[PATCH v1 02/14] block: introduce bio_remove_last_page()
From: Ming Lei <tom.leiming@gmail.com>
Date: 2017-02-24 15:44:20
Also in:
linux-block, lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
MD need this helper to remove the last added page, so introduce it. Signed-off-by: Ming Lei <tom.leiming@gmail.com> --- block/bio.c | 23 +++++++++++++++++++++++ include/linux/bio.h | 1 + 2 files changed, 24 insertions(+)
diff --git a/block/bio.c b/block/bio.c
index 5eec5e08417f..0ce7ffcd7939 100644
--- a/block/bio.c
+++ b/block/bio.c@@ -837,6 +837,29 @@ int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page EXPORT_SYMBOL(bio_add_pc_page); /** + * bio_remove_last_page - remove the last added page + * @bio: destination bio + * + * Attempt to remove the last added page from the bio_vec maplist. + */ +void bio_remove_last_page(struct bio *bio) +{ + /* + * cloned bio must not modify vec list + */ + if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED))) + return; + + if (bio->bi_vcnt > 0) { + struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; + + bio->bi_iter.bi_size -= bv->bv_len; + bio->bi_vcnt--; + } +} +EXPORT_SYMBOL(bio_remove_last_page); + +/** * bio_add_page - attempt to add page to bio * @bio: destination bio * @page: page to add
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 3364b3ed90e7..32aeb493d1fe 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h@@ -443,6 +443,7 @@ extern void bio_init(struct bio *bio, struct bio_vec *table, extern void bio_reset(struct bio *); void bio_chain(struct bio *, struct bio *); +extern void bio_remove_last_page(struct bio *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);
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2.7.4