent Overstreet CC: Jens Axboe --- fs/bio.c | 41 +++++++++++++++++++++++++++++++++++++++++ include/linux/bio.h | 2 ++ 2 files changed, 43 insertions(+) diff --git a/fs/bio.c b/fs/bio.c index 4783e31..07587c0 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -750,6 +750,47 @@ int bio_add_page(struct bio *bio, struct page *page, unsigned int len, } EXPORT_SYMBOL(bio_add_page); +/** + * bio_advance - increment/complete a bio by some number of bytes + * @bio: bio to advance + * @bytes: number of bytes to complete + * + * This updates bi_sector, bi_size and bi_idx; if the number of bytes to + * complete doesn't align with a bvec boundary, then bv_len and bv_offset will + * be updated on the last bvec as well. + * + * @bio will then represent the remaining, uncompleted portion of the io. + */ +void bio_advance(struct bio *bio, unsigned bytes) +{ + if (bio_integrity(bio)) + bio_integrity_advance(bio, bytes); + + bio->bi_sector += bytes >> 0; + bio->bi_size -= bytes; + + if (!bio->bi_size) + return; + + while (bytes) { + if (unlikely(bio->bi_idx >= bio->bi_vcnt)) { + printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", + __func__, bio->bi_idx, bio->bi_vcnt); + break; + } + + if (bytes >= bio_iovec(bio)->bv_len) { + bytes -= bio_iovec(bio)->bv_len; + bio->bi_idx++; + } else { + bio_iovec(bio)->bv_len -= bytes; + bio_iovec(bio)->bv_offset += bytes; + bytes = 0; + } + } +} +EXPORT_SYMBOL(bio_advance); + struct bio_map_data { struct bio_vec *iovecs; struct sg_iovec *sgvecs; diff --git a/include/linux/bio.h b/include/linux/bio.h index 7873465..6763cdf 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -248,6 +248,8 @@ extern void bio_endio(struct bio *, int); struct request_queue; extern int bio_phys_segments(struct request_queue *, struct bio *); +void bio_advance(struct bio *, unsigned); + extern void bio_init(struct bio *); extern void bio_reset(struct bio *); -- 1.7.12