GFS2: add barrier/nobarrier mount options

Currently gfs2 issues barrier unconditionally.  There are various reasons
to disable them, be that just for testing or for stupid devices flushing
large battert backed caches.  Add a nobarrier option that matches xfs and
btrfs for this.  Also add a symmetric barrier option to turn it back on
at remount time.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index c239b0f969c8..4792200978c8 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -429,6 +429,7 @@ struct gfs2_args {
         unsigned int ar_meta:1;                 /* mount metafs */
         unsigned int ar_discard:1;              /* discard requests */
         unsigned int ar_errors:2;               /* errors=withdraw | panic */
+        unsigned int ar_nobarrier:1;            /* do not send barriers */
         int ar_commit;                          /* Commit interval */
         int ar_statfs_quantum;                  /* The fast statfs interval */
         int ar_quota_quantum;                   /* The quota interval */