3.2.72-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: NeilBrown <neilb@xxxxxxxx>
commit 423f04d63cf421ea436bcc5be02543d549ce4b28 upstream.
raid1_end_read_request() assumes that the In_sync bits are consistent
with the ->degaded count.
raid1_spare_active updates the In_sync bit before the ->degraded count
and so exposes an inconsistency, as does error()
So extend the spinlock in raid1_spare_active() and error() to hide those
inconsistencies.
This should probably be part of
Commit: 34cab6f42003 ("md/raid1: fix test for 'was read error from
last working device'.")
as it addresses the same issue. It fixes the same bug and should go
to -stable for same reasons.
Fixes: 76073054c95b ("md/raid1: clean up read_balance.")
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/md/raid1.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1208,6 +1208,7 @@ static void error(struct mddev *mddev, s
{
char b[BDEVNAME_SIZE];
struct r1conf *conf = mddev->private;
+ unsigned long flags;
/*
* If it is not operational, then we have already marked it as dead
@@ -1227,14 +1228,13 @@ static void error(struct mddev *mddev, s
return;
}
set_bit(Blocked, &rdev->flags);
+ spin_lock_irqsave(&conf->device_lock, flags);
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);
} else
set_bit(Faulty, &rdev->flags);
+ spin_unlock_irqrestore(&conf->device_lock, flags);
/*
* if recovery is running, make sure it aborts.
*/
@@ -1292,7 +1292,10 @@ static int raid1_spare_active(struct mdd
* Find all failed disks within the RAID1 configuration
* and mark them readable.
* Called under mddev lock, so rcu protection not needed.
+ * device_lock used to avoid races with raid1_end_read_request
+ * which expects 'In_sync' flags and ->degraded to be consistent.
*/
+ spin_lock_irqsave(&conf->device_lock, flags);
for (i = 0; i < conf->raid_disks; i++) {
struct md_rdev *rdev = conf->mirrors[i].rdev;
if (rdev
@@ -1302,7 +1305,6 @@ static int raid1_spare_active(struct mdd
sysfs_notify_dirent_safe(rdev->sysfs_state);
}
}
- spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded -= count;
spin_unlock_irqrestore(&conf->device_lock, flags);
--
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