Re: [PATCH 1/2] fs: make do_mkdirat() take struct filename

[Jens Axboe <axboe@kernel.dk>]

On 11/15/20 9:45 PM, Dmitry Kadashev wrote:
> Pass in the struct filename pointers instead of the user string, and
> update the three callers to do the same. This is heavily based on
> commit dbea8d345177 ("fs: make do_renameat2() take struct filename").
> 
> This behaves like do_unlinkat() and do_renameat2().

Al, are you OK with this patch? Leaving it quoted, though you should
have the original too.

> 
> Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
> ---
>  fs/internal.h |  1 +
>  fs/namei.c    | 20 ++++++++++++++------
>  2 files changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/internal.h b/fs/internal.h
> index 6fd14ea213c3..23b8b427dbd2 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -80,6 +80,7 @@ long do_unlinkat(int dfd, struct filename *name);
>  int may_linkat(struct path *link);
>  int do_renameat2(int olddfd, struct filename *oldname, int newdfd,
>  		 struct filename *newname, unsigned int flags);
> +long do_mkdirat(int dfd, struct filename *name, umode_t mode);
>  
>  /*
>   * namespace.c
> diff --git a/fs/namei.c b/fs/namei.c
> index 03d0e11e4f36..9d26a51f3f54 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3654,17 +3654,23 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
>  }
>  EXPORT_SYMBOL(vfs_mkdir);
>  
> -static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
> +long do_mkdirat(int dfd, struct filename *name, umode_t mode)
>  {
>  	struct dentry *dentry;
>  	struct path path;
>  	int error;
>  	unsigned int lookup_flags = LOOKUP_DIRECTORY;
>  
> +	if (IS_ERR(name))
> +		return PTR_ERR(name);
> +
>  retry:
> -	dentry = user_path_create(dfd, pathname, &path, lookup_flags);
> -	if (IS_ERR(dentry))
> -		return PTR_ERR(dentry);
> +	name->refcnt++; /* filename_create() drops our ref */
> +	dentry = filename_create(dfd, name, &path, lookup_flags);
> +	if (IS_ERR(dentry)) {
> +		error = PTR_ERR(dentry);
> +		goto out;
> +	}
>  
>  	if (!IS_POSIXACL(path.dentry->d_inode))
>  		mode &= ~current_umask();
> @@ -3676,17 +3682,19 @@ static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
>  		lookup_flags |= LOOKUP_REVAL;
>  		goto retry;
>  	}
> +out:
> +	putname(name);
>  	return error;
>  }
>  
>  SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
>  {
> -	return do_mkdirat(dfd, pathname, mode);
> +	return do_mkdirat(dfd, getname(pathname), mode);
>  }
>  
>  SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
>  {
> -	return do_mkdirat(AT_FDCWD, pathname, mode);
> +	return do_mkdirat(AT_FDCWD, getname(pathname), mode);
>  }
>  
>  int vfs_rmdir(struct inode *dir, struct dentry *dentry)
> 


-- 
Jens Axboe