Add resilienthandles mount parm

Since many servers (Windows clients, and non-clustered servers) do not
support persistent handles but do support resilient handles, allow
the user to specify a mount option "resilienthandles" in order
to get more reliable connections and less chance of data loss
(at least when SMB2.1 or later).  Default resilient handle
timeout (120 seconds to recent Windows server) is used.

Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <steve.french@primarydata.com>

fs/cifs/cifsfs.c

@@ -456,6 +456,8 @@ cifs_show_options(struct seq_file *s, struct dentry *root)
 		seq_puts(s, ",hard");
 	if (tcon->use_persistent)
 		seq_puts(s, ",persistenthandles");
+	else if (tcon->use_resilient)
+		seq_puts(s, ",resilienthandles");
 	if (tcon->unix_ext)
 		seq_puts(s, ",unix");
 	else

fs/cifs/cifsglob.h

@@ -496,6 +496,7 @@ struct smb_vol {
 	bool nosharesock:1;
 	bool persistent:1;
 	bool nopersistent:1;
+	bool resilient:1; /* noresilient not required since not fored for CA */
 	unsigned int rsize;
 	unsigned int wsize;
 	bool sockopt_tcp_nodelay:1;
@@ -897,6 +898,7 @@ struct cifs_tcon {
 	bool broken_posix_open; /* e.g. Samba server versions < 3.3.2, 3.2.9 */
 	bool broken_sparse_sup; /* if server or share does not support sparse */
 	bool need_reconnect:1; /* connection reset, tid now invalid */
+	bool use_resilient:1; /* use resilient instead of durable handles */
 	bool use_persistent:1; /* use persistent instead of durable handles */
 #ifdef CONFIG_CIFS_SMB2
 	bool print:1;		/* set if connection to printer share */

fs/cifs/connect.c

@@ -88,6 +88,7 @@ enum {
 	Opt_fsc, Opt_mfsymlinks,
 	Opt_multiuser, Opt_sloppy, Opt_nosharesock,
 	Opt_persistent, Opt_nopersistent,
+	Opt_resilient, Opt_noresilient,
 
 	/* Mount options which take numeric value */
 	Opt_backupuid, Opt_backupgid, Opt_uid,
@@ -172,6 +173,8 @@ static const match_table_t cifs_mount_option_tokens = {
 	{ Opt_nosharesock, "nosharesock" },
 	{ Opt_persistent, "persistenthandles"},
 	{ Opt_nopersistent, "nopersistenthandles"},
+	{ Opt_resilient, "resilienthandles"},
+	{ Opt_noresilient, "noresilienthandles"},
 
 	{ Opt_backupuid, "backupuid=%s" },
 	{ Opt_backupgid, "backupgid=%s" },
@@ -1510,12 +1513,23 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 			break;
 		case Opt_persistent:
 			vol->persistent = true;
-			if (vol->nopersistent) {
+			if ((vol->nopersistent) || (vol->resilient)) {
 				cifs_dbg(VFS,
 				  "persistenthandles mount options conflict\n");
 				goto cifs_parse_mount_err;
 			}
 			break;
+		case Opt_resilient:
+			vol->resilient = true;
+			if (vol->persistent) {
+				cifs_dbg(VFS,
+				  "persistenthandles mount options conflict\n");
+				goto cifs_parse_mount_err;
+			}
+			break;
+		case Opt_noresilient:
+			vol->resilient = false; /* already the default */
+			break;
 
 		/* Numeric Values */
 		case Opt_backupuid:
@@ -2681,6 +2695,7 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
 			     "SMB3 or later required for persistent handles\n");
 			rc = -EOPNOTSUPP;
 			goto out_fail;
+#ifdef CONFIG_CIFS_SMB2
 		} else if (ses->server->capabilities &
 			   SMB2_GLOBAL_CAP_PERSISTENT_HANDLES)
 			tcon->use_persistent = true;
@@ -2689,12 +2704,23 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
 				"Persistent handles not supported on share\n");
 			rc = -EOPNOTSUPP;
 			goto out_fail;
+#endif /* CONFIG_CIFS_SMB2 */
 		}
+#ifdef CONFIG_CIFS_SMB2
 	} else if ((tcon->capabilities & SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY)
 	     && (ses->server->capabilities & SMB2_GLOBAL_CAP_PERSISTENT_HANDLES)
 	     && (volume_info->nopersistent == false)) {
 		cifs_dbg(FYI, "enabling persistent handles\n");
 		tcon->use_persistent = true;
+#endif /* CONFIG_CIFS_SMB2 */
+	} else if (volume_info->resilient) {
+		if (ses->server->vals->protocol_id == 0) {
+			cifs_dbg(VFS,
+			     "SMB2.1 or later required for resilient handles\n");
+			rc = -EOPNOTSUPP;
+			goto out_fail;
+		}
+		tcon->use_resilient = true;
 	}
 
 	/*
@@ -3545,12 +3571,15 @@ try_mount_again:
 		goto mount_fail_check;
 	}
 
+#ifdef CONFIG_CIFS_SMB2
 	if ((volume_info->persistent == true) && ((ses->server->capabilities &
 		SMB2_GLOBAL_CAP_PERSISTENT_HANDLES) == 0)) {
 		cifs_dbg(VFS, "persistent handles not supported by server\n");
 		rc = -EOPNOTSUPP;
 		goto mount_fail_check;
 	}
+#endif /* CONFIG_CIFS_SMB2*/
+
 	/* search for existing tcon to this server share */
 	tcon = cifs_get_tcon(ses, volume_info);
 	if (IS_ERR(tcon)) {

fs/cifs/smb2file.c

@@ -43,6 +43,7 @@ smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms,
 	struct smb2_file_all_info *smb2_data = NULL;
 	__u8 smb2_oplock[17];
 	struct cifs_fid *fid = oparms->fid;
+	struct network_resiliency_req nr_ioctl_req;
 
 	smb2_path = cifs_convert_path_to_utf16(oparms->path, oparms->cifs_sb);
 	if (smb2_path == NULL) {
@@ -67,6 +68,24 @@ smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms,
 	if (rc)
 		goto out;
 
+
+	 if (oparms->tcon->use_resilient) {
+		nr_ioctl_req.Timeout = 0; /* use server default (120 seconds) */
+		nr_ioctl_req.Reserved = 0;
+		rc = SMB2_ioctl(xid, oparms->tcon, fid->persistent_fid,
+			fid->volatile_fid, FSCTL_LMR_REQUEST_RESILIENCY, true,
+			(char *)&nr_ioctl_req, sizeof(nr_ioctl_req),
+			NULL, NULL /* no return info */);
+		if (rc == -EOPNOTSUPP) {
+			cifs_dbg(VFS,
+			     "resiliency not supported by server, disabling\n");
+			oparms->tcon->use_resilient = false;
+		} else if (rc)
+			cifs_dbg(FYI, "error %d setting resiliency\n", rc);
+
+		rc = 0;
+	}
+
 	if (buf) {
 		/* open response does not have IndexNumber field - get it */
 		rc = SMB2_get_srv_num(xid, oparms->tcon, fid->persistent_fid,