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Commit 1877db75 authored by NeilBrown's avatar NeilBrown
Browse files

md/raid1: restore ability for check and repair to fix read errors. 



commit 30bc9b53
    md/raid1: fix bio handling problems in process_checks()

Move the bio_reset() to a point before where BIO_UPTODATE is checked,
so that check now always report that the bio is uptodate, even if it is not.

This causes process_check() to sometimes treat read-errors as
successful matches so the good data isn't written out.

This patch preserves the flag until it is needed.

Bug was introduced in 3.11, but backported to 3.10-stable (as it fixed
an even worse bug).  So suitable for any -stable since 3.10.

Reported-and-tested-by: default avatarMichael Tokarev <mjt@tls.msk.ru>
Cc: stable@vger.kernel.org (3.10+)
Fixed: 30bc9b53
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 38dbfb59

drivers/md/raid1.c

+10 −3
Original line number Diff line number Diff line
@@ -1953,11 +1953,15 @@ static int process_checks(struct r1bio *r1_bio) 
	for (i = 0; i < conf->raid_disks * 2; i++) {

		int j;

		int size;

		int uptodate;

		struct bio *b = r1_bio->bios[i];

		if (b->bi_end_io != end_sync_read)

			continue;

		/* fixup the bio for reuse */

		/* fixup the bio for reuse, but preserve BIO_UPTODATE */

		uptodate = test_bit(BIO_UPTODATE, &b->bi_flags);

		bio_reset(b);

		if (!uptodate)

			clear_bit(BIO_UPTODATE, &b->bi_flags);

		b->bi_vcnt = vcnt;

		b->bi_iter.bi_size = r1_bio->sectors << 9;

		b->bi_iter.bi_sector = r1_bio->sector +
@@ -1990,11 +1994,14 @@ static int process_checks(struct r1bio *r1_bio) 
		int j;

		struct bio *pbio = r1_bio->bios[primary];

		struct bio *sbio = r1_bio->bios[i];

		int uptodate = test_bit(BIO_UPTODATE, &sbio->bi_flags);



		if (sbio->bi_end_io != end_sync_read)

			continue;

		/* Now we can 'fixup' the BIO_UPTODATE flag */

		set_bit(BIO_UPTODATE, &sbio->bi_flags);



		if (test_bit(BIO_UPTODATE, &sbio->bi_flags)) {

		if (uptodate) {

			for (j = vcnt; j-- ; ) {

				struct page *p, *s;

				p = pbio->bi_io_vec[j].bv_page;
@@ -2009,7 +2016,7 @@ static int process_checks(struct r1bio *r1_bio) 
		if (j >= 0)

			atomic64_add(r1_bio->sectors, &mddev->resync_mismatches);

		if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)

			      && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {

			      && uptodate)) {

			/* No need to write to this device. */

			sbio->bi_end_io = NULL;

			rdev_dec_pending(conf->mirrors[i].rdev, mddev);