fix(inputs.zfs): Support gathering metrics on zfs 2.2.0 and later (#14280)

plugins/inputs/zfs/README.md

@@ -223,6 +223,27 @@ For ZFS >= 2.1.x the format has changed significantly:
   - nunlinks (integer, count)
   - nunlinked (integer, count)
 
+For ZFS >= 2.2.x the following additional fields are available:
+
+- additional fields for ZFS > 2.2.x
+  - zil_commit_count (integer, count)
+  - zil_commit_writer_count (integer, count)
+  - zil_itx_count (integer, count)
+  - zil_itx_indirect_count (integer, count)
+  - zil_itx_indirect_bytes (integer, bytes)
+  - zil_itx_copied_count (integer, count)
+  - zil_itx_copied_bytes (integer, bytes)
+  - zil_itx_needcopy_count (integer, count)
+  - zil_itx_needcopy_bytes (integer, bytes)
+  - zil_itx_metaslab_normal_count (integer, count)
+  - zil_itx_metaslab_normal_bytes (integer, bytes)
+  - zil_itx_metaslab_normal_write (integer, bytes)
+  - zil_itx_metaslab_normal_alloc (integer, bytes)
+  - zil_itx_metaslab_slog_count (integer, count)
+  - zil_itx_metaslab_slog_bytes (integer, bytes)
+  - zil_itx_metaslab_slog_write (integer, bytes)
+  - zil_itx_metaslab_slog_alloc (integer, bytes)
+
 On FreeBSD:
 
 - zfs_pool
@@ -391,6 +412,7 @@ memory is too low)
 
 ### ZIL (Linux Only)
 
-note: ZIL measurements are system-wide, neither per-pool nor per-dataset
+note: `zil` measurements in `kstatMetrics` are system-wide, in `poolMetrics`
+they are pool-wide
 
 `zil_commit_count` counts when ZFS transactions are committed to a ZIL

plugins/inputs/zfs/zfs_linux.go

@@ -84,7 +84,7 @@ func getTags(pools []poolInfo) map[string]string {
 }
 
 func gather(lines []string, fileLines int) ([]string, []string, error) {
-	if len(lines) != fileLines {
+	if len(lines) < fileLines {
 		return nil, nil, errors.New("expected lines in kstat does not match")
 	}
 
@@ -172,7 +172,7 @@ func gatherPoolStats(pool poolInfo, acc telegraf.Accumulator) error {
 	}
 
 	if gatherErr != nil {
-		return err
+		return gatherErr
 	}
 
 	acc.AddFields("zfs_pool", fields, tags)

plugins/inputs/zfs/zfs_linux_test.go

@@ -130,6 +130,33 @@ nread                           4    1884160
 nunlinks                        4    14148
 nunlinked                       4    14147
 `
+const objsetV22Contents = `36 1 0x01 7 2160 5214787391 74985931356512
+name                            type data
+dataset_name                    7    HOMEV22
+writes                          4    978
+nwritten                        4    6450688
+reads                           4    22
+nread                           4    1884160
+nunlinks                        4    14148
+nunlinked                       4    14147
+zil_commit_count                4    1
+zil_commit_writer_count         4    2
+zil_itx_count                   4    3
+zil_itx_indirect_count          4    4
+zil_itx_indirect_bytes          4    5
+zil_itx_copied_count            4    6
+zil_itx_copied_bytes            4    7
+zil_itx_needcopy_count          4    8
+zil_itx_needcopy_bytes          4    9
+zil_itx_metaslab_normal_count   4    10
+zil_itx_metaslab_normal_bytes   4    11
+zil_itx_metaslab_normal_write   4    12
+zil_itx_metaslab_normal_alloc   4    13
+zil_itx_metaslab_slog_count     4    14
+zil_itx_metaslab_slog_bytes     4    15
+zil_itx_metaslab_slog_write     4    16
+zil_itx_metaslab_slog_alloc     4    17
+`
 const zilContents = `7 1 0x01 14 672 34118481334 437444452158445
 name                            type data
 zil_commit_count                4    77
@@ -235,6 +262,8 @@ func TestZfsPoolMetrics(t *testing.T) {
 
 	err = os.WriteFile(testKstatPath+"/HOME/objset-0x20a", []byte(objsetContents), 0640)
 	require.NoError(t, err)
+	err = os.WriteFile(testKstatPath+"/HOME/objset-0x20b", []byte(objsetV22Contents), 0640)
+	require.NoError(t, err)
 
 	acc.Metrics = nil
 
@@ -242,9 +271,12 @@ func TestZfsPoolMetrics(t *testing.T) {
 	require.NoError(t, err)
 
 	tags["dataset"] = "HOME"
-
 	poolMetrics = getPoolMetricsNewFormat()
 	acc.AssertContainsTaggedFields(t, "zfs_pool", poolMetrics, tags)
+
+	tags["dataset"] = "HOMEV22"
+	poolMetrics = getPoolMetricsNewFormatV22()
+	acc.AssertContainsTaggedFields(t, "zfs_pool", poolMetrics, tags)
 }
 
 func TestZfsGeneratesMetrics(t *testing.T) {
@@ -554,3 +586,31 @@ func getPoolMetricsNewFormat() map[string]interface{} {
 		"writes":    int64(978),
 	}
 }
+
+func getPoolMetricsNewFormatV22() map[string]interface{} {
+	return map[string]interface{}{
+		"nread":                         int64(1884160),
+		"nunlinked":                     int64(14147),
+		"nunlinks":                      int64(14148),
+		"nwritten":                      int64(6450688),
+		"reads":                         int64(22),
+		"writes":                        int64(978),
+		"zil_commit_count":              int64(1),
+		"zil_commit_writer_count":       int64(2),
+		"zil_itx_count":                 int64(3),
+		"zil_itx_indirect_count":        int64(4),
+		"zil_itx_indirect_bytes":        int64(5),
+		"zil_itx_copied_count":          int64(6),
+		"zil_itx_copied_bytes":          int64(7),
+		"zil_itx_needcopy_count":        int64(8),
+		"zil_itx_needcopy_bytes":        int64(9),
+		"zil_itx_metaslab_normal_count": int64(10),
+		"zil_itx_metaslab_normal_bytes": int64(11),
+		"zil_itx_metaslab_normal_write": int64(12),
+		"zil_itx_metaslab_normal_alloc": int64(13),
+		"zil_itx_metaslab_slog_count":   int64(14),
+		"zil_itx_metaslab_slog_bytes":   int64(15),
+		"zil_itx_metaslab_slog_write":   int64(16),
+		"zil_itx_metaslab_slog_alloc":   int64(17),
+	}
+}