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md/async: don't pass a memory pointer as a page pointer.

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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>
This commit is contained in:
NeilBrown 2009-10-16 16:40:25 +11:00
parent 5e5e3e78ed
commit 5dd33c9a4c
3 changed files with 17 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
crypto/async_tx/async_pq.c
View File

@ -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,

16
crypto/async_tx/async_raid6_recov.c
View File

@ -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);
@ -338,7 +338,10 @@ 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++)
ptrs[i] = page_address(blocks[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);
@ -398,7 +401,10 @@ async_raid6_datap_recov(int disks, size_t bytes, int faila,
async_tx_quiesce(&submit->depend_tx);
for (i = 0; i < disks; i++)
ptrs[i] = page_address(blocks[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

4
drivers/md/raid5.c
View File

@ -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 {