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>
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 1394aa3..3ccadc1 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -498,7 +498,6 @@
struct cifsTconInfo *tcon;
struct cifsInodeInfo *pCifsInode;
struct cifsFileInfo *netfile;
- int rc;
cFYI(1, "Checking for oplock break or dnotify response");
if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
@@ -583,13 +582,18 @@
pCifsInode->clientCanCacheAll = false;
if (pSMB->OplockLevel == 0)
pCifsInode->clientCanCacheRead = false;
- rc = slow_work_enqueue(&netfile->oplock_break);
- if (rc) {
- cERROR(1, "failed to enqueue oplock "
- "break: %d\n", rc);
- } else {
- netfile->oplock_break_cancelled = false;
- }
+
+ /*
+ * cifs_oplock_break_put() can't be called
+ * from here. Get reference after queueing
+ * succeeded. cifs_oplock_break() will
+ * synchronize using GlobalSMSSeslock.
+ */
+ if (queue_work(system_nrt_wq,
+ &netfile->oplock_break))
+ cifs_oplock_break_get(netfile);
+ netfile->oplock_break_cancelled = false;
+
read_unlock(&GlobalSMBSeslock);
read_unlock(&cifs_tcp_ses_lock);
return true;