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>

3 files changed, 17 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 */
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 9744ee920473..edfee24f3636 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -1131,6 +1131,8 @@ static int fill_super(struct super_block *sb, struct gfs2_args *args, int silent
         }
         if (sdp->sd_args.ar_posix_acl)
                 sb->s_flags |= MS_POSIXACL;
+        if (sdp->sd_args.ar_nobarrier)
+                set_bit(SDF_NOBARRIERS, &sdp->sd_flags);
 
         sb->s_magic = GFS2_MAGIC;
         sb->s_op = &gfs2_super_ops;
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index b1dcfab36465..5e4b31441a9e 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -73,6 +73,8 @@ enum {
         Opt_statfs_quantum,
         Opt_statfs_percent,
         Opt_quota_quantum,
+        Opt_barrier,
+        Opt_nobarrier,
         Opt_error,
 };
 
@@ -107,6 +109,8 @@ static const match_table_t tokens = {
         {Opt_statfs_quantum, "statfs_quantum=%d"},
         {Opt_statfs_percent, "statfs_percent=%d"},
         {Opt_quota_quantum, "quota_quantum=%d"},
+        {Opt_barrier, "barrier"},
+        {Opt_nobarrier, "nobarrier"},
         {Opt_error, NULL}
 };
 
@@ -253,6 +257,12 @@ int gfs2_mount_args(struct gfs2_args *args, char *options)
                         }
                         args->ar_errors = GFS2_ERRORS_PANIC;
                         break;
+                case Opt_barrier:
+                        args->ar_nobarrier = 0;
+                        break;
+                case Opt_nobarrier:
+                        args->ar_nobarrier = 1;
+                        break;
                 case Opt_error:
                 default:
                         printk(KERN_WARNING "GFS2: invalid mount option: %s\n", o);
@@ -1143,6 +1153,10 @@ static int gfs2_remount_fs(struct super_block *sb, int *flags, char *data)
                 sb->s_flags |= MS_POSIXACL;
         else
                 sb->s_flags &= ~MS_POSIXACL;
+        if (sdp->sd_args.ar_nobarrier)
+                set_bit(SDF_NOBARRIERS, &sdp->sd_flags);
+        else
+                clear_bit(SDF_NOBARRIERS, &sdp->sd_flags);
         spin_lock(&gt->gt_spin);
         gt->gt_log_flush_secs = args.ar_commit;
         gt->gt_quota_quantum = args.ar_quota_quantum;