Btrfs: Add flush barriers on commit

Signed-off-by: Chris Mason <chris.mason@oracle.com>

3 files changed, 16 insertions, 3 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7eda51542d17..0c0edacbc14c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -440,8 +440,9 @@ struct btrfs_root {
  */
 #define BTRFS_STRING_ITEM_KEY   253
 
-#define BTRFS_MOUNT_NODATASUM           0x1
-#define BTRFS_MOUNT_NODATACOW           0x2
+#define BTRFS_MOUNT_NODATASUM           (1 << 0)
+#define BTRFS_MOUNT_NODATACOW           (1 << 1)
+#define BTRFS_MOUNT_NOBARRIER           (1 << 2)
 
 #define btrfs_clear_opt(o, opt)         ((o) &= ~BTRFS_MOUNT_##opt)
 #define btrfs_set_opt(o, opt)           ((o) |= BTRFS_MOUNT_##opt)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e0940a39ff07..a481b970608c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -762,10 +762,15 @@ int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
         int ret;
         struct extent_buffer *super = root->fs_info->sb_buffer;
         struct inode *btree_inode = root->fs_info->btree_inode;
+        struct super_block *sb = root->fs_info->sb;
 
+        if (!btrfs_test_opt(root, NOBARRIER))
+                blkdev_issue_flush(sb->s_bdev, NULL);
         set_extent_buffer_dirty(&BTRFS_I(btree_inode)->extent_tree, super);
         ret = sync_page_range_nolock(btree_inode, btree_inode->i_mapping,
                                      super->start, super->len);
+        if (!btrfs_test_opt(root, NOBARRIER))
+                blkdev_issue_flush(sb->s_bdev, NULL);
         return ret;
 }
 
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f1b56eb77b1d..9ab4086d463c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -64,13 +64,14 @@ static void btrfs_put_super (struct super_block * sb)
 
 enum {
         Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent,
-        Opt_alloc_start, Opt_err,
+        Opt_alloc_start, Opt_nobarrier, Opt_err,
 };
 
 static match_table_t tokens = {
         {Opt_subvol, "subvol=%s"},
         {Opt_nodatasum, "nodatasum"},
         {Opt_nodatacow, "nodatacow"},
+        {Opt_nobarrier, "nobarrier"},
         {Opt_max_extent, "max_extent=%s"},
         {Opt_alloc_start, "alloc_start=%s"},
         {Opt_err, NULL}
@@ -148,6 +149,12 @@ static int parse_options (char * options,
                                 btrfs_set_opt(info->mount_opt, NODATASUM);
                         }
                         break;
+                case Opt_nobarrier:
+                        if (info) {
+                                printk("btrfs: turning off barriers\n");
+                                btrfs_set_opt(info->mount_opt, NOBARRIER);
+                        }
+                        break;
                 case Opt_max_extent:
                         if (info) {
                                 char *num = match_strdup(&args[0]);