raid5-cache: don't delay stripe captured in log

There is a case a stripe gets delayed forever.
1. a stripe finishes construction
2. a new bio hits the stripe
3. handle_stripe runs for the stripe. The stripe gets DELAYED bit set
since construction can't run for new bio (the stripe is locked since
step 1)

Without log, handle_stripe will call ops_run_io. After IO finishes, the
stripe gets unlocked and the stripe will restart and run construction
for the new bio. With log, ops_run_io need to run two times. If the
DELAYED bit set, the stripe can't enter into the handle_list, so the
second ops_run_io doesn't run, which leaves the stripe stalled.

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 30c7e5e79a02ef1575d9124089adb82c4f8137a0..0460882a5fd74517fc21b6bbc0b3b6fc1e9f5bb2 100644 (file)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -479,6 +479,11 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
                return -EINVAL;
 
        set_bit(STRIPE_LOG_TRAPPED, &sh->state);
+       /*
+        * The stripe must enter state machine again to finish the write, so
+        * don't delay.
+        */
+       clear_bit(STRIPE_DELAYED, &sh->state);
        atomic_inc(&sh->count);
 
        mutex_lock(&log->io_mutex);