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Commit 574197e0 authored by Al Viro's avatar Al Viro
Browse files

tidy the trailing symlinks traversal up 



* pull the handling of current->total_link_count into
__do_follow_link()
* put the common "do ->put_link() if needed and path_put() the link"
  stuff into a helper (put_link(nd, link, cookie))
* rename __do_follow_link() to follow_link(), while we are at it

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b356379a

fs/namei.c

+26 −45
Original line number Diff line number Diff line
@@ -737,14 +737,31 @@ static inline void path_to_nameidata(const struct path *path, 
	nd->path.dentry = path->dentry;

}



static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)

{

	struct inode *inode = link->dentry->d_inode;

	if (!IS_ERR(cookie) && inode->i_op->put_link)

		inode->i_op->put_link(link->dentry, nd, cookie);

	path_put(link);

}



static __always_inline int

__do_follow_link(const struct path *link, struct nameidata *nd, void **p)

follow_link(struct path *link, struct nameidata *nd, void **p)

{

	int error;

	struct dentry *dentry = link->dentry;



	BUG_ON(nd->flags & LOOKUP_RCU);



	if (unlikely(current->total_link_count >= 40)) {

		*p = ERR_PTR(-ELOOP); /* no ->put_link(), please */

		path_put_conditional(link, nd);

		path_put(&nd->path);

		return -ELOOP;

	}

	cond_resched();

	current->total_link_count++;



	touch_atime(link->mnt, dentry);

	nd_set_link(nd, NULL);
@@ -1356,21 +1373,12 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd) 
	do {

		struct path link = *path;

		void *cookie;

		if (unlikely(current->total_link_count >= 40)) {

			path_put_conditional(path, nd);

			path_put(&nd->path);

			res = -ELOOP;

			break;

		}

		cond_resched();

		current->total_link_count++;

		res = __do_follow_link(&link, nd, &cookie);



		res = follow_link(&link, nd, &cookie);

		if (!res)

			res = walk_component(nd, path, &nd->last,

					     nd->last_type, LOOKUP_FOLLOW);

		if (!IS_ERR(cookie) && link.dentry->d_inode->i_op->put_link)

			link.dentry->d_inode->i_op->put_link(link.dentry, nd, cookie);

		path_put(&link);

		put_link(nd, &link, cookie);

	} while (res > 0);



	current->link_count--;
@@ -1619,27 +1627,15 @@ static int path_lookupat(int dfd, const char *name, 
	err = link_path_walk(name, nd);



	if (!err && !(flags & LOOKUP_PARENT)) {

		int count = 0;

		err = lookup_last(nd, &path);

		while (err > 0) {

			void *cookie;

			struct path link = path;

			struct inode *inode = link.dentry->d_inode;



			if (count++ > 32) {

				path_put_conditional(&path, nd);

				path_put(&nd->path);

				err = -ELOOP;

				break;

			}

			cond_resched();

			nd->flags |= LOOKUP_PARENT;

			err = __do_follow_link(&link, nd, &cookie);

			err = follow_link(&link, nd, &cookie);

			if (!err)

				err = lookup_last(nd, &path);

			if (!IS_ERR(cookie) && inode->i_op->put_link)

				inode->i_op->put_link(link.dentry, nd, cookie);

			path_put(&link);

			put_link(nd, &link, cookie);

		}

	}
@@ -2298,7 +2294,6 @@ static struct file *path_openat(int dfd, const char *pathname, 
	struct file *base = NULL;

	struct file *filp;

	struct path path;

	int count = 0;

	int error;



	filp = get_empty_filp();
@@ -2322,35 +2317,21 @@ static struct file *path_openat(int dfd, const char *pathname, 
	filp = do_last(nd, &path, op, pathname);

	while (unlikely(!filp)) { /* trailing symlink */

		struct path link = path;

		struct inode *linki = link.dentry->d_inode;

		void *cookie;

		if (!(nd->flags & LOOKUP_FOLLOW) || count++ == 32) {

		if (!(nd->flags & LOOKUP_FOLLOW)) {

			path_put_conditional(&path, nd);

			path_put(&nd->path);

			filp = ERR_PTR(-ELOOP);

			break;

		}

		/*

		 * This is subtle. Instead of calling do_follow_link() we do

		 * the thing by hands. The reason is that this way we have zero

		 * link_count and path_walk() (called from ->follow_link)

		 * honoring LOOKUP_PARENT.  After that we have the parent and

		 * last component, i.e. we are in the same situation as after

		 * the first path_walk().  Well, almost - if the last component

		 * is normal we get its copy stored in nd->last.name and we will

		 * have to putname() it when we are done. Procfs-like symlinks

		 * just set LAST_BIND.

		 */

		nd->flags |= LOOKUP_PARENT;

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

		error = __do_follow_link(&link, nd, &cookie);

		error = follow_link(&link, nd, &cookie);

		if (unlikely(error))

			filp = ERR_PTR(error);

		else

			filp = do_last(nd, &path, op, pathname);

		if (!IS_ERR(cookie) && linki->i_op->put_link)

			linki->i_op->put_link(link.dentry, nd, cookie);

		path_put(&link);

		put_link(nd, &link, cookie);

	}

out:

	if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))