fsnotify: make allow_dups a property of the group

Instead of passing the allow_dups argument to fsnotify_add_mark()
as an argument, define the group flag FSNOTIFY_GROUP_DUPS to express
the allow_dups behavior and set this behavior at group creation time
for all calls of fsnotify_add_mark().

Rename the allow_dups argument to generic add_flags argument for future
use.

Link: https://lore.kernel.org/r/20220422120327.3459282-6-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/mark.c

@@ -574,7 +574,7 @@ out:
 static int fsnotify_add_mark_list(struct fsnotify_mark *mark,
 				  fsnotify_connp_t *connp,
 				  unsigned int obj_type,
-				  int allow_dups, __kernel_fsid_t *fsid)
+				  int add_flags, __kernel_fsid_t *fsid)
 {
 	struct fsnotify_mark *lmark, *last = NULL;
 	struct fsnotify_mark_connector *conn;
@@ -633,7 +633,7 @@ restart:
 
 		if ((lmark->group == mark->group) &&
 		    (lmark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) &&
-		    !allow_dups) {
+		    !(mark->group->flags & FSNOTIFY_GROUP_DUPS)) {
 			err = -EEXIST;
 			goto out_err;
 		}
@@ -668,7 +668,7 @@ out_err:
  */
 int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
 			     fsnotify_connp_t *connp, unsigned int obj_type,
-			     int allow_dups, __kernel_fsid_t *fsid)
+			     int add_flags, __kernel_fsid_t *fsid)
 {
 	struct fsnotify_group *group = mark->group;
 	int ret = 0;
@@ -688,7 +688,7 @@ int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
 	fsnotify_get_mark(mark); /* for g_list */
 	spin_unlock(&mark->lock);
 
-	ret = fsnotify_add_mark_list(mark, connp, obj_type, allow_dups, fsid);
+	ret = fsnotify_add_mark_list(mark, connp, obj_type, add_flags, fsid);
 	if (ret)
 		goto err;
 
@@ -708,14 +708,14 @@ err:
 }
 
 int fsnotify_add_mark(struct fsnotify_mark *mark, fsnotify_connp_t *connp,
-		      unsigned int obj_type, int allow_dups,
+		      unsigned int obj_type, int add_flags,
 		      __kernel_fsid_t *fsid)
 {
 	int ret;
 	struct fsnotify_group *group = mark->group;
 
 	mutex_lock(&group->mark_mutex);
-	ret = fsnotify_add_mark_locked(mark, connp, obj_type, allow_dups, fsid);
+	ret = fsnotify_add_mark_locked(mark, connp, obj_type, add_flags, fsid);
 	mutex_unlock(&group->mark_mutex);
 	return ret;
 }

include/linux/fsnotify_backend.h

@@ -211,6 +211,7 @@ struct fsnotify_group {
 	bool shutdown;		/* group is being shut down, don't queue more events */
 
 #define FSNOTIFY_GROUP_USER	0x01 /* user allocated group */
+#define FSNOTIFY_GROUP_DUPS	0x02 /* allow multiple marks per object */
 	int flags;
 
 	/* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
@@ -641,26 +642,26 @@ extern int fsnotify_get_conn_fsid(const struct fsnotify_mark_connector *conn,
 /* attach the mark to the object */
 extern int fsnotify_add_mark(struct fsnotify_mark *mark,
 			     fsnotify_connp_t *connp, unsigned int obj_type,
-			     int allow_dups, __kernel_fsid_t *fsid);
+			     int add_flags, __kernel_fsid_t *fsid);
 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
 				    fsnotify_connp_t *connp,
-				    unsigned int obj_type, int allow_dups,
+				    unsigned int obj_type, int add_flags,
 				    __kernel_fsid_t *fsid);
 
 /* attach the mark to the inode */
 static inline int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
 					  struct inode *inode,
-					  int allow_dups)
+					  int add_flags)
 {
 	return fsnotify_add_mark(mark, &inode->i_fsnotify_marks,
-				 FSNOTIFY_OBJ_TYPE_INODE, allow_dups, NULL);
+				 FSNOTIFY_OBJ_TYPE_INODE, add_flags, NULL);
 }
 static inline int fsnotify_add_inode_mark_locked(struct fsnotify_mark *mark,
 						 struct inode *inode,
-						 int allow_dups)
+						 int add_flags)
 {
 	return fsnotify_add_mark_locked(mark, &inode->i_fsnotify_marks,
-					FSNOTIFY_OBJ_TYPE_INODE, allow_dups,
+					FSNOTIFY_OBJ_TYPE_INODE, add_flags,
 					NULL);
 }
 

kernel/audit_fsnotify.c

@@ -100,7 +100,7 @@ struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pa
 	audit_update_mark(audit_mark, dentry->d_inode);
 	audit_mark->rule = krule;
 
-	ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, true);
+	ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, 0);
 	if (ret < 0) {
 		fsnotify_put_mark(&audit_mark->mark);
 		audit_mark = ERR_PTR(ret);
@@ -182,7 +182,7 @@ static const struct fsnotify_ops audit_mark_fsnotify_ops = {
 static int __init audit_fsnotify_init(void)
 {
 	audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops,
-						    0);
+						    FSNOTIFY_GROUP_DUPS);
 	if (IS_ERR(audit_fsnotify_group)) {
 		audit_fsnotify_group = NULL;
 		audit_panic("cannot create audit fsnotify group");