Btrfs has btrfs_end_transaction_throttle() which could try to commit
transaction when needed.
However under most cases btrfs_end_transaction_throttle() won't really
commit transaction, due to the hard timing requirement.
Now introduce a new error injection point, btrfs_need_trans_pressure(),
to allow btrfs_should_end_transaction() to return 1 and
btrfs_end_transaction_throttle() to fallback to
btrfs_commit_transaction().
With such more aggressive transaction commit, we can dig deeper into
cases like snapshot drop.
Now each reference drop of btrfs_drop_snapshot() will lead to a
transaction commit, allowing dm-logwrites to catch more details, other
than one big transaction dropping everything.
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
fs/btrfs/transaction.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 248d535bb14d..2e758957126e 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -10,6 +10,7 @@
#include <linux/pagemap.h>
#include <linux/blkdev.h>
#include <linux/uuid.h>
+#include <linux/error-injection.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
@@ -781,10 +782,18 @@ void btrfs_throttle(struct btrfs_fs_info *fs_info)
wait_current_trans(fs_info);
}
+static noinline bool btrfs_need_trans_pressure(struct btrfs_trans_handle *trans)
+{
+ return false;
+}
+ALLOW_ERROR_INJECTION(btrfs_need_trans_pressure, TRUE);
+
static int should_end_transaction(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
+ if (btrfs_need_trans_pressure(trans))
+ return 1;
if (btrfs_check_space_for_delayed_refs(fs_info))
return 1;
@@ -845,6 +854,8 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
btrfs_trans_release_chunk_metadata(trans);
+ if (throttle && btrfs_need_trans_pressure(trans))
+ return btrfs_commit_transaction(trans);
if (lock && READ_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
if (throttle)
return btrfs_commit_transaction(trans);
--
2.22.0
