jbd2: fix sending of data flush on journal commit
In data=ordered mode, it's theoretically possible (however rare) that
an inode is filed to transaction's t_inode_list and a flusher thread
writes all the data and inode is reclaimed before the transaction
starts to commit. In such a case, we could erroneously omit sending a
flush to file system device when it is different from the journal
device (because data can still be in disk cache only).
Fix the problem by setting a flag in a transaction when some inode is added
to it and then send disk flush in the commit code when the flag is set.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 85a055e..20065c9 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2147,6 +2147,13 @@
jinode->i_next_transaction == transaction)
goto done;
+ /*
+ * We only ever set this variable to 1 so the test is safe. Since
+ * t_need_data_flush is likely to be set, we do the test to save some
+ * cacheline bouncing
+ */
+ if (!transaction->t_need_data_flush)
+ transaction->t_need_data_flush = 1;
/* On some different transaction's list - should be
* the committing one */
if (jinode->i_transaction) {