btrfs: comment the rest of implicit barriers before waitqueue_active
There are atomic operations that imply the barrier for waitqueue_active mixed in an if-condition. Signed-off-by: David Sterba <dsterba@suse.com>
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ee86395458
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@ -463,6 +463,10 @@ static int __btrfs_add_delayed_deletion_item(struct btrfs_delayed_node *node,
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static void finish_one_item(struct btrfs_delayed_root *delayed_root)
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{
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int seq = atomic_inc_return(&delayed_root->items_seq);
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/*
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* atomic_dec_return implies a barrier for waitqueue_active
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*/
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if ((atomic_dec_return(&delayed_root->items) <
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BTRFS_DELAYED_BACKGROUND || seq % BTRFS_DELAYED_BATCH == 0) &&
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waitqueue_active(&delayed_root->wait))
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@ -802,6 +802,9 @@ static void run_one_async_done(struct btrfs_work *work)
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limit = btrfs_async_submit_limit(fs_info);
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limit = limit * 2 / 3;
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/*
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* atomic_dec_return implies a barrier for waitqueue_active
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*/
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if (atomic_dec_return(&fs_info->nr_async_submits) < limit &&
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waitqueue_active(&fs_info->async_submit_wait))
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wake_up(&fs_info->async_submit_wait);
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@ -1096,6 +1096,9 @@ static noinline void async_cow_submit(struct btrfs_work *work)
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nr_pages = (async_cow->end - async_cow->start + PAGE_CACHE_SIZE) >>
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PAGE_CACHE_SHIFT;
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/*
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* atomic_sub_return implies a barrier for waitqueue_active
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*/
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if (atomic_sub_return(nr_pages, &root->fs_info->async_delalloc_pages) <
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5 * 1024 * 1024 &&
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waitqueue_active(&root->fs_info->async_submit_wait))
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@ -79,6 +79,9 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw)
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write_lock(&eb->lock);
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WARN_ON(atomic_read(&eb->spinning_writers));
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atomic_inc(&eb->spinning_writers);
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/*
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* atomic_dec_and_test implies a barrier for waitqueue_active
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*/
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if (atomic_dec_and_test(&eb->blocking_writers) &&
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waitqueue_active(&eb->write_lock_wq))
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wake_up(&eb->write_lock_wq);
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@ -86,6 +89,9 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw)
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BUG_ON(atomic_read(&eb->blocking_readers) == 0);
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read_lock(&eb->lock);
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atomic_inc(&eb->spinning_readers);
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/*
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* atomic_dec_and_test implies a barrier for waitqueue_active
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*/
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if (atomic_dec_and_test(&eb->blocking_readers) &&
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waitqueue_active(&eb->read_lock_wq))
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wake_up(&eb->read_lock_wq);
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@ -229,6 +235,9 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb)
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}
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btrfs_assert_tree_read_locked(eb);
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WARN_ON(atomic_read(&eb->blocking_readers) == 0);
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/*
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* atomic_dec_and_test implies a barrier for waitqueue_active
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*/
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if (atomic_dec_and_test(&eb->blocking_readers) &&
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waitqueue_active(&eb->read_lock_wq))
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wake_up(&eb->read_lock_wq);
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@ -345,6 +345,9 @@ loop_lock:
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pending = pending->bi_next;
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cur->bi_next = NULL;
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/*
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* atomic_dec_return implies a barrier for waitqueue_active
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*/
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if (atomic_dec_return(&fs_info->nr_async_bios) < limit &&
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waitqueue_active(&fs_info->async_submit_wait))
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wake_up(&fs_info->async_submit_wait);
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