RAID5: revert e9e4c377e2
to fix a livelock
Revert commit e9e4c377e2f563(md/raid5: per hash value and exclusive wait_for_stripe) The problem is raid5_get_active_stripe waits on conf->wait_for_stripe[hash]. Assume hash is 0. My test release stripes in this order: - release all stripes with hash 0 - raid5_get_active_stripe still sleeps since active_stripes > max_nr_stripes * 3 / 4 - release all stripes with hash other than 0. active_stripes becomes 0 - raid5_get_active_stripe still sleeps, since nobody wakes up wait_for_stripe[0] The system live locks. The problem is active_stripes isn't a per-hash count. Revert the patch makes the live lock go away. Cc: stable@vger.kernel.org (v4.2+) Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com> Cc: NeilBrown <neilb@suse.de> Signed-off-by: Shaohua Li <shli@fb.com>
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27a353c026
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6ab2a4b806
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@ -340,8 +340,7 @@ static void release_inactive_stripe_list(struct r5conf *conf,
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int hash)
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int hash)
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{
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{
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int size;
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int size;
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unsigned long do_wakeup = 0;
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bool do_wakeup = false;
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int i = 0;
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unsigned long flags;
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unsigned long flags;
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if (hash == NR_STRIPE_HASH_LOCKS) {
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if (hash == NR_STRIPE_HASH_LOCKS) {
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@ -362,19 +361,15 @@ static void release_inactive_stripe_list(struct r5conf *conf,
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!list_empty(list))
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!list_empty(list))
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atomic_dec(&conf->empty_inactive_list_nr);
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atomic_dec(&conf->empty_inactive_list_nr);
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list_splice_tail_init(list, conf->inactive_list + hash);
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list_splice_tail_init(list, conf->inactive_list + hash);
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do_wakeup |= 1 << hash;
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do_wakeup = true;
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spin_unlock_irqrestore(conf->hash_locks + hash, flags);
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spin_unlock_irqrestore(conf->hash_locks + hash, flags);
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}
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}
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size--;
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size--;
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hash--;
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hash--;
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}
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}
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for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++) {
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if (do_wakeup & (1 << i))
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wake_up(&conf->wait_for_stripe[i]);
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}
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if (do_wakeup) {
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if (do_wakeup) {
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wake_up(&conf->wait_for_stripe);
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if (atomic_read(&conf->active_stripes) == 0)
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if (atomic_read(&conf->active_stripes) == 0)
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wake_up(&conf->wait_for_quiescent);
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wake_up(&conf->wait_for_quiescent);
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if (conf->retry_read_aligned)
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if (conf->retry_read_aligned)
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@ -687,15 +682,14 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
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if (!sh) {
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if (!sh) {
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set_bit(R5_INACTIVE_BLOCKED,
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set_bit(R5_INACTIVE_BLOCKED,
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&conf->cache_state);
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&conf->cache_state);
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wait_event_exclusive_cmd(
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wait_event_lock_irq(
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conf->wait_for_stripe[hash],
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conf->wait_for_stripe,
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!list_empty(conf->inactive_list + hash) &&
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!list_empty(conf->inactive_list + hash) &&
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(atomic_read(&conf->active_stripes)
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(atomic_read(&conf->active_stripes)
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< (conf->max_nr_stripes * 3 / 4)
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< (conf->max_nr_stripes * 3 / 4)
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|| !test_bit(R5_INACTIVE_BLOCKED,
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|| !test_bit(R5_INACTIVE_BLOCKED,
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&conf->cache_state)),
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&conf->cache_state)),
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spin_unlock_irq(conf->hash_locks + hash),
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*(conf->hash_locks + hash));
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spin_lock_irq(conf->hash_locks + hash));
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clear_bit(R5_INACTIVE_BLOCKED,
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clear_bit(R5_INACTIVE_BLOCKED,
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&conf->cache_state);
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&conf->cache_state);
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} else {
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} else {
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@ -720,9 +714,6 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
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}
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}
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} while (sh == NULL);
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} while (sh == NULL);
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if (!list_empty(conf->inactive_list + hash))
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wake_up(&conf->wait_for_stripe[hash]);
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spin_unlock_irq(conf->hash_locks + hash);
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spin_unlock_irq(conf->hash_locks + hash);
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return sh;
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return sh;
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}
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}
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@ -2202,7 +2193,7 @@ static int resize_stripes(struct r5conf *conf, int newsize)
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cnt = 0;
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cnt = 0;
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list_for_each_entry(nsh, &newstripes, lru) {
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list_for_each_entry(nsh, &newstripes, lru) {
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lock_device_hash_lock(conf, hash);
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lock_device_hash_lock(conf, hash);
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wait_event_exclusive_cmd(conf->wait_for_stripe[hash],
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wait_event_cmd(conf->wait_for_stripe,
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!list_empty(conf->inactive_list + hash),
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!list_empty(conf->inactive_list + hash),
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unlock_device_hash_lock(conf, hash),
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unlock_device_hash_lock(conf, hash),
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lock_device_hash_lock(conf, hash));
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lock_device_hash_lock(conf, hash));
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@ -6521,9 +6512,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
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seqcount_init(&conf->gen_lock);
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seqcount_init(&conf->gen_lock);
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mutex_init(&conf->cache_size_mutex);
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mutex_init(&conf->cache_size_mutex);
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init_waitqueue_head(&conf->wait_for_quiescent);
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init_waitqueue_head(&conf->wait_for_quiescent);
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for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++) {
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init_waitqueue_head(&conf->wait_for_stripe);
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init_waitqueue_head(&conf->wait_for_stripe[i]);
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}
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init_waitqueue_head(&conf->wait_for_overlap);
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init_waitqueue_head(&conf->wait_for_overlap);
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INIT_LIST_HEAD(&conf->handle_list);
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INIT_LIST_HEAD(&conf->handle_list);
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INIT_LIST_HEAD(&conf->hold_list);
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INIT_LIST_HEAD(&conf->hold_list);
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@ -524,7 +524,7 @@ struct r5conf {
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atomic_t empty_inactive_list_nr;
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atomic_t empty_inactive_list_nr;
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struct llist_head released_stripes;
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struct llist_head released_stripes;
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wait_queue_head_t wait_for_quiescent;
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wait_queue_head_t wait_for_quiescent;
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wait_queue_head_t wait_for_stripe[NR_STRIPE_HASH_LOCKS];
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wait_queue_head_t wait_for_stripe;
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wait_queue_head_t wait_for_overlap;
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wait_queue_head_t wait_for_overlap;
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unsigned long cache_state;
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unsigned long cache_state;
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#define R5_INACTIVE_BLOCKED 1 /* release of inactive stripes blocked,
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#define R5_INACTIVE_BLOCKED 1 /* release of inactive stripes blocked,
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