1 files changed, 86 insertions, 67 deletions

diff --git a/fs/namei.c b/fs/namei.c
index dd78f01..a7f7f44 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -493,12 +493,21 @@ fail:
 	return PTR_ERR(link);
 }
 
-static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
+struct path {
+	struct vfsmount *mnt;
+	struct dentry *dentry;
+};
+
+static inline int __do_follow_link(struct path *path, struct nameidata *nd)
 {
 	int error;
+	struct dentry *dentry = path->dentry;
 
-	touch_atime(nd->mnt, dentry);
+	touch_atime(path->mnt, dentry);
 	nd_set_link(nd, NULL);
+
+	if (path->mnt == nd->mnt)
+		mntget(path->mnt);
 	error = dentry->d_inode->i_op->follow_link(dentry, nd);
 	if (!error) {
 		char *s = nd_get_link(nd);
@@ -507,6 +516,8 @@ static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
 		if (dentry->d_inode->i_op->put_link)
 			dentry->d_inode->i_op->put_link(dentry, nd);
 	}
+	dput(dentry);
+	mntput(path->mnt);
 
 	return error;
 }
@@ -518,7 +529,7 @@ static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
  * Without that kind of total limit, nasty chains of consecutive
  * symlinks can cause almost arbitrarily long lookups. 
  */
-static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd)
+static inline int do_follow_link(struct path *path, struct nameidata *nd)
 {
 	int err = -ELOOP;
 	if (current->link_count >= MAX_NESTED_LINKS)
@@ -527,17 +538,20 @@ static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd)
 		goto loop;
 	BUG_ON(nd->depth >= MAX_NESTED_LINKS);
 	cond_resched();
-	err = security_inode_follow_link(dentry, nd);
+	err = security_inode_follow_link(path->dentry, nd);
 	if (err)
 		goto loop;
 	current->link_count++;
 	current->total_link_count++;
 	nd->depth++;
-	err = __do_follow_link(dentry, nd);
+	err = __do_follow_link(path, nd);
 	current->link_count--;
 	nd->depth--;
 	return err;
 loop:
+	dput(path->dentry);
+	if (path->mnt != nd->mnt)
+		mntput(path->mnt);
 	path_release(nd);
 	return err;
 }
@@ -565,87 +579,91 @@ int follow_up(struct vfsmount **mnt, struct dentry **dentry)
 /* no need for dcache_lock, as serialization is taken care in
  * namespace.c
  */
-static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
+static int __follow_mount(struct path *path)
 {
 	int res = 0;
+	while (d_mountpoint(path->dentry)) {
+		struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
+		if (!mounted)
+			break;
+		dput(path->dentry);
+		if (res)
+			mntput(path->mnt);
+		path->mnt = mounted;
+		path->dentry = dget(mounted->mnt_root);
+		res = 1;
+	}
+	return res;
+}
+
+static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
+{
 	while (d_mountpoint(*dentry)) {
 		struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
 		if (!mounted)
 			break;
+		dput(*dentry);
 		mntput(*mnt);
 		*mnt = mounted;
-		dput(*dentry);
 		*dentry = dget(mounted->mnt_root);
-		res = 1;
 	}
-	return res;
 }
 
 /* no need for dcache_lock, as serialization is taken care in
  * namespace.c
  */
-static inline int __follow_down(struct vfsmount **mnt, struct dentry **dentry)
+int follow_down(struct vfsmount **mnt, struct dentry **dentry)
 {
 	struct vfsmount *mounted;
 
 	mounted = lookup_mnt(*mnt, *dentry);
 	if (mounted) {
+		dput(*dentry);
 		mntput(*mnt);
 		*mnt = mounted;
-		dput(*dentry);
 		*dentry = dget(mounted->mnt_root);
 		return 1;
 	}
 	return 0;
 }
 
-int follow_down(struct vfsmount **mnt, struct dentry **dentry)
-{
-	return __follow_down(mnt,dentry);
-}
- 
-static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)
+static inline void follow_dotdot(struct nameidata *nd)
 {
 	while(1) {
 		struct vfsmount *parent;
-		struct dentry *old = *dentry;
+		struct dentry *old = nd->dentry;
 
                 read_lock(&current->fs->lock);
-		if (*dentry == current->fs->root &&
-		    *mnt == current->fs->rootmnt) {
+		if (nd->dentry == current->fs->root &&
+		    nd->mnt == current->fs->rootmnt) {
                         read_unlock(&current->fs->lock);
 			break;
 		}
                 read_unlock(&current->fs->lock);
 		spin_lock(&dcache_lock);
-		if (*dentry != (*mnt)->mnt_root) {
-			*dentry = dget((*dentry)->d_parent);
+		if (nd->dentry != nd->mnt->mnt_root) {
+			nd->dentry = dget(nd->dentry->d_parent);
 			spin_unlock(&dcache_lock);
 			dput(old);
 			break;
 		}
 		spin_unlock(&dcache_lock);
 		spin_lock(&vfsmount_lock);
-		parent = (*mnt)->mnt_parent;
-		if (parent == *mnt) {
+		parent = nd->mnt->mnt_parent;
+		if (parent == nd->mnt) {
 			spin_unlock(&vfsmount_lock);
 			break;
 		}
 		mntget(parent);
-		*dentry = dget((*mnt)->mnt_mountpoint);
+		nd->dentry = dget(nd->mnt->mnt_mountpoint);
 		spin_unlock(&vfsmount_lock);
 		dput(old);
-		mntput(*mnt);
-		*mnt = parent;
+		mntput(nd->mnt);
+		nd->mnt = parent;
 	}
-	follow_mount(mnt, dentry);
+	follow_mount(&nd->mnt, &nd->dentry);
 }
 
-struct path {
-	struct vfsmount *mnt;
-	struct dentry *dentry;
-};
-
 /*
  *  It's more convoluted than I'd like it to be, but... it's still fairly
  *  small and for now I'd prefer to have fast path as straight as possible.
@@ -664,6 +682,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
 done:
 	path->mnt = mnt;
 	path->dentry = dentry;
+	__follow_mount(path);
 	return 0;
 
 need_lookup:
@@ -751,7 +770,7 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
 			case 2:	
 				if (this.name[1] != '.')
 					break;
-				follow_dotdot(&nd->mnt, &nd->dentry);
+				follow_dotdot(nd);
 				inode = nd->dentry->d_inode;
 				/* fallthrough */
 			case 1:
@@ -771,8 +790,6 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
 		err = do_lookup(nd, &this, &next);
 		if (err)
 			break;
-		/* Check mountpoints.. */
-		follow_mount(&next.mnt, &next.dentry);
 
 		err = -ENOENT;
 		inode = next.dentry->d_inode;
@@ -783,10 +800,7 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
 			goto out_dput;
 
 		if (inode->i_op->follow_link) {
-			mntget(next.mnt);
-			err = do_follow_link(next.dentry, nd);
-			dput(next.dentry);
-			mntput(next.mnt);
+			err = do_follow_link(&next, nd);
 			if (err)
 				goto return_err;
 			err = -ENOENT;
@@ -798,6 +812,8 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
 				break;
 		} else {
 			dput(nd->dentry);
+			if (nd->mnt != next.mnt)
+				mntput(nd->mnt);
 			nd->mnt = next.mnt;
 			nd->dentry = next.dentry;
 		}
@@ -819,7 +835,7 @@ last_component:
 			case 2:	
 				if (this.name[1] != '.')
 					break;
-				follow_dotdot(&nd->mnt, &nd->dentry);
+				follow_dotdot(nd);
 				inode = nd->dentry->d_inode;
 				/* fallthrough */
 			case 1:
@@ -833,19 +849,17 @@ last_component:
 		err = do_lookup(nd, &this, &next);
 		if (err)
 			break;
-		follow_mount(&next.mnt, &next.dentry);
 		inode = next.dentry->d_inode;
 		if ((lookup_flags & LOOKUP_FOLLOW)
 		    && inode && inode->i_op && inode->i_op->follow_link) {
-			mntget(next.mnt);
-			err = do_follow_link(next.dentry, nd);
-			dput(next.dentry);
-			mntput(next.mnt);
+			err = do_follow_link(&next, nd);
 			if (err)
 				goto return_err;
 			inode = nd->dentry->d_inode;
 		} else {
 			dput(nd->dentry);
+			if (nd->mnt != next.mnt)
+				mntput(nd->mnt);
 			nd->mnt = next.mnt;
 			nd->dentry = next.dentry;
 		}
@@ -885,6 +899,8 @@ return_base:
 		return 0;
 out_dput:
 		dput(next.dentry);
+		if (nd->mnt != next.mnt)
+			mntput(next.mnt);
 		break;
 	}
 	path_release(nd);
@@ -1398,7 +1414,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
 int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
 {
 	int acc_mode, error = 0;
-	struct dentry *dentry;
+	struct path path;
 	struct dentry *dir;
 	int count = 0;
 
@@ -1442,23 +1458,24 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
 	dir = nd->dentry;
 	nd->flags &= ~LOOKUP_PARENT;
 	down(&dir->d_inode->i_sem);
-	dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+	path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+	path.mnt = nd->mnt;
 
 do_last:
-	error = PTR_ERR(dentry);
-	if (IS_ERR(dentry)) {
+	error = PTR_ERR(path.dentry);
+	if (IS_ERR(path.dentry)) {
 		up(&dir->d_inode->i_sem);
 		goto exit;
 	}
 
 	/* Negative dentry, just create the file */
-	if (!dentry->d_inode) {
+	if (!path.dentry->d_inode) {
 		if (!IS_POSIXACL(dir->d_inode))
 			mode &= ~current->fs->umask;
-		error = vfs_create(dir->d_inode, dentry, mode, nd);
+		error = vfs_create(dir->d_inode, path.dentry, mode, nd);
 		up(&dir->d_inode->i_sem);
 		dput(nd->dentry);
-		nd->dentry = dentry;
+		nd->dentry = path.dentry;
 		if (error)
 			goto exit;
 		/* Don't check for write permission, don't truncate */
@@ -1476,22 +1493,24 @@ do_last:
 	if (flag & O_EXCL)
 		goto exit_dput;
 
-	if (d_mountpoint(dentry)) {
+	if (__follow_mount(&path)) {
 		error = -ELOOP;
 		if (flag & O_NOFOLLOW)
 			goto exit_dput;
-		while (__follow_down(&nd->mnt,&dentry) && d_mountpoint(dentry));
 	}
 	error = -ENOENT;
-	if (!dentry->d_inode)
+	if (!path.dentry->d_inode)
 		goto exit_dput;
-	if (dentry->d_inode->i_op && dentry->d_inode->i_op->follow_link)
+	if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
 		goto do_link;
 
 	dput(nd->dentry);
-	nd->dentry = dentry;
+	nd->dentry = path.dentry;
+	if (nd->mnt != path.mnt)
+		mntput(nd->mnt);
+	nd->mnt = path.mnt;
 	error = -EISDIR;
-	if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode))
+	if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
 		goto exit;
 ok:
 	error = may_open(nd, acc_mode, flag);
@@ -1500,7 +1519,9 @@ ok:
 	return 0;
 
 exit_dput:
-	dput(dentry);
+	dput(path.dentry);
+	if (nd->mnt != path.mnt)
+		mntput(path.mnt);
 exit:
 	path_release(nd);
 	return error;
@@ -1520,18 +1541,15 @@ do_link:
 	 * are done. Procfs-like symlinks just set LAST_BIND.
 	 */
 	nd->flags |= LOOKUP_PARENT;
-	error = security_inode_follow_link(dentry, nd);
+	error = security_inode_follow_link(path.dentry, nd);
 	if (error)
 		goto exit_dput;
-	error = __do_follow_link(dentry, nd);
-	dput(dentry);
+	error = __do_follow_link(&path, nd);
 	if (error)
 		return error;
 	nd->flags &= ~LOOKUP_PARENT;
-	if (nd->last_type == LAST_BIND) {
-		dentry = nd->dentry;
+	if (nd->last_type == LAST_BIND)
 		goto ok;
-	}
 	error = -EISDIR;
 	if (nd->last_type != LAST_NORM)
 		goto exit;
@@ -1546,7 +1564,8 @@ do_link:
 	}
 	dir = nd->dentry;
 	down(&dir->d_inode->i_sem);
-	dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+	path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+	path.mnt = nd->mnt;
 	putname(nd->last.name);
 	goto do_last;
 }