linux-kernel - Re: [PATCH v11 2/4] fs: Add standard casefolding support

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Date:   Wed, 8 Jul 2020 01:36:33 -0700
From:   Daniel Rosenberg <drosen@...gle.com>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     "Theodore Ts'o" <tytso@....edu>, linux-ext4@...r.kernel.org,
        Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-fscrypt@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        kernel-team@...roid.com
Subject: Re: [PATCH v11 2/4] fs: Add standard casefolding support

On Tue, Jul 7, 2020 at 9:12 PM Eric Biggers <ebiggers@...nel.org> wrote:
>
> On Tue, Jul 07, 2020 at 08:05:50PM -0700, Daniel Rosenberg wrote:
> > +/**
> > + * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems
> > + * @dentry:  dentry whose name we are checking against
> > + * @len:     len of name of dentry
> > + * @str:     str pointer to name of dentry
> > + * @name:    Name to compare against
> > + *
> > + * Return: 0 if names match, 1 if mismatch, or -ERRNO
> > + */
> > +int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
> > +                       const char *str, const struct qstr *name)
> > +{
> > +     const struct dentry *parent = READ_ONCE(dentry->d_parent);
> > +     const struct inode *inode = READ_ONCE(parent->d_inode);
>
> How about calling the 'inode' variable 'dir' instead?
>
> That would help avoid confusion about what is the directory and what is a file
> in the directory.
>
> Likewise in generic_ci_d_hash().
>
> > +/**
> > + * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems
> > + * @dentry:  dentry whose name we are hashing
>
> This comment for @dentry needs to be updated.
>
> It's the parent dentry, not the dentry whose name we are hashing.
>
> > + * @str:     qstr of name whose hash we should fill in
> > + *
> > + * Return: 0 if hash was successful, or -ERRNO
>
> As I mentioned on v9, this can also return 0 if the hashing was not done because
> it wants to fallback to the standard hashing.  Can you please fix the comment?
>
> > +int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
> > +{
> > +     const struct inode *inode = READ_ONCE(dentry->d_inode);
> > +     struct super_block *sb = dentry->d_sb;
> > +     const struct unicode_map *um = sb->s_encoding;
> > +     int ret = 0;
> > +
> > +     if (!inode || !needs_casefold(inode))
> > +             return 0;
> > +
> > +     ret = utf8_casefold_hash(um, dentry, str);
> > +     if (ret < 0)
> > +             goto err;
> > +
> > +     return 0;
> > +err:
> > +     if (sb_has_strict_encoding(sb))
> > +             ret = -EINVAL;
> > +     else
> > +             ret = 0;
> > +     return ret;
> > +}
>
> On v9, Gabriel suggested simplifying this to:
>
>         ret = utf8_casefold_hash(um, dentry, str);
>         if (ret < 0 && sb_has_enc_strict_mode(sb))
>                 return -EINVAL;
>         return 0;
>
> Any reason not to do that?
>
> - Eric

Guh, I remember making those changes, must've lost them in a rebase :(
I'll resend shortly.
-Daniel