1 files changed, 35 insertions, 6 deletions

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index b9b0b6f899b9..d6e006e67804 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -618,6 +618,12 @@ repeat:
                 goto done;
 
         /*
+         * this is the first time this transaction is touching this buffer,
+         * reset the modified flag
+         */
+       jh->b_modified = 0;
+
+        /*
          * If there is already a copy-out version of this buffer, then we don't
          * need to make another one
          */
@@ -690,7 +696,7 @@ repeat:
                                 if (!frozen_buffer) {
                                         printk(KERN_EMERG
                                                "%s: OOM for frozen_buffer\n",
-                                               __FUNCTION__);
+                                               __func__);
                                         JBUFFER_TRACE(jh, "oom!");
                                         error = -ENOMEM;
                                         jbd_lock_bh_state(bh);
@@ -829,9 +835,16 @@ int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
 
         if (jh->b_transaction == NULL) {
                 jh->b_transaction = transaction;
+
+                /* first access by this transaction */
+                jh->b_modified = 0;
+
                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
         } else if (jh->b_transaction == journal->j_committing_transaction) {
+                /* first access by this transaction */
+                jh->b_modified = 0;
+
                 JBUFFER_TRACE(jh, "set next transaction");
                 jh->b_next_transaction = transaction;
         }
@@ -901,7 +914,7 @@ repeat:
                 committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
                 if (!committed_data) {
                         printk(KERN_EMERG "%s: No memory for committed data\n",
-                                __FUNCTION__);
+                                __func__);
                         err = -ENOMEM;
                         goto out;
                 }
@@ -1230,6 +1243,7 @@ int jbd2_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");
 
@@ -1248,6 +1262,9 @@ int jbd2_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
@@ -1265,7 +1282,12 @@ int jbd2_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.
@@ -1305,7 +1327,13 @@ int jbd2_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;
                 }
         }
 
@@ -1434,7 +1462,8 @@ int jbd2_journal_stop(handle_t *handle)
         return err;
 }
 
-/**int jbd2_journal_force_commit() - force any uncommitted transactions
+/**
+ * int jbd2_journal_force_commit() - force any uncommitted transactions
  * @journal: journal to force
  *
  * For synchronous operations: force any uncommitted transactions
@@ -2077,7 +2106,7 @@ void __jbd2_journal_refile_buffer(struct journal_head *jh)
         jh->b_transaction = jh->b_next_transaction;
         jh->b_next_transaction = NULL;
         __jbd2_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)