Re: [PATCH 0/9][btrfs-progs] Remove unused dirstream variable

[David Sterba <dsterba@suse.cz>]

On Sat, Dec 09, 2023 at 07:53:20PM +0100, Goffredo Baroncelli wrote:
> From: Goffredo Baroncelli <kreijack@inwind.it>
> 
> For historical reason, the helpers [btrfs_]open_[file_or_]dir() work with
> directory returning the 'fd' and a 'dirstream' variable returned by
> opendir(3).
> 
> If the path is a file, the 'fd' is computed from open(2) and
> dirstream is set to NULL.
> If the path is a directory, first the directory is opened by opendir(3), then
> the 'fd' is computed using dirfd(3).
> However the 'dirstream' returned by opendir(3) is left open until 'fd'
> is not needed anymore.
> 
> In near every case the 'dirstream' variable is not used. Only 'fd' is
> used.

As I'm reading dirfd manual page, dirfd returns the internal file
descriptor of the dirstream and it gets closed after call to closedir().
This means if we pass a directory and want a file descriptor then its
lifetime matches the correspoinding DIR.

> A call to close_file_or_dir() freed both 'fd' and 'dirstream'.
> 
> Aim of this patch set is to getrid of this complexity; when the path of
> a directory is passed, the fd is get directly using open(path, O_RDONLY):
> so we don't need to use readdir(3) and to maintain the not used variable
> 'dirstream'.

Does this work the same way as with the dirstream?