btrfs: remove unused btrfs_try_tree_write_lock()

btrfs_try_tree_write_lock() has been unused since commit
50b21d7 ("btrfs: submit a writeback bio per extent_buffer").
Remove it as we don't need it anymore.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/locking.c

@@ -161,21 +161,6 @@ int btrfs_try_tree_read_lock(struct extent_buffer *eb)
 	return 0;
 }
 
-/*
- * Try-lock for write.
- *
- * Return 1 if the rwlock has been taken, 0 otherwise
- */
-int btrfs_try_tree_write_lock(struct extent_buffer *eb)
-{
-	if (down_write_trylock(&eb->lock)) {
-		btrfs_set_eb_lock_owner(eb, current->pid);
-		trace_btrfs_try_tree_write_lock(eb);
-		return 1;
-	}
-	return 0;
-}
-
 /*
  * Release read lock.
  */

fs/btrfs/locking.h

@@ -180,7 +180,6 @@ static inline void btrfs_tree_read_lock(struct extent_buffer *eb)
 
 void btrfs_tree_read_unlock(struct extent_buffer *eb);
 int btrfs_try_tree_read_lock(struct extent_buffer *eb);
-int btrfs_try_tree_write_lock(struct extent_buffer *eb);
 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
 struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root);
 struct extent_buffer *btrfs_try_read_lock_root_node(struct btrfs_root *root);

include/trace/events/btrfs.h

@@ -2344,7 +2344,6 @@ DEFINE_BTRFS_LOCK_EVENT(btrfs_tree_read_unlock_blocking);
 DEFINE_BTRFS_LOCK_EVENT(btrfs_set_lock_blocking_read);
 DEFINE_BTRFS_LOCK_EVENT(btrfs_set_lock_blocking_write);
 DEFINE_BTRFS_LOCK_EVENT(btrfs_try_tree_read_lock);
-DEFINE_BTRFS_LOCK_EVENT(btrfs_try_tree_write_lock);
 DEFINE_BTRFS_LOCK_EVENT(btrfs_tree_read_lock_atomic);
 
 DECLARE_EVENT_CLASS(btrfs__space_info_update,