cifs: move mid finding into separate routine

Begin breaking up find_cifs_mid into smaller pieces. The parts that
coalesce T2 responses don't really need to be done under the
GlobalMid_lock anyway. Create a new function that just finds the
mid on the list, and then later takes it off the list if the entire
response has been received.

Reviewed-and-Tested-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Jeff Layton <jlayton@redhat.com>

1 files changed, 66 insertions, 47 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 5308bc6e1248..0f69b311d3fc 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -542,61 +542,80 @@ is_smb_response(struct TCP_Server_Info *server, unsigned char type)
 }
 
 static struct mid_q_entry *
-find_cifs_mid(struct TCP_Server_Info *server, struct smb_hdr *buf,
-              int *length, bool is_large_buf, bool *is_multi_rsp, char **bigbuf)
+find_mid(struct TCP_Server_Info *server, struct smb_hdr *buf)
 {
-        struct mid_q_entry *mid = NULL, *tmp_mid, *ret = NULL;
+        struct mid_q_entry *mid;
 
         spin_lock(&GlobalMid_Lock);
-        list_for_each_entry_safe(mid, tmp_mid, &server->pending_mid_q, qhead) {
-                if (mid->mid != buf->Mid ||
-                    mid->midState != MID_REQUEST_SUBMITTED ||
-                    mid->command != buf->Command)
-                        continue;
-
-                if (*length == 0 && check2ndT2(buf) > 0) {
-                        /* We have a multipart transact2 resp */
-                        *is_multi_rsp = true;
-                        if (mid->resp_buf) {
-                                /* merge response - fix up 1st*/
-                                *length = coalesce_t2(buf, mid->resp_buf);
-                                if (*length > 0) {
-                                        *length = 0;
-                                        mid->multiRsp = true;
-                                        break;
-                                }
-                                /* All parts received or packet is malformed. */
-                                mid->multiEnd = true;
-                                goto multi_t2_fnd;
-                        }
-                        if (!is_large_buf) {
-                                /*FIXME: switch to already allocated largebuf?*/
-                                cERROR(1, "1st trans2 resp needs bigbuf");
-                        } else {
-                                /* Have first buffer */
-                                mid->resp_buf = buf;
-                                mid->largeBuf = true;
-                                *bigbuf = NULL;
-                        }
-                        break;
+        list_for_each_entry(mid, &server->pending_mid_q, qhead) {
+                if (mid->mid == buf->Mid &&
+                    mid->midState == MID_REQUEST_SUBMITTED &&
+                    mid->command == buf->Command) {
+                        spin_unlock(&GlobalMid_Lock);
+                        return mid;
                 }
-                mid->resp_buf = buf;
-                mid->largeBuf = is_large_buf;
-multi_t2_fnd:
-                if (*length == 0)
-                        mid->midState = MID_RESPONSE_RECEIVED;
-                else
-                        mid->midState = MID_RESPONSE_MALFORMED;
+        }
+        spin_unlock(&GlobalMid_Lock);
+        return NULL;
+}
+
+static void
+dequeue_mid(struct mid_q_entry *mid, int malformed)
+{
 #ifdef CONFIG_CIFS_STATS2
-                mid->when_received = jiffies;
+        mid->when_received = jiffies;
 #endif
-                list_del_init(&mid->qhead);
-                ret = mid;
-                break;
-        }
+        spin_lock(&GlobalMid_Lock);
+        if (!malformed)
+                mid->midState = MID_RESPONSE_RECEIVED;
+        else
+                mid->midState = MID_RESPONSE_MALFORMED;
+        list_del_init(&mid->qhead);
         spin_unlock(&GlobalMid_Lock);
+}
 
-        return ret;
+static struct mid_q_entry *
+find_cifs_mid(struct TCP_Server_Info *server, struct smb_hdr *buf,
+              int *malformed, bool is_large_buf, bool *is_multi_rsp,
+              char **bigbuf)
+{
+        struct mid_q_entry *mid = NULL;
+
+        mid = find_mid(server, buf);
+        if (!mid)
+                return mid;
+
+        if (*malformed == 0 && check2ndT2(buf) > 0) {
+                /* We have a multipart transact2 resp */
+                *is_multi_rsp = true;
+                if (mid->resp_buf) {
+                        /* merge response - fix up 1st*/
+                        *malformed = coalesce_t2(buf, mid->resp_buf);
+                        if (*malformed > 0) {
+                                *malformed = 0;
+                                mid->multiRsp = true;
+                                return NULL;
+                        }
+                        /* All parts received or packet is malformed. */
+                        mid->multiEnd = true;
+                        goto multi_t2_fnd;
+                }
+                if (!is_large_buf) {
+                        /*FIXME: switch to already allocated largebuf?*/
+                        cERROR(1, "1st trans2 resp needs bigbuf");
+                } else {
+                        /* Have first buffer */
+                        mid->resp_buf = buf;
+                        mid->largeBuf = true;
+                        *bigbuf = NULL;
+                }
+                return mid;
+        }
+        mid->resp_buf = buf;
+        mid->largeBuf = is_large_buf;
+multi_t2_fnd:
+        dequeue_mid(mid, *malformed);
+        return mid;
 }
 
 static void clean_demultiplex_info(struct TCP_Server_Info *server)