[PATCH v6 8/8] block: mark BIO_MAX_SIZE as obsolete

[Ming Lei]

Some in-tree drivers may use big bio which size is more
than BIO_MAX_SIZE, also the macro is seldom used in tree.

So mark it as obsolete now, and it doesn't make sense
after multipage bvec is introduced.

Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
---
 include/linux/bio.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index fb59a06..b284595 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -41,6 +41,13 @@
 #endif
 
 #define BIO_MAX_PAGES		256
+
+/*
+ * This is obsolete now and shouldn't be used, and the macro
+ * doesn't make any sense especially when multipage bvecs is
+ * supported. Even now some drivers may pass big bio which size
+ * is more than the value, such as bcache.
+ */
 #define BIO_MAX_SIZE		(BIO_MAX_PAGES << PAGE_SHIFT)
 
 /*
-- 
1.9.1