cifs: fix charset issue in reconnection

We need to specify charset, like "iocharset=utf-8", in mount options for
Chinese path if the nls_default don't support it, such as iso8859-1, the
default value for CONFIG_NLS_DEFAULT.

But now in reconnection the nls_default is used, instead of the one we
specified and used in mount, and this can lead to mount failure.

Signed-off-by: Winston Wen <wentao@uniontech.com>
Reviewed-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/cifsglob.h

@@ -1062,6 +1062,7 @@ struct cifs_ses {
 	unsigned long chans_need_reconnect;
 	/* ========= end: protected by chan_lock ======== */
 	struct cifs_ses *dfs_root_ses;
+	struct nls_table *local_nls;
 };
 
 static inline bool

fs/smb/client/cifssmb.c

@@ -129,7 +129,7 @@ again:
 	}
 	spin_unlock(&server->srv_lock);
 
-	nls_codepage = load_nls_default();
+	nls_codepage = ses->local_nls;
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously
@@ -200,7 +200,6 @@ out:
 		rc = -EAGAIN;
 	}
 
-	unload_nls(nls_codepage);
 	return rc;
 }
 

fs/smb/client/connect.c

@@ -1842,6 +1842,10 @@ static int match_session(struct cifs_ses *ses, struct smb3_fs_context *ctx)
 			    CIFS_MAX_PASSWORD_LEN))
 			return 0;
 	}
+
+	if (strcmp(ctx->local_nls->charset, ses->local_nls->charset))
+		return 0;
+
 	return 1;
 }
 
@@ -2286,6 +2290,7 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
 
 	ses->sectype = ctx->sectype;
 	ses->sign = ctx->sign;
+	ses->local_nls = load_nls(ctx->local_nls->charset);
 
 	/* add server as first channel */
 	spin_lock(&ses->chan_lock);

fs/smb/client/misc.c

@@ -95,6 +95,7 @@ sesInfoFree(struct cifs_ses *buf_to_free)
 		return;
 	}
 
+	unload_nls(buf_to_free->local_nls);
 	atomic_dec(&sesInfoAllocCount);
 	kfree(buf_to_free->serverOS);
 	kfree(buf_to_free->serverDomain);

fs/smb/client/smb2pdu.c

@@ -242,7 +242,7 @@ again:
 	}
 	spin_unlock(&server->srv_lock);
 
-	nls_codepage = load_nls_default();
+	nls_codepage = ses->local_nls;
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously
@@ -324,7 +324,6 @@ out:
 		rc = -EAGAIN;
 	}
 failed:
-	unload_nls(nls_codepage);
 	return rc;
 }