cifs: avoid use of global locks for high contention data

During analysis of multichannel perf, it was seen that
the global locks cifs_tcp_ses_lock and GlobalMid_Lock, which
were shared between various data structures were causing a
lot of contention points.

With this change, we're breaking down the use of these locks
by introducing new locks at more granular levels. i.e.
server->srv_lock, ses->ses_lock and tcon->tc_lock to protect
the unprotected fields of server, session and tcon structs;
and server->mid_lock to protect mid related lists and entries
at server level.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifs_debug.c

@@ -55,7 +55,7 @@ void cifs_dump_mids(struct TCP_Server_Info *server)
 		return;
 
 	cifs_dbg(VFS, "Dump pending requests:\n");
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) {
 		cifs_dbg(VFS, "State: %d Cmd: %d Pid: %d Cbdata: %p Mid %llu\n",
 			 mid_entry->mid_state,
@@ -78,7 +78,7 @@ void cifs_dump_mids(struct TCP_Server_Info *server)
 				mid_entry->resp_buf, 62);
 		}
 	}
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 #endif /* CONFIG_CIFS_DEBUG2 */
 }
 
@@ -463,7 +463,7 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 			seq_printf(m, "\n\t\t[NONE]");
 
 		seq_puts(m, "\n\n\tMIDs: ");
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&server->mid_lock);
 		list_for_each_entry(mid_entry, &server->pending_mid_q, qhead) {
 			seq_printf(m, "\n\tState: %d com: %d pid:"
 					" %d cbdata: %p mid %llu\n",
@@ -473,7 +473,7 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 					mid_entry->callback_data,
 					mid_entry->mid);
 		}
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&server->mid_lock);
 		seq_printf(m, "\n--\n");
 	}
 	if (c == 0)

fs/cifs/cifsencrypt.c

@@ -141,13 +141,13 @@ int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
 	if ((cifs_pdu == NULL) || (server == NULL))
 		return -EINVAL;
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) ||
 	    server->tcpStatus == CifsNeedNegotiate) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return rc;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	if (!server->session_estab) {
 		memcpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8);

fs/cifs/cifsfs.c

@@ -731,14 +731,17 @@ static void cifs_umount_begin(struct super_block *sb)
 	tcon = cifs_sb_master_tcon(cifs_sb);
 
 	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&tcon->tc_lock);
 	if ((tcon->tc_count > 1) || (tcon->status == TID_EXITING)) {
 		/* we have other mounts to same share or we have
 		   already tried to force umount this and woken up
 		   all waiting network requests, nothing to do */
+		spin_unlock(&tcon->tc_lock);
 		spin_unlock(&cifs_tcp_ses_lock);
 		return;
 	} else if (tcon->tc_count == 1)
 		tcon->status = TID_EXITING;
+	spin_unlock(&tcon->tc_lock);
 	spin_unlock(&cifs_tcp_ses_lock);
 
 	/* cancel_brl_requests(tcon); */ /* BB mark all brl mids as exiting */

fs/cifs/cifsglob.h

@@ -605,6 +605,7 @@ inc_rfc1001_len(void *buf, int count)
 struct TCP_Server_Info {
 	struct list_head tcp_ses_list;
 	struct list_head smb_ses_list;
+	spinlock_t srv_lock;  /* protect anything here that is not protected */
 	__u64 conn_id; /* connection identifier (useful for debugging) */
 	int srv_count; /* reference counter */
 	/* 15 character server name + 0x20 16th byte indicating type = srv */
@@ -622,6 +623,7 @@ struct TCP_Server_Info {
 #endif
 	wait_queue_head_t response_q;
 	wait_queue_head_t request_q; /* if more than maxmpx to srvr must block*/
+	spinlock_t mid_lock;  /* protect mid queue and it's entries */
 	struct list_head pending_mid_q;
 	bool noblocksnd;		/* use blocking sendmsg */
 	bool noautotune;		/* do not autotune send buf sizes */
@@ -1008,6 +1010,7 @@ struct cifs_ses {
 	struct list_head rlist; /* reconnect list */
 	struct list_head tcon_list;
 	struct cifs_tcon *tcon_ipc;
+	spinlock_t ses_lock;  /* protect anything here that is not protected */
 	struct mutex session_mutex;
 	struct TCP_Server_Info *server;	/* pointer to server info */
 	int ses_count;		/* reference counter */
@@ -1169,6 +1172,7 @@ struct cifs_tcon {
 	struct list_head tcon_list;
 	int tc_count;
 	struct list_head rlist; /* reconnect list */
+	spinlock_t tc_lock;  /* protect anything here that is not protected */
 	atomic_t num_local_opens;  /* num of all opens including disconnected */
 	atomic_t num_remote_opens; /* num of all network opens on server */
 	struct list_head openFileList;
@@ -1899,33 +1903,78 @@ require use of the stronger protocol */
  */
 
 /****************************************************************************
- *  Locking notes.  All updates to global variables and lists should be
- *                  protected by spinlocks or semaphores.
+ * Here are all the locks (spinlock, mutex, semaphore) in cifs.ko, arranged according
+ * to the locking order. i.e. if two locks are to be held together, the lock that
+ * appears higher in this list needs to be taken before the other.
  *
- *  Spinlocks
- *  ---------
- *  GlobalMid_Lock protects:
- *	list operations on pending_mid_q and oplockQ
- *      updates to XID counters, multiplex id  and SMB sequence numbers
- *      list operations on global DnotifyReqList
- *      updates to ses->status and TCP_Server_Info->tcpStatus
- *      updates to server->CurrentMid
- *  tcp_ses_lock protects:
- *	list operations on tcp and SMB session lists
- *  tcon->open_file_lock protects the list of open files hanging off the tcon
- *  inode->open_file_lock protects the openFileList hanging off the inode
- *  cfile->file_info_lock protects counters and fields in cifs file struct
- *  f_owner.lock protects certain per file struct operations
- *  mapping->page_lock protects certain per page operations
+ * If you hold a lock that is lower in this list, and you need to take a higher lock
+ * (or if you think that one of the functions that you're calling may need to), first
+ * drop the lock you hold, pick up the higher lock, then the lower one. This will
+ * ensure that locks are picked up only in one direction in the below table
+ * (top to bottom).
  *
- *  Note that the cifs_tcon.open_file_lock should be taken before
- *  not after the cifsInodeInfo.open_file_lock
+ * Also, if you expect a function to be called with a lock held, explicitly document
+ * this in the comments on top of your function definition.
  *
- *  Semaphores
- *  ----------
- *  cifsInodeInfo->lock_sem protects:
- *	the list of locks held by the inode
+ * And also, try to keep the critical sections (lock hold time) to be as minimal as
+ * possible. Blocking / calling other functions with a lock held always increase
+ * the risk of a possible deadlock.
  *
+ * Following this rule will avoid unnecessary deadlocks, which can get really hard to
+ * debug. Also, any new lock that you introduce, please add to this list in the correct
+ * order.
+ *
+ * Please populate this list whenever you introduce new locks in your changes. Or in
+ * case I've missed some existing locks. Please ensure that it's added in the list
+ * based on the locking order expected.
+ *
+ * =====================================================================================
+ * Lock				Protects			Initialization fn
+ * =====================================================================================
+ * vol_list_lock
+ * vol_info->ctx_lock		vol_info->ctx
+ * cifs_sb_info->tlink_tree_lock	cifs_sb_info->tlink_tree	cifs_setup_cifs_sb
+ * TCP_Server_Info->		TCP_Server_Info			cifs_get_tcp_session
+ * reconnect_mutex
+ * TCP_Server_Info->srv_mutex	TCP_Server_Info			cifs_get_tcp_session
+ * cifs_ses->session_mutex		cifs_ses		sesInfoAlloc
+ *				cifs_tcon
+ * cifs_tcon->open_file_lock	cifs_tcon->openFileList		tconInfoAlloc
+ *				cifs_tcon->pending_opens
+ * cifs_tcon->stat_lock		cifs_tcon->bytes_read		tconInfoAlloc
+ *				cifs_tcon->bytes_written
+ * cifs_tcp_ses_lock		cifs_tcp_ses_list		sesInfoAlloc
+ * GlobalMid_Lock		GlobalMaxActiveXid		init_cifs
+ *				GlobalCurrentXid
+ *				GlobalTotalActiveXid
+ * TCP_Server_Info->srv_lock	(anything in struct not protected by another lock and can change)
+ * TCP_Server_Info->mid_lock	TCP_Server_Info->pending_mid_q	cifs_get_tcp_session
+ *				->CurrentMid
+ *				(any changes in mid_q_entry fields)
+ * TCP_Server_Info->req_lock	TCP_Server_Info->in_flight	cifs_get_tcp_session
+ *				->credits
+ *				->echo_credits
+ *				->oplock_credits
+ *				->reconnect_instance
+ * cifs_ses->ses_lock		(anything that is not protected by another lock and can change)
+ * cifs_ses->iface_lock		cifs_ses->iface_list		sesInfoAlloc
+ *				->iface_count
+ *				->iface_last_update
+ * cifs_ses->chan_lock		cifs_ses->chans
+ *				->chans_need_reconnect
+ *				->chans_in_reconnect
+ * cifs_tcon->tc_lock		(anything that is not protected by another lock and can change)
+ * cifsInodeInfo->open_file_lock	cifsInodeInfo->openFileList	cifs_alloc_inode
+ * cifsInodeInfo->writers_lock	cifsInodeInfo->writers		cifsInodeInfo_alloc
+ * cifsInodeInfo->lock_sem	cifsInodeInfo->llist		cifs_init_once
+ *				->can_cache_brlcks
+ * cifsInodeInfo->deferred_lock	cifsInodeInfo->deferred_closes	cifsInodeInfo_alloc
+ * cached_fid->fid_mutex		cifs_tcon->crfid		tconInfoAlloc
+ * cifsFileInfo->fh_mutex		cifsFileInfo			cifs_new_fileinfo
+ * cifsFileInfo->file_info_lock	cifsFileInfo->count		cifs_new_fileinfo
+ *				->invalidHandle			initiate_cifs_search
+ *				->oplock_break_cancelled
+ * cifs_aio_ctx->aio_mutex		cifs_aio_ctx			cifs_aio_ctx_alloc
  ****************************************************************************/
 
 #ifdef DECLARE_GLOBALS_HERE
@@ -1946,9 +1995,7 @@ extern struct list_head		cifs_tcp_ses_list;
 /*
  * This lock protects the cifs_tcp_ses_list, the list of smb sessions per
  * tcp session, and the list of tcon's per smb session. It also protects
- * the reference counters for the server, smb session, and tcon. It also
- * protects some fields in the TCP_Server_Info struct such as dstaddr. Finally,
- * changes to the tcon->tidStatus should be done while holding this lock.
+ * the reference counters for the server, smb session, and tcon.
  * generally the locks should be taken in order tcp_ses_lock before
  * tcon->open_file_lock and that before file->file_info_lock since the
  * structure order is cifs_socket-->cifs_ses-->cifs_tcon-->cifs_file

fs/cifs/cifssmb.c

@@ -74,13 +74,13 @@ cifs_mark_open_files_invalid(struct cifs_tcon *tcon)
 	struct list_head *tmp1;
 
 	/* only send once per connect */
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&tcon->ses->ses_lock);
 	if ((tcon->ses->ses_status != SES_GOOD) || (tcon->status != TID_NEED_RECON)) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&tcon->ses->ses_lock);
 		return;
 	}
 	tcon->status = TID_IN_FILES_INVALIDATE;
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&tcon->ses->ses_lock);
 
 	/* list all files open on tree connection and mark them invalid */
 	spin_lock(&tcon->open_file_lock);
@@ -98,10 +98,10 @@ cifs_mark_open_files_invalid(struct cifs_tcon *tcon)
 	memset(tcon->crfid.fid, 0, sizeof(struct cifs_fid));
 	mutex_unlock(&tcon->crfid.fid_mutex);
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&tcon->tc_lock);
 	if (tcon->status == TID_IN_FILES_INVALIDATE)
 		tcon->status = TID_NEED_TCON;
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&tcon->tc_lock);
 
 	/*
 	 * BB Add call to invalidate_inodes(sb) for all superblocks mounted
@@ -134,18 +134,18 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	 * only tree disconnect, open, and write, (and ulogoff which does not
 	 * have tcon) are allowed as we start force umount
 	 */
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&tcon->tc_lock);
 	if (tcon->status == TID_EXITING) {
 		if (smb_command != SMB_COM_WRITE_ANDX &&
 		    smb_command != SMB_COM_OPEN_ANDX &&
 		    smb_command != SMB_COM_TREE_DISCONNECT) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&tcon->tc_lock);
 			cifs_dbg(FYI, "can not send cmd %d while umounting\n",
 				 smb_command);
 			return -ENODEV;
 		}
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&tcon->tc_lock);
 
 	retries = server->nr_targets;
 
@@ -165,12 +165,12 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		}
 
 		/* are we still trying to reconnect? */
-		spin_lock(&cifs_tcp_ses_lock);
+		spin_lock(&server->srv_lock);
 		if (server->tcpStatus != CifsNeedReconnect) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&server->srv_lock);
 			break;
 		}
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 
 		if (retries && --retries)
 			continue;
@@ -201,13 +201,13 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	 * and the server never sends an answer the socket will be closed
 	 * and tcpStatus set to reconnect.
 	 */
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		rc = -EHOSTDOWN;
 		goto out;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously

fs/cifs/dfs_cache.c

@@ -1526,15 +1526,21 @@ static void refresh_mounts(struct cifs_ses **sessions)
 
 	spin_lock(&cifs_tcp_ses_lock);
 	list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
-		if (!server->is_dfs_conn)
+		spin_lock(&server->srv_lock);
+		if (!server->is_dfs_conn) {
+			spin_unlock(&server->srv_lock);
 			continue;
+		}
+		spin_unlock(&server->srv_lock);
 
 		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
 			list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
+				spin_lock(&tcon->tc_lock);
 				if (!tcon->ipc && !tcon->need_reconnect) {
 					tcon->tc_count++;
 					list_add_tail(&tcon->ulist, &tcons);
 				}
+				spin_unlock(&tcon->tc_lock);
 			}
 		}
 	}

fs/cifs/misc.c

@@ -69,6 +69,7 @@ sesInfoAlloc(void)
 	ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
 	if (ret_buf) {
 		atomic_inc(&sesInfoAllocCount);
+		spin_lock_init(&ret_buf->ses_lock);
 		ret_buf->ses_status = SES_NEW;
 		++ret_buf->ses_count;
 		INIT_LIST_HEAD(&ret_buf->smb_ses_list);
@@ -126,6 +127,7 @@ tconInfoAlloc(void)
 	atomic_inc(&tconInfoAllocCount);
 	ret_buf->status = TID_NEW;
 	++ret_buf->tc_count;
+	spin_lock_init(&ret_buf->tc_lock);
 	INIT_LIST_HEAD(&ret_buf->openFileList);
 	INIT_LIST_HEAD(&ret_buf->tcon_list);
 	spin_lock_init(&ret_buf->open_file_lock);

fs/cifs/smb1ops.c

@@ -92,17 +92,17 @@ cifs_find_mid(struct TCP_Server_Info *server, char *buffer)
 	struct smb_hdr *buf = (struct smb_hdr *)buffer;
 	struct mid_q_entry *mid;
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	list_for_each_entry(mid, &server->pending_mid_q, qhead) {
 		if (compare_mid(mid->mid, buf) &&
 		    mid->mid_state == MID_REQUEST_SUBMITTED &&
 		    le16_to_cpu(mid->command) == buf->Command) {
 			kref_get(&mid->refcount);
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&server->mid_lock);
 			return mid;
 		}
 	}
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 	return NULL;
 }
 
@@ -166,7 +166,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 	__u16 last_mid, cur_mid;
 	bool collision, reconnect = false;
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 
 	/* mid is 16 bit only for CIFS/SMB */
 	cur_mid = (__u16)((server->CurrentMid) & 0xffff);
@@ -225,7 +225,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 		}
 		cur_mid++;
 	}
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 
 	if (reconnect) {
 		cifs_signal_cifsd_for_reconnect(server, false);

fs/cifs/smb2ops.c

@@ -126,13 +126,13 @@ smb2_add_credits(struct TCP_Server_Info *server,
 			 optype, scredits, add);
 	}
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsNeedReconnect
 	    || server->tcpStatus == CifsExiting) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	switch (rc) {
 	case -1:
@@ -218,12 +218,12 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 			spin_lock(&server->req_lock);
 		} else {
 			spin_unlock(&server->req_lock);
-			spin_lock(&cifs_tcp_ses_lock);
+			spin_lock(&server->srv_lock);
 			if (server->tcpStatus == CifsExiting) {
-				spin_unlock(&cifs_tcp_ses_lock);
+				spin_unlock(&server->srv_lock);
 				return -ENOENT;
 			}
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&server->srv_lock);
 
 			spin_lock(&server->req_lock);
 			scredits = server->credits;
@@ -319,19 +319,19 @@ smb2_get_next_mid(struct TCP_Server_Info *server)
 {
 	__u64 mid;
 	/* for SMB2 we need the current value */
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	mid = server->CurrentMid++;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 	return mid;
 }
 
 static void
 smb2_revert_current_mid(struct TCP_Server_Info *server, const unsigned int val)
 {
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	if (server->CurrentMid >= val)
 		server->CurrentMid -= val;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 }
 
 static struct mid_q_entry *
@@ -346,7 +346,7 @@ __smb2_find_mid(struct TCP_Server_Info *server, char *buf, bool dequeue)
 		return NULL;
 	}
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	list_for_each_entry(mid, &server->pending_mid_q, qhead) {
 		if ((mid->mid == wire_mid) &&
 		    (mid->mid_state == MID_REQUEST_SUBMITTED) &&
@@ -356,11 +356,11 @@ __smb2_find_mid(struct TCP_Server_Info *server, char *buf, bool dequeue)
 				list_del_init(&mid->qhead);
 				mid->mid_flags |= MID_DELETED;
 			}
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&server->mid_lock);
 			return mid;
 		}
 	}
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 	return NULL;
 }
 
@@ -403,9 +403,9 @@ smb2_negotiate(const unsigned int xid,
 {
 	int rc;
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	server->CurrentMid = 0;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 	rc = SMB2_negotiate(xid, ses, server);
 	/* BB we probably don't need to retry with modern servers */
 	if (rc == -EAGAIN)
@@ -2585,7 +2585,9 @@ smb2_is_network_name_deleted(char *buf, struct TCP_Server_Info *server)
 	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
 		list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 			if (tcon->tid == le32_to_cpu(shdr->Id.SyncId.TreeId)) {
+				spin_lock(&tcon->tc_lock);
 				tcon->need_reconnect = true;
+				spin_unlock(&tcon->tc_lock);
 				spin_unlock(&cifs_tcp_ses_lock);
 				pr_warn_once("Server share %s deleted.\n",
 					     tcon->treeName);
@@ -4561,9 +4563,11 @@ smb2_get_enc_key(struct TCP_Server_Info *server, __u64 ses_id, int enc, u8 *key)
 	list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
 		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
 			if (ses->Suid == ses_id) {
+				spin_lock(&ses->ses_lock);
 				ses_enc_key = enc ? ses->smb3encryptionkey :
 					ses->smb3decryptionkey;
 				memcpy(key, ses_enc_key, SMB3_ENC_DEC_KEY_SIZE);
+				spin_unlock(&ses->ses_lock);
 				spin_unlock(&cifs_tcp_ses_lock);
 				return 0;
 			}
@@ -5078,20 +5082,21 @@ static void smb2_decrypt_offload(struct work_struct *work)
 
 			mid->callback(mid);
 		} else {
-			spin_lock(&cifs_tcp_ses_lock);
-			spin_lock(&GlobalMid_Lock);
+			spin_lock(&dw->server->srv_lock);
 			if (dw->server->tcpStatus == CifsNeedReconnect) {
+				spin_lock(&dw->server->mid_lock);
 				mid->mid_state = MID_RETRY_NEEDED;
-				spin_unlock(&GlobalMid_Lock);
-				spin_unlock(&cifs_tcp_ses_lock);
+				spin_unlock(&dw->server->mid_lock);
+				spin_unlock(&dw->server->srv_lock);
 				mid->callback(mid);
 			} else {
+				spin_lock(&dw->server->mid_lock);
 				mid->mid_state = MID_REQUEST_SUBMITTED;
 				mid->mid_flags &= ~(MID_DELETED);
 				list_add_tail(&mid->qhead,
 					&dw->server->pending_mid_q);
-				spin_unlock(&GlobalMid_Lock);
-				spin_unlock(&cifs_tcp_ses_lock);
+				spin_unlock(&dw->server->mid_lock);
+				spin_unlock(&dw->server->srv_lock);
 			}
 		}
 		cifs_mid_q_entry_release(mid);

fs/cifs/smb2pdu.c

@@ -162,7 +162,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	if (smb2_command == SMB2_TREE_CONNECT || smb2_command == SMB2_IOCTL)
 		return 0;
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&tcon->tc_lock);
 	if (tcon->status == TID_EXITING) {
 		/*
 		 * only tree disconnect, open, and write,
@@ -172,13 +172,13 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		if ((smb2_command != SMB2_WRITE) &&
 		   (smb2_command != SMB2_CREATE) &&
 		   (smb2_command != SMB2_TREE_DISCONNECT)) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&tcon->tc_lock);
 			cifs_dbg(FYI, "can not send cmd %d while umounting\n",
 				 smb2_command);
 			return -ENODEV;
 		}
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&tcon->tc_lock);
 	if ((!tcon->ses) || (tcon->ses->ses_status == SES_EXITING) ||
 	    (!tcon->ses->server) || !server)
 		return -EIO;
@@ -217,12 +217,12 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		}
 
 		/* are we still trying to reconnect? */
-		spin_lock(&cifs_tcp_ses_lock);
+		spin_lock(&server->srv_lock);
 		if (server->tcpStatus != CifsNeedReconnect) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&server->srv_lock);
 			break;
 		}
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 
 		if (retries && --retries)
 			continue;
@@ -256,13 +256,13 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	 * and the server never sends an answer the socket will be closed
 	 * and tcpStatus set to reconnect.
 	 */
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		rc = -EHOSTDOWN;
 		goto out;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously
@@ -3911,15 +3911,15 @@ SMB2_echo(struct TCP_Server_Info *server)
 
 	cifs_dbg(FYI, "In echo request for conn_id %lld\n", server->conn_id);
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->ops->need_neg &&
 	    server->ops->need_neg(server)) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		/* No need to send echo on newly established connections */
 		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
 		return rc;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	rc = smb2_plain_req_init(SMB2_ECHO, NULL, server,
 				 (void **)&req, &total_len);

fs/cifs/smb2transport.c

@@ -640,13 +640,13 @@ smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 
 	if (!is_signed)
 		return 0;
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->ops->need_neg &&
 	    server->ops->need_neg(server)) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return 0;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 	if (!is_binding && !server->session_estab) {
 		strncpy(shdr->Signature, "BSRSPYL", 8);
 		return 0;
@@ -762,28 +762,30 @@ static int
 smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server,
 		   struct smb2_hdr *shdr, struct mid_q_entry **mid)
 {
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsExiting) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return -ENOENT;
 	}
 
 	if (server->tcpStatus == CifsNeedReconnect) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
 		return -EAGAIN;
 	}
 
 	if (server->tcpStatus == CifsNeedNegotiate &&
 	   shdr->Command != SMB2_NEGOTIATE) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return -EAGAIN;
 	}
+	spin_unlock(&server->srv_lock);
 
+	spin_lock(&ses->ses_lock);
 	if (ses->ses_status == SES_NEW) {
 		if ((shdr->Command != SMB2_SESSION_SETUP) &&
 		    (shdr->Command != SMB2_NEGOTIATE)) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&ses->ses_lock);
 			return -EAGAIN;
 		}
 		/* else ok - we are setting up session */
@@ -791,19 +793,19 @@ smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server,
 
 	if (ses->ses_status == SES_EXITING) {
 		if (shdr->Command != SMB2_LOGOFF) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&ses->ses_lock);
 			return -EAGAIN;
 		}
 		/* else ok - we are shutting down the session */
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&ses->ses_lock);
 
 	*mid = smb2_mid_entry_alloc(shdr, server);
 	if (*mid == NULL)
 		return -ENOMEM;
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	list_add_tail(&(*mid)->qhead, &server->pending_mid_q);
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 
 	return 0;
 }
@@ -869,13 +871,13 @@ smb2_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 			(struct smb2_hdr *)rqst->rq_iov[0].iov_base;
 	struct mid_q_entry *mid;
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsNeedNegotiate &&
 	   shdr->Command != SMB2_NEGOTIATE) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return ERR_PTR(-EAGAIN);
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	smb2_seq_num_into_buf(server, shdr);
 

fs/cifs/transport.c

@@ -154,9 +154,11 @@ static void _cifs_mid_q_entry_release(struct kref *refcount)
 
 void cifs_mid_q_entry_release(struct mid_q_entry *midEntry)
 {
-	spin_lock(&GlobalMid_Lock);
+	struct TCP_Server_Info *server = midEntry->server;
+
+	spin_lock(&server->mid_lock);
 	kref_put(&midEntry->refcount, _cifs_mid_q_entry_release);
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 }
 
 void DeleteMidQEntry(struct mid_q_entry *midEntry)
@@ -167,12 +169,12 @@ void DeleteMidQEntry(struct mid_q_entry *midEntry)
 void
 cifs_delete_mid(struct mid_q_entry *mid)
 {
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&mid->server->mid_lock);
 	if (!(mid->mid_flags & MID_DELETED)) {
 		list_del_init(&mid->qhead);
 		mid->mid_flags |= MID_DELETED;
 	}
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&mid->server->mid_lock);
 
 	DeleteMidQEntry(mid);
 }
@@ -577,12 +579,12 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 		} else {
 			spin_unlock(&server->req_lock);
 
-			spin_lock(&cifs_tcp_ses_lock);
+			spin_lock(&server->srv_lock);
 			if (server->tcpStatus == CifsExiting) {
-				spin_unlock(&cifs_tcp_ses_lock);
+				spin_unlock(&server->srv_lock);
 				return -ENOENT;
 			}
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&server->srv_lock);
 
 			/*
 			 * For normal commands, reserve the last MAX_COMPOUND
@@ -725,11 +727,11 @@ cifs_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
 			struct mid_q_entry **ppmidQ)
 {
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&ses->ses_lock);
 	if (ses->ses_status == SES_NEW) {
 		if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
 			(in_buf->Command != SMB_COM_NEGOTIATE)) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&ses->ses_lock);
 			return -EAGAIN;
 		}
 		/* else ok - we are setting up session */
@@ -738,19 +740,19 @@ static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
 	if (ses->ses_status == SES_EXITING) {
 		/* check if SMB session is bad because we are setting it up */
 		if (in_buf->Command != SMB_COM_LOGOFF_ANDX) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&ses->ses_lock);
 			return -EAGAIN;
 		}
 		/* else ok - we are shutting down session */
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&ses->ses_lock);
 
 	*ppmidQ = AllocMidQEntry(in_buf, ses->server);
 	if (*ppmidQ == NULL)
 		return -ENOMEM;
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&ses->server->mid_lock);
 	list_add_tail(&(*ppmidQ)->qhead, &ses->server->pending_mid_q);
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&ses->server->mid_lock);
 	return 0;
 }
 
@@ -849,9 +851,9 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
 	mid->mid_state = MID_REQUEST_SUBMITTED;
 
 	/* put it on the pending_mid_q */
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	list_add_tail(&mid->qhead, &server->pending_mid_q);
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 
 	/*
 	 * Need to store the time in mid before calling I/O. For call_async,
@@ -912,10 +914,10 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
 	cifs_dbg(FYI, "%s: cmd=%d mid=%llu state=%d\n",
 		 __func__, le16_to_cpu(mid->command), mid->mid, mid->mid_state);
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&server->mid_lock);
 	switch (mid->mid_state) {
 	case MID_RESPONSE_RECEIVED:
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&server->mid_lock);
 		return rc;
 	case MID_RETRY_NEEDED:
 		rc = -EAGAIN;
@@ -935,7 +937,7 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
 			 __func__, mid->mid, mid->mid_state);
 		rc = -EIO;
 	}
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&server->mid_lock);
 
 	DeleteMidQEntry(mid);
 	return rc;
@@ -1078,12 +1080,12 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 		return -EIO;
 	}
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsExiting) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return -ENOENT;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	/*
 	 * Wait for all the requests to become available.
@@ -1186,17 +1188,17 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	/*
 	 * Compounding is never used during session establish.
 	 */
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&ses->ses_lock);
 	if ((ses->ses_status == SES_NEW) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&ses->ses_lock);
 
 		cifs_server_lock(server);
 		smb311_update_preauth_hash(ses, server, rqst[0].rq_iov, rqst[0].rq_nvec);
 		cifs_server_unlock(server);
 
-		spin_lock(&cifs_tcp_ses_lock);
+		spin_lock(&ses->ses_lock);
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&ses->ses_lock);
 
 	for (i = 0; i < num_rqst; i++) {
 		rc = wait_for_response(server, midQ[i]);
@@ -1208,14 +1210,14 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 			cifs_server_dbg(FYI, "Cancelling wait for mid %llu cmd: %d\n",
 				 midQ[i]->mid, le16_to_cpu(midQ[i]->command));
 			send_cancel(server, &rqst[i], midQ[i]);
-			spin_lock(&GlobalMid_Lock);
+			spin_lock(&server->mid_lock);
 			midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
 			if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) {
 				midQ[i]->callback = cifs_cancelled_callback;
 				cancelled_mid[i] = true;
 				credits[i].value = 0;
 			}
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&server->mid_lock);
 		}
 	}
 
@@ -1259,19 +1261,19 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	/*
 	 * Compounding is never used during session establish.
 	 */
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&ses->ses_lock);
 	if ((ses->ses_status == SES_NEW) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
 		struct kvec iov = {
 			.iov_base = resp_iov[0].iov_base,
 			.iov_len = resp_iov[0].iov_len
 		};
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&ses->ses_lock);
 		cifs_server_lock(server);
 		smb311_update_preauth_hash(ses, server, &iov, 1);
 		cifs_server_unlock(server);
-		spin_lock(&cifs_tcp_ses_lock);
+		spin_lock(&ses->ses_lock);
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&ses->ses_lock);
 
 out:
 	/*
@@ -1360,12 +1362,12 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
 		return -EIO;
 	}
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsExiting) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return -ENOENT;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	/* Ensure that we do not send more than 50 overlapping requests
 	   to the same server. We may make this configurable later or
@@ -1419,15 +1421,15 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
 	rc = wait_for_response(server, midQ);
 	if (rc != 0) {
 		send_cancel(server, &rqst, midQ);
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&server->mid_lock);
 		if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
 			/* no longer considered to be "in-flight" */
 			midQ->callback = DeleteMidQEntry;
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&server->mid_lock);
 			add_credits(server, &credits, 0);
 			return rc;
 		}
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&server->mid_lock);
 	}
 
 	rc = cifs_sync_mid_result(midQ, server);
@@ -1505,12 +1507,12 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		return -EIO;
 	}
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsExiting) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		return -ENOENT;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	/* Ensure that we do not send more than 50 overlapping requests
 	   to the same server. We may make this configurable later or
@@ -1568,12 +1570,12 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		 (server->tcpStatus != CifsNew)));
 
 	/* Were we interrupted by a signal ? */
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if ((rc == -ERESTARTSYS) &&
 		(midQ->mid_state == MID_REQUEST_SUBMITTED) &&
 		((server->tcpStatus == CifsGood) ||
 		 (server->tcpStatus == CifsNew))) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 
 		if (in_buf->Command == SMB_COM_TRANSACTION2) {
 			/* POSIX lock. We send a NT_CANCEL SMB to cause the
@@ -1600,21 +1602,21 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		rc = wait_for_response(server, midQ);
 		if (rc) {
 			send_cancel(server, &rqst, midQ);
-			spin_lock(&GlobalMid_Lock);
+			spin_lock(&server->mid_lock);
 			if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
 				/* no longer considered to be "in-flight" */
 				midQ->callback = DeleteMidQEntry;
-				spin_unlock(&GlobalMid_Lock);
+				spin_unlock(&server->mid_lock);
 				return rc;
 			}
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&server->mid_lock);
 		}
 
 		/* We got the response - restart system call. */
 		rstart = 1;
-		spin_lock(&cifs_tcp_ses_lock);
+		spin_lock(&server->srv_lock);
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	rc = cifs_sync_mid_result(midQ, server);
 	if (rc != 0)