From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaohua Li Subject: Re: [PATCH] md/raid1: avoid reusing a resync bio after error handling. Date: Mon, 10 Apr 2017 11:04:58 -0700 Message-ID: <20170410180458.5kco236g3gw2kcxm@kernel.org> References: <87bmsaguhe.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <87bmsaguhe.fsf@notabene.neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: Linux-RAID , Michael Wang List-Id: linux-raid.ids On Thu, Apr 06, 2017 at 12:06:37PM +1000, Neil Brown wrote: > > fix_sync_read_error() modifies a bio on a newly faulty > device by setting bi_end_io to end_sync_write. > This ensure that put_buf() will still call rdev_dec_pending() > as required, but makes sure that subsequent code in > fix_sync_read_error() doesn't try to read from the device. > > Unfortunately this interacts badly with sync_request_write() > which assumes that any bio with bi_end_io set to non-NULL > other than end_sync_read is safe to write to. > > As the device is now faulty it doesn't make sense to write. > As the bio was recently used for a read, it is "dirty" > and not suitable for immediate submission. > In particular, ->bi_next might be non-NULL, which will cause > generic_make_request() to complain. > > Break this interaction by refusing to write to devices > which are marked as Faulty. > > Reported-and-tested-by: Michael Wang > Fixes: 2e52d449bcec ("md/raid1: add failfast handling for reads.") > Cc: stable@vger.kernel.org (v4.10+) > Signed-off-by: NeilBrown Thanks, applied! > --- > drivers/md/raid1.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c > index a70283753a35..9c1b2231d2db 100644 > --- a/drivers/md/raid1.c > +++ b/drivers/md/raid1.c > @@ -2185,6 +2185,8 @@ static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio) > (i == r1_bio->read_disk || > !test_bit(MD_RECOVERY_SYNC, &mddev->recovery)))) > continue; > + if (test_bit(Faulty, &conf->mirrors[i].rdev->flags)) > + continue; > > bio_set_op_attrs(wbio, REQ_OP_WRITE, 0); > if (test_bit(FailFast, &conf->mirrors[i].rdev->flags)) > -- > 2.12.2 >