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md/raid5: add simple plugging infrastructure.
md/raid5 uses the plugging infrastructure provided by the block layer and 'struct request_queue'. However when we plug raid5 under dm there is no request queue so we cannot use that. So create a similar infrastructure that is much lighter weight and use it for raid5. Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown
parent
11d8a6e371
commit
2ac8740151
@ -386,6 +386,51 @@ void md_barrier_request(mddev_t *mddev, struct bio *bio)
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}
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EXPORT_SYMBOL(md_barrier_request);
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/* Support for plugging.
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* This mirrors the plugging support in request_queue, but does not
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* require having a whole queue
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*/
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static void plugger_work(struct work_struct *work)
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{
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struct plug_handle *plug =
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container_of(work, struct plug_handle, unplug_work);
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plug->unplug_fn(plug);
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}
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static void plugger_timeout(unsigned long data)
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{
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struct plug_handle *plug = (void *)data;
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kblockd_schedule_work(NULL, &plug->unplug_work);
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}
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void plugger_init(struct plug_handle *plug,
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void (*unplug_fn)(struct plug_handle *))
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{
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plug->unplug_flag = 0;
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plug->unplug_fn = unplug_fn;
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init_timer(&plug->unplug_timer);
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plug->unplug_timer.function = plugger_timeout;
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plug->unplug_timer.data = (unsigned long)plug;
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INIT_WORK(&plug->unplug_work, plugger_work);
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}
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EXPORT_SYMBOL_GPL(plugger_init);
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void plugger_set_plug(struct plug_handle *plug)
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{
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if (!test_and_set_bit(PLUGGED_FLAG, &plug->unplug_flag))
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mod_timer(&plug->unplug_timer, jiffies + msecs_to_jiffies(3)+1);
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}
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EXPORT_SYMBOL_GPL(plugger_set_plug);
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int plugger_remove_plug(struct plug_handle *plug)
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{
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if (test_and_clear_bit(PLUGGED_FLAG, &plug->unplug_flag)) {
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del_timer(&plug->unplug_timer);
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return 1;
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} else
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return 0;
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}
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EXPORT_SYMBOL_GPL(plugger_remove_plug);
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static inline mddev_t *mddev_get(mddev_t *mddev)
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{
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atomic_inc(&mddev->active);
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@ -29,6 +29,26 @@
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typedef struct mddev_s mddev_t;
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typedef struct mdk_rdev_s mdk_rdev_t;
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/* generic plugging support - like that provided with request_queue,
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* but does not require a request_queue
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*/
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struct plug_handle {
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void (*unplug_fn)(struct plug_handle *);
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struct timer_list unplug_timer;
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struct work_struct unplug_work;
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unsigned long unplug_flag;
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};
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#define PLUGGED_FLAG 1
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void plugger_init(struct plug_handle *plug,
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void (*unplug_fn)(struct plug_handle *));
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void plugger_set_plug(struct plug_handle *plug);
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int plugger_remove_plug(struct plug_handle *plug);
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static inline void plugger_flush(struct plug_handle *plug)
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{
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del_timer_sync(&plug->unplug_timer);
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cancel_work_sync(&plug->unplug_work);
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}
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/*
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* MD's 'extended' device
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*/
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@ -201,11 +201,11 @@ static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
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if (test_bit(STRIPE_HANDLE, &sh->state)) {
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if (test_bit(STRIPE_DELAYED, &sh->state)) {
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list_add_tail(&sh->lru, &conf->delayed_list);
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blk_plug_device(conf->mddev->queue);
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plugger_set_plug(&conf->plug);
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} else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
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sh->bm_seq - conf->seq_write > 0) {
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list_add_tail(&sh->lru, &conf->bitmap_list);
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blk_plug_device(conf->mddev->queue);
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plugger_set_plug(&conf->plug);
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} else {
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clear_bit(STRIPE_BIT_DELAY, &sh->state);
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list_add_tail(&sh->lru, &conf->handle_list);
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@ -434,7 +434,7 @@ static int has_failed(raid5_conf_t *conf)
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}
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static void unplug_slaves(mddev_t *mddev);
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static void raid5_unplug_device(struct request_queue *q);
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static void raid5_unplug_device(raid5_conf_t *conf);
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static struct stripe_head *
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get_active_stripe(raid5_conf_t *conf, sector_t sector,
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@ -464,7 +464,7 @@ get_active_stripe(raid5_conf_t *conf, sector_t sector,
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< (conf->max_nr_stripes *3/4)
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|| !conf->inactive_blocked),
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conf->device_lock,
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raid5_unplug_device(conf->mddev->queue)
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raid5_unplug_device(conf)
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);
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conf->inactive_blocked = 0;
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} else
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@ -3618,7 +3618,7 @@ static void raid5_activate_delayed(raid5_conf_t *conf)
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list_add_tail(&sh->lru, &conf->hold_list);
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}
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} else
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blk_plug_device(conf->mddev->queue);
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plugger_set_plug(&conf->plug);
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}
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static void activate_bit_delay(raid5_conf_t *conf)
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@ -3659,23 +3659,33 @@ static void unplug_slaves(mddev_t *mddev)
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rcu_read_unlock();
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}
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static void raid5_unplug_device(struct request_queue *q)
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static void raid5_unplug_device(raid5_conf_t *conf)
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{
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mddev_t *mddev = q->queuedata;
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raid5_conf_t *conf = mddev->private;
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unsigned long flags;
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spin_lock_irqsave(&conf->device_lock, flags);
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if (blk_remove_plug(q)) {
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if (plugger_remove_plug(&conf->plug)) {
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conf->seq_flush++;
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raid5_activate_delayed(conf);
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}
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md_wakeup_thread(mddev->thread);
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md_wakeup_thread(conf->mddev->thread);
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spin_unlock_irqrestore(&conf->device_lock, flags);
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unplug_slaves(mddev);
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unplug_slaves(conf->mddev);
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}
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static void raid5_unplug(struct plug_handle *plug)
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{
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raid5_conf_t *conf = container_of(plug, raid5_conf_t, plug);
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raid5_unplug_device(conf);
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}
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static void raid5_unplug_queue(struct request_queue *q)
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{
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mddev_t *mddev = q->queuedata;
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raid5_unplug_device(mddev->private);
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}
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int md_raid5_congested(mddev_t *mddev, int bits)
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@ -4085,7 +4095,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
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* add failed due to overlap. Flush everything
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* and wait a while
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*/
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raid5_unplug_device(mddev->queue);
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raid5_unplug_device(conf);
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release_stripe(sh);
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schedule();
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goto retry;
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@ -5178,6 +5188,7 @@ static int run(mddev_t *mddev)
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mdname(mddev));
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md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
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plugger_init(&conf->plug, raid5_unplug);
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if (mddev->queue) {
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/* read-ahead size must cover two whole stripes, which
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* is 2 * (datadisks) * chunksize where 'n' is the
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@ -5197,7 +5208,7 @@ static int run(mddev_t *mddev)
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mddev->queue->queue_lock = &conf->device_lock;
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mddev->queue->unplug_fn = raid5_unplug_device;
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mddev->queue->unplug_fn = raid5_unplug_queue;
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chunk_size = mddev->chunk_sectors << 9;
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blk_queue_io_min(mddev->queue, chunk_size);
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@ -5229,7 +5240,7 @@ static int stop(mddev_t *mddev)
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mddev->thread = NULL;
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if (mddev->queue)
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mddev->queue->backing_dev_info.congested_fn = NULL;
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blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
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plugger_flush(&conf->plug); /* the unplug fn references 'conf'*/
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free_conf(conf);
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mddev->private = NULL;
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mddev->to_remove = &raid5_attrs_group;
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@ -398,6 +398,9 @@ struct raid5_private_data {
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* (fresh device added).
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* Cleared when a sync completes.
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*/
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struct plug_handle plug;
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/* per cpu variables */
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struct raid5_percpu {
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struct page *spare_page; /* Used when checking P/Q in raid6 */
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