[PATCH] reiserfs: handle trans_id overflow

Reiserfs does not handle transaction ID overflow correctly.  Transaction ID
== 0 causes reiserfs to crash.  The patch fixes all places where the
transaction ID is incremented.

Signed-off-by: Alexander Zarochentsev <zam@namesys.com>
Signed-off-by: Hans Reiser <reiser@namesys.com>
Cc: Chris Mason <mason@suse.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/reiserfs/journal.c

@@ -2227,6 +2227,9 @@ static int journal_read_transaction(struct super_block *p_s_sb,
 	journal->j_start = cur_dblock - SB_ONDISK_JOURNAL_1st_BLOCK(p_s_sb);
 	journal->j_last_flush_trans_id = trans_id;
 	journal->j_trans_id = trans_id + 1;
+	/* check for trans_id overflow */
+	if (journal->j_trans_id == 0)
+		journal->j_trans_id = 10;
 	brelse(c_bh);
 	brelse(d_bh);
 	kfree(log_blocks);
@@ -2450,6 +2453,9 @@ static int journal_read(struct super_block *p_s_sb)
 		journal->j_start = le32_to_cpu(jh->j_first_unflushed_offset);
 		journal->j_trans_id =
 		    le32_to_cpu(jh->j_last_flush_trans_id) + 1;
+		/* check for trans_id overflow */
+		if (journal->j_trans_id == 0)
+			journal->j_trans_id = 10;
 		journal->j_last_flush_trans_id =
 		    le32_to_cpu(jh->j_last_flush_trans_id);
 		journal->j_mount_id = le32_to_cpu(jh->j_mount_id) + 1;
@@ -3873,8 +3879,8 @@ static int do_journal_end(struct reiserfs_transaction_handle *th,
 	int cur_write_start = 0;	/* start index of current log write */
 	int old_start;
 	int i;
-	int flush = flags & FLUSH_ALL;
-	int wait_on_commit = flags & WAIT;
+	int flush;
+	int wait_on_commit;
 	struct reiserfs_journal_list *jl, *temp_jl;
 	struct list_head *entry, *safe;
 	unsigned long jindex;
@@ -3884,6 +3890,13 @@ static int do_journal_end(struct reiserfs_transaction_handle *th,
 	BUG_ON(th->t_refcount > 1);
 	BUG_ON(!th->t_trans_id);
 
+	/* protect flush_older_commits from doing mistakes if the
+           transaction ID counter gets overflowed.  */
+	if (th->t_trans_id == ~0UL)
+		flags |= FLUSH_ALL | COMMIT_NOW | WAIT;
+	flush = flags & FLUSH_ALL;
+	wait_on_commit = flags & WAIT;
+
 	put_fs_excl();
 	current->journal_info = th->t_handle_save;
 	reiserfs_check_lock_depth(p_s_sb, "journal end");
@@ -4105,7 +4118,9 @@ static int do_journal_end(struct reiserfs_transaction_handle *th,
 	journal->j_first = NULL;
 	journal->j_len = 0;
 	journal->j_trans_start_time = 0;
-	journal->j_trans_id++;
+	/* check for trans_id overflow */
+	if (++journal->j_trans_id == 0)
+		journal->j_trans_id = 10;
 	journal->j_current_jl->j_trans_id = journal->j_trans_id;
 	journal->j_must_wait = 0;
 	journal->j_len_alloc = 0;