jbd2: Implement data=ordered mode handling via inodes

This patch adds necessary framework into JBD2 to be able to track inodes
with each transaction and write-out their dirty data during transaction
commit time.

This new ordered mode brings all sorts of advantages such as possibility 
to get rid of journal heads and buffer heads for data buffers in ordered 
mode, better ordering of writes on transaction commit, simplification of
 some JBD code, no more anonymous pages when truncate of data being 
committed happens.  Also with this new ordered mode, delayed allocation 
on ordered mode is much simpler.

Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 90 insertions, 0 deletions

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 92b6ac3df8a..3ca107b5c86 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -355,6 +355,81 @@ write_out_data:
 	journal_do_submit_data(wbuf, bufs);
 }
 
+/*
+ * Submit all the data buffers of inode associated with the transaction to
+ * disk.
+ *
+ * We are in a committing transaction. Therefore no new inode can be added to
+ * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently
+ * operate on from being released while we write out pages.
+ */
+static int journal_submit_inode_data_buffers(journal_t *journal,
+		transaction_t *commit_transaction)
+{
+	struct jbd2_inode *jinode;
+	int err, ret = 0;
+	struct address_space *mapping;
+
+	spin_lock(&journal->j_list_lock);
+	list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
+		mapping = jinode->i_vfs_inode->i_mapping;
+		jinode->i_flags |= JI_COMMIT_RUNNING;
+		spin_unlock(&journal->j_list_lock);
+		err = filemap_fdatawrite_range(mapping, 0,
+					i_size_read(jinode->i_vfs_inode));
+		if (!ret)
+			ret = err;
+		spin_lock(&journal->j_list_lock);
+		J_ASSERT(jinode->i_transaction == commit_transaction);
+		jinode->i_flags &= ~JI_COMMIT_RUNNING;
+		wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
+	}
+	spin_unlock(&journal->j_list_lock);
+	return ret;
+}
+
+/*
+ * Wait for data submitted for writeout, refile inodes to proper
+ * transaction if needed.
+ *
+ */
+static int journal_finish_inode_data_buffers(journal_t *journal,
+		transaction_t *commit_transaction)
+{
+	struct jbd2_inode *jinode, *next_i;
+	int err, ret = 0;
+
+	/* For locking, see the comment in journal_submit_inode_data_buffers() */
+	spin_lock(&journal->j_list_lock);
+	list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
+		jinode->i_flags |= JI_COMMIT_RUNNING;
+		spin_unlock(&journal->j_list_lock);
+		err = filemap_fdatawait(jinode->i_vfs_inode->i_mapping);
+		if (!ret)
+			ret = err;
+		spin_lock(&journal->j_list_lock);
+		jinode->i_flags &= ~JI_COMMIT_RUNNING;
+		wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
+	}
+
+	/* Now refile inode to proper lists */
+	list_for_each_entry_safe(jinode, next_i,
+				 &commit_transaction->t_inode_list, i_list) {
+		list_del(&jinode->i_list);
+		if (jinode->i_next_transaction) {
+			jinode->i_transaction = jinode->i_next_transaction;
+			jinode->i_next_transaction = NULL;
+			list_add(&jinode->i_list,
+				&jinode->i_transaction->t_inode_list);
+		} else {
+			jinode->i_transaction = NULL;
+		}
+	}
+	spin_unlock(&journal->j_list_lock);
+
+	return ret;
+}
+
 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 {
 	struct page *page = bh->b_page;
@@ -529,6 +604,9 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	 */
 	err = 0;
 	journal_submit_data_buffers(journal, commit_transaction);
+	err = journal_submit_inode_data_buffers(journal, commit_transaction);
+	if (err)
+		jbd2_journal_abort(journal, err);
 
 	/*
 	 * Wait for all previously submitted IO to complete if commit
@@ -760,6 +838,17 @@ start_journal_io:
 			__jbd2_journal_abort_hard(journal);
 	}
 
+	/*
+	 * This is the right place to wait for data buffers both for ASYNC
+	 * and !ASYNC commit. If commit is ASYNC, we need to wait only after
+	 * the commit block went to disk (which happens above). If commit is
+	 * SYNC, we need to wait for data buffers before we start writing
+	 * commit block, which happens below in such setting.
+	 */
+	err = journal_finish_inode_data_buffers(journal, commit_transaction);
+	if (err)
+		jbd2_journal_abort(journal, err);
+
 	/* Lo and behold: we have just managed to send a transaction to
            the log.  Before we can commit it, wait for the IO so far to
            complete.  Control buffers being written are on the
@@ -880,6 +969,7 @@ wait_for_iobuf:
 	jbd_debug(3, "JBD: commit phase 7\n");
 
 	J_ASSERT(commit_transaction->t_sync_datalist == NULL);
+	J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 	J_ASSERT(commit_transaction->t_buffers == NULL);
 	J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 	J_ASSERT(commit_transaction->t_iobuf_list == NULL);