Files include/tree.h and include/queue.h include their own respective
(BSD 4-clause) license, as well as ext4_hash.c (BSD 2-clause).

The rest of the files are licensed under BSD 3-clause:

Copyright (c) 2013-2017 Grzegorz Kostka (kostka.grzegorz@gmail.com)
Copyright (c) 2015-2017 Kaho Ng (ngkaho1234@gmail.com)
Copyright (c) 2020-2024 Sigrid Solveig Haflínudóttir (sigrid@ftrv.se)

HelenOS: Copyright (c) 2012 Martin Sucha
         Copyright (c) 2012 Frantisek Princ

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Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

- Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.
- The name of the author may not be used to endorse or promote products
  derived from this software without specific prior written permission.

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