md/raid10: handle merge_bvec_fn in member devices.
Currently we don't honour merge_bvec_fn in member devices so if there is one, we force all requests to be single-page at most. This is not ideal. So enhance the raid10 merge_bvec_fn to check that function in children as well. This introduces a small problem. There is no locking around calls the ->merge_bvec_fn and subsequent calls to ->make_request. So a device added between these could end up getting a request which violates its merge_bvec_fn. Currently the best we can do is synchronize_sched(). This will work providing no preemption happens. If there is preemption, we just have to hope that new devices are largely consistent with old devices. Signed-off-by: NeilBrown <neilb@suse.de>
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@ -5073,6 +5073,7 @@ static void md_clean(struct mddev *mddev)
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mddev->changed = 0;
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mddev->degraded = 0;
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mddev->safemode = 0;
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mddev->merge_check_needed = 0;
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mddev->bitmap_info.offset = 0;
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mddev->bitmap_info.default_offset = 0;
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mddev->bitmap_info.chunksize = 0;
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@ -128,6 +128,10 @@ struct md_rdev {
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enum flag_bits {
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Faulty, /* device is known to have a fault */
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In_sync, /* device is in_sync with rest of array */
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Unmerged, /* device is being added to array and should
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* be considerred for bvec_merge_fn but not
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* yet for actual IO
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*/
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WriteMostly, /* Avoid reading if at all possible */
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AutoDetected, /* added by auto-detect */
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Blocked, /* An error occurred but has not yet
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@ -345,6 +349,10 @@ struct mddev {
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int degraded; /* whether md should consider
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* adding a spare
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*/
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int merge_check_needed; /* at least one
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* member device
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* has a
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* merge_bvec_fn */
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atomic_t recovery_active; /* blocks scheduled, but not written */
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wait_queue_head_t recovery_wait;
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@ -586,24 +586,67 @@ static sector_t raid10_find_virt(struct r10conf *conf, sector_t sector, int dev)
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* @biovec: the request that could be merged to it.
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*
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* Return amount of bytes we can accept at this offset
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* If near_copies == raid_disk, there are no striping issues,
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* but in that case, the function isn't called at all.
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* This requires checking for end-of-chunk if near_copies != raid_disks,
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* and for subordinate merge_bvec_fns if merge_check_needed.
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*/
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static int raid10_mergeable_bvec(struct request_queue *q,
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struct bvec_merge_data *bvm,
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struct bio_vec *biovec)
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{
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struct mddev *mddev = q->queuedata;
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struct r10conf *conf = mddev->private;
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sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
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int max;
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unsigned int chunk_sectors = mddev->chunk_sectors;
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unsigned int bio_sectors = bvm->bi_size >> 9;
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max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
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if (max < 0) max = 0; /* bio_add cannot handle a negative return */
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if (conf->near_copies < conf->raid_disks) {
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max = (chunk_sectors - ((sector & (chunk_sectors - 1))
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+ bio_sectors)) << 9;
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if (max < 0)
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/* bio_add cannot handle a negative return */
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max = 0;
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if (max <= biovec->bv_len && bio_sectors == 0)
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return biovec->bv_len;
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else
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} else
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max = biovec->bv_len;
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if (mddev->merge_check_needed) {
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struct r10bio r10_bio;
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int s;
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r10_bio.sector = sector;
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raid10_find_phys(conf, &r10_bio);
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rcu_read_lock();
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for (s = 0; s < conf->copies; s++) {
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int disk = r10_bio.devs[s].devnum;
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struct md_rdev *rdev = rcu_dereference(
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conf->mirrors[disk].rdev);
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if (rdev && !test_bit(Faulty, &rdev->flags)) {
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struct request_queue *q =
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bdev_get_queue(rdev->bdev);
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if (q->merge_bvec_fn) {
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bvm->bi_sector = r10_bio.devs[s].addr
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+ rdev->data_offset;
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bvm->bi_bdev = rdev->bdev;
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max = min(max, q->merge_bvec_fn(
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q, bvm, biovec));
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}
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}
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rdev = rcu_dereference(conf->mirrors[disk].replacement);
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if (rdev && !test_bit(Faulty, &rdev->flags)) {
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struct request_queue *q =
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bdev_get_queue(rdev->bdev);
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if (q->merge_bvec_fn) {
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bvm->bi_sector = r10_bio.devs[s].addr
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+ rdev->data_offset;
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bvm->bi_bdev = rdev->bdev;
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max = min(max, q->merge_bvec_fn(
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q, bvm, biovec));
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}
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}
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}
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rcu_read_unlock();
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}
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return max;
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}
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@ -668,11 +711,12 @@ retry:
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disk = r10_bio->devs[slot].devnum;
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rdev = rcu_dereference(conf->mirrors[disk].replacement);
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if (rdev == NULL || test_bit(Faulty, &rdev->flags) ||
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test_bit(Unmerged, &rdev->flags) ||
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r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
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rdev = rcu_dereference(conf->mirrors[disk].rdev);
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if (rdev == NULL)
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continue;
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if (test_bit(Faulty, &rdev->flags))
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if (rdev == NULL ||
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test_bit(Faulty, &rdev->flags) ||
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test_bit(Unmerged, &rdev->flags))
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continue;
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if (!test_bit(In_sync, &rdev->flags) &&
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r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
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@ -1134,12 +1178,14 @@ retry_write:
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blocked_rdev = rrdev;
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break;
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}
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if (rrdev && test_bit(Faulty, &rrdev->flags))
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if (rrdev && (test_bit(Faulty, &rrdev->flags)
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|| test_bit(Unmerged, &rrdev->flags)))
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rrdev = NULL;
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r10_bio->devs[i].bio = NULL;
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r10_bio->devs[i].repl_bio = NULL;
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if (!rdev || test_bit(Faulty, &rdev->flags)) {
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if (!rdev || test_bit(Faulty, &rdev->flags) ||
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test_bit(Unmerged, &rdev->flags)) {
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set_bit(R10BIO_Degraded, &r10_bio->state);
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continue;
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}
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@ -1490,6 +1536,7 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
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int mirror;
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int first = 0;
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int last = conf->raid_disks - 1;
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struct request_queue *q = bdev_get_queue(rdev->bdev);
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if (mddev->recovery_cp < MaxSector)
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/* only hot-add to in-sync arrays, as recovery is
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@ -1502,6 +1549,11 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
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if (rdev->raid_disk >= 0)
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first = last = rdev->raid_disk;
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if (q->merge_bvec_fn) {
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set_bit(Unmerged, &rdev->flags);
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mddev->merge_check_needed = 1;
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}
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if (rdev->saved_raid_disk >= first &&
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conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
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mirror = rdev->saved_raid_disk;
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@ -1521,11 +1573,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
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err = 0;
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disk_stack_limits(mddev->gendisk, rdev->bdev,
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rdev->data_offset << 9);
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if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
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blk_queue_max_segments(mddev->queue, 1);
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blk_queue_segment_boundary(mddev->queue,
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PAGE_CACHE_SIZE - 1);
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}
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conf->fullsync = 1;
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rcu_assign_pointer(p->replacement, rdev);
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break;
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@ -1533,17 +1580,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
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disk_stack_limits(mddev->gendisk, rdev->bdev,
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rdev->data_offset << 9);
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/* as we don't honour merge_bvec_fn, we must
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* never risk violating it, so limit
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* ->max_segments to one lying with a single
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* page, as a one page request is never in
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* violation.
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*/
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if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
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blk_queue_max_segments(mddev->queue, 1);
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blk_queue_segment_boundary(mddev->queue,
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PAGE_CACHE_SIZE - 1);
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}
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p->head_position = 0;
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p->recovery_disabled = mddev->recovery_disabled - 1;
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@ -1554,7 +1590,19 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
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rcu_assign_pointer(p->rdev, rdev);
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break;
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}
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if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
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/* Some requests might not have seen this new
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* merge_bvec_fn. We must wait for them to complete
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* before merging the device fully.
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* First we make sure any code which has tested
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* our function has submitted the request, then
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* we wait for all outstanding requests to complete.
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*/
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synchronize_sched();
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raise_barrier(conf, 0);
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lower_barrier(conf);
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clear_bit(Unmerged, &rdev->flags);
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}
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md_integrity_add_rdev(rdev, mddev);
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print_conf(conf);
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return err;
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@ -2098,6 +2146,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
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d = r10_bio->devs[sl].devnum;
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rdev = rcu_dereference(conf->mirrors[d].rdev);
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if (rdev &&
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!test_bit(Unmerged, &rdev->flags) &&
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test_bit(In_sync, &rdev->flags) &&
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is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
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&first_bad, &bad_sectors) == 0) {
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@ -2151,6 +2200,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
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d = r10_bio->devs[sl].devnum;
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rdev = rcu_dereference(conf->mirrors[d].rdev);
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if (!rdev ||
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test_bit(Unmerged, &rdev->flags) ||
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!test_bit(In_sync, &rdev->flags))
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continue;
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@ -3273,15 +3323,6 @@ static int run(struct mddev *mddev)
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disk_stack_limits(mddev->gendisk, rdev->bdev,
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rdev->data_offset << 9);
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/* as we don't honour merge_bvec_fn, we must never risk
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* violating it, so limit max_segments to 1 lying
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* within a single page.
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*/
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if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
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blk_queue_max_segments(mddev->queue, 1);
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blk_queue_segment_boundary(mddev->queue,
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PAGE_CACHE_SIZE - 1);
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}
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disk->head_position = 0;
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}
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@ -3345,7 +3386,6 @@ static int run(struct mddev *mddev)
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mddev->queue->backing_dev_info.ra_pages = 2* stripe;
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}
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if (conf->near_copies < conf->raid_disks)
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blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
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if (md_integrity_register(mddev))
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