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authorJan Schmidt <list.btrfs@jan-o-sch.net>2012-05-20 15:43:53 +0200
committerJan Schmidt <list.btrfs@jan-o-sch.net>2012-05-30 15:17:36 +0200
commit20b297d620cd1bb94127942bbb3702fb7b1030b2 (patch)
tree45e1d42c376b168ae55460e2d481f915d6cc8b78 /fs/btrfs/transaction.c
parent19ae4e8133f370d820c4cdd61a4b703235664a5f (diff)
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 <list.btrfs@jan-o-sch.net>
Diffstat (limited to 'fs/btrfs/transaction.c')
-rw-r--r--fs/btrfs/transaction.c18
1 files changed, 18 insertions, 0 deletions
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);