From ca65b73bd9c301d243df93780f7b26579e6c9204 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 6 Jan 2006 00:20:17 -0800 Subject: [PATCH] md: fix raid6 resync check/repair code raid6 currently does not check the P/Q syndromes when doing a resync, it just calculates the correct value and writes it. Doing the check can reduce writes (often to 0) for a resync, and it is needed to properly implement the echo check > sync_action operation. This patch implements the appropriate checks and tidies up some related code. It also allows raid6 user-requested resync to bypass the intent bitmap. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/raid6main.c | 182 ++++++++++++++++++++++++++++--------------------- 1 file changed, 106 insertions(+), 76 deletions(-) (limited to 'drivers/md/raid6main.c') diff --git a/drivers/md/raid6main.c b/drivers/md/raid6main.c index 304455d236f9..52e8796bb8ac 100644 --- a/drivers/md/raid6main.c +++ b/drivers/md/raid6main.c @@ -805,7 +805,7 @@ static void compute_parity(struct stripe_head *sh, int method) } /* Compute one missing block */ -static void compute_block_1(struct stripe_head *sh, int dd_idx) +static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero) { raid6_conf_t *conf = sh->raid_conf; int i, count, disks = conf->raid_disks; @@ -821,7 +821,7 @@ static void compute_block_1(struct stripe_head *sh, int dd_idx) compute_parity(sh, UPDATE_PARITY); } else { ptr[0] = page_address(sh->dev[dd_idx].page); - memset(ptr[0], 0, STRIPE_SIZE); + if (!nozero) memset(ptr[0], 0, STRIPE_SIZE); count = 1; for (i = disks ; i--; ) { if (i == dd_idx || i == qd_idx) @@ -838,7 +838,8 @@ static void compute_block_1(struct stripe_head *sh, int dd_idx) } if (count != 1) xor_block(count, STRIPE_SIZE, ptr); - set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags); + if (!nozero) set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags); + else clear_bit(R5_UPTODATE, &sh->dev[dd_idx].flags); } } @@ -871,7 +872,7 @@ 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); + compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1, 0); compute_parity(sh, UPDATE_PARITY); /* Is this necessary? */ return; } @@ -982,6 +983,12 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in } +static int page_is_zero(struct page *p) +{ + char *a = page_address(p); + return ((*(u32*)a) == 0 && + memcmp(a, a+4, STRIPE_SIZE-4)==0); +} /* * handle_stripe - do things to a stripe. * @@ -1000,7 +1007,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in * */ -static void handle_stripe(struct stripe_head *sh) +static void handle_stripe(struct stripe_head *sh, struct page *tmp_page) { raid6_conf_t *conf = sh->raid_conf; int disks = conf->raid_disks; @@ -1228,7 +1235,7 @@ static void handle_stripe(struct stripe_head *sh) if (uptodate == disks-1) { PRINTK("Computing stripe %llu block %d\n", (unsigned long long)sh->sector, i); - compute_block_1(sh, i); + compute_block_1(sh, i, 0); uptodate++; } else if ( uptodate == disks-2 && failed >= 2 ) { /* Computing 2-failure is *very* expensive; only do it if failed >= 2 */ @@ -1323,7 +1330,7 @@ static void handle_stripe(struct stripe_head *sh) /* We have failed blocks and need to compute them */ switch ( failed ) { case 0: BUG(); - case 1: compute_block_1(sh, failed_num[0]); break; + case 1: compute_block_1(sh, failed_num[0], 0); break; case 2: compute_block_2(sh, failed_num[0], failed_num[1]); break; default: BUG(); /* This request should have been failed? */ } @@ -1338,12 +1345,10 @@ static void handle_stripe(struct stripe_head *sh) (unsigned long long)sh->sector, i); locked++; set_bit(R5_Wantwrite, &sh->dev[i].flags); -#if 0 /**** FIX: I don't understand the logic here... ****/ - if (!test_bit(R5_Insync, &sh->dev[i].flags) - || ((i==pd_idx || i==qd_idx) && failed == 0)) /* FIX? */ - set_bit(STRIPE_INSYNC, &sh->state); -#endif } + /* after a RECONSTRUCT_WRITE, the stripe MUST be in-sync */ + set_bit(STRIPE_INSYNC, &sh->state); + if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) { atomic_dec(&conf->preread_active_stripes); if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) @@ -1356,79 +1361,97 @@ static void handle_stripe(struct stripe_head *sh) * Any reads will already have been scheduled, so we just see if enough data * is available */ - if (syncing && locked == 0 && - !test_bit(STRIPE_INSYNC, &sh->state) && failed <= 2) { - set_bit(STRIPE_HANDLE, &sh->state); -#if 0 /* RAID-6: Don't support CHECK PARITY yet */ - if (failed == 0) { - char *pagea; - if (uptodate != disks) - BUG(); - compute_parity(sh, CHECK_PARITY); - uptodate--; - pagea = page_address(sh->dev[pd_idx].page); - if ((*(u32*)pagea) == 0 && - !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) { - /* parity is correct (on disc, not in buffer any more) */ - set_bit(STRIPE_INSYNC, &sh->state); - } - } -#endif - if (!test_bit(STRIPE_INSYNC, &sh->state)) { - int failed_needupdate[2]; - struct r5dev *adev, *bdev; - - if ( failed < 1 ) - failed_num[0] = pd_idx; - if ( failed < 2 ) - failed_num[1] = (failed_num[0] == qd_idx) ? pd_idx : qd_idx; + if (syncing && locked == 0 && !test_bit(STRIPE_INSYNC, &sh->state)) { + int update_p = 0, update_q = 0; + struct r5dev *dev; - failed_needupdate[0] = !test_bit(R5_UPTODATE, &sh->dev[failed_num[0]].flags); - failed_needupdate[1] = !test_bit(R5_UPTODATE, &sh->dev[failed_num[1]].flags); + set_bit(STRIPE_HANDLE, &sh->state); - PRINTK("sync: failed=%d num=%d,%d fnu=%u%u\n", - failed, failed_num[0], failed_num[1], failed_needupdate[0], failed_needupdate[1]); + BUG_ON(failed>2); + BUG_ON(uptodate < disks); + /* Want to check and possibly repair P and Q. + * However there could be one 'failed' device, in which + * case we can only check one of them, possibly using the + * other to generate missing data + */ -#if 0 /* RAID-6: This code seems to require that CHECK_PARITY destroys the uptodateness of the parity */ - /* should be able to compute the missing block(s) and write to spare */ - if ( failed_needupdate[0] ^ failed_needupdate[1] ) { - if (uptodate+1 != disks) - BUG(); - compute_block_1(sh, failed_needupdate[0] ? failed_num[0] : failed_num[1]); - uptodate++; - } else if ( failed_needupdate[0] & failed_needupdate[1] ) { - if (uptodate+2 != disks) - BUG(); - compute_block_2(sh, failed_num[0], failed_num[1]); - uptodate += 2; + /* If !tmp_page, we cannot do the calculations, + * but as we have set STRIPE_HANDLE, we will soon be called + * by stripe_handle with a tmp_page - just wait until then. + */ + if (tmp_page) { + if (failed == q_failed) { + /* The only possible failed device holds 'Q', so it makes + * sense to check P (If anything else were failed, we would + * have used P to recreate it). + */ + compute_block_1(sh, pd_idx, 1); + if (!page_is_zero(sh->dev[pd_idx].page)) { + compute_block_1(sh,pd_idx,0); + update_p = 1; + } + } + if (!q_failed && failed < 2) { + /* q is not failed, and we didn't use it to generate + * anything, so it makes sense to check it + */ + memcpy(page_address(tmp_page), + page_address(sh->dev[qd_idx].page), + STRIPE_SIZE); + compute_parity(sh, UPDATE_PARITY); + if (memcmp(page_address(tmp_page), + page_address(sh->dev[qd_idx].page), + STRIPE_SIZE)!= 0) { + clear_bit(STRIPE_INSYNC, &sh->state); + update_q = 1; + } + } + if (update_p || update_q) { + conf->mddev->resync_mismatches += STRIPE_SECTORS; + if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery)) + /* don't try to repair!! */ + update_p = update_q = 0; } -#else - compute_block_2(sh, failed_num[0], failed_num[1]); - uptodate += failed_needupdate[0] + failed_needupdate[1]; -#endif - if (uptodate != disks) - BUG(); + /* now write out any block on a failed drive, + * or P or Q if they need it + */ - PRINTK("Marking for sync stripe %llu blocks %d,%d\n", - (unsigned long long)sh->sector, failed_num[0], failed_num[1]); + if (failed == 2) { + dev = &sh->dev[failed_num[1]]; + locked++; + set_bit(R5_LOCKED, &dev->flags); + set_bit(R5_Wantwrite, &dev->flags); + set_bit(R5_Syncio, &dev->flags); + } + if (failed >= 1) { + dev = &sh->dev[failed_num[0]]; + locked++; + set_bit(R5_LOCKED, &dev->flags); + set_bit(R5_Wantwrite, &dev->flags); + set_bit(R5_Syncio, &dev->flags); + } - /**** FIX: Should we really do both of these unconditionally? ****/ - adev = &sh->dev[failed_num[0]]; - locked += !test_bit(R5_LOCKED, &adev->flags); - set_bit(R5_LOCKED, &adev->flags); - set_bit(R5_Wantwrite, &adev->flags); - bdev = &sh->dev[failed_num[1]]; - locked += !test_bit(R5_LOCKED, &bdev->flags); - set_bit(R5_LOCKED, &bdev->flags); + if (update_p) { + dev = &sh->dev[pd_idx]; + locked ++; + set_bit(R5_LOCKED, &dev->flags); + set_bit(R5_Wantwrite, &dev->flags); + set_bit(R5_Syncio, &dev->flags); + } + if (update_q) { + dev = &sh->dev[qd_idx]; + locked++; + set_bit(R5_LOCKED, &dev->flags); + set_bit(R5_Wantwrite, &dev->flags); + set_bit(R5_Syncio, &dev->flags); + } clear_bit(STRIPE_DEGRADED, &sh->state); - set_bit(R5_Wantwrite, &bdev->flags); set_bit(STRIPE_INSYNC, &sh->state); - set_bit(R5_Syncio, &adev->flags); - set_bit(R5_Syncio, &bdev->flags); } } + if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) { md_done_sync(conf->mddev, STRIPE_SECTORS,1); clear_bit(STRIPE_SYNCING, &sh->state); @@ -1664,7 +1687,7 @@ static int make_request (request_queue_t *q, struct bio * bi) } finish_wait(&conf->wait_for_overlap, &w); raid6_plug_device(conf); - handle_stripe(sh); + handle_stripe(sh, NULL); release_stripe(sh); } else { /* cannot get stripe for read-ahead, just give-up */ @@ -1728,6 +1751,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i return rv; } if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) && + !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) && !conf->fullsync && sync_blocks >= STRIPE_SECTORS) { /* we can skip this block, and probably more */ sync_blocks /= STRIPE_SECTORS; @@ -1765,7 +1789,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i clear_bit(STRIPE_INSYNC, &sh->state); spin_unlock(&sh->lock); - handle_stripe(sh); + handle_stripe(sh, NULL); release_stripe(sh); return STRIPE_SECTORS; @@ -1821,7 +1845,7 @@ static void raid6d (mddev_t *mddev) spin_unlock_irq(&conf->device_lock); handled++; - handle_stripe(sh); + handle_stripe(sh, conf->spare_page); release_stripe(sh); spin_lock_irq(&conf->device_lock); @@ -1860,6 +1884,10 @@ static int run(mddev_t *mddev) goto abort; memset(conf->stripe_hashtbl, 0, HASH_PAGES * PAGE_SIZE); + conf->spare_page = alloc_page(GFP_KERNEL); + if (!conf->spare_page) + goto abort; + spin_lock_init(&conf->device_lock); init_waitqueue_head(&conf->wait_for_stripe); init_waitqueue_head(&conf->wait_for_overlap); @@ -1996,6 +2024,8 @@ static int run(mddev_t *mddev) abort: if (conf) { print_raid6_conf(conf); + if (conf->spare_page) + page_cache_release(conf->spare_page); if (conf->stripe_hashtbl) free_pages((unsigned long) conf->stripe_hashtbl, HASH_PAGES_ORDER); -- cgit v1.2.3