Merge tag 'mfd-for-linus-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo...

[~andy/linux] / fs / xfs / xfs_log.c

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 7f4f9370d0e7438df3820fab9b0026b37292623b..4dad756962d02e1b29c703b5b54ccee07d91fabf 100644 (file)
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2387,14 +2387,27 @@ xlog_state_do_callback(
 
 
                                /*
-                                * update the last_sync_lsn before we drop the
+                                * Completion of a iclog IO does not imply that
+                                * a transaction has completed, as transactions
+                                * can be large enough to span many iclogs. We
+                                * cannot change the tail of the log half way
+                                * through a transaction as this may be the only
+                                * transaction in the log and moving th etail to
+                                * point to the middle of it will prevent
+                                * recovery from finding the start of the
+                                * transaction. Hence we should only update the
+                                * last_sync_lsn if this iclog contains
+                                * transaction completion callbacks on it.
+                                *
+                                * We have to do this before we drop the
                                 * icloglock to ensure we are the only one that
                                 * can update it.
                                 */
                                ASSERT(XFS_LSN_CMP(atomic64_read(&log->l_last_sync_lsn),
                                        be64_to_cpu(iclog->ic_header.h_lsn)) <= 0);
-                               atomic64_set(&log->l_last_sync_lsn,
-                                       be64_to_cpu(iclog->ic_header.h_lsn));
+                               if (iclog->ic_callback)
+                                       atomic64_set(&log->l_last_sync_lsn,
+                                               be64_to_cpu(iclog->ic_header.h_lsn));
 
                        } else
                                ioerrors++;