Re: [PATCH 0/9][V2][btrfs-progs] Remove unused dirstream variable

[David Sterba <dsterba@suse.cz>]

On Thu, Feb 08, 2024 at 09:19:18PM +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.
> 
> 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'.
> 
> So each call of a legacy [btrfs_]open_[file_or_]dir() helper is
> replaced by a call to the new btrfs_open_[file_or_]dir_fd() functions.
> These functions return only the file descriptor.
> 
> Also close_file_or_dir() is not needed anymore.
> 
> The first patch, introduces the new helpers; the last patch removed the
> unused older helpers. The intermediate patches updated the code.
> 
> The 3rd patch updated also the add_seen_fsid() function. Before it
> stored the dirstream variable. But now it is not needed anymore.
> So we removed a parameter of the functions and a field in the structure.
> 
> In the 8th patch, the only occurrences where 'dirstream' is used was
> corrected: the dirstream is computed using fdopendir(3), and the cleanup
> is updated according.
> 
> The results is:
> - removed 7 functions
> - add 4 new functions
> - removed ~100 lines
> - removed 44 occurrences of an unused 'dirstream' variable.
> 
> 
> Changelog:
> 
> 09/dec/2023: V1: first issue
> 08/feb/2024: V2
> 	- rebased over 6.7
> 	- swapped the tests order inside the btrfs_open_fd2() function
> 	  to prevent the failure of the test 003-fi-resize-args
> 	- removed two new occurences of open_file_or_dir() inside
> 	  cmd_scrub_limit() (introduced after V1 pateches set)
> 
> 
> BR
> G.Baroncelli
> 
> 
> Goffredo Baroncelli (9):
>   Killing dirstream: add helpers
>   Killing dirstream: replace btrfs_open_dir with btrfs_open_dir_fd
>   Killing dirstream: replace btrfs_open_dir with btrfs_open_dir_fd
>   Killing dirstream: replace open_path_or_dev_mnt with btrfs_open_mnt_fd
>   Killing dirstream: replace open_file_or_dir3 with btrfs_open_fd2
>   Killing dirstream: replace btrfs_open_file_or_dir with
>     btrfs_open_file_or_dir_fd
>   Killing dirstream: replace open_file_or_dir with btrfs_open_fd2
>   Killing dirstream: remove open_file_or_dir3 from du_add_file
>   Killing dirstream: remove unused functions

Added to devel with some updates, thanks.