zfs: add migration path for new crypto format

fixes #34559

nixos/modules/tasks/filesystems/zfs.nix

···
 
   kernel = config.boot.kernelPackages;
 
-  packages = if config.boot.zfs.enableUnstable then {
+  packages = if config.boot.zfs.enableLegacyCrypto then {
+    spl = kernel.splLegacyCrypto;
+    zfs = kernel.zfsLegacyCrypto;
+    zfsUser = pkgs.zfsLegacyCrypto;
+  } else if config.boot.zfs.enableUnstable then {
     spl = kernel.splUnstable;
     zfs = kernel.zfsUnstable;
     zfsUser = pkgs.zfsUnstable;
···
           version will have already passed an extensive test suite, but it is
           more likely to hit an undiscovered bug compared to running a released
           version of ZFS on Linux.
+          '';
+      };
+
+      enableLegacyCrypto = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Enabling this option will allow you to continue to use the old format for
+          encrypted datasets. With the inclusion of stability patches the format of
+          encrypted datasets has changed. They can still be access and mounted but
+          in read-only mode mounted. It is highly recommended to convert them to
+          the new format.
+
+          This option is only for convenience to people that cannot convert their
+          datasets to the new format yet and it will be removed in due time.
+
+          For migration strategies from old format to this new one, check the Wiki:
+          https://nixos.wiki/wiki/NixOS_on_ZFS#Encrypted_Dataset_Format_Change
+
+          See https://github.com/zfsonlinux/zfs/pull/6864 for more details about
+          the stability patches.
           '';
       };
 

pkgs/os-specific/linux/spl/default.nix

···
     };
 
     splUnstable = common {
-      version = "2017-12-21";
-      rev = "c9821f1ccc647dfbd506f381b736c664d862d126";
-      sha256 = "08r6sa36jaj6n54ap18npm6w85v5yn3x8ljg792h37f49b8kir6c";
+      version = "2018-01-24";
+      rev = "23602fdb39e1254c669707ec9d2d0e6bcdbf1771";
+      sha256 = "09py2dwj77f6s2qcnkwdslg5nxb3hq2bq39zpxpm6msqyifhl69h";
+    };
+
+    splLegacyCrypto = common {
+      version = "2018-01-24";
+      rev = "23602fdb39e1254c669707ec9d2d0e6bcdbf1771";
+      sha256 = "09py2dwj77f6s2qcnkwdslg5nxb3hq2bq39zpxpm6msqyifhl69h";
     };
 }

pkgs/os-specific/linux/zfs/default.nix

···
 , zlib, libuuid, python, attr, openssl
 
 # Kernel dependencies
-, kernel ? null, spl ? null, splUnstable ? null
+, kernel ? null, spl ? null, splUnstable ? null, splLegacyCrypto ? null
 }:
 
 with stdenv.lib;
···
     , spl
     , rev ? "zfs-${version}"
     , isUnstable ? false
+    , isLegacyCrypto ? false
     , incompatibleKernelVersion ? null } @ args:
     if buildKernel &&
       (incompatibleKernelVersion != null) &&
···
       buildInputs =
            optionals buildKernel [ spl ]
         ++ optionals buildUser [ zlib libuuid python attr ]
-        ++ optionals (buildUser && isUnstable) [ openssl ];
+        ++ optionals (buildUser && (isUnstable || isLegacyCrypto)) [ openssl ];
 
       # for zdb to get the rpath to libgcc_s, needed for pthread_cancel to work
       NIX_CFLAGS_LINK = "-lgcc_s";
···
     incompatibleKernelVersion = null;
 
     # this package should point to a version / git revision compatible with the latest kernel release
-    version = "2018-01-10";
+    version = "2018-02-02";
 
-    rev = "1d53657bf561564162e2ad6449f80fa0140f1dd6";
-    sha256 = "0ibkhfz06cypgl2c869dzdbdx2i3m8ywwdmnzscv0cin5gm31vhx";
+    rev = "fbd42542686af053f0d162ec4630ffd4fff1cc30";
+    sha256 = "0qzkwnnk7kz1hwvcaqlpzi5yspfhhmd2alklc07k056ddzbx52qb";
     isUnstable = true;
 
     extraPatches = [
       (fetchpatch {
-        url = "https://github.com/Mic92/zfs/compare/ded8f06a3cfee...nixos-zfs-2017-09-12.patch";
-        sha256 = "033wf4jn0h0kp0h47ai98rywnkv5jwvf3xwym30phnaf8xxdx8aj";
+        url = "https://github.com/Mic92/zfs/compare/fbd42542686af053f0d162ec4630ffd4fff1cc30...nixos-zfs-2018-02-02.patch";
+        sha256 = "05wqwjm9648x60vkwxbp8l6z1q73r2a5l2ni28i2f4pla8s3ahln";
       })
     ];
 
     spl = splUnstable;
   };
+
+  zfsLegacyCrypto = common {
+    # comment/uncomment if breaking kernel versions are known
+    incompatibleKernelVersion = null;
+
+    # this package should point to a version / git revision compatible with the latest kernel release
+    version = "2018-02-01";
+
+    rev = "4c46b99d24a6e71b3c72462c11cb051d0930ad60";
+    sha256 = "011lcp2x44jgfzqqk2gjmyii1v7rxcprggv20prxa3c552drsx3c";
+    isUnstable = true;
+
+    extraPatches = [
+      (fetchpatch {
+        url = "https://github.com/Mic92/zfs/compare/4c46b99d24a6e71b3c72462c11cb051d0930ad60...nixos-zfs-2018-02-01.patch";
+        sha256 = "1gqmgqi39qhk5kbbvidh8f2xqq25vj58i9x0wjqvcx6a71qj49ch";
+      })
+    ];
+
+    spl = splLegacyCrypto;
+  };
+
 }

pkgs/top-level/all-packages.nix

···
     sch_cake = callPackage ../os-specific/linux/sch_cake { };
 
     inherit (callPackage ../os-specific/linux/spl {})
-      splStable splUnstable;
+      splStable splUnstable splLegacyCrypto;
 
     spl = splStable;
 
···
     inherit (callPackage ../os-specific/linux/zfs {
       configFile = "kernel";
       inherit kernel spl;
-     }) zfsStable zfsUnstable;
+     }) zfsStable zfsUnstable zfsLegacyCrypto;
 
      zfs = zfsStable;
   });
···
 
   inherit (callPackage ../os-specific/linux/zfs {
     configFile = "user";
-  }) zfsStable zfsUnstable;
+  }) zfsStable zfsUnstable zfsLegacyCrypto;
 
   zfs = zfsStable;