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-x86/dma-mapping_32.h b/include/asm-x86/dma-mapping_32.h
index 6a2d26c..55f01bd 100644
--- a/include/asm-x86/dma-mapping_32.h
+++ b/include/asm-x86/dma-mapping_32.h
@@ -45,9 +45,9 @@
WARN_ON(nents == 0 || sglist[0].length == 0);
for_each_sg(sglist, sg, nents, i) {
- BUG_ON(!sg->page);
+ BUG_ON(!sg_page(sg));
- sg->dma_address = page_to_phys(sg->page) + sg->offset;
+ sg->dma_address = sg_phys(sg);
}
flush_write_buffers();