md/raid10: decrement correct pending counter when writing to replacement.

commit 884162df2aadd7414bef4935e1a54976fd4e3988 upstream.

When a write to a replacement device completes, we carefully
and correctly found the rdev that the write actually went to
and the blithely called rdev_dec_pending on the primary rdev,
even if this write was to the replacement.

This means that any writes to an array while a replacement
was ongoing would cause the nr_pending count for the primary
device to go negative, so it could never be removed.

This bug has been present since replacement was introduced in
3.3, so it is suitable for any -stable kernel since then.

Reported-by: "George Spelvin" <linux@horizon.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index a48c215f1262e74246ea49ef25aa6f5892997034..3b636b874c9b1322e4aa3435a2791fc00bbfbedd 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -499,7 +499,7 @@ static void raid10_end_write_request(struct bio *bio, int error)
         */
        one_write_done(r10_bio);
        if (dec_rdev)
-               rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
+               rdev_dec_pending(rdev, conf->mddev);
 }
 
 /*