Btrfs: add flushoncommit mount option
The 'flushoncommit' mount option forces any data dirtied by a write in a
prior transaction to commit as part of the current commit. This makes
the committed state a fully consistent view of the file system from the
application's perspective (i.e., it includes all completed file system
operations). This was previously the behavior only when a snapshot is
created.
This is used by Ceph to ensure that completed writes make it to the
platter along with the metadata operations they are bound to (by
BTRFS_IOC_TRANS_{START,END}).
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 3baa2c1..9744af9 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -68,7 +68,7 @@
Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
Opt_ssd, Opt_thread_pool, Opt_noacl, Opt_compress, Opt_notreelog,
- Opt_err,
+ Opt_flushoncommit, Opt_err,
};
static match_table_t tokens = {
@@ -86,6 +86,7 @@
{Opt_ssd, "ssd"},
{Opt_noacl, "noacl"},
{Opt_notreelog, "notreelog"},
+ {Opt_flushoncommit, "flushoncommit"},
{Opt_err, NULL},
};
@@ -229,6 +230,10 @@
printk(KERN_INFO "btrfs: disabling tree log\n");
btrfs_set_opt(info->mount_opt, NOTREELOG);
break;
+ case Opt_flushoncommit:
+ printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
+ btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
+ break;
default:
break;
}
@@ -370,9 +375,8 @@
int btrfs_sync_fs(struct super_block *sb, int wait)
{
struct btrfs_trans_handle *trans;
- struct btrfs_root *root;
+ struct btrfs_root *root = btrfs_sb(sb);
int ret;
- root = btrfs_sb(sb);
if (sb->s_flags & MS_RDONLY)
return 0;
@@ -419,7 +423,9 @@
if (btrfs_test_opt(root, SSD))
seq_puts(seq, ",ssd");
if (btrfs_test_opt(root, NOTREELOG))
- seq_puts(seq, ",notreelog");
+ seq_puts(seq, ",no-treelog");
+ if (btrfs_test_opt(root, FLUSHONCOMMIT))
+ seq_puts(seq, ",flush-on-commit");
if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
seq_puts(seq, ",noacl");
return 0;