DDF requires RAID6 calculations over different devices in a different
order.
For md/raid6, we calculate over just the data devices, starting
immediately after the 'Q' block.
For ddf/raid6 we calculate over all devices, using zeros in place of
the P and Q blocks.
This requires unfortunately complex loops...
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
drivers/md/raid5.c | 62 +++++++++++++++++++++++++++++---------------
include/linux/raid/raid5.h | 1 +
2 files changed, 42 insertions(+), 21 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index b26b637..f1dbfc4 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -133,6 +133,10 @@ static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
/* Find first data disk in a raid6 stripe */
static inline int raid6_d0(struct stripe_head *sh)
{
+ if (sh->ddf_layout)
+ /* ddf always start from first device */
+ return 0;
+ /* md starts just after Q block */
if (sh->qd_idx == sh->disks - 1)
return 0;
else
@@ -1248,6 +1252,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
unsigned long chunk_number;
unsigned int chunk_offset;
int pd_idx, qd_idx;
+ int ddf_layout = 0;
sector_t new_sector;
int sectors_per_chunk = conf->chunk_size >> 9;
int raid_disks = previous ? conf->previous_raid_disks
@@ -1367,6 +1372,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
qd_idx = 0;
} else if (*dd_idx >= pd_idx)
(*dd_idx) += 2; /* D D P Q D */
+ ddf_layout = 1;
break;
case ALGORITHM_ROTATING_N_RESTART:
@@ -1381,6 +1387,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
qd_idx = 0;
} else if (*dd_idx >= pd_idx)
(*dd_idx) += 2; /* D D P Q D */
+ ddf_layout = 1;
break;
case ALGORITHM_ROTATING_N_CONTINUE:
@@ -1388,6 +1395,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
pd_idx = raid_disks - 1 - (stripe % raid_disks);
qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
+ ddf_layout = 1;
break;
case ALGORITHM_LEFT_ASYMMETRIC_6:
@@ -1435,6 +1443,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
if (sh) {
sh->pd_idx = pd_idx;
sh->qd_idx = qd_idx;
+ sh->ddf_layout = ddf_layout;
}
/*
* Finally, compute the new sector number
@@ -1623,9 +1632,10 @@ static void compute_parity6(struct stripe_head *sh, int method)
{
raid6_conf_t *conf = sh->raid_conf;
int i, pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
+ int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
struct bio *chosen;
/**** FIX THIS: This could be very bad if disks is close to 256 ****/
- void *ptrs[disks];
+ void *ptrs[syndrome_disks+2];
pd_idx = sh->pd_idx;
qd_idx = sh->qd_idx;
@@ -1672,20 +1682,23 @@ static void compute_parity6(struct stripe_head *sh, int method)
count = 0;
i = d0_idx;
do {
+ const void *dblk = sh->ddf_layout ? raid6_empty_zero_page : NULL;
if (i == sh->pd_idx)
- ptrs[disks-2] = page_address(sh->dev[i].page);
+ ptrs[syndrome_disks] = page_address(sh->dev[i].page);
else if (i == sh->qd_idx)
- ptrs[disks-1] = page_address(sh->dev[i].page);
+ ptrs[syndrome_disks+1] = page_address(sh->dev[i].page);
else {
- ptrs[count++] = page_address(sh->dev[i].page);
+ dblk = page_address(sh->dev[i].page);
if (!test_bit(R5_UPTODATE, &sh->dev[i].flags))
printk("block %d/%d not uptodate on parity calc\n", i,count);
}
+ if (dblk)
+ ptrs[count++] = (void*)dblk;
i = raid6_next_disk(i, disks);
} while (i != d0_idx);
- BUG_ON(count+2 != disks);
+ BUG_ON(count != syndrome_disks);
- raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
+ raid6_call.gen_syndrome(syndrome_disks, STRIPE_SIZE, ptrs);
switch(method) {
case RECONSTRUCT_WRITE:
@@ -1743,29 +1756,35 @@ static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
{
int i, count, disks = sh->disks;
+ int syndrome_disks = sh->ddf_layout ? disks : disks-2;
int d0_idx = raid6_d0(sh);
int faila = -1, failb = -1;
/**** FIX THIS: This could be very bad if disks is close to 256 ****/
- void *ptrs[disks];
+ void *ptrs[syndrome_disks+2];
count = 0;
i = d0_idx;
do {
- int slot;
- if (i == sh->pd_idx)
- slot = disks-2;
- else if (i == sh->qd_idx)
- slot = disks-1;
- else
- slot = count++;
- ptrs[slot] = page_address(sh->dev[i].page);
+ const void *dblk = sh->ddf_layout ? raid6_empty_zero_page : NULL;
+ int slot = count;
+ if (i == sh->pd_idx) {
+ slot = syndrome_disks;
+ ptrs[slot] = page_address(sh->dev[i].page);
+ } else if (i == sh->qd_idx) {
+ slot = syndrome_disks+1;
+ ptrs[slot] = page_address(sh->dev[i].page);
+ } else
+ dblk = page_address(sh->dev[i].page);
+ if (dblk)
+ ptrs[count++] = (void*)dblk;
+
if (i == dd_idx1)
faila = slot;
if (i == dd_idx2)
failb = slot;
i = raid6_next_disk(i, disks);
} while (i != d0_idx);
- BUG_ON(count+2 != disks);
+ BUG_ON(count != syndrome_disks);
BUG_ON(faila == failb);
if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
@@ -1774,9 +1793,9 @@ static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
(unsigned long long)sh->sector, dd_idx1, dd_idx2,
faila, failb);
- if ( failb == disks-1 ) {
+ if ( failb == syndrome_disks+1 ) {
/* Q disk is one of the missing disks */
- if ( faila == disks-2 ) {
+ if ( faila == syndrome_disks ) {
/* Missing P+Q, just recompute */
compute_parity6(sh, UPDATE_PARITY);
return;
@@ -1791,12 +1810,13 @@ static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
}
/* We're missing D+P or D+D; */
- if (failb == disks-2) {
+ if (failb == syndrome_disks) {
/* We're missing D+P. */
- raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
+ raid6_datap_recov(syndrome_disks+2, STRIPE_SIZE, faila, ptrs);
} else {
/* We're missing D+D. */
- raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
+ raid6_2data_recov(syndrome_disks+2, STRIPE_SIZE, faila, failb,
+ ptrs);
}
/* Both the above update both missing blocks */
diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h
index 4d43b08..3adda05 100644
--- a/include/linux/raid/raid5.h
+++ b/include/linux/raid/raid5.h
@@ -202,6 +202,7 @@ struct stripe_head {
sector_t sector; /* sector of this row */
short pd_idx; /* parity disk index */
short qd_idx; /* 'Q' disk index for raid6 */
+ short ddf_layout; /* use DDF ordering to calculate Q */
unsigned long state; /* state flags */
atomic_t count; /* nr of active thread/requests */
spinlock_t lock;
--
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