btrfs: rework async transaction committing
Currently we do this awful thing where we get another ref on a trans
handle, async off that handle and commit the transaction from that work.
Because we do this we have to mess with current->journal_info and the
freeze counting stuff.
We already have an async thing to kick for the transaction commit, the
transaction kthread. Replace this work struct with a flag on the
fs_info to tell the kthread to go ahead and commit even if it's before
our timeout. Then we can drastically simplify the async transaction
commit path.
Note: this can be simplified and functionality based on the pending
operation COMMIT.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add note ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 8b6a90f..3538980 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1880,50 +1880,14 @@ int btrfs_transaction_blocked(struct btrfs_fs_info *info)
return ret;
}
-/*
- * commit transactions asynchronously. once btrfs_commit_transaction_async
- * returns, any subsequent transaction will not be allowed to join.
- */
-struct btrfs_async_commit {
- struct btrfs_trans_handle *newtrans;
- struct work_struct work;
-};
-
-static void do_async_commit(struct work_struct *work)
-{
- struct btrfs_async_commit *ac =
- container_of(work, struct btrfs_async_commit, work);
-
- /*
- * We've got freeze protection passed with the transaction.
- * Tell lockdep about it.
- */
- if (ac->newtrans->type & __TRANS_FREEZABLE)
- __sb_writers_acquired(ac->newtrans->fs_info->sb, SB_FREEZE_FS);
-
- current->journal_info = ac->newtrans;
-
- btrfs_commit_transaction(ac->newtrans);
- kfree(ac);
-}
-
-int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)
+void btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
- struct btrfs_async_commit *ac;
struct btrfs_transaction *cur_trans;
- ac = kmalloc(sizeof(*ac), GFP_NOFS);
- if (!ac)
- return -ENOMEM;
-
- INIT_WORK(&ac->work, do_async_commit);
- ac->newtrans = btrfs_join_transaction(trans->root);
- if (IS_ERR(ac->newtrans)) {
- int err = PTR_ERR(ac->newtrans);
- kfree(ac);
- return err;
- }
+ /* Kick the transaction kthread. */
+ set_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);
+ wake_up_process(fs_info->transaction_kthread);
/* take transaction reference */
cur_trans = trans->transaction;
@@ -1932,28 +1896,15 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)
btrfs_end_transaction(trans);
/*
- * Tell lockdep we've released the freeze rwsem, since the
- * async commit thread will be the one to unlock it.
- */
- if (ac->newtrans->type & __TRANS_FREEZABLE)
- __sb_writers_release(fs_info->sb, SB_FREEZE_FS);
-
- schedule_work(&ac->work);
- /*
* Wait for the current transaction commit to start and block
* subsequent transaction joins
*/
wait_event(fs_info->transaction_blocked_wait,
cur_trans->state >= TRANS_STATE_COMMIT_START ||
TRANS_ABORTED(cur_trans));
- if (current->journal_info == trans)
- current->journal_info = NULL;
-
btrfs_put_transaction(cur_trans);
- return 0;
}
-
static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
@@ -2219,6 +2170,13 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
wait_event(cur_trans->writer_wait,
atomic_read(&cur_trans->num_writers) == 1);
+ /*
+ * We've started the commit, clear the flag in case we were triggered to
+ * do an async commit but somebody else started before the transaction
+ * kthread could do the work.
+ */
+ clear_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);
+
if (TRANS_ABORTED(cur_trans)) {
ret = cur_trans->aborted;
goto scrub_continue;