From 050b66152f87c79e8d66aed0e7996f9336462d5f Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 19 Mar 2012 12:46:39 +1100 Subject: [PATCH] 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 --- drivers/md/md.c | 1 + drivers/md/md.h | 8 +++ drivers/md/raid10.c | 122 +++++++++++++++++++++++++++++--------------- 3 files changed, 90 insertions(+), 41 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 119de175bf12..4566b61373d5 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -5073,6 +5073,7 @@ static void md_clean(struct mddev *mddev) mddev->changed = 0; mddev->degraded = 0; mddev->safemode = 0; + mddev->merge_check_needed = 0; mddev->bitmap_info.offset = 0; mddev->bitmap_info.default_offset = 0; mddev->bitmap_info.chunksize = 0; diff --git a/drivers/md/md.h b/drivers/md/md.h index 39acfe90cc26..1c2063ccf48e 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -128,6 +128,10 @@ struct md_rdev { enum flag_bits { Faulty, /* device is known to have a fault */ In_sync, /* device is in_sync with rest of array */ + Unmerged, /* device is being added to array and should + * be considerred for bvec_merge_fn but not + * yet for actual IO + */ WriteMostly, /* Avoid reading if at all possible */ AutoDetected, /* added by auto-detect */ Blocked, /* An error occurred but has not yet @@ -345,6 +349,10 @@ struct mddev { int degraded; /* whether md should consider * adding a spare */ + int merge_check_needed; /* at least one + * member device + * has a + * merge_bvec_fn */ atomic_t recovery_active; /* blocks scheduled, but not written */ wait_queue_head_t recovery_wait; diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 52bb37d4026d..e4a66ab6b0fb 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -586,25 +586,68 @@ static sector_t raid10_find_virt(struct r10conf *conf, sector_t sector, int dev) * @biovec: the request that could be merged to it. * * Return amount of bytes we can accept at this offset - * If near_copies == raid_disk, there are no striping issues, - * but in that case, the function isn't called at all. + * This requires checking for end-of-chunk if near_copies != raid_disks, + * and for subordinate merge_bvec_fns if merge_check_needed. */ static int raid10_mergeable_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *biovec) { struct mddev *mddev = q->queuedata; + struct r10conf *conf = mddev->private; sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev); int max; unsigned int chunk_sectors = mddev->chunk_sectors; unsigned int bio_sectors = bvm->bi_size >> 9; - max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9; - if (max < 0) max = 0; /* bio_add cannot handle a negative return */ - if (max <= biovec->bv_len && bio_sectors == 0) - return biovec->bv_len; - else - return max; + if (conf->near_copies < conf->raid_disks) { + max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + + bio_sectors)) << 9; + if (max < 0) + /* bio_add cannot handle a negative return */ + max = 0; + if (max <= biovec->bv_len && bio_sectors == 0) + return biovec->bv_len; + } else + max = biovec->bv_len; + + if (mddev->merge_check_needed) { + struct r10bio r10_bio; + int s; + r10_bio.sector = sector; + raid10_find_phys(conf, &r10_bio); + rcu_read_lock(); + for (s = 0; s < conf->copies; s++) { + int disk = r10_bio.devs[s].devnum; + struct md_rdev *rdev = rcu_dereference( + conf->mirrors[disk].rdev); + if (rdev && !test_bit(Faulty, &rdev->flags)) { + struct request_queue *q = + bdev_get_queue(rdev->bdev); + if (q->merge_bvec_fn) { + bvm->bi_sector = r10_bio.devs[s].addr + + rdev->data_offset; + bvm->bi_bdev = rdev->bdev; + max = min(max, q->merge_bvec_fn( + q, bvm, biovec)); + } + } + rdev = rcu_dereference(conf->mirrors[disk].replacement); + if (rdev && !test_bit(Faulty, &rdev->flags)) { + struct request_queue *q = + bdev_get_queue(rdev->bdev); + if (q->merge_bvec_fn) { + bvm->bi_sector = r10_bio.devs[s].addr + + rdev->data_offset; + bvm->bi_bdev = rdev->bdev; + max = min(max, q->merge_bvec_fn( + q, bvm, biovec)); + } + } + } + rcu_read_unlock(); + } + return max; } /* @@ -668,11 +711,12 @@ retry: disk = r10_bio->devs[slot].devnum; rdev = rcu_dereference(conf->mirrors[disk].replacement); if (rdev == NULL || test_bit(Faulty, &rdev->flags) || + test_bit(Unmerged, &rdev->flags) || r10_bio->devs[slot].addr + sectors > rdev->recovery_offset) rdev = rcu_dereference(conf->mirrors[disk].rdev); - if (rdev == NULL) - continue; - if (test_bit(Faulty, &rdev->flags)) + if (rdev == NULL || + test_bit(Faulty, &rdev->flags) || + test_bit(Unmerged, &rdev->flags)) continue; if (!test_bit(In_sync, &rdev->flags) && r10_bio->devs[slot].addr + sectors > rdev->recovery_offset) @@ -1134,12 +1178,14 @@ retry_write: blocked_rdev = rrdev; break; } - if (rrdev && test_bit(Faulty, &rrdev->flags)) + if (rrdev && (test_bit(Faulty, &rrdev->flags) + || test_bit(Unmerged, &rrdev->flags))) rrdev = NULL; r10_bio->devs[i].bio = NULL; r10_bio->devs[i].repl_bio = NULL; - if (!rdev || test_bit(Faulty, &rdev->flags)) { + if (!rdev || test_bit(Faulty, &rdev->flags) || + test_bit(Unmerged, &rdev->flags)) { set_bit(R10BIO_Degraded, &r10_bio->state); continue; } @@ -1490,6 +1536,7 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev) int mirror; int first = 0; int last = conf->raid_disks - 1; + struct request_queue *q = bdev_get_queue(rdev->bdev); if (mddev->recovery_cp < MaxSector) /* only hot-add to in-sync arrays, as recovery is @@ -1502,6 +1549,11 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev) if (rdev->raid_disk >= 0) first = last = rdev->raid_disk; + if (q->merge_bvec_fn) { + set_bit(Unmerged, &rdev->flags); + mddev->merge_check_needed = 1; + } + if (rdev->saved_raid_disk >= first && conf->mirrors[rdev->saved_raid_disk].rdev == NULL) mirror = rdev->saved_raid_disk; @@ -1521,11 +1573,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev) err = 0; disk_stack_limits(mddev->gendisk, rdev->bdev, rdev->data_offset << 9); - if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { - blk_queue_max_segments(mddev->queue, 1); - blk_queue_segment_boundary(mddev->queue, - PAGE_CACHE_SIZE - 1); - } conf->fullsync = 1; rcu_assign_pointer(p->replacement, rdev); break; @@ -1533,17 +1580,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev) disk_stack_limits(mddev->gendisk, rdev->bdev, rdev->data_offset << 9); - /* as we don't honour merge_bvec_fn, we must - * never risk violating it, so limit - * ->max_segments to one lying with a single - * page, as a one page request is never in - * violation. - */ - if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { - blk_queue_max_segments(mddev->queue, 1); - blk_queue_segment_boundary(mddev->queue, - PAGE_CACHE_SIZE - 1); - } p->head_position = 0; p->recovery_disabled = mddev->recovery_disabled - 1; @@ -1554,7 +1590,19 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev) rcu_assign_pointer(p->rdev, rdev); break; } - + if (err == 0 && test_bit(Unmerged, &rdev->flags)) { + /* Some requests might not have seen this new + * merge_bvec_fn. We must wait for them to complete + * before merging the device fully. + * First we make sure any code which has tested + * our function has submitted the request, then + * we wait for all outstanding requests to complete. + */ + synchronize_sched(); + raise_barrier(conf, 0); + lower_barrier(conf); + clear_bit(Unmerged, &rdev->flags); + } md_integrity_add_rdev(rdev, mddev); print_conf(conf); return err; @@ -2098,6 +2146,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10 d = r10_bio->devs[sl].devnum; rdev = rcu_dereference(conf->mirrors[d].rdev); if (rdev && + !test_bit(Unmerged, &rdev->flags) && test_bit(In_sync, &rdev->flags) && is_badblock(rdev, r10_bio->devs[sl].addr + sect, s, &first_bad, &bad_sectors) == 0) { @@ -2151,6 +2200,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10 d = r10_bio->devs[sl].devnum; rdev = rcu_dereference(conf->mirrors[d].rdev); if (!rdev || + test_bit(Unmerged, &rdev->flags) || !test_bit(In_sync, &rdev->flags)) continue; @@ -3273,15 +3323,6 @@ static int run(struct mddev *mddev) disk_stack_limits(mddev->gendisk, rdev->bdev, rdev->data_offset << 9); - /* as we don't honour merge_bvec_fn, we must never risk - * violating it, so limit max_segments to 1 lying - * within a single page. - */ - if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { - blk_queue_max_segments(mddev->queue, 1); - blk_queue_segment_boundary(mddev->queue, - PAGE_CACHE_SIZE - 1); - } disk->head_position = 0; } @@ -3345,8 +3386,7 @@ static int run(struct mddev *mddev) mddev->queue->backing_dev_info.ra_pages = 2* stripe; } - if (conf->near_copies < conf->raid_disks) - blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec); + blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec); if (md_integrity_register(mddev)) goto out_free_conf; -- 2.34.1