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)
Reported-by: Daniel Blueman <dan...@quora.org>
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
Documentation/filesystems/btrfs.txt | 6 ++++++
fs/btrfs/super.c | 8 +++++++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/Documentation/filesystems/btrfs.txt
b/Documentation/filesystems/btrfs.txt
index 5dd282d..f6f71d6 100644
--- a/Documentation/filesystems/btrfs.txt
+++ b/Documentation/filesystems/btrfs.txt
@@ -51,6 +51,12 @@ Unless otherwise specified, all options default to off.
defrag process. Works best for small files; Not well suited for
large database workloads.
+ barrier
+ Enable the use of block layer write barriers. Write barriers ensure
+ that certain IOs make it through the device cache and are on persistent
+ storage.
+ Barriers are enabled by default.
+
check_int
check_int_data
check_int_print_mask=<value>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index e9c13fb..c8f4aca 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -323,7 +323,7 @@ enum {
Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
Opt_check_integrity, Opt_check_integrity_including_extent_data,
Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
- Opt_commit_interval,
+ Opt_commit_interval, Opt_barrier,
Opt_err,
};
@@ -335,6 +335,7 @@ static match_table_t tokens = {
{Opt_nodatasum, "nodatasum"},
{Opt_nodatacow, "nodatacow"},
{Opt_nobarrier, "nobarrier"},
+ {Opt_barrier, "barrier"},
{Opt_max_inline, "max_inline=%s"},
{Opt_alloc_start, "alloc_start=%s"},
{Opt_thread_pool, "thread_pool=%d"},
@@ -498,6 +499,11 @@ int btrfs_parse_options(struct btrfs_root *root, char
*options)
btrfs_info(root->fs_info, "turning off barriers");
btrfs_set_opt(info->mount_opt, NOBARRIER);
break;
+ case Opt_barrier:
+ if (btrfs_test_opt(root, NOBARRIER))
+ btrfs_info(root->fs_info, "turning on
barriers");
+ btrfs_clear_opt(info->mount_opt, NOBARRIER);
+ break;
case Opt_thread_pool:
ret = match_int(&args[0], &intarg);
if (ret) {
--
1.8.5.2
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