[3.8.y.z extended stable] Patch "raid5: avoid finding "discard" stripe" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    raid5: avoid finding "discard" stripe

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.13.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 67cd3bc6429c9507356f39b9ac0c402b00998ac8 Mon Sep 17 00:00:00 2001
From: Shaohua Li <shli at kernel.org>
Date: Sat, 19 Oct 2013 14:51:42 +0800
Subject: raid5: avoid finding "discard" stripe

commit d47648fcf0611812286f68131b40251c6fa54f5e upstream.

SCSI discard will damage discard stripe bio setting, eg, some fields are
changed. If the stripe is reused very soon, we have wrong bios setting. We
remove discard stripe from hash list, so next time the strip will be fully
initialized.

Suitable for backport to 3.7+.

Signed-off-by: Shaohua Li <shli at fusionio.com>
Signed-off-by: NeilBrown <neilb at suse.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/md/raid5.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7ace380..51887b3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2841,6 +2841,14 @@ static void handle_stripe_clean_event(struct r5conf *conf,
 		}
 		/* now that discard is done we can proceed with any sync */
 		clear_bit(STRIPE_DISCARD, &sh->state);
+		/*
+		 * SCSI discard will change some bio fields and the stripe has
+		 * no updated data, so remove it from hash list and the stripe
+		 * will be reinitialized
+		 */
+		spin_lock_irq(&conf->device_lock);
+		remove_hash(sh);
+		spin_unlock_irq(&conf->device_lock);
 		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
 			set_bit(STRIPE_HANDLE, &sh->state);

--
1.8.1.2