// SPDX-License-Identifier: GPL-2.0-or-later/* Unbuffered and direct write support. * * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #include <linux/export.h>#include <linux/uio.h>#include "internal.h" /* * Perform the cleanup rituals after an unbuffered write is complete. */static void netfs_unbuffered_write_done(struct netfs_io_request *wreq){	struct netfs_inode *ictx = netfs_inode(wreq->inode); 	_enter("R=%x", wreq->debug_id); 	/* Okay, declare that all I/O is complete. */	trace_netfs_rreq(wreq, netfs_rreq_trace_write_done); 	if (wreq->transferred)		netfs_update_i_size(ictx, &ictx->inode, wreq->start, wreq->transferred); 	if (wreq->origin == NETFS_DIO_WRITE &&	    wreq->mapping->nrpages) {		/* mmap may have got underfoot and we may now have folios		 * locally covering the region we just wrote.  Attempt to		 * discard the folios, but leave in place any modified locally.		 * ->write_iter() is prevented from interfering by the DIO		 * counter.		 */		pgoff_t first = wreq->start >> PAGE_SHIFT;		pgoff_t last = (wreq->start + wreq->transferred - 1) >> PAGE_SHIFT; 		invalidate_inode_pages2_range(wreq->mapping, first, last);	} 	if (wreq->origin == NETFS_DIO_WRITE)		inode_dio_end(wreq->inode); 	_debug("finished");	netfs_wake_rreq_flag(wreq, NETFS_RREQ_IN_PROGRESS, netfs_rreq_trace_wake_ip);	/* As we cleared NETFS_RREQ_IN_PROGRESS, we acquired its ref. */ 	if (wreq->iocb) {		size_t written = umin(wreq->transferred, wreq->len); 		wreq->iocb->ki_pos += written;		if (wreq->iocb->ki_complete) {			trace_netfs_rreq(wreq, netfs_rreq_trace_ki_complete);			wreq->iocb->ki_complete(wreq->iocb, written ?: wreq->error);		}		wreq->iocb = VFS_PTR_POISON;	} 	netfs_clear_subrequests(wreq);} /* * Collect the subrequest results of unbuffered write subrequests. */static void netfs_unbuffered_write_collect(struct netfs_io_request *wreq,					   struct netfs_io_stream *stream,					   struct netfs_io_subrequest *subreq){	trace_netfs_collect_sreq(wreq, subreq); 	spin_lock(&wreq->lock);	list_del_init(&subreq->rreq_link);	spin_unlock(&wreq->lock); 	wreq->transferred += subreq->transferred;	iov_iter_advance(&wreq->buffer.iter, subreq->transferred); 	stream->collected_to = subreq->start + subreq->transferred;	wreq->collected_to = stream->collected_to;	netfs_put_subrequest(subreq, netfs_sreq_trace_put_done); 	trace_netfs_collect_stream(wreq, stream);	trace_netfs_collect_state(wreq, wreq->collected_to, 0);} /* * Write data to the server without going through the pagecache and without * writing it to the local cache.  We dispatch the subrequests serially and * wait for each to complete before dispatching the next, lest we leave a gap * in the data written due to a failure such as ENOSPC.  We could, however * attempt to do preparation such as content encryption for the next subreq * whilst the current is in progress. */static int netfs_unbuffered_write(struct netfs_io_request *wreq){	struct netfs_io_subrequest *subreq = NULL;	struct netfs_io_stream *stream = &wreq->io_streams[0];	int ret = 0; 	_enter("%llx", wreq->len); 	if (wreq->origin == NETFS_DIO_WRITE)		inode_dio_begin(wreq->inode); 	stream->collected_to = wreq->start; 	for (;;) {		bool retry = false; 		if (!subreq) {			netfs_prepare_write(wreq, stream, wreq->start + wreq->transferred);			subreq = stream->construct;			if (!subreq) {				wreq->error = -ENOMEM;				ret = -ENOMEM;				break;			}			stream->construct = NULL;		} 		/* Check if (re-)preparation failed. */		if (unlikely(test_bit(NETFS_SREQ_FAILED, &subreq->flags))) {			netfs_write_subrequest_terminated(subreq, subreq->error);			wreq->error = subreq->error;			break;		} 		iov_iter_truncate(&subreq->io_iter, wreq->len - wreq->transferred);		if (!iov_iter_count(&subreq->io_iter)) {			pr_warn("netfs: Unexpected zero-length iterator R=%08x\n",				wreq->debug_id);			__set_bit(NETFS_SREQ_FAILED, &subreq->flags);			netfs_write_subrequest_terminated(subreq, -EIO);			wreq->error = -EIO;			break;		} 		subreq->len = netfs_limit_iter(&subreq->io_iter, 0,					       stream->sreq_max_len,					       stream->sreq_max_segs);		iov_iter_truncate(&subreq->io_iter, subreq->len);		stream->submit_extendable_to = subreq->len; 		trace_netfs_sreq(subreq, netfs_sreq_trace_submit);		stream->issue_write(subreq); 		/* Async, need to wait. */		netfs_wait_for_in_progress_stream(wreq, stream); 		if (test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) {			retry = true;		} else if (test_bit(NETFS_SREQ_FAILED, &subreq->flags)) {			wreq->error = subreq->error;			netfs_see_subrequest(subreq, netfs_sreq_trace_see_failed);			subreq = NULL;			break;		} 		if (!retry) {			netfs_unbuffered_write_collect(wreq, stream, subreq);			subreq = NULL;			if (wreq->transferred >= wreq->len)				break;			if (!wreq->iocb && signal_pending(current)) {				ret = wreq->transferred ? -EINTR : -ERESTARTSYS;				trace_netfs_rreq(wreq, netfs_rreq_trace_intr);				break;			}			continue;		} 		/* We need to retry the last subrequest, so first reset the		 * iterator, taking into account what, if anything, we managed		 * to transfer.		 */		subreq->error = -EAGAIN;		trace_netfs_sreq(subreq, netfs_sreq_trace_retry);		if (subreq->transferred > 0) {			iov_iter_advance(&wreq->buffer.iter, subreq->transferred);			wreq->transferred += subreq->transferred;		} 		if (stream->source == NETFS_UPLOAD_TO_SERVER &&		    wreq->netfs_ops->retry_request)			wreq->netfs_ops->retry_request(wreq, stream); 		__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);		__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);		__clear_bit(NETFS_SREQ_BOUNDARY, &subreq->flags);		__clear_bit(NETFS_SREQ_FAILED, &subreq->flags);		subreq->io_iter		= wreq->buffer.iter;		subreq->start		= wreq->start + wreq->transferred;		subreq->len		= wreq->len   - wreq->transferred;		subreq->transferred	= 0;		subreq->retry_count	+= 1;		stream->sreq_max_len	= UINT_MAX;		stream->sreq_max_segs	= INT_MAX; 		netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit); 		if (stream->prepare_write)			stream->prepare_write(subreq);		__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);		netfs_stat(&netfs_n_wh_retry_write_subreq);	} 	netfs_unbuffered_write_done(wreq);	_leave(" = %d", ret);	return ret;} static void netfs_unbuffered_write_async(struct work_struct *work){	struct netfs_io_request *wreq = container_of(work, struct netfs_io_request, work); 	netfs_unbuffered_write(wreq);	netfs_put_request(wreq, netfs_rreq_trace_put_complete);} /* * Perform an unbuffered write where we may have to do an RMW operation on an * encrypted file.  This can also be used for direct I/O writes. */ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,						  struct netfs_group *netfs_group){	struct netfs_io_request *wreq;	unsigned long long start = iocb->ki_pos;	unsigned long long end = start + iov_iter_count(iter);	ssize_t ret, n;	size_t len = iov_iter_count(iter);	bool async = !is_sync_kiocb(iocb); 	_enter(""); 	/* We're going to need a bounce buffer if what we transmit is going to	 * be different in some way to the source buffer, e.g. because it gets	 * encrypted/compressed or because it needs expanding to a block size.	 */	// TODO 	_debug("uw %llx-%llx", start, end); 	wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp, start,				      iocb->ki_flags & IOCB_DIRECT ?				      NETFS_DIO_WRITE : NETFS_UNBUFFERED_WRITE);	if (IS_ERR(wreq))		return PTR_ERR(wreq); 	wreq->io_streams[0].avail = true;	trace_netfs_write(wreq, (iocb->ki_flags & IOCB_DIRECT ?				 netfs_write_trace_dio_write :				 netfs_write_trace_unbuffered_write)); 	{		/* If this is an async op and we're not using a bounce buffer,		 * we have to save the source buffer as the iterator is only		 * good until we return.  In such a case, extract an iterator		 * to represent as much of the the output buffer as we can		 * manage.  Note that the extraction might not be able to		 * allocate a sufficiently large bvec array and may shorten the		 * request.		 */		if (user_backed_iter(iter)) {			n = netfs_extract_user_iter(iter, len, &wreq->buffer.iter, 0);			if (n < 0) {				ret = n;				goto error_put;			}			wreq->direct_bv = (struct bio_vec *)wreq->buffer.iter.bvec;			wreq->direct_bv_count = n;			wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter);		} else {			/* If this is a kernel-generated async DIO request,			 * assume that any resources the iterator points to			 * (eg. a bio_vec array) will persist till the end of			 * the op.			 */			wreq->buffer.iter = *iter;		} 		wreq->len = iov_iter_count(&wreq->buffer.iter);	} 	__set_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags); 	/* Copy the data into the bounce buffer and encrypt it. */	// TODO 	/* Dispatch the write. */	__set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags); 	if (async) {		INIT_WORK(&wreq->work, netfs_unbuffered_write_async);		wreq->iocb = iocb;		queue_work(system_dfl_wq, &wreq->work);		ret = -EIOCBQUEUED;	} else {		ret = netfs_unbuffered_write(wreq);		if (wreq->transferred) {			iocb->ki_pos += wreq->transferred;			ret = wreq->transferred;		} else if (wreq->error) {			ret = wreq->error;		} 		netfs_put_request(wreq, netfs_rreq_trace_put_complete);	} 	netfs_put_request(wreq, netfs_rreq_trace_put_return);	return ret; error_put:	netfs_put_failed_request(wreq);	return ret;}EXPORT_SYMBOL(netfs_unbuffered_write_iter_locked); /** * netfs_unbuffered_write_iter - Unbuffered write to a file * @iocb: IO state structure * @from: iov_iter with data to write * * Do an unbuffered write to a file, writing the data directly to the server * and not lodging the data in the pagecache. * * Return: * * Negative error code if no data has been written at all of *   vfs_fsync_range() failed for a synchronous write * * Number of bytes written, even for truncated writes */ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from){	struct file *file = iocb->ki_filp;	struct address_space *mapping = file->f_mapping;	struct inode *inode = mapping->host;	struct netfs_inode *ictx = netfs_inode(inode);	ssize_t ret;	loff_t pos = iocb->ki_pos;	unsigned long long end = pos + iov_iter_count(from) - 1; 	_enter("%llx,%zx,%llx", pos, iov_iter_count(from), i_size_read(inode)); 	if (!iov_iter_count(from))		return 0; 	trace_netfs_write_iter(iocb, from);	netfs_stat(&netfs_n_wh_dio_write); 	ret = netfs_start_io_direct(inode);	if (ret < 0)		return ret;	ret = generic_write_checks(iocb, from);	if (ret <= 0)		goto out;	ret = file_remove_privs(file);	if (ret < 0)		goto out;	ret = file_update_time(file);	if (ret < 0)		goto out;	if (iocb->ki_flags & IOCB_NOWAIT) {		/* We could block if there are any pages in the range. */		ret = -EAGAIN;		if (filemap_range_has_page(mapping, pos, end))			if (filemap_invalidate_inode(inode, true, pos, end))				goto out;	} else {		ret = filemap_write_and_wait_range(mapping, pos, end);		if (ret < 0)			goto out;	} 	/*	 * After a write we want buffered reads to be sure to go to disk to get	 * the new data.  We invalidate clean cached page from the region we're	 * about to write.  We do this *before* the write so that we can return	 * without clobbering -EIOCBQUEUED from ->direct_IO().	 */	ret = filemap_invalidate_inode(inode, true, pos, end);	if (ret < 0)		goto out;	end = iocb->ki_pos + iov_iter_count(from);	spin_lock(&inode->i_lock);	if (end > ictx->_zero_point)		netfs_write_zero_point(inode, end);	spin_unlock(&inode->i_lock); 	fscache_invalidate(netfs_i_cookie(ictx), NULL, i_size_read(inode),			   FSCACHE_INVAL_DIO_WRITE);	ret = netfs_unbuffered_write_iter_locked(iocb, from, NULL);out:	netfs_end_io_direct(inode);	return ret;}EXPORT_SYMBOL(netfs_unbuffered_write_iter);