[linux-cifs-client] [PATCH 1/4] cifs: protect GlobalOplock_Q with its own mutex

[Jeff Layton]

Right now, the GlobalOplock_Q is protected by the GlobalMid_Lock. That
lock is also used for completely unrelated purposes (mostly for managing
the global mid queue). Give the list its own dedicated mutex
(cifs_oplock_mutex). Also, rename the list to cifs_oplock_list to
eliminate the camel-case.

Signed-off-by: Jeff Layton <jlayton at redhat.com>
---
 fs/cifs/cifsfs.c    |   13 +++++++------
 fs/cifs/cifsglob.h  |    6 +++++-
 fs/cifs/transport.c |   17 ++++++++---------
 3 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index b750aa5..0d4e0da 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -986,19 +986,19 @@ static int cifs_oplock_thread(void *dummyarg)
 		if (try_to_freeze())
 			continue;
 
-		spin_lock(&GlobalMid_Lock);
-		if (list_empty(&GlobalOplock_Q)) {
-			spin_unlock(&GlobalMid_Lock);
+		mutex_lock(&cifs_oplock_mutex);
+		if (list_empty(&cifs_oplock_list)) {
+			mutex_unlock(&cifs_oplock_mutex);
 			set_current_state(TASK_INTERRUPTIBLE);
 			schedule_timeout(39*HZ);
 		} else {
-			oplock_item = list_entry(GlobalOplock_Q.next,
+			oplock_item = list_entry(cifs_oplock_list.next,
 						struct oplock_q_entry, qhead);
 			cFYI(1, ("found oplock item to write out"));
 			pTcon = oplock_item->tcon;
 			inode = oplock_item->pinode;
 			netfid = oplock_item->netfid;
-			spin_unlock(&GlobalMid_Lock);
+			mutex_unlock(&cifs_oplock_mutex);
 			DeleteOplockQEntry(oplock_item);
 			/* can not grab inode sem here since it would
 				deadlock when oplock received on delete
@@ -1055,7 +1055,8 @@ init_cifs(void)
 	int rc = 0;
 	cifs_proc_init();
 	INIT_LIST_HEAD(&cifs_tcp_ses_list);
-	INIT_LIST_HEAD(&GlobalOplock_Q);
+	INIT_LIST_HEAD(&cifs_oplock_list);
+	mutex_init(&cifs_oplock_mutex);
 #ifdef CONFIG_CIFS_EXPERIMENTAL
 	INIT_LIST_HEAD(&GlobalDnotifyReqList);
 	INIT_LIST_HEAD(&GlobalDnotifyRsp_Q);
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 6084d63..a1896e9 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -656,7 +656,11 @@ GLOBAL_EXTERN rwlock_t		cifs_tcp_ses_lock;
  */
 GLOBAL_EXTERN rwlock_t GlobalSMBSeslock;
 
-GLOBAL_EXTERN struct list_head GlobalOplock_Q;
+/* Global list of oplocks */
+GLOBAL_EXTERN struct list_head cifs_oplock_list;
+
+/* Protects the cifs_oplock_list */
+GLOBAL_EXTERN struct mutex cifs_oplock_mutex;
 
 /* Outstanding dir notify requests */
 GLOBAL_EXTERN struct list_head GlobalDnotifyReqList;
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 0ad3e2d..92e1538 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -119,20 +119,19 @@ AllocOplockQEntry(struct inode *pinode, __u16 fid, struct cifsTconInfo *tcon)
 		temp->pinode = pinode;
 		temp->tcon = tcon;
 		temp->netfid = fid;
-		spin_lock(&GlobalMid_Lock);
-		list_add_tail(&temp->qhead, &GlobalOplock_Q);
-		spin_unlock(&GlobalMid_Lock);
+		mutex_lock(&cifs_oplock_mutex);
+		list_add_tail(&temp->qhead, &cifs_oplock_list);
+		mutex_unlock(&cifs_oplock_mutex);
 	}
 	return temp;
-
 }
 
 void DeleteOplockQEntry(struct oplock_q_entry *oplockEntry)
 {
-	spin_lock(&GlobalMid_Lock);
+	mutex_lock(&cifs_oplock_mutex);
     /* should we check if list empty first? */
 	list_del(&oplockEntry->qhead);
-	spin_unlock(&GlobalMid_Lock);
+	mutex_unlock(&cifs_oplock_mutex);
 	kmem_cache_free(cifs_oplock_cachep, oplockEntry);
 }
 
@@ -144,14 +143,14 @@ void DeleteTconOplockQEntries(struct cifsTconInfo *tcon)
 	if (tcon == NULL)
 		return;
 
-	spin_lock(&GlobalMid_Lock);
-	list_for_each_entry(temp, &GlobalOplock_Q, qhead) {
+	mutex_lock(&cifs_oplock_mutex);
+	list_for_each_entry(temp, &cifs_oplock_list, qhead) {
 		if ((temp->tcon) && (temp->tcon == tcon)) {
 			list_del(&temp->qhead);
 			kmem_cache_free(cifs_oplock_cachep, temp);
 		}
 	}
-	spin_unlock(&GlobalMid_Lock);
+	mutex_unlock(&cifs_oplock_mutex);
 }
 
 static int
-- 
1.6.0.6