Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 23 Jun 2020 22:37:29 -0700
From:   Eric Biggers <ebiggers@kernel.org>
To:     Daniel Rosenberg <drosen@google.com>
Cc:     Theodore Ts'o <tytso@mit.edu>, linux-ext4@vger.kernel.org,
        Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>,
        linux-f2fs-devel@lists.sourceforge.net,
        linux-fscrypt@vger.kernel.org,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Richard Weinberger <richard@nod.at>,
        linux-mtd@lists.infradead.org,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Gabriel Krisman Bertazi <krisman@collabora.com>,
        kernel-team@android.com
Subject: Re: [PATCH v9 1/4] unicode: Add utf8_casefold_hash
Message-ID: <20200624053729.GE844@sol.localdomain>
References: <20200624043341.33364-1-drosen@google.com>
 <20200624043341.33364-2-drosen@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200624043341.33364-2-drosen@google.com>
Sender: linux-ext4-owner@vger.kernel.org
Precedence: bulk

On Tue, Jun 23, 2020 at 09:33:38PM -0700, Daniel Rosenberg wrote:
> This adds a case insensitive hash function to allow taking the hash
> without needing to allocate a casefolded copy of the string.

It would be helpful to add a few more details in this commit message.
Somewhat along the lines of: ->d_hash() for casefolding currently allocates
memory, it needs to use GFP_ATOMIC due to ->d_hash() being called in rcu-walk
mode, this is unreliable and inefficient, and this patch allows solving that
problem by removing the need to allocate memory.

- Eric