5 files changed, 114 insertions, 0 deletions

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index ebc667bc54a8..c8a1bace685a 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -509,6 +509,10 @@ void jbd2_journal_commit_transaction(journal_t *journal)
                 if (is_journal_aborted(journal)) {
                         clear_buffer_jbddirty(jh2bh(jh));
                         JBUFFER_TRACE(jh, "journal is aborting: refile");
+                        jbd2_buffer_abort_trigger(jh,
+                                                  jh->b_frozen_data ?
+                                                  jh->b_frozen_triggers :
+                                                  jh->b_triggers);
                         jbd2_journal_refile_buffer(journal, jh);
                         /* If that was the last one, we need to clean up
                          * any descriptor buffers which may have been
@@ -844,6 +848,9 @@ restart_loop:
                  * data.
                  *
                  * Otherwise, we can just throw away the frozen data now.
+                 *
+                 * We also know that the frozen data has already fired
+                 * its triggers if they exist, so we can clear that too.
                  */
                 if (jh->b_committed_data) {
                         jbd2_free(jh->b_committed_data, bh->b_size);
@@ -851,10 +858,12 @@ restart_loop:
                         if (jh->b_frozen_data) {
                                 jh->b_committed_data = jh->b_frozen_data;
                                 jh->b_frozen_data = NULL;
+                                jh->b_frozen_triggers = NULL;
                         }
                 } else if (jh->b_frozen_data) {
                         jbd2_free(jh->b_frozen_data, bh->b_size);
                         jh->b_frozen_data = NULL;
+                        jh->b_frozen_triggers = NULL;
                 }
 
                 spin_lock(&journal->j_list_lock);
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index e70d657a19f8..f6bff9d6f8df 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -50,6 +50,7 @@ EXPORT_SYMBOL(jbd2_journal_unlock_updates);
 EXPORT_SYMBOL(jbd2_journal_get_write_access);
 EXPORT_SYMBOL(jbd2_journal_get_create_access);
 EXPORT_SYMBOL(jbd2_journal_get_undo_access);
+EXPORT_SYMBOL(jbd2_journal_set_triggers);
 EXPORT_SYMBOL(jbd2_journal_dirty_metadata);
 EXPORT_SYMBOL(jbd2_journal_release_buffer);
 EXPORT_SYMBOL(jbd2_journal_forget);
@@ -290,6 +291,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
         struct page *new_page;
         unsigned int new_offset;
         struct buffer_head *bh_in = jh2bh(jh_in);
+        struct jbd2_buffer_trigger_type *triggers;
 
         /*
          * The buffer really shouldn't be locked: only the current committing
@@ -314,13 +316,23 @@ repeat:
                 done_copy_out = 1;
                 new_page = virt_to_page(jh_in->b_frozen_data);
                 new_offset = offset_in_page(jh_in->b_frozen_data);
+                triggers = jh_in->b_frozen_triggers;
         } else {
                 new_page = jh2bh(jh_in)->b_page;
                 new_offset = offset_in_page(jh2bh(jh_in)->b_data);
+                triggers = jh_in->b_triggers;
         }
 
         mapped_data = kmap_atomic(new_page, KM_USER0);
         /*
+         * Fire any commit trigger.  Do this before checking for escaping,
+         * as the trigger may modify the magic offset.  If a copy-out
+         * happens afterwards, it will have the correct data in the buffer.
+         */
+        jbd2_buffer_commit_trigger(jh_in, mapped_data + new_offset,
+                                   triggers);
+
+        /*
          * Check for escaping
          */
         if (*((__be32 *)(mapped_data + new_offset)) ==
@@ -352,6 +364,13 @@ repeat:
                 new_page = virt_to_page(tmp);
                 new_offset = offset_in_page(tmp);
                 done_copy_out = 1;
+
+                /*
+                 * This isn't strictly necessary, as we're using frozen
+                 * data for the escaping, but it keeps consistency with
+                 * b_frozen_data usage.
+                 */
+                jh_in->b_frozen_triggers = jh_in->b_triggers;
         }
 
         /*
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 39b7805a599a..4f925a4f3d05 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -741,6 +741,12 @@ done:
                 source = kmap_atomic(page, KM_USER0);
                 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
                 kunmap_atomic(source, KM_USER0);
+
+                /*
+                 * Now that the frozen data is saved off, we need to store
+                 * any matching triggers.
+                 */
+                jh->b_frozen_triggers = jh->b_triggers;
         }
         jbd_unlock_bh_state(bh);
 
@@ -944,6 +950,47 @@ out:
 }
 
 /**
+ * void jbd2_journal_set_triggers() - Add triggers for commit writeout
+ * @bh: buffer to trigger on
+ * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
+ *
+ * Set any triggers on this journal_head.  This is always safe, because
+ * triggers for a committing buffer will be saved off, and triggers for
+ * a running transaction will match the buffer in that transaction.
+ *
+ * Call with NULL to clear the triggers.
+ */
+void jbd2_journal_set_triggers(struct buffer_head *bh,
+                               struct jbd2_buffer_trigger_type *type)
+{
+        struct journal_head *jh = bh2jh(bh);
+
+        jh->b_triggers = type;
+}
+
+void jbd2_buffer_commit_trigger(struct journal_head *jh, void *mapped_data,
+                                struct jbd2_buffer_trigger_type *triggers)
+{
+        struct buffer_head *bh = jh2bh(jh);
+
+        if (!triggers || !triggers->t_commit)
+                return;
+
+        triggers->t_commit(triggers, bh, mapped_data, bh->b_size);
+}
+
+void jbd2_buffer_abort_trigger(struct journal_head *jh,
+                               struct jbd2_buffer_trigger_type *triggers)
+{
+        if (!triggers || !triggers->t_abort)
+                return;
+
+        triggers->t_abort(triggers, jh2bh(jh));
+}
+
+
+
+/**
  * int jbd2_journal_dirty_metadata() -  mark a buffer as containing dirty metadata
  * @handle: transaction to add buffer to.
  * @bh: buffer to mark
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index f36645745489..34456476e761 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1008,6 +1008,35 @@ int __jbd2_journal_clean_checkpoint_list(journal_t *journal);
 int __jbd2_journal_remove_checkpoint(struct journal_head *);
 void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
 
+
+/*
+ * Triggers
+ */
+
+struct jbd2_buffer_trigger_type {
+        /*
+         * Fired just before a buffer is written to the journal.
+         * mapped_data is a mapped buffer that is the frozen data for
+         * commit.
+         */
+        void (*t_commit)(struct jbd2_buffer_trigger_type *type,
+                         struct buffer_head *bh, void *mapped_data,
+                         size_t size);
+
+        /*
+         * Fired during journal abort for dirty buffers that will not be
+         * committed.
+         */
+        void (*t_abort)(struct jbd2_buffer_trigger_type *type,
+                        struct buffer_head *bh);
+};
+
+extern void jbd2_buffer_commit_trigger(struct journal_head *jh,
+                                       void *mapped_data,
+                                       struct jbd2_buffer_trigger_type *triggers);
+extern void jbd2_buffer_abort_trigger(struct journal_head *jh,
+                                      struct jbd2_buffer_trigger_type *triggers);
+
 /* Buffer IO */
 extern int
 jbd2_journal_write_metadata_buffer(transaction_t          *transaction,
@@ -1046,6 +1075,8 @@ extern int	 jbd2_journal_extend (handle_t *, int nblocks);
 extern int       jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
 extern int       jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
 extern int       jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
+void             jbd2_journal_set_triggers(struct buffer_head *,
+                                           struct jbd2_buffer_trigger_type *type);
 extern int       jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *);
 extern void      jbd2_journal_release_buffer (handle_t *, struct buffer_head *);
 extern int       jbd2_journal_forget (handle_t *, struct buffer_head *);
diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h
index bb70ebb6a2d5..525aac3c97df 100644
--- a/include/linux/journal-head.h
+++ b/include/linux/journal-head.h
@@ -12,6 +12,8 @@
 
 typedef unsigned int            tid_t;          /* Unique transaction ID */
 typedef struct transaction_s    transaction_t;  /* Compound transaction type */
+
+
 struct buffer_head;
 
 struct journal_head {
@@ -87,6 +89,12 @@ struct journal_head {
          * [j_list_lock]
          */
         struct journal_head *b_cpnext, *b_cpprev;
+
+        /* Trigger type */
+        struct jbd2_buffer_trigger_type *b_triggers;
+
+        /* Trigger type for the committing transaction's frozen data */
+        struct jbd2_buffer_trigger_type *b_frozen_triggers;
 };
 
 #endif          /* JOURNAL_HEAD_H_INCLUDED */