namei: saner calling conventions for filename_parentat()

a) make it reject ERR_PTR() for name
b) make it putname(name) on all other failure exits
c) make it return name on success

again, simplifies the callers

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

diff --git a/fs/namei.c b/fs/namei.c
index 628b6eb9415fed66cfc73376e42c49ee86495434..484b73cb95e3e0f4befb47e96f7ad159f0363df4 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2166,13 +2166,16 @@ static int path_parentat(int dfd, const struct filename *name,
        return err;
 }
 
-static int filename_parentat(int dfd, struct filename *name,
+static struct filename *filename_parentat(int dfd, struct filename *name,
                                unsigned int flags, struct path *parent,
                                struct qstr *last, int *type)
 {
        int retval;
-       struct nameidata nd, *saved_nd = set_nameidata(&nd);
+       struct nameidata nd, *saved_nd;
 
+       if (IS_ERR(name))
+               return name;
+       saved_nd = set_nameidata(&nd);
        retval = path_parentat(dfd, name, flags | LOOKUP_RCU, &nd, parent);
        if (unlikely(retval == -ECHILD))
                retval = path_parentat(dfd, name, flags, &nd, parent);
@@ -2183,32 +2186,30 @@ static int filename_parentat(int dfd, struct filename *name,
                *last = nd.last;
                *type = nd.last_type;
                audit_inode(name, parent->dentry, LOOKUP_PARENT);
+       } else {
+               putname(name);
+               name = ERR_PTR(retval);
        }
        restore_nameidata(saved_nd);
-       return retval;
+       return name;
 }
 
 /* does lookup, returns the object with parent locked */
 struct dentry *kern_path_locked(const char *name, struct path *path)
 {
-       struct filename *filename = getname_kernel(name);
+       struct filename *filename;
+       struct dentry *d;
        struct qstr last;
        int type;
-       struct dentry *d;
-       int err;
 
+       filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path,
+                                   &last, &type);
        if (IS_ERR(filename))
                return ERR_CAST(filename);
-
-       err = filename_parentat(AT_FDCWD, filename, 0, path, &last, &type);
-       if (err) {
-               d = ERR_PTR(err);
-               goto out;
-       }
-       if (type != LAST_NORM) {
+       if (unlikely(type != LAST_NORM)) {
                path_put(path);
-               d = ERR_PTR(-EINVAL);
-               goto out;
+               putname(filename);
+               return ERR_PTR(-EINVAL);
        }
        mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT);
        d = __lookup_hash(&last, path->dentry, 0);
@@ -2216,7 +2217,6 @@ struct dentry *kern_path_locked(const char *name, struct path *path)
                mutex_unlock(&path->dentry->d_inode->i_mutex);
                path_put(path);
        }
-out:
        putname(filename);
        return d;
 }
@@ -2325,21 +2325,9 @@ user_path_parent(int dfd, const char __user *path,
                 int *type,
                 unsigned int flags)
 {
-       struct filename *s = getname(path);
-       int error;
-
        /* only LOOKUP_REVAL is allowed in extra flags */
-       flags &= LOOKUP_REVAL;
-
-       if (IS_ERR(s))
-               return s;
-
-       error = filename_parentat(dfd, s, flags, parent, last, type);
-       if (error) {
-               putname(s);
-               s = ERR_PTR(error);
-       }
-       return s;
+       return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL,
+                                parent, last, type);
 }
 
 /**
@@ -3403,25 +3391,21 @@ static struct dentry *filename_create(int dfd, struct filename *name,
        int error;
        bool is_dir = (lookup_flags & LOOKUP_DIRECTORY);
 
-       if (IS_ERR(name))
-               return ERR_CAST(name);
        /*
         * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
         * other flags passed in are ignored!
         */
        lookup_flags &= LOOKUP_REVAL;
 
-       error = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
-       if (error) {
-               putname(name);
-               return ERR_PTR(error);
-       }
+       name = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
+       if (IS_ERR(name))
+               return ERR_CAST(name);
 
        /*
         * Yucky last component or no last component at all?
         * (foo/., foo/.., /////)
         */
-       if (type != LAST_NORM)
+       if (unlikely(type != LAST_NORM))
                goto out;
 
        /* don't fail immediately if it's r/o, at least try to report other errors */