[PATCH 27/60] block: introduce BIO_SP_MAX_SECTORS

[Ming Lei]

This macro is needed when one multipage bvec based bio is
converted to singlepage bvec based bio, for example, bio bounce
requires singlepage bvec.

Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
 include/linux/bio.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 8634bd24984c..fa71f6a57f81 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -40,6 +40,9 @@
 
 #define BIO_MAX_PAGES		256
 
+/* Max sectors of bio with singlepage bvec */
+#define BIO_SP_MAX_SECTORS     (BIO_MAX_PAGES * (PAGE_SIZE >> 9))
+
 #define bio_prio(bio)			(bio)->bi_ioprio
 #define bio_set_prio(bio, prio)		((bio)->bi_ioprio = prio)
 
-- 
2.7.4