[PATCH 3/3] block: move same page handling from __bio_add_pc_page to the callers

[Christoph Hellwig]

Hiding page refcount manipulation inside a low-level bio helper is
somewhat awkward.  Instead return the same page information to the
callers, where it fits in much better.

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 block/bio.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 1db626f99bcb..631b590a479f 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -668,7 +668,7 @@ static bool bio_try_merge_pc_page(struct request_queue *q, 
struct bio *bio,
  *     @page: page to add
  *     @len: vec entry length
  *     @offset: vec entry offset
- *     @put_same_page: put the page if it is same with last added page
+ *     @same_page: return if the merge happen inside the same page
  *
  *     Attempt to add a page to the bio_vec maplist. This can fail for a
  *     number of reasons, such as the bio being full or target block device
@@ -679,10 +679,9 @@ static bool bio_try_merge_pc_page(struct request_queue *q, 
struct bio *bio,
  */
 static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
                struct page *page, unsigned int len, unsigned int offset,
-               bool put_same_page)
+               bool *same_page)
 {
        struct bio_vec *bvec;
-       bool same_page = false;
 
        /*
         * cloned bio must not modify vec list
@@ -694,12 +693,8 @@ static int __bio_add_pc_page(struct request_queue *q, 
struct bio *bio,
                return 0;
 
        if (bio->bi_vcnt > 0) {
-               if (bio_try_merge_pc_page(q, bio, page, len, offset,
-                               &same_page)) {
-                       if (put_same_page && same_page)
-                               put_page(page);
+               if (bio_try_merge_pc_page(q, bio, page, len, offset, same_page))
                        return len;
-               }
 
                /*
                 * If the queue doesn't support SG gaps and adding this segment
@@ -728,7 +723,8 @@ static int __bio_add_pc_page(struct request_queue *q, 
struct bio *bio,
 int bio_add_pc_page(struct request_queue *q, struct bio *bio,
                struct page *page, unsigned int len, unsigned int offset)
 {
-       return __bio_add_pc_page(q, bio, page, len, offset, false);
+       bool same_page = false;
+       return __bio_add_pc_page(q, bio, page, len, offset, &same_page);
 }
 EXPORT_SYMBOL(bio_add_pc_page);
 
@@ -1369,13 +1365,17 @@ struct bio *bio_map_user_iov(struct request_queue *q,
                        for (j = 0; j < npages; j++) {
                                struct page *page = pages[j];
                                unsigned int n = PAGE_SIZE - offs;
+                               bool same_page = false;
 
                                if (n > bytes)
                                        n = bytes;
 
                                if (!__bio_add_pc_page(q, bio, page, n, offs,
-                                                       true))
+                                               &same_page)) {
+                                       if (same_page)
+                                               put_page(page);
                                        break;
+                               }
 
                                added += n;
                                bytes -= n;
-- 
2.20.1