On Thu, 2 Jan 2014 16:41:03 +0100, David Sterba wrote:
On Thu, Dec 26, 2013 at 02:45:10PM +0800, 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)
Ok for adding the mount option.
Reported-by: Daniel Blueman <dan...@quora.org>
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
Documentation/filesystems/btrfs.txt | 6 ++++++
fs/btrfs/super.c | 8 +++++++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/Documentation/filesystems/btrfs.txt
b/Documentation/filesystems/btrfs.txt
index 5dd282d..f6f71d6 100644
--- a/Documentation/filesystems/btrfs.txt
+++ b/Documentation/filesystems/btrfs.txt
@@ -51,6 +51,12 @@ Unless otherwise specified, all options default to off.
defrag process. Works best for small files; Not well suited for
large database workloads.
+ barrier
+ Enable the use of block layer write barriers. Write barriers ensure
+ that certain IOs make it through the device cache and are on persistent
+ storage.
+ Barriers are enabled by default.
There's the 'nobarrier' option already, I think it's better to keep the
pairing option documentation at one place and mark the default one with (*).
Related to that, there should imho be a pairing option for every mount
option where it makes sense, so all the combinations work through
remount.
The defaults do not need to be listed via btrfs_show_options, ie. keep
the output same as it is now.
david
Thanks for pointing out these problem.
This makes sense.Like space_cache and nospace_cache follows the way you
mentioned,
but most other options just followed the alphabet order, and a lot of
pairing is missing.
I'll try to add all the missingpairing and unify mount options in the
document.
Qu
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