[PATCH] Btrfs: remove unused wait in btrfs_stripe_hash

[PATCH] Btrfs: remove unused wait in btrfs_stripe_hash

[Liu Bo]

In fact nobody is waiting on @wait's waitqueue, it can be safely
removed.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
---
 fs/btrfs/ctree.h  |  1 -
 fs/btrfs/raid56.c | 10 ----------
 2 files changed, 11 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 13c260b..b2e09fe 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -679,7 +679,6 @@ enum btrfs_orphan_cleanup_state {
 /* used by the raid56 code to lock stripes for read/modify/write */
 struct btrfs_stripe_hash {
 	struct list_head hash_list;
-	wait_queue_head_t wait;
 	spinlock_t lock;
 };
 
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 3940906..9fa45e0 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -231,7 +231,6 @@ int btrfs_alloc_stripe_hash_table(struct btrfs_fs_info *info)
 		cur = h + i;
 		INIT_LIST_HEAD(&cur->hash_list);
 		spin_lock_init(&cur->lock);
-		init_waitqueue_head(&cur->wait);
 	}
 
 	x = cmpxchg(&info->stripe_hash_table, NULL, table);
@@ -815,15 +814,6 @@ static noinline void unlock_stripe(struct btrfs_raid_bio *rbio)
 			}
 
 			goto done_nolock;
-			/*
-			 * The barrier for this waitqueue_active is not needed,
-			 * we're protected by h->lock and can't miss a wakeup.
-			 */
-		} else if (waitqueue_active(&h->wait)) {
-			spin_unlock(&rbio->bio_list_lock);
-			spin_unlock_irqrestore(&h->lock, flags);
-			wake_up(&h->wait);
-			goto done_nolock;
 		}
 	}
 done:
-- 
2.9.4

Re: [PATCH] Btrfs: remove unused wait in btrfs_stripe_hash

[David Sterba]

On Fri, Dec 22, 2017 at 04:23:01PM -0700, Liu Bo wrote:
> In fact nobody is waiting on @wait's waitqueue, it can be safely
> removed.
> 
> Signed-off-by: Liu Bo <bo.li.liu@oracle.com>

Reviewed-by: David Sterba <dsterba@suse.com>