Btrfs: Add a thread pool just for submit_bio

If a bio submission is after a lock holder waiting for the bio
on the work queue, it is possible to deadlock.  Move the bios
into their own pool.

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

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c57458ce6339..ba3968571024 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2112,7 +2112,8 @@ int schedule_bio(struct btrfs_root *root, struct btrfs_device *device,
         spin_unlock(&device->io_lock);
 
         if (should_queue)
-                btrfs_queue_worker(&root->fs_info->workers, &device->work);
+                btrfs_queue_worker(&root->fs_info->submit_workers,
+                                   &device->work);
         return 0;
 }