From patchwork Tue Mar 22 22:27:37 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gabriel Krisman Bertazi X-Patchwork-Id: 12789328 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8E70C433EF for ; Tue, 22 Mar 2022 22:27:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4B7B36B0085; Tue, 22 Mar 2022 18:27:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 43EBC6B0089; Tue, 22 Mar 2022 18:27:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2E0F16B008A; Tue, 22 Mar 2022 18:27:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0190.hostedemail.com [216.40.44.190]) by kanga.kvack.org (Postfix) with ESMTP id 1F7A26B0085 for ; Tue, 22 Mar 2022 18:27:56 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id D5BEBA5658 for ; Tue, 22 Mar 2022 22:27:55 +0000 (UTC) X-FDA: 79273460910.16.77708B8 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) by imf21.hostedemail.com (Postfix) with ESMTP id F3C7E1C001B for ; Tue, 22 Mar 2022 22:27:54 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: krisman) with ESMTPSA id D9C951F442B1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1647988074; bh=YxlD4pKbjYfFieAPsszS75Zdc2phBkHyCnybdtTEx1A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C+XC9cAyTOUV0cCdI9gkhq6QEENUGA7UY36fUmvw+CIl2lr7Qj6JJYE2NXLKmj5Eb 0CU2Xem+OkOL53lB67VnRwu6ZnyhBhw+p88EBAC2tpgegisxHD3E1ZEiEUnQA38pkd gXdZZP7orn0Kcrbdj5e4S9Dl3TjmaEaUD4bbbqHUdKGHurgmKFZ9L0p/Upr1gw7hwg XIohw2PPfoXBw0wb3WtBNKXIdY+jOpzMi+jUrJBDmJx/2tptfEHAUY8IzhmnF5M389 E5rDecQpUeu3fKsXgOdxXd3irzqDY6sDT74YKgGzq3idx727I0ZlvOrZE2v6Um0W1b Ftx0gHGNTvwkQ== From: Gabriel Krisman Bertazi To: hughd@google.com, akpm@linux-foundation.org, amir73il@gmail.com Cc: khazhy@google.com, linux-mm@kvack.org, Gabriel Krisman Bertazi , kernel@collabora.com Subject: [PATCH 2/3] shmem: Introduce /sys/fs/tmpfs support Date: Tue, 22 Mar 2022 18:27:37 -0400 Message-Id: <20220322222738.182974-3-krisman@collabora.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220322222738.182974-1-krisman@collabora.com> References: <20220322222738.182974-1-krisman@collabora.com> MIME-Version: 1.0 X-Stat-Signature: 43addzc7f8tcd87hgaa17arw8jun9cng X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: F3C7E1C001B Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=collabora.com header.s=mail header.b=C+XC9cAy; dmarc=pass (policy=none) header.from=collabora.com; spf=pass (imf21.hostedemail.com: domain of krisman@collabora.com designates 46.235.227.227 as permitted sender) smtp.mailfrom=krisman@collabora.com X-Rspam-User: X-HE-Tag: 1647988074-867956 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In order to expose tmpfs statistics on sysfs, add the boilerplate code to create the /sys/fs/tmpfs structure. Other filesystems usually do /sys/fs//, but since this is a nodev filesystem, I'm proposing to use fsid as . This takes care of not exposing SB_NOUSER mounts. I don't think we have a usecase for showing them and, since they don't appear elsewhere, they might be confusing to users. Signed-off-by: Gabriel Krisman Bertazi --- include/linux/shmem_fs.h | 4 +++ mm/shmem.c | 73 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 76 insertions(+), 1 deletion(-) diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index 1a7cd9ea9107..c27ecf0e1b3b 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -47,6 +47,10 @@ struct shmem_sb_info { unsigned long acct_errors; unsigned long space_errors; + + /* sysfs */ + struct kobject s_kobj; /* /sys/fs/tmpfs/ */ + struct completion s_kobj_unregister; }; static inline struct shmem_inode_info *SHMEM_I(struct inode *inode) diff --git a/mm/shmem.c b/mm/shmem.c index c350fa0a0fff..5e8973664b7f 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -250,6 +250,7 @@ static const struct inode_operations shmem_dir_inode_operations; static const struct inode_operations shmem_special_inode_operations; static const struct vm_operations_struct shmem_vm_ops; static struct file_system_type shmem_fs_type; +static struct kobject *shmem_root; bool vma_is_shmem(struct vm_area_struct *vma) { @@ -3584,6 +3585,57 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root) #endif /* CONFIG_TMPFS */ +#if defined(CONFIG_TMPFS) && defined(CONFIG_SYSFS) +#define TMPFS_SB_ATTR_RO(name) \ + static struct kobj_attribute tmpfs_sb_attr_##name = __ATTR_RO(name) + +static struct attribute *tmpfs_attrs[] = { + NULL +}; +ATTRIBUTE_GROUPS(tmpfs); + +static void tmpfs_sb_release(struct kobject *kobj) +{ + struct shmem_sb_info *sbinfo = + container_of(kobj, struct shmem_sb_info, s_kobj); + + complete(&sbinfo->s_kobj_unregister); +} + +static struct kobj_type tmpfs_sb_ktype = { + .default_groups = tmpfs_groups, + .sysfs_ops = &kobj_sysfs_ops, + .release = tmpfs_sb_release, +}; + +static void shmem_unregister_sysfs(struct super_block *sb) +{ + struct shmem_sb_info *sbinfo = SHMEM_SB(sb); + + kobject_del(&sbinfo->s_kobj); + kobject_put(&sbinfo->s_kobj); + wait_for_completion(&sbinfo->s_kobj_unregister); +} + +static int shmem_register_sysfs(struct super_block *sb) +{ + int err; + struct shmem_sb_info *sbinfo = SHMEM_SB(sb); + __kernel_fsid_t fsid = uuid_to_fsid(sb->s_uuid.b); + + init_completion(&sbinfo->s_kobj_unregister); + err = kobject_init_and_add(&sbinfo->s_kobj, &tmpfs_sb_ktype, shmem_root, + "%x%x", fsid.val[0], fsid.val[1]); + if (err) { + kobject_put(&sbinfo->s_kobj); + wait_for_completion(&sbinfo->s_kobj_unregister); + return err; + } + + return 0; +} +#endif /* CONFIG_TMPFS && CONFIG_SYSFS */ + static void shmem_put_super(struct super_block *sb) { struct shmem_sb_info *sbinfo = SHMEM_SB(sb); @@ -3591,6 +3643,12 @@ static void shmem_put_super(struct super_block *sb) free_percpu(sbinfo->ino_batch); percpu_counter_destroy(&sbinfo->used_blocks); mpol_put(sbinfo->mpol); + +#if IS_ENABLED(CONFIG_TMPFS) && IS_ENABLED(CONFIG_SYSFS) + if (!(sb->s_flags & SB_NOUSER)) + shmem_unregister_sysfs(sb); +#endif + kfree(sbinfo); sb->s_fs_info = NULL; } @@ -3673,6 +3731,13 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_root = d_make_root(inode); if (!sb->s_root) goto failed; + +#if IS_ENABLED(CONFIG_TMPFS) && IS_ENABLED(CONFIG_SYSFS) + if (!(sb->s_flags & SB_NOUSER)) + if (shmem_register_sysfs(sb)) + goto failed; +#endif + return 0; failed: @@ -3889,11 +3954,15 @@ int __init shmem_init(void) goto out2; } + shmem_root = kobject_create_and_add("tmpfs", fs_kobj); + if (!shmem_root) + goto out1; + shm_mnt = kern_mount(&shmem_fs_type); if (IS_ERR(shm_mnt)) { error = PTR_ERR(shm_mnt); pr_err("Could not kern_mount tmpfs\n"); - goto out1; + goto put_kobj; } #ifdef CONFIG_TRANSPARENT_HUGEPAGE @@ -3904,6 +3973,8 @@ int __init shmem_init(void) #endif return 0; +put_kobj: + kobject_put(shmem_root); out1: unregister_filesystem(&shmem_fs_type); out2: