smb3: allow disabling requesting leases

In some cases to work around server bugs or performance
problems it can be helpful to be able to disable requesting
SMB2.1/SMB3 leases on a particular mount (not to all servers
and all shares we are mounted to). Add new mount parm
"nolease" which turns off requesting leases on directory
or file opens.  Currently the only way to disable leases is
globally through a module load parameter. This is more
granular.
Suggested-by: NPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: NPavel Shilovsky <pshilov@microsoft.com>
CC: Stable <stable@vger.kernel.org>

fs/cifs/cifsfs.c

@@ -438,6 +438,8 @@ cifs_show_options(struct seq_file *s, struct dentry *root)
 	cifs_show_security(s, tcon->ses);
 	cifs_show_cache_flavor(s, cifs_sb);
 
+	if (tcon->no_lease)
+		seq_puts(s, ",nolease");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER)
 		seq_puts(s, ",multiuser");
 	else if (tcon->ses->user_name)

fs/cifs/cifsglob.h

@@ -579,6 +579,7 @@ struct smb_vol {
 	bool noblocksnd:1;
 	bool noautotune:1;
 	bool nostrictsync:1; /* do not force expensive SMBflush on every sync */
+	bool no_lease:1;     /* disable requesting leases */
 	bool fsc:1;	/* enable fscache */
 	bool mfsymlinks:1; /* use Minshall+French Symlinks */
 	bool multiuser:1;
@@ -1090,6 +1091,7 @@ struct cifs_tcon {
 	bool need_reopen_files:1; /* need to reopen tcon file handles */
 	bool use_resilient:1; /* use resilient instead of durable handles */
 	bool use_persistent:1; /* use persistent instead of durable handles */
+	bool no_lease:1;    /* Do not request leases on files or directories */
 	__le32 capabilities;
 	__u32 share_flags;
 	__u32 maximal_access;

fs/cifs/connect.c

@@ -74,7 +74,7 @@ enum {
 	Opt_user_xattr, Opt_nouser_xattr,
 	Opt_forceuid, Opt_noforceuid,
 	Opt_forcegid, Opt_noforcegid,
-	Opt_noblocksend, Opt_noautotune,
+	Opt_noblocksend, Opt_noautotune, Opt_nolease,
 	Opt_hard, Opt_soft, Opt_perm, Opt_noperm,
 	Opt_mapposix, Opt_nomapposix,
 	Opt_mapchars, Opt_nomapchars, Opt_sfu,
@@ -135,6 +135,7 @@ static const match_table_t cifs_mount_option_tokens = {
 	{ Opt_noforcegid, "noforcegid" },
 	{ Opt_noblocksend, "noblocksend" },
 	{ Opt_noautotune, "noautotune" },
+	{ Opt_nolease, "nolease" },
 	{ Opt_hard, "hard" },
 	{ Opt_soft, "soft" },
 	{ Opt_perm, "perm" },
@@ -1738,6 +1739,9 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 		case Opt_noautotune:
 			vol->noautotune = 1;
 			break;
+		case Opt_nolease:
+			vol->no_lease = 1;
+			break;
 		case Opt_hard:
 			vol->retry = 1;
 			break;
@@ -3294,6 +3298,8 @@ static int match_tcon(struct cifs_tcon *tcon, struct smb_vol *volume_info)
 		return 0;
 	if (tcon->handle_timeout != volume_info->handle_timeout)
 		return 0;
+	if (tcon->no_lease != volume_info->no_lease)
+		return 0;
 	return 1;
 }
 
@@ -3516,6 +3522,7 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
 	tcon->nocase = volume_info->nocase;
 	tcon->nohandlecache = volume_info->nohandlecache;
 	tcon->local_lease = volume_info->local_lease;
+	tcon->no_lease = volume_info->no_lease;
 	INIT_LIST_HEAD(&tcon->pending_opens);
 
 	spin_lock(&cifs_tcp_ses_lock);

fs/cifs/smb2pdu.c

@@ -2459,7 +2459,7 @@ SMB2_open_init(struct cifs_tcon *tcon, struct smb_rqst *rqst, __u8 *oplock,
 	iov[1].iov_len = uni_path_len;
 	iov[1].iov_base = path;
 
-	if (!server->oplocks)
+	if ((!server->oplocks) || (tcon->no_lease))
 		*oplock = SMB2_OPLOCK_LEVEL_NONE;
 
 	if (!(server->capabilities & SMB2_GLOBAL_CAP_LEASING) ||