md/raid5: Refactor raid5_get_active_stripe()

Refactor raid5_get_active_stripe() without the gotos with an
explicit infinite loop and some additional nesting.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Song Liu <song@kernel.org>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 31a0cbf..e7a7ca3 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -811,54 +811,54 @@ static struct stripe_head *__raid5_get_active_stripe(struct r5conf *conf,
 
        spin_lock_irq(conf->hash_locks + hash);
 
-retry:
-       if (!noquiesce && conf->quiesce) {
-               /*
-                * Must release the reference to batch_last before waiting,
-                * on quiesce, otherwise the batch_last will hold a reference
-                * to a stripe and raid5_quiesce() will deadlock waiting for
-                * active_stripes to go to zero.
-                */
-               if (ctx && ctx->batch_last) {
-                       raid5_release_stripe(ctx->batch_last);
-                       ctx->batch_last = NULL;
-               }
-
-               wait_event_lock_irq(conf->wait_for_quiescent, !conf->quiesce,
-                                   *(conf->hash_locks + hash));
-       }
+       for (;;) {
+               if (!noquiesce && conf->quiesce) {
+                       /*
+                        * Must release the reference to batch_last before
+                        * waiting, on quiesce, otherwise the batch_last will
+                        * hold a reference to a stripe and raid5_quiesce()
+                        * will deadlock waiting for active_stripes to go to
+                        * zero.
+                        */
+                       if (ctx && ctx->batch_last) {
+                               raid5_release_stripe(ctx->batch_last);
+                               ctx->batch_last = NULL;
+                       }
 
-       sh = find_get_stripe(conf, sector, conf->generation - previous, hash);
-       if (sh)
-               goto out;
+                       wait_event_lock_irq(conf->wait_for_quiescent,
+                                           !conf->quiesce,
+                                           *(conf->hash_locks + hash));
+               }
 
-       if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
-               goto wait_for_stripe;
+               sh = find_get_stripe(conf, sector, conf->generation - previous,
+                                    hash);
+               if (sh)
+                       break;
 
-       sh = get_free_stripe(conf, hash);
-       if (sh) {
-               r5c_check_stripe_cache_usage(conf);
-               init_stripe(sh, sector, previous);
-               atomic_inc(&sh->count);
-               goto out;
-       }
+               if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
+                       sh = get_free_stripe(conf, hash);
+                       if (sh) {
+                               r5c_check_stripe_cache_usage(conf);
+                               init_stripe(sh, sector, previous);
+                               atomic_inc(&sh->count);
+                               break;
+                       }
 
-       if (!test_bit(R5_DID_ALLOC, &conf->cache_state))
-               set_bit(R5_ALLOC_MORE, &conf->cache_state);
+                       if (!test_bit(R5_DID_ALLOC, &conf->cache_state))
+                               set_bit(R5_ALLOC_MORE, &conf->cache_state);
+               }
 
-wait_for_stripe:
-       if (noblock)
-               goto out;
+               if (noblock)
+                       break;
 
-       set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
-       r5l_wake_reclaim(conf->log, 0);
-       wait_event_lock_irq(conf->wait_for_stripe,
-                           is_inactive_blocked(conf, hash),
-                           *(conf->hash_locks + hash));
-       clear_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
-       goto retry;
+               set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
+               r5l_wake_reclaim(conf->log, 0);
+               wait_event_lock_irq(conf->wait_for_stripe,
+                                   is_inactive_blocked(conf, hash),
+                                   *(conf->hash_locks + hash));
+               clear_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
+       }
 
-out:
        spin_unlock_irq(conf->hash_locks + hash);
        return sh;
 }