four small SMB3 fixes, all for stable

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Merge tag '5.2-rc5-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs fixes from Steve French:
 "Four small SMB3 fixes, all for stable"

* tag '5.2-rc5-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: fix GlobalMid_Lock bug in cifs_reconnect
  SMB3: retry on STATUS_INSUFFICIENT_RESOURCES instead of failing write
  cifs: add spinlock for the openFileList to cifsInodeInfo
  cifs: fix panic in smb2_reconnect

fs/cifs/cifsfs.c

@@ -303,6 +303,7 @@ cifs_alloc_inode(struct super_block *sb)
 	cifs_inode->uniqueid = 0;
 	cifs_inode->createtime = 0;
 	cifs_inode->epoch = 0;
+	spin_lock_init(&cifs_inode->open_file_lock);
 	generate_random_uuid(cifs_inode->lease_key);
 
 	/*

fs/cifs/cifsglob.h

@@ -1377,6 +1377,7 @@ struct cifsInodeInfo {
 	struct rw_semaphore lock_sem;	/* protect the fields above */
 	/* BB add in lists for dirty pages i.e. write caching info for oplock */
 	struct list_head openFileList;
+	spinlock_t	open_file_lock;	/* protects openFileList */
 	__u32 cifsAttrs; /* e.g. DOS archive bit, sparse, compressed, system */
 	unsigned int oplock;		/* oplock/lease level we have */
 	unsigned int epoch;		/* used to track lease state changes */
@@ -1780,10 +1781,14 @@ require use of the stronger protocol */
  *  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
  *
+ *  Note that the cifs_tcon.open_file_lock should be taken before
+ *  not after the cifsInodeInfo.open_file_lock
+ *
  *  Semaphores
  *  ----------
  *  sesSem     operations on smb session

fs/cifs/connect.c

@@ -476,6 +476,7 @@ cifs_reconnect(struct TCP_Server_Info *server)
 	spin_lock(&GlobalMid_Lock);
 	server->nr_targets = 1;
 #ifdef CONFIG_CIFS_DFS_UPCALL
+	spin_unlock(&GlobalMid_Lock);
 	cifs_sb = find_super_by_tcp(server);
 	if (IS_ERR(cifs_sb)) {
 		rc = PTR_ERR(cifs_sb);
@@ -493,6 +494,7 @@ cifs_reconnect(struct TCP_Server_Info *server)
 	}
 	cifs_dbg(FYI, "%s: will retry %d target(s)\n", __func__,
 		 server->nr_targets);
+	spin_lock(&GlobalMid_Lock);
 #endif
 	if (server->tcpStatus == CifsExiting) {
 		/* the demux thread will exit normally

fs/cifs/file.c

@@ -338,10 +338,12 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
 	atomic_inc(&tcon->num_local_opens);
 
 	/* if readable file instance put first in list*/
+	spin_lock(&cinode->open_file_lock);
 	if (file->f_mode & FMODE_READ)
 		list_add(&cfile->flist, &cinode->openFileList);
 	else
 		list_add_tail(&cfile->flist, &cinode->openFileList);
+	spin_unlock(&cinode->open_file_lock);
 	spin_unlock(&tcon->open_file_lock);
 
 	if (fid->purge_cache)
@@ -413,7 +415,9 @@ void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler)
 	cifs_add_pending_open_locked(&fid, cifs_file->tlink, &open);
 
 	/* remove it from the lists */
+	spin_lock(&cifsi->open_file_lock);
 	list_del(&cifs_file->flist);
+	spin_unlock(&cifsi->open_file_lock);
 	list_del(&cifs_file->tlist);
 	atomic_dec(&tcon->num_local_opens);
 
@@ -1950,9 +1954,9 @@ refind_writable:
 			return 0;
 		}
 
-		spin_lock(&tcon->open_file_lock);
+		spin_lock(&cifs_inode->open_file_lock);
 		list_move_tail(&inv_file->flist, &cifs_inode->openFileList);
-		spin_unlock(&tcon->open_file_lock);
+		spin_unlock(&cifs_inode->open_file_lock);
 		cifsFileInfo_put(inv_file);
 		++refind;
 		inv_file = NULL;

fs/cifs/smb2maperror.c

@@ -457,7 +457,7 @@ static const struct status_to_posix_error smb2_error_map_table[] = {
 	{STATUS_FILE_INVALID, -EIO, "STATUS_FILE_INVALID"},
 	{STATUS_ALLOTTED_SPACE_EXCEEDED, -EIO,
 	"STATUS_ALLOTTED_SPACE_EXCEEDED"},
-	{STATUS_INSUFFICIENT_RESOURCES, -EREMOTEIO,
+	{STATUS_INSUFFICIENT_RESOURCES, -EAGAIN,
 				"STATUS_INSUFFICIENT_RESOURCES"},
 	{STATUS_DFS_EXIT_PATH_FOUND, -EIO, "STATUS_DFS_EXIT_PATH_FOUND"},
 	{STATUS_DEVICE_DATA_ERROR, -EIO, "STATUS_DEVICE_DATA_ERROR"},

fs/cifs/smb2pdu.c

@@ -3114,9 +3114,14 @@ void smb2_reconnect_server(struct work_struct *work)
 				tcon_exist = true;
 			}
 		}
+		/*
+		 * IPC has the same lifetime as its session and uses its
+		 * refcount.
+		 */
 		if (ses->tcon_ipc && ses->tcon_ipc->need_reconnect) {
 			list_add_tail(&ses->tcon_ipc->rlist, &tmp_list);
 			tcon_exist = true;
+			ses->ses_count++;
 		}
 	}
 	/*
@@ -3135,7 +3140,10 @@ void smb2_reconnect_server(struct work_struct *work)
 		else
 			resched = true;
 		list_del_init(&tcon->rlist);
-		cifs_put_tcon(tcon);
+		if (tcon->ipc)
+			cifs_put_smb_ses(tcon->ses);
+		else
+			cifs_put_tcon(tcon);
 	}
 
 	cifs_dbg(FYI, "Reconnecting tcons finished\n");