From ccb185f0ea2a451ad7429b49f6fd172ccb0375f9 Mon Sep 17 00:00:00 2001
From: Sueun Cho <sueun.dev@gmail.com>
Date: Fri, 10 Jul 2026 10:35:29 -0500
Subject: [PATCH] fix(mdstat): parse (W), (J) and (R) component device flags

componentDeviceRE only captured ([SF]+), so the WriteMostly, Journal
and Replacement fields read from match[3] were always false, and a
flag following another one was dropped entirely - for sde1[4](W)(F)
the group matched nothing, losing Faulty as well. The kernel prints
each flag as its own parenthesis group, so capture a run of them.

Signed-off-by: Sueun Cho <sueun.dev@gmail.com>
---
 mdstat.go      |  2 +-
 mdstat_test.go | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/mdstat.go b/mdstat.go
index d66eeda8..90410179 100644
--- a/mdstat.go
+++ b/mdstat.go
@@ -27,7 +27,7 @@ var (
 	recoveryLinePctRE    = regexp.MustCompile(`= (.+)%`)
 	recoveryLineFinishRE = regexp.MustCompile(`finish=(.+)min`)
 	recoveryLineSpeedRE  = regexp.MustCompile(`speed=(.+)[A-Z]`)
-	componentDeviceRE    = regexp.MustCompile(`(.*)\[(\d+)\](\([SF]+\))?`)
+	componentDeviceRE    = regexp.MustCompile(`(.*)\[(\d+)\]((?:\([FJRSW]\))+)?`)
 	personalitiesPrefix  = "Personalities : "
 )
 
diff --git a/mdstat_test.go b/mdstat_test.go
index 4d94f93c..0a4bf539 100644
--- a/mdstat_test.go
+++ b/mdstat_test.go
@@ -369,3 +369,31 @@ md127 : active raid1 sdi2[0] sdj2[X]
 		}
 	}
 }
+func TestEvalComponentDevicesFlags(t *testing.T) {
+	// Flags as printed by the kernel, one per parenthesis group:
+	// https://github.com/torvalds/linux/blob/7ec462100ef9142344ddbf86f2c3008b97acddbe/drivers/md/md.c#L8376-L8392
+	devices, err := evalComponentDevices([]string{
+		"sda1[0](F)",
+		"sdb1[1](W)",
+		"sdc1[2](J)",
+		"sdd1[3](R)",
+		"sde1[4](W)(F)",
+		"sdg1[6](S)",
+		"sdf1[5]",
+	})
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+	want := []MDStatComponent{
+		{Name: "sda1", DescriptorIndex: 0, Faulty: true},
+		{Name: "sdb1", DescriptorIndex: 1, WriteMostly: true},
+		{Name: "sdc1", DescriptorIndex: 2, Journal: true},
+		{Name: "sdd1", DescriptorIndex: 3, Replacement: true},
+		{Name: "sde1", DescriptorIndex: 4, WriteMostly: true, Faulty: true},
+		{Name: "sdg1", DescriptorIndex: 6, Spare: true},
+		{Name: "sdf1", DescriptorIndex: 5},
+	}
+	if diff := cmp.Diff(want, devices); diff != "" {
+		t.Errorf("unexpected component devices (-want +got):\n%s", diff)
+	}
+}