cifs: reinstate sharing of SMB sessions sans races
We do this by abandoning the global list of SMB sessions and instead
moving to a per-server list. This entails adding a new list head to the
TCP_Server_Info struct. The refcounting for the cifsSesInfo is moved to
a non-atomic variable. We have to protect it by a lock anyway, so there's
no benefit to making it an atomic. The list and refcount are protected
by the global cifs_tcp_ses_lock.
The patch also adds a new routines to find and put SMB sessions and
that properly take and put references under the lock.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 88786ba..46c8c7b 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -75,12 +75,11 @@
ret_buf = kzalloc(sizeof(struct cifsSesInfo), GFP_KERNEL);
if (ret_buf) {
- write_lock(&GlobalSMBSeslock);
atomic_inc(&sesInfoAllocCount);
ret_buf->status = CifsNew;
- list_add(&ret_buf->cifsSessionList, &GlobalSMBSessionList);
+ ++ret_buf->ses_count;
+ INIT_LIST_HEAD(&ret_buf->smb_ses_list);
init_MUTEX(&ret_buf->sesSem);
- write_unlock(&GlobalSMBSeslock);
}
return ret_buf;
}
@@ -93,10 +92,7 @@
return;
}
- write_lock(&GlobalSMBSeslock);
atomic_dec(&sesInfoAllocCount);
- list_del(&buf_to_free->cifsSessionList);
- write_unlock(&GlobalSMBSeslock);
kfree(buf_to_free->serverOS);
kfree(buf_to_free->serverDomain);
kfree(buf_to_free->serverNOS);
@@ -350,9 +346,9 @@
if (current->fsuid != treeCon->ses->linux_uid) {
cFYI(1, ("Multiuser mode and UID "
"did not match tcon uid"));
- read_lock(&GlobalSMBSeslock);
- list_for_each(temp_item, &GlobalSMBSessionList) {
- ses = list_entry(temp_item, struct cifsSesInfo, cifsSessionList);
+ read_lock(&cifs_tcp_ses_lock);
+ list_for_each(temp_item, &treeCon->ses->server->smb_ses_list) {
+ ses = list_entry(temp_item, struct cifsSesInfo, smb_ses_list);
if (ses->linux_uid == current->fsuid) {
if (ses->server == treeCon->ses->server) {
cFYI(1, ("found matching uid substitute right smb_uid"));
@@ -364,7 +360,7 @@
}
}
}
- read_unlock(&GlobalSMBSeslock);
+ read_unlock(&cifs_tcp_ses_lock);
}
}
}