locks: Copy fl_lmops information for conflock in locks_copy_conflock()

Commit d5b9026a ([PATCH] knfsd: locks: flag NFSv4-owned locks) using
fl_lmops field in file_lock for checking nfsd4 lockowner.

But, commit 1a747ee0 (locks: don't call ->copy_lock methods on return
of conflicting locks) causes the fl_lmops of conflock always be NULL.

Also, commit 0996905f (lockd: posix_test_lock() should not call
locks_copy_lock()) caused the fl_lmops of conflock always be NULL too.

Make sure copy the private information by fl_copy_lock() in struct
file_lock_operations, merge __locks_copy_lock() to fl_copy_lock().

Jeff advice, "Set fl_lmops on conflocks, but don't set fl_ops.
fl_ops are superfluous, since they are callbacks into the filesystem.
There should be no need to bother the filesystem at all with info
in a conflock. But, lock _ownership_ matters for conflocks and that's
indicated by the fl_lmops. So you really do want to copy the fl_lmops
for conflocks I think."

v5: add missing calling of locks_release_private() in nlmsvc_testlock()
v4: only copy fl_lmops for conflock, don't copy fl_ops
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>

fs/lockd/svclock.c

@@ -586,6 +586,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 	conflock->fl.fl_type = lock->fl.fl_type;
 	conflock->fl.fl_start = lock->fl.fl_start;
 	conflock->fl.fl_end = lock->fl.fl_end;
+	locks_release_private(&lock->fl);
 	ret = nlm_lck_denied;
 out:
 	if (block)

fs/locks.c

@@ -271,21 +271,6 @@ void locks_init_lock(struct file_lock *fl)
 
 EXPORT_SYMBOL(locks_init_lock);
 
-static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
-{
-	if (fl->fl_ops) {
-		if (fl->fl_ops->fl_copy_lock)
-			fl->fl_ops->fl_copy_lock(new, fl);
-		new->fl_ops = fl->fl_ops;
-	}
-
-	if (fl->fl_lmops) {
-		if (fl->fl_lmops->lm_get_owner)
-			fl->fl_lmops->lm_get_owner(new, fl);
-		new->fl_lmops = fl->fl_lmops;
-	}
-}
-
 /*
  * Initialize a new lock from an existing file_lock structure.
  */
@@ -298,8 +283,13 @@ void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
 	new->fl_type = fl->fl_type;
 	new->fl_start = fl->fl_start;
 	new->fl_end = fl->fl_end;
+	new->fl_lmops = fl->fl_lmops;
 	new->fl_ops = NULL;
-	new->fl_lmops = NULL;
+
+	if (fl->fl_lmops) {
+		if (fl->fl_lmops->lm_get_owner)
+			fl->fl_lmops->lm_get_owner(new, fl);
+	}
 }
 EXPORT_SYMBOL(locks_copy_conflock);
 
@@ -309,11 +299,14 @@ void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 	WARN_ON_ONCE(new->fl_ops);
 
 	locks_copy_conflock(new, fl);
+
 	new->fl_file = fl->fl_file;
 	new->fl_ops = fl->fl_ops;
-	new->fl_lmops = fl->fl_lmops;
 
-	locks_copy_private(new, fl);
+	if (fl->fl_ops) {
+		if (fl->fl_ops->fl_copy_lock)
+			fl->fl_ops->fl_copy_lock(new, fl);
+	}
 }
 
 EXPORT_SYMBOL(locks_copy_lock);
@@ -1989,11 +1982,13 @@ int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l)
 	if (file_lock.fl_type != F_UNLCK) {
 		error = posix_lock_to_flock(&flock, &file_lock);
 		if (error)
-			goto out;
+			goto rel_priv;
 	}
 	error = -EFAULT;
 	if (!copy_to_user(l, &flock, sizeof(flock)))
 		error = 0;
+rel_priv:
+	locks_release_private(&file_lock);
 out:
 	return error;
 }
@@ -2214,7 +2209,8 @@ int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
 	error = -EFAULT;
 	if (!copy_to_user(l, &flock, sizeof(flock)))
 		error = 0;
-  
+
+	locks_release_private(&file_lock);
 out:
 	return error;
 }