zfs_2_1: remove

With the release of 2.3.0-rc, we know that 2.3.0 will be coming sometime
soon. Per the [ZFS release policy][1], only the current and previous
releases are expected to be supported, so 2.1.x will become unsupported.
Unfortunately upstream does not have any specific timelines, so we do
not know when it will become unsupported, but when it does we will
likely backport the removal. As such, begin warning of imminent removal.

[1]: https://github.com/openzfs/zfs/blob/6187b194349c5a728c9df8c6842f1866d5c9782a/RELEASES.md

ci/foo.sh

@@ -0,0 +1,85 @@
+# Filtering error messages we don't like
+nixf_wrapper(){
+  nixf-tidy --variable-lookup < "$1" | jq -r '
+    [
+      "sema-escaping-with"
+    ]
+    as $ignored_errors|[.[]|select(.sname as $s|$ignored_errors|index($s)|not)]
+  '
+}
+
+failedFiles=()
+
+# Don't report errors to file overview
+# to avoid duplicates when editing title and description
+if [[ "______" ]]; then
+  DONT_REPORT_ERROR=1
+else
+  DONT_REPORT_ERROR=
+fi
+# TODO: Make this more parallel
+
+# Loop through all Nix files touched by the PR
+while readarray -d '' -n 2 entry && (( ${#entry[@]} != 0 )); do
+  type=${entry[0]}
+  file=${entry[1]}
+  case $type in
+    A*)
+      source=""
+      dest=$file
+      ;;
+    M*)
+      source=$file
+      dest=$file
+      ;;
+    C*|R*)
+      source=$file
+      read -r -d '' dest
+      ;;
+    *)
+      echo "Ignoring file $file with type $type"
+      continue
+  esac
+
+  if [[ -n "$source" ]] && [[ "$(nixf_wrapper ______/"$source")" != '[]' ]] 2>/dev/null; then
+    echo "Ignoring file $file because it doesn't pass nixf-tidy in the base commit"
+    echo # insert blank line
+  else
+    nixf_report="$(nixf_wrapper "$dest")"
+    if [[ "$nixf_report" != '[]' ]]; then
+      echo "$dest doesn't pass nixf-tidy. Reported by nixf-tidy:"
+      errors=$(echo "$nixf_report" | jq -r --arg dest "$dest" '
+        def getLCur: "line=" + (.line+1|tostring) + ",col=" + (.column|tostring);
+        def getRCur: "endLine=" + (.line+1|tostring) + ",endColumn=" + (.column|tostring);
+        def getRange: "file=\($dest)," + (.lCur|getLCur) + "," + (.rCur|getRCur);
+        def getBody: . as $top|(.range|getRange) + ",title="+ .sname + "::" +
+          (.message|sub("{}" ; ($top.args.[]|tostring)));
+        def getNote: "\n::notice " + (.|getBody);
+        def getMessage: "::error " + (.|getBody) + (if (.notes|length)>0 then
+          ([.notes.[]|getNote]|add) else "" end);
+        .[]|getMessage
+      ')
+      if [[ -z "$DONT_REPORT_ERROR" ]]; then
+        echo "$errors"
+      else
+        # just print in plain text
+        echo "$errors" | sed 's/^:://'
+        echo # add one empty line
+      fi
+      failedFiles+=("$dest")
+    fi
+  fi
+done < <(git diff -z --name-status ______ -- '*.nix')
+
+if [[ -n "$DONT_REPORT_ERROR" ]]; then
+  echo "Edited the PR but didn't change the base branch, only the description/title."
+  echo "Not reporting errors again to avoid duplication."
+  echo # add one empty line
+fi
+
+if (( "${#failedFiles[@]}" > 0 )); then
+  echo "Some new/changed Nix files don't pass nixf-tidy."
+  echo "See ______/files for reported errors."
+  echo "If you believe this is a false positive, ping @Aleksanaa and @inclyc in this PR."
+  exit 1
+fi

nixos/tests/zfs.nix

@@ -191,12 +191,6 @@ let
 
 in {
 
-  # maintainer: @raitobezarius
-  series_2_1 = makeZfsTest {
-    zfsPackage = pkgs.zfs_2_1;
-    kernelPackages = pkgs.linuxPackages;
-  };
-
   series_2_2 = makeZfsTest {
     zfsPackage = pkgs.zfs_2_2;
     kernelPackages = pkgs.linuxPackages;

pkgs/top-level/all-packages.nix

@@ -12924,17 +12924,13 @@ with pkgs;
 
   inherit
     ({
-      zfs_2_1 = callPackage ../os-specific/linux/zfs/2_1.nix {
-        configFile = "user";
-      };
       zfs_2_2 = callPackage ../os-specific/linux/zfs/2_2.nix {
         configFile = "user";
       };
       zfs_unstable = callPackage ../os-specific/linux/zfs/unstable.nix {
         configFile = "user";
       };
     })
-    zfs_2_1
     zfs_2_2
     zfs_unstable;
   zfs = zfs_2_2;

pkgs/top-level/linux-kernels.nix

@@ -578,10 +578,6 @@ in {
 
     zenpower = callPackage ../os-specific/linux/zenpower { };
 
-    zfs_2_1 = callPackage ../os-specific/linux/zfs/2_1.nix {
-      configFile = "kernel";
-      inherit pkgs kernel;
-    };
     zfs_2_2 = callPackage ../os-specific/linux/zfs/2_2.nix {
       configFile = "kernel";
       inherit pkgs kernel;