From: Dan Williams <dan.j.williams@intel.com>
Date: Tue, 8 Nov 2011 05:22:06 +0000 (+1100)
Subject: md/raid5: STRIPE_ACTIVE has lock semantics, add barriers
X-Git-Tag: v3.1.1~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9851882600e7ad611093c661e785572bc8161493;p=thirdparty%2Fkernel%2Fstable.git

md/raid5: STRIPE_ACTIVE has lock semantics, add barriers

commit 257a4b42af7586fab4eaec7f04e6896b86551843 upstream.

All updates that occur under STRIPE_ACTIVE should be globally visible
when STRIPE_ACTIVE clears.  test_and_set_bit() implies a barrier, but
clear_bit() does not.

This is suitable for 3.1-stable.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 06c82c1bc2ccc..b6200c3935ca3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3116,7 +3116,7 @@ static void handle_stripe(struct stripe_head *sh)
 	struct r5dev *pdev, *qdev;
 
 	clear_bit(STRIPE_HANDLE, &sh->state);
-	if (test_and_set_bit(STRIPE_ACTIVE, &sh->state)) {
+	if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
 		/* already being handled, ensure it gets handled
 		 * again when current action finishes */
 		set_bit(STRIPE_HANDLE, &sh->state);
@@ -3381,7 +3381,7 @@ finish:
 
 	return_io(s.return_bi);
 
-	clear_bit(STRIPE_ACTIVE, &sh->state);
+	clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
 }
 
 static void raid5_activate_delayed(raid5_conf_t *conf)