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Commit 697f514d authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
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vfs: split do_lookup() 



Split do_lookup() into two functions:

  lookup_fast() - does cached lookup without i_mutex
  lookup_slow() - does lookup with i_mutex

Both follow managed dentries.

The new functions are needed by atomic_open.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e41f941a

fs/namei.c

+45 −14
Original line number Diff line number Diff line
@@ -1125,7 +1125,7 @@ static struct dentry *__lookup_hash(struct qstr *name, 
 *  small and for now I'd prefer to have fast path as straight as possible.

 *  It _is_ time-critical.

 */

static int do_lookup(struct nameidata *nd, struct qstr *name,

static int lookup_fast(struct nameidata *nd, struct qstr *name,

		       struct path *path, struct inode **inode)

{

	struct vfsmount *mnt = nd->path.mnt;
@@ -1208,7 +1208,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, 
			goto need_lookup;

		}

	}

done:



	path->mnt = mnt;

	path->dentry = dentry;

	err = follow_managed(path, nd->flags);
@@ -1222,6 +1222,17 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, 
	return 0;



need_lookup:

	return 1;

}



/* Fast lookup failed, do it the slow way */

static int lookup_slow(struct nameidata *nd, struct qstr *name,

		       struct path *path)

{

	struct dentry *dentry, *parent;

	int err;



	parent = nd->path.dentry;

	BUG_ON(nd->inode != parent->d_inode);



	mutex_lock(&parent->d_inode->i_mutex);
@@ -1229,7 +1240,16 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, 
	mutex_unlock(&parent->d_inode->i_mutex);

	if (IS_ERR(dentry))

		return PTR_ERR(dentry);

	goto done;

	path->mnt = nd->path.mnt;

	path->dentry = dentry;

	err = follow_managed(path, nd->flags);

	if (unlikely(err < 0)) {

		path_put_conditional(path, nd);

		return err;

	}

	if (err)

		nd->flags |= LOOKUP_JUMPED;

	return 0;

}



static inline int may_lookup(struct nameidata *nd)
@@ -1301,21 +1321,26 @@ static inline int walk_component(struct nameidata *nd, struct path *path, 
	 */

	if (unlikely(type != LAST_NORM))

		return handle_dots(nd, type);

	err = do_lookup(nd, name, path, &inode);

	err = lookup_fast(nd, name, path, &inode);

	if (unlikely(err)) {

		terminate_walk(nd);

		return err;

	}

	if (!inode) {

		path_to_nameidata(path, nd);

		terminate_walk(nd);

		return -ENOENT;

		if (err < 0)

			goto out_err;



		err = lookup_slow(nd, name, path);

		if (err < 0)

			goto out_err;



		inode = path->dentry->d_inode;

	}

	err = -ENOENT;

	if (!inode)

		goto out_path_put;



	if (should_follow_link(inode, follow)) {

		if (nd->flags & LOOKUP_RCU) {

			if (unlikely(unlazy_walk(nd, path->dentry))) {

				terminate_walk(nd);

				return -ECHILD;

				err = -ECHILD;

				goto out_err;

			}

		}

		BUG_ON(inode != path->dentry->d_inode);
@@ -1324,6 +1349,12 @@ static inline int walk_component(struct nameidata *nd, struct path *path, 
	path_to_nameidata(path, nd);

	nd->inode = inode;

	return 0;



out_path_put:

	path_to_nameidata(path, nd);

out_err:

	terminate_walk(nd);

	return err;

}



/*