From bc3fa141faa10d927d568bb1f958d736c5f6edcd Mon Sep 17 00:00:00 2001
From: jh <jh@FreeBSD.org>
Date: Wed, 9 Jun 2010 15:29:12 +0000
Subject: [PATCH] Add a new function devfs_parent_dirent() for resolving devfs
 parent directory entry. Use the new function in devfs_fqpn(), devfs_lookupx()
 and devfs_vptocnp() instead of manually resolving the parent entry.

Reviewed by:	kib
---
 sys/fs/devfs/devfs.h       |  1 +
 sys/fs/devfs/devfs_devs.c  | 20 ++++++++++++++++++++
 sys/fs/devfs/devfs_vnops.c | 20 +++++++++++---------
 3 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/sys/fs/devfs/devfs.h b/sys/fs/devfs/devfs.h
index 524bec830173..a50a7b066d29 100644
--- a/sys/fs/devfs/devfs.h
+++ b/sys/fs/devfs/devfs.h
@@ -180,6 +180,7 @@ void devfs_populate (struct devfs_mount *dm);
 void devfs_cleanup (struct devfs_mount *dm);
 void devfs_unmount_final(struct devfs_mount *mp);
 struct devfs_dirent *devfs_newdirent (char *name, int namelen);
+struct devfs_dirent *devfs_parent_dirent(struct devfs_dirent *de);
 struct devfs_dirent *devfs_vmkdir (struct devfs_mount *, char *name, int namelen, struct devfs_dirent *dotdot, u_int inode);
 struct devfs_dirent *devfs_find (struct devfs_dirent *dd, const char *name, int namelen);
 
diff --git a/sys/fs/devfs/devfs_devs.c b/sys/fs/devfs/devfs_devs.c
index 4bd672867cca..b14a41fdc5b9 100644
--- a/sys/fs/devfs/devfs_devs.c
+++ b/sys/fs/devfs/devfs_devs.c
@@ -197,6 +197,26 @@ devfs_newdirent(char *name, int namelen)
 	return (de);
 }
 
+struct devfs_dirent *
+devfs_parent_dirent(struct devfs_dirent *de)
+{
+
+	if (de->de_dirent->d_type != DT_DIR)
+		return (de->de_dir);
+
+	if (de->de_flags & (DE_DOT | DE_DOTDOT))
+		return (NULL);
+
+	de = TAILQ_FIRST(&de->de_dlist);	/* "." */
+	if (de == NULL)
+		return (NULL);
+	de = TAILQ_NEXT(de, de_list);		/* ".." */
+	if (de == NULL)
+		return (NULL);
+
+	return (de->de_dir);
+}
+
 struct devfs_dirent *
 devfs_vmkdir(struct devfs_mount *dmp, char *name, int namelen, struct devfs_dirent *dotdot, u_int inode)
 {
diff --git a/sys/fs/devfs/devfs_vnops.c b/sys/fs/devfs/devfs_vnops.c
index 88937a62b2e4..c277355e16e3 100644
--- a/sys/fs/devfs/devfs_vnops.c
+++ b/sys/fs/devfs/devfs_vnops.c
@@ -230,9 +230,11 @@ devfs_vptocnp(struct vop_vptocnp_args *ap)
 		goto finished;
 	}
 	*buflen = i;
-	de = TAILQ_FIRST(&de->de_dlist);	/* "." */
-	de = TAILQ_NEXT(de, de_list);		/* ".." */
-	de = de->de_dir;
+	de = devfs_parent_dirent(de);
+	if (de == NULL) {
+		error = ENOENT;
+		goto finished;
+	}
 	mtx_lock(&devfs_de_interlock);
 	*dvp = de->de_vnode;
 	if (*dvp != NULL) {
@@ -278,9 +280,9 @@ devfs_fqpn(char *buf, struct vnode *dvp, struct componentname *cnp)
 			 return (NULL);
 		bcopy(de->de_dirent->d_name, buf + i,
 		    de->de_dirent->d_namlen);
-		de = TAILQ_FIRST(&de->de_dlist);	/* "." */
-		de = TAILQ_NEXT(de, de_list);		/* ".." */
-		de = de->de_dir;
+		de = devfs_parent_dirent(de);
+		if (de == NULL)
+			return (NULL);
 	}
 	return (buf + i);
 }
@@ -789,10 +791,10 @@ devfs_lookupx(struct vop_lookup_args *ap, int *dm_unlock)
 	if (flags & ISDOTDOT) {
 		if ((flags & ISLASTCN) && nameiop != LOOKUP)
 			return (EINVAL);
+		de = devfs_parent_dirent(dd);
+		if (de == NULL)
+			return (ENOENT);
 		VOP_UNLOCK(dvp, 0);
-		de = TAILQ_FIRST(&dd->de_dlist);	/* "." */
-		de = TAILQ_NEXT(de, de_list);		/* ".." */
-		de = de->de_dir;
 		error = devfs_allocv(de, dvp->v_mount, vpp);
 		*dm_unlock = 0;
 		vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY);