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Commit 3bdba28b authored by Al Viro's avatar Al Viro
Browse files

namei: lift link_path_walk() call out of trailing_symlink() 



Make trailing_symlink() return the pathname to traverse or ERR_PTR(-E...).
A subtle point is that for "magic" symlinks it returns "" now - that
leads to link_path_walk("", nd), which is immediately returning 0 and
we are back to the treatment of the last component, at whereever the
damn thing has left us.

Reduces the stack footprint - link_path_walk() called on more shallow
stack now.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 368ee9ba

fs/namei.c

+23 −27
Original line number Diff line number Diff line
@@ -1970,24 +1970,24 @@ static void path_cleanup(struct nameidata *nd) 
	}

}



static int trailing_symlink(struct nameidata *nd)

static const char *trailing_symlink(struct nameidata *nd)

{

	const char *s;

	int error = may_follow_link(nd);

	if (unlikely(error)) {

		terminate_walk(nd);

		return error;

		return ERR_PTR(error);

	}

	nd->flags |= LOOKUP_PARENT;

	nd->stack[0].name = NULL;

	s = get_link(nd);

	if (unlikely(IS_ERR(s))) {

		terminate_walk(nd);

		return PTR_ERR(s);

		return s;

	}

	if (unlikely(!s))

		return 0;

	return link_path_walk(s, nd);

		s = "";

	return s;

}



static inline int lookup_last(struct nameidata *nd)
@@ -2017,11 +2017,11 @@ static int path_lookupat(int dfd, const struct filename *name, 


	if (IS_ERR(s))

		return PTR_ERR(s);

	err = link_path_walk(s, nd);

	if (!err) {

		while ((err = lookup_last(nd)) > 0) {

			err = trailing_symlink(nd);

			if (err)

	while (!(err = link_path_walk(s, nd))

		&& ((err = lookup_last(nd)) > 0)) {

		s = trailing_symlink(nd);

		if (IS_ERR(s)) {

			err = PTR_ERR(s);

			break;

		}

	}
@@ -2401,16 +2401,14 @@ path_mountpoint(int dfd, const struct filename *name, struct path *path, 
	int err;

	if (IS_ERR(s))

		return PTR_ERR(s);

	err = link_path_walk(s, nd);

	if (unlikely(err))

		goto out;



	while ((err = mountpoint_last(nd, path)) > 0) {

		err = trailing_symlink(nd);

		if (err)

	while (!(err = link_path_walk(s, nd)) &&

		(err = mountpoint_last(nd, path)) > 0) {

		s = trailing_symlink(nd);

		if (IS_ERR(s)) {

			err = PTR_ERR(s);

			break;

		}

out:

	}

	path_cleanup(nd);

	return err;

}
@@ -3282,17 +3280,15 @@ static struct file *path_openat(int dfd, struct filename *pathname, 
		put_filp(file);

		return ERR_CAST(s);

	}

	error = link_path_walk(s, nd);

	if (unlikely(error))

		goto out;



	while ((error = do_last(nd, file, op, &opened, pathname)) > 0) {

	while (!(error = link_path_walk(s, nd)) &&

		(error = do_last(nd, file, op, &opened, pathname)) > 0) {

		nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);

		error = trailing_symlink(nd);

		if (unlikely(error))

		s = trailing_symlink(nd);

		if (IS_ERR(s)) {

			error = PTR_ERR(s);

			break;

		}

out:

	}

	path_cleanup(nd);

out2:

	if (!(opened & FILE_OPENED)) {