[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>

1 files changed, 18 insertions, 3 deletions

diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 5a9d2722fa0a..1b73529b8099 100644
--- a/fs/reiserfs/journal.c
+++ b/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;