From 0eb3ff12aa8a12538ef681dc83f4361636a0699f Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 6 Jan 2006 00:20:29 -0800 Subject: [PATCH] md: raid10 read-error handling - resync and read-only Add in correct read-error handling for resync and read-only situations. When read-only, we don't over-write, so we need to mark the failed drive in the r10_bio so we don't re-try it. During resync, we always read all blocks, so if there is a read error, we simply over-write it with the good block that we found (assuming we found one). Note that the recovery case still isn't handled in an interesting way. There is nothing useful to do for the 2-copies case. If there are 3 or more copies, then we could try reading from one of the non-missing copies, but this is a bit complicated and very rarely would be used, so I'm leaving it for now. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/raid10.c | 56 ++++++++++++++++++++++++++++----------------- include/linux/raid/raid10.h | 7 ++++++ 2 files changed, 42 insertions(+), 21 deletions(-) diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 64bb4ddc679..3f8df2ecbae 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -172,7 +172,7 @@ static void put_all_bios(conf_t *conf, r10bio_t *r10_bio) for (i = 0; i < conf->copies; i++) { struct bio **bio = & r10_bio->devs[i].bio; - if (*bio) + if (*bio && *bio != IO_BLOCKED) bio_put(*bio); *bio = NULL; } @@ -500,6 +500,7 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio) disk = r10_bio->devs[slot].devnum; while ((rdev = rcu_dereference(conf->mirrors[disk].rdev)) == NULL || + r10_bio->devs[slot].bio == IO_BLOCKED || !test_bit(In_sync, &rdev->flags)) { slot++; if (slot == conf->copies) { @@ -517,6 +518,7 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio) slot = 0; disk = r10_bio->devs[slot].devnum; while ((rdev=rcu_dereference(conf->mirrors[disk].rdev)) == NULL || + r10_bio->devs[slot].bio == IO_BLOCKED || !test_bit(In_sync, &rdev->flags)) { slot ++; if (slot == conf->copies) { @@ -537,6 +539,7 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio) if ((rdev=rcu_dereference(conf->mirrors[ndisk].rdev)) == NULL || + r10_bio->devs[nslot].bio == IO_BLOCKED || !test_bit(In_sync, &rdev->flags)) continue; @@ -1104,7 +1107,6 @@ abort: static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error) { - int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private); conf_t *conf = mddev_to_conf(r10_bio->mddev); int i,d; @@ -1119,7 +1121,10 @@ static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error) BUG(); update_head_pos(i, r10_bio); d = r10_bio->devs[i].devnum; - if (!uptodate) + + if (test_bit(BIO_UPTODATE, &bio->bi_flags)) + set_bit(R10BIO_Uptodate, &r10_bio->state); + else if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery)) md_error(r10_bio->mddev, conf->mirrors[d].rdev); @@ -1209,25 +1214,30 @@ static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio) fbio = r10_bio->devs[i].bio; /* now find blocks with errors */ - for (i=first+1 ; i < conf->copies ; i++) { - int vcnt, j, d; + for (i=0 ; i < conf->copies ; i++) { + int j, d; + int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9); - if (!test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) - continue; - /* We know that the bi_io_vec layout is the same for - * both 'first' and 'i', so we just compare them. - * All vec entries are PAGE_SIZE; - */ tbio = r10_bio->devs[i].bio; - vcnt = r10_bio->sectors >> (PAGE_SHIFT-9); - for (j = 0; j < vcnt; j++) - if (memcmp(page_address(fbio->bi_io_vec[j].bv_page), - page_address(tbio->bi_io_vec[j].bv_page), - PAGE_SIZE)) - break; - if (j == vcnt) + + if (tbio->bi_end_io != end_sync_read) + continue; + if (i == first) continue; - mddev->resync_mismatches += r10_bio->sectors; + if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) { + /* We know that the bi_io_vec layout is the same for + * both 'first' and 'i', so we just compare them. + * All vec entries are PAGE_SIZE; + */ + for (j = 0; j < vcnt; j++) + if (memcmp(page_address(fbio->bi_io_vec[j].bv_page), + page_address(tbio->bi_io_vec[j].bv_page), + PAGE_SIZE)) + break; + if (j == vcnt) + continue; + mddev->resync_mismatches += r10_bio->sectors; + } if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) /* Don't fix anything. */ continue; @@ -1308,7 +1318,10 @@ static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio) atomic_inc(&conf->mirrors[d].rdev->nr_pending); md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9); - generic_make_request(wbio); + if (test_bit(R10BIO_Uptodate, &r10_bio->state)) + generic_make_request(wbio); + else + bio_endio(wbio, wbio->bi_size, -EIO); } @@ -1445,7 +1458,8 @@ static void raid10d(mddev_t *mddev) unfreeze_array(conf); bio = r10_bio->devs[r10_bio->read_slot].bio; - r10_bio->devs[r10_bio->read_slot].bio = NULL; + r10_bio->devs[r10_bio->read_slot].bio = + mddev->ro ? IO_BLOCKED : NULL; bio_put(bio); mirror = read_balance(conf, r10_bio); if (mirror == -1) { diff --git a/include/linux/raid/raid10.h b/include/linux/raid/raid10.h index dfa528385e3..b1103298a8c 100644 --- a/include/linux/raid/raid10.h +++ b/include/linux/raid/raid10.h @@ -104,6 +104,13 @@ struct r10bio_s { } devs[0]; }; +/* when we get a read error on a read-only array, we redirect to another + * device without failing the first device, or trying to over-write to + * correct the read error. To keep track of bad blocks on a per-bio + * level, we store IO_BLOCKED in the appropriate 'bios' pointer + */ +#define IO_BLOCKED ((struct bio*)1) + /* bits for r10bio.state */ #define R10BIO_Uptodate 0 #define R10BIO_IsSync 1 -- cgit v1.2.3