Commit 008673ff authored by Al Viro's avatar Al Viro
Browse files

d_path: prepend_path(): lift the inner loop into a new helper 



... and leave the rename_lock/mount_lock handling in prepend_path()
itself

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 2dac0ad1

fs/d_path.c

+38 −39
Original line number Diff line number Diff line
@@ -68,6 +68,42 @@ static bool prepend_name(struct prepend_buffer *p, const struct qstr *name) 
	return true;

}



static int __prepend_path(const struct dentry *dentry, const struct mount *mnt,

			  const struct path *root, struct prepend_buffer *p)

{

	while (dentry != root->dentry || &mnt->mnt != root->mnt) {

		const struct dentry *parent = READ_ONCE(dentry->d_parent);



		if (dentry == mnt->mnt.mnt_root) {

			struct mount *m = READ_ONCE(mnt->mnt_parent);

			struct mnt_namespace *mnt_ns;



			if (likely(mnt != m)) {

				dentry = READ_ONCE(mnt->mnt_mountpoint);

				mnt = m;

				continue;

			}

			/* Global root */

			mnt_ns = READ_ONCE(mnt->mnt_ns);

			/* open-coded is_mounted() to use local mnt_ns */

			if (!IS_ERR_OR_NULL(mnt_ns) && !is_anon_ns(mnt_ns))

				return 1;	// absolute root

			else

				return 2;	// detached or not attached yet

		}



		if (unlikely(dentry == parent))

			/* Escaped? */

			return 3;



		prefetch(parent);

		if (!prepend_name(p, &dentry->d_name))

			break;

		dentry = parent;

	}

	return 0;

}



/**

 * prepend_path - Prepend path string to a buffer

 * @path: the dentry/vfsmount to report
@@ -89,11 +125,9 @@ static int prepend_path(const struct path *path, 
			const struct path *root,

			struct prepend_buffer *p)

{

	struct dentry *dentry;

	struct mount *mnt;

	int error = 0;

	unsigned seq, m_seq = 0;

	struct prepend_buffer b;

	int error;



	rcu_read_lock();

restart_mnt:
@@ -102,43 +136,8 @@ static int prepend_path(const struct path *path, 
	rcu_read_lock();

restart:

	b = *p;

	error = 0;

	dentry = path->dentry;

	mnt = real_mount(path->mnt);

	read_seqbegin_or_lock(&rename_lock, &seq);

	while (dentry != root->dentry || &mnt->mnt != root->mnt) {

		struct dentry * parent;



		if (dentry == mnt->mnt.mnt_root || IS_ROOT(dentry)) {

			struct mount *parent = READ_ONCE(mnt->mnt_parent);

			struct mnt_namespace *mnt_ns;



			/* Escaped? */

			if (dentry != mnt->mnt.mnt_root) {

				error = 3;

				break;

			}

			/* Global root? */

			if (mnt != parent) {

				dentry = READ_ONCE(mnt->mnt_mountpoint);

				mnt = parent;

				continue;

			}

			mnt_ns = READ_ONCE(mnt->mnt_ns);

			/* open-coded is_mounted() to use local mnt_ns */

			if (!IS_ERR_OR_NULL(mnt_ns) && !is_anon_ns(mnt_ns))

				error = 1;	// absolute root

			else

				error = 2;	// detached or not attached yet

			break;

		}

		parent = dentry->d_parent;

		prefetch(parent);

		if (!prepend_name(&b, &dentry->d_name))

			break;



		dentry = parent;

	}

	error = __prepend_path(path->dentry, real_mount(path->mnt), root, &b);

	if (!(seq & 1))

		rcu_read_unlock();

	if (need_seqretry(&rename_lock, seq)) {