cifs: allow for different handling of received response

In order to incorporate async requests, we need to allow for a more
general way to do things on receive, rather than just waking up a
process.

Turn the task pointer in the mid_q_entry into a callback function and a
generic data pointer. When a response comes in, or the socket is
reconnected, cifsd can call the callback function in order to wake up
the process.

The default is to just wake up the current process which should mean no
change in behavior for existing code.

Also, clean up the locking in cifs_reconnect. There doesn't seem to be
any need to hold both the srv_mutex and GlobalMid_Lock when walking the
list of mids.

Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 6abd1445c983..d77b6154cf22 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -36,6 +36,12 @@
 
 extern mempool_t *cifs_mid_poolp;
 
+static void
+wake_up_task(struct mid_q_entry *mid)
+{
+        wake_up_process(mid->callback_data);
+}
+
 static struct mid_q_entry *
 AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
 {
@@ -58,7 +64,13 @@ AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
         /*      do_gettimeofday(&temp->when_sent);*/ /* easier to use jiffies */
                 /* when mid allocated can be before when sent */
                 temp->when_alloc = jiffies;
-                temp->tsk = current;
+
+                /*
+                 * The default is for the mid to be synchronous, so the
+                 * default callback just wakes up the current task.
+                 */
+                temp->callback = wake_up_task;
+                temp->callback_data = current;
         }
 
         atomic_inc(&midCount);
@@ -367,6 +379,9 @@ sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
                 mid->mid, mid->midState);
 
         spin_lock(&GlobalMid_Lock);
+        /* ensure that it's no longer on the pending_mid_q */
+        list_del_init(&mid->qhead);
+
         switch (mid->midState) {
         case MID_RESPONSE_RECEIVED:
                 spin_unlock(&GlobalMid_Lock);
@@ -389,7 +404,7 @@ sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
         }
         spin_unlock(&GlobalMid_Lock);
 
-        delete_mid(mid);
+        DeleteMidQEntry(mid);
         return rc;
 }