cifs: add new cifsiod_wq workqueue

...and convert existing cifs users of system_nrt_wq to use that instead.

Also, make it freezable, and set WQ_MEM_RECLAIM since we use it to
deal with write reply handling.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>

fs/cifs/cifsfs.c

@@ -85,6 +85,8 @@ extern mempool_t *cifs_sm_req_poolp;
 extern mempool_t *cifs_req_poolp;
 extern mempool_t *cifs_mid_poolp;
 
+struct workqueue_struct	*cifsiod_wq;
+
 static int
 cifs_read_super(struct super_block *sb)
 {
@@ -1111,9 +1113,15 @@ init_cifs(void)
 		cFYI(1, "cifs_max_pending set to max of %u", CIFS_MAX_REQ);
 	}
 
+	cifsiod_wq = alloc_workqueue("cifsiod", WQ_FREEZABLE|WQ_MEM_RECLAIM, 0);
+	if (!cifsiod_wq) {
+		rc = -ENOMEM;
+		goto out_clean_proc;
+	}
+
 	rc = cifs_fscache_register();
 	if (rc)
-		goto out_clean_proc;
+		goto out_destroy_wq;
 
 	rc = cifs_init_inodecache();
 	if (rc)
@@ -1161,6 +1169,8 @@ init_cifs(void)
 	cifs_destroy_inodecache();
 out_unreg_fscache:
 	cifs_fscache_unregister();
+out_destroy_wq:
+	destroy_workqueue(cifsiod_wq);
 out_clean_proc:
 	cifs_proc_clean();
 	return rc;
@@ -1183,6 +1193,7 @@ exit_cifs(void)
 	cifs_destroy_mids();
 	cifs_destroy_inodecache();
 	cifs_fscache_unregister();
+	destroy_workqueue(cifsiod_wq);
 	cifs_proc_clean();
 }
 

fs/cifs/cifsglob.h

@@ -1070,5 +1070,6 @@ GLOBAL_EXTERN spinlock_t gidsidlock;
 void cifs_oplock_break(struct work_struct *work);
 
 extern const struct slow_work_ops cifs_oplock_break_ops;
+extern struct workqueue_struct *cifsiod_wq;
 
 #endif	/* _CIFS_GLOB_H */

fs/cifs/cifssmb.c

@@ -1689,7 +1689,7 @@ cifs_readv_callback(struct mid_q_entry *mid)
 		rdata->result = -EIO;
 	}
 
-	queue_work(system_nrt_wq, &rdata->work);
+	queue_work(cifsiod_wq, &rdata->work);
 	DeleteMidQEntry(mid);
 	cifs_add_credits(server, 1);
 }
@@ -2129,7 +2129,7 @@ cifs_writev_callback(struct mid_q_entry *mid)
 		break;
 	}
 
-	queue_work(system_nrt_wq, &wdata->work);
+	queue_work(cifsiod_wq, &wdata->work);
 	DeleteMidQEntry(mid);
 	cifs_add_credits(tcon->ses->server, 1);
 }

fs/cifs/connect.c

@@ -335,7 +335,7 @@ cifs_echo_request(struct work_struct *work)
 			server->hostname);
 
 requeue_echo:
-	queue_delayed_work(system_nrt_wq, &server->echo, SMB_ECHO_INTERVAL);
+	queue_delayed_work(cifsiod_wq, &server->echo, SMB_ECHO_INTERVAL);
 }
 
 static bool
@@ -1971,7 +1971,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
 	cifs_fscache_get_client_cookie(tcp_ses);
 
 	/* queue echo request delayed work */
-	queue_delayed_work(system_nrt_wq, &tcp_ses->echo, SMB_ECHO_INTERVAL);
+	queue_delayed_work(cifsiod_wq, &tcp_ses->echo, SMB_ECHO_INTERVAL);
 
 	return tcp_ses;
 
@@ -3537,7 +3537,7 @@ cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *volume_info)
 	tlink_rb_insert(&cifs_sb->tlink_tree, tlink);
 	spin_unlock(&cifs_sb->tlink_tree_lock);
 
-	queue_delayed_work(system_nrt_wq, &cifs_sb->prune_tlinks,
+	queue_delayed_work(cifsiod_wq, &cifs_sb->prune_tlinks,
 				TLINK_IDLE_EXPIRE);
 
 mount_fail_check:
@@ -4091,6 +4091,6 @@ cifs_prune_tlinks(struct work_struct *work)
 	}
 	spin_unlock(&cifs_sb->tlink_tree_lock);
 
-	queue_delayed_work(system_nrt_wq, &cifs_sb->prune_tlinks,
+	queue_delayed_work(cifsiod_wq, &cifs_sb->prune_tlinks,
 				TLINK_IDLE_EXPIRE);
 }

fs/cifs/misc.c

@@ -595,7 +595,7 @@ is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
 
 				cifs_set_oplock_level(pCifsInode,
 					pSMB->OplockLevel ? OPLOCK_READ : 0);
-				queue_work(system_nrt_wq,
+				queue_work(cifsiod_wq,
 					   &netfile->oplock_break);
 				netfile->oplock_break_cancelled = false;