From fdfbf020664b92336ac4f554ffec2d2f890960b9 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 5 Nov 2021 16:45:28 -0400 Subject: [PATCH] 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 [ add note ] Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/ctree.h | 3 ++ fs/btrfs/disk-io.c | 3 +- fs/btrfs/ioctl.c | 7 +---- fs/btrfs/transaction.c | 64 ++++++++---------------------------------- fs/btrfs/transaction.h | 2 +- 5 files changed, 18 insertions(+), 61 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index f9e9f08175be..6474e3094dae 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -595,6 +595,9 @@ enum { /* Indicate whether there are any tree modification log users */ BTRFS_FS_TREE_MOD_LOG_USERS, + /* Indicate that we want the transaction kthread to commit right now. */ + BTRFS_FS_COMMIT_TRANS, + #if BITS_PER_LONG == 32 /* Indicate if we have error/warn message printed on 32bit systems */ BTRFS_FS_32BIT_ERROR, diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index de323878e85c..9683b507be50 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1934,7 +1934,8 @@ static int transaction_kthread(void *arg) } delta = ktime_get_seconds() - cur->start_time; - if (cur->state < TRANS_STATE_COMMIT_START && + if (!test_and_clear_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags) && + cur->state < TRANS_STATE_COMMIT_START && delta < fs_info->commit_interval) { spin_unlock(&fs_info->trans_lock); delay -= msecs_to_jiffies((delta - 1) * 1000); diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 441d5130a4ec..af77098fdf35 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -3622,7 +3622,6 @@ static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root, { struct btrfs_trans_handle *trans; u64 transid; - int ret; trans = btrfs_attach_transaction_barrier(root); if (IS_ERR(trans)) { @@ -3634,11 +3633,7 @@ static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root, goto out; } transid = trans->transid; - ret = btrfs_commit_transaction_async(trans); - if (ret) { - btrfs_end_transaction(trans); - return ret; - } + btrfs_commit_transaction_async(trans); out: if (argp) if (copy_to_user(argp, &transid, sizeof(transid))) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 8b6a90fafcd4..3538980a5dda 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; @@ -1931,14 +1895,6 @@ 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 @@ -1946,14 +1902,9 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans) 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; diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index ba45065f9451..e4b9b251a29e 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -217,7 +217,7 @@ void btrfs_add_dead_root(struct btrfs_root *root); int btrfs_defrag_root(struct btrfs_root *root); int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root); int btrfs_commit_transaction(struct btrfs_trans_handle *trans); -int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans); +void btrfs_commit_transaction_async(struct btrfs_trans_handle *trans); int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans); bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans); void btrfs_throttle(struct btrfs_fs_info *fs_info);