From patchwork Wed Aug 2 15:41:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 13338478 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 330C5C05052 for ; Wed, 2 Aug 2023 15:42:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235229AbjHBPmJ (ORCPT ); Wed, 2 Aug 2023 11:42:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234722AbjHBPlz (ORCPT ); Wed, 2 Aug 2023 11:41:55 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84E1F127; Wed, 2 Aug 2023 08:41:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=t+hutzNu+OLKs7hwR5oQScZRP7h/WIsttBs8nagY2hw=; b=MfqT8apVrXwKetoTs/uxlt7j0i F/hdDE9Szgwzy89HXkA2LaUSRquS53mI7cSS5sNi2T+7nVXkXcwAUpiTMNP2N9BUQzVtxjNbyk/V+ qCBQeB2jWHyLGb9su722CpdyYmQflH0nge+RxWa/9QyBGSzuoZc82mvpQI/HsRPkkYBzgHu8k5itH I7+ZnGg1fmJX0esEcvXm687uZ0D6tg3KVz8hVG+2M/YO7ONoljrafnhwMRZz+5DIsDtvInnEt0dKc uhlmNE+HbPUosHqoiBEc789L7N+kHRFooos+y6ZmJd4JNk/BCKWXPcJIKPM+Rgb0VWyHQRMGW4EdW SAC0HevA==; Received: from 2a02-8389-2341-5b80-39d3-4735-9a3c-88d8.cable.dynamic.v6.surfer.at ([2a02:8389:2341:5b80:39d3:4735:9a3c:88d8] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qRDyt-005GFa-13; Wed, 02 Aug 2023 15:41:47 +0000 From: Christoph Hellwig To: Al Viro , Christian Brauner Cc: Jan Kara , Chris Mason , Josef Bacik , David Sterba , "Theodore Ts'o" , Andreas Dilger , Jaegeuk Kim , Chao Yu , Ryusuke Konishi , "Darrick J. Wong" , Jens Axboe , linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-block@vger.kernel.org Subject: [PATCH 04/12] btrfs: open block devices after superblock creation Date: Wed, 2 Aug 2023 17:41:23 +0200 Message-Id: <20230802154131.2221419-5-hch@lst.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230802154131.2221419-1-hch@lst.de> References: <20230802154131.2221419-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Currently btrfs_mount_root opens the block devices before committing to allocating a super block. That creates problems for restricting the number of writers to a device, and also leads to a unusual and not very helpful holder (the fs_type). Reorganize the code to first look whether the superblock for a particular fsid does already exist and open the block devices only if it doesn't, mirror the recent changes to the VFS mount helpers. Signed-off-by: Christoph Hellwig --- fs/btrfs/super.c | 51 ++++++++++++++++++++++------------------------ fs/btrfs/volumes.c | 4 ++-- 2 files changed, 26 insertions(+), 29 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index b318bddefd5236..5980b5dcc6b163 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1434,10 +1434,8 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid, static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, int flags, const char *device_name, void *data) { - struct block_device *bdev = NULL; struct super_block *s; struct btrfs_device *device = NULL; - struct btrfs_fs_devices *fs_devices = NULL; struct btrfs_fs_info *fs_info = NULL; void *new_sec_opts = NULL; int error = 0; @@ -1483,35 +1481,36 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, error = PTR_ERR(device); goto error_fs_info; } - - fs_devices = device->fs_devices; - fs_info->fs_devices = fs_devices; - - error = btrfs_open_devices(fs_devices, sb_open_mode(flags), fs_type); + fs_info->fs_devices = device->fs_devices; mutex_unlock(&uuid_mutex); - if (error) - goto error_fs_info; - - if (!(flags & SB_RDONLY) && fs_devices->rw_devices == 0) { - error = -EACCES; - goto error_close_devices; - } - bdev = fs_devices->latest_dev->bdev; s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | SB_NOSEC, fs_info); if (IS_ERR(s)) { error = PTR_ERR(s); - goto error_close_devices; + goto error_fs_info; } if (s->s_root) { - btrfs_close_devices(fs_devices); btrfs_free_fs_info(fs_info); if ((flags ^ s->s_flags) & SB_RDONLY) error = -EBUSY; } else { - snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev); + struct btrfs_fs_devices *fs_devices = fs_info->fs_devices; + + error = btrfs_open_devices(fs_devices, sb_open_mode(flags), + fs_type); + if (error) + goto out_deactivate; + + if (!(flags & SB_RDONLY) && fs_devices->rw_devices == 0) { + error = -EACCES; + btrfs_close_devices(fs_info->fs_devices); + goto out_deactivate; + } + + snprintf(s->s_id, sizeof(s->s_id), "%pg", + fs_devices->latest_dev->bdev); shrinker_debugfs_rename(&s->s_shrink, "sb-%s:%s", fs_type->name, s->s_id); btrfs_sb(s)->bdev_holder = fs_type; @@ -1519,21 +1518,19 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type, } if (!error) error = security_sb_set_mnt_opts(s, new_sec_opts, 0, NULL); + if (error) + goto out_deactivate; security_free_mnt_opts(&new_sec_opts); - if (error) { - deactivate_locked_super(s); - return ERR_PTR(error); - } - return dget(s->s_root); -error_close_devices: - btrfs_close_devices(fs_devices); -error_fs_info: - btrfs_free_fs_info(fs_info); +out_deactivate: + deactivate_locked_super(s); error_sec_opts: security_free_mnt_opts(&new_sec_opts); return ERR_PTR(error); +error_fs_info: + btrfs_free_fs_info(fs_info); + goto error_sec_opts; } /* diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 8246578c70f55b..88e9daae5e74ed 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1269,7 +1269,6 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, { int ret; - lockdep_assert_held(&uuid_mutex); /* * The device_list_mutex cannot be taken here in case opening the * underlying device takes further locks like open_mutex. @@ -1277,7 +1276,7 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, * We also don't need the lock here as this is called during mount and * exclusion is provided by uuid_mutex */ - + mutex_lock(&uuid_mutex); if (fs_devices->opened) { fs_devices->opened++; ret = 0; @@ -1285,6 +1284,7 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, list_sort(NULL, &fs_devices->devices, devid_cmp); ret = open_fs_devices(fs_devices, flags, holder); } + mutex_unlock(&uuid_mutex); return ret; }