Commit 5dd33c9a authored by NeilBrown's avatar NeilBrown
Browse files

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: default avatarNeilBrown <neilb@suse.de>
parent 5e5e3e78

crypto/async_tx/async_pq.c

+4 −11
Original line number Diff line number Diff line
@@ -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 @@ do_async_gen_syndrome(struct dma_chan *chan, struct page **blocks, 
	 * 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 @@ do_sync_gen_syndrome(struct page **blocks, unsigned int offset, int disks, 
		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 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks, 
		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,

crypto/async_tx/async_raid6_recov.c

+11 −5
Original line number Diff line number Diff line
@@ -263,10 +263,10 @@ __2data_recov_n(int disks, size_t bytes, int faila, int failb, 
	 * delta p and delta q

	 */

	dp = blocks[faila];

	blocks[faila] = (void *)raid6_empty_zero_page;

	blocks[faila] = NULL;

	blocks[disks-2] = dp;

	dq = blocks[failb];

	blocks[failb] = (void *)raid6_empty_zero_page;

	blocks[failb] = NULL;

	blocks[disks-1] = dq;



	init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
@@ -338,6 +338,9 @@ async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb, 


		async_tx_quiesce(&submit->depend_tx);

		for (i = 0; i < disks; i++)

			if (blocks[i] == NULL)

				ptrs[i] = (void*)raid6_empty_zero_page;

			else

				ptrs[i] = page_address(blocks[i]);



		raid6_2data_recov(disks, bytes, faila, failb, ptrs);
@@ -398,6 +401,9 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila, 


		async_tx_quiesce(&submit->depend_tx);

		for (i = 0; i < disks; i++)

			if (blocks[i] == NULL)

				ptrs[i] = (void*)raid6_empty_zero_page;

			else

				ptrs[i] = page_address(blocks[i]);



		raid6_datap_recov(disks, bytes, faila, ptrs);
@@ -414,7 +420,7 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila, 
	 * Use the dead data page as temporary storage for delta q

	 */

	dq = blocks[faila];

	blocks[faila] = (void *)raid6_empty_zero_page;

	blocks[faila] = NULL;

	blocks[disks-1] = dq;



	/* in the 4 disk case we only need to perform a single source

drivers/md/raid5.c

+2 −2
Original line number Diff line number Diff line
@@ -720,7 +720,7 @@ static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh) 
	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 @@ ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu) 
	 * 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 {

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