From a271a89c6e4773478b1c4f8213dfe8351ea66723 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 10 Jun 2020 16:07:57 -0400 Subject: [PATCH] dm mpath: take m->lock spinlock when testing QUEUE_IF_NO_PATH Fix multipath_end_io, multipath_end_io_bio and multipath_busy to take m->lock while testing if MPATHF_QUEUE_IF_NO_PATH bit is set. These are all slow-path cases when no paths are available so extra locking isn't a performance hit. Correctness matters most. Signed-off-by: Mike Snitzer --- drivers/md/dm-mpath.c | 52 ++++++++++++++++++++++++++++--------------- 1 file changed, 34 insertions(+), 18 deletions(-) diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index d7bb74bded8c..bf5175805b1d 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -1621,12 +1621,16 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone, if (pgpath) fail_path(pgpath); - if (atomic_read(&m->nr_valid_paths) == 0 && - !must_push_back_rq(m)) { - if (error == BLK_STS_IOERR) - dm_report_EIO(m); - /* complete with the original error */ - r = DM_ENDIO_DONE; + if (!atomic_read(&m->nr_valid_paths)) { + unsigned long flags; + spin_lock_irqsave(&m->lock, flags); + if (!must_push_back_rq(m)) { + if (error == BLK_STS_IOERR) + dm_report_EIO(m); + /* complete with the original error */ + r = DM_ENDIO_DONE; + } + spin_unlock_irqrestore(&m->lock, flags); } } @@ -1656,15 +1660,19 @@ static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone, if (pgpath) fail_path(pgpath); - if (atomic_read(&m->nr_valid_paths) == 0 && - !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) { - if (__must_push_back(m)) { - r = DM_ENDIO_REQUEUE; - } else { - dm_report_EIO(m); - *error = BLK_STS_IOERR; + if (!atomic_read(&m->nr_valid_paths)) { + spin_lock_irqsave(&m->lock, flags); + if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) { + if (__must_push_back(m)) { + r = DM_ENDIO_REQUEUE; + } else { + dm_report_EIO(m); + *error = BLK_STS_IOERR; + } + spin_unlock_irqrestore(&m->lock, flags); + goto done; } - goto done; + spin_unlock_irqrestore(&m->lock, flags); } spin_lock_irqsave(&m->lock, flags); @@ -1962,10 +1970,11 @@ static int multipath_prepare_ioctl(struct dm_target *ti, } } else { /* No path is available */ + r = -EIO; + spin_lock_irqsave(&m->lock, flags); if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) r = -ENOTCONN; - else - r = -EIO; + spin_unlock_irqrestore(&m->lock, flags); } if (r == -ENOTCONN) { @@ -2036,8 +2045,15 @@ static int multipath_busy(struct dm_target *ti) return true; /* no paths available, for blk-mq: rely on IO mapping to delay requeue */ - if (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) - return (m->queue_mode != DM_TYPE_REQUEST_BASED); + if (!atomic_read(&m->nr_valid_paths)) { + unsigned long flags; + spin_lock_irqsave(&m->lock, flags); + if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) { + spin_unlock_irqrestore(&m->lock, flags); + return (m->queue_mode != DM_TYPE_REQUEST_BASED); + } + spin_unlock_irqrestore(&m->lock, flags); + } /* Guess which priority_group will be used at next mapping time */ pg = READ_ONCE(m->current_pg); -- 2.20.1