From 20b297d620cd1bb94127942bbb3702fb7b1030b2 Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Sun, 20 May 2012 15:43:53 +0200 Subject: [PATCH] Btrfs: tree mod log sanity checks in join_transaction When a fresh transaction begins, the tree mod log must be clean. Users of the tree modification log must ensure they never span across transaction boundaries. We reset the sequence to 0 in this safe situation to make absolutely sure overflow can't happen. Signed-off-by: Jan Schmidt --- fs/btrfs/transaction.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index eb2bd826bb04..667735fb45e6 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -122,6 +122,24 @@ loop: cur_trans->delayed_refs.flushing = 0; cur_trans->delayed_refs.run_delayed_start = 0; cur_trans->delayed_refs.seq = 1; + + /* + * although the tree mod log is per file system and not per transaction, + * the log must never go across transaction boundaries. + */ + smp_mb(); + if (!list_empty(&fs_info->tree_mod_seq_list)) { + printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when " + "creating a fresh transaction\n"); + WARN_ON(1); + } + if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) { + printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when " + "creating a fresh transaction\n"); + WARN_ON(1); + } + atomic_set(&fs_info->tree_mod_seq, 0); + init_waitqueue_head(&cur_trans->delayed_refs.seq_wait); spin_lock_init(&cur_trans->commit_lock); spin_lock_init(&cur_trans->delayed_refs.lock); -- 2.20.1