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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 B1617C433E0 for ; Wed, 1 Jul 2020 06:36:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9476D20747 for ; Wed, 1 Jul 2020 06:36:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727777AbgGAGgK (ORCPT ); Wed, 1 Jul 2020 02:36:10 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:59264 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726144AbgGAGgJ (ORCPT ); Wed, 1 Jul 2020 02:36:09 -0400 Received: from DGGEMS412-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 33A915B5D58E87AE5F1F; Wed, 1 Jul 2020 14:36:04 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.212) with Microsoft SMTP Server (TLS) id 14.3.487.0; Wed, 1 Jul 2020 14:36:03 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: add symbolic link to kobject in sysfs To: Daeho Jeong , , , CC: Daeho Jeong References: <20200630005625.2405062-1-daeho43@gmail.com> From: Chao Yu Message-ID: <961072bb-4c8f-b01e-666d-1f5e35a8b76d@huawei.com> Date: Wed, 1 Jul 2020 14:36:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200630005625.2405062-1-daeho43@gmail.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Daeho, On 2020/6/30 8:56, Daeho Jeong wrote: > From: Daeho Jeong > > Added a symbolic link to directory of sysfs. It will > create a symbolic link such as "mount_0" and "mount_1" to > each f2fs mount in the order of mounting filesystem. It will > provide easy access to sysfs node even if not knowing the > specific device node name like sda19 and dm-3. Just out of curiosity, if we mount/umount as below: mount /dev/zram0 /mnt/f2fs0 mount /dev/zram1 /mnt/f2fs1 umount /mnt/f2fs0 mount /dev/zram0 /mnt/f2fs0 Shouldn't sysfs structure be: mount_2 -> zram0 mount_1 -> zram1 zram0 zram1 Then we can know zram0 is mounted after zram1? However the result shows: mount_0 -> zram0 mount_1 -> zram1 zram0 zram1 Thanks, > > Signed-off-by: Daeho Jeong > --- > fs/f2fs/f2fs.h | 4 ++++ > fs/f2fs/sysfs.c | 31 +++++++++++++++++++++++++++---- > 2 files changed, 31 insertions(+), 4 deletions(-) > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index 4b28fd42fdbc..7d6c5f8ce16b 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -1419,6 +1419,8 @@ struct decompress_io_ctx { > #define MAX_COMPRESS_LOG_SIZE 8 > #define MAX_COMPRESS_WINDOW_SIZE ((PAGE_SIZE) << MAX_COMPRESS_LOG_SIZE) > > +#define MOUNT_NAME_SIZE 20 > + > struct f2fs_sb_info { > struct super_block *sb; /* pointer to VFS super block */ > struct proc_dir_entry *s_proc; /* proc entry */ > @@ -1599,6 +1601,8 @@ struct f2fs_sb_info { > /* For sysfs suppport */ > struct kobject s_kobj; > struct completion s_kobj_unregister; > + int s_mount_id; > + char s_mount_name[MOUNT_NAME_SIZE]; > > /* For shrinker support */ > struct list_head s_list; > diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c > index ab40e1f89f23..64bbe0b3b830 100644 > --- a/fs/f2fs/sysfs.c > +++ b/fs/f2fs/sysfs.c > @@ -18,6 +18,7 @@ > #include > > static struct proc_dir_entry *f2fs_proc_root; > +static struct ida f2fs_mount_ida; > > /* Sysfs support for f2fs */ > enum { > @@ -906,6 +907,9 @@ int __init f2fs_init_sysfs(void) > } else { > f2fs_proc_root = proc_mkdir("fs/f2fs", NULL); > } > + > + ida_init(&f2fs_mount_ida); > + > return ret; > } > > @@ -915,6 +919,7 @@ void f2fs_exit_sysfs(void) > kset_unregister(&f2fs_kset); > remove_proc_entry("fs/f2fs", NULL); > f2fs_proc_root = NULL; > + ida_destroy(&f2fs_mount_ida); > } > > int f2fs_register_sysfs(struct f2fs_sb_info *sbi) > @@ -926,12 +931,22 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi) > init_completion(&sbi->s_kobj_unregister); > err = kobject_init_and_add(&sbi->s_kobj, &f2fs_sb_ktype, NULL, > "%s", sb->s_id); > - if (err) { > - kobject_put(&sbi->s_kobj); > - wait_for_completion(&sbi->s_kobj_unregister); > - return err; > + if (err) > + goto err1; > + > + sbi->s_mount_id = ida_simple_get(&f2fs_mount_ida, 0, 0, GFP_KERNEL); > + if (sbi->s_mount_id < 0) { > + err = sbi->s_mount_id; > + goto err1; > } > > + snprintf(sbi->s_mount_name, MOUNT_NAME_SIZE, "mount_%d", > + sbi->s_mount_id); > + err = sysfs_create_link(&f2fs_kset.kobj, &sbi->s_kobj, > + sbi->s_mount_name); > + if (err) > + goto err2; > + > if (f2fs_proc_root) > sbi->s_proc = proc_mkdir(sb->s_id, f2fs_proc_root); > > @@ -946,6 +961,12 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi) > victim_bits_seq_show, sb); > } > return 0; > +err2: > + ida_simple_remove(&f2fs_mount_ida, sbi->s_mount_id); > +err1: > + kobject_put(&sbi->s_kobj); > + wait_for_completion(&sbi->s_kobj_unregister); > + return err; > } > > void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi) > @@ -957,6 +978,8 @@ void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi) > remove_proc_entry("victim_bits", sbi->s_proc); > remove_proc_entry(sbi->sb->s_id, f2fs_proc_root); > } > + sysfs_remove_link(&f2fs_kset.kobj, sbi->s_mount_name); > + ida_simple_remove(&f2fs_mount_ida, sbi->s_mount_id); > kobject_del(&sbi->s_kobj); > kobject_put(&sbi->s_kobj); > } >