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Commit 9f1fafee authored by Al Viro's avatar Al Viro
Browse files

merge handle_reval_dot and nameidata_drop_rcu_last 



new helper: complete_walk().  Done on successful completion
of walk, drops out of RCU mode, does d_revalidate of final
result if that hadn't been done already.

handle_reval_dot() and nameidata_drop_rcu_last() subsumed into
that one; callers converted to use of complete_walk().

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 19660af7

fs/namei.c

+40 −81
Original line number Diff line number Diff line
@@ -468,43 +468,6 @@ err_root: 
	return -ECHILD;

}



/**

 * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk

 * @nd: nameidata pathwalk data to drop

 * Returns: 0 on success, -ECHILD on failure

 *

 * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk.

 * nd->path should be the final element of the lookup, so nd->root is discarded.

 * Must be called from rcu-walk context.

 */

static int nameidata_drop_rcu_last(struct nameidata *nd)

{

	struct dentry *dentry = nd->path.dentry;



	BUG_ON(!(nd->flags & LOOKUP_RCU));

	nd->flags &= ~LOOKUP_RCU;

	if (!(nd->flags & LOOKUP_ROOT))

		nd->root.mnt = NULL;

	spin_lock(&dentry->d_lock);

	if (!__d_rcu_to_refcount(dentry, nd->seq))

		goto err_unlock;

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

	spin_unlock(&dentry->d_lock);



	mntget(nd->path.mnt);



	rcu_read_unlock();

	br_read_unlock(vfsmount_lock);



	return 0;



err_unlock:

	spin_unlock(&dentry->d_lock);

	rcu_read_unlock();

	br_read_unlock(vfsmount_lock);

	return -ECHILD;

}



/**

 * release_open_intent - free up open intent resources

 * @nd: pointer to nameidata
@@ -548,26 +511,39 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd) 
	return dentry;

}



/*

 * handle_reval_path - force revalidation of a dentry

 *

 * In some situations the path walking code will trust dentries without

 * revalidating them. This causes problems for filesystems that depend on

 * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set

 * (which indicates that it's possible for the dentry to go stale), force

 * a d_revalidate call before proceeding.

/**

 * complete_walk - successful completion of path walk

 * @nd:  pointer nameidata

 *

 * Returns 0 if the revalidation was successful. If the revalidation fails,

 * either return the error returned by d_revalidate or -ESTALE if the

 * revalidation it just returned 0. If d_revalidate returns 0, we attempt to

 * invalidate the dentry. It's up to the caller to handle putting references

 * to the path if necessary.

 * If we had been in RCU mode, drop out of it and legitimize nd->path.

 * Revalidate the final result, unless we'd already done that during

 * the path walk or the filesystem doesn't ask for it.  Return 0 on

 * success, -error on failure.  In case of failure caller does not

 * need to drop nd->path.

 */

static inline int handle_reval_path(struct nameidata *nd)

static int complete_walk(struct nameidata *nd)

{

	struct dentry *dentry = nd->path.dentry;

	int status;



	if (nd->flags & LOOKUP_RCU) {

		nd->flags &= ~LOOKUP_RCU;

		if (!(nd->flags & LOOKUP_ROOT))

			nd->root.mnt = NULL;

		spin_lock(&dentry->d_lock);

		if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {

			spin_unlock(&dentry->d_lock);

			rcu_read_unlock();

			br_read_unlock(vfsmount_lock);

			return -ECHILD;

		}

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

		spin_unlock(&dentry->d_lock);

		mntget(nd->path.mnt);

		rcu_read_unlock();

		br_read_unlock(vfsmount_lock);

	}



	if (likely(!(nd->flags & LOOKUP_JUMPED)))

		return 0;
@@ -585,6 +561,7 @@ static inline int handle_reval_path(struct nameidata *nd) 
	if (!status)

		status = -ESTALE;



	path_put(&nd->path);

	return status;

}
@@ -1598,18 +1575,8 @@ static int path_lookupat(int dfd, const char *name, 
		}

	}



	if (nd->flags & LOOKUP_RCU) {

		/* went all way through without dropping RCU */

		BUG_ON(err);

		if (nameidata_drop_rcu_last(nd))

			err = -ECHILD;

	}



	if (!err) {

		err = handle_reval_path(nd);

		if (err)

			path_put(&nd->path);

	}

	if (!err)

		err = complete_walk(nd);



	if (!err && nd->flags & LOOKUP_DIRECTORY) {

		if (!nd->inode->i_op->lookup) {
@@ -2075,13 +2042,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path, 
			return ERR_PTR(error);

		/* fallthrough */

	case LAST_ROOT:

		if (nd->flags & LOOKUP_RCU) {

			if (nameidata_drop_rcu_last(nd))

				return ERR_PTR(-ECHILD);

		}

		error = handle_reval_path(nd);

		error = complete_walk(nd);

		if (error)

			goto exit;

			return ERR_PTR(error);

		audit_inode(pathname, nd->path.dentry);

		if (open_flag & O_CREAT) {

			error = -EISDIR;
@@ -2089,10 +2052,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path, 
		}

		goto ok;

	case LAST_BIND:

		/* can't be RCU mode here */

		error = handle_reval_path(nd);

		error = complete_walk(nd);

		if (error)

			goto exit;

			return ERR_PTR(error);

		audit_inode(pathname, dir);

		goto ok;

	}
@@ -2111,10 +2073,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path, 
		if (error) /* symlink */

			return NULL;

		/* sayonara */

		if (nd->flags & LOOKUP_RCU) {

			if (nameidata_drop_rcu_last(nd))

		error = complete_walk(nd);

		if (error)

			return ERR_PTR(-ECHILD);

		}



		error = -ENOTDIR;

		if (nd->flags & LOOKUP_DIRECTORY) {
@@ -2126,11 +2087,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path, 
	}



	/* create side of things */



	if (nd->flags & LOOKUP_RCU) {

		if (nameidata_drop_rcu_last(nd))

			return ERR_PTR(-ECHILD);

	}

	error = complete_walk(nd);

	if (error)

		return ERR_PTR(error);



	audit_inode(pathname, dir);

	error = -EISDIR;