ext4, jbd2: Add barriers for file systems with exernal journals

[net-next-2.6.git] / fs / jbd2 / checkpoint.c

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index ca0f5eb62b20e450b38ef84b52c64bc2a214bc17..886849370950f462627f0a9d2df692ec4d117d97 100644 (file)
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -22,6 +22,7 @@
 #include <linux/jbd2.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
+#include <linux/blkdev.h>
 #include <trace/events/jbd2.h>
 
 /*
@@ -515,6 +516,20 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
        journal->j_tail_sequence = first_tid;
        journal->j_tail = blocknr;
        spin_unlock(&journal->j_state_lock);
+
+       /*
+        * If there is an external journal, we need to make sure that
+        * any data blocks that were recently written out --- perhaps
+        * by jbd2_log_do_checkpoint() --- are flushed out before we
+        * drop the transactions from the external journal.  It's
+        * unlikely this will be necessary, especially with a
+        * appropriately sized journal, but we need this to guarantee
+        * correctness.  Fortunately jbd2_cleanup_journal_tail()
+        * doesn't get called all that often.
+        */
+       if ((journal->j_fs_dev != journal->j_dev) &&
+           (journal->j_flags & JBD2_BARRIER))
+               blkdev_issue_flush(journal->j_fs_dev, NULL);
        if (!(journal->j_flags & JBD2_ABORT))
                jbd2_journal_update_superblock(journal, 1);
        return 0;