[PATCH] md/raid1: always set MD_RECOVERY_INTR flag in raid1 error handler to avoid potential data corruption

[jiao hui <jiaohui@bwstor.com.cn>]

From 1fdbfb8552c00af55d11d7a63cdafbdf1749ff63 Mon Sep 17 00:00:00 2001
From: Jiao Hui <simonjiaoh@gmail.com>
Date: Mon, 28 Jul 2014 11:57:20 +0800
Subject: [PATCH] md/raid1: always set MD_RECOVERY_INTR flag in raid1 error handler to avoid potential data corruption

    In the recovery of raid1 with bitmap, if a bitmap bit has a NEEDED or RESYNC flag,
    actual resync io will happen. The sync_thread check each rdev, if any rdev is missing
    or has a FAULTY flag, the array is still_degraded, then the bitmap bit NEEDED flag
    not cleared. Otherwise, we cleared NEEDED flag and set RESYNC flag. The RESYNC flag cleared
    in bitmap_cond_end_sync or bitmap_close_sync.

    If the only disk which is being recovered fails again when raid1 recovery is in progress.
    The resync_thread can't find a non-In_sync disk to write, then the remaining recovery skipped.
    RAID1 error handler only set MD_RECOVERY_INTR flag when a In_sync disk fails. But the disk
    being reocvered is non-In_sync, then md_do_sync can't got the INTR singal to break, and the
    mddev->curr_resync is uptodated to max_sectors (mddev->dev_sectors). When raid1 personality
    tries to finish resync process, no bitmap bit with RESYNC flag can set back to NEEDED flag,
    and bitmap_close_sync clear the RESYNC flag. When the disk is added back, the area from
    the offset of last recovery to the end of bitmap-chunk is skipped by resync_thread forever.
    
    Signed-off-by: JiaoHui <jiaohui@bwstor.com.cn>

---
 drivers/md/raid1.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index aacf6bf..51d06eb 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1391,16 +1391,16 @@ static void error(struct mddev *mddev, struct md_rdev *rdev)
 		return;
 	}
 	set_bit(Blocked, &rdev->flags);
+	/*
+	 * if recovery is running, make sure it aborts.
+	 */
+	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
 	if (test_and_clear_bit(In_sync, &rdev->flags)) {
 		unsigned long flags;
 		spin_lock_irqsave(&conf->device_lock, flags);
 		mddev->degraded++;
 		set_bit(Faulty, &rdev->flags);
 		spin_unlock_irqrestore(&conf->device_lock, flags);
-		/*
-		 * if recovery is running, make sure it aborts.
-		 */
-		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
 	} else
 		set_bit(Faulty, &rdev->flags);
 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
-- 
1.8.3.1