Hi Neil,
below is a bit less-ugly version of the patch.
Thanks,
Alex.
>From 05cf800d623bf558c99d542cf8bf083c85b7e5d5 Mon Sep 17 00:00:00 2001
From: Alex Lyakas <alex@xxxxxxxxxxxxxxxxx>
Date: Thu, 13 Sep 2012 18:55:00 +0300
Subject: [PATCH] When RAID5 is dirty, force reconstruct-write instead of
read-modify-write.
Signed-off-by: Alex Lyakas <alex@xxxxxxxxxxxxxxxxx>
Signed-off-by: Yair Hershko <yair@xxxxxxxxxxxxxxxxx>
diff --git a/ubuntu_kmodules/Ubuntu-3.2.0-25.40/drivers/md/raid5.c
b/ubuntu_kmodules/Ubuntu-3.2.0-25.40/drivers/md/raid5.c
index 5332202..0702785 100644
--- a/ubuntu_kmodules/Ubuntu-3.2.0-25.40/drivers/md/raid5.c
+++ b/ubuntu_kmodules/Ubuntu-3.2.0-25.40/drivers/md/raid5.c
@@ -2555,12 +2555,36 @@ static void handle_stripe_dirtying(struct r5conf *conf,
int disks)
{
int rmw = 0, rcw = 0, i;
- if (conf->max_degraded == 2) {
- /* RAID6 requires 'rcw' in current implementation
- * Calculate the real rcw later - for now fake it
+ sector_t recovery_cp = conf->mddev->recovery_cp;
+ unsigned long recovery = conf->mddev->recovery;
+ int needed = test_bit(MD_RECOVERY_NEEDED, &recovery);
+ int resyncing = test_bit(MD_RECOVERY_SYNC, &recovery) &&
+ !test_bit(MD_RECOVERY_REQUESTED, &recovery) &&
+ !test_bit(MD_RECOVERY_CHECK, &recovery);
+ int transitional = test_bit(MD_RECOVERY_RUNNING, &recovery) &&
+ !test_bit(MD_RECOVERY_SYNC, &recovery) &&
+ !test_bit(MD_RECOVERY_RECOVER, &recovery) &&
+ !test_bit(MD_RECOVERY_DONE, &recovery) &&
+ !test_bit(MD_RECOVERY_RESHAPE, &recovery);
+
+ /* RAID6 requires 'rcw' in current implementation.
+ * Otherwise, attempt to check whether resync is now happening
+ * or should start.
+ * If yes, then the array is dirty (after unclean shutdown or
+ * initial creation), so parity in some stripes might be inconsistent.
+ * In this case, we need to always do reconstruct-write, to ensure
+ * that in case of drive failure or read-error correction, we
+ * generate correct data from the parity.
+ */
+ if (conf->max_degraded == 2 ||
+ (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
+ (needed || resyncing || transitional))) {
+ /* Calculate the real rcw later - for now fake it
* look like rcw is cheaper
*/
rcw = 1; rmw = 2;
+ pr_debug("force RCW max_degraded=%u, recovery_cp=%lu
sh->sector=%lu recovery=0x%lx\n",
+ conf->max_degraded, recovery_cp, sh->sector, recovery);
} else for (i = disks; i--; ) {
/* would I have to read this buffer for read_modify_write */
struct r5dev *dev = &sh->dev[i];
--
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