From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([222.73.24.84]:23518 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751956AbaAFB5p (ORCPT ); Sun, 5 Jan 2014 20:57:45 -0500 Received: from fnstmail02.fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id s061vfHN002425 for ; Mon, 6 Jan 2014 09:57:43 +0800 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH v3 1/9] btrfs: Add "barrier" option to support "-o remount,barrier" Date: Mon, 6 Jan 2014 09:58:25 +0800 Message-Id: <1388973513-11240-2-git-send-email-quwenruo@cn.fujitsu.com> In-Reply-To: <1388973513-11240-1-git-send-email-quwenruo@cn.fujitsu.com> References: <1388973513-11240-1-git-send-email-quwenruo@cn.fujitsu.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Btrfs can be remounted without barrier, but there is no "barrier" option so nobody can remount btrfs back with barrier on. Only umount and mount again can re-enable barrier.(Quite awkward) Also the mount options in the document is also changed slightly for the further pairing options changes. Reported-by: Daniel Blueman Signed-off-by: Qu Wenruo Signed-off-by: Mike Fleetwood Reviewed-by: David Sterba --- Changelog: v1: Add barrier option v2: Document style change v3: Small description change --- Documentation/filesystems/btrfs.txt | 13 +++++++------ fs/btrfs/super.c | 8 +++++++- 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt index 5dd282d..ce487a2 100644 --- a/Documentation/filesystems/btrfs.txt +++ b/Documentation/filesystems/btrfs.txt @@ -38,7 +38,7 @@ Mount Options ============= When mounting a btrfs filesystem, the following option are accepted. -Unless otherwise specified, all options default to off. +Options with (*) are default options and will not show in the mount options. alloc_start= Debugging option to force all block allocations above a certain @@ -138,12 +138,13 @@ Unless otherwise specified, all options default to off. Disable support for Posix Access Control Lists (ACLs). See the acl(5) manual page for more information about ACLs. + barrier(*) nobarrier - Disables the use of block layer write barriers. Write barriers ensure - that certain IOs make it through the device cache and are on persistent - storage. If used on a device with a volatile (non-battery-backed) - write-back cache, this option will lead to filesystem corruption on a - system crash or power loss. + Enable/disable the use of block layer write barriers. Write barriers + ensure that certain IOs make it through the device cache and are on + persistent storage. If disabled on a device with a volatile + (non-battery-backed) write-back cache, nobarrier option will lead to + filesystem corruption on a system crash or power loss. nodatacow Disable data copy-on-write for newly created files. Implies nodatasum, diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index e9c13fb..fe9d8a6 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -323,7 +323,7 @@ enum { Opt_no_space_cache, Opt_recovery, Opt_skip_balance, Opt_check_integrity, Opt_check_integrity_including_extent_data, Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree, - Opt_commit_interval, + Opt_commit_interval, Opt_barrier, Opt_err, }; @@ -335,6 +335,7 @@ static match_table_t tokens = { {Opt_nodatasum, "nodatasum"}, {Opt_nodatacow, "nodatacow"}, {Opt_nobarrier, "nobarrier"}, + {Opt_barrier, "barrier"}, {Opt_max_inline, "max_inline=%s"}, {Opt_alloc_start, "alloc_start=%s"}, {Opt_thread_pool, "thread_pool=%d"}, @@ -494,6 +495,11 @@ int btrfs_parse_options(struct btrfs_root *root, char *options) btrfs_clear_opt(info->mount_opt, SSD); btrfs_clear_opt(info->mount_opt, SSD_SPREAD); break; + case Opt_barrier: + if (btrfs_test_opt(root, NOBARRIER)) + btrfs_info(root->fs_info, "turning on barriers"); + btrfs_clear_opt(info->mount_opt, NOBARRIER); + break; case Opt_nobarrier: btrfs_info(root->fs_info, "turning off barriers"); btrfs_set_opt(info->mount_opt, NOBARRIER); -- 1.8.5.2