ext4: Support for synchronous DAX faults
We return IOMAP_F_DIRTY flag from ext4_iomap_begin() when asked to
prepare blocks for writing and the inode has some uncommitted metadata
changes. In the fault handler ext4_dax_fault() we then detect this case
(through VM_FAULT_NEEDDSYNC return value) and call helper
dax_finish_sync_fault() to flush metadata changes and insert page table
entry. Note that this will also dirty corresponding radix tree entry
which is what we want - fsync(2) will still provide data integrity
guarantees for applications not using userspace flushing. And
applications using userspace flushing can avoid calling fsync(2) and
thus avoid the performance overhead.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 7d5ef3b..fa8cde4 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -738,6 +738,23 @@
return err;
}
+/* Return 1 when transaction with given tid has already committed. */
+int jbd2_transaction_committed(journal_t *journal, tid_t tid)
+{
+ int ret = 1;
+
+ read_lock(&journal->j_state_lock);
+ if (journal->j_running_transaction &&
+ journal->j_running_transaction->t_tid == tid)
+ ret = 0;
+ if (journal->j_committing_transaction &&
+ journal->j_committing_transaction->t_tid == tid)
+ ret = 0;
+ read_unlock(&journal->j_state_lock);
+ return ret;
+}
+EXPORT_SYMBOL(jbd2_transaction_committed);
+
/*
* When this function returns the transaction corresponding to tid
* will be completed. If the transaction has currently running, start