| Message ID | 20180530095813.31245-2-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, May 30, 2018 at 5:58 PM, Christoph Hellwig <hch@lst.de> wrote: > 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 <hch@lst.de> > Reviewed-by: Jens Axboe <axboe@kernel.dk> > Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> > --- > 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 *, > -- > 2.17.0 > Looks fine: Reviewed-by: Ming Lei <ming.lei@redhat.com>
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 *,