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 <[email protected]>

fs/notify/fanotify/fanotify.c

@@ -17,9 +17,9 @@ static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
 	    old->data_type == new->data_type &&
 	    old->tgid == new->tgid) {
 		switch (old->data_type) {
-		case (FSNOTIFY_EVENT_PATH):
-			if ((old->path.mnt == new->path.mnt) &&
-			    (old->path.dentry == new->path.dentry))
+		case (FSNOTIFY_EVENT_FILE):
+			if ((old->file->f_path.mnt == new->file->f_path.mnt) &&
+			    (old->file->f_path.dentry == new->file->f_path.dentry))
 				return true;
 		case (FSNOTIFY_EVENT_NONE):
 			return true;
@@ -226,7 +226,7 @@ static bool fanotify_should_send_event(struct fsnotify_group *group, struct inod
 		return false;
 
 	/* if we don't have enough info to send an event to userspace say no */
-	if (data_type != FSNOTIFY_EVENT_PATH)
+	if (data_type != FSNOTIFY_EVENT_FILE)
 		return false;
 
 	if (mnt)

fs/notify/fanotify/fanotify_user.c

@@ -65,7 +65,7 @@ static int create_fd(struct fsnotify_group *group, struct fsnotify_event *event)
 	if (client_fd < 0)
 		return client_fd;
 
-	if (event->data_type != FSNOTIFY_EVENT_PATH) {
+	if (event->data_type != FSNOTIFY_EVENT_FILE) {
 		WARN_ON(1);
 		put_unused_fd(client_fd);
 		return -EINVAL;
@@ -75,8 +75,8 @@ static int create_fd(struct fsnotify_group *group, struct fsnotify_event *event)
 	 * we need a new file handle for the userspace program so it can read even if it was
 	 * originally opened O_WRONLY.
 	 */
-	dentry = dget(event->path.dentry);
-	mnt = mntget(event->path.mnt);
+	dentry = dget(event->file->f_path.dentry);
+	mnt = mntget(event->file->f_path.mnt);
 	/* it's possible this event was an overflow event.  in that case dentry and mnt
 	 * are NULL;  That's fine, just don't call dentry open */
 	if (dentry && mnt)

fs/notify/fsnotify.c

@@ -84,15 +84,15 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
 }
 
 /* Notify this dentry's parent about a child's events. */
-void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
+void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask)
 {
 	struct dentry *parent;
 	struct inode *p_inode;
 	bool send = false;
 	bool should_update_children = false;
 
 	if (!dentry)
-		dentry = path->dentry;
+		dentry = file->f_path.dentry;
 
 	if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
 		return;
@@ -124,8 +124,8 @@ void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
 		 * specifies these are events which came from a child. */
 		mask |= FS_EVENT_ON_CHILD;
 
-		if (path)
-			fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
+		if (file)
+			fsnotify(p_inode, mask, file, FSNOTIFY_EVENT_FILE,
 				 dentry->d_name.name, 0);
 		else
 			fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
@@ -154,10 +154,10 @@ void __fsnotify_flush_ignored_mask(struct inode *inode, void *data, int data_is)
 		spin_unlock(&inode->i_lock);
 	}
 
-	if (data_is == FSNOTIFY_EVENT_PATH) {
+	if (data_is == FSNOTIFY_EVENT_FILE) {
 		struct vfsmount *mnt;
 
-		mnt = ((struct path *)data)->mnt;
+		mnt = ((struct file *)data)->f_path.mnt;
 		if (mnt && !hlist_empty(&mnt->mnt_fsnotify_marks)) {
 			spin_lock(&mnt->mnt_root->d_lock);
 			hlist_for_each_entry(mark, node, &mnt->mnt_fsnotify_marks, m.m_list) {
@@ -228,8 +228,8 @@ int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
 	    !(test_mask & fsnotify_vfsmount_mask))
 		return 0;
 
-	if (data_is == FSNOTIFY_EVENT_PATH)
-		mnt = ((struct path *)data)->mnt;
+	if (data_is == FSNOTIFY_EVENT_FILE)
+		mnt = ((struct file *)data)->f_path.mnt;
 
 	/* if this inode's directed listeners don't care and nothing on the vfsmount
 	 * listeners list cares, nothing to do */

fs/notify/inotify/inotify_fsnotify.c

@@ -52,9 +52,9 @@ static bool event_compare(struct fsnotify_event *old, struct fsnotify_event *new
 			    !strcmp(old->file_name, new->file_name))
 				return true;
 			break;
-		case (FSNOTIFY_EVENT_PATH):
-			if ((old->path.mnt == new->path.mnt) &&
-			    (old->path.dentry == new->path.dentry))
+		case (FSNOTIFY_EVENT_FILE):
+			if ((old->file->f_path.mnt == new->file->f_path.mnt) &&
+			    (old->file->f_path.dentry == new->file->f_path.dentry))
 				return true;
 			break;
 		case (FSNOTIFY_EVENT_NONE):
@@ -165,10 +165,10 @@ static bool inotify_should_send_event(struct fsnotify_group *group, struct inode
 	send = (fsn_mark->mask & mask);
 
 	if (send && (fsn_mark->mask & FS_EXCL_UNLINK) &&
-	    (data_type == FSNOTIFY_EVENT_PATH)) {
-		struct path *path  = data;
+	    (data_type == FSNOTIFY_EVENT_FILE)) {
+		struct file *file  = data;
 
-		if (d_unlinked(path->dentry))
+		if (d_unlinked(file->f_path.dentry))
 			send = false;
 	}
 

fs/notify/notification.c

@@ -31,6 +31,7 @@
  * allocated and used.
  */
 
+#include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -89,8 +90,8 @@ void fsnotify_put_event(struct fsnotify_event *event)
 	if (atomic_dec_and_test(&event->refcnt)) {
 		pr_debug("%s: event=%p\n", __func__, event);
 
-		if (event->data_type == FSNOTIFY_EVENT_PATH)
-			path_put(&event->path);
+		if (event->data_type == FSNOTIFY_EVENT_FILE)
+			fput(event->file);
 
 		BUG_ON(!list_empty(&event->private_data_list));
 
@@ -375,8 +376,8 @@ struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event)
 		}
 	}
 	event->tgid = get_pid(old_event->tgid);
-	if (event->data_type == FSNOTIFY_EVENT_PATH)
-		path_get(&event->path);
+	if (event->data_type == FSNOTIFY_EVENT_FILE)
+		get_file(event->file);
 
 	return event;
 }
@@ -423,20 +424,17 @@ struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask,
 	event->data_type = data_type;
 
 	switch (data_type) {
-	case FSNOTIFY_EVENT_PATH: {
-		struct path *path = data;
-		event->path.dentry = path->dentry;
-		event->path.mnt = path->mnt;
-		path_get(&event->path);
+	case FSNOTIFY_EVENT_FILE: {
+		event->file = data;
+		get_file(event->file);
 		break;
 	}
 	case FSNOTIFY_EVENT_INODE:
 		event->inode = data;
 		break;
 	case FSNOTIFY_EVENT_NONE:
 		event->inode = NULL;
-		event->path.dentry = NULL;
-		event->path.mnt = NULL;
+		event->file = NULL;
 		break;
 	default:
 		BUG();

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);
 	}
 }
 

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)

kernel/audit_watch.c

@@ -545,8 +545,8 @@ static int audit_watch_handle_event(struct fsnotify_group *group, struct fsnotif
 		return 0;
 
 	switch (event->data_type) {
-	case (FSNOTIFY_EVENT_PATH):
-		inode = event->path.dentry->d_inode;
+	case (FSNOTIFY_EVENT_FILE):
+		inode = event->file->f_path.dentry->d_inode;
 		break;
 	case (FSNOTIFY_EVENT_INODE):
 		inode = event->inode;