--- /dev/null
+From 67cc2b8165857ba019920d1f00d64bcc4140075d Mon Sep 17 00:00:00 2001
+From: NeilBrown <neilb@suse.de>
+Date: Tue, 31 Mar 2009 14:39:38 +1100
+Subject: [PATCH] md/raid5: finish support for DDF/raid6
+
+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@suse.de>
+---
+ drivers/md/raid5.c | 58 +++++++++++++++++++++++++++++++--------------
+ include/linux/raid/raid5.h | 1
+ 2 files changed, 41 insertions(+), 18 deletions(-)
+
+--- linux-2.6.27-SLE11_BRANCH.orig/drivers/md/raid5.c
++++ linux-2.6.27-SLE11_BRANCH/drivers/md/raid5.c
+@@ -138,6 +138,10 @@ static inline void raid5_set_bi_hw_segme
+ /* 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
+@@ -154,13 +158,15 @@ static inline int raid6_next_disk(int di
+ * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
+ * is raid_disks-1. This help does that mapping.
+ */
+-static int raid6_idx_to_slot(int idx, struct stripe_head *sh, int *count)
++static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
++ int *count, int syndrome_disks)
+ {
+ int slot;
++
+ if (idx == sh->pd_idx)
+- return sh->disks - 2;
++ return syndrome_disks;
+ if (idx == sh->qd_idx)
+- return sh->disks - 1;
++ return syndrome_disks + 1;
+ slot = (*count)++;
+ return slot;
+ }
+@@ -1269,6 +1275,7 @@ static sector_t raid5_compute_sector(rai
+ 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
+@@ -1388,6 +1395,7 @@ static sector_t raid5_compute_sector(rai
+ 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:
+@@ -1402,6 +1410,7 @@ static sector_t raid5_compute_sector(rai
+ 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:
+@@ -1409,6 +1418,7 @@ static sector_t raid5_compute_sector(rai
+ 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:
+@@ -1456,6 +1466,7 @@ static sector_t raid5_compute_sector(rai
+ if (sh) {
+ sh->pd_idx = pd_idx;
+ sh->qd_idx = qd_idx;
++ sh->ddf_layout = ddf_layout;
+ }
+ /*
+ * Finally, compute the new sector number
+@@ -1644,9 +1655,10 @@ static void compute_parity6(struct strip
+ {
+ 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;
+@@ -1689,23 +1701,28 @@ static void compute_parity6(struct strip
+ }
+
+ /* Note that unlike RAID-5, the ordering of the disks matters greatly.*/
+- /* FIX: Is this ordering of drives even remotely optimal? */
++
++ for (i = 0; i < disks; i++)
++ ptrs[i] = (void *)raid6_empty_zero_page;
++
+ count = 0;
+ i = d0_idx;
+ do {
+- int slot = raid6_idx_to_slot(i, sh, &count);
++ int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
++
+ ptrs[slot] = page_address(sh->dev[i].page);
+- if (slot < sh->disks - 2 &&
++ if (slot < syndrome_disks &&
+ !test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
+ printk(KERN_ERR "block %d/%d not uptodate "
+ "on parity calc\n", i, count);
+ BUG();
+ }
++
+ 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+2, STRIPE_SIZE, ptrs);
+
+ switch(method) {
+ case RECONSTRUCT_WRITE:
+@@ -1763,24 +1780,28 @@ static void compute_block_1(struct strip
+ 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];
+
++ for (i = 0; i < disks ; i++)
++ ptrs[i] = (void *)raid6_empty_zero_page;
+ count = 0;
+ i = d0_idx;
+ do {
+- int slot;
+- slot = raid6_idx_to_slot(i, sh, &count);
++ int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
++
+ ptrs[slot] = page_address(sh->dev[i].page);
++
+ 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; }
+@@ -1789,9 +1810,9 @@ static void compute_block_2(struct strip
+ (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;
+@@ -1806,12 +1827,13 @@ static void compute_block_2(struct strip
+ }
+
+ /* 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 */
+--- linux-2.6.27-SLE11_BRANCH.orig/include/linux/raid/raid5.h
++++ linux-2.6.27-SLE11_BRANCH/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;
projects / people / teissler / ipfire-2.x.git / blobdiff