- * All metadata updates are logged, which means that we just have
- * to flush the log up to the latest LSN that touched the inode.
+ * All metadata updates are logged, which means that we just have to
+ * flush the log up to the latest LSN that touched the inode. If we have
+ * concurrent fsync/fdatasync() calls, we need them to all block on the
+ * log force before we clear the ili_fsync_fields field. This ensures
+ * that we don't get a racing sync operation that does not wait for the
+ * metadata to hit the journal before returning. If we race with
+ * clearing the ili_fsync_fields, then all that will happen is the log
+ * force will do nothing as the lsn will already be on disk. We can't
+ * race with setting ili_fsync_fields because that is done under
+ * XFS_ILOCK_EXCL, and that can't happen because we hold the lock shared
+ * until after the ili_fsync_fields is cleared.