If I read code correctly, current wait_for_stripe actually has 2 usage:
- wait for there is enough free stripe cache, triggered when
get_free_stripe() failed. This is what wait_for_stripe intend
for literally.
- wait for quiesce == 0 or
active_aligned_reads == 0 && active_stripes == 0
It has nothing to do with wait_for_stripe literally, and releasing
an active stripe won't actually wake them up. On the contrary, wake_up
from under this case won't actually wake up the process waiting for
an free stripe being available.
Hence, we'd better split wait_for_stripe, and here I introduce
wait_for_quiesce for the second usage. The name may not well taken, or
even taken wrongly. Feel free to correct me then.
This is also a prepare patch for next patch: make wait_for_stripe
exclusive.
Signed-off-by: Yuanhan Liu <yuanhan.liu@xxxxxxxxxxxxxxx>
---
drivers/md/raid5.c | 13 +++++++------
drivers/md/raid5.h | 1 +
2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9716319..b7e385f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -667,7 +667,7 @@ get_active_stripe(struct r5conf *conf, sector_t sector,
spin_lock_irq(conf->hash_locks + hash);
do {
- wait_event_lock_irq(conf->wait_for_stripe,
+ wait_event_lock_irq(conf->wait_for_quiesce,
conf->quiesce == 0 || noquiesce,
*(conf->hash_locks + hash));
sh = __find_stripe(conf, sector, conf->generation - previous);
@@ -4725,7 +4725,7 @@ static void raid5_align_endio(struct bio *bi, int error)
raid_bi, 0);
bio_endio(raid_bi, 0);
if (atomic_dec_and_test(&conf->active_aligned_reads))
- wake_up(&conf->wait_for_stripe);
+ wake_up(&conf->wait_for_quiesce);
return;
}
@@ -4820,7 +4820,7 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
align_bi->bi_iter.bi_sector += rdev->data_offset;
spin_lock_irq(&conf->device_lock);
- wait_event_lock_irq(conf->wait_for_stripe,
+ wait_event_lock_irq(conf->wait_for_quiesce,
conf->quiesce == 0,
conf->device_lock);
atomic_inc(&conf->active_aligned_reads);
@@ -5659,7 +5659,7 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
bio_endio(raid_bio, 0);
}
if (atomic_dec_and_test(&conf->active_aligned_reads))
- wake_up(&conf->wait_for_stripe);
+ wake_up(&conf->wait_for_quiesce);
return handled;
}
@@ -6390,6 +6390,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
goto abort;
spin_lock_init(&conf->device_lock);
seqcount_init(&conf->gen_lock);
+ init_waitqueue_head(&conf->wait_for_quiesce);
init_waitqueue_head(&conf->wait_for_stripe);
init_waitqueue_head(&conf->wait_for_overlap);
INIT_LIST_HEAD(&conf->handle_list);
@@ -7413,7 +7414,7 @@ static void raid5_quiesce(struct mddev *mddev, int state)
* active stripes can drain
*/
conf->quiesce = 2;
- wait_event_cmd(conf->wait_for_stripe,
+ wait_event_cmd(conf->wait_for_quiesce,
atomic_read(&conf->active_stripes) == 0 &&
atomic_read(&conf->active_aligned_reads) == 0,
unlock_all_device_hash_locks_irq(conf),
@@ -7427,7 +7428,7 @@ static void raid5_quiesce(struct mddev *mddev, int state)
case 0: /* re-enable writes */
lock_all_device_hash_locks_irq(conf);
conf->quiesce = 0;
- wake_up(&conf->wait_for_stripe);
+ wake_up(&conf->wait_for_quiesce);
wake_up(&conf->wait_for_overlap);
unlock_all_device_hash_locks_irq(conf);
break;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 7dc0dd8..fab53a3 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -508,6 +508,7 @@ struct r5conf {
struct list_head inactive_list[NR_STRIPE_HASH_LOCKS];
atomic_t empty_inactive_list_nr;
struct llist_head released_stripes;
+ wait_queue_head_t wait_for_quiesce;
wait_queue_head_t wait_for_stripe;
wait_queue_head_t wait_for_overlap;
unsigned long cache_state;
--
1.9.0
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