From patchwork Wed Nov 29 23:23:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Chamberlain X-Patchwork-Id: 10083871 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4FA0A60234 for ; Wed, 29 Nov 2017 23:27:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4239429D52 for ; Wed, 29 Nov 2017 23:27:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 36CBB29D57; Wed, 29 Nov 2017 23:27:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9F5E5283D9 for ; Wed, 29 Nov 2017 23:27:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753052AbdK2XYF (ORCPT ); Wed, 29 Nov 2017 18:24:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:53864 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752815AbdK2XYC (ORCPT ); Wed, 29 Nov 2017 18:24:02 -0500 Received: from garbanzo.do-not-panic.com (c-73-15-241-2.hsd1.ca.comcast.net [73.15.241.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 979D921986; Wed, 29 Nov 2017 23:24:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 979D921986 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=mcgrof@kernel.org From: "Luis R. Rodriguez" To: viro@zeniv.linux.org.uk, bart.vanassche@wdc.com, ming.lei@redhat.com, tytso@mit.edu, darrick.wong@oracle.com, jikos@kernel.org, rjw@rjwysocki.net, pavel@ucw.cz, len.brown@intel.com, linux-fsdevel@vger.kernel.org Cc: boris.ostrovsky@oracle.com, jgross@suse.com, todd.e.brandt@linux.intel.com, nborisov@suse.com, jack@suse.cz, martin.petersen@oracle.com, ONeukum@suse.com, oleksandr@natalenko.name, oleg.b.antonyan@gmail.com, yu.chen.surf@gmail.com, dan.j.williams@intel.com, linux-pm@vger.kernel.org, linux-block@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, "Luis R. Rodriguez" Subject: [PATCH 01/11] fs: provide unlocked helper for freeze_super() Date: Wed, 29 Nov 2017 15:23:46 -0800 Message-Id: <20171129232356.28296-2-mcgrof@kernel.org> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20171129232356.28296-1-mcgrof@kernel.org> References: <20171129232356.28296-1-mcgrof@kernel.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP freeze_super() holds a write lock, however we wish to also enable callers which already hold the write lock. To do this provide a helper and make freeze_super() use it. This way, all that freeze_super() does now is lock handling and active count management. This change has no functional changes. Suggested-by: Dave Chinner Signed-off-by: Luis R. Rodriguez Reviewed-by: Jan Kara --- fs/super.c | 100 +++++++++++++++++++++++++++++++++---------------------------- 1 file changed, 55 insertions(+), 45 deletions(-) diff --git a/fs/super.c b/fs/super.c index d4e33e8f1e6f..a7650ff22f0e 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1387,59 +1387,20 @@ static void sb_freeze_unlock(struct super_block *sb) percpu_up_write(sb->s_writers.rw_sem + level); } -/** - * freeze_super - lock the filesystem and force it into a consistent state - * @sb: the super to lock - * - * Syncs the super to make sure the filesystem is consistent and calls the fs's - * freeze_fs. Subsequent calls to this without first thawing the fs will return - * -EBUSY. - * - * During this function, sb->s_writers.frozen goes through these values: - * - * SB_UNFROZEN: File system is normal, all writes progress as usual. - * - * SB_FREEZE_WRITE: The file system is in the process of being frozen. New - * writes should be blocked, though page faults are still allowed. We wait for - * all writes to complete and then proceed to the next stage. - * - * SB_FREEZE_PAGEFAULT: Freezing continues. Now also page faults are blocked - * but internal fs threads can still modify the filesystem (although they - * should not dirty new pages or inodes), writeback can run etc. After waiting - * for all running page faults we sync the filesystem which will clean all - * dirty pages and inodes (no new dirty pages or inodes can be created when - * sync is running). - * - * SB_FREEZE_FS: The file system is frozen. Now all internal sources of fs - * modification are blocked (e.g. XFS preallocation truncation on inode - * reclaim). This is usually implemented by blocking new transactions for - * filesystems that have them and need this additional guard. After all - * internal writers are finished we call ->freeze_fs() to finish filesystem - * freezing. Then we transition to SB_FREEZE_COMPLETE state. This state is - * mostly auxiliary for filesystems to verify they do not modify frozen fs. - * - * sb->s_writers.frozen is protected by sb->s_umount. - */ -int freeze_super(struct super_block *sb) +/* Caller takes lock and handles active count */ +static int freeze_locked_super(struct super_block *sb) { int ret; - atomic_inc(&sb->s_active); - down_write(&sb->s_umount); - if (sb->s_writers.frozen != SB_UNFROZEN) { - deactivate_locked_super(sb); + if (sb->s_writers.frozen != SB_UNFROZEN) return -EBUSY; - } - if (!(sb->s_flags & SB_BORN)) { - up_write(&sb->s_umount); + if (!(sb->s_flags & SB_BORN)) return 0; /* sic - it's "nothing to do" */ - } if (sb_rdonly(sb)) { /* Nothing to do really... */ sb->s_writers.frozen = SB_FREEZE_COMPLETE; - up_write(&sb->s_umount); return 0; } @@ -1468,7 +1429,6 @@ int freeze_super(struct super_block *sb) sb->s_writers.frozen = SB_UNFROZEN; sb_freeze_unlock(sb); wake_up(&sb->s_writers.wait_unfrozen); - deactivate_locked_super(sb); return ret; } } @@ -1478,9 +1438,59 @@ int freeze_super(struct super_block *sb) */ sb->s_writers.frozen = SB_FREEZE_COMPLETE; lockdep_sb_freeze_release(sb); - up_write(&sb->s_umount); return 0; } + +/** + * freeze_super - lock the filesystem and force it into a consistent state + * @sb: the super to lock + * + * Syncs the super to make sure the filesystem is consistent and calls the fs's + * freeze_fs. Subsequent calls to this without first thawing the fs will return + * -EBUSY. + * + * During this function, sb->s_writers.frozen goes through these values: + * + * SB_UNFROZEN: File system is normal, all writes progress as usual. + * + * SB_FREEZE_WRITE: The file system is in the process of being frozen. New + * writes should be blocked, though page faults are still allowed. We wait for + * all writes to complete and then proceed to the next stage. + * + * SB_FREEZE_PAGEFAULT: Freezing continues. Now also page faults are blocked + * but internal fs threads can still modify the filesystem (although they + * should not dirty new pages or inodes), writeback can run etc. After waiting + * for all running page faults we sync the filesystem which will clean all + * dirty pages and inodes (no new dirty pages or inodes can be created when + * sync is running). + * + * SB_FREEZE_FS: The file system is frozen. Now all internal sources of fs + * modification are blocked (e.g. XFS preallocation truncation on inode + * reclaim). This is usually implemented by blocking new transactions for + * filesystems that have them and need this additional guard. After all + * internal writers are finished we call ->freeze_fs() to finish filesystem + * freezing. Then we transition to SB_FREEZE_COMPLETE state. This state is + * mostly auxiliary for filesystems to verify they do not modify frozen fs. + * + * sb->s_writers.frozen is protected by sb->s_umount. + */ +int freeze_super(struct super_block *sb) +{ + int error; + + atomic_inc(&sb->s_active); + + down_write(&sb->s_umount); + error = freeze_locked_super(sb); + if (error) { + deactivate_locked_super(sb); + goto out; + } + up_write(&sb->s_umount); + +out: + return error; +} EXPORT_SYMBOL(freeze_super); /**