From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64491C2BA2B for ; Mon, 13 Apr 2020 17:50:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 519B2206DA for ; Mon, 13 Apr 2020 17:50:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387451AbgDMRu0 (ORCPT ); Mon, 13 Apr 2020 13:50:26 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:33100 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387436AbgDMRuZ (ORCPT ); Mon, 13 Apr 2020 13:50:25 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: ezequiel) with ESMTPSA id 797372A0A5B Message-ID: <2672d7de2033fa14b9835b17b6fc59ba2cc4cd14.camel@collabora.com> Subject: Re: [PATCH v2] unicode: Expose available encodings in sysfs From: Ezequiel Garcia To: Gabriel Krisman Bertazi , linux-fsdevel@vger.kernel.org Cc: linux-ext4@vger.kernel.org, kernel@collabora.com, Theodore Ts'o , Jaegeuk Kim Date: Mon, 13 Apr 2020 14:50:13 -0300 In-Reply-To: <20200413165352.598877-1-krisman@collabora.com> References: <20200413165352.598877-1-krisman@collabora.com> Organization: Collabora Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.0-1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hey Gabriel, On Mon, 2020-04-13 at 12:53 -0400, Gabriel Krisman Bertazi wrote: > A filesystem configuration utility has no way to detect which filename > encodings are supported by the running kernel. This means, for > instance, mkfs has no way to tell if the generated filesystem will be > mountable in the current kernel or not. Also, users have no easy way to > know if they can update the encoding in their filesystems and still have > something functional in the end. > > This exposes details of the encodings available in the unicode > subsystem, to fill that gap. > > Cc: Theodore Ts'o > Cc: Jaegeuk Kim > Signed-off-by: Gabriel Krisman Bertazi > > --- > Changes since v1: > - Make init functions static. (lkp) > > Documentation/ABI/testing/sysfs-fs-unicode | 13 +++++ > fs/unicode/utf8-core.c | 64 ++++++++++++++++++++++ > fs/unicode/utf8-norm.c | 18 ++++++ > fs/unicode/utf8n.h | 5 ++ > 4 files changed, 100 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-fs-unicode > > diff --git a/Documentation/ABI/testing/sysfs-fs-unicode b/Documentation/ABI/testing/sysfs-fs-unicode > new file mode 100644 > index 000000000000..15c63367bb8e > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-fs-unicode > @@ -0,0 +1,13 @@ > +What: /sys/fs/unicode/latest > +Date: April 2020 > +Contact: Gabriel Krisman Bertazi > +Description: > + The latest version of the Unicode Standard supported by > + this kernel > + Missing stop at the end of the sentence? > +What: /sys/fs/unicode/encodings > +Date: April 2020 > +Contact: Gabriel Krisman Bertazi > +Description: > + List of encodings and corresponding versions supported > + by this kernel Ditto. > diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c > index 2a878b739115..b48e13e823a5 100644 > --- a/fs/unicode/utf8-core.c > +++ b/fs/unicode/utf8-core.c > @@ -6,6 +6,7 @@ > #include > #include > #include > +#include > > #include "utf8n.h" > > @@ -212,4 +213,67 @@ void utf8_unload(struct unicode_map *um) > } > EXPORT_SYMBOL(utf8_unload); > > +static ssize_t latest_show(struct kobject *kobj, > + struct kobj_attribute *attr, char *buf) > +{ > + int l = utf8version_latest(); > + > + return snprintf(buf, PAGE_SIZE, "UTF-8 %d.%d.%d\n", UNICODE_AGE_MAJ(l), > + UNICODE_AGE_MIN(l), UNICODE_AGE_REV(l)); > + > +} > +static ssize_t encodings_show(struct kobject *kobj, > + struct kobj_attribute *attr, char *buf) > +{ > + int n; > + > + n = snprintf(buf, PAGE_SIZE, "UTF-8:"); > + n += utf8version_list(buf + n, PAGE_SIZE - n); > + n += snprintf(buf+n, PAGE_SIZE-n, "\n"); > + I was wondering how sysfs-compliant this was, in terms of one value per attribute. Although, we do seem to break this on a few cases. > + return n; > +} > + > +#define UCD_ATTR(x) \ > + static struct kobj_attribute x ## _attr = __ATTR_RO(x) > + > +UCD_ATTR(latest); > +UCD_ATTR(encodings); > + > +static struct attribute *ucd_attrs[] = { > + &latest_attr.attr, > + &encodings_attr.attr, > + NULL, > +}; > +static const struct attribute_group ucd_attr_group = { > + .attrs = ucd_attrs, > +}; > +static struct kobject *ucd_root; > + > +static int __init ucd_init(void) > +{ > + int ret; > + > + ucd_root = kobject_create_and_add("unicode", fs_kobj); > + if (!ucd_root) > + return -ENOMEM; > + > + ret = sysfs_create_group(ucd_root, &ucd_attr_group); > + if (ret) { > + kobject_put(ucd_root); > + ucd_root = NULL; > + return ret; > + } > + > + return 0; > +} > + > +static void __exit ucd_exit(void) > +{ > + kobject_put(ucd_root); > +} > + > +module_init(ucd_init); This code is not a module, so how about fs_initcall? > +module_exit(ucd_exit) > + I can be wrong, but I see no way to remove it :-) Thanks, Ezequiel