tidy the trailing symlinks traversal up

* pull the handling of current->total_link_count into
__do_follow_link()
* put the common "do ->put_link() if needed and path_put() the link"
  stuff into a helper (put_link(nd, link, cookie))
* rename __do_follow_link() to follow_link(), while we are at it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 26 insertions, 45 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 017c3fa3a08..0a601cae23d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -737,14 +737,31 @@ static inline void path_to_nameidata(const struct path *path,
         nd->path.dentry = path->dentry;
 }
 
+static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
+{
+        struct inode *inode = link->dentry->d_inode;
+        if (!IS_ERR(cookie) && inode->i_op->put_link)
+                inode->i_op->put_link(link->dentry, nd, cookie);
+        path_put(link);
+}
+
 static __always_inline int
-__do_follow_link(const struct path *link, struct nameidata *nd, void **p)
+follow_link(struct path *link, struct nameidata *nd, void **p)
 {
         int error;
         struct dentry *dentry = link->dentry;
 
         BUG_ON(nd->flags & LOOKUP_RCU);
 
+        if (unlikely(current->total_link_count >= 40)) {
+                *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
+                path_put_conditional(link, nd);
+                path_put(&nd->path);
+                return -ELOOP;
+        }
+        cond_resched();
+        current->total_link_count++;
+
         touch_atime(link->mnt, dentry);
         nd_set_link(nd, NULL);
 
@@ -1356,21 +1373,12 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd)
         do {
                 struct path link = *path;
                 void *cookie;
-                if (unlikely(current->total_link_count >= 40)) {
-                        path_put_conditional(path, nd);
-                        path_put(&nd->path);
-                        res = -ELOOP;
-                        break;
-                }
-                cond_resched();
-                current->total_link_count++;
-                res = __do_follow_link(&link, nd, &cookie);
+
+                res = follow_link(&link, nd, &cookie);
                 if (!res)
                         res = walk_component(nd, path, &nd->last,
                                              nd->last_type, LOOKUP_FOLLOW);
-                if (!IS_ERR(cookie) && link.dentry->d_inode->i_op->put_link)
-                        link.dentry->d_inode->i_op->put_link(link.dentry, nd, cookie);
-                path_put(&link);
+                put_link(nd, &link, cookie);
         } while (res > 0);
 
         current->link_count--;
@@ -1619,27 +1627,15 @@ static int path_lookupat(int dfd, const char *name,
         err = link_path_walk(name, nd);
 
         if (!err && !(flags & LOOKUP_PARENT)) {
-                int count = 0;
                 err = lookup_last(nd, &path);
                 while (err > 0) {
                         void *cookie;
                         struct path link = path;
-                        struct inode *inode = link.dentry->d_inode;
-
-                        if (count++ > 32) {
-                                path_put_conditional(&path, nd);
-                                path_put(&nd->path);
-                                err = -ELOOP;
-                                break;
-                        }
-                        cond_resched();
                         nd->flags |= LOOKUP_PARENT;
-                        err = __do_follow_link(&link, nd, &cookie);
+                        err = follow_link(&link, nd, &cookie);
                         if (!err)
                                 err = lookup_last(nd, &path);
-                        if (!IS_ERR(cookie) && inode->i_op->put_link)
-                                inode->i_op->put_link(link.dentry, nd, cookie);
-                        path_put(&link);
+                        put_link(nd, &link, cookie);
                 }
         }
 
@@ -2298,7 +2294,6 @@ static struct file *path_openat(int dfd, const char *pathname,
         struct file *base = NULL;
         struct file *filp;
         struct path path;
-        int count = 0;
         int error;
 
         filp = get_empty_filp();
@@ -2322,35 +2317,21 @@ static struct file *path_openat(int dfd, const char *pathname,
         filp = do_last(nd, &path, op, pathname);
         while (unlikely(!filp)) { /* trailing symlink */
                 struct path link = path;
-                struct inode *linki = link.dentry->d_inode;
                 void *cookie;
-                if (!(nd->flags & LOOKUP_FOLLOW) || count++ == 32) {
+                if (!(nd->flags & LOOKUP_FOLLOW)) {
                         path_put_conditional(&path, nd);
                         path_put(&nd->path);
                         filp = ERR_PTR(-ELOOP);
                         break;
                 }
-                /*
-                 * This is subtle. Instead of calling do_follow_link() we do
-                 * the thing by hands. The reason is that this way we have zero
-                 * link_count and path_walk() (called from ->follow_link)
-                 * honoring LOOKUP_PARENT.  After that we have the parent and
-                 * last component, i.e. we are in the same situation as after
-                 * the first path_walk().  Well, almost - if the last component
-                 * is normal we get its copy stored in nd->last.name and we will
-                 * have to putname() it when we are done. Procfs-like symlinks
-                 * just set LAST_BIND.
-                 */
                 nd->flags |= LOOKUP_PARENT;
                 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
-                error = __do_follow_link(&link, nd, &cookie);
+                error = follow_link(&link, nd, &cookie);
                 if (unlikely(error))
                         filp = ERR_PTR(error);
                 else
                         filp = do_last(nd, &path, op, pathname);
-                if (!IS_ERR(cookie) && linki->i_op->put_link)
-                        linki->i_op->put_link(link.dentry, nd, cookie);
-                path_put(&link);
+                put_link(nd, &link, cookie);
         }
 out:
         if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))