raid5-cache: add journal hot add/remove support
Add support for journal disk hot add/remove. Mostly trival checks in md
part. The raid5 part is a little tricky. For hot-remove, we can't wait
pending write as it's called from raid5d. The wait will cause deadlock.
We simplily fail the hot-remove. A hot-remove retry can success
eventually since if journal disk is faulty all pending write will be
failed and finish. For hot-add, since an array supporting journal but
without journal disk will be marked read-only, we are safe to hot add
journal without stopping IO (should be read IO, while journal only
handles write IO).
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 668e973..c1c4d21 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -799,10 +799,18 @@
bool r5l_log_disk_error(struct r5conf *conf)
{
+ struct r5l_log *log;
+ bool ret;
/* don't allow write if journal disk is missing */
- if (!conf->log)
- return test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
- return test_bit(Faulty, &conf->log->rdev->flags);
+ rcu_read_lock();
+ log = rcu_dereference(conf->log);
+
+ if (!log)
+ ret = test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
+ else
+ ret = test_bit(Faulty, &log->rdev->flags);
+ rcu_read_unlock();
+ return ret;
}
struct r5l_recovery_ctx {
@@ -1165,7 +1173,7 @@
if (r5l_load_log(log))
goto error;
- conf->log = log;
+ rcu_assign_pointer(conf->log, log);
return 0;
error:
md_unregister_thread(&log->reclaim_thread);