locks: introduce new FL_DELEG lock flag

For now FL_DELEG is just a synonym for FL_LEASE.  So this patch doesn't
change behavior.

Next we'll modify break_lease to treat FL_DELEG leases differently, to
account for the fact that NFSv4 delegations should be broken in more
situations than Windows oplocks.

Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/locks.c

@@ -134,7 +134,7 @@
 
 #define IS_POSIX(fl)	(fl->fl_flags & FL_POSIX)
 #define IS_FLOCK(fl)	(fl->fl_flags & FL_FLOCK)
-#define IS_LEASE(fl)	(fl->fl_flags & FL_LEASE)
+#define IS_LEASE(fl)	(fl->fl_flags & (FL_LEASE|FL_DELEG))
 
 static bool lease_breaking(struct file_lock *fl)
 {

fs/nfsd/nfs4state.c

@@ -3008,7 +3008,7 @@ static struct file_lock *nfs4_alloc_init_lease(struct nfs4_delegation *dp, int f
 		return NULL;
 	locks_init_lock(fl);
 	fl->fl_lmops = &nfsd_lease_mng_ops;
-	fl->fl_flags = FL_LEASE;
+	fl->fl_flags = FL_DELEG;
 	fl->fl_type = flag == NFS4_OPEN_DELEGATE_READ? F_RDLCK: F_WRLCK;
 	fl->fl_end = OFFSET_MAX;
 	fl->fl_owner = (fl_owner_t)(dp->dl_file);

include/linux/fs.h

@@ -880,6 +880,7 @@ static inline int file_check_writeable(struct file *filp)
 
 #define FL_POSIX	1
 #define FL_FLOCK	2
+#define FL_DELEG	4	/* NFSv4 delegation */
 #define FL_ACCESS	8	/* not trying to lock, just looking */
 #define FL_EXISTS	16	/* when unlocking, test for existence */
 #define FL_LEASE	32	/* lease held on this file */