smb3: do not send compression info by default

Since in theory a server could respond with compressed read
responses even if not requested on read request (assuming that
a compression negcontext is sent in negotiate protocol) - do
not send compression information during negotiate protocol
unless the user asks for compression explicitly (compression
is experimental), and add a mount warning that compression
is experimental.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index a4af850..fe610e7 100644 (file)
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -601,6 +601,7 @@ struct smb_vol {
        __u64 snapshot_time; /* needed for timewarp tokens */
        __u32 handle_timeout; /* persistent and durable handle timeout in ms */
        unsigned int max_credits; /* smb3 max_credits 10 < credits < 60000 */
+       __u16 compression; /* compression algorithm 0xFFFF default 0=disabled */
 };
 
 /**

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 07c9cd7..8ad8bbe 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -97,6 +97,7 @@ enum {
        Opt_persistent, Opt_nopersistent,
        Opt_resilient, Opt_noresilient,
        Opt_domainauto, Opt_rdma, Opt_modesid,
+       Opt_compress,
 
        /* Mount options which take numeric value */
        Opt_backupuid, Opt_backupgid, Opt_uid,
@@ -213,6 +214,7 @@ static const match_table_t cifs_mount_option_tokens = {
        { Opt_echo_interval, "echo_interval=%s" },
        { Opt_max_credits, "max_credits=%s" },
        { Opt_snapshot, "snapshot=%s" },
+       { Opt_compress, "compress=%s" },
 
        { Opt_blank_user, "user=" },
        { Opt_blank_user, "username=" },
@@ -1915,6 +1917,11 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
                case Opt_rdma:
                        vol->rdma = true;
                        break;
+               case Opt_compress:
+                       vol->compression = UNKNOWN_TYPE;
+                       cifs_dbg(VFS,
+                               "SMB3 compression support is experimental\n");
+                       break;
 
                /* Numeric Values */
                case Opt_backupuid:
@@ -2691,6 +2698,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
        tcp_ses->sequence_number = 0;
        tcp_ses->reconnect_instance = 1;
        tcp_ses->lstrp = jiffies;
+       tcp_ses->compress_algorithm = cpu_to_le16(volume_info->compression);
        spin_lock_init(&tcp_ses->req_lock);
        INIT_LIST_HEAD(&tcp_ses->tcp_ses_list);
        INIT_LIST_HEAD(&tcp_ses->smb_ses_list);

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index ab3300a..8e28940 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -521,7 +521,7 @@ build_posix_ctxt(struct smb2_posix_neg_context *pneg_ctxt)
 
 static void
 assemble_neg_contexts(struct smb2_negotiate_req *req,
-                     unsigned int *total_len)
+                     struct TCP_Server_Info *server, unsigned int *total_len)
 {
        char *pneg_ctxt = (char *)req;
        unsigned int ctxt_len;
@@ -551,17 +551,19 @@ assemble_neg_contexts(struct smb2_negotiate_req *req,
        *total_len += ctxt_len;
        pneg_ctxt += ctxt_len;
 
-       build_compression_ctxt((struct smb2_compression_capabilities_context *)
+       if (server->compress_algorithm) {
+               build_compression_ctxt((struct smb2_compression_capabilities_context *)
                                pneg_ctxt);
-       ctxt_len = DIV_ROUND_UP(
-               sizeof(struct smb2_compression_capabilities_context), 8) * 8;
-       *total_len += ctxt_len;
-       pneg_ctxt += ctxt_len;
-
+               ctxt_len = DIV_ROUND_UP(
+                       sizeof(struct smb2_compression_capabilities_context),
+                               8) * 8;
+               *total_len += ctxt_len;
+               pneg_ctxt += ctxt_len;
+               req->NegotiateContextCount = cpu_to_le16(4);
+       } else
+               req->NegotiateContextCount = cpu_to_le16(3);
        build_posix_ctxt((struct smb2_posix_neg_context *)pneg_ctxt);
        *total_len += sizeof(struct smb2_posix_neg_context);
-
-       req->NegotiateContextCount = cpu_to_le16(4);
 }
 
 static void decode_preauth_context(struct smb2_preauth_neg_context *ctxt)
@@ -829,7 +831,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
                if ((ses->server->vals->protocol_id == SMB311_PROT_ID) ||
                    (strcmp(ses->server->vals->version_string,
                     SMBDEFAULT_VERSION_STRING) == 0))
-                       assemble_neg_contexts(req, &total_len);
+                       assemble_neg_contexts(req, server, &total_len);
        }
        iov[0].iov_base = (char *)req;
        iov[0].iov_len = total_len;