From patchwork Fri Aug 15 02:58:57 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: 4726131 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 C4722C0338 for ; Fri, 15 Aug 2014 03:00:07 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D939E201C8 for ; Fri, 15 Aug 2014 03:00:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E3B18201BF for ; Fri, 15 Aug 2014 03:00:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932113AbaHOC7T (ORCPT ); Thu, 14 Aug 2014 22:59:19 -0400 Received: from mail-pa0-f52.google.com ([209.85.220.52]:56606 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753135AbaHOC7Q (ORCPT ); Thu, 14 Aug 2014 22:59:16 -0400 Received: by mail-pa0-f52.google.com with SMTP id bj1so2741601pad.39 for ; Thu, 14 Aug 2014 19:59:16 -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=uRGbWdSPkujq2kbwHYyDB41Im3pmWQSD158Ar6HFUus=; b=br99nowyiU3hItw9VKrTwBPmcB+oBG9FkeiT1+nAiozkuM+Nktdzho9ikmkZPsXIZZ BgfyZEs3EbiZFs0Yv2NV8ULDuC9BbYQlAz+WFNa3/KcKmNVFEy1wjHKUdS8nlWThvS1c P5NMenRsXh+QgKSYmP2bK7QeIH72r75pYcv9zM/glS6CjvEg2qw8a0HP4kKsjrGpeCf1 Ff87Mb+egQEgdTIcfxglhHm9U02NvDfbSzzpxquUWtrO4tnj5KS0Hd8wBSE3t8j6+0LJ 52340ELH9Sw3xJQGLeUkUkk40PlKO0W9b5lcNjbnfDvpzMU1u3pnY6yyf5Ifz4mpPNfK 4TSA== X-Received: by 10.70.61.10 with SMTP id l10mr6414699pdr.154.1408071556099; Thu, 14 Aug 2014 19:59:16 -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 x10sm10052877pdp.24.2014.08.14.19.59.11 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 14 Aug 2014 19:59:14 -0700 (PDT) Received: by mcgrof@gmail.com (sSMTP sendmail emulation); Thu, 14 Aug 2014 19:59:10 -0700 From: "Luis R. Rodriguez" To: viro@zeniv.linux.org.uk, clm@fb.com, jbacik@fb.com, hch@infradead.org 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 v3 1/2] fs/super.c: add new super block sub devices super_block_dev Date: Thu, 14 Aug 2014 19:58:57 -0700 Message-Id: <1408071538-14354-2-git-send-email-mcgrof@do-not-panic.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1408071538-14354-1-git-send-email-mcgrof@do-not-panic.com> References: <1408071538-14354-1-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=-7.5 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 f0890e4..c9152ac 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1197,6 +1197,13 @@ 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 */ @@ -1221,6 +1228,7 @@ 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; @@ -1821,6 +1829,8 @@ 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 *),