Commit def4af30 authored by Al Viro's avatar Al Viro
Browse files

Get rid of symlink body copying 



Now that nd->last stays around until ->put_link() is called, we can
just postpone that ->put_link() in do_filp_open() a bit and don't
bother with copying.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3866248e

fs/namei.c

+24 −31
Original line number Diff line number Diff line
@@ -498,8 +498,6 @@ static int link_path_walk(const char *, struct nameidata *); 


static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)

{

	int res = 0;

	char *name;

	if (IS_ERR(link))

		goto fail;
@@ -510,22 +508,7 @@ static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *l 
		path_get(&nd->root);

	}



	res = link_path_walk(link, nd);

	if (nd->depth || res || nd->last_type!=LAST_NORM)

		return res;

	/*

	 * If it is an iterative symlinks resolution in open_namei() we

	 * have to copy the last component. And all that crap because of

	 * bloody create() on broken symlinks. Furrfu...

	 */

	name = __getname();

	if (unlikely(!name)) {

		path_put(&nd->path);

		return -ENOMEM;

	}

	strcpy(name, nd->last.name);

	nd->last.name = name;

	return 0;

	return link_path_walk(link, nd);

fail:

	path_put(&nd->path);

	return PTR_ERR(link);
@@ -547,10 +530,10 @@ static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 
	nd->path.dentry = path->dentry;

}



static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)

static __always_inline int

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

{

	int error;

	void *cookie;

	struct dentry *dentry = path->dentry;



	touch_atime(path->mnt, dentry);
@@ -562,9 +545,9 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata 
	}

	mntget(path->mnt);

	nd->last_type = LAST_BIND;

	cookie = dentry->d_inode->i_op->follow_link(dentry, nd);

	error = PTR_ERR(cookie);

	if (!IS_ERR(cookie)) {

	*p = dentry->d_inode->i_op->follow_link(dentry, nd);

	error = PTR_ERR(*p);

	if (!IS_ERR(*p)) {

		char *s = nd_get_link(nd);

		error = 0;

		if (s)
@@ -574,8 +557,6 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata 
			if (error)

				path_put(&nd->path);

		}

		if (dentry->d_inode->i_op->put_link)

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

	}

	return error;

}
@@ -589,6 +570,7 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata 
 */

static inline int do_follow_link(struct path *path, struct nameidata *nd)

{

	void *cookie;

	int err = -ELOOP;

	if (current->link_count >= MAX_NESTED_LINKS)

		goto loop;
@@ -602,7 +584,9 @@ static inline int do_follow_link(struct path *path, struct nameidata *nd) 
	current->link_count++;

	current->total_link_count++;

	nd->depth++;

	err = __do_follow_link(path, nd);

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

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

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

	path_put(path);

	current->link_count--;

	nd->depth--;
@@ -1847,6 +1831,9 @@ reval: 
		nd.flags |= LOOKUP_EXCL;

	filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);

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

		struct path holder;

		struct inode *inode;

		void *cookie;

		error = -ELOOP;

		if ((open_flag & O_NOFOLLOW) || count++ == 32)

			goto exit_dput;
@@ -1865,18 +1852,24 @@ reval: 
		error = security_inode_follow_link(path.dentry, &nd);

		if (error)

			goto exit_dput;

		error = __do_follow_link(&path, &nd);

		path_put(&path);

		if (error) {

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

		if (unlikely(error)) {

			/* nd.path had been dropped */

			inode = path.dentry->d_inode;

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

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

			path_put(&path);

			release_open_intent(&nd);

			filp = ERR_PTR(error);

			goto out;

		}

		holder = path;

		nd.flags &= ~LOOKUP_PARENT;

		filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);

		if (nd.last_type == LAST_NORM)

			__putname(nd.last.name);

		inode = holder.dentry->d_inode;

		if (inode->i_op->put_link)

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

		path_put(&holder);

	}

out:

	if (nd.root.mnt)