cifs: Do not modify mid entry after submitting I/O in cifs_call_async

In cifs_call_async, server may respond as soon as I/O is submitted. Because
mid entry is freed on the return path, it should not be modified after I/O
is submitted.

cifs_save_when_sent modifies the sent timestamp in mid entry, and should not
be called after I/O. Call it before I/O.

Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 47a125e..7efbab0 100644 (file)
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -536,11 +536,14 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
        list_add_tail(&mid->qhead, &server->pending_mid_q);
        spin_unlock(&GlobalMid_Lock);
 
-
+       /*
+        * Need to store the time in mid before calling I/O. For call_async,
+        * I/O response may come back and free the mid entry on another thread.
+        */
+       cifs_save_when_sent(mid);
        cifs_in_send_inc(server);
        rc = smb_send_rqst(server, rqst, flags);
        cifs_in_send_dec(server);
-       cifs_save_when_sent(mid);
 
        if (rc < 0) {
                server->sequence_number -= 2;