fsnotify: Pass fsnotify_iter_info into handle_event handler

Pass fsnotify_iter_info into ->handle_event() handler so that it can
release and reacquire SRCU lock via fsnotify_prepare_user_wait() and
fsnotify_finish_user_wait() functions.  These functions also make sure
current marks are appropriately pinned so that iteration protected by
srcu in fsnotify() stays safe.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/dnotify/dnotify.c

@@ -85,7 +85,8 @@ static int dnotify_handle_event(struct fsnotify_group *group,
 				struct fsnotify_mark *inode_mark,
 				struct fsnotify_mark *vfsmount_mark,
 				u32 mask, const void *data, int data_type,
-				const unsigned char *file_name, u32 cookie)
+				const unsigned char *file_name, u32 cookie,
+				struct fsnotify_iter_info *iter_info)
 {
 	struct dnotify_mark *dn_mark;
 	struct dnotify_struct *dn;

fs/notify/fanotify/fanotify.c

@@ -174,7 +174,8 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 				 struct fsnotify_mark *inode_mark,
 				 struct fsnotify_mark *fanotify_mark,
 				 u32 mask, const void *data, int data_type,
-				 const unsigned char *file_name, u32 cookie)
+				 const unsigned char *file_name, u32 cookie,
+				 struct fsnotify_iter_info *iter_info)
 {
 	int ret = 0;
 	struct fanotify_event_info *event;

fs/notify/fsnotify.c

@@ -127,7 +127,8 @@ static int send_to_group(struct inode *to_tell,
 			 struct fsnotify_mark *vfsmount_mark,
 			 __u32 mask, const void *data,
 			 int data_is, u32 cookie,
-			 const unsigned char *file_name)
+			 const unsigned char *file_name,
+			 struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_group *group = NULL;
 	__u32 inode_test_mask = 0;
@@ -178,7 +179,7 @@ static int send_to_group(struct inode *to_tell,
 
 	return group->ops->handle_event(group, to_tell, inode_mark,
 					vfsmount_mark, mask, data, data_is,
-					file_name, cookie);
+					file_name, cookie, iter_info);
 }
 
 /*
@@ -194,8 +195,9 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL;
 	struct fsnotify_group *inode_group, *vfsmount_group;
 	struct fsnotify_mark_connector *inode_conn, *vfsmount_conn;
+	struct fsnotify_iter_info iter_info;
 	struct mount *mnt;
-	int idx, ret = 0;
+	int ret = 0;
 	/* global tests shouldn't care about events on child only the specific event */
 	__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
 
@@ -224,7 +226,7 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	    !(mnt && test_mask & mnt->mnt_fsnotify_mask))
 		return 0;
 
-	idx = srcu_read_lock(&fsnotify_mark_srcu);
+	iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
 
 	if ((mask & FS_MODIFY) ||
 	    (test_mask & to_tell->i_fsnotify_mask)) {
@@ -284,8 +286,13 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 				vfsmount_mark = NULL;
 			}
 		}
+
+		iter_info.inode_mark = inode_mark;
+		iter_info.vfsmount_mark = vfsmount_mark;
+
 		ret = send_to_group(to_tell, inode_mark, vfsmount_mark, mask,
-				    data, data_is, cookie, file_name);
+				    data, data_is, cookie, file_name,
+				    &iter_info);
 
 		if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
 			goto out;
@@ -299,7 +306,7 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	}
 	ret = 0;
 out:
-	srcu_read_unlock(&fsnotify_mark_srcu, idx);
+	srcu_read_unlock(&fsnotify_mark_srcu, iter_info.srcu_idx);
 
 	return ret;
 }

fs/notify/inotify/inotify.h

@@ -27,7 +27,8 @@ extern int inotify_handle_event(struct fsnotify_group *group,
 				struct fsnotify_mark *inode_mark,
 				struct fsnotify_mark *vfsmount_mark,
 				u32 mask, const void *data, int data_type,
-				const unsigned char *file_name, u32 cookie);
+				const unsigned char *file_name, u32 cookie,
+				struct fsnotify_iter_info *iter_info);
 
 extern const struct fsnotify_ops inotify_fsnotify_ops;
 

fs/notify/inotify/inotify_fsnotify.c

@@ -68,7 +68,8 @@ int inotify_handle_event(struct fsnotify_group *group,
 			 struct fsnotify_mark *inode_mark,
 			 struct fsnotify_mark *vfsmount_mark,
 			 u32 mask, const void *data, int data_type,
-			 const unsigned char *file_name, u32 cookie)
+			 const unsigned char *file_name, u32 cookie,
+			 struct fsnotify_iter_info *iter_info)
 {
 	struct inotify_inode_mark *i_mark;
 	struct inotify_event_info *event;

fs/notify/inotify/inotify_user.c

@@ -474,7 +474,7 @@ void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
 
 	/* Queue ignore event for the watch */
 	inotify_handle_event(group, NULL, fsn_mark, NULL, FS_IN_IGNORED,
-			     NULL, FSNOTIFY_EVENT_NONE, NULL, 0);
+			     NULL, FSNOTIFY_EVENT_NONE, NULL, 0, NULL);
 
 	i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 	/* remove this mark from the idr */

include/linux/fsnotify_backend.h

@@ -99,7 +99,8 @@ struct fsnotify_ops {
 			    struct fsnotify_mark *inode_mark,
 			    struct fsnotify_mark *vfsmount_mark,
 			    u32 mask, const void *data, int data_type,
-			    const unsigned char *file_name, u32 cookie);
+			    const unsigned char *file_name, u32 cookie,
+			    struct fsnotify_iter_info *iter_info);
 	void (*free_group_priv)(struct fsnotify_group *group);
 	void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
 	void (*free_event)(struct fsnotify_event *event);

kernel/audit_fsnotify.c

@@ -168,7 +168,8 @@ static int audit_mark_handle_event(struct fsnotify_group *group,
 				    struct fsnotify_mark *inode_mark,
 				    struct fsnotify_mark *vfsmount_mark,
 				    u32 mask, const void *data, int data_type,
-				    const unsigned char *dname, u32 cookie)
+				    const unsigned char *dname, u32 cookie,
+				    struct fsnotify_iter_info *iter_info)
 {
 	struct audit_fsnotify_mark *audit_mark;
 	const struct inode *inode = NULL;

kernel/audit_tree.c

@@ -989,7 +989,8 @@ static int audit_tree_handle_event(struct fsnotify_group *group,
 				   struct fsnotify_mark *inode_mark,
 				   struct fsnotify_mark *vfsmount_mark,
 				   u32 mask, const void *data, int data_type,
-				   const unsigned char *file_name, u32 cookie)
+				   const unsigned char *file_name, u32 cookie,
+				   struct fsnotify_iter_info *iter_info)
 {
 	return 0;
 }

kernel/audit_watch.c

@@ -472,7 +472,8 @@ static int audit_watch_handle_event(struct fsnotify_group *group,
 				    struct fsnotify_mark *inode_mark,
 				    struct fsnotify_mark *vfsmount_mark,
 				    u32 mask, const void *data, int data_type,
-				    const unsigned char *dname, u32 cookie)
+				    const unsigned char *dname, u32 cookie,
+				    struct fsnotify_iter_info *iter_info)
 {
 	const struct inode *inode;
 	struct audit_parent *parent;