Btrfs: Catch missed bios in the async bio submission thread

The async bio submission thread was missing some bios that were
added after it had decided there was no work left to do.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index fd0bedb07a64..bcd14ebccae1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -154,6 +154,7 @@ static noinline int run_scheduled_bios(struct btrfs_device *device)
 loop:
         spin_lock(&device->io_lock);
 
+loop_lock:
         /* take all the bios off the list at once and process them
          * later on (without the lock held).  But, remember the
          * tail and other pointers so the bios can be properly reinserted
@@ -203,7 +204,7 @@ loop:
                  * is now congested.  Back off and let other work structs
                  * run instead
                  */
-                if (pending && bdi_write_congested(bdi) &&
+                if (pending && bdi_write_congested(bdi) && num_run > 16 &&
                     fs_info->fs_devices->open_devices > 1) {
                         struct bio *old_head;
 
@@ -215,7 +216,8 @@ loop:
                                 tail->bi_next = old_head;
                         else
                                 device->pending_bio_tail = tail;
-                        device->running_pending = 0;
+
+                        device->running_pending = 1;
 
                         spin_unlock(&device->io_lock);
                         btrfs_requeue_work(&device->work);
@@ -224,6 +226,11 @@ loop:
         }
         if (again)
                 goto loop;
+
+        spin_lock(&device->io_lock);
+        if (device->pending_bios)
+                goto loop_lock;
+        spin_unlock(&device->io_lock);
 done:
         return 0;
 }