akiradeveloper · Oct 22, 2026 · Oct 22, 2026 · Oct 21, 2026 · Oct 21, 2026 · Oct 21, 2026
diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,11 @@
+2026-10-22  Akira Hayakawa  <ruby.wktk@gmail.com>
+
+	* v2.2.20
+	* Fix build errors with 7.2 kernel
+	* Refactor
+	* Require Linux 4.18 or later
+	* Update copyright year
+
 2025-07-10  Akira Hayakawa  <ruby.wktk@gmail.com>
 
 	* v2.2.19

diff --git a/Makefile b/Makefile
@@ -1,4 +1,4 @@
-MODULE_VERSION ?= 2.2.19
+MODULE_VERSION ?= 2.2.20
 DKMS_DIR := /usr/src/dm-writeboost-$(MODULE_VERSION)
 DKMS_KEY := -m dm-writeboost -v $(MODULE_VERSION)
 

diff --git a/README.md b/README.md
@@ -1,66 +1,85 @@
-# dm-writeboost 
+# dm-writeboost
 
 ![CI](https://github.com/akiradeveloper/dm-writeboost/actions/workflows/ci.yml/badge.svg)
 
 Log-structured Caching for Linux
 
 ## Overview
-dm-writeboost is originated from [Disk Caching Disk (DCD)](http://www.ele.uri.edu/research/hpcl/DCD/DCD.html).
-DCD, implemented in Solaris, is an OS-level IO controller that builds logs from in-coming writes
-(data and metadata) and then writes the logs sequentially similar to log-structured filesystem.
-dm-writeboost implements the concept on Linux's device-mapper in more sophisticated way.
-As a further extension, dm-writeboost supports read-caching which also writes data sequentially.
-
-## Documents
-- [dm-writeboost-quickstart](https://docs.google.com/presentation/d/1v-L8Ma138o7jNBFqRl0epyc1Lji3XhUH1RGj8p7DVe8/edit?usp=sharing)  
-- doc/dm-writeboost-readme.txt  
-- [dm-writeboost-internal](https://docs.google.com/presentation/d/1mDh5ct3OR-eRxBbci3LQgaTvUFx9WTLw-kkBxNBeTD8/edit?usp=sharing)  
+
+dm-writeboost is inspired by [Disk Caching Disk (DCD)](http://www.ele.uri.edu/research/hpcl/DCD/DCD.html).
+Originally implemented in Solaris, DCD is an OS-level I/O controller that groups incoming writes
+(data and metadata) into logs and writes them sequentially, much like a log-structured file system.
+dm-writeboost brings this approach to the Linux device-mapper framework and extends it with features such as
+read caching, which also writes cached data sequentially.
+
+## Documentation
+
+- [Quickstart](https://docs.google.com/presentation/d/1v-L8Ma138o7jNBFqRl0epyc1Lji3XhUH1RGj8p7DVe8/edit?usp=sharing)
+- [Usage and reference](doc/dm-writeboost-readme.txt)
+- [Internals](https://docs.google.com/presentation/d/1mDh5ct3OR-eRxBbci3LQgaTvUFx9WTLw-kkBxNBeTD8/edit?usp=sharing)
 - [Wiki](https://github.com/akiradeveloper/dm-writeboost/wiki)
 
 ## Features
-* **Durable**: Any power failure can't break consistency because each log consists of data, metadata and
-  the checksum of the log itself.  
-* **Lifetime**: Other caching software (e.g. dm-cache) separates data and
-  metadata and therefore submits writes to SSD too frequently. dm-writeboost,
-  on the other hand, submits only one  writes for hundreds of data and
-  metadata updates so the SSD lives longer since SSD's lifetime depends on
-  how many writes are submitted.  
-* **Fast**: Since the sequential write is the best I/O pattern for every SSD and the code base is optimized for
-  in-coming random writes, the write performance is the best among all caching drivers including dm-cache and
-  bcache.  
-* **Portable**: Requires Linux kernel 4.18 or later.
+
+- **Durable**: Each log contains data, metadata, and a checksum, allowing dm-writeboost to verify logs
+  and recover a consistent cache state after a power failure.
+- **SSD endurance**: Batches data and metadata updates into a single log write, reducing how often
+  write requests are submitted to the SSD.
+- **Fast**: Optimized for incoming random writes, which are combined into sequential writes to the
+  cache device.
+- **Portable**: Requires Linux kernel 4.18 or later.
 
 ## Usage
-- **Install**: `sudo make install` to install and `sudo make uninstall` to uninstall.
-  `sudo make uninstall MODULE_VERSION=xxx` can uninstall specific version that's installed.
-  DKMS is required so please install it beforehand. (usually available in package system)
-- **Make a device**: Make a script to build a caching device. Please read doc/dm-writeboost-readme.txt for
-  the dmsetup command detail.
-  After reboot, you need to rebuild the caching device rather than reformatting as in the initial setup.
+
+### Install
+
+Install DKMS using your distribution's package manager, then run `sudo make install` to install the module.
+Run `sudo make uninstall` to uninstall it. To uninstall a specific installed version, set `MODULE_VERSION`,
+for example: `sudo make uninstall MODULE_VERSION=2.2.20`.
+
+### Create a device
+
+You can create a dm-writeboost device using either of these tools:
+
+- `dmsetup`: See the [usage and reference guide](doc/dm-writeboost-readme.txt) for the device table format
+  and setup instructions.
+- `writeboost-cli create`: Part of [dm-writeboost-tools](https://github.com/akiradeveloper/dm-writeboost-tools).
+  See its [create command documentation](https://github.com/akiradeveloper/dm-writeboost-tools#create) for examples.
+
+You can optionally automate device creation with a script, including recreating the device mapping at boot.
+
+### Resume after a reboot
+
+Recreate the device mapping using the same backing device, cache device, and settings, preserving the
+existing cache data. This allows dm-writeboost to replay the logs and restore the cache state.
+To resume an existing cache with `writeboost-cli create`, omit `--reformat`.
 
 ## Distribution Packages
-- [Debian](https://packages.debian.org/search?keywords=dm-writeboost-dkms)  
-- [Ubuntu](https://packages.ubuntu.com/search?keywords=dm-writeboost-dkms)  
+
+- [Debian](https://packages.debian.org/search?keywords=dm-writeboost-dkms)
+- [Ubuntu](https://packages.ubuntu.com/search?keywords=dm-writeboost-dkms)
 
 ## Related Projects
-* https://github.com/akiradeveloper/dm-writeboost-tools: Tools to help users analyze the state of the cache device  
-* https://gitlab.com/onlyjob/writeboost: A management tool including init script  
-* https://github.com/akiradeveloper/device-mapper-tests: Testing framework written in Rust
-
-## Related works
-* Y. Hu and Q. Yang -- DCD Disk Caching Disk: A New Approach for Boosting I/O Performance (1995)
-  (http://www.ele.uri.edu/research/hpcl/DCD/DCD.html)  
-* G. Soundararajan et. al. -- Extending SSD Lifetimes with Disk-Based Write Caches (2010)
-  (https://www.usenix.org/conference/fast-10/extending-ssd-lifetimes-disk-based-write-caches)  
-* Y. Oh -- SSD RAID as Cache (SRC) with Log-structured Approach for Performance and Reliability (2014)
-  (https://ysoh.files.wordpress.com/2009/05/dm-src-ibm.pdf)
+
+- [dm-writeboost-tools](https://github.com/akiradeveloper/dm-writeboost-tools): Tools for managing dm-writeboost
+  devices and inspecting cache state, including `writeboost-cli`.
+- [writeboost](https://gitlab.com/onlyjob/writeboost): A management tool with an init script.
+- [device-mapper-tests](https://github.com/akiradeveloper/device-mapper-tests): A testing framework written in Rust.
+
+## Related Work
+
+- Y. Hu and Q. Yang — [DCD Disk Caching Disk: A New Approach for Boosting I/O Performance](http://www.ele.uri.edu/research/hpcl/DCD/DCD.html) (1995).
+- G. Soundararajan et al. — [Extending SSD Lifetimes with Disk-Based Write Caches](https://www.usenix.org/conference/fast-10/extending-ssd-lifetimes-disk-based-write-caches) (2010).
+- Y. Oh — [SSD RAID as Cache (SRC) with Log-structured Approach for Performance and Reliability](https://ysoh.files.wordpress.com/2009/05/dm-src-ibm.pdf) (2014).
 
 ## Award
-Awarded by Japanese OSS Encouragement Award. Thanks!
+
+dm-writeboost received the Japanese OSS Encouragement Award. Thank you for your support!
 
 ## License
+
 ```
-Copyright (C) 2012-2025 Akira Hayakawa <ruby.wktk@gmail.com>
+Copyright (C) 2012-2026 Akira Hayakawa <ruby.wktk@gmail.com>
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -78,5 +97,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 ```
 
 ## Developer Info
-Akira Hayakawa (@akiradeveloper)  
-e-mail: ruby.wktk@gmail.com
+
+Akira Hayakawa ([@akiradeveloper](https://github.com/akiradeveloper))
+
+Email: ruby.wktk@gmail.com
diff --git a/src/dkms.conf b/src/dkms.conf
@@ -1,5 +1,5 @@
 PACKAGE_NAME="dm-writeboost"
-PACKAGE_VERSION="2.2.19"
+PACKAGE_VERSION="2.2.20"
 
 # Minimum supported Linux kernel version
 BUILD_EXCLUSIVE_KERNEL_MIN="4.18"

diff --git a/src/dm-writeboost-daemon.c b/src/dm-writeboost-daemon.c
@@ -1,6 +1,6 @@
 /*
  * This file is part of dm-writeboost
- * Copyright (C) 2012-2025 Akira Hayakawa <ruby.wktk@gmail.com>
+ * Copyright (C) 2012-2026 Akira Hayakawa <ruby.wktk@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by

diff --git a/src/dm-writeboost-daemon.h b/src/dm-writeboost-daemon.h
@@ -1,6 +1,6 @@
 /*
  * This file is part of dm-writeboost
- * Copyright (C) 2012-2025 Akira Hayakawa <ruby.wktk@gmail.com>
+ * Copyright (C) 2012-2026 Akira Hayakawa <ruby.wktk@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by

diff --git a/src/dm-writeboost-metadata.c b/src/dm-writeboost-metadata.c
@@ -1,6 +1,6 @@
 /*
  * This file is part of dm-writeboost
- * Copyright (C) 2012-2025 Akira Hayakawa <ruby.wktk@gmail.com>
+ * Copyright (C) 2012-2026 Akira Hayakawa <ruby.wktk@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by

diff --git a/src/dm-writeboost-metadata.h b/src/dm-writeboost-metadata.h
@@ -1,6 +1,6 @@
 /*
  * This file is part of dm-writeboost
- * Copyright (C) 2012-2025 Akira Hayakawa <ruby.wktk@gmail.com>
+ * Copyright (C) 2012-2026 Akira Hayakawa <ruby.wktk@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by

diff --git a/src/dm-writeboost-target.c b/src/dm-writeboost-target.c
@@ -3,7 +3,7 @@
  * Log-structured Caching for Linux
  *
  * This file is part of dm-writeboost
- * Copyright (C) 2012-2025 Akira Hayakawa <ruby.wktk@gmail.com>
+ * Copyright (C) 2012-2026 Akira Hayakawa <ruby.wktk@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -1948,7 +1948,7 @@ static void writeboost_status(struct dm_target *ti, status_type_t type,
 
 static struct target_type writeboost_target = {
 	.name = "writeboost",
-	.version = {2, 2, 19},
+	.version = {2, 2, 20},
 	.module = THIS_MODULE,
 	.map = writeboost_map,
 	.end_io = writeboost_end_io,

diff --git a/src/dm-writeboost.h b/src/dm-writeboost.h
@@ -1,6 +1,6 @@
 /*
  * This file is part of dm-writeboost
- * Copyright (C) 2012-2025 Akira Hayakawa <ruby.wktk@gmail.com>
+ * Copyright (C) 2012-2026 Akira Hayakawa <ruby.wktk@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by