1 files changed, 54 insertions, 93 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 5b4eed221530..092ac5667ec7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1725,30 +1725,35 @@ static int pick_link(struct nameidata *nd, struct path *link,
 	return 1;
 }
 
+enum {WALK_FOLLOW = 1, WALK_MORE = 2};
+
 /*
  * Do we need to follow links? We _really_ want to be able
  * to do this check without having to look at inode->i_op,
  * so we keep a cache of "no, this doesn't need follow_link"
  * for the common case.
  */
-static inline int should_follow_link(struct nameidata *nd, struct path *link,
-				     int follow,
-				     struct inode *inode, unsigned seq)
+static inline int step_into(struct nameidata *nd, struct path *path,
+			    int flags, struct inode *inode, unsigned seq)
 {
-	if (likely(!d_is_symlink(link->dentry)))
-		return 0;
-	if (!follow)
+	if (!(flags & WALK_MORE) && nd->depth)
+		put_link(nd);
+	if (likely(!d_is_symlink(path->dentry)) ||
+	   !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) {
+		/* not a symlink or should not follow */
+		path_to_nameidata(path, nd);
+		nd->inode = inode;
+		nd->seq = seq;
 		return 0;
+	}
 	/* make sure that d_is_symlink above matches inode */
 	if (nd->flags & LOOKUP_RCU) {
-		if (read_seqcount_retry(&link->dentry->d_seq, seq))
+		if (read_seqcount_retry(&path->dentry->d_seq, seq))
 			return -ECHILD;
 	}
-	return pick_link(nd, link, inode, seq);
+	return pick_link(nd, path, inode, seq);
 }
 
-enum {WALK_GET = 1, WALK_PUT = 2};
-
 static int walk_component(struct nameidata *nd, int flags)
 {
 	struct path path;
@@ -1762,7 +1767,7 @@ static int walk_component(struct nameidata *nd, int flags)
 	 */
 	if (unlikely(nd->last_type != LAST_NORM)) {
 		err = handle_dots(nd, nd->last_type);
-		if (flags & WALK_PUT)
+		if (!(flags & WALK_MORE) && nd->depth)
 			put_link(nd);
 		return err;
 	}
@@ -1789,15 +1794,7 @@ static int walk_component(struct nameidata *nd, int flags)
 		inode = d_backing_inode(path.dentry);
 	}
 
-	if (flags & WALK_PUT)
-		put_link(nd);
-	err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq);
-	if (unlikely(err))
-		return err;
-	path_to_nameidata(&path, nd);
-	nd->inode = inode;
-	nd->seq = seq;
-	return 0;
+	return step_into(nd, &path, flags, inode, seq);
 }
 
 /*
@@ -2104,9 +2101,10 @@ OK:
 			if (!name)
 				return 0;
 			/* last component of nested symlink */
-			err = walk_component(nd, WALK_GET | WALK_PUT);
+			err = walk_component(nd, WALK_FOLLOW);
 		} else {
-			err = walk_component(nd, WALK_GET);
+			/* not the last component */
+			err = walk_component(nd, WALK_FOLLOW | WALK_MORE);
 		}
 		if (err < 0)
 			return err;
@@ -2248,12 +2246,7 @@ static inline int lookup_last(struct nameidata *nd)
 		nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 
 	nd->flags &= ~LOOKUP_PARENT;
-	return walk_component(nd,
-			nd->flags & LOOKUP_FOLLOW
-				? nd->depth
-					? WALK_PUT | WALK_GET
-					: WALK_GET
-				: 0);
+	return walk_component(nd, 0);
 }
 
 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
@@ -2558,28 +2551,9 @@ int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
 }
 EXPORT_SYMBOL(user_path_at_empty);
 
-/*
- * NB: most callers don't do anything directly with the reference to the
- *     to struct filename, but the nd->last pointer points into the name string
- *     allocated by getname. So we must hold the reference to it until all
- *     path-walking is complete.
- */
-static inline struct filename *
-user_path_parent(int dfd, const char __user *path,
-		 struct path *parent,
-		 struct qstr *last,
-		 int *type,
-		 unsigned int flags)
-{
-	/* only LOOKUP_REVAL is allowed in extra flags */
-	return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL,
-				 parent, last, type);
-}
-
 /**
  * mountpoint_last - look up last component for umount
  * @nd:   pathwalk nameidata - currently pointing at parent directory of "last"
- * @path: pointer to container for result
  *
  * This is a special lookup_last function just for umount. In this case, we
  * need to resolve the path without doing any revalidation.
@@ -2592,23 +2566,20 @@ user_path_parent(int dfd, const char __user *path,
  *
  * Returns:
  * -error: if there was an error during lookup. This includes -ENOENT if the
- *         lookup found a negative dentry. The nd->path reference will also be
- *         put in this case.
+ *         lookup found a negative dentry.
  *
- * 0:      if we successfully resolved nd->path and found it to not to be a
- *         symlink that needs to be followed. "path" will also be populated.
- *         The nd->path reference will also be put.
+ * 0:      if we successfully resolved nd->last and found it to not to be a
+ *         symlink that needs to be followed.
  *
  * 1:      if we successfully resolved nd->last and found it to be a symlink
- *         that needs to be followed. "path" will be populated with the path
- *         to the link, and nd->path will *not* be put.
+ *         that needs to be followed.
  */
 static int
-mountpoint_last(struct nameidata *nd, struct path *path)
+mountpoint_last(struct nameidata *nd)
 {
 	int error = 0;
-	struct dentry *dentry;
 	struct dentry *dir = nd->path.dentry;
+	struct path path;
 
 	/* If we're in rcuwalk, drop out of it to handle last component */
 	if (nd->flags & LOOKUP_RCU) {
@@ -2622,37 +2593,28 @@ mountpoint_last(struct nameidata *nd, struct path *path)
 		error = handle_dots(nd, nd->last_type);
 		if (error)
 			return error;
-		dentry = dget(nd->path.dentry);
+		path.dentry = dget(nd->path.dentry);
 	} else {
-		dentry = d_lookup(dir, &nd->last);
-		if (!dentry) {
+		path.dentry = d_lookup(dir, &nd->last);
+		if (!path.dentry) {
 			/*
 			 * No cached dentry. Mounted dentries are pinned in the
 			 * cache, so that means that this dentry is probably
 			 * a symlink or the path doesn't actually point
 			 * to a mounted dentry.
 			 */
-			dentry = lookup_slow(&nd->last, dir,
+			path.dentry = lookup_slow(&nd->last, dir,
 					     nd->flags | LOOKUP_NO_REVAL);
-			if (IS_ERR(dentry))
-				return PTR_ERR(dentry);
+			if (IS_ERR(path.dentry))
+				return PTR_ERR(path.dentry);
 		}
 	}
-	if (d_is_negative(dentry)) {
-		dput(dentry);
+	if (d_is_negative(path.dentry)) {
+		dput(path.dentry);
 		return -ENOENT;
 	}
-	if (nd->depth)
-		put_link(nd);
-	path->dentry = dentry;
-	path->mnt = nd->path.mnt;
-	error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW,
-				   d_backing_inode(dentry), 0);
-	if (unlikely(error))
-		return error;
-	mntget(path->mnt);
-	follow_mount(path);
-	return 0;
+	path.mnt = nd->path.mnt;
+	return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0);
 }
 
 /**
@@ -2672,13 +2634,19 @@ path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
 	if (IS_ERR(s))
 		return PTR_ERR(s);
 	while (!(err = link_path_walk(s, nd)) &&
-		(err = mountpoint_last(nd, path)) > 0) {
+		(err = mountpoint_last(nd)) > 0) {
 		s = trailing_symlink(nd);
 		if (IS_ERR(s)) {
 			err = PTR_ERR(s);
 			break;
 		}
 	}
+	if (!err) {
+		*path = nd->path;
+		nd->path.mnt = NULL;
+		nd->path.dentry = NULL;
+		follow_mount(path);
+	}
 	terminate_walk(nd);
 	return err;
 }
@@ -3335,18 +3303,11 @@ static int do_last(struct nameidata *nd,
 	seq = 0;	/* out of RCU mode, so the value doesn't matter */
 	inode = d_backing_inode(path.dentry);
 finish_lookup:
-	if (nd->depth)
-		put_link(nd);
-	error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW,
-				   inode, seq);
+	error = step_into(nd, &path, 0, inode, seq);
 	if (unlikely(error))
 		return error;
-
-	path_to_nameidata(&path, nd);
-	nd->inode = inode;
-	nd->seq = seq;
-	/* Why this, you ask?  _Now_ we might have grown LOOKUP_JUMPED... */
 finish_open:
+	/* Why this, you ask?  _Now_ we might have grown LOOKUP_JUMPED... */
 	error = complete_walk(nd);
 	if (error)
 		return error;
@@ -3861,8 +3822,8 @@ static long do_rmdir(int dfd, const char __user *pathname)
 	int type;
 	unsigned int lookup_flags = 0;
 retry:
-	name = user_path_parent(dfd, pathname,
-				&path, &last, &type, lookup_flags);
+	name = filename_parentat(dfd, getname(pathname), lookup_flags,
+				&path, &last, &type);
 	if (IS_ERR(name))
 		return PTR_ERR(name);
 
@@ -3991,8 +3952,8 @@ static long do_unlinkat(int dfd, const char __user *pathname)
 	struct inode *delegated_inode = NULL;
 	unsigned int lookup_flags = 0;
 retry:
-	name = user_path_parent(dfd, pathname,
-				&path, &last, &type, lookup_flags);
+	name = filename_parentat(dfd, getname(pathname), lookup_flags,
+				&path, &last, &type);
 	if (IS_ERR(name))
 		return PTR_ERR(name);
 
@@ -4491,15 +4452,15 @@ SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
 		target_flags = 0;
 
 retry:
-	from = user_path_parent(olddfd, oldname,
-				&old_path, &old_last, &old_type, lookup_flags);
+	from = filename_parentat(olddfd, getname(oldname), lookup_flags,
+				&old_path, &old_last, &old_type);
 	if (IS_ERR(from)) {
 		error = PTR_ERR(from);
 		goto exit;
 	}
 
-	to = user_path_parent(newdfd, newname,
-				&new_path, &new_last, &new_type, lookup_flags);
+	to = filename_parentat(newdfd, getname(newname), lookup_flags,
+				&new_path, &new_last, &new_type);
 	if (IS_ERR(to)) {
 		error = PTR_ERR(to);
 		goto exit1;