From 50d9aa99bd35c77200e0e3dd7a72274f8304701f Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 21 Nov 2014 14:52:38 -0500 Subject: Btrfs: make sure logged extents complete in the current transaction V3 Liu Bo pointed out that my previous fix would lose the generation update in the scenario I described. It is actually much worse than that, we could lose the entire extent if we lose power right after the transaction commits. Consider the following write extent 0-4k log extent in log tree commit transaction < power fail happens here ordered extent completes We would lose the 0-4k extent because it hasn't updated the actual fs tree, and the transaction commit will reset the log so it isn't replayed. If we lose power before the transaction commit we are save, otherwise we are not. Fix this by keeping track of all extents we logged in this transaction. Then when we go to commit the transaction make sure we wait for all of those ordered extents to complete before proceeding. This will make sure that if we lose power after the transaction commit we still have our data. This also fixes the problem of the improperly updated extent generation. Thanks, cc: stable@vger.kernel.org Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/transaction.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'fs/btrfs/transaction.c') diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 16c704b..295a135 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -247,6 +247,7 @@ loop: INIT_LIST_HEAD(&cur_trans->pending_snapshots); INIT_LIST_HEAD(&cur_trans->pending_chunks); INIT_LIST_HEAD(&cur_trans->switch_commits); + INIT_LIST_HEAD(&cur_trans->pending_ordered); list_add_tail(&cur_trans->list, &fs_info->trans_list); extent_io_tree_init(&cur_trans->dirty_pages, fs_info->btree_inode->i_mapping); @@ -515,6 +516,7 @@ again: h->sync = false; INIT_LIST_HEAD(&h->qgroup_ref_list); INIT_LIST_HEAD(&h->new_bgs); + INIT_LIST_HEAD(&h->ordered); smp_mb(); if (cur_trans->state >= TRANS_STATE_BLOCKED && @@ -746,6 +748,12 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, if (!list_empty(&trans->new_bgs)) btrfs_create_pending_block_groups(trans, root); + if (!list_empty(&trans->ordered)) { + spin_lock(&info->trans_lock); + list_splice(&trans->ordered, &cur_trans->pending_ordered); + spin_unlock(&info->trans_lock); + } + trans->delayed_ref_updates = 0; if (!trans->sync) { must_run_delayed_refs = @@ -1715,6 +1723,28 @@ static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info) btrfs_wait_ordered_roots(fs_info, -1); } +static inline void +btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans, + struct btrfs_fs_info *fs_info) +{ + struct btrfs_ordered_extent *ordered; + + spin_lock(&fs_info->trans_lock); + while (!list_empty(&cur_trans->pending_ordered)) { + ordered = list_first_entry(&cur_trans->pending_ordered, + struct btrfs_ordered_extent, + trans_list); + list_del_init(&ordered->trans_list); + spin_unlock(&fs_info->trans_lock); + + wait_event(ordered->wait, test_bit(BTRFS_ORDERED_COMPLETE, + &ordered->flags)); + btrfs_put_ordered_extent(ordered); + spin_lock(&fs_info->trans_lock); + } + spin_unlock(&fs_info->trans_lock); +} + int btrfs_commit_transaction(struct btrfs_trans_handle *trans, struct btrfs_root *root) { @@ -1765,6 +1795,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, } spin_lock(&root->fs_info->trans_lock); + list_splice(&trans->ordered, &cur_trans->pending_ordered); if (cur_trans->state >= TRANS_STATE_COMMIT_START) { spin_unlock(&root->fs_info->trans_lock); atomic_inc(&cur_trans->use_count); @@ -1817,6 +1848,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, btrfs_wait_delalloc_flush(root->fs_info); + btrfs_wait_pending_ordered(cur_trans, root->fs_info); + btrfs_scrub_pause(root); /* * Ok now we need to make sure to block out any other joins while we -- cgit v1.1