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 <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>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 9fd473a..6778b7c 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -773,7 +773,6 @@
r1bio_t *r1_bio;
struct bio *read_bio;
int i, targets = 0, disks;
- mdk_rdev_t *rdev;
struct bitmap *bitmap = mddev->bitmap;
unsigned long flags;
struct bio_list bl;
@@ -781,6 +780,7 @@
const int rw = bio_data_dir(bio);
const int do_sync = bio_sync(bio);
int do_barriers;
+ mdk_rdev_t *blocked_rdev;
/*
* Register the new request and wait if the reconstruction
@@ -862,10 +862,17 @@
first = 0;
}
#endif
+ retry_write:
+ blocked_rdev = NULL;
rcu_read_lock();
for (i = 0; i < disks; i++) {
- if ((rdev=rcu_dereference(conf->mirrors[i].rdev)) != NULL &&
- !test_bit(Faulty, &rdev->flags)) {
+ mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
+ 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);
if (test_bit(Faulty, &rdev->flags)) {
rdev_dec_pending(rdev, mddev);
@@ -878,6 +885,20 @@
}
rcu_read_unlock();
+ if (unlikely(blocked_rdev)) {
+ /* Wait for this device to become unblocked */
+ int j;
+
+ for (j = 0; j < i; j++)
+ if (r1_bio->bios[j])
+ rdev_dec_pending(conf->mirrors[j].rdev, mddev);
+
+ allow_barrier(conf);
+ md_wait_for_blocked_rdev(blocked_rdev, mddev);
+ wait_barrier(conf);
+ goto retry_write;
+ }
+
BUG_ON(targets == 0); /* we never fail the last device */
if (targets < conf->raid_disks) {