locks: implement delegations

Implement NFSv4 delegations at the vfs level using the new FL_DELEG lock
type.

Note nfsd is the only delegation user and is only using read
delegations.  Warn on any attempt to set a write delegation for now.
We'll come back to that case later.

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>

1 files changed, 15 insertions, 3 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 129e150f9e94..8e4be1be1a62 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1022,7 +1022,7 @@ extern int vfs_test_lock(struct file *, struct file_lock *);
 extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);
 extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);
 extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl);
-extern int __break_lease(struct inode *inode, unsigned int flags);
+extern int __break_lease(struct inode *inode, unsigned int flags, unsigned int type);
 extern void lease_get_mtime(struct inode *, struct timespec *time);
 extern int generic_setlease(struct file *, long, struct file_lock **);
 extern int vfs_setlease(struct file *, long, struct file_lock **);
@@ -1131,7 +1131,7 @@ static inline int flock_lock_file_wait(struct file *filp,
         return -ENOLCK;
 }
 
-static inline int __break_lease(struct inode *inode, unsigned int mode)
+static inline int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
 {
         return 0;
 }
@@ -1961,9 +1961,17 @@ static inline int locks_verify_truncate(struct inode *inode,
 static inline int break_lease(struct inode *inode, unsigned int mode)
 {
         if (inode->i_flock)
-                return __break_lease(inode, mode);
+                return __break_lease(inode, mode, FL_LEASE);
         return 0;
 }
+
+static inline int break_deleg(struct inode *inode, unsigned int mode)
+{
+        if (inode->i_flock)
+                return __break_lease(inode, mode, FL_DELEG);
+        return 0;
+}
+
 #else /* !CONFIG_FILE_LOCKING */
 static inline int locks_mandatory_locked(struct inode *inode)
 {
@@ -2003,6 +2011,10 @@ static inline int break_lease(struct inode *inode, unsigned int mode)
         return 0;
 }
 
+static inline int break_deleg(struct inode *inode, unsigned int mode)
+{
+        return 0;
+}
 #endif /* CONFIG_FILE_LOCKING */
 
 /* fs/open.c */