linux-kernel - [PATCH 4.19 079/220] md: allow metadata updates while suspending an array

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Date:   Fri, 22 Nov 2019 11:27:24 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jeff Mahoney <jeffm@...e.com>,
        NeilBrown <neilb@...e.com>, Shaohua Li <shli@...com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 079/220] md: allow metadata updates while suspending an array - fix

From: NeilBrown <neilb@...e.com>

[ Upstream commit 059421e041eb461fb2b3e81c9adaec18ef03ca3c ]

Commit 35bfc52187f6 ("md: allow metadata update while suspending.")
added support for allowing md_check_recovery() to still perform
metadata updates while the array is entering the 'suspended' state.
This is needed to allow the processes of entering the state to
complete.

Unfortunately, the patch doesn't really work.  The test for
"mddev->suspended" at the start of md_check_recovery() means that the
function doesn't try to do anything at all while entering suspend.

This patch moves the code of updating the metadata while suspending to
*before* the test on mddev->suspended.

Reported-by: Jeff Mahoney <jeffm@...e.com>
Fixes: 35bfc52187f6 ("md: allow metadata update while suspending.")
Signed-off-by: NeilBrown <neilb@...e.com>
Signed-off-by: Shaohua Li <shli@...com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/md/md.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index a8fbaa384e9ae..2fe4f93d1d7d4 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8778,6 +8778,18 @@ static void md_start_sync(struct work_struct *ws)
  */
 void md_check_recovery(struct mddev *mddev)
 {
+	if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags) && mddev->sb_flags) {
+		/* Write superblock - thread that called mddev_suspend()
+		 * holds reconfig_mutex for us.
+		 */
+		set_bit(MD_UPDATING_SB, &mddev->flags);
+		smp_mb__after_atomic();
+		if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags))
+			md_update_sb(mddev, 0);
+		clear_bit_unlock(MD_UPDATING_SB, &mddev->flags);
+		wake_up(&mddev->sb_wait);
+	}
+
 	if (mddev->suspended)
 		return;
 
@@ -8938,16 +8950,6 @@ void md_check_recovery(struct mddev *mddev)
 	unlock:
 		wake_up(&mddev->sb_wait);
 		mddev_unlock(mddev);
-	} else if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags) && mddev->sb_flags) {
-		/* Write superblock - thread that called mddev_suspend()
-		 * holds reconfig_mutex for us.
-		 */
-		set_bit(MD_UPDATING_SB, &mddev->flags);
-		smp_mb__after_atomic();
-		if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags))
-			md_update_sb(mddev, 0);
-		clear_bit_unlock(MD_UPDATING_SB, &mddev->flags);
-		wake_up(&mddev->sb_wait);
 	}
 }
 EXPORT_SYMBOL(md_check_recovery);
-- 
2.20.1