Fix f_flags/f_mode in case of lookup_instantiate_filp() from open(pathname, 3)

Just set f_flags when shoving struct file into nameidata; don't
postpone that until __dentry_open().  do_filp_open() has correct
value; lookup_instantiate_filp() doesn't - we lose the difference
between O_RDWR and 3 by that point.

We still set .intent.open.flags, so no fs code needs to be changed.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/internal.h

@@ -85,3 +85,10 @@ extern struct file *get_empty_filp(void);
  * super.c
  */
 extern int do_remount_sb(struct super_block *, int, void *, int);
+
+/*
+ * open.c
+ */
+struct nameidata;
+extern struct file *nameidata_to_filp(struct nameidata *);
+extern void release_open_intent(struct nameidata *);

fs/namei.c

@@ -1640,6 +1640,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
 		if (filp == NULL)
 			return ERR_PTR(-ENFILE);
 		nd.intent.open.file = filp;
+		filp->f_flags = open_flag;
 		nd.intent.open.flags = flag;
 		nd.intent.open.create_mode = 0;
 		error = do_path_lookup(dfd, pathname,
@@ -1685,6 +1686,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
 	if (filp == NULL)
 		goto exit_parent;
 	nd.intent.open.file = filp;
+	filp->f_flags = open_flag;
 	nd.intent.open.flags = flag;
 	nd.intent.open.create_mode = mode;
 	dir = nd.path.dentry;
@@ -1725,7 +1727,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
 			mnt_drop_write(nd.path.mnt);
 			goto exit;
 		}
-		filp = nameidata_to_filp(&nd, open_flag);
+		filp = nameidata_to_filp(&nd);
 		mnt_drop_write(nd.path.mnt);
 		if (nd.root.mnt)
 			path_put(&nd.root);
@@ -1789,7 +1791,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
 			mnt_drop_write(nd.path.mnt);
 		goto exit;
 	}
-	filp = nameidata_to_filp(&nd, open_flag);
+	filp = nameidata_to_filp(&nd);
 	if (!IS_ERR(filp)) {
 		error = ima_path_check(&filp->f_path, filp->f_mode &
 			       (MAY_READ | MAY_WRITE | MAY_EXEC));

fs/open.c

@@ -821,15 +821,14 @@ static inline int __get_file_write_access(struct inode *inode,
 }
 
 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
-					int flags, struct file *f,
+					struct file *f,
 					int (*open)(struct inode *, struct file *),
 					const struct cred *cred)
 {
 	struct inode *inode;
 	int error;
 
-	f->f_flags = flags;
-	f->f_mode = (__force fmode_t)((flags+1) & O_ACCMODE) | FMODE_LSEEK |
+	f->f_mode = (__force fmode_t)((f->f_flags+1) & O_ACCMODE) | FMODE_LSEEK |
 				FMODE_PREAD | FMODE_PWRITE;
 	inode = dentry->d_inode;
 	if (f->f_mode & FMODE_WRITE) {
@@ -930,7 +929,6 @@ struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry
 	if (IS_ERR(dentry))
 		goto out_err;
 	nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
-					     nd->intent.open.flags - 1,
 					     nd->intent.open.file,
 					     open, cred);
 out:
@@ -949,7 +947,7 @@ EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
  *
  * Note that this function destroys the original nameidata
  */
-struct file *nameidata_to_filp(struct nameidata *nd, int flags)
+struct file *nameidata_to_filp(struct nameidata *nd)
 {
 	const struct cred *cred = current_cred();
 	struct file *filp;
@@ -958,7 +956,7 @@ struct file *nameidata_to_filp(struct nameidata *nd, int flags)
 	filp = nd->intent.open.file;
 	/* Has the filesystem initialised the file for us? */
 	if (filp->f_path.dentry == NULL)
-		filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
+		filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp,
 				     NULL, cred);
 	else
 		path_put(&nd->path);
@@ -997,7 +995,8 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
 		return ERR_PTR(error);
 	}
 
-	return __dentry_open(dentry, mnt, flags, f, NULL, cred);
+	f->f_flags = flags;
+	return __dentry_open(dentry, mnt, f, NULL, cred);
 }
 EXPORT_SYMBOL(dentry_open);
 

include/linux/namei.h

@@ -72,8 +72,6 @@ extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
 
 extern struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
 		int (*open)(struct inode *, struct file *));
-extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);
-extern void release_open_intent(struct nameidata *);
 
 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);