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Commit 8d3ca83d authored by NeilBrown's avatar NeilBrown Committed by Shaohua Li
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md/raid10: add failfast handling for reads.



If a device is marked FailFast, and it is not the only
device we can read from, we mark the bio as MD_FAILFAST.

If this does fail-fast, we don't try read repair but just
allow failure.

If it was the last device, it doesn't get marked Faulty so
the retry happens on the same device - this time without
FAILFAST.  A subsequent failure will not retry but will just
pass up the error.

During resync we may use FAILFAST requests, and on a failure
we will simply use the other device(s).

During recovery we will only use FAILFAST in the unusual
case were there are multiple places to read from - i.e. if
there are > 2 devices.  If we get a failure we will fail the
device and complete the resync/recovery with remaining
devices.

Signed-off-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 212e7eb7
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+44 −5
Original line number Original line Diff line number Diff line
@@ -719,6 +719,7 @@ static struct md_rdev *read_balance(struct r10conf *conf,
	best_dist = MaxSector;
	best_dist = MaxSector;
	best_good_sectors = 0;
	best_good_sectors = 0;
	do_balance = 1;
	do_balance = 1;
	clear_bit(R10BIO_FailFast, &r10_bio->state);
	/*
	/*
	 * Check if we can balance. We can balance on the whole
	 * Check if we can balance. We can balance on the whole
	 * device if no resync is going on (recovery is ok), or below
	 * device if no resync is going on (recovery is ok), or below
@@ -783,15 +784,18 @@ static struct md_rdev *read_balance(struct r10conf *conf,
		if (!do_balance)
		if (!do_balance)
			break;
			break;


		if (best_slot >= 0)
			/* At least 2 disks to choose from so failfast is OK */
			set_bit(R10BIO_FailFast, &r10_bio->state);
		/* This optimisation is debatable, and completely destroys
		/* This optimisation is debatable, and completely destroys
		 * sequential read speed for 'far copies' arrays.  So only
		 * sequential read speed for 'far copies' arrays.  So only
		 * keep it for 'near' arrays, and review those later.
		 * keep it for 'near' arrays, and review those later.
		 */
		 */
		if (geo->near_copies > 1 && !atomic_read(&rdev->nr_pending))
		if (geo->near_copies > 1 && !atomic_read(&rdev->nr_pending))
			break;
			new_distance = 0;


		/* for far > 1 always use the lowest address */
		/* for far > 1 always use the lowest address */
		if (geo->far_copies > 1)
		else if (geo->far_copies > 1)
			new_distance = r10_bio->devs[slot].addr;
			new_distance = r10_bio->devs[slot].addr;
		else
		else
			new_distance = abs(r10_bio->devs[slot].addr -
			new_distance = abs(r10_bio->devs[slot].addr -
@@ -1170,6 +1174,9 @@ static void __make_request(struct mddev *mddev, struct bio *bio)
		read_bio->bi_bdev = rdev->bdev;
		read_bio->bi_bdev = rdev->bdev;
		read_bio->bi_end_io = raid10_end_read_request;
		read_bio->bi_end_io = raid10_end_read_request;
		bio_set_op_attrs(read_bio, op, do_sync);
		bio_set_op_attrs(read_bio, op, do_sync);
		if (test_bit(FailFast, &rdev->flags) &&
		    test_bit(R10BIO_FailFast, &r10_bio->state))
			read_bio->bi_opf |= MD_FAILFAST;
		read_bio->bi_private = r10_bio;
		read_bio->bi_private = r10_bio;


		if (mddev->gendisk)
		if (mddev->gendisk)
@@ -1988,6 +1995,7 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
	/* now find blocks with errors */
	/* now find blocks with errors */
	for (i=0 ; i < conf->copies ; i++) {
	for (i=0 ; i < conf->copies ; i++) {
		int  j, d;
		int  j, d;
		struct md_rdev *rdev;


		tbio = r10_bio->devs[i].bio;
		tbio = r10_bio->devs[i].bio;


@@ -1995,6 +2003,8 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
			continue;
			continue;
		if (i == first)
		if (i == first)
			continue;
			continue;
		d = r10_bio->devs[i].devnum;
		rdev = conf->mirrors[d].rdev;
		if (!r10_bio->devs[i].bio->bi_error) {
		if (!r10_bio->devs[i].bio->bi_error) {
			/* We know that the bi_io_vec layout is the same for
			/* We know that the bi_io_vec layout is the same for
			 * both 'first' and 'i', so we just compare them.
			 * both 'first' and 'i', so we just compare them.
@@ -2017,6 +2027,10 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
			if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
			if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
				/* Don't fix anything. */
				/* Don't fix anything. */
				continue;
				continue;
		} else if (test_bit(FailFast, &rdev->flags)) {
			/* Just give up on this device */
			md_error(rdev->mddev, rdev);
			continue;
		}
		}
		/* Ok, we need to write this bio, either to correct an
		/* Ok, we need to write this bio, either to correct an
		 * inconsistency or to correct an unreadable block.
		 * inconsistency or to correct an unreadable block.
@@ -2034,7 +2048,6 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)


		bio_copy_data(tbio, fbio);
		bio_copy_data(tbio, fbio);


		d = r10_bio->devs[i].devnum;
		atomic_inc(&conf->mirrors[d].rdev->nr_pending);
		atomic_inc(&conf->mirrors[d].rdev->nr_pending);
		atomic_inc(&r10_bio->remaining);
		atomic_inc(&r10_bio->remaining);
		md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(tbio));
		md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(tbio));
@@ -2541,12 +2554,14 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
	bio_put(bio);
	bio_put(bio);
	r10_bio->devs[slot].bio = NULL;
	r10_bio->devs[slot].bio = NULL;


	if (mddev->ro == 0) {
	if (mddev->ro)
		r10_bio->devs[slot].bio = IO_BLOCKED;
	else if (!test_bit(FailFast, &rdev->flags)) {
		freeze_array(conf, 1);
		freeze_array(conf, 1);
		fix_read_error(conf, mddev, r10_bio);
		fix_read_error(conf, mddev, r10_bio);
		unfreeze_array(conf);
		unfreeze_array(conf);
	} else
	} else
		r10_bio->devs[slot].bio = IO_BLOCKED;
		md_error(mddev, rdev);


	rdev_dec_pending(rdev, mddev);
	rdev_dec_pending(rdev, mddev);


@@ -2575,6 +2590,9 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
		+ choose_data_offset(r10_bio, rdev);
		+ choose_data_offset(r10_bio, rdev);
	bio->bi_bdev = rdev->bdev;
	bio->bi_bdev = rdev->bdev;
	bio_set_op_attrs(bio, REQ_OP_READ, do_sync);
	bio_set_op_attrs(bio, REQ_OP_READ, do_sync);
	if (test_bit(FailFast, &rdev->flags) &&
	    test_bit(R10BIO_FailFast, &r10_bio->state))
		bio->bi_opf |= MD_FAILFAST;
	bio->bi_private = r10_bio;
	bio->bi_private = r10_bio;
	bio->bi_end_io = raid10_end_read_request;
	bio->bi_end_io = raid10_end_read_request;
	trace_block_bio_remap(bdev_get_queue(bio->bi_bdev),
	trace_block_bio_remap(bdev_get_queue(bio->bi_bdev),
@@ -3096,6 +3114,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
				bio->bi_private = r10_bio;
				bio->bi_private = r10_bio;
				bio->bi_end_io = end_sync_read;
				bio->bi_end_io = end_sync_read;
				bio_set_op_attrs(bio, REQ_OP_READ, 0);
				bio_set_op_attrs(bio, REQ_OP_READ, 0);
				if (test_bit(FailFast, &rdev->flags))
					bio->bi_opf |= MD_FAILFAST;
				from_addr = r10_bio->devs[j].addr;
				from_addr = r10_bio->devs[j].addr;
				bio->bi_iter.bi_sector = from_addr +
				bio->bi_iter.bi_sector = from_addr +
					rdev->data_offset;
					rdev->data_offset;
@@ -3201,6 +3221,23 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
			rdev_dec_pending(mrdev, mddev);
			rdev_dec_pending(mrdev, mddev);
			if (mreplace)
			if (mreplace)
				rdev_dec_pending(mreplace, mddev);
				rdev_dec_pending(mreplace, mddev);
			if (r10_bio->devs[0].bio->bi_opf & MD_FAILFAST) {
				/* Only want this if there is elsewhere to
				 * read from. 'j' is currently the first
				 * readable copy.
				 */
				int targets = 1;
				for (; j < conf->copies; j++) {
					int d = r10_bio->devs[j].devnum;
					if (conf->mirrors[d].rdev &&
					    test_bit(In_sync,
						      &conf->mirrors[d].rdev->flags))
						targets++;
				}
				if (targets == 1)
					r10_bio->devs[0].bio->bi_opf
						&= ~MD_FAILFAST;
			}
		}
		}
		if (biolist == NULL) {
		if (biolist == NULL) {
			while (r10_bio) {
			while (r10_bio) {
@@ -3279,6 +3316,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
			bio->bi_private = r10_bio;
			bio->bi_private = r10_bio;
			bio->bi_end_io = end_sync_read;
			bio->bi_end_io = end_sync_read;
			bio_set_op_attrs(bio, REQ_OP_READ, 0);
			bio_set_op_attrs(bio, REQ_OP_READ, 0);
			if (test_bit(FailFast, &conf->mirrors[d].rdev->flags))
				bio->bi_opf |= MD_FAILFAST;
			bio->bi_iter.bi_sector = sector + rdev->data_offset;
			bio->bi_iter.bi_sector = sector + rdev->data_offset;
			bio->bi_bdev = rdev->bdev;
			bio->bi_bdev = rdev->bdev;
			count++;
			count++;
+2 −0
Original line number Original line Diff line number Diff line
@@ -156,5 +156,7 @@ enum r10bio_state {
 * flag is set
 * flag is set
 */
 */
	R10BIO_Previous,
	R10BIO_Previous,
/* failfast devices did receive failfast requests. */
	R10BIO_FailFast,
};
};
#endif
#endif