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authorQu Wenruo <quwenruo@cn.fujitsu.com>2014-01-06 09:58:25 +0800
committerChris Mason <clm@fb.com>2014-01-28 13:20:16 -0800
commit842bef5891aaf13e2dede01d86397d810fde2dd8 (patch)
tree33b072d33c9c2479cf78e0fdc31bb8be03985349 /Documentation
parente8117c26b24098496b6011aabe84e43e0189a506 (diff)
btrfs: Add "barrier" option to support "-o remount,barrier"
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 <daniel@quora.org> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: Mike Fleetwood <mike.fleetwood@googlemail.com> Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/btrfs.txt13
1 files changed, 7 insertions, 6 deletions
diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt
index 5dd282dda55c..ce487a2a88f8 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=<bytes>
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,