From d0dabf7e577411c2bf6b616c751544dc241213d4 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 31 Mar 2009 14:39:38 +1100 Subject: [PATCH] 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 --- drivers/md/raid5.c | 211 ++++++++++++++++++++++++++------------------- drivers/md/raid5.h | 15 ++-- 2 files changed, 132 insertions(+), 94 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index c33073fe7426..cb3e157b52d3 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -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; diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index 0ed22dff56e0..0c7375ad12bd 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -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