cifs: reinstate sharing of tree connections

Use a similar approach to the SMB session sharing. Add a list of tcons
attached to each SMB session. Move the refcount to non-atomic. Protect
all of the above with the cifs_tcp_ses_lock. Add functions to
properly find and put references to the tcons.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 631a99f72f22..f1ae1f57c30d 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -233,16 +233,15 @@ struct cifsSesInfo {
  * session
  */
 struct cifsTconInfo {
-        struct list_head cifsConnectionList;
+        struct list_head tcon_list;
+        int tc_count;
         struct list_head openFileList;
-        struct semaphore tconSem;
         struct cifsSesInfo *ses;        /* pointer to session associated with */
         char treeName[MAX_TREE_SIZE + 1]; /* UNC name of resource in ASCII */
         char *nativeFileSystem;
         __u16 tid;              /* The 2 byte tree id */
         __u16 Flags;            /* optional support bits */
         enum statusEnum tidStatus;
-        atomic_t useCount;      /* how many explicit/implicit mounts to share */
 #ifdef CONFIG_CIFS_STATS
         atomic_t num_smbs_sent;
         atomic_t num_writes;
@@ -600,9 +599,13 @@ require use of the stronger protocol */
  */
 GLOBAL_EXTERN struct list_head          cifs_tcp_ses_list;
 
-/* protects cifs_tcp_ses_list and srv_count for each tcp session */
+/*
+ * This lock protects the cifs_tcp_ses_list, the list of smb sessions per
+ * tcp session, and the list of tcon's per smb session. It also protects
+ * the reference counters for the server, smb session, and tcon. Finally,
+ * changes to the tcon->tidStatus should be done while holding this lock.
+ */
 GLOBAL_EXTERN rwlock_t          cifs_tcp_ses_lock;
-GLOBAL_EXTERN struct list_head GlobalTreeConnectionList; /* BB to be removed */
 GLOBAL_EXTERN rwlock_t GlobalSMBSeslock;  /* protects list inserts on 3 above */
 
 GLOBAL_EXTERN struct list_head GlobalOplock_Q;