Add RELEASES.md file

Document the project's policy regarding publishing and maintaining
official OpenZFS releases.

Reviewed-by: Tony Hutter <[email protected]>
Reviewed-by: Matthew Ahrens <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #11821

Makefile.am

@@ -26,8 +26,8 @@ endif
 AUTOMAKE_OPTIONS = foreign
 EXTRA_DIST  = autogen.sh copy-builtin
 EXTRA_DIST += config/config.awk config/rpm.am config/deb.am config/tgz.am
-EXTRA_DIST += META AUTHORS COPYRIGHT LICENSE NEWS NOTICE README.md
-EXTRA_DIST += CODE_OF_CONDUCT.md
+EXTRA_DIST += AUTHORS CODE_OF_CONDUCT.md COPYRIGHT LICENSE META NEWS NOTICE
+EXTRA_DIST += README.md RELEASES.md
 EXTRA_DIST += module/lua/README.zfs module/os/linux/spl/README.md
 
 # Include all the extra licensing information for modules

RELEASES.md

@@ -0,0 +1,37 @@
+OpenZFS uses the MAJOR.MINOR.PATCH versioning scheme described here:
+
+  * MAJOR - Incremented at the discretion of the OpenZFS developers to indicate
+    a particularly noteworthy feature or change. An increase in MAJOR number
+    does not indicate any incompatible on-disk format change. The ability
+    to import a ZFS pool is controlled by the feature flags enabled on the
+    pool and the feature flags supported by the installed OpenZFS version.
+    Increasing the MAJOR version is expected to be an infrequent occurrence.
+
+  * MINOR - Incremented to indicate new functionality such as a new feature
+    flag, pool/dataset property, zfs/zpool sub-command, new user/kernel
+    interface, etc. MINOR releases may introduce incompatible changes to the
+    user space library APIs (libzfs.so). Existing user/kernel interfaces are
+    considered to be stable to maximize compatibility between OpenZFS releases.
+    Additions to the user/kernel interface are backwards compatible.
+
+  * PATCH - Incremented when applying documentation updates, important bug
+    fixes, minor performance improvements, and kernel compatibility patches.
+    The user space library APIs and user/kernel interface are considered to
+    be stable. PATCH releases for a MAJOR.MINOR are published as needed.
+
+Two release branches are maintained for OpenZFS, they are:
+
+  * OpenZFS LTS - A designated MAJOR.MINOR release with periodic PATCH
+    releases that incorporate important changes backported from newer OpenZFS
+    releases. This branch is intended for use in environments using an
+    LTS, enterprise, or similarly managed kernel (RHEL, Ubuntu LTS, Debian).
+    Minor changes to support these distribution kernels will be applied as
+    needed. New kernel versions released after the OpenZFS LTS release are
+    not supported. LTS releases will receive patches for at least 2 years.
+    The current LTS release is OpenZFS 2.1.
+
+  * OpenZFS current - Tracks the newest MAJOR.MINOR release. This branch
+    includes support for the latest OpenZFS features and recently releases
+    kernels.  When a new MINOR release is tagged the previous MINOR release
+    will no longer be maintained (unless it is an LTS release). New MINOR
+    releases are planned to occur roughly annually.