btrfs: Add WARN_ON() for double lock in btrfs_tree_lock()
When a task trying to double lock a extent buffer, there are no lockdep warning about it because this lock may be in "blocking_lock" state, and make us hard to debug. This patch add a WARN_ON() for above condition, it can not report all deadlock cases(as lock between tasks), but at least helps us some. Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
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@ -241,6 +241,7 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb)
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*/
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*/
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void btrfs_tree_lock(struct extent_buffer *eb)
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void btrfs_tree_lock(struct extent_buffer *eb)
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{
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{
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WARN_ON(eb->lock_owner == current->pid);
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again:
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again:
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wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0);
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wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0);
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wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
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wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
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