btrfs: comment waitqueue_active implied by locks

Suggested-by: Chris Mason <clm@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2015-10-10 18:35:10 +02:00
parent b666a9cd99
commit 33a9eca7e4
2 changed files with 11 additions and 1 deletions

View File

@ -810,7 +810,11 @@ static noinline void unlock_stripe(struct btrfs_raid_bio *rbio)
}
goto done_nolock;
} else if (waitqueue_active(&h->wait)) {
/*
* 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);

View File

@ -2950,6 +2950,9 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
atomic_set(&log_root_tree->log_commit[index2], 0);
mutex_unlock(&log_root_tree->log_mutex);
/*
* The barrier before waitqueue_active is implied by mutex_unlock
*/
if (waitqueue_active(&log_root_tree->log_commit_wait[index2]))
wake_up(&log_root_tree->log_commit_wait[index2]);
out:
@ -2961,6 +2964,9 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
atomic_set(&root->log_commit[index1], 0);
mutex_unlock(&root->log_mutex);
/*
* The barrier before waitqueue_active is implied by mutex_unlock
*/
if (waitqueue_active(&root->log_commit_wait[index1]))
wake_up(&root->log_commit_wait[index1]);
return ret;