linux-ext4 - Re: generic_permission() optimization

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Message-ID: <CAHk-=whAi-La-PaktC83QhMWXyE4v3u6mzPwpE0bX7jhtRaitg@mail.gmail.com>
Date: Sat, 12 Apr 2025 16:12:18 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: "Theodore Ts'o" <tytso@....edu>
Cc: Mateusz Guzik <mjguzik@...il.com>, Christian Brauner <brauner@...nel.org>, 
	Al Viro <viro@...iv.linux.org.uk>, linux-fsdevel <linux-fsdevel@...r.kernel.org>, 
	Jan Kara <jack@...e.cz>, Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: generic_permission() optimization

On Sat, 12 Apr 2025 at 15:36, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> Indeed. I sent a query to the ext4 list (and I think you) about
> whether my test was even the right one.

.. I went back to my email archives, and it turns out that I _only_
sent it to you, not to the ext4 lists at all.

Oh well. It was this patch:

  --- a/fs/ext4/inode.c
  +++ b/fs/ext4/inode.c
  @@ -5011,6 +5011,11 @@ struct inode *__ext4_iget(...
        }

        brelse(iloc.bh);
  +
  +     /* Initialize the "no ACL's" state for the simple cases */
  +     if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) && !ei->i_file_acl)
  +             cache_no_acl(inode);
  +
        unlock_new_inode(inode);
        return inode;

and I think that's pretty much exactly the same patch as the one
Mateusz posted, just one line down (and the line numbers are different
because that patch was from five months ago and there's been some
unrelated changes since.

            Linus