From e2ea60907ca2b30e1ac5744d3e17dff16ed910ce Mon Sep 17 00:00:00 2001
From: Victor Lowther <victor.lowther@gmail.com>
Date: Wed, 9 Jun 2010 05:23:57 -0500
Subject: Refuse to change sata link pm states on kernels < 2.6.33

Kernels earlier then 2.6.33 have a bug that can cause filesystem corruption
due to the upper layers aborting a transaction instead of retrying it if the
sata link glitches out momentarily during a power state transition.
---
 pm/power.d/sata_alpm | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pm/power.d/sata_alpm b/pm/power.d/sata_alpm
index 82c8201..6391e09 100644
--- a/pm/power.d/sata_alpm
+++ b/pm/power.d/sata_alpm
@@ -22,6 +22,10 @@ EOF
 }
 
 set_sata_alpm() {
+    # see kernel commit 6013efd8860bf15c1f86f365332642cfe557152f
+    kv="$(uname -r)"
+    [ "$kv" ] || exit $NA  #for paranoia's sake
+    [ "${kv%-*}" \< "2.6.33" ] && exit $NA  # avoid fs corruption
     for f in /sys/class/scsi_host/host*/link_power_management_policy; do
 	[ -w "$f" ] || continue
 	echo "$1" > "$f"
-- 
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