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>

6 files changed, 249 insertions, 218 deletions

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index 59841a68b0b6..1d6dfa8923ca 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -107,12 +107,13 @@ void cifs_dump_mids(struct TCP_Server_Info *server)
 #ifdef CONFIG_PROC_FS
 static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 {
-        struct list_head *tmp, *tmp2, *tmp3;
+        struct list_head *tmp1, *tmp2, *tmp3;
         struct mid_q_entry *mid_entry;
         struct TCP_Server_Info *server;
         struct cifsSesInfo *ses;
         struct cifsTconInfo *tcon;
-        int i;
+        int i, j;
+        __u32 dev_type;
 
         seq_puts(m,
                     "Display Internal CIFS Data Structures for Debugging\n"
@@ -123,8 +124,8 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 
         i = 0;
         read_lock(&cifs_tcp_ses_lock);
-        list_for_each(tmp, &cifs_tcp_ses_list) {
-                server = list_entry(tmp, struct TCP_Server_Info,
+        list_for_each(tmp1, &cifs_tcp_ses_list) {
+                server = list_entry(tmp1, struct TCP_Server_Info,
                                     tcp_ses_list);
                 i++;
                 list_for_each(tmp2, &server->smb_ses_list) {
@@ -133,12 +134,12 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
                         if ((ses->serverDomain == NULL) ||
                                 (ses->serverOS == NULL) ||
                                 (ses->serverNOS == NULL)) {
-                                seq_printf(m, "\nentry for %s not fully "
-                                           "displayed\n\t", ses->serverName);
+                                seq_printf(m, "\n%d) entry for %s not fully "
+                                           "displayed\n\t", i, ses->serverName);
                         } else {
                                 seq_printf(m,
-                                    "\n%d) Name: %s  Domain: %s Mounts: %d OS:"
-                                    " %s  \n\tNOS: %s\tCapability: 0x%x\n\tSMB"
+                                    "\n%d) Name: %s  Domain: %s Uses: %d OS:"
+                                    " %s\n\tNOS: %s\tCapability: 0x%x\n\tSMB"
                                     " session status: %d\t",
                                 i, ses->serverName, ses->serverDomain,
                                 ses->ses_count, ses->serverOS, ses->serverNOS,
@@ -156,14 +157,44 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
                                 atomic_read(&server->num_waiters));
 #endif
 
-                        seq_puts(m, "\nMIDs:\n");
+                        seq_puts(m, "\n\tShares:");
+                        j = 0;
+                        list_for_each(tmp3, &ses->tcon_list) {
+                                tcon = list_entry(tmp3, struct cifsTconInfo,
+                                                  tcon_list);
+                                ++j;
+                                dev_type = le32_to_cpu(tcon->fsDevInfo.DeviceType);
+                                seq_printf(m, "\n\t%d) %s Mounts: %d ", j,
+                                           tcon->treeName, tcon->tc_count);
+                                if (tcon->nativeFileSystem) {
+                                        seq_printf(m, "Type: %s ",
+                                                   tcon->nativeFileSystem);
+                                }
+                                seq_printf(m, "DevInfo: 0x%x Attributes: 0x%x"
+                                        "\nPathComponentMax: %d Status: 0x%d",
+                                        le32_to_cpu(tcon->fsDevInfo.DeviceCharacteristics),
+                                        le32_to_cpu(tcon->fsAttrInfo.Attributes),
+                                        le32_to_cpu(tcon->fsAttrInfo.MaxPathNameComponentLength),
+                                        tcon->tidStatus);
+                                if (dev_type == FILE_DEVICE_DISK)
+                                        seq_puts(m, " type: DISK ");
+                                else if (dev_type == FILE_DEVICE_CD_ROM)
+                                        seq_puts(m, " type: CDROM ");
+                                else
+                                        seq_printf(m, " type: %d ", dev_type);
+
+                                if (tcon->need_reconnect)
+                                        seq_puts(m, "\tDISCONNECTED ");
+                                seq_putc(m, '\n');
+                        }
+
+                        seq_puts(m, "\n\tMIDs:\n");
 
                         spin_lock(&GlobalMid_Lock);
                         list_for_each(tmp3, &server->pending_mid_q) {
-                                mid_entry = list_entry(tmp3, struct
-                                        mid_q_entry,
+                                mid_entry = list_entry(tmp3, struct mid_q_entry,
                                         qhead);
-                                seq_printf(m, "State: %d com: %d pid:"
+                                seq_printf(m, "\tState: %d com: %d pid:"
                                                 " %d tsk: %p mid %d\n",
                                                 mid_entry->midState,
                                                 (int)mid_entry->command,
@@ -177,41 +208,6 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
         read_unlock(&cifs_tcp_ses_lock);
         seq_putc(m, '\n');
 
-        seq_puts(m, "Shares:");
-
-        i = 0;
-        read_lock(&GlobalSMBSeslock);
-        list_for_each(tmp, &GlobalTreeConnectionList) {
-                __u32 dev_type;
-                i++;
-                tcon = list_entry(tmp, struct cifsTconInfo, cifsConnectionList);
-                dev_type = le32_to_cpu(tcon->fsDevInfo.DeviceType);
-                seq_printf(m, "\n%d) %s Uses: %d ", i,
-                                 tcon->treeName, atomic_read(&tcon->useCount));
-                if (tcon->nativeFileSystem) {
-                        seq_printf(m, "Type: %s ",
-                                         tcon->nativeFileSystem);
-                }
-                seq_printf(m, "DevInfo: 0x%x Attributes: 0x%x"
-                                 "\nPathComponentMax: %d Status: %d",
-                            le32_to_cpu(tcon->fsDevInfo.DeviceCharacteristics),
-                            le32_to_cpu(tcon->fsAttrInfo.Attributes),
-                            le32_to_cpu(tcon->fsAttrInfo.MaxPathNameComponentLength),
-                            tcon->tidStatus);
-                if (dev_type == FILE_DEVICE_DISK)
-                        seq_puts(m, " type: DISK ");
-                else if (dev_type == FILE_DEVICE_CD_ROM)
-                        seq_puts(m, " type: CDROM ");
-                else
-                        seq_printf(m, " type: %d ", dev_type);
-
-                if (tcon->need_reconnect)
-                        seq_puts(m, "\tDISCONNECTED ");
-        }
-        read_unlock(&GlobalSMBSeslock);
-
-        seq_putc(m, '\n');
-
         /* BB add code to dump additional info such as TCP session info now */
         return 0;
 }
@@ -235,7 +231,9 @@ static ssize_t cifs_stats_proc_write(struct file *file,
 {
         char c;
         int rc;
-        struct list_head *tmp;
+        struct list_head *tmp1, *tmp2, *tmp3;
+        struct TCP_Server_Info *server;
+        struct cifsSesInfo *ses;
         struct cifsTconInfo *tcon;
 
         rc = get_user(c, buffer);
@@ -243,33 +241,42 @@ static ssize_t cifs_stats_proc_write(struct file *file,
                 return rc;
 
         if (c == '1' || c == 'y' || c == 'Y' || c == '0') {
-                read_lock(&GlobalSMBSeslock);
 #ifdef CONFIG_CIFS_STATS2
                 atomic_set(&totBufAllocCount, 0);
                 atomic_set(&totSmBufAllocCount, 0);
 #endif /* CONFIG_CIFS_STATS2 */
-                list_for_each(tmp, &GlobalTreeConnectionList) {
-                        tcon = list_entry(tmp, struct cifsTconInfo,
-                                        cifsConnectionList);
-                        atomic_set(&tcon->num_smbs_sent, 0);
-                        atomic_set(&tcon->num_writes, 0);
-                        atomic_set(&tcon->num_reads, 0);
-                        atomic_set(&tcon->num_oplock_brks, 0);
-                        atomic_set(&tcon->num_opens, 0);
-                        atomic_set(&tcon->num_closes, 0);
-                        atomic_set(&tcon->num_deletes, 0);
-                        atomic_set(&tcon->num_mkdirs, 0);
-                        atomic_set(&tcon->num_rmdirs, 0);
-                        atomic_set(&tcon->num_renames, 0);
-                        atomic_set(&tcon->num_t2renames, 0);
-                        atomic_set(&tcon->num_ffirst, 0);
-                        atomic_set(&tcon->num_fnext, 0);
-                        atomic_set(&tcon->num_fclose, 0);
-                        atomic_set(&tcon->num_hardlinks, 0);
-                        atomic_set(&tcon->num_symlinks, 0);
-                        atomic_set(&tcon->num_locks, 0);
+                read_lock(&cifs_tcp_ses_lock);
+                list_for_each(tmp1, &cifs_tcp_ses_list) {
+                        server = list_entry(tmp1, struct TCP_Server_Info,
+                                            tcp_ses_list);
+                        list_for_each(tmp2, &server->smb_session_list) {
+                                ses = list_entry(tmp2, struct cifsSesInfo,
+                                                 smb_session_list);
+                                list_for_each(tmp3, &ses->tcon_list) {
+                                        tcon = list_entry(tmp3,
+                                                          struct cifsTconInfo,
+                                                          tcon_list);
+                                        atomic_set(&tcon->num_smbs_sent, 0);
+                                        atomic_set(&tcon->num_writes, 0);
+                                        atomic_set(&tcon->num_reads, 0);
+                                        atomic_set(&tcon->num_oplock_brks, 0);
+                                        atomic_set(&tcon->num_opens, 0);
+                                        atomic_set(&tcon->num_closes, 0);
+                                        atomic_set(&tcon->num_deletes, 0);
+                                        atomic_set(&tcon->num_mkdirs, 0);
+                                        atomic_set(&tcon->num_rmdirs, 0);
+                                        atomic_set(&tcon->num_renames, 0);
+                                        atomic_set(&tcon->num_t2renames, 0);
+                                        atomic_set(&tcon->num_ffirst, 0);
+                                        atomic_set(&tcon->num_fnext, 0);
+                                        atomic_set(&tcon->num_fclose, 0);
+                                        atomic_set(&tcon->num_hardlinks, 0);
+                                        atomic_set(&tcon->num_symlinks, 0);
+                                        atomic_set(&tcon->num_locks, 0);
+                                }
+                        }
                 }
-                read_unlock(&GlobalSMBSeslock);
+                read_unlock(&cifs_tcp_ses_lock);
         }
 
         return count;
@@ -278,7 +285,9 @@ static ssize_t cifs_stats_proc_write(struct file *file,
 static int cifs_stats_proc_show(struct seq_file *m, void *v)
 {
         int i;
-        struct list_head *tmp;
+        struct list_head *tmp1, *tmp2, *tmp3;
+        struct TCP_Server_Info *server;
+        struct cifsSesInfo *ses;
         struct cifsTconInfo *tcon;
 
         seq_printf(m,
@@ -307,44 +316,55 @@ static int cifs_stats_proc_show(struct seq_file *m, void *v)
                 GlobalCurrentXid, GlobalMaxActiveXid);
 
         i = 0;
-        read_lock(&GlobalSMBSeslock);
-        list_for_each(tmp, &GlobalTreeConnectionList) {
-                i++;
-                tcon = list_entry(tmp, struct cifsTconInfo, cifsConnectionList);
-                seq_printf(m, "\n%d) %s", i, tcon->treeName);
-                if (tcon->need_reconnect)
-                        seq_puts(m, "\tDISCONNECTED ");
-                seq_printf(m, "\nSMBs: %d Oplock Breaks: %d",
-                        atomic_read(&tcon->num_smbs_sent),
-                        atomic_read(&tcon->num_oplock_brks));
-                seq_printf(m, "\nReads:  %d Bytes: %lld",
-                        atomic_read(&tcon->num_reads),
-                        (long long)(tcon->bytes_read));
-                seq_printf(m, "\nWrites: %d Bytes: %lld",
-                        atomic_read(&tcon->num_writes),
-                        (long long)(tcon->bytes_written));
-                seq_printf(m,
-                        "\nLocks: %d HardLinks: %d Symlinks: %d",
-                        atomic_read(&tcon->num_locks),
-                        atomic_read(&tcon->num_hardlinks),
-                        atomic_read(&tcon->num_symlinks));
-
-                seq_printf(m, "\nOpens: %d Closes: %d Deletes: %d",
-                        atomic_read(&tcon->num_opens),
-                        atomic_read(&tcon->num_closes),
-                        atomic_read(&tcon->num_deletes));
-                seq_printf(m, "\nMkdirs: %d Rmdirs: %d",
-                        atomic_read(&tcon->num_mkdirs),
-                        atomic_read(&tcon->num_rmdirs));
-                seq_printf(m, "\nRenames: %d T2 Renames %d",
-                        atomic_read(&tcon->num_renames),
-                        atomic_read(&tcon->num_t2renames));
-                seq_printf(m, "\nFindFirst: %d FNext %d FClose %d",
-                        atomic_read(&tcon->num_ffirst),
-                        atomic_read(&tcon->num_fnext),
-                        atomic_read(&tcon->num_fclose));
+        read_lock(&cifs_tcp_ses_lock);
+        list_for_each(tmp1, &cifs_tcp_ses_list) {
+                server = list_entry(tmp1, struct TCP_Server_Info,
+                                    tcp_ses_list);
+                list_for_each(tmp2, &server->smb_ses_list) {
+                        ses = list_entry(tmp2, struct cifsSesInfo,
+                                         smb_ses_list);
+                        list_for_each(tmp3, &ses->tcon_list) {
+                                tcon = list_entry(tmp3,
+                                                  struct cifsTconInfo,
+                                                  tcon_list);
+                                i++;
+                                seq_printf(m, "\n%d) %s", i, tcon->treeName);
+                                if (tcon->need_reconnect)
+                                        seq_puts(m, "\tDISCONNECTED ");
+                                seq_printf(m, "\nSMBs: %d Oplock Breaks: %d",
+                                        atomic_read(&tcon->num_smbs_sent),
+                                        atomic_read(&tcon->num_oplock_brks));
+                                seq_printf(m, "\nReads:  %d Bytes: %lld",
+                                        atomic_read(&tcon->num_reads),
+                                        (long long)(tcon->bytes_read));
+                                seq_printf(m, "\nWrites: %d Bytes: %lld",
+                                        atomic_read(&tcon->num_writes),
+                                        (long long)(tcon->bytes_written));
+                                seq_printf(m, "\nLocks: %d HardLinks: %d "
+                                              "Symlinks: %d",
+                                        atomic_read(&tcon->num_locks),
+                                        atomic_read(&tcon->num_hardlinks),
+                                        atomic_read(&tcon->num_symlinks));
+                                seq_printf(m, "\nOpens: %d Closes: %d"
+                                              "Deletes: %d",
+                                        atomic_read(&tcon->num_opens),
+                                        atomic_read(&tcon->num_closes),
+                                        atomic_read(&tcon->num_deletes));
+                                seq_printf(m, "\nMkdirs: %d Rmdirs: %d",
+                                        atomic_read(&tcon->num_mkdirs),
+                                        atomic_read(&tcon->num_rmdirs));
+                                seq_printf(m, "\nRenames: %d T2 Renames %d",
+                                        atomic_read(&tcon->num_renames),
+                                        atomic_read(&tcon->num_t2renames));
+                                seq_printf(m, "\nFindFirst: %d FNext %d "
+                                              "FClose %d",
+                                        atomic_read(&tcon->num_ffirst),
+                                        atomic_read(&tcon->num_fnext),
+                                        atomic_read(&tcon->num_fclose));
+                        }
+                }
         }
-        read_unlock(&GlobalSMBSeslock);
+        read_unlock(&cifs_tcp_ses_lock);
 
         seq_putc(m, '\n');
         return 0;
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index a1e96620b097..d9cf467309e8 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -514,10 +514,11 @@ static void cifs_umount_begin(struct super_block *sb)
         tcon = cifs_sb->tcon;
         if (tcon == NULL)
                 return;
-        down(&tcon->tconSem);
-        if (atomic_read(&tcon->useCount) == 1)
+
+        read_lock(&cifs_tcp_ses_lock);
+        if (tcon->tc_count == 1)
                 tcon->tidStatus = CifsExiting;
-        up(&tcon->tconSem);
+        read_unlock(&cifs_tcp_ses_lock);
 
         /* cancel_brl_requests(tcon); */ /* BB mark all brl mids as exiting */
         /* cancel_notify_requests(tcon); */
@@ -1060,7 +1061,6 @@ init_cifs(void)
         int rc = 0;
         cifs_proc_init();
         INIT_LIST_HEAD(&cifs_tcp_ses_list);
-        INIT_LIST_HEAD(&GlobalTreeConnectionList); /* BB to be removed by jl */
         INIT_LIST_HEAD(&GlobalOplock_Q);
 #ifdef CONFIG_CIFS_EXPERIMENTAL
         INIT_LIST_HEAD(&GlobalDnotifyReqList);
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;
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 9c95617baa4d..e6bb2d9d5b09 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -742,50 +742,31 @@ CIFSSMBTDis(const int xid, struct cifsTconInfo *tcon)
         int rc = 0;
 
         cFYI(1, ("In tree disconnect"));
-        /*
-         *  If last user of the connection and
-         *  connection alive - disconnect it
-         *  If this is the last connection on the server session disconnect it
-         *  (and inside session disconnect we should check if tcp socket needs
-         *  to be freed and kernel thread woken up).
-         */
-        if (tcon)
-                down(&tcon->tconSem);
-        else
-                return -EIO;
 
-        atomic_dec(&tcon->useCount);
-        if (atomic_read(&tcon->useCount) > 0) {
-                up(&tcon->tconSem);
-                return -EBUSY;
-        }
+        /* BB: do we need to check this? These should never be NULL. */
+        if ((tcon->ses == NULL) || (tcon->ses->server == NULL))
+                return -EIO;
 
-        /* No need to return error on this operation if tid invalidated and
-        closed on server already e.g. due to tcp session crashing */
-        if (tcon->need_reconnect) {
-                up(&tcon->tconSem);
+        /*
+         * No need to return error on this operation if tid invalidated and
+         * closed on server already e.g. due to tcp session crashing. Also,
+         * the tcon is no longer on the list, so no need to take lock before
+         * checking this.
+         */
+        if (tcon->need_reconnect)
                 return 0;
-        }
 
-        if ((tcon->ses == NULL) || (tcon->ses->server == NULL)) {
-                up(&tcon->tconSem);
-                return -EIO;
-        }
         rc = small_smb_init(SMB_COM_TREE_DISCONNECT, 0, tcon,
                             (void **)&smb_buffer);
-        if (rc) {
-                up(&tcon->tconSem);
+        if (rc)
                 return rc;
-        }
 
         rc = SendReceiveNoRsp(xid, tcon->ses, smb_buffer, 0);
         if (rc)
                 cFYI(1, ("Tree disconnect failed %d", rc));
 
-        up(&tcon->tconSem);
-
         /* No need to return error on this operation if tid invalidated and
-        closed on server already e.g. due to tcp session crashing */
+           closed on server already e.g. due to tcp session crashing */
         if (rc == -EAGAIN)
                 rc = 0;
 
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index a3dc0d7cafc3..2f2be8faabb3 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -124,7 +124,7 @@ static int
 cifs_reconnect(struct TCP_Server_Info *server)
 {
         int rc = 0;
-        struct list_head *tmp;
+        struct list_head *tmp, *tmp2;
         struct cifsSesInfo *ses;
         struct cifsTconInfo *tcon;
         struct mid_q_entry *mid_entry;
@@ -149,13 +149,12 @@ cifs_reconnect(struct TCP_Server_Info *server)
                 ses = list_entry(tmp, struct cifsSesInfo, smb_ses_list);
                 ses->need_reconnect = true;
                 ses->ipc_tid = 0;
-        }
-        read_unlock(&cifs_tcp_ses_lock);
-        list_for_each(tmp, &GlobalTreeConnectionList) {
-                tcon = list_entry(tmp, struct cifsTconInfo, cifsConnectionList);
-                if ((tcon->ses) && (tcon->ses->server == server))
+                list_for_each(tmp2, &ses->tcon_list) {
+                        tcon = list_entry(tmp2, struct cifsTconInfo, tcon_list);
                         tcon->need_reconnect = true;
+                }
         }
+        read_unlock(&cifs_tcp_ses_lock);
         /* do not want to be sending data on a socket we are freeing */
         down(&server->tcpSem);
         if (server->ssocket) {
@@ -1462,6 +1461,52 @@ cifs_put_smb_ses(struct cifsSesInfo *ses)
         cifs_put_tcp_session(server);
 }
 
+static struct cifsTconInfo *
+cifs_find_tcon(struct cifsSesInfo *ses, const char *unc)
+{
+        struct list_head *tmp;
+        struct cifsTconInfo *tcon;
+
+        write_lock(&cifs_tcp_ses_lock);
+        list_for_each(tmp, &ses->tcon_list) {
+                tcon = list_entry(tmp, struct cifsTconInfo, tcon_list);
+                if (tcon->tidStatus == CifsExiting)
+                        continue;
+                if (strncmp(tcon->treeName, unc, MAX_TREE_SIZE))
+                        continue;
+
+                ++tcon->tc_count;
+                write_unlock(&cifs_tcp_ses_lock);
+                return tcon;
+        }
+        write_unlock(&cifs_tcp_ses_lock);
+        return NULL;
+}
+
+static void
+cifs_put_tcon(struct cifsTconInfo *tcon)
+{
+        int xid;
+        struct cifsSesInfo *ses = tcon->ses;
+
+        write_lock(&cifs_tcp_ses_lock);
+        if (--tcon->tc_count > 0) {
+                write_unlock(&cifs_tcp_ses_lock);
+                return;
+        }
+
+        list_del_init(&tcon->tcon_list);
+        write_unlock(&cifs_tcp_ses_lock);
+
+        xid = GetXid();
+        CIFSSMBTDis(xid, tcon);
+        _FreeXid(xid);
+
+        DeleteTconOplockQEntries(tcon);
+        tconInfoFree(tcon);
+        cifs_put_smb_ses(ses);
+}
+
 int
 get_dfs_path(int xid, struct cifsSesInfo *pSesInfo, const char *old_path,
              const struct nls_table *nls_codepage, unsigned int *pnum_referrals,
@@ -2220,11 +2265,11 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
         if (!rc) {
                 setup_cifs_sb(&volume_info, cifs_sb);
 
+                tcon = cifs_find_tcon(pSesInfo, volume_info.UNC);
                 if (tcon) {
                         cFYI(1, ("Found match on UNC path"));
-                        if (tcon->seal != volume_info.seal)
-                                cERROR(1, ("transport encryption setting "
-                                           "conflicts with existing tid"));
+                        /* existing tcon already has a reference */
+                        cifs_put_smb_ses(pSesInfo);
                 } else {
                         tcon = tconInfoAlloc();
                         if (tcon == NULL) {
@@ -2257,6 +2302,10 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
                         if (rc)
                                 goto mount_fail_check;
                         tcon->seal = volume_info.seal;
+                        tcon->ses = pSesInfo;
+                        write_lock(&cifs_tcp_ses_lock);
+                        list_add(&tcon->tcon_list, &pSesInfo->tcon_list);
+                        write_unlock(&cifs_tcp_ses_lock);
                 }
 
                 /* we can have only one retry value for a connection
@@ -2283,18 +2332,14 @@ mount_fail_check:
                 /* If find_unc succeeded then rc == 0 so we can not end */
                 /* up accidently freeing someone elses tcon struct */
                 if (tcon)
-                        tconInfoFree(tcon);
-
-                /* should also end up putting our tcp session ref if needed */
-                if (pSesInfo)
+                        cifs_put_tcon(tcon);
+                else if (pSesInfo)
                         cifs_put_smb_ses(pSesInfo);
                 else
                         cifs_put_tcp_session(srvTcp);
                 goto out;
         }
-        atomic_inc(&tcon->useCount);
         cifs_sb->tcon = tcon;
-        tcon->ses = pSesInfo;
 
         /* do not care if following two calls succeed - informational */
         if (!tcon->ipc) {
@@ -3565,23 +3610,10 @@ int
 cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
 {
         int rc = 0;
-        int xid;
-        struct cifsSesInfo *ses = NULL;
         char *tmp;
 
-        xid = GetXid();
-
-        if (cifs_sb->tcon) {
-                ses = cifs_sb->tcon->ses; /* save ptr to ses before delete tcon!*/
-                rc = CIFSSMBTDis(xid, cifs_sb->tcon);
-                if (rc == -EBUSY) {
-                        FreeXid(xid);
-                        return 0;
-                }
-                DeleteTconOplockQEntries(cifs_sb->tcon);
-                tconInfoFree(cifs_sb->tcon);
-                cifs_put_smb_ses(ses);
-        }
+        if (cifs_sb->tcon)
+                cifs_put_tcon(cifs_sb->tcon);
 
         cifs_sb->tcon = NULL;
         tmp = cifs_sb->prepath;
@@ -3589,7 +3621,6 @@ cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
         cifs_sb->prepath = NULL;
         kfree(tmp);
 
-        FreeXid(xid);
         return rc;
 }
 
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 46c8c7baccba..addd1dcc2d79 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -79,6 +79,7 @@ sesInfoAlloc(void)
                 ret_buf->status = CifsNew;
                 ++ret_buf->ses_count;
                 INIT_LIST_HEAD(&ret_buf->smb_ses_list);
+                INIT_LIST_HEAD(&ret_buf->tcon_list);
                 init_MUTEX(&ret_buf->sesSem);
         }
         return ret_buf;
@@ -107,17 +108,14 @@ tconInfoAlloc(void)
         struct cifsTconInfo *ret_buf;
         ret_buf = kzalloc(sizeof(struct cifsTconInfo), GFP_KERNEL);
         if (ret_buf) {
-                write_lock(&GlobalSMBSeslock);
                 atomic_inc(&tconInfoAllocCount);
-                list_add(&ret_buf->cifsConnectionList,
-                         &GlobalTreeConnectionList);
                 ret_buf->tidStatus = CifsNew;
+                ++ret_buf->tc_count;
                 INIT_LIST_HEAD(&ret_buf->openFileList);
-                init_MUTEX(&ret_buf->tconSem);
+                INIT_LIST_HEAD(&ret_buf->tcon_list);
 #ifdef CONFIG_CIFS_STATS
                 spin_lock_init(&ret_buf->stat_lock);
 #endif
-                write_unlock(&GlobalSMBSeslock);
         }
         return ret_buf;
 }
@@ -129,10 +127,7 @@ tconInfoFree(struct cifsTconInfo *buf_to_free)
                 cFYI(1, ("Null buffer passed to tconInfoFree"));
                 return;
         }
-        write_lock(&GlobalSMBSeslock);
         atomic_dec(&tconInfoAllocCount);
-        list_del(&buf_to_free->cifsConnectionList);
-        write_unlock(&GlobalSMBSeslock);
         kfree(buf_to_free->nativeFileSystem);
         kfree(buf_to_free);
 }
@@ -493,9 +488,10 @@ bool
 is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
 {
         struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
-        struct list_head *tmp;
-        struct list_head *tmp1;
+        struct list_head *tmp, *tmp1, *tmp2;
+        struct cifsSesInfo *ses;
         struct cifsTconInfo *tcon;
+        struct cifsInodeInfo *pCifsInode;
         struct cifsFileInfo *netfile;
 
         cFYI(1, ("Checking for oplock break or dnotify response"));
@@ -550,42 +546,42 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
                 return false;
 
         /* look up tcon based on tid & uid */
-        read_lock(&GlobalSMBSeslock);
-        list_for_each(tmp, &GlobalTreeConnectionList) {
-                tcon = list_entry(tmp, struct cifsTconInfo, cifsConnectionList);
-                if ((tcon->tid == buf->Tid) && (srv == tcon->ses->server)) {
+        read_lock(&cifs_tcp_ses_lock);
+        list_for_each(tmp, &srv->smb_ses_list) {
+                ses = list_entry(tmp, struct cifsSesInfo, smb_ses_list);
+                list_for_each(tmp1, &ses->tcon_list) {
+                        tcon = list_entry(tmp1, struct cifsTconInfo, tcon_list);
+                        if (tcon->tid != buf->Tid)
+                                continue;
+
                         cifs_stats_inc(&tcon->num_oplock_brks);
-                        list_for_each(tmp1, &tcon->openFileList) {
-                                netfile = list_entry(tmp1, struct cifsFileInfo,
+                        list_for_each(tmp2, &tcon->openFileList) {
+                                netfile = list_entry(tmp2, struct cifsFileInfo,
                                                      tlist);
-                                if (pSMB->Fid == netfile->netfid) {
-                                        struct cifsInodeInfo *pCifsInode;
-                                        read_unlock(&GlobalSMBSeslock);
-                                        cFYI(1,
-                                            ("file id match, oplock break"));
-                                        pCifsInode =
-                                                CIFS_I(netfile->pInode);
-                                        pCifsInode->clientCanCacheAll = false;
-                                        if (pSMB->OplockLevel == 0)
-                                                pCifsInode->clientCanCacheRead
-                                                        = false;
-                                        pCifsInode->oplockPending = true;
-                                        AllocOplockQEntry(netfile->pInode,
-                                                          netfile->netfid,
-                                                          tcon);
-                                        cFYI(1,
-                                            ("about to wake up oplock thread"));
-                                        if (oplockThread)
-                                            wake_up_process(oplockThread);
-                                        return true;
-                                }
+                                if (pSMB->Fid != netfile->netfid)
+                                        continue;
+
+                                read_unlock(&cifs_tcp_ses_lock);
+                                cFYI(1, ("file id match, oplock break"));
+                                pCifsInode = CIFS_I(netfile->pInode);
+                                pCifsInode->clientCanCacheAll = false;
+                                if (pSMB->OplockLevel == 0)
+                                        pCifsInode->clientCanCacheRead = false;
+                                pCifsInode->oplockPending = true;
+                                AllocOplockQEntry(netfile->pInode,
+                                                  netfile->netfid, tcon);
+                                cFYI(1, ("about to wake up oplock thread"));
+                                if (oplockThread)
+                                        wake_up_process(oplockThread);
+
+                                return true;
                         }
-                        read_unlock(&GlobalSMBSeslock);
+                        read_unlock(&cifs_tcp_ses_lock);
                         cFYI(1, ("No matching file for oplock break"));
                         return true;
                 }
         }
-        read_unlock(&GlobalSMBSeslock);
+        read_unlock(&cifs_tcp_ses_lock);
         cFYI(1, ("Can not process oplock break for non-existent connection"));
         return true;
 }