now we can fold open_check_o_direct() into do_dentry_open()

These checks are better off in do_dentry_open(); the reason we couldn't
put them there used to be that callers couldn't tell what kind of cleanup
would do_dentry_open() failure call for.  Now that we have FMODE_OPENED,
cleanup is the same in all cases - it's simply fput().  So let's fold
that into do_dentry_open(), as Christoph's patch tried to.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/internal.h

@@ -125,7 +125,6 @@ int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
 int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
 		int flag);
 
-extern int open_check_o_direct(struct file *f);
 extern int vfs_open(const struct path *, struct file *);
 
 /*

fs/namei.c

@@ -3401,8 +3401,6 @@ static int do_last(struct nameidata *nd,
 		goto out;
 	*opened |= FILE_OPENED;
 opened:
-	error = open_check_o_direct(file);
-	if (!error)
 	error = ima_file_check(file, op->acc_mode, *opened);
 	if (!error && will_truncate)
 		error = handle_truncate(file);
@@ -3479,9 +3477,6 @@ static int do_tmpfile(struct nameidata *nd, unsigned flags,
 		goto out2;
 	file->f_path.mnt = path.mnt;
 	error = finish_open(file, child, NULL, opened);
-	if (error)
-		goto out2;
-	error = open_check_o_direct(file);
 out2:
 	mnt_drop_write(path.mnt);
 out:

fs/open.c

@@ -724,16 +724,6 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 	return ksys_fchown(fd, user, group);
 }
 
-int open_check_o_direct(struct file *f)
-{
-	/* NB: we're sure to have correct a_ops only after f_op->open */
-	if (f->f_flags & O_DIRECT) {
-		if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
-			return -EINVAL;
-	}
-	return 0;
-}
-
 static int do_dentry_open(struct file *f,
 			  struct inode *inode,
 			  int (*open)(struct inode *, struct file *))
@@ -808,6 +798,11 @@ static int do_dentry_open(struct file *f,
 
 	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 
+	/* NB: we're sure to have correct a_ops only after f_op->open */
+	if (f->f_flags & O_DIRECT) {
+		if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
+			return -EINVAL;
+	}
 	return 0;
 
 cleanup_all:
@@ -921,8 +916,6 @@ struct file *dentry_open(const struct path *path, int flags,
 	f = alloc_empty_file(flags, cred);
 	if (!IS_ERR(f)) {
 		error = vfs_open(path, f);
-		if (!error)
-			error = open_check_o_direct(f);
 		if (error) {
 			fput(f);
 			f = ERR_PTR(error);