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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>
This commit is contained in:
NeilBrown 2009-03-31 14:39:38 +11:00
parent 112bf8970d
commit d0dabf7e57
2 changed files with 132 additions and 94 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

211
drivers/md/raid5.c
View File

@ -133,12 +133,36 @@ static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
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(raid5_conf_t *conf, struct stripe_head *sh)
}
}
}
static void release_stripe(struct stripe_head *sh)
{
raid5_conf_t *conf = sh->raid_conf;
@ -274,12 +299,14 @@ static int grow_buffers(struct stripe_head *sh, int num)
}
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 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
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 void error(mddev_t *mddev, mdk_rdev_t *rdev)
*/
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 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
/*
* 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 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
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 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
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 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
}
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 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
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 copy_data(int frombio, struct bio *bio,
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 @@ static void compute_parity6(struct stripe_head *sh, int method)
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 @@ static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
{
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_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 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 @@ static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
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 @@ static int page_is_zero(struct page *p)
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 @@ static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int previous)
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 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
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 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
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 @@ static bool handle_stripe5(struct stripe_head *sh)
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 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
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 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
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 @@ static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
{
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 @@ static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
*/
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 @@ static int make_request(struct request_queue *q, struct bio * bi)
{
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 @@ static int make_request(struct request_queue *q, struct bio * bi)
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 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
*/
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 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
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 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
*/
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 @@ static int retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
* 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 @@ static int retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
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;

15
drivers/md/raid5.h
View File

@ -196,15 +196,16 @@ enum reconstruct_states {
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