From 6bfe0b499082fd3950429017cd8ebf2a6c458aa5 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 30 Apr 2008 00:52:32 -0700 Subject: md: support blocking writes to an array on device failure Allows a userspace metadata handler to take action upon detecting a device failure. Based on an original patch by Neil Brown. Changes: -added blocked_wait waitqueue to rdev -don't qualify Blocked with Faulty always let userspace block writes -added md_wait_for_blocked_rdev to wait for the block device to be clear, if userspace misses the notification another one is sent every 5 seconds -set MD_RECOVERY_NEEDED after clearing "blocked" -kill DoBlock flag, just test mddev->external Signed-off-by: Dan Williams Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/raid10.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) (limited to 'drivers/md/raid10.c') diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 1e96aa3ff51..5938fa96292 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -790,6 +790,7 @@ static int make_request(struct request_queue *q, struct bio * bio) const int do_sync = bio_sync(bio); struct bio_list bl; unsigned long flags; + mdk_rdev_t *blocked_rdev; if (unlikely(bio_barrier(bio))) { bio_endio(bio, -EOPNOTSUPP); @@ -879,17 +880,23 @@ static int make_request(struct request_queue *q, struct bio * bio) /* * WRITE: */ - /* first select target devices under spinlock and + /* first select target devices under rcu_lock and * inc refcount on their rdev. Record them by setting * bios[x] to bio */ raid10_find_phys(conf, r10_bio); + retry_write: + blocked_rdev = 0; rcu_read_lock(); for (i = 0; i < conf->copies; i++) { int d = r10_bio->devs[i].devnum; mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev); - if (rdev && - !test_bit(Faulty, &rdev->flags)) { + if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) { + atomic_inc(&rdev->nr_pending); + blocked_rdev = rdev; + break; + } + if (rdev && !test_bit(Faulty, &rdev->flags)) { atomic_inc(&rdev->nr_pending); r10_bio->devs[i].bio = bio; } else { @@ -899,6 +906,22 @@ static int make_request(struct request_queue *q, struct bio * bio) } rcu_read_unlock(); + if (unlikely(blocked_rdev)) { + /* Have to wait for this device to get unblocked, then retry */ + int j; + int d; + + for (j = 0; j < i; j++) + if (r10_bio->devs[j].bio) { + d = r10_bio->devs[j].devnum; + rdev_dec_pending(conf->mirrors[d].rdev, mddev); + } + allow_barrier(conf); + md_wait_for_blocked_rdev(blocked_rdev, mddev); + wait_barrier(conf); + goto retry_write; + } + atomic_set(&r10_bio->remaining, 0); bio_list_init(&bl); -- cgit v1.2.3