smb: client: negotiate compression algorithms

Change "compress=" mount option to a boolean flag, that, if set,
will enable negotiating compression algorithms with the server.

Do not de/compress anything for now.
Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/cifs_debug.c

@@ -278,6 +278,24 @@ static int cifs_debug_files_proc_show(struct seq_file *m, void *v)
 	return 0;
 }
 
+static __always_inline const char *compression_alg_str(__le16 alg)
+{
+	switch (alg) {
+	case SMB3_COMPRESS_NONE:
+		return "NONE";
+	case SMB3_COMPRESS_LZNT1:
+		return "LZNT1";
+	case SMB3_COMPRESS_LZ77:
+		return "LZ77";
+	case SMB3_COMPRESS_LZ77_HUFF:
+		return "LZ77-Huffman";
+	case SMB3_COMPRESS_PATTERN:
+		return "Pattern_V1";
+	default:
+		return "invalid";
+	}
+}
+
 static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 {
 	struct mid_q_entry *mid_entry;
@@ -423,12 +441,6 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 			server->echo_credits,
 			server->oplock_credits,
 			server->dialect);
-		if (server->compress_algorithm == SMB3_COMPRESS_LZNT1)
-			seq_printf(m, " COMPRESS_LZNT1");
-		else if (server->compress_algorithm == SMB3_COMPRESS_LZ77)
-			seq_printf(m, " COMPRESS_LZ77");
-		else if (server->compress_algorithm == SMB3_COMPRESS_LZ77_HUFF)
-			seq_printf(m, " COMPRESS_LZ77_HUFF");
 		if (server->sign)
 			seq_printf(m, " signed");
 		if (server->posix_ext_supported)
@@ -460,6 +472,14 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 				   server->leaf_fullpath);
 		}
 
+		seq_puts(m, "\nCompression: ");
+		if (!server->compression.requested)
+			seq_puts(m, "disabled on mount");
+		else if (server->compression.enabled)
+			seq_printf(m, "enabled (%s)", compression_alg_str(server->compression.alg));
+		else
+			seq_puts(m, "disabled (not supported by this server)");
+
 		seq_printf(m, "\n\n\tSessions: ");
 		i = 0;
 		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {

fs/smb/client/cifsglob.h

@@ -769,7 +769,11 @@ struct TCP_Server_Info {
 	unsigned int	max_write;
 	unsigned int	min_offload;
 	unsigned int	retrans;
-	__le16	compress_algorithm;
+	struct {
+		bool requested; /* "compress" mount option set*/
+		bool enabled; /* actually negotiated with server */
+		__le16 alg; /* preferred alg negotiated with server */
+	} compression;
 	__u16	signing_algorithm;
 	__le16	cipher_type;
 	 /* save initital negprot hash */

fs/smb/client/connect.c

@@ -1736,7 +1736,7 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx,
 	tcp_ses->channel_sequence_num = 0; /* only tracked for primary channel */
 	tcp_ses->reconnect_instance = 1;
 	tcp_ses->lstrp = jiffies;
-	tcp_ses->compress_algorithm = cpu_to_le16(ctx->compression);
+	tcp_ses->compression.requested = ctx->compress;
 	spin_lock_init(&tcp_ses->req_lock);
 	spin_lock_init(&tcp_ses->srv_lock);
 	spin_lock_init(&tcp_ses->mid_lock);

fs/smb/client/fs_context.c

@@ -963,7 +963,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
 
 	switch (opt) {
 	case Opt_compress:
-		ctx->compression = UNKNOWN_TYPE;
+		ctx->compress = true;
 		cifs_dbg(VFS,
 			"SMB3 compression support is experimental\n");
 		break;

fs/smb/client/fs_context.h

@@ -273,7 +273,7 @@ struct smb3_fs_context {
 	unsigned int max_credits; /* smb3 max_credits 10 < credits < 60000 */
 	unsigned int max_channels;
 	unsigned int max_cached_dirs;
-	__u16 compression; /* compression algorithm 0xFFFF default 0=disabled */
+	bool compress; /* enable SMB2 messages (READ/WRITE) de/compression */
 	bool rootfs:1; /* if it's a SMB root file system */
 	bool witness:1; /* use witness protocol */
 	char *leaf_fullpath;

fs/smb/client/smb2pdu.c

@@ -731,7 +731,7 @@ assemble_neg_contexts(struct smb2_negotiate_req *req,
 	pneg_ctxt += sizeof(struct smb2_posix_neg_context);
 	neg_context_count++;
 
-	if (server->compress_algorithm) {
+	if (server->compression.requested) {
 		build_compression_ctxt((struct smb2_compression_capabilities_context *)
 				pneg_ctxt);
 		ctxt_len = ALIGN(sizeof(struct smb2_compression_capabilities_context), 8);
@@ -779,6 +779,9 @@ static void decode_compress_ctx(struct TCP_Server_Info *server,
 			 struct smb2_compression_capabilities_context *ctxt)
 {
 	unsigned int len = le16_to_cpu(ctxt->DataLength);
+	__le16 alg;
+
+	server->compression.enabled = false;
 
 	/*
 	 * Caller checked that DataLength remains within SMB boundary. We still
@@ -789,15 +792,22 @@ static void decode_compress_ctx(struct TCP_Server_Info *server,
 		pr_warn_once("server sent bad compression cntxt\n");
 		return;
 	}
+
 	if (le16_to_cpu(ctxt->CompressionAlgorithmCount) != 1) {
-		pr_warn_once("Invalid SMB3 compress algorithm count\n");
+		pr_warn_once("invalid SMB3 compress algorithm count\n");
 		return;
 	}
-	if (le16_to_cpu(ctxt->CompressionAlgorithms[0]) > 3) {
-		pr_warn_once("unknown compression algorithm\n");
+
+	alg = ctxt->CompressionAlgorithms[0];
+
+	/* 'NONE' (0) compressor type is never negotiated */
+	if (alg == 0 || le16_to_cpu(alg) > 3) {
+		pr_warn_once("invalid compression algorithm '%u'\n", alg);
 		return;
 	}
-	server->compress_algorithm = ctxt->CompressionAlgorithms[0];
+
+	server->compression.alg = alg;
+	server->compression.enabled = true;
 }
 
 static int decode_encrypt_ctx(struct TCP_Server_Info *server,