From patchwork Wed Jul 16 21:37:57 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Luis R. Rodriguez" X-Patchwork-Id: 4571451 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 74A2BC0514 for ; Wed, 16 Jul 2014 21:38:30 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 90CF72008F for ; Wed, 16 Jul 2014 21:38:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 88E24201B9 for ; Wed, 16 Jul 2014 21:38:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754363AbaGPViO (ORCPT ); Wed, 16 Jul 2014 17:38:14 -0400 Received: from mail-pa0-f53.google.com ([209.85.220.53]:55713 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752579AbaGPViL (ORCPT ); Wed, 16 Jul 2014 17:38:11 -0400 Received: by mail-pa0-f53.google.com with SMTP id kq14so1997440pab.26 for ; Wed, 16 Jul 2014 14:38:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=Ls7OT7NHuOhyE2jDvTXrx/84OpmFXHcJ6tNiII5rndo=; b=hExKGRx5B+grQoGP6ECGP390gFj9XH2CkkzROyhGx7mCNwetp2qOGErNK/OOKQ+qik UEKCWW7MUQryp/xRnNrp6o/hCS3fbUjc65UxBdmu0qWtpL1WepiGHIAqpuXjPm0q6DWX DorC+VOr+GjYFiyVDGciR4kC/sChPtJ/47fVC2eyzeiMKN4eTOVcoqr77aHHg/DLO3Xu WBPXLv+vNs5nyxLTtR+47yrzTt/K8RqkBWJlGv3xVoZRauIKwgwbilhS2KzL/c90muUA cmzK35CLJU11Sl/FJQtonUI8RRyX/eI9+cXKtYv1UdcWaqNpH5pleF719Lh67bh111sy EPFw== X-Received: by 10.66.196.168 with SMTP id in8mr18950283pac.102.1405546690932; Wed, 16 Jul 2014 14:38:10 -0700 (PDT) Received: from mcgrof@gmail.com (c-98-234-145-61.hsd1.ca.comcast.net. [98.234.145.61]) by mx.google.com with ESMTPSA id y3sm517210pdy.27.2014.07.16.14.38.07 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 16 Jul 2014 14:38:09 -0700 (PDT) Received: by mcgrof@gmail.com (sSMTP sendmail emulation); Wed, 16 Jul 2014 14:38:06 -0700 From: "Luis R. Rodriguez" To: viro@zeniv.linux.org.uk, clm@fb.com, jbacik@fb.com Cc: linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, jeffm@suse.com, fdmanana@suse.com, "Luis R. Rodriguez" Subject: [RFC v2 1/2] fs/super.c: add new super block sub devices super_block_dev Date: Wed, 16 Jul 2014 14:37:57 -0700 Message-Id: <1405546678-7846-2-git-send-email-mcgrof@do-not-panic.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1405546678-7846-1-git-send-email-mcgrof@do-not-panic.com> References: <1405546678-7846-1-git-send-email-mcgrof@do-not-panic.com> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: "Luis R. Rodriguez" Modern filesystems are using the get_anon_bdev() for internal notions of volumes, snapshots for a single super block but never exposing them directly to the VFS layer. While this works its leaves the VFS layer growing dumb over what filesystems are doing. This creates a new super block subdevice which we can use to start stuffing in information about the underlying bdev's and its associated super block to start off with. This at least now lets us implement proper support for ustat() once filesystems are modified to use this data structure and respective helpers. Signed-off-by: Luis R. Rodriguez --- fs/super.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++-- include/linux/fs.h | 10 ++++++++ 2 files changed, 76 insertions(+), 2 deletions(-) diff --git a/fs/super.c b/fs/super.c index d20d5b1..d871892 100644 --- a/fs/super.c +++ b/fs/super.c @@ -133,6 +133,68 @@ static unsigned long super_cache_count(struct shrinker *shrink, return total_objects; } +static bool super_dev_match(struct super_block *sb, dev_t dev) +{ + struct super_block_dev *sbdev; + + if (sb->s_dev == dev) + return true; + + if (list_empty(&sb->s_sbdevs)) + return false; + + list_for_each_entry(sbdev, &sb->s_sbdevs, entry) + if (sbdev->anon_dev == dev) + return true; + + return false; +} + +int insert_anon_sbdev(struct super_block *sb, struct super_block_dev *sbdev) +{ + int ret; + + ret = get_anon_bdev(&sbdev->anon_dev); + if (ret) + return ret; + + sbdev->sb = sb; + + spin_lock(&sb_lock); + list_add_tail(&sbdev->entry, &sb->s_sbdevs); + spin_unlock(&sb_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(insert_anon_sbdev); + +void remove_anon_sbdev(struct super_block_dev *sbdev) +{ + struct super_block *sb; + struct super_block_dev *sbdev_i, *tmp; + + if (!sbdev) + return; + + sb = sbdev->sb; + + spin_lock(&sb_lock); + + WARN_ON(list_empty(&sb->s_sbdevs)); + + list_for_each_entry_safe(sbdev_i, tmp, &sb->s_sbdevs, entry) { + if (sbdev == sbdev_i) { + list_del_init(&sbdev_i->entry); + break; + } + } + + spin_unlock(&sb_lock); + + free_anon_bdev(sbdev->anon_dev); +} +EXPORT_SYMBOL_GPL(remove_anon_sbdev); + /** * destroy_super - frees a superblock * @s: superblock to free @@ -148,6 +210,7 @@ static void destroy_super(struct super_block *s) percpu_counter_destroy(&s->s_writers.counter[i]); security_sb_free(s); WARN_ON(!list_empty(&s->s_mounts)); + WARN_ON(!list_empty(&s->s_sbdevs)); kfree(s->s_subtype); kfree(s->s_options); kfree_rcu(s, rcu); @@ -188,6 +251,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags) INIT_HLIST_NODE(&s->s_instances); INIT_HLIST_BL_HEAD(&s->s_anon); INIT_LIST_HEAD(&s->s_inodes); + INIT_LIST_HEAD(&s->s_sbdevs); if (list_lru_init(&s->s_dentry_lru)) goto fail; @@ -652,7 +716,7 @@ restart: spin_unlock(&sb_lock); return NULL; } - + struct super_block *user_get_super(dev_t dev) { struct super_block *sb; @@ -662,7 +726,7 @@ rescan: list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; - if (sb->s_dev == dev) { + if (super_dev_match(sb, dev)) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); diff --git a/include/linux/fs.h b/include/linux/fs.h index e11d60c..f97b559 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1172,6 +1172,13 @@ struct sb_writers { #endif }; +/* we can expand this to help the VFS layer with modern filesystems */ +struct super_block_dev { + struct super_block *sb; + struct list_head entry; /* For struct sb->s_sbdevs */ + dev_t anon_dev; +}; + struct super_block { struct list_head s_list; /* Keep this first */ dev_t s_dev; /* search index; _not_ kdev_t */ @@ -1196,6 +1203,7 @@ struct super_block { struct list_head s_inodes; /* all inodes */ struct hlist_bl_head s_anon; /* anonymous dentries for (nfs) exporting */ + struct list_head s_sbdevs; /* internal fs dev_t */ struct list_head s_mounts; /* list of mounts; _not_ for fs use */ struct block_device *s_bdev; struct backing_dev_info *s_bdi; @@ -1796,6 +1804,8 @@ void deactivate_locked_super(struct super_block *sb); int set_anon_super(struct super_block *s, void *data); int get_anon_bdev(dev_t *); void free_anon_bdev(dev_t); +int insert_anon_sbdev(struct super_block *sb, struct super_block_dev *sbdev); +void remove_anon_sbdev(struct super_block_dev *sbdev); struct super_block *sget(struct file_system_type *type, int (*test)(struct super_block *,void *), int (*set)(struct super_block *,void *),