1 files changed, 43 insertions, 29 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 08fcaebc61bd..0ff1bbf6c90e 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -266,6 +266,37 @@ static DEFINE_SPINLOCK(all_mddevs_lock);
  * call has finished, the bio has been linked into some internal structure
  * and so is visible to ->quiesce(), so we don't need the refcount any more.
  */
+void md_handle_request(struct mddev *mddev, struct bio *bio)
+{
+check_suspended:
+        rcu_read_lock();
+        if (mddev->suspended) {
+                DEFINE_WAIT(__wait);
+                for (;;) {
+                        prepare_to_wait(&mddev->sb_wait, &__wait,
+                                        TASK_UNINTERRUPTIBLE);
+                        if (!mddev->suspended)
+                                break;
+                        rcu_read_unlock();
+                        schedule();
+                        rcu_read_lock();
+                }
+                finish_wait(&mddev->sb_wait, &__wait);
+        }
+        atomic_inc(&mddev->active_io);
+        rcu_read_unlock();
+
+        if (!mddev->pers->make_request(mddev, bio)) {
+                atomic_dec(&mddev->active_io);
+                wake_up(&mddev->sb_wait);
+                goto check_suspended;
+        }
+
+        if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
+                wake_up(&mddev->sb_wait);
+}
+EXPORT_SYMBOL(md_handle_request);
+
 static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
 {
         const int rw = bio_data_dir(bio);
@@ -285,23 +316,6 @@ static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
                 bio_endio(bio);
                 return BLK_QC_T_NONE;
         }
-check_suspended:
-        rcu_read_lock();
-        if (mddev->suspended) {
-                DEFINE_WAIT(__wait);
-                for (;;) {
-                        prepare_to_wait(&mddev->sb_wait, &__wait,
-                                        TASK_UNINTERRUPTIBLE);
-                        if (!mddev->suspended)
-                                break;
-                        rcu_read_unlock();
-                        schedule();
-                        rcu_read_lock();
-                }
-                finish_wait(&mddev->sb_wait, &__wait);
-        }
-        atomic_inc(&mddev->active_io);
-        rcu_read_unlock();
 
         /*
          * save the sectors now since our bio can
@@ -310,20 +324,14 @@ check_suspended:
         sectors = bio_sectors(bio);
         /* bio could be mergeable after passing to underlayer */
         bio->bi_opf &= ~REQ_NOMERGE;
-        if (!mddev->pers->make_request(mddev, bio)) {
-                atomic_dec(&mddev->active_io);
-                wake_up(&mddev->sb_wait);
-                goto check_suspended;
-        }
+
+        md_handle_request(mddev, bio);
 
         cpu = part_stat_lock();
         part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
         part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);
         part_stat_unlock();
 
-        if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
-                wake_up(&mddev->sb_wait);
-
         return BLK_QC_T_NONE;
 }
 
@@ -439,16 +447,22 @@ static void md_submit_flush_data(struct work_struct *ws)
         struct mddev *mddev = container_of(ws, struct mddev, flush_work);
         struct bio *bio = mddev->flush_bio;
 
+        /*
+         * must reset flush_bio before calling into md_handle_request to avoid a
+         * deadlock, because other bios passed md_handle_request suspend check
+         * could wait for this and below md_handle_request could wait for those
+         * bios because of suspend check
+         */
+        mddev->flush_bio = NULL;
+        wake_up(&mddev->sb_wait);
+
         if (bio->bi_iter.bi_size == 0)
                 /* an empty barrier - all done */
                 bio_endio(bio);
         else {
                 bio->bi_opf &= ~REQ_PREFLUSH;
-                mddev->pers->make_request(mddev, bio);
+                md_handle_request(mddev, bio);
         }
-
-        mddev->flush_bio = NULL;
-        wake_up(&mddev->sb_wait);
 }
 
 void md_flush_request(struct mddev *mddev, struct bio *bio)