new helpers: kern_path_create/user_path_create

combination of kern_path_parent() and lookup_create().  Does *not*
expose struct nameidata to caller.  Syscalls converted to that...

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

1 files changed, 76 insertions, 78 deletions

diff --git a/fs/namei.c b/fs/namei.c
index f49d6abfa799..b292eb03d9d2 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2311,6 +2311,35 @@ fail:
 }
 EXPORT_SYMBOL_GPL(lookup_create);
 
+struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
+{
+        struct nameidata nd;
+        struct dentry *res;
+        int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
+        if (error)
+                return ERR_PTR(error);
+        res = lookup_create(&nd, is_dir);
+        if (IS_ERR(res)) {
+                mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+                path_put(&nd.path);
+        }
+        *path = nd.path;
+        return res;
+}
+EXPORT_SYMBOL(kern_path_create);
+
+struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
+{
+        char *tmp = getname(pathname);
+        struct dentry *res;
+        if (IS_ERR(tmp))
+                return ERR_CAST(tmp);
+        res = kern_path_create(dfd, tmp, path, is_dir);
+        putname(tmp);
+        return res;
+}
+EXPORT_SYMBOL(user_path_create);
+
 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 {
         int error = may_create(dir, dentry);
@@ -2359,54 +2388,46 @@ static int may_mknod(mode_t mode)
 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
                 unsigned, dev)
 {
-        int error;
-        char *tmp;
         struct dentry *dentry;
-        struct nameidata nd;
+        struct path path;
+        int error;
 
         if (S_ISDIR(mode))
                 return -EPERM;
 
-        error = user_path_parent(dfd, filename, &nd, &tmp);
-        if (error)
-                return error;
+        dentry = user_path_create(dfd, filename, &path, 0);
+        if (IS_ERR(dentry))
+                return PTR_ERR(dentry);
 
-        dentry = lookup_create(&nd, 0);
-        if (IS_ERR(dentry)) {
-                error = PTR_ERR(dentry);
-                goto out_unlock;
-        }
-        if (!IS_POSIXACL(nd.path.dentry->d_inode))
+        if (!IS_POSIXACL(path.dentry->d_inode))
                 mode &= ~current_umask();
         error = may_mknod(mode);
         if (error)
                 goto out_dput;
-        error = mnt_want_write(nd.path.mnt);
+        error = mnt_want_write(path.mnt);
         if (error)
                 goto out_dput;
-        error = security_path_mknod(&nd.path, dentry, mode, dev);
+        error = security_path_mknod(&path, dentry, mode, dev);
         if (error)
                 goto out_drop_write;
         switch (mode & S_IFMT) {
                 case 0: case S_IFREG:
-                        error = vfs_create(nd.path.dentry->d_inode,dentry,mode,NULL);
+                        error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
                         break;
                 case S_IFCHR: case S_IFBLK:
-                        error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
+                        error = vfs_mknod(path.dentry->d_inode,dentry,mode,
                                         new_decode_dev(dev));
                         break;
                 case S_IFIFO: case S_IFSOCK:
-                        error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
+                        error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
                         break;
         }
 out_drop_write:
-        mnt_drop_write(nd.path.mnt);
+        mnt_drop_write(path.mnt);
 out_dput:
         dput(dentry);
-out_unlock:
-        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-        path_put(&nd.path);
-        putname(tmp);
+        mutex_unlock(&path.dentry->d_inode->i_mutex);
+        path_put(&path);
 
         return error;
 }
@@ -2439,38 +2460,29 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 
 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
 {
-        int error = 0;
-        char * tmp;
         struct dentry *dentry;
-        struct nameidata nd;
-
-        error = user_path_parent(dfd, pathname, &nd, &tmp);
-        if (error)
-                goto out_err;
+        struct path path;
+        int error;
 
-        dentry = lookup_create(&nd, 1);
-        error = PTR_ERR(dentry);
+        dentry = user_path_create(dfd, pathname, &path, 1);
         if (IS_ERR(dentry))
-                goto out_unlock;
+                return PTR_ERR(dentry);
 
-        if (!IS_POSIXACL(nd.path.dentry->d_inode))
+        if (!IS_POSIXACL(path.dentry->d_inode))
                 mode &= ~current_umask();
-        error = mnt_want_write(nd.path.mnt);
+        error = mnt_want_write(path.mnt);
         if (error)
                 goto out_dput;
-        error = security_path_mkdir(&nd.path, dentry, mode);
+        error = security_path_mkdir(&path, dentry, mode);
         if (error)
                 goto out_drop_write;
-        error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
+        error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
 out_drop_write:
-        mnt_drop_write(nd.path.mnt);
+        mnt_drop_write(path.mnt);
 out_dput:
         dput(dentry);
-out_unlock:
-        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-        path_put(&nd.path);
-        putname(tmp);
-out_err:
+        mutex_unlock(&path.dentry->d_inode->i_mutex);
+        path_put(&path);
         return error;
 }
 
@@ -2730,38 +2742,31 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
 {
         int error;
         char *from;
-        char *to;
         struct dentry *dentry;
-        struct nameidata nd;
+        struct path path;
 
         from = getname(oldname);
         if (IS_ERR(from))
                 return PTR_ERR(from);
 
-        error = user_path_parent(newdfd, newname, &nd, &to);
-        if (error)
-                goto out_putname;
-
-        dentry = lookup_create(&nd, 0);
+        dentry = user_path_create(newdfd, newname, &path, 0);
         error = PTR_ERR(dentry);
         if (IS_ERR(dentry))
-                goto out_unlock;
+                goto out_putname;
 
-        error = mnt_want_write(nd.path.mnt);
+        error = mnt_want_write(path.mnt);
         if (error)
                 goto out_dput;
-        error = security_path_symlink(&nd.path, dentry, from);
+        error = security_path_symlink(&path, dentry, from);
         if (error)
                 goto out_drop_write;
-        error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
+        error = vfs_symlink(path.dentry->d_inode, dentry, from);
 out_drop_write:
-        mnt_drop_write(nd.path.mnt);
+        mnt_drop_write(path.mnt);
 out_dput:
         dput(dentry);
-out_unlock:
-        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-        path_put(&nd.path);
-        putname(to);
+        mutex_unlock(&path.dentry->d_inode->i_mutex);
+        path_put(&path);
 out_putname:
         putname(from);
         return error;
@@ -2826,11 +2831,9 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
                 int, newdfd, const char __user *, newname, int, flags)
 {
         struct dentry *new_dentry;
-        struct nameidata nd;
-        struct path old_path;
+        struct path old_path, new_path;
         int how = 0;
         int error;
-        char *to;
 
         if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
                 return -EINVAL;
@@ -2852,32 +2855,27 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
         if (error)
                 return error;
 
-        error = user_path_parent(newdfd, newname, &nd, &to);
-        if (error)
-                goto out;
-        error = -EXDEV;
-        if (old_path.mnt != nd.path.mnt)
-                goto out_release;
-        new_dentry = lookup_create(&nd, 0);
+        new_dentry = user_path_create(newdfd, newname, &new_path, 0);
         error = PTR_ERR(new_dentry);
         if (IS_ERR(new_dentry))
-                goto out_unlock;
-        error = mnt_want_write(nd.path.mnt);
+                goto out;
+
+        error = -EXDEV;
+        if (old_path.mnt != new_path.mnt)
+                goto out_dput;
+        error = mnt_want_write(new_path.mnt);
         if (error)
                 goto out_dput;
-        error = security_path_link(old_path.dentry, &nd.path, new_dentry);
+        error = security_path_link(old_path.dentry, &new_path, new_dentry);
         if (error)
                 goto out_drop_write;
-        error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
+        error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
 out_drop_write:
-        mnt_drop_write(nd.path.mnt);
+        mnt_drop_write(new_path.mnt);
 out_dput:
         dput(new_dentry);
-out_unlock:
-        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
-out_release:
-        path_put(&nd.path);
-        putname(to);
+        mutex_unlock(&new_path.dentry->d_inode->i_mutex);
+        path_put(&new_path);
 out:
         path_put(&old_path);