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>
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

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 {