btrfs: use cached state when falling back from NOCoW write to CoW write

We have a cached extent state record from the previous extent locking so
we can use when setting the EXTENT_NORESERVE in the range, allowing the
operation to be faster if the extent io tree is relatively large.

Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Filipe Manana <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: fdmanana

fs/btrfs/inode.c

@@ -1754,7 +1754,8 @@ static int fallback_to_cow(struct btrfs_inode *inode,
 		spin_unlock(&sinfo->lock);
 
 		if (count > 0)
-			btrfs_clear_extent_bits(io_tree, start, end, EXTENT_NORESERVE);
+			btrfs_clear_extent_bit(io_tree, start, end, EXTENT_NORESERVE,
+					       &cached_state);
 	}
 	btrfs_unlock_extent(io_tree, start, end, &cached_state);