[PATCH v3 08/49] block: comment on bio_alloc_pages()

[Ming Lei]

This patch adds comment on usage of bio_alloc_pages().

Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
 block/bio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index e241bbc49f14..826b5d173416 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -981,7 +981,9 @@ EXPORT_SYMBOL(bio_advance);
  * @bio: bio to allocate pages for
  * @gfp_mask: flags for allocation
  *
- * Allocates pages up to @bio->bi_vcnt.
+ * Allocates pages up to @bio->bi_vcnt, and this function should only
+ * be called on a new initialized bio, which means all pages aren't added
+ * to the bio via bio_add_page() yet.
  *
  * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
  * freed.
-- 
2.9.4