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/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
index b88db6d..9ab1ce4 100644
--- a/crypto/async_tx/async_pq.c
+++ b/crypto/async_tx/async_pq.c
@@ -30,11 +30,6 @@
*/
static struct page *scribble;
-static bool is_raid6_zero_block(struct page *p)
-{
- return p == (void *) raid6_empty_zero_page;
-}
-
/* the struct page *blocks[] parameter passed to async_gen_syndrome()
* and async_syndrome_val() contains the 'P' destination address at
* blocks[disks-2] and the 'Q' destination address at blocks[disks-1]
@@ -83,7 +78,7 @@
* sources and update the coefficients accordingly
*/
for (i = 0, idx = 0; i < src_cnt; i++) {
- if (is_raid6_zero_block(blocks[i]))
+ if (blocks[i] == NULL)
continue;
dma_src[idx] = dma_map_page(dma->dev, blocks[i], offset, len,
DMA_TO_DEVICE);
@@ -160,9 +155,9 @@
srcs = (void **) blocks;
for (i = 0; i < disks; i++) {
- if (is_raid6_zero_block(blocks[i])) {
+ if (blocks[i] == NULL) {
BUG_ON(i > disks - 3); /* P or Q can't be zero */
- srcs[i] = blocks[i];
+ srcs[i] = (void*)raid6_empty_zero_page;
} else
srcs[i] = page_address(blocks[i]) + offset;
}
@@ -290,12 +285,10 @@
if (submit->flags & ASYNC_TX_FENCE)
dma_flags |= DMA_PREP_FENCE;
for (i = 0; i < disks; i++)
- if (likely(blocks[i])) {
- BUG_ON(is_raid6_zero_block(blocks[i]));
+ if (likely(blocks[i]))
dma_src[i] = dma_map_page(dev, blocks[i],
offset, len,
DMA_TO_DEVICE);
- }
for (;;) {
tx = device->device_prep_dma_pq_val(chan, pq, dma_src,