md/raid6: remove expectation that Q device is immediately after P device.
Code currently assumes that the devices in a raid6 stripe are
0 1 ... N-1 P Q
in some rotated order. We will shortly add new layouts in which
this strict pattern is broken.
So remove this expectation. We still assume that the data disks
are roughly in-order. However P and Q can be inserted anywhere within
that order.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index c33073f..cb3e157 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -133,12 +133,36 @@
bio->bi_phys_segments = raid5_bi_phys_segments(bio) || (cnt << 16);
}
+/* Find first data disk in a raid6 stripe */
+static inline int raid6_d0(struct stripe_head *sh)
+{
+ if (sh->qd_idx == sh->disks - 1)
+ return 0;
+ else
+ return sh->qd_idx + 1;
+}
static inline int raid6_next_disk(int disk, int raid_disks)
{
disk++;
return (disk < raid_disks) ? disk : 0;
}
+/* When walking through the disks in a raid5, starting at raid6_d0,
+ * We need to map each disk to a 'slot', where the data disks are slot
+ * 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)
+{
+ int slot;
+ if (idx == sh->pd_idx)
+ return sh->disks - 2;
+ if (idx == sh->qd_idx)
+ return sh->disks - 1;
+ slot = (*count)++;
+ return slot;
+}
+
static void return_io(struct bio *return_bi)
{
struct bio *bi = return_bi;
@@ -196,6 +220,7 @@
}
}
}
+
static void release_stripe(struct stripe_head *sh)
{
raid5_conf_t *conf = sh->raid_conf;
@@ -274,12 +299,14 @@
}
static void raid5_build_block(struct stripe_head *sh, int i);
-static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int previous);
+static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int previous,
+ int *qd_idx);
static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
{
raid5_conf_t *conf = sh->raid_conf;
int i;
+ int qd_idx;
BUG_ON(atomic_read(&sh->count) != 0);
BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
@@ -293,7 +320,8 @@
sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
sh->sector = sector;
- sh->pd_idx = stripe_to_pdidx(sector, conf, previous);
+ sh->pd_idx = stripe_to_pdidx(sector, conf, previous, &qd_idx);
+ sh->qd_idx = qd_idx;
sh->state = 0;
@@ -1235,7 +1263,7 @@
*/
static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
int previous,
- int *dd_idx, int *pd_idx)
+ int *dd_idx, int *pd_idx, int *qd_idx)
{
long stripe;
unsigned long chunk_number;
@@ -1268,6 +1296,7 @@
/*
* Select the parity disk based on the user selected algorithm.
*/
+ *qd_idx = ~0;
switch(conf->level) {
case 4:
*pd_idx = data_disks;
@@ -1303,24 +1332,30 @@
switch (conf->algorithm) {
case ALGORITHM_LEFT_ASYMMETRIC:
*pd_idx = raid_disks - 1 - (stripe % raid_disks);
- if (*pd_idx == raid_disks-1)
+ *qd_idx = *pd_idx + 1;
+ if (*pd_idx == raid_disks-1) {
(*dd_idx)++; /* Q D D D P */
- else if (*dd_idx >= *pd_idx)
+ *qd_idx = 0;
+ } else if (*dd_idx >= *pd_idx)
(*dd_idx) += 2; /* D D P Q D */
break;
case ALGORITHM_RIGHT_ASYMMETRIC:
*pd_idx = stripe % raid_disks;
- if (*pd_idx == raid_disks-1)
+ *qd_idx = *pd_idx + 1;
+ if (*pd_idx == raid_disks-1) {
(*dd_idx)++; /* Q D D D P */
- else if (*dd_idx >= *pd_idx)
+ *qd_idx = 0;
+ } else if (*dd_idx >= *pd_idx)
(*dd_idx) += 2; /* D D P Q D */
break;
case ALGORITHM_LEFT_SYMMETRIC:
*pd_idx = raid_disks - 1 - (stripe % raid_disks);
+ *qd_idx = (*pd_idx + 1) % raid_disks;
*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
break;
case ALGORITHM_RIGHT_SYMMETRIC:
*pd_idx = stripe % raid_disks;
+ *qd_idx = (*pd_idx + 1) % raid_disks;
*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
break;
default:
@@ -1347,7 +1382,7 @@
int sectors_per_chunk = conf->chunk_size >> 9;
sector_t stripe;
int chunk_offset;
- int chunk_number, dummy1, dummy2, dd_idx = i;
+ int chunk_number, dummy1, dummy2, dummy3, dd_idx = i;
sector_t r_sector;
@@ -1378,7 +1413,7 @@
}
break;
case 6:
- if (i == raid6_next_disk(sh->pd_idx, raid_disks))
+ if (i == sh->qd_idx)
return 0; /* It is the Q disk */
switch (conf->algorithm) {
case ALGORITHM_LEFT_ASYMMETRIC:
@@ -1411,7 +1446,7 @@
check = raid5_compute_sector(conf, r_sector,
(raid_disks != conf->raid_disks),
- &dummy1, &dummy2);
+ &dummy1, &dummy2, &dummy3);
if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
printk(KERN_ERR "compute_blocknr: map not correct\n");
return 0;
@@ -1480,13 +1515,14 @@
static void compute_parity6(struct stripe_head *sh, int method)
{
raid5_conf_t *conf = sh->raid_conf;
- int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
+ int i, pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
struct bio *chosen;
/**** FIX THIS: This could be very bad if disks is close to 256 ****/
void *ptrs[disks];
- qd_idx = raid6_next_disk(pd_idx, disks);
- d0_idx = raid6_next_disk(qd_idx, disks);
+ pd_idx = sh->pd_idx;
+ qd_idx = sh->qd_idx;
+ d0_idx = raid6_d0(sh);
pr_debug("compute_parity, stripe %llu, method %d\n",
(unsigned long long)sh->sector, method);
@@ -1524,22 +1560,22 @@
set_bit(R5_UPTODATE, &sh->dev[i].flags);
}
-// switch(method) {
-// case RECONSTRUCT_WRITE:
-// case CHECK_PARITY:
-// case UPDATE_PARITY:
- /* Note that unlike RAID-5, the ordering of the disks matters greatly. */
- /* FIX: Is this ordering of drives even remotely optimal? */
- count = 0;
- i = d0_idx;
- do {
- ptrs[count++] = page_address(sh->dev[i].page);
- if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
- printk("block %d/%d not uptodate on parity calc\n", i,count);
- i = raid6_next_disk(i, disks);
- } while ( i != d0_idx );
-// break;
-// }
+ /* Note that unlike RAID-5, the ordering of the disks matters greatly.*/
+ /* FIX: Is this ordering of drives even remotely optimal? */
+ count = 0;
+ i = d0_idx;
+ do {
+ int slot = raid6_idx_to_slot(i, sh, &count);
+ ptrs[slot] = page_address(sh->dev[i].page);
+ if (slot < sh->disks - 2 &&
+ !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);
raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
@@ -1563,8 +1599,7 @@
{
int i, count, disks = sh->disks;
void *ptr[MAX_XOR_BLOCKS], *dest, *p;
- int pd_idx = sh->pd_idx;
- int qd_idx = raid6_next_disk(pd_idx, disks);
+ int qd_idx = sh->qd_idx;
pr_debug("compute_block_1, stripe %llu, idx %d\n",
(unsigned long long)sh->sector, dd_idx);
@@ -1600,21 +1635,31 @@
static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
{
int i, count, disks = sh->disks;
- int pd_idx = sh->pd_idx;
- int qd_idx = raid6_next_disk(pd_idx, disks);
- int d0_idx = raid6_next_disk(qd_idx, disks);
- int faila, failb;
+ 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];
- /* faila and failb are disk numbers relative to d0_idx */
- /* pd_idx become disks-2 and qd_idx become disks-1 */
- faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
- failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
+ count = 0;
+ i = d0_idx;
+ do {
+ int slot;
+ slot = raid6_idx_to_slot(i, sh, &count);
+ 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(faila == failb);
if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
pr_debug("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
- (unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
+ (unsigned long long)sh->sector, dd_idx1, dd_idx2,
+ faila, failb);
if ( failb == disks-1 ) {
/* Q disk is one of the missing disks */
@@ -1624,39 +1669,26 @@
return;
} else {
/* We're missing D+Q; recompute D from P */
- compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0);
+ compute_block_1(sh, ((dd_idx1 == sh->qd_idx) ?
+ dd_idx2 : dd_idx1),
+ 0);
compute_parity6(sh, UPDATE_PARITY); /* Is this necessary? */
return;
}
}
- /* We're missing D+P or D+D; build pointer table */
- {
- /**** FIX THIS: This could be very bad if disks is close to 256 ****/
- void *ptrs[disks];
-
- count = 0;
- i = d0_idx;
- do {
- ptrs[count++] = page_address(sh->dev[i].page);
- i = raid6_next_disk(i, disks);
- if (i != dd_idx1 && i != dd_idx2 &&
- !test_bit(R5_UPTODATE, &sh->dev[i].flags))
- printk("compute_2 with missing block %d/%d\n", count, i);
- } while ( i != d0_idx );
-
- if ( failb == disks-2 ) {
- /* We're missing D+P. */
- raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
- } else {
- /* We're missing D+D. */
- raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
- }
-
- /* Both the above update both missing blocks */
- set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
- set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
+ /* We're missing D+P or D+D; */
+ if (failb == disks-2) {
+ /* We're missing D+P. */
+ raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
+ } else {
+ /* We're missing D+D. */
+ raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
}
+
+ /* Both the above update both missing blocks */
+ set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
+ set_bit(R5_UPTODATE, &sh->dev[dd_idx2].flags);
}
static void
@@ -1811,7 +1843,8 @@
memcmp(a, a+4, STRIPE_SIZE-4)==0);
}
-static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int previous)
+static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int previous,
+ int *qd_idxp)
{
int sectors_per_chunk = conf->chunk_size >> 9;
int pd_idx, dd_idx;
@@ -1822,7 +1855,7 @@
stripe * (disks - conf->max_degraded)
*sectors_per_chunk + chunk_offset,
previous,
- &dd_idx, &pd_idx);
+ &dd_idx, &pd_idx, qd_idxp);
return pd_idx;
}
@@ -2481,12 +2514,13 @@
clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
for (i = 0; i < sh->disks; i++)
if (i != sh->pd_idx && (!r6s || i != r6s->qd_idx)) {
- int dd_idx, pd_idx, j;
+ int dd_idx, pd_idx, qd_idx, j;
struct stripe_head *sh2;
sector_t bn = compute_blocknr(sh, i);
- sector_t s = raid5_compute_sector(conf, bn, 0,
- &dd_idx, &pd_idx);
+ sector_t s =
+ raid5_compute_sector(conf, bn, 0,
+ &dd_idx, &pd_idx, &qd_idx);
sh2 = get_active_stripe(conf, s, 0, 1);
if (sh2 == NULL)
/* so far only the early blocks of this stripe
@@ -2510,8 +2544,7 @@
set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
for (j = 0; j < conf->raid_disks; j++)
if (j != sh2->pd_idx &&
- (!r6s || j != raid6_next_disk(sh2->pd_idx,
- sh2->disks)) &&
+ (!r6s || j != sh2->qd_idx) &&
!test_bit(R5_Expanded, &sh2->dev[j].flags))
break;
if (j == conf->raid_disks) {
@@ -2771,9 +2804,11 @@
if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
!sh->reconstruct_state) {
+ int qd_idx;
/* Need to write out all blocks after computing parity */
sh->disks = conf->raid_disks;
- sh->pd_idx = stripe_to_pdidx(sh->sector, conf, 0);
+ sh->pd_idx = stripe_to_pdidx(sh->sector, conf, 0, &qd_idx);
+ sh->qd_idx = qd_idx;
schedule_reconstruction5(sh, &s, 1, 1);
} else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
clear_bit(STRIPE_EXPAND_READY, &sh->state);
@@ -2814,7 +2849,7 @@
struct r5dev *dev, *pdev, *qdev;
mdk_rdev_t *blocked_rdev = NULL;
- r6s.qd_idx = raid6_next_disk(pd_idx, disks);
+ r6s.qd_idx = sh->qd_idx;
pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
"pd_idx=%d, qd_idx=%d\n",
(unsigned long long)sh->sector, sh->state,
@@ -2990,8 +3025,10 @@
if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
/* Need to write out all blocks after computing P&Q */
+ int qd_idx;
sh->disks = conf->raid_disks;
- sh->pd_idx = stripe_to_pdidx(sh->sector, conf, 0);
+ sh->pd_idx = stripe_to_pdidx(sh->sector, conf, 0, &qd_idx);
+ sh->qd_idx = qd_idx;
compute_parity6(sh, RECONSTRUCT_WRITE);
for (i = conf->raid_disks ; i-- ; ) {
set_bit(R5_LOCKED, &sh->dev[i].flags);
@@ -3263,7 +3300,7 @@
{
mddev_t *mddev = q->queuedata;
raid5_conf_t *conf = mddev_to_conf(mddev);
- unsigned int dd_idx, pd_idx;
+ unsigned int dd_idx, pd_idx, qd_idx;
struct bio* align_bi;
mdk_rdev_t *rdev;
@@ -3288,7 +3325,7 @@
*/
align_bi->bi_sector = raid5_compute_sector(conf, raid_bio->bi_sector,
0,
- &dd_idx, &pd_idx);
+ &dd_idx, &pd_idx, &qd_idx);
rcu_read_lock();
rdev = rcu_dereference(conf->disks[dd_idx].rdev);
@@ -3380,7 +3417,7 @@
{
mddev_t *mddev = q->queuedata;
raid5_conf_t *conf = mddev_to_conf(mddev);
- unsigned int dd_idx, pd_idx;
+ int dd_idx, pd_idx, qd_idx;
sector_t new_sector;
sector_t logical_sector, last_sector;
struct stripe_head *sh;
@@ -3447,7 +3484,7 @@
new_sector = raid5_compute_sector(conf, logical_sector,
previous,
- &dd_idx, &pd_idx);
+ &dd_idx, &pd_idx, &qd_idx);
pr_debug("raid5: make_request, sector %llu logical %llu\n",
(unsigned long long)new_sector,
(unsigned long long)logical_sector);
@@ -3535,7 +3572,7 @@
*/
raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
struct stripe_head *sh;
- int pd_idx;
+ int pd_idx, qd_idx;
sector_t first_sector, last_sector;
int raid_disks = conf->previous_raid_disks;
int data_disks = raid_disks - conf->max_degraded;
@@ -3598,7 +3635,7 @@
if (j == sh->pd_idx)
continue;
if (conf->level == 6 &&
- j == raid6_next_disk(sh->pd_idx, sh->disks))
+ j == sh->qd_idx)
continue;
s = compute_blocknr(sh, j);
if (s < mddev->array_sectors) {
@@ -3625,11 +3662,11 @@
*/
first_sector =
raid5_compute_sector(conf, sector_nr*(new_data_disks),
- 1, &dd_idx, &pd_idx);
+ 1, &dd_idx, &pd_idx, &qd_idx);
last_sector =
raid5_compute_sector(conf, ((sector_nr+conf->chunk_size/512)
*(new_data_disks) - 1),
- 1, &dd_idx, &pd_idx);
+ 1, &dd_idx, &pd_idx, &qd_idx);
if (last_sector >= mddev->dev_sectors)
last_sector = mddev->dev_sectors - 1;
while (first_sector <= last_sector) {
@@ -3764,7 +3801,7 @@
* it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
*/
struct stripe_head *sh;
- int dd_idx, pd_idx;
+ int dd_idx, pd_idx, qd_idx;
sector_t sector, logical_sector, last_sector;
int scnt = 0;
int remaining;
@@ -3772,7 +3809,7 @@
logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
sector = raid5_compute_sector(conf, logical_sector,
- 0, &dd_idx, &pd_idx);
+ 0, &dd_idx, &pd_idx, &qd_idx);
last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
for (; logical_sector < last_sector;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 0ed22df..0c7375a 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -196,15 +196,16 @@
struct stripe_head {
struct hlist_node hash;
- struct list_head lru; /* inactive_list or handle_list */
- struct raid5_private_data *raid_conf;
- sector_t sector; /* sector of this row */
- int pd_idx; /* parity disk index */
- unsigned long state; /* state flags */
- atomic_t count; /* nr of active thread/requests */
+ struct list_head lru; /* inactive_list or handle_list */
+ struct raid5_private_data *raid_conf;
+ sector_t sector; /* sector of this row */
+ short pd_idx; /* parity disk index */
+ short qd_idx; /* 'Q' disk index for raid6 */
+ unsigned long state; /* state flags */
+ atomic_t count; /* nr of active thread/requests */
spinlock_t lock;
int bm_seq; /* sequence number for bitmap flushes */
- int disks; /* disks in stripe */
+ int disks; /* disks in stripe */
enum check_states check_state;
enum reconstruct_states reconstruct_state;
/* stripe_operations
