[PATCH 11/20] VFS/namei: use terminate_walk when symlink lookup fails.

NeilBrown
2015-03-23T02:39:09Z

Currently following a symlink never uses rcu-walk, so
terminate_walk isn't needed.
That will change in a future patch. In preparation, change
some
path_put_condtional()
path_put()
sequences to
path_to_nameidata()
terminate_walk()

These sequence are identical when in ref-walk, and correct when in
rcu-walk.

Also change two path_put() calls to equivalent terminate_walk().

Signed-off-by: NeilBrown <neilb@suse.de>
---
fs/namei.c | 40 ++++++++++++++++++++--------------------
1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 6ac163212429..1a8cc0e47df6 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -748,6 +748,18 @@ static inline char *nd_get_link(struct nameidata *nd)
return nd->saved_names[nd->depth];
}

+static void terminate_walk(struct nameidata *nd)
+{
+ if (!(nd->flags & LOOKUP_RCU)) {
+ path_put(&nd->path);
+ } else {
+ nd->flags &= ~LOOKUP_RCU;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ }
+}
+
static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
{
struct inode *inode = link->dentry->d_inode;
@@ -798,8 +810,8 @@ static inline int may_follow_link(struct path *link, struct nameidata *nd)
return 0;

audit_log_link_denied("follow_link", link);
- path_put_conditional(link, nd);
- path_put(&nd->path);
+ path_to_nameidata(link, nd);
+ terminate_walk(nd);
return -EACCES;
}

@@ -911,7 +923,7 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
s = nd_get_link(nd);
if (s) {
if (unlikely(IS_ERR(s))) {
- path_put(&nd->path);
+ terminate_walk(nd);
put_link(nd, link, *p);
return PTR_ERR(s);
}
@@ -933,7 +945,7 @@ follow_link(struct path *link, struct nameidata *nd, void **p)

out_put_nd_path:
*p = NULL;
- path_put(&nd->path);
+ terminate_walk(nd);
path_put(link);
return error;
}
@@ -1564,18 +1576,6 @@ static inline int handle_dots(struct nameidata *nd, int type)
return 0;
}

-static void terminate_walk(struct nameidata *nd)
-{
- if (!(nd->flags & LOOKUP_RCU)) {
- path_put(&nd->path);
- } else {
- nd->flags &= ~LOOKUP_RCU;
- if (!(nd->flags & LOOKUP_ROOT))
- nd->root.mnt = NULL;
- rcu_read_unlock();
- }
-}
-
/*
* Do we need to follow links? We _really_ want to be able
* to do this check without having to look at inode->i_op,
@@ -1647,8 +1647,8 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd)
int res;

if (unlikely(nd->link_count >= MAX_NESTED_LINKS)) {
- path_put_conditional(path, nd);
- path_put(&nd->path);
+ path_to_nameidata(path, nd);
+ terminate_walk(nd);
return -ELOOP;
}
BUG_ON(nd->depth >= MAX_NESTED_LINKS);
@@ -3270,8 +3270,8 @@ static struct file *path_openat(int dfd, struct filename *pathname,
struct path link = path;
void *cookie;
if (!(nd->flags & LOOKUP_FOLLOW)) {
- path_put_conditional(&path, nd);
- path_put(&nd->path);
+ path_to_nameidata(&path, nd);
+ terminate_walk(nd);
error = -ELOOP;
break;
}