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From:   Gabriel Krisman Bertazi <krisman@collabora.com>
To:     amir73il@gmail.com
Cc:     djwong@kernel.org, tytso@mit.edu, david@fromorbit.com,
        jack@suse.com, dhowells@redhat.com, khazhy@google.com,
        linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
        kernel@collabora.com,
        Gabriel Krisman Bertazi <krisman@collabora.com>
Subject: [PATCH v3 07/15] fsnotify: pass arguments of fsnotify() in struct fsnotify_event_info
Date:   Tue, 29 Jun 2021 15:10:27 -0400
Message-Id: <20210629191035.681913-8-krisman@collabora.com>
In-Reply-To: <20210629191035.681913-1-krisman@collabora.com>
References: <20210629191035.681913-1-krisman@collabora.com>
MIME-Version: 1.0
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From: Amir Goldstein <amir73il@gmail.com>

There are a lot of arguments to fsnotify() and the handle_event() method.
Pass them in a const struct instead of on the argument list.

Apart from being more tidy, this helps with passing error reports to the
backend.  __fsnotify_parent() argument list was intentionally left
untouched, because its argument list is still short enough and because
most of the event info arguments are initialized inside
__fsnotify_parent().

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
---
 fs/notify/fanotify/fanotify.c    | 59 +++++++++++------------
 fs/notify/fsnotify.c             | 83 +++++++++++++++++---------------
 include/linux/fsnotify.h         | 15 ++++--
 include/linux/fsnotify_backend.h | 73 +++++++++++++++++++++-------
 4 files changed, 140 insertions(+), 90 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 0f760770d4c9..4f2febb15e94 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -253,21 +253,22 @@ static int fanotify_get_response(struct fsnotify_group *group,
  * been included within the event mask, but have not been explicitly
  * requested by the user, will not be present in the returned mask.
  */
-static u32 fanotify_group_event_mask(struct fsnotify_group *group,
-				     struct fsnotify_iter_info *iter_info,
-				     u32 event_mask, const void *data,
-				     int data_type, struct inode *dir)
+static u32 fanotify_group_event_mask(
+				struct fsnotify_group *group, u32 event_mask,
+				const struct fsnotify_event_info *event_info,
+				struct fsnotify_iter_info *iter_info)
 {
 	__u32 marks_mask = 0, marks_ignored_mask = 0;
 	__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS |
 				     FANOTIFY_EVENT_FLAGS;
-	const struct path *path = fsnotify_data_path(data, data_type);
+	const struct path *path = fsnotify_event_info_path(event_info);
 	unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
 	struct fsnotify_mark *mark;
 	int type;
 
 	pr_debug("%s: report_mask=%x mask=%x data=%p data_type=%d\n",
-		 __func__, iter_info->report_mask, event_mask, data, data_type);
+		 __func__, iter_info->report_mask, event_mask,
+		 event_info->data, event_info->data_type);
 
 	if (!fid_mode) {
 		/* Do we have path to open a file descriptor? */
@@ -278,7 +279,7 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
 			return 0;
 	} else if (!(fid_mode & FAN_REPORT_FID)) {
 		/* Do we have a directory inode to report? */
-		if (!dir && !(event_mask & FS_ISDIR))
+		if (!event_info->dir && !(event_mask & FS_ISDIR))
 			return 0;
 	}
 
@@ -427,13 +428,13 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
  * FS_ATTRIB reports the child inode even if reported on a watched parent.
  * FS_CREATE reports the modified dir inode and not the created inode.
  */
-static struct inode *fanotify_fid_inode(u32 event_mask, const void *data,
-					int data_type, struct inode *dir)
+static struct inode *fanotify_fid_inode(u32 event_mask,
+				const struct fsnotify_event_info *event_info)
 {
 	if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)
-		return dir;
+		return event_info->dir;
 
-	return fsnotify_data_inode(data, data_type);
+	return fsnotify_event_info_inode(event_info);
 }
 
 /*
@@ -444,18 +445,18 @@ static struct inode *fanotify_fid_inode(u32 event_mask, const void *data,
  * reported to parent.
  * Otherwise, do not report dir fid.
  */
-static struct inode *fanotify_dfid_inode(u32 event_mask, const void *data,
-					 int data_type, struct inode *dir)
+static struct inode *fanotify_dfid_inode(u32 event_mask,
+				const struct fsnotify_event_info *event_info)
 {
-	struct inode *inode = fsnotify_data_inode(data, data_type);
+	struct inode *inode = fsnotify_event_info_inode(event_info);
 
 	if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)
-		return dir;
+		return event_info->dir;
 
 	if (S_ISDIR(inode->i_mode))
 		return inode;
 
-	return dir;
+	return event_info->dir;
 }
 
 static struct fanotify_event *fanotify_alloc_path_event(const struct path *path,
@@ -563,17 +564,17 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
 	return &fne->fae;
 }
 
-static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
-						   u32 mask, const void *data,
-						   int data_type, struct inode *dir,
-						   const struct qstr *file_name,
-						   __kernel_fsid_t *fsid)
+static struct fanotify_event *fanotify_alloc_event(
+				struct fsnotify_group *group, u32 mask,
+				const struct fsnotify_event_info *event_info,
+				__kernel_fsid_t *fsid)
 {
 	struct fanotify_event *event = NULL;
 	gfp_t gfp = GFP_KERNEL_ACCOUNT;
-	struct inode *id = fanotify_fid_inode(mask, data, data_type, dir);
-	struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir);
-	const struct path *path = fsnotify_data_path(data, data_type);
+	struct inode *id = fanotify_fid_inode(mask, event_info);
+	struct inode *dirid = fanotify_dfid_inode(mask, event_info);
+	const struct path *path = fsnotify_event_info_path(event_info);
+	const struct qstr *file_name = event_info->name;
 	unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
 	struct mem_cgroup *old_memcg;
 	struct inode *child = NULL;
@@ -712,9 +713,7 @@ static void fanotify_insert_event(struct fsnotify_group *group,
 }
 
 static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
-				 const void *data, int data_type,
-				 struct inode *dir,
-				 const struct qstr *file_name, u32 cookie,
+				 const struct fsnotify_event_info *event_info,
 				 struct fsnotify_iter_info *iter_info)
 {
 	int ret = 0;
@@ -744,8 +743,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
 
 	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
 
-	mask = fanotify_group_event_mask(group, iter_info, mask, data,
-					 data_type, dir);
+	mask = fanotify_group_event_mask(group, mask, event_info, iter_info);
 	if (!mask)
 		return 0;
 
@@ -767,8 +765,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
 			return 0;
 	}
 
-	event = fanotify_alloc_event(group, mask, data, data_type, dir,
-				     file_name, &fsid);
+	event = fanotify_alloc_event(group, mask, event_info, &fsid);
 	ret = -ENOMEM;
 	if (unlikely(!event)) {
 		/*
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 30d422b8c0fc..36205a769dde 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -177,8 +177,8 @@ static bool fsnotify_event_needs_parent(struct inode *inode, struct mount *mnt,
  * Notify only the child without name info if parent is not watching and
  * inode/sb/mount are not interested in events with parent and name info.
  */
-int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
-		      int data_type)
+int __fsnotify_parent(struct dentry *dentry, __u32 mask,
+		      const void *data, int data_type)
 {
 	const struct path *path = fsnotify_data_path(data, data_type);
 	struct mount *mnt = path ? real_mount(path->mnt) : NULL;
@@ -229,7 +229,11 @@ int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
 	}
 
 notify:
-	ret = fsnotify(mask, data, data_type, p_inode, file_name, inode, 0);
+	ret = __fsnotify(mask, &(struct fsnotify_event_info) {
+				.data = data, .data_type = data_type,
+				.dir = p_inode, .name = file_name,
+				.inode = inode,
+				});
 
 	if (file_name)
 		release_dentry_name_snapshot(&name);
@@ -240,13 +244,11 @@ int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
 EXPORT_SYMBOL_GPL(__fsnotify_parent);
 
 static int fsnotify_handle_inode_event(struct fsnotify_group *group,
-				       struct fsnotify_mark *inode_mark,
-				       u32 mask, const void *data, int data_type,
-				       struct inode *dir, const struct qstr *name,
-				       u32 cookie)
+			       struct fsnotify_mark *inode_mark, u32 mask,
+			       const struct fsnotify_event_info *event_info)
 {
-	const struct path *path = fsnotify_data_path(data, data_type);
-	struct inode *inode = fsnotify_data_inode(data, data_type);
+	const struct path *path = fsnotify_event_info_path(event_info);
+	struct inode *inode = fsnotify_event_info_inode(event_info);
 	const struct fsnotify_ops *ops = group->ops;
 
 	if (WARN_ON_ONCE(!ops->handle_inode_event))
@@ -260,16 +262,17 @@ static int fsnotify_handle_inode_event(struct fsnotify_group *group,
 	if (!(mask & inode_mark->mask & ALL_FSNOTIFY_EVENTS))
 		return 0;
 
-	return ops->handle_inode_event(inode_mark, mask, inode, dir, name, cookie);
+	return ops->handle_inode_event(inode_mark, mask, inode, event_info->dir,
+				       event_info->name, event_info->cookie);
 }
 
 static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask,
-				 const void *data, int data_type,
-				 struct inode *dir, const struct qstr *name,
-				 u32 cookie, struct fsnotify_iter_info *iter_info)
+				 const struct fsnotify_event_info *event_info,
+				 struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
 	struct fsnotify_mark *parent_mark = fsnotify_iter_parent_mark(iter_info);
+	struct fsnotify_event_info child_event_info = { };
 	int ret;
 
 	if (WARN_ON_ONCE(fsnotify_iter_sb_mark(iter_info)) ||
@@ -284,8 +287,8 @@ static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask,
 		 * interested in this event?
 		 */
 		if (parent_mark->mask & FS_EVENT_ON_CHILD) {
-			ret = fsnotify_handle_inode_event(group, parent_mark, mask,
-							  data, data_type, dir, name, 0);
+			ret = fsnotify_handle_inode_event(group, parent_mark,
+							  mask, event_info);
 			if (ret)
 				return ret;
 		}
@@ -302,18 +305,22 @@ static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask,
 		 * The child watcher is expecting an event without a file name
 		 * and without the FS_EVENT_ON_CHILD flag.
 		 */
+		if (WARN_ON_ONCE(!event_info->inode))
+			return 0;
+
 		mask &= ~FS_EVENT_ON_CHILD;
-		dir = NULL;
-		name = NULL;
+		child_event_info = *event_info;
+		child_event_info.dir = NULL;
+		child_event_info.name = NULL;
+		event_info = &child_event_info;
 	}
 
-	return fsnotify_handle_inode_event(group, inode_mark, mask, data, data_type,
-					   dir, name, cookie);
+	return fsnotify_handle_inode_event(group, inode_mark, mask, event_info);
 }
 
-static int send_to_group(__u32 mask, const void *data, int data_type,
-			 struct inode *dir, const struct qstr *file_name,
-			 u32 cookie, struct fsnotify_iter_info *iter_info)
+static int send_to_group(__u32 mask,
+			 const struct fsnotify_event_info *event_info,
+			 struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_group *group = NULL;
 	__u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS);
@@ -351,18 +358,18 @@ static int send_to_group(__u32 mask, const void *data, int data_type,
 
 	pr_debug("%s: group=%p mask=%x marks_mask=%x marks_ignored_mask=%x data=%p data_type=%d dir=%p cookie=%d\n",
 		 __func__, group, mask, marks_mask, marks_ignored_mask,
-		 data, data_type, dir, cookie);
+		 event_info->data, event_info->data_type, event_info->dir,
+		 event_info->cookie);
 
 	if (!(test_mask & marks_mask & ~marks_ignored_mask))
 		return 0;
 
 	if (group->ops->handle_event) {
-		return group->ops->handle_event(group, mask, data, data_type, dir,
-						file_name, cookie, iter_info);
+		return group->ops->handle_event(group, mask, event_info,
+						iter_info);
 	}
 
-	return fsnotify_handle_event(group, mask, data, data_type, dir,
-				     file_name, cookie, iter_info);
+	return fsnotify_handle_event(group, mask, event_info, iter_info);
 }
 
 static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp)
@@ -448,21 +455,22 @@ static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
  * in whatever means they feel necessary.
  *
  * @mask:	event type and flags
+ * Input args in struct fsnotify_event_info:
  * @data:	object that event happened on
  * @data_type:	type of object for fanotify_data_XXX() accessors
  * @dir:	optional directory associated with event -
- *		if @file_name is not NULL, this is the directory that
- *		@file_name is relative to
- * @file_name:	optional file name associated with event
+ *		if @name is not NULL, this is the directory that
+ *		@name is relative to
+ * @name:	optional file name associated with event
  * @inode:	optional inode associated with event -
  *		either @dir or @inode must be non-NULL.
  *		if both are non-NULL event may be reported to both.
  * @cookie:	inotify rename cookie
  */
-int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
-	     const struct qstr *file_name, struct inode *inode, u32 cookie)
+int __fsnotify(__u32 mask, const struct fsnotify_event_info *event_info)
 {
-	const struct path *path = fsnotify_data_path(data, data_type);
+	const struct path *path = fsnotify_event_info_path(event_info);
+	struct inode *inode = event_info->inode;
 	struct fsnotify_iter_info iter_info = {};
 	struct super_block *sb;
 	struct mount *mnt = NULL;
@@ -475,13 +483,13 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
 
 	if (!inode) {
 		/* Dirent event - report on TYPE_INODE to dir */
-		inode = dir;
+		inode = event_info->dir;
 	} else if (mask & FS_EVENT_ON_CHILD) {
 		/*
 		 * Event on child - report on TYPE_PARENT to dir if it is
 		 * watching children and on TYPE_INODE to child.
 		 */
-		parent = dir;
+		parent = event_info->dir;
 	}
 	sb = inode->i_sb;
 
@@ -538,8 +546,7 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
 	 * That's why this traversal is so complicated...
 	 */
 	while (fsnotify_iter_select_report_types(&iter_info)) {
-		ret = send_to_group(mask, data, data_type, dir, file_name,
-				    cookie, &iter_info);
+		ret = send_to_group(mask, event_info, &iter_info);
 
 		if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
 			goto out;
@@ -552,7 +559,7 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(fsnotify);
+EXPORT_SYMBOL_GPL(__fsnotify);
 
 static __init int fsnotify_init(void)
 {
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index f8acddcf54fb..8c2c681b4495 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -30,7 +30,10 @@ static inline void fsnotify_name(struct inode *dir, __u32 mask,
 				 struct inode *child,
 				 const struct qstr *name, u32 cookie)
 {
-	fsnotify(mask, child, FSNOTIFY_EVENT_INODE, dir, name, NULL, cookie);
+	__fsnotify(mask, &(struct fsnotify_event_info) {
+			.data = child, .data_type = FSNOTIFY_EVENT_INODE,
+			.dir = dir, .name = name, .cookie = cookie,
+			});
 }
 
 static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
@@ -44,7 +47,10 @@ static inline void fsnotify_inode(struct inode *inode, __u32 mask)
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_ISDIR;
 
-	fsnotify(mask, inode, FSNOTIFY_EVENT_INODE, NULL, NULL, inode, 0);
+	__fsnotify(mask, &(struct fsnotify_event_info) {
+			.data = inode, .data_type = FSNOTIFY_EVENT_INODE,
+			.inode = inode,
+			});
 }
 
 /* Notify this dentry's parent about a child's events. */
@@ -68,7 +74,10 @@ static inline int fsnotify_parent(struct dentry *dentry, __u32 mask,
 	return __fsnotify_parent(dentry, mask, data, data_type);
 
 notify_child:
-	return fsnotify(mask, data, data_type, NULL, NULL, inode, 0);
+	return __fsnotify(mask, &(struct fsnotify_event_info) {
+				.data = data, .data_type = data_type,
+				.inode = inode,
+				});
 }
 
 /*
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index f9e2c6cd0f7d..b1590f654ade 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -112,6 +112,28 @@ struct fsnotify_iter_info;
 
 struct mem_cgroup;
 
+/*
+ * Event info args passed to fsnotify() and to backends on handle_event():
+ * @data:	object that event happened on
+ * @data_type:	type of object for fanotify_data_XXX() accessors
+ * @dir:	optional directory associated with event -
+ *		if @name is not NULL, this is the directory that
+ *		@name is relative to
+ * @name:	optional file name associated with event
+ * @inode:	optional inode associated with event -
+ *		either @dir or @inode must be non-NULL.
+ *		if both are non-NULL event may be reported to both.
+ * @cookie:	inotify rename cookie
+ */
+struct fsnotify_event_info {
+	const void *data;
+	int data_type;
+	struct inode *dir;
+	const struct qstr *name;
+	struct inode *inode;
+	u32 cookie;
+};
+
 /*
  * Each group much define these ops.  The fsnotify infrastructure will call
  * these operations for each relevant group.
@@ -119,13 +141,7 @@ struct mem_cgroup;
  * handle_event - main call for a group to handle an fs event
  * @group:	group to notify
  * @mask:	event type and flags
- * @data:	object that event happened on
- * @data_type:	type of object for fanotify_data_XXX() accessors
- * @dir:	optional directory associated with event -
- *		if @file_name is not NULL, this is the directory that
- *		@file_name is relative to
- * @file_name:	optional file name associated with event
- * @cookie:	inotify rename cookie
+ * @event_info: information attached to the event
  * @iter_info:	array of marks from this group that are interested in the event
  *
  * handle_inode_event - simple variant of handle_event() for groups that only
@@ -147,8 +163,7 @@ struct mem_cgroup;
  */
 struct fsnotify_ops {
 	int (*handle_event)(struct fsnotify_group *group, u32 mask,
-			    const void *data, int data_type, struct inode *dir,
-			    const struct qstr *file_name, u32 cookie,
+			    const struct fsnotify_event_info *event_info,
 			    struct fsnotify_iter_info *iter_info);
 	int (*handle_inode_event)(struct fsnotify_mark *mark, u32 mask,
 			    struct inode *inode, struct inode *dir,
@@ -262,6 +277,12 @@ static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
 	}
 }
 
+static inline struct inode *fsnotify_event_info_inode(
+				const struct fsnotify_event_info *event_info)
+{
+	return fsnotify_data_inode(event_info->data, event_info->data_type);
+}
+
 static inline const struct path *fsnotify_data_path(const void *data,
 						    int data_type)
 {
@@ -273,6 +294,12 @@ static inline const struct path *fsnotify_data_path(const void *data,
 	}
 }
 
+static inline const struct path *fsnotify_event_info_path(
+				const struct fsnotify_event_info *event_info)
+{
+	return fsnotify_data_path(event_info->data, event_info->data_type);
+}
+
 enum fsnotify_obj_type {
 	FSNOTIFY_OBJ_TYPE_INODE,
 	FSNOTIFY_OBJ_TYPE_PARENT,
@@ -410,11 +437,22 @@ struct fsnotify_mark {
 /* called from the vfs helpers */
 
 /* main fsnotify call to send events */
-extern int fsnotify(__u32 mask, const void *data, int data_type,
-		    struct inode *dir, const struct qstr *name,
-		    struct inode *inode, u32 cookie);
-extern int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
-			   int data_type);
+extern int __fsnotify(__u32 mask,
+		      const struct fsnotify_event_info *event_info);
+extern int __fsnotify_parent(struct dentry *dentry, __u32 mask,
+			     const void *data, int data_type);
+
+static inline int fsnotify(__u32 mask, const void *data, int data_type,
+			   struct inode *dir, const struct qstr *name,
+			   struct inode *inode, u32 cookie)
+{
+	return __fsnotify(mask, &(struct fsnotify_event_info) {
+				.data = data, .data_type = data_type,
+				.dir = dir, .name = name, .inode = inode,
+				.cookie = cookie,
+				});
+}
+
 extern void __fsnotify_inode_delete(struct inode *inode);
 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
 extern void fsnotify_sb_delete(struct super_block *sb);
@@ -594,15 +632,14 @@ static inline void fsnotify_init_event(struct fsnotify_event *event)
 
 #else
 
-static inline int fsnotify(__u32 mask, const void *data, int data_type,
-			   struct inode *dir, const struct qstr *name,
-			   struct inode *inode, u32 cookie)
+static inline int fsnotify(__u32 mask,
+			   const struct fsnotify_event_info *event_info)
 {
 	return 0;
 }
 
 static inline int __fsnotify_parent(struct dentry *dentry, __u32 mask,
-				  const void *data, int data_type)
+				    const void *data, int data_type)
 {
 	return 0;
 }
-- 
2.32.0