struct dma_chan *
__async_tx_find_channel(struct async_submit_ctl *submit,
enum dma_transaction_type tx_type)
{
struct dma_async_tx_descriptor *depend_tx = submit->depend_tx;
if (depend_tx &&
dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
return depend_tx->chan;
return async_dma_find_channel(tx_type);
}
struct dma_async_tx_descriptor *
async_raid6_datap_recov(int disks, size_t bytes, int faila,
struct page **blocks, struct async_submit_ctl *submit)
{
struct dma_async_tx_descriptor *tx = NULL;
struct page *p, *q, *dq;
u8 coef;
enum async_tx_flags flags = submit->flags;
dma_async_tx_callback cb_fn = submit->cb_fn;
void *cb_param = submit->cb_param;
void *scribble = submit->scribble;
int good_srcs, good, i;
struct page *srcs[2];
pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
/* if a dma resource is not available or a scribble buffer is not
* available punt to the synchronous path. In the 'dma not
* available' case be sure to use the scribble buffer to
* preserve the content of 'blocks' as the caller intended.
*/
if (!async_dma_find_channel(DMA_PQ) || !scribble) {
void **ptrs = scribble ? scribble : (void **) blocks;
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);
async_tx_sync_epilog(submit);
return NULL;
}
good_srcs = 0;
good = -1;
for (i = 0; i < disks-2; i++) {
if (i == faila)
continue;
if (blocks[i]) {
good = i;
good_srcs++;
if (good_srcs > 1)
break;
}
}
BUG_ON(good_srcs == 0);
p = blocks[disks-2];
q = blocks[disks-1];
/* Compute syndrome with zero for the missing data page
* Use the dead data page as temporary storage for delta q
*/
dq = blocks[faila];
blocks[faila] = NULL;
blocks[disks-1] = dq;
/* in the 4-disk case we only need to perform a single source
* multiplication with the one good data block.
*/
if (good_srcs == 1) {
struct page *g = blocks[good];
init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
scribble);
tx = async_memcpy(p, g, 0, 0, bytes, submit);
init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
scribble);
tx = async_mult(dq, g, raid6_gfexp[good], bytes, submit);
} else {
init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL,
scribble);
tx = async_gen_syndrome(blocks, 0, disks, bytes, submit);
}
/* Restore pointer table */
blocks[faila] = dq;
blocks[disks-1] = q;
/* calculate g^{-faila} */
coef = raid6_gfinv[raid6_gfexp[faila]];
srcs[0] = dq;
srcs[1] = q;
init_async_submit(submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
NULL, NULL, scribble);
tx = async_xor(dq, srcs, 0, 2, bytes, submit);
init_async_submit(submit, ASYNC_TX_FENCE, tx, NULL, NULL, scribble);
tx = async_mult(dq, dq, coef, bytes, submit);
srcs[0] = p;
srcs[1] = dq;
init_async_submit(submit, flags | ASYNC_TX_XOR_DROP_DST, tx, cb_fn,
cb_param, scribble);
tx = async_xor(p, srcs, 0, 2, bytes, submit);
return tx;
}
struct dma_async_tx_descriptor *
async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
struct page **blocks, struct async_submit_ctl *submit)
{
void *scribble = submit->scribble;
int non_zero_srcs, i;
BUG_ON(faila == failb);
if (failb < faila)
swap(faila, failb);
pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);
/* if a dma resource is not available or a scribble buffer is not
* available punt to the synchronous path. In the 'dma not
* available' case be sure to use the scribble buffer to
* preserve the content of 'blocks' as the caller intended.
*/
if (!async_dma_find_channel(DMA_PQ) || !scribble) {
void **ptrs = scribble ? scribble : (void **) blocks;
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);
async_tx_sync_epilog(submit);
return NULL;
}
non_zero_srcs = 0;
for (i = 0; i < disks-2 && non_zero_srcs < 4; i++)
if (blocks[i])
non_zero_srcs++;
switch (non_zero_srcs) {
case 0:
case 1:
/* There must be at least 2 sources - the failed devices. */
BUG();
case 2:
/* dma devices do not uniformly understand a zero source pq
* operation (in contrast to the synchronous case), so
* explicitly handle the special case of a 4 disk array with
* both data disks missing.
*/
return __2data_recov_4(disks, bytes, faila, failb, blocks, submit);
case 3:
/* dma devices do not uniformly understand a single
* source pq operation (in contrast to the synchronous
* case), so explicitly handle the special case of a 5 disk
* array with 2 of 3 data disks missing.
*/
return __2data_recov_5(disks, bytes, faila, failb, blocks, submit);
default:
return __2data_recov_n(disks, bytes, faila, failb, blocks, submit);
}
}
