NFSD: Clear TIME_DELEG in the suppattr_exclcreat bitmap

>From RFC 8881:

5.8.1.14. Attribute 75: suppattr_exclcreat

> The bit vector that would set all REQUIRED and RECOMMENDED
> attributes that are supported by the EXCLUSIVE4_1 method of file
> creation via the OPEN operation. The scope of this attribute
> applies to all objects with a matching fsid.

There's nothing in RFC 8881 that states that suppattr_exclcreat is
or is not allowed to contain bits for attributes that are clear in
the reported supported_attrs bitmask. But it doesn't make sense for
an NFS server to indicate that it /doesn't/ implement an attribute,
but then also indicate that clients /are/ allowed to set that
attribute using OPEN(create) with EXCLUSIVE4_1.

The FATTR4_WORD2_TIME_DELEG attributes are also not to be allowed
for OPEN(create) with EXCLUSIVE4_1. It doesn't make sense to set
a delegated timestamp on a new file.

Fixes: 7e13f4f8d27d ("nfsd: handle delegated timestamps in SETATTR")
Cc: [e-mail]
Reviewed-by: Jeff Layton <[e-mail]>
Signed-off-by: Chuck Lever <[e-mail]>

fs/nfsd/nfsd.h

···
 #define NFSD_SUPPATTR_EXCLCREAT_WORD1 \
 	(NFSD_WRITEABLE_ATTRS_WORD1 & \
 	 ~(FATTR4_WORD1_TIME_ACCESS_SET | FATTR4_WORD1_TIME_MODIFY_SET))
+/*
+ * The FATTR4_WORD2_TIME_DELEG attributes are not to be allowed for
+ * OPEN(create) with EXCLUSIVE4_1. It doesn't make sense to set a
+ * delegated timestamp on a new file.
+ */
 #define NFSD_SUPPATTR_EXCLCREAT_WORD2 \
-	NFSD_WRITEABLE_ATTRS_WORD2
+	(NFSD_WRITEABLE_ATTRS_WORD2 & \
+	~(FATTR4_WORD2_TIME_DELEG_ACCESS | FATTR4_WORD2_TIME_DELEG_MODIFY))
 
 extern int nfsd4_is_junction(struct dentry *dentry);
 extern int register_cld_notifier(void);