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: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
NeilBrown
Shaohua Li
parent
212e7eb7a3
commit
8d3ca83dcf
@ -719,6 +719,7 @@ static struct md_rdev *read_balance(struct r10conf *conf,
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best_dist = MaxSector;
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best_good_sectors = 0;
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do_balance = 1;
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clear_bit(R10BIO_FailFast, &r10_bio->state);
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/*
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* Check if we can balance. We can balance on the whole
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* device if no resync is going on (recovery is ok), or below
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@ -783,15 +784,18 @@ static struct md_rdev *read_balance(struct r10conf *conf,
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if (!do_balance)
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break;
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if (best_slot >= 0)
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/* At least 2 disks to choose from so failfast is OK */
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set_bit(R10BIO_FailFast, &r10_bio->state);
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/* This optimisation is debatable, and completely destroys
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* sequential read speed for 'far copies' arrays. So only
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* keep it for 'near' arrays, and review those later.
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*/
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if (geo->near_copies > 1 && !atomic_read(&rdev->nr_pending))
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break;
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new_distance = 0;
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/* for far > 1 always use the lowest address */
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if (geo->far_copies > 1)
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else if (geo->far_copies > 1)
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new_distance = r10_bio->devs[slot].addr;
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else
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new_distance = abs(r10_bio->devs[slot].addr -
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@ -1170,6 +1174,9 @@ read_again:
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read_bio->bi_bdev = rdev->bdev;
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read_bio->bi_end_io = raid10_end_read_request;
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bio_set_op_attrs(read_bio, op, do_sync);
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if (test_bit(FailFast, &rdev->flags) &&
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test_bit(R10BIO_FailFast, &r10_bio->state))
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read_bio->bi_opf |= MD_FAILFAST;
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read_bio->bi_private = r10_bio;
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if (mddev->gendisk)
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@ -1988,6 +1995,7 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
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/* now find blocks with errors */
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for (i=0 ; i < conf->copies ; i++) {
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int j, d;
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struct md_rdev *rdev;
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tbio = r10_bio->devs[i].bio;
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@ -1995,6 +2003,8 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
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continue;
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if (i == first)
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continue;
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d = r10_bio->devs[i].devnum;
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rdev = conf->mirrors[d].rdev;
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if (!r10_bio->devs[i].bio->bi_error) {
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/* We know that the bi_io_vec layout is the same for
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* both 'first' and 'i', so we just compare them.
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@ -2017,6 +2027,10 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
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if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
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/* Don't fix anything. */
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continue;
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} else if (test_bit(FailFast, &rdev->flags)) {
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/* Just give up on this device */
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md_error(rdev->mddev, rdev);
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continue;
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}
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/* Ok, we need to write this bio, either to correct an
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* inconsistency or to correct an unreadable block.
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@ -2034,7 +2048,6 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
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bio_copy_data(tbio, fbio);
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d = r10_bio->devs[i].devnum;
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atomic_inc(&conf->mirrors[d].rdev->nr_pending);
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atomic_inc(&r10_bio->remaining);
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md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(tbio));
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@ -2541,12 +2554,14 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
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bio_put(bio);
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r10_bio->devs[slot].bio = NULL;
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if (mddev->ro == 0) {
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if (mddev->ro)
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r10_bio->devs[slot].bio = IO_BLOCKED;
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else if (!test_bit(FailFast, &rdev->flags)) {
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freeze_array(conf, 1);
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fix_read_error(conf, mddev, r10_bio);
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unfreeze_array(conf);
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} else
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r10_bio->devs[slot].bio = IO_BLOCKED;
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md_error(mddev, rdev);
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rdev_dec_pending(rdev, mddev);
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@ -2575,6 +2590,9 @@ read_more:
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+ choose_data_offset(r10_bio, rdev);
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bio->bi_bdev = rdev->bdev;
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bio_set_op_attrs(bio, REQ_OP_READ, do_sync);
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if (test_bit(FailFast, &rdev->flags) &&
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test_bit(R10BIO_FailFast, &r10_bio->state))
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bio->bi_opf |= MD_FAILFAST;
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bio->bi_private = r10_bio;
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bio->bi_end_io = raid10_end_read_request;
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trace_block_bio_remap(bdev_get_queue(bio->bi_bdev),
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@ -3096,6 +3114,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
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bio->bi_private = r10_bio;
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bio->bi_end_io = end_sync_read;
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bio_set_op_attrs(bio, REQ_OP_READ, 0);
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if (test_bit(FailFast, &rdev->flags))
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bio->bi_opf |= MD_FAILFAST;
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from_addr = r10_bio->devs[j].addr;
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bio->bi_iter.bi_sector = from_addr +
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rdev->data_offset;
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@ -3201,6 +3221,23 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
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rdev_dec_pending(mrdev, mddev);
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if (mreplace)
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rdev_dec_pending(mreplace, mddev);
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if (r10_bio->devs[0].bio->bi_opf & MD_FAILFAST) {
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/* Only want this if there is elsewhere to
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* read from. 'j' is currently the first
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* readable copy.
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*/
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int targets = 1;
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for (; j < conf->copies; j++) {
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int d = r10_bio->devs[j].devnum;
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if (conf->mirrors[d].rdev &&
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test_bit(In_sync,
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&conf->mirrors[d].rdev->flags))
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targets++;
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}
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if (targets == 1)
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r10_bio->devs[0].bio->bi_opf
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&= ~MD_FAILFAST;
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}
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}
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if (biolist == NULL) {
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while (r10_bio) {
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@ -3279,6 +3316,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
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bio->bi_private = r10_bio;
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bio->bi_end_io = end_sync_read;
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bio_set_op_attrs(bio, REQ_OP_READ, 0);
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if (test_bit(FailFast, &conf->mirrors[d].rdev->flags))
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bio->bi_opf |= MD_FAILFAST;
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bio->bi_iter.bi_sector = sector + rdev->data_offset;
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bio->bi_bdev = rdev->bdev;
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count++;
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@ -156,5 +156,7 @@ enum r10bio_state {
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* flag is set
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*/
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R10BIO_Previous,
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/* failfast devices did receive failfast requests. */
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R10BIO_FailFast,
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};
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#endif
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