From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([222.73.24.84]:60129 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750863AbaACJT0 (ORCPT ); Fri, 3 Jan 2014 04:19:26 -0500 Message-ID: <52C680CD.30604@cn.fujitsu.com> Date: Fri, 03 Jan 2014 17:20:13 +0800 From: Qu Wenruo MIME-Version: 1.0 To: Mike Fleetwood CC: linux-btrfs , David Sterba Subject: Re: [PATCH v2 01/11] btrfs: Add "barrier" option to support "-o remount,barrier" References: <1388729434-19799-1-git-send-email-quwenruo@cn.fujitsu.com> <1388729434-19799-2-git-send-email-quwenruo@cn.fujitsu.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On fri, 3 Jan 2014 08:44:30 +0000, Mike Fleetwood wrote: > On 3 January 2014 06:10, Qu Wenruo wrote: >> 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 >> Cc: David Sterba >> --- >> changelog: >> v1: Add barrier option >> v2: Change the document style to fit pairing options better >> --- >> 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..2d2e016 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. >> + Disable/enable the use of block layer write barriers. Write barriers > Please use > "Enable/Disable ..." > to match order on the options barrier(*) then nobarrier immediately above. > >> + ensure that certain IOs make it through the device cache and are on >> + persistent storage. If used on a device with a volatile > And: > "... If disabled on a device with a volatile" > to make more sense when both enable and disable options are listed. Thanks for pointing out the problem. I'll fix it soon. Qu >> + (non-battery-backed) write-back cache, this 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 >> > Thanks, > Mike > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >