jbd: don't wait (forever) for stale tid caused by wraparound (e678a4f0) · Commits · 戴 / test

In the case where an inode has a very stale transaction id (tid) in i_datasync_tid or i_sync_tid, it's possible that after a very large (2**31) number of transactions, that the tid number space might wrap, causing tid_geq()'s calculations to fail. Commit "jbd: fix fsync() tid wraparound bug" attempted to fix this problem, but it only avoided kjournald spinning forever by fixing the logic in jbd_log_start_commit(). Signed-off-by:

Jan Kara <jack@suse.cz>

fs/jbd/journal.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -564,6 +564,16 @@ int log_wait_commit(journal_t *journal, tid_t tid)
		spin_unlock(&journal->j_state_lock);
		#endif
		spin_lock(&journal->j_state_lock);
		/*
		* Not running or committing trans? Must be already committed. This
		* saves us from waiting for a long time when tid overflows.
		*/
		if (!((journal->j_running_transaction &&
		journal->j_running_transaction->t_tid == tid) \|\|
		(journal->j_committing_transaction &&
		journal->j_committing_transaction->t_tid == tid)))
		goto out_unlock;

		if (!tid_geq(journal->j_commit_waited, tid))
		journal->j_commit_waited = tid;
		while (tid_gt(tid, journal->j_commit_sequence)) {
		@@ -575,6 +585,7 @@ int log_wait_commit(journal_t *journal, tid_t tid)
		!tid_gt(tid, journal->j_commit_sequence));
		spin_lock(&journal->j_state_lock);
		}
		out_unlock:
		spin_unlock(&journal->j_state_lock);

		if (unlikely(is_journal_aborted(journal))) {

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