locks: prevent ENOMEM on lease unlock

Removing a lock shouldn't require any allocations; a failure due to ENOMEM leaves the caller with a choice between retrying or giving up and leaking an unused lease. Next we should split the other lease calls into add and delete cases. I wanted to start with just the bugfix. Signed-off-by: J. Bruce Fields <bfields@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

locks: prevent ENOMEM on lease unlock
Removing a lock shouldn't require any allocations; a failure due to ENOMEM leaves the caller with a choice between retrying or giving up and leaking an unused lease. Next we should split the other lease calls into add and delete cases. I wanted to start with just the bugfix. Signed-off-by: J. Bruce Fields <bfields@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
J. Bruce Fields · Linus Torvalds
1 parent 0d07025eff
Showing 1 changed file with 30 additions and 13 deletions Side-by-side Diff
fs/locks.c
@@ -1441,7 +1441,8 @@
 	return 0;
  
 out:
-	locks_free_lock(lease);
+	if (arg != F_UNLCK)
+		locks_free_lock(lease);
 	return error;
 }
 EXPORT_SYMBOL(generic_setlease);
  
@@ -1493,18 +1494,17 @@
 }
 EXPORT_SYMBOL_GPL(vfs_setlease);
  
-/**
- *	fcntl_setlease	-	sets a lease on an open file
- *	@fd: open file descriptor
- *	@filp: file pointer
- *	@arg: type of lease to obtain
- *
- *	Call this fcntl to establish a lease on the file.
- *	Note that you also need to call %F_SETSIG to
- *	receive a signal when the lease is broken.
- */
-int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
+static int do_fcntl_delete_lease(struct file *filp)
 {
+	struct file_lock fl, *flp = &fl;
+
+	lease_init(filp, F_UNLCK, flp);
+
+	return vfs_setlease(filp, F_UNLCK, &flp);
+}
+
+static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
+{
 	struct file_lock *fl;
 	struct fasync_struct *new;
 	struct inode *inode = filp->f_path.dentry->d_inode;
@@ -1521,7 +1521,7 @@
 	}
 	lock_flocks();
 	error = __vfs_setlease(filp, arg, &fl);
-	if (error || arg == F_UNLCK)
+	if (error)
 		goto out_unlock;
  
 	/*
@@ -1547,6 +1547,23 @@
 	if (new)
 		fasync_free(new);
 	return error;
+}
+
+/**
+ *	fcntl_setlease	-	sets a lease on an open file
+ *	@fd: open file descriptor
+ *	@filp: file pointer
+ *	@arg: type of lease to obtain
+ *
+ *	Call this fcntl to establish a lease on the file.
+ *	Note that you also need to call %F_SETSIG to
+ *	receive a signal when the lease is broken.
+ */
+int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
+{
+	if (arg == F_UNLCK)
+		return do_fcntl_delete_lease(filp);
+	return do_fcntl_add_lease(fd, filp, arg);
 }
  
 /**
...	...	@@ -1441,7 +1441,8 @@
1441	1441	return 0;
1442	1442
1443	1443	out:
1444		- locks_free_lock(lease);
	1444	+ if (arg != F_UNLCK)
	1445	+ locks_free_lock(lease);
1445	1446	return error;
1446	1447	}
1447	1448	EXPORT_SYMBOL(generic_setlease);
1448	1449
...	...	@@ -1493,18 +1494,17 @@
1493	1494	}
1494	1495	EXPORT_SYMBOL_GPL(vfs_setlease);
1495	1496
1496		-/**
1497		- * fcntl_setlease - sets a lease on an open file
1498		- * @fd: open file descriptor
1499		- * @filp: file pointer
1500		- * @arg: type of lease to obtain
1501		- *
1502		- * Call this fcntl to establish a lease on the file.
1503		- * Note that you also need to call %F_SETSIG to
1504		- * receive a signal when the lease is broken.
1505		- */
1506		-int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
	1497	+static int do_fcntl_delete_lease(struct file *filp)
1507	1498	{
	1499	+ struct file_lock fl, *flp = &fl;
	1500	+
	1501	+ lease_init(filp, F_UNLCK, flp);
	1502	+
	1503	+ return vfs_setlease(filp, F_UNLCK, &flp);
	1504	+}
	1505	+
	1506	+static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
	1507	+{
1508	1508	struct file_lock *fl;
1509	1509	struct fasync_struct *new;
1510	1510	struct inode *inode = filp->f_path.dentry->d_inode;
...	...	@@ -1521,7 +1521,7 @@
1521	1521	}
1522	1522	lock_flocks();
1523	1523	error = __vfs_setlease(filp, arg, &fl);
1524		- if (error \|\| arg == F_UNLCK)
	1524	+ if (error)
1525	1525	goto out_unlock;
1526	1526
1527	1527	/*
...	...	@@ -1547,6 +1547,23 @@
1547	1547	if (new)
1548	1548	fasync_free(new);
1549	1549	return error;
	1550	+}
	1551	+
	1552	+/**
	1553	+ * fcntl_setlease - sets a lease on an open file
	1554	+ * @fd: open file descriptor
	1555	+ * @filp: file pointer
	1556	+ * @arg: type of lease to obtain
	1557	+ *
	1558	+ * Call this fcntl to establish a lease on the file.
	1559	+ * Note that you also need to call %F_SETSIG to
	1560	+ * receive a signal when the lease is broken.
	1561	+ */
	1562	+int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
	1563	+{
	1564	+ if (arg == F_UNLCK)
	1565	+ return do_fcntl_delete_lease(filp);
	1566	+ return do_fcntl_add_lease(fd, filp, arg);
1550	1567	}
1551	1568
1552	1569	/**