int ntfs_writepage (struct page * page, struct writeback_control * wbc);
For non-resident attributes, ntfs_writepage writes the page by calling the ntfs version of the generic block_write_full_page function, ntfs_write_block, which in turn if necessary creates and writes the buffers associated with the page asynchronously.
For resident attributes, OTOH, ntfs_writepage writes the page by copying the data to the mft record (which at this stage is most likely in memory). Thus, in this case, I/O is synchronous, as even if the mft record is not cached at this point in time, we need to wait for it to be read in before we can do the copy.
Note the caller clears the page dirty flag before calling ntfs_writepage.
Based on ntfs_readpage and fs/buffer.c::block_write_full_page.
Return 0 on success and -errno on error.