cifs: use workqueue instead of slow-work

Workqueue can now handle high concurrency.  Use system_nrt_wq
instead of slow-work.

* Updated is_valid_oplock_break() to not call cifs_oplock_break_put()
  as advised by Steve French.  It might cause deadlock.  Instead,
  reference is increased after queueing succeeded and
  cifs_oplock_break() briefly grabs GlobalSMBSeslock before putting
  the cfile to make sure it doesn't put before the matching get is
  finished.

* Anton Blanchard reported that cifs conversion was using now gone
  system_single_wq.  Use system_nrt_wq which provides non-reentrance
  guarantee which is enough and much better.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Steve French <sfrench@samba.org>
Cc: Anton Blanchard <anton@samba.org>

1 files changed, 0 insertions, 5 deletions

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 78c02eb4cb1..4c075177c8b 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -917,15 +917,10 @@ init_cifs(void)
         if (rc)
                 goto out_unregister_key_type;
 #endif
-        rc = slow_work_register_user(THIS_MODULE);
-        if (rc)
-                goto out_unregister_resolver_key;
 
         return 0;
 
- out_unregister_resolver_key:
 #ifdef CONFIG_CIFS_DFS_UPCALL
-        unregister_key_type(&key_type_dns_resolver);
  out_unregister_key_type:
 #endif
 #ifdef CONFIG_CIFS_UPCALL