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md: support blocking writes to an array on device failure

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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 <dan.j.williams@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams
2008-04-30 00:52:32 -07:00
committed by Linus Torvalds
parent 11e2ede022
commit 6bfe0b4990
6 changed files with 120 additions and 7 deletions
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29
drivers/md/raid10.c
View File

@@ -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);