Change table chaining layout
Change the page member of the scatterlist structure to be an unsigned
long, and encode more stuff in the lower bits:
- Bits 0 and 1 zero: this is a normal sg entry. Next sg entry is located
at sg + 1.
- Bit 0 set: this is a chain entry, the next real entry is at ->page_link
with the two low bits masked off.
- Bit 1 set: this is the final entry in the sg entry. sg_next() will return
NULL when passed such an entry.
It's thus important that sg table users use the proper accessors to get
and set the page member.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/asm-s390/scatterlist.h b/include/asm-s390/scatterlist.h
index a43b3af..eb39486 100644
--- a/include/asm-s390/scatterlist.h
+++ b/include/asm-s390/scatterlist.h
@@ -2,7 +2,7 @@
#define _ASMS390_SCATTERLIST_H
struct scatterlist {
- struct page *page;
+ unsigned long page_link;
unsigned int offset;
unsigned int length;
};