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Commit 20b297d6 authored by Jan Schmidt's avatar Jan Schmidt
Browse files

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: default avatarJan Schmidt <list.btrfs@jan-o-sch.net>
parent 19ae4e81

fs/btrfs/transaction.c

+18 −0
Original line number Diff line number Diff line
@@ -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);