NFSv4: Add a capability for delegated attributes

Cache whether or not the server may have support for delegated
attributes in a capability flag.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4proc.c

@@ -3930,6 +3930,8 @@ static int _nfs4_server_capabilities(struct nfs_server *server, struct nfs_fh *f
 #endif
 		if (res.attr_bitmask[0] & FATTR4_WORD0_FS_LOCATIONS)
 			server->caps |= NFS_CAP_FS_LOCATIONS;
+		if (res.attr_bitmask[2] & FATTR4_WORD2_TIME_DELEG_MODIFY)
+			server->caps |= NFS_CAP_DELEGTIME;
 		if (!(res.attr_bitmask[0] & FATTR4_WORD0_FILEID))
 			server->fattr_valid &= ~NFS_ATTR_FATTR_FILEID;
 		if (!(res.attr_bitmask[1] & FATTR4_WORD1_MODE))

include/linux/nfs_fs_sb.h

@@ -278,6 +278,7 @@ struct nfs_server {
 #define NFS_CAP_LGOPEN		(1U << 5)
 #define NFS_CAP_CASE_INSENSITIVE	(1U << 6)
 #define NFS_CAP_CASE_PRESERVING	(1U << 7)
+#define NFS_CAP_DELEGTIME	(1U << 13)
 #define NFS_CAP_POSIX_LOCK	(1U << 14)
 #define NFS_CAP_UIDGID_NOMAP	(1U << 15)
 #define NFS_CAP_STATEID_NFSV41	(1U << 16)