[PATCH 3.14 219/238] md/raid1: count resync requests in nr_pending.

From: Greg Kroah-Hartman
Date: Fri Oct 03 2014 - 19:05:19 EST


3.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: NeilBrown <neilb@xxxxxxx>

commit 34e97f170149bfa14979581c4c748bc9b4b79d5b upstream.

Both normal IO and resync IO can be retried with reschedule_retry()
and so be counted into ->nr_queued, but only normal IO gets counted in
->nr_pending.

Before the recent improvement to RAID1 resync there could only
possibly have been one or the other on the queue. When handling a
read failure it could only be normal IO. So when handle_read_error()
called freeze_array() the fact that freeze_array only compares
->nr_queued against ->nr_pending was safe.

But now that these two types can interleave, we can have both normal
and resync IO requests queued, so we need to count them both in
nr_pending.

This error can lead to freeze_array() hanging if there is a read
error, so it is suitable for -stable.

Fixes: 79ef3a8aa1cb1523cc231c9a90a278333c21f761
Reported-by: Brassow Jonathan <jbrassow@xxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/md/raid1.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -856,6 +856,7 @@ static void raise_barrier(struct r1conf
conf->next_resync + RESYNC_SECTORS),
conf->resync_lock);

+ conf->nr_pending++;
spin_unlock_irq(&conf->resync_lock);
}

@@ -865,6 +866,7 @@ static void lower_barrier(struct r1conf
BUG_ON(conf->barrier <= 0);
spin_lock_irqsave(&conf->resync_lock, flags);
conf->barrier--;
+ conf->nr_pending--;
spin_unlock_irqrestore(&conf->resync_lock, flags);
wake_up(&conf->wait_barrier);
}


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