dnotify: Pass argument of fcntl_dirnotify as int

The interface for fcntl expects the argument passed for the command
F_DIRNOTIFY to be of type int. The current code wrongly treats it as
a long. In order to avoid access to undefined bits, we should explicitly
cast the argument to int.

Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Kevin Brodsky <Kevin.Brodsky@arm.com>
Cc: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Cc: Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: David Laight <David.Laight@ACULAB.com>
Cc: Mark Rutland <Mark.Rutland@arm.com>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-morello@op-lists.linaro.org
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Luca Vizzarro <Luca.Vizzarro@arm.com>
Message-Id: <20230414152459.816046-6-Luca.Vizzarro@arm.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/notify/dnotify/dnotify.c

@@ -199,7 +199,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
 }
 
 /* this conversion is done only at watch creation */
-static __u32 convert_arg(unsigned long arg)
+static __u32 convert_arg(unsigned int arg)
 {
 	__u32 new_mask = FS_EVENT_ON_CHILD;
 
@@ -258,7 +258,7 @@ static int attach_dn(struct dnotify_struct *dn, struct dnotify_mark *dn_mark,
  * up here.  Allocate both a mark for fsnotify to add and a dnotify_struct to be
  * attached to the fsnotify_mark.
  */
-int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
+int fcntl_dirnotify(int fd, struct file *filp, unsigned int arg)
 {
 	struct dnotify_mark *new_dn_mark, *dn_mark;
 	struct fsnotify_mark *new_fsn_mark, *fsn_mark;

include/linux/dnotify.h

@@ -30,7 +30,7 @@ struct dnotify_struct {
 			    FS_MOVED_FROM | FS_MOVED_TO)
 
 extern void dnotify_flush(struct file *, fl_owner_t);
-extern int fcntl_dirnotify(int, struct file *, unsigned long);
+extern int fcntl_dirnotify(int, struct file *, unsigned int);
 
 #else
 
@@ -38,7 +38,7 @@ static inline void dnotify_flush(struct file *filp, fl_owner_t id)
 {
 }
 
-static inline int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
+static inline int fcntl_dirnotify(int fd, struct file *filp, unsigned int arg)
 {
 	return -EINVAL;
 }