CIFS: Move get_next_mid to ops struct

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>

7 files changed, 103 insertions, 95 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 20350a93ed99..6df0cbe1cbc9 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -174,6 +174,7 @@ struct smb_version_operations {
         void (*add_credits)(struct TCP_Server_Info *, const unsigned int);
         void (*set_credits)(struct TCP_Server_Info *, const int);
         int * (*get_credits_field)(struct TCP_Server_Info *);
+        __u64 (*get_next_mid)(struct TCP_Server_Info *);
         /* data offset from read response message */
         unsigned int (*read_data_offset)(char *);
         /* data length from read response message */
@@ -399,6 +400,12 @@ set_credits(struct TCP_Server_Info *server, const int val)
         server->ops->set_credits(server, val);
 }
 
+static inline __u64
+get_next_mid(struct TCP_Server_Info *server)
+{
+        return server->ops->get_next_mid(server);
+}
+
 /*
  * Macros to allow the TCP_Server_Info->net field and related code to drop out
  * when CONFIG_NET_NS isn't set.
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 5ec21ecf7980..0a6cbfe2761e 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -114,7 +114,6 @@ extern int small_smb_init_no_tc(const int smb_cmd, const int wct,
                                 void **request_buf);
 extern int CIFS_SessSetup(unsigned int xid, struct cifs_ses *ses,
                              const struct nls_table *nls_cp);
-extern __u64 GetNextMid(struct TCP_Server_Info *server);
 extern struct timespec cifs_NTtimeToUnix(__le64 utc_nanoseconds_since_1601);
 extern u64 cifs_UnixTimeToNT(struct timespec);
 extern struct timespec cnvrtDosUnixTm(__le16 le_date, __le16 le_time,
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index b5ad716b2642..5b400730c213 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -268,7 +268,7 @@ small_smb_init_no_tc(const int smb_command, const int wct,
                 return rc;
 
         buffer = (struct smb_hdr *)*request_buf;
-        buffer->Mid = GetNextMid(ses->server);
+        buffer->Mid = get_next_mid(ses->server);
         if (ses->capabilities & CAP_UNICODE)
                 buffer->Flags2 |= SMBFLG2_UNICODE;
         if (ses->capabilities & CAP_STATUS32)
@@ -402,7 +402,7 @@ CIFSSMBNegotiate(unsigned int xid, struct cifs_ses *ses)
 
         cFYI(1, "secFlags 0x%x", secFlags);
 
-        pSMB->hdr.Mid = GetNextMid(server);
+        pSMB->hdr.Mid = get_next_mid(server);
         pSMB->hdr.Flags2 |= (SMBFLG2_UNICODE | SMBFLG2_ERR_STATUS);
 
         if ((secFlags & CIFSSEC_MUST_KRB5) == CIFSSEC_MUST_KRB5)
@@ -782,7 +782,7 @@ CIFSSMBLogoff(const int xid, struct cifs_ses *ses)
                 return rc;
         }
 
-        pSMB->hdr.Mid = GetNextMid(ses->server);
+        pSMB->hdr.Mid = get_next_mid(ses->server);
 
         if (ses->server->sec_mode &
                    (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED))
@@ -4762,7 +4762,7 @@ getDFSRetry:
 
         /* server pointer checked in called function,
         but should never be null here anyway */
-        pSMB->hdr.Mid = GetNextMid(ses->server);
+        pSMB->hdr.Mid = get_next_mid(ses->server);
         pSMB->hdr.Tid = ses->ipc_tid;
         pSMB->hdr.Uid = ses->Suid;
         if (ses->capabilities & CAP_STATUS32)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 3647b1a4540b..78db68a5cf44 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3940,7 +3940,7 @@ CIFSTCon(unsigned int xid, struct cifs_ses *ses,
         header_assemble(smb_buffer, SMB_COM_TREE_CONNECT_ANDX,
                         NULL /*no tid */ , 4 /*wct */ );
 
-        smb_buffer->Mid = GetNextMid(ses->server);
+        smb_buffer->Mid = get_next_mid(ses->server);
         smb_buffer->Uid = ses->Suid;
         pSMB = (TCONX_REQ *) smb_buffer;
         pSMBr = (TCONX_RSP *) smb_buffer_response;
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index e2552d2b2e42..557506ae1e2a 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -212,93 +212,6 @@ cifs_small_buf_release(void *buf_to_free)
         return;
 }
 
-/*
- * Find a free multiplex id (SMB mid). Otherwise there could be
- * mid collisions which might cause problems, demultiplexing the
- * wrong response to this request. Multiplex ids could collide if
- * one of a series requests takes much longer than the others, or
- * if a very large number of long lived requests (byte range
- * locks or FindNotify requests) are pending. No more than
- * 64K-1 requests can be outstanding at one time. If no
- * mids are available, return zero. A future optimization
- * could make the combination of mids and uid the key we use
- * to demultiplex on (rather than mid alone).
- * In addition to the above check, the cifs demultiplex
- * code already used the command code as a secondary
- * check of the frame and if signing is negotiated the
- * response would be discarded if the mid were the same
- * but the signature was wrong. Since the mid is not put in the
- * pending queue until later (when it is about to be dispatched)
- * we do have to limit the number of outstanding requests
- * to somewhat less than 64K-1 although it is hard to imagine
- * so many threads being in the vfs at one time.
- */
-__u64 GetNextMid(struct TCP_Server_Info *server)
-{
-        __u64 mid = 0;
-        __u16 last_mid, cur_mid;
-        bool collision;
-
-        spin_lock(&GlobalMid_Lock);
-
-        /* mid is 16 bit only for CIFS/SMB */
-        cur_mid = (__u16)((server->CurrentMid) & 0xffff);
-        /* we do not want to loop forever */
-        last_mid = cur_mid;
-        cur_mid++;
-
-        /*
-         * This nested loop looks more expensive than it is.
-         * In practice the list of pending requests is short,
-         * fewer than 50, and the mids are likely to be unique
-         * on the first pass through the loop unless some request
-         * takes longer than the 64 thousand requests before it
-         * (and it would also have to have been a request that
-         * did not time out).
-         */
-        while (cur_mid != last_mid) {
-                struct mid_q_entry *mid_entry;
-                unsigned int num_mids;
-
-                collision = false;
-                if (cur_mid == 0)
-                        cur_mid++;
-
-                num_mids = 0;
-                list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) {
-                        ++num_mids;
-                        if (mid_entry->mid == cur_mid &&
-                            mid_entry->mid_state == MID_REQUEST_SUBMITTED) {
-                                /* This mid is in use, try a different one */
-                                collision = true;
-                                break;
-                        }
-                }
-
-                /*
-                 * if we have more than 32k mids in the list, then something
-                 * is very wrong. Possibly a local user is trying to DoS the
-                 * box by issuing long-running calls and SIGKILL'ing them. If
-                 * we get to 2^16 mids then we're in big trouble as this
-                 * function could loop forever.
-                 *
-                 * Go ahead and assign out the mid in this situation, but force
-                 * an eventual reconnect to clean out the pending_mid_q.
-                 */
-                if (num_mids > 32768)
-                        server->tcpStatus = CifsNeedReconnect;
-
-                if (!collision) {
-                        mid = (__u64)cur_mid;
-                        server->CurrentMid = mid;
-                        break;
-                }
-                cur_mid++;
-        }
-        spin_unlock(&GlobalMid_Lock);
-        return mid;
-}
-
 /* NB: MID can not be set if treeCon not passed in, in that
    case it is responsbility of caller to set the mid */
 void
@@ -334,7 +247,7 @@ header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
 
                         /* Uid is not converted */
                         buffer->Uid = treeCon->ses->Suid;
-                        buffer->Mid = GetNextMid(treeCon->ses->server);
+                        buffer->Mid = get_next_mid(treeCon->ses->server);
                 }
                 if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
                         buffer->Flags2 |= SMBFLG2_DFS;
diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c
index d9d615fbed3f..6dec38f5522d 100644
--- a/fs/cifs/smb1ops.c
+++ b/fs/cifs/smb1ops.c
@@ -125,6 +125,94 @@ cifs_get_credits_field(struct TCP_Server_Info *server)
         return &server->credits;
 }
 
+/*
+ * Find a free multiplex id (SMB mid). Otherwise there could be
+ * mid collisions which might cause problems, demultiplexing the
+ * wrong response to this request. Multiplex ids could collide if
+ * one of a series requests takes much longer than the others, or
+ * if a very large number of long lived requests (byte range
+ * locks or FindNotify requests) are pending. No more than
+ * 64K-1 requests can be outstanding at one time. If no
+ * mids are available, return zero. A future optimization
+ * could make the combination of mids and uid the key we use
+ * to demultiplex on (rather than mid alone).
+ * In addition to the above check, the cifs demultiplex
+ * code already used the command code as a secondary
+ * check of the frame and if signing is negotiated the
+ * response would be discarded if the mid were the same
+ * but the signature was wrong. Since the mid is not put in the
+ * pending queue until later (when it is about to be dispatched)
+ * we do have to limit the number of outstanding requests
+ * to somewhat less than 64K-1 although it is hard to imagine
+ * so many threads being in the vfs at one time.
+ */
+static __u64
+cifs_get_next_mid(struct TCP_Server_Info *server)
+{
+        __u64 mid = 0;
+        __u16 last_mid, cur_mid;
+        bool collision;
+
+        spin_lock(&GlobalMid_Lock);
+
+        /* mid is 16 bit only for CIFS/SMB */
+        cur_mid = (__u16)((server->CurrentMid) & 0xffff);
+        /* we do not want to loop forever */
+        last_mid = cur_mid;
+        cur_mid++;
+
+        /*
+         * This nested loop looks more expensive than it is.
+         * In practice the list of pending requests is short,
+         * fewer than 50, and the mids are likely to be unique
+         * on the first pass through the loop unless some request
+         * takes longer than the 64 thousand requests before it
+         * (and it would also have to have been a request that
+         * did not time out).
+         */
+        while (cur_mid != last_mid) {
+                struct mid_q_entry *mid_entry;
+                unsigned int num_mids;
+
+                collision = false;
+                if (cur_mid == 0)
+                        cur_mid++;
+
+                num_mids = 0;
+                list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) {
+                        ++num_mids;
+                        if (mid_entry->mid == cur_mid &&
+                            mid_entry->mid_state == MID_REQUEST_SUBMITTED) {
+                                /* This mid is in use, try a different one */
+                                collision = true;
+                                break;
+                        }
+                }
+
+                /*
+                 * if we have more than 32k mids in the list, then something
+                 * is very wrong. Possibly a local user is trying to DoS the
+                 * box by issuing long-running calls and SIGKILL'ing them. If
+                 * we get to 2^16 mids then we're in big trouble as this
+                 * function could loop forever.
+                 *
+                 * Go ahead and assign out the mid in this situation, but force
+                 * an eventual reconnect to clean out the pending_mid_q.
+                 */
+                if (num_mids > 32768)
+                        server->tcpStatus = CifsNeedReconnect;
+
+                if (!collision) {
+                        mid = (__u64)cur_mid;
+                        server->CurrentMid = mid;
+                        break;
+                }
+                cur_mid++;
+        }
+        spin_unlock(&GlobalMid_Lock);
+        return mid;
+}
+
 struct smb_version_operations smb1_operations = {
         .send_cancel = send_nt_cancel,
         .compare_fids = cifs_compare_fids,
@@ -133,6 +221,7 @@ struct smb_version_operations smb1_operations = {
         .add_credits = cifs_add_credits,
         .set_credits = cifs_set_credits,
         .get_credits_field = cifs_get_credits_field,
+        .get_next_mid = cifs_get_next_mid,
         .read_data_offset = cifs_read_data_offset,
         .read_data_length = cifs_read_data_length,
         .map_error = map_smb_to_linux_error,
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 1b36ffe6a47b..3097ee58fd7d 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -779,7 +779,7 @@ send_lock_cancel(const unsigned int xid, struct cifs_tcon *tcon,
 
         pSMB->LockType = LOCKING_ANDX_CANCEL_LOCK|LOCKING_ANDX_LARGE_FILES;
         pSMB->Timeout = 0;
-        pSMB->hdr.Mid = GetNextMid(ses->server);
+        pSMB->hdr.Mid = get_next_mid(ses->server);
 
         return SendReceive(xid, ses, in_buf, out_buf,
                         &bytes_returned, 0);