ocfs2: Support nested transactions

OCFS2 can easily support nested transactions. We just have to
take care and not spoil statistics acquire semaphore unnecessarily.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 12b62a3..11a1178 100644 (file)
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -256,11 +256,9 @@ handle_t *ocfs2_start_trans(struct ocfs2_super *osb, int max_buffs)
        BUG_ON(osb->journal->j_state == OCFS2_JOURNAL_FREE);
        BUG_ON(max_buffs <= 0);
 
-       /* JBD might support this, but our journalling code doesn't yet. */
-       if (journal_current_handle()) {
-               mlog(ML_ERROR, "Recursive transaction attempted!\n");
-               BUG();
-       }
+       /* Nested transaction? Just return the handle... */
+       if (journal_current_handle())
+               return jbd2_journal_start(journal, max_buffs);
 
        down_read(&osb->journal->j_trans_barrier);
 
@@ -285,16 +283,18 @@ handle_t *ocfs2_start_trans(struct ocfs2_super *osb, int max_buffs)
 int ocfs2_commit_trans(struct ocfs2_super *osb,
                       handle_t *handle)
 {
-       int ret;
+       int ret, nested;
        struct ocfs2_journal *journal = osb->journal;
 
        BUG_ON(!handle);
 
+       nested = handle->h_ref > 1;
        ret = jbd2_journal_stop(handle);
        if (ret < 0)
                mlog_errno(ret);
 
-       up_read(&journal->j_trans_barrier);
+       if (!nested)
+               up_read(&journal->j_trans_barrier);
 
        return ret;
 }