[PATCH] jbd2: Skip commit of a transaction without any buffers

[Jan Kara]

Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 fs/jbd2/commit.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index ebc667b..798e021 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -401,6 +401,21 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	J_ASSERT (commit_transaction->t_outstanding_credits <=
 			journal->j_max_transaction_buffers);
 
+	/* Skip commit of a transaction without any buffers */
+	spin_lock(&journal->j_list_lock);
+	if (commit_transaction->t_reserved_list == NULL &&
+	    commit_transaction->t_buffers == NULL &&
+	    commit_transaction->t_forget == NULL &&
+	    list_empty(commit_transaction->t_inode_list)) {
+		BUG_ON(commit_transaction->t_checkpoint_list);
+		BUG_ON(commit_transaction->t_checkpoint_io_list);
+		BUG_ON(commit_transaction->t_iobuf_list);
+		BUG_ON(commit_transaction->t_shadow_list);
+		BUG_ON(commit_transaction->t_log_list);
+		goto out_committed;
+	}
+	spin_unlock(&journal->j_list_lock);
+
 	/*
 	 * First thing we are allowed to do is to discard any remaining
 	 * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
@@ -934,6 +949,7 @@ restart_loop:
 
 	/* Done with this transaction! */
 
+out_committed:
 	jbd_debug(3, "JBD: commit phase 7\n");
 
 	J_ASSERT(commit_transaction->t_state == T_COMMIT);
-- 
1.6.0.2

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