merge handle_reval_dot and nameidata_drop_rcu_last (9f1fafee) · Commits · 戴 / test

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;

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