fsnotify: store struct file not struct path

Al explains that calling dentry_open() with a mnt/dentry pair is only
garunteed to be safe if they are already used in an open struct file.  To
make sure this is the case don't store and use a struct path in fsnotify,
always use a struct file.

Signed-off-by: Eric Paris <eparis@redhat.com>

2 files changed, 24 insertions, 29 deletions

diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 59d0df4..e4e2204 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -26,19 +26,18 @@ static inline void fsnotify_d_instantiate(struct dentry *dentry,
 }
 
 /* Notify this dentry's parent about a child's events. */
-static inline void fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
+static inline void fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask)
 {
 	if (!dentry)
-		dentry = path->dentry;
+		dentry = file->f_path.dentry;
 
-	__fsnotify_parent(path, dentry, mask);
+	__fsnotify_parent(file, dentry, mask);
 }
 
 /* simple call site for access decisions */
 static inline int fsnotify_perm(struct file *file, int mask)
 {
-	struct path *path = &file->f_path;
-	struct inode *inode = path->dentry->d_inode;
+	struct inode *inode = file->f_path.dentry->d_inode;
 	__u32 fsnotify_mask = 0;
 
 	if (file->f_mode & FMODE_NONOTIFY)
@@ -52,7 +51,7 @@ static inline int fsnotify_perm(struct file *file, int mask)
 	else
 		BUG();
 
-	return fsnotify(inode, fsnotify_mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+	return fsnotify(inode, fsnotify_mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
 }
 
 /*
@@ -187,16 +186,15 @@ static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)
  */
 static inline void fsnotify_access(struct file *file)
 {
-	struct path *path = &file->f_path;
-	struct inode *inode = path->dentry->d_inode;
+	struct inode *inode = file->f_path.dentry->d_inode;
 	__u32 mask = FS_ACCESS;
 
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_IN_ISDIR;
 
 	if (!(file->f_mode & FMODE_NONOTIFY)) {
-		fsnotify_parent(path, NULL, mask);
-		fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+		fsnotify_parent(file, NULL, mask);
+		fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
 	}
 }
 
@@ -205,16 +203,15 @@ static inline void fsnotify_access(struct file *file)
  */
 static inline void fsnotify_modify(struct file *file)
 {
-	struct path *path = &file->f_path;
-	struct inode *inode = path->dentry->d_inode;
+	struct inode *inode = file->f_path.dentry->d_inode;
 	__u32 mask = FS_MODIFY;
 
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_IN_ISDIR;
 
 	if (!(file->f_mode & FMODE_NONOTIFY)) {
-		fsnotify_parent(path, NULL, mask);
-		fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+		fsnotify_parent(file, NULL, mask);
+		fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
 	}
 }
 
@@ -223,16 +220,15 @@ static inline void fsnotify_modify(struct file *file)
  */
 static inline void fsnotify_open(struct file *file)
 {
-	struct path *path = &file->f_path;
-	struct inode *inode = path->dentry->d_inode;
+	struct inode *inode = file->f_path.dentry->d_inode;
 	__u32 mask = FS_OPEN;
 
 	if (S_ISDIR(inode->i_mode))
 		mask |= FS_IN_ISDIR;
 
 	if (!(file->f_mode & FMODE_NONOTIFY)) {
-		fsnotify_parent(path, NULL, mask);
-		fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+		fsnotify_parent(file, NULL, mask);
+		fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
 	}
 }
 
@@ -241,7 +237,6 @@ static inline void fsnotify_open(struct file *file)
  */
 static inline void fsnotify_close(struct file *file)
 {
-	struct path *path = &file->f_path;
 	struct inode *inode = file->f_path.dentry->d_inode;
 	fmode_t mode = file->f_mode;
 	__u32 mask = (mode & FMODE_WRITE) ? FS_CLOSE_WRITE : FS_CLOSE_NOWRITE;
@@ -250,8 +245,8 @@ static inline void fsnotify_close(struct file *file)
 		mask |= FS_IN_ISDIR;
 
 	if (!(file->f_mode & FMODE_NONOTIFY)) {
-		fsnotify_parent(path, NULL, mask);
-		fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+		fsnotify_parent(file, NULL, mask);
+		fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
 	}
 }
 
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 564b5ea..3410d38 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -223,20 +223,20 @@ struct fsnotify_event {
 	/* to_tell may ONLY be dereferenced during handle_event(). */
 	struct inode *to_tell;	/* either the inode the event happened to or its parent */
 	/*
-	 * depending on the event type we should have either a path or inode
-	 * We hold a reference on path, but NOT on inode.  Since we have the ref on
-	 * the path, it may be dereferenced at any point during this object's
+	 * depending on the event type we should have either a file or inode
+	 * We hold a reference on file, but NOT on inode.  Since we have the ref on
+	 * the file, it may be dereferenced at any point during this object's
 	 * lifetime.  That reference is dropped when this object's refcnt hits
-	 * 0.  If this event contains an inode instead of a path, the inode may
+	 * 0.  If this event contains an inode instead of a file, the inode may
 	 * ONLY be used during handle_event().
 	 */
 	union {
-		struct path path;
+		struct file *file;
 		struct inode *inode;
 	};
 /* when calling fsnotify tell it if the data is a path or inode */
 #define FSNOTIFY_EVENT_NONE	0
-#define FSNOTIFY_EVENT_PATH	1
+#define FSNOTIFY_EVENT_FILE	1
 #define FSNOTIFY_EVENT_INODE	2
 	int data_type;		/* which of the above union we have */
 	atomic_t refcnt;	/* how many groups still are using/need to send this event */
@@ -311,7 +311,7 @@ struct fsnotify_mark {
 /* main fsnotify call to send events */
 extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
 		    const unsigned char *name, u32 cookie);
-extern void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
+extern void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask);
 extern void __fsnotify_inode_delete(struct inode *inode);
 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
 extern u32 fsnotify_get_cookie(void);
@@ -444,7 +444,7 @@ static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int da
 	return 0;
 }
 
-static inline void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
+static inline void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask)
 {}
 
 static inline void __fsnotify_inode_delete(struct inode *inode)