This implements the journal's j_submit_inode_data_buffers() callback
to write-protect the inode's pages with write_cache_pages(), and use
a writepage callback to redirty pages with buffers that are not part
of the committing transaction or the next transaction.
And set a no-op function as j_finish_inode_data_buffers() callback
(nothing needed other than the write-protect above.)
Currently, the inode is added to the transaction's inode list in the
__ext4_journalled_writepage() function.
---
fs/ext4/inode.c | 4 +++
fs/ext4/super.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 69 insertions(+)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 10dd470876b3..978ccde8454f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1911,6 +1911,10 @@ static int __ext4_journalled_writepage(struct page *page,
err = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
write_end_fn);
}
+ if (ret == 0)
+ ret = err;
+ // XXX: is this correct for inline data inodes?
+ err = ext4_jbd2_inode_add_write(handle, inode, 0, len);
if (ret == 0)
ret = err;
EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 330957ed1f05..38aaac6572ea 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -472,6 +472,66 @@ static void ext4_journal_commit_callback(journal_t *journal, transaction_t *txn)
spin_unlock(&sbi->s_md_lock);
}
+/*
+ * This writepage callback for write_cache_pages()
+ * takes care of a few cases after page cleaning.
+ *
+ * write_cache_pages() already checks for dirty pages
+ * and calls clear_page_dirty_for_io(), which we want,
+ * to write protect the pages.
+ *
+ * However, we have to redirty a page in two cases:
+ * 1) some buffer is not part of the committing transaction
+ * 2) some buffer already has b_next_transaction set
+ */
+
+static int ext4_journalled_writepage_callback(struct page *page,
+ struct writeback_control *wbc,
+ void *data)
+{
+ transaction_t *transaction = (transaction_t *) data;
+ struct buffer_head *bh, *head;
+ struct journal_head *jh;
+
+ // XXX: any chance of !bh here?
+ bh = head = page_buffers(page);
+ do {
+ jh = bh2jh(bh);
+ if (!jh || jh->b_transaction != transaction ||
+ jh->b_next_transaction) {
+ redirty_page_for_writepage(wbc, page);
+ goto out;
+ }
+ } while ((bh = bh->b_this_page) != head);
+
+out:
+ return AOP_WRITEPAGE_ACTIVATE;
+}
+
+static int ext4_journalled_submit_inode_data_buffers(struct jbd2_inode *jinode)
+{
+ struct address_space *mapping = jinode->i_vfs_inode->i_mapping;
+ transaction_t *transaction = jinode->i_transaction;
+ loff_t dirty_start = jinode->i_dirty_start;
+ loff_t dirty_end = jinode->i_dirty_end;
+
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_ALL,
+ .nr_to_write = mapping->nrpages * 2,
+ .range_start = dirty_start,
+ .range_end = dirty_end,
+ };
+
+ return write_cache_pages(mapping, &wbc,
+ ext4_journalled_writepage_callback,
+ transaction);
+}
+
+static int ext4_journalled_finish_inode_data_buffers(struct jbd2_inode *jinode)
+{
+ return 0;
+}
+
static bool system_going_down(void)
{
return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
@@ -4599,6 +4659,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
ext4_msg(sb, KERN_ERR, "can't mount with "
"journal_async_commit in data=ordered mode");
goto failed_mount_wq;
+ } else if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) {
+ sbi->s_journal->j_submit_inode_data_buffers =
+ ext4_journalled_submit_inode_data_buffers;
+ sbi->s_journal->j_finish_inode_data_buffers =
+ ext4_journalled_finish_inode_data_buffers;
}
set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
--
2.17.1
