linux-kernel - Re: [PATCH] f2fs: support to disable linear lookup fallback

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CALBjLoDnzALdShsEzii6pK+fxgbeNVh8weKVtb=PyFJ3XgS1NA@mail.gmail.com>
Date: Mon, 31 Mar 2025 09:31:20 -0700
From: Daniel Lee <chullee@...gle.com>
To: Chao Yu <chao@...nel.org>
Cc: jaegeuk@...nel.org, linux-f2fs-devel@...ts.sourceforge.net, 
	linux-kernel@...r.kernel.org, Gabriel Krisman Bertazi <krisman@...e.de>
Subject: Re: [PATCH] f2fs: support to disable linear lookup fallback

On Sun, Mar 30, 2025 at 7:54 PM Chao Yu <chao@...nel.org> wrote:
>
> After commit 91b587ba79e1 ("f2fs: Introduce linear search for
> dentries"), f2fs forced to use linear lookup whenever a hash-based
> lookup fails on casefolded directory, it may affect performance
> for scenarios: a) create a new file w/ filename it doesn't exist
> in directory, b) lookup a file which may be removed.
>
> This patch supports to disable linear lookup fallback, so, once there
> is a solution for commit 5c26d2f1d3f5 ("unicode: Don't special case
> ignorable code points") to fix red heart unicode issue, then we can
> set an encodeing flag to disable the fallback for performance recovery.
>
> The way is kept in line w/ ext4, refer to commit 9e28059d5664 ("ext4:
> introduce linear search for dentries").
>
> Cc: Daniel Lee <chullee@...gle.com>
> Cc: Gabriel Krisman Bertazi <krisman@...e.de>
> Signed-off-by: Chao Yu <chao@...nel.org>
> ---
>  fs/f2fs/dir.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index 5a63ff0df03b..e12445afb95a 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -366,7 +366,8 @@ struct f2fs_dir_entry *__f2fs_find_entry(struct inode *dir,
>
>  out:
>  #if IS_ENABLED(CONFIG_UNICODE)
> -       if (IS_CASEFOLDED(dir) && !de && use_hash) {
> +       if (IS_CASEFOLDED(dir) && !de && use_hash &&
> +               !sb_no_casefold_compat_fallback(dir->i_sb)) {


Would it be beneficial to evaluate
!sb_no_casefold_compat_fallback(dir->i_sb) first for short-circuiting?


>
>                 use_hash = false;
>                 goto start_find_entry;
>         }
> --
> 2.49.0
>