jbd: fix possible journal overflow issues

[firefly-linux-kernel-4.4.55.git] / fs / jbd / transaction.c

diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c
index 2e9670e2237e96650ba3d41f0e817b870e5bbb80..d8dd3d915fd9311d57288f3b6b54bae93d385108 100644 (file)
--- a/fs/jbd/transaction.c
+++ b/fs/jbd/transaction.c
@@ -1235,6 +1235,7 @@ int journal_forget (handle_t *handle, struct buffer_head *bh)
        struct journal_head *jh;
        int drop_reserve = 0;
        int err = 0;
+       int was_modified = 0;
 
        BUFFER_TRACE(bh, "entry");
 
@@ -1253,6 +1254,9 @@ int journal_forget (handle_t *handle, struct buffer_head *bh)
                goto not_jbd;
        }
 
+       /* keep track of wether or not this transaction modified us */
+       was_modified = jh->b_modified;
+
        /*
         * The buffer's going from the transaction, we must drop
         * all references -bzzz
@@ -1270,7 +1274,12 @@ int journal_forget (handle_t *handle, struct buffer_head *bh)
 
                JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
 
-               drop_reserve = 1;
+               /*
+                * we only want to drop a reference if this transaction
+                * modified the buffer
+                */
+               if (was_modified)
+                       drop_reserve = 1;
 
                /*
                 * We are no longer going to journal this buffer.
@@ -1310,7 +1319,13 @@ int journal_forget (handle_t *handle, struct buffer_head *bh)
                if (jh->b_next_transaction) {
                        J_ASSERT(jh->b_next_transaction == transaction);
                        jh->b_next_transaction = NULL;
-                       drop_reserve = 1;
+
+                       /*
+                        * only drop a reference if this transaction modified
+                        * the buffer
+                        */
+                       if (was_modified)
+                               drop_reserve = 1;
                }
        }
 
@@ -2082,7 +2097,7 @@ void __journal_refile_buffer(struct journal_head *jh)
        jh->b_transaction = jh->b_next_transaction;
        jh->b_next_transaction = NULL;
        __journal_file_buffer(jh, jh->b_transaction,
-                               was_dirty ? BJ_Metadata : BJ_Reserved);
+                               jh->b_modified ? BJ_Metadata : BJ_Reserved);
        J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
 
        if (was_dirty)