From: Qu Wenruo <wqu@suse.com>
To: linux-btrfs@vger.kernel.org
Subject: [PATCH v2] btrfs: transaction: Commit transaction more frequently for BPF
Date: Thu, 15 Aug 2019 16:04:04 +0800 [thread overview]
Message-ID: <20190815080404.20600-1-wqu@suse.com> (raw)
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@suse.com>
---
Changelog:
v2:
- Add comment to explain why this function is needed
---
fs/btrfs/transaction.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 3f6811cdf803..8c5471b01d03 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"
@@ -749,10 +750,25 @@ void btrfs_throttle(struct btrfs_fs_info *fs_info)
wait_current_trans(fs_info);
}
+/*
+ * This function is to allow BPF to override the return value so that we can
+ * make btrfs to commit transaction more aggressively.
+ *
+ * It's a debug only feature, mainly used with dm-log-writes to catch more details
+ * of transient operations like balance and subvolume drop.
+ */
+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;
@@ -813,6 +829,8 @@ 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
next reply other threads:[~2019-08-15 8:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-15 8:04 Qu Wenruo [this message]
2019-08-16 9:33 ` [PATCH v2] btrfs: transaction: Commit transaction more frequently for BPF Filipe Manana
2019-08-16 9:53 ` Qu Wenruo
2019-08-16 10:03 ` Filipe Manana
2019-08-16 10:06 ` Qu Wenruo
2019-08-19 16:57 ` David Sterba
2019-08-20 0:34 ` Qu Wenruo
2019-08-19 5:14 ` Qu Wenruo
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