md/async: don't pass a memory pointer as a page pointer.
md/raid6 passes a list of 'struct page *' to the async_tx routines,
which then either DMA map them for offload, or take the page_address
for CPU based calculations.
For RAID6 we sometime leave 'blanks' in the list of pages.
For CPU based calcs, we want to treat theses as a page of zeros.
For offloaded calculations, we simply don't pass a page to the
hardware.
Currently the 'blanks' are encoded as a pointer to
raid6_empty_zero_page. This is a 4096 byte memory region, not a
'struct page'. This is mostly handled correctly but is rather ugly.
So change the code to pass and expect a NULL pointer for the blanks.
When taking page_address of a page, we need to check for a NULL and
in that case use raid6_empty_zero_page.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index c4366c9..dcd9e65 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -720,7 +720,7 @@
int i;
for (i = 0; i < disks; i++)
- srcs[i] = (void *)raid6_empty_zero_page;
+ srcs[i] = NULL;
count = 0;
i = d0_idx;
@@ -816,7 +816,7 @@
* slot number conversion for 'faila' and 'failb'
*/
for (i = 0; i < disks ; i++)
- blocks[i] = (void *)raid6_empty_zero_page;
+ blocks[i] = NULL;
count = 0;
i = d0_idx;
do {