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-rw-r--r--block/bio.c96
-rw-r--r--include/linux/bio.h9
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 *,