From f001a70cdc61c01452d42e8b32fd7c7842ef62d5 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 9 Jun 2009 14:30:31 +1000 Subject: [PATCH 1/3] md/raid5: use conf->raid_disks in preference to mddev->raid_disk mddev->raid_disks can be changed and any time by a request from user-space. It is a suggestion as to what number of raid_disks is desired. conf->raid_disks can only be changed by the raid5 module with suitable locks in place. It is a statement as to the current number of raid_disks. There are two places where the latter should be used, but the former is used. This can lead to a crash when reshaping an array. This patch changes to mddev-> to conf-> Signed-off-by: NeilBrown --- drivers/md/raid5.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 5d400aef8d9b4..75469e63ff10f 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3288,7 +3288,7 @@ static void unplug_slaves(mddev_t *mddev) int i; rcu_read_lock(); - for (i=0; iraid_disks; i++) { + for (i = 0; i < conf->raid_disks; i++) { mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev); if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) { struct request_queue *r_queue = bdev_get_queue(rdev->bdev); @@ -4034,7 +4034,7 @@ static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *ski * We don't need to check the 'failed' flag as when that gets set, * recovery aborts. */ - for (i=0; iraid_disks; i++) + for (i = 0; i < conf->raid_disks; i++) if (conf->disks[i].rdev == NULL) still_degraded = 1; From a8c906ca3f63d05f0d25490cf82276f73c6fe095 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 9 Jun 2009 14:39:59 +1000 Subject: [PATCH 2/3] md/raid5 - avoid deadlocks in get_active_stripe during reshape md has functionality to 'quiesce' and array so that all pending IO completed and no new IO starts. This is used to achieve a stable state before making internal changes. Currently this quiescing applies equally to normal IO, resync IO, and reshape IO. However there is a problem with applying it to reshape IO. Reshape can have multiple 'stripe_heads' that must be active together. If the quiesce come between allocating the first and the last of such a collection, then we deadlock, as the last will not be allocated until the quiesce is lifted, the quiesce will not be lifted until the first (which has been allocated) gets used, and that first cannot be used until the last is allocated. It is not necessary to inhibit reshape IO when a quiesce is requested. Those places in the code that require a full quiesce will ensure the reshape thread is not running at all. So allow reshape requests to get access to new stripe_heads without being blocked by a 'quiesce'. This only affects in-place reshapes (i.e. where the array does not grow or shrink) and these are only newly supported. So this patch is not needed in earlier kernels. Signed-off-by: NeilBrown --- drivers/md/raid5.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 75469e63ff10f..59f2ec0759b46 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -362,7 +362,7 @@ static void raid5_unplug_device(struct request_queue *q); static struct stripe_head * get_active_stripe(raid5_conf_t *conf, sector_t sector, - int previous, int noblock) + int previous, int noblock, int noquiesce) { struct stripe_head *sh; @@ -372,7 +372,7 @@ get_active_stripe(raid5_conf_t *conf, sector_t sector, do { wait_event_lock_irq(conf->wait_for_stripe, - conf->quiesce == 0, + conf->quiesce == 0 || noquiesce, conf->device_lock, /* nothing */); sh = __find_stripe(conf, sector, conf->generation - previous); if (!sh) { @@ -2671,7 +2671,7 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh, sector_t bn = compute_blocknr(sh, i, 1); sector_t s = raid5_compute_sector(conf, bn, 0, &dd_idx, NULL); - sh2 = get_active_stripe(conf, s, 0, 1); + sh2 = get_active_stripe(conf, s, 0, 1, 1); if (sh2 == NULL) /* so far only the early blocks of this stripe * have been requested. When later blocks @@ -2944,7 +2944,7 @@ static bool handle_stripe5(struct stripe_head *sh) /* Finish reconstruct operations initiated by the expansion process */ if (sh->reconstruct_state == reconstruct_state_result) { struct stripe_head *sh2 - = get_active_stripe(conf, sh->sector, 1, 1); + = get_active_stripe(conf, sh->sector, 1, 1, 1); if (sh2 && test_bit(STRIPE_EXPAND_SOURCE, &sh2->state)) { /* sh cannot be written until sh2 has been read. * so arrange for sh to be delayed a little @@ -3189,7 +3189,7 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page) if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) { struct stripe_head *sh2 - = get_active_stripe(conf, sh->sector, 1, 1); + = get_active_stripe(conf, sh->sector, 1, 1, 1); if (sh2 && test_bit(STRIPE_EXPAND_SOURCE, &sh2->state)) { /* sh cannot be written until sh2 has been read. * so arrange for sh to be delayed a little @@ -3675,7 +3675,7 @@ static int make_request(struct request_queue *q, struct bio * bi) (unsigned long long)logical_sector); sh = get_active_stripe(conf, new_sector, previous, - (bi->bi_rw&RWA_MASK)); + (bi->bi_rw&RWA_MASK), 0); if (sh) { if (unlikely(previous)) { /* expansion might have moved on while waiting for a @@ -3873,7 +3873,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) { int j; int skipped = 0; - sh = get_active_stripe(conf, stripe_addr+i, 0, 0); + sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1); set_bit(STRIPE_EXPANDING, &sh->state); atomic_inc(&conf->reshape_stripes); /* If any of this stripe is beyond the end of the old @@ -3922,7 +3922,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped if (last_sector >= mddev->dev_sectors) last_sector = mddev->dev_sectors - 1; while (first_sector <= last_sector) { - sh = get_active_stripe(conf, first_sector, 1, 0); + sh = get_active_stripe(conf, first_sector, 1, 0, 1); set_bit(STRIPE_EXPAND_SOURCE, &sh->state); set_bit(STRIPE_HANDLE, &sh->state); release_stripe(sh); @@ -4022,9 +4022,9 @@ static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *ski bitmap_cond_end_sync(mddev->bitmap, sector_nr); - sh = get_active_stripe(conf, sector_nr, 0, 1); + sh = get_active_stripe(conf, sector_nr, 0, 1, 0); if (sh == NULL) { - sh = get_active_stripe(conf, sector_nr, 0, 0); + sh = get_active_stripe(conf, sector_nr, 0, 0, 0); /* make sure we don't swamp the stripe cache if someone else * is trying to get access */ @@ -4086,7 +4086,7 @@ static int retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio) /* already done this stripe */ continue; - sh = get_active_stripe(conf, sector, 0, 1); + sh = get_active_stripe(conf, sector, 0, 1, 0); if (!sh) { /* failed to get a stripe - must wait */ From 0e6e0271a210817e202c8a4bfffbde3e3c0616d1 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 9 Jun 2009 16:32:22 +1000 Subject: [PATCH 3/3] md/raid5: fix bug in reshape code when chunk_size decreases. Now that we support changing the chunksize, we calculate "reshape_sectors" to be the max of number of sectors in old and new chunk size. However there is one please where we still use 'chunksize' rather than 'reshape_sectors'. This causes a reshape that reduces the size of chunks to freeze. Signed-off-by: NeilBrown --- drivers/md/raid5.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 59f2ec0759b46..bb37fb1b2d82d 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3916,7 +3916,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped raid5_compute_sector(conf, stripe_addr*(new_data_disks), 1, &dd_idx, NULL); last_sector = - raid5_compute_sector(conf, ((stripe_addr+conf->chunk_size/512) + raid5_compute_sector(conf, ((stripe_addr+reshape_sectors) *(new_data_disks) - 1), 1, &dd_idx, NULL); if (last_sector >= mddev->dev_sectors)