netfs: Cut over to using new writeback code

Cut over to using the new writeback code.  The old code is #ifdef'd out or
otherwise removed from compilation to avoid conflicts and will be removed
in a future patch.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Eric Van Hensbergen <ericvh@kernel.org>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Christian Schoenebeck <linux_oss@crudebyte.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: v9fs@lists.linux.dev
cc: linux-afs@lists.infradead.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org

fs/9p/vfs_addr.c

@@ -60,6 +60,7 @@ static void v9fs_issue_write(struct netfs_io_subrequest *subreq)
 	netfs_write_subrequest_terminated(subreq, len ?: err, false);
 }
 
+#if 0 // TODO: Remove
 static void v9fs_upload_to_server(struct netfs_io_subrequest *subreq)
 {
 	struct p9_fid *fid = subreq->rreq->netfs_priv;
@@ -91,6 +92,7 @@ static void v9fs_create_write_requests(struct netfs_io_request *wreq, loff_t sta
 	if (subreq)
 		netfs_queue_write_request(subreq);
 }
+#endif
 
 /**
  * v9fs_issue_read - Issue a read from 9P
@@ -121,18 +123,15 @@ static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
 {
 	struct p9_fid *fid;
 	bool writing = (rreq->origin == NETFS_READ_FOR_WRITE ||
-			rreq->origin == NETFS_WRITEBACK ||
 			rreq->origin == NETFS_WRITETHROUGH ||
 			rreq->origin == NETFS_UNBUFFERED_WRITE ||
 			rreq->origin == NETFS_DIO_WRITE);
 
-#if 0 // TODO: Cut over
 	if (rreq->origin == NETFS_WRITEBACK)
 		return 0; /* We don't get the write handle until we find we
 			   * have actually dirty data and not just
 			   * copy-to-cache data.
 			   */
-#endif
 
 	if (file) {
 		fid = file->private_data;
@@ -179,7 +178,6 @@ const struct netfs_request_ops v9fs_req_ops = {
 	.issue_read		= v9fs_issue_read,
 	.begin_writeback	= v9fs_begin_writeback,
 	.issue_write		= v9fs_issue_write,
-	.create_write_requests	= v9fs_create_write_requests,
 };
 
 const struct address_space_operations v9fs_addr_operations = {

fs/afs/file.c

@@ -353,7 +353,7 @@ static int afs_init_request(struct netfs_io_request *rreq, struct file *file)
 	if (file)
 		rreq->netfs_priv = key_get(afs_file_key(file));
 	rreq->rsize = 256 * 1024;
-	rreq->wsize = 256 * 1024;
+	rreq->wsize = 256 * 1024 * 1024;
 	return 0;
 }
 
@@ -399,7 +399,6 @@ const struct netfs_request_ops afs_req_ops = {
 	.issue_read		= afs_issue_read,
 	.update_i_size		= afs_update_i_size,
 	.invalidate_cache	= afs_netfs_invalidate_cache,
-	.create_write_requests	= afs_create_write_requests,
 	.begin_writeback	= afs_begin_writeback,
 	.prepare_write		= afs_prepare_write,
 	.issue_write		= afs_issue_write,

fs/afs/internal.h

@@ -1605,7 +1605,6 @@ extern int afs_writepages(struct address_space *, struct writeback_control *);
 extern int afs_fsync(struct file *, loff_t, loff_t, int);
 extern vm_fault_t afs_page_mkwrite(struct vm_fault *vmf);
 extern void afs_prune_wb_keys(struct afs_vnode *);
-void afs_create_write_requests(struct netfs_io_request *wreq, loff_t start, size_t len);
 
 /*
  * xattr.c

fs/afs/write.c

@@ -156,6 +156,7 @@ static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t
 	return afs_put_operation(op);
 }
 
+#if 0 // TODO: Remove
 static void afs_upload_to_server(struct netfs_io_subrequest *subreq)
 {
 	struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
@@ -193,6 +194,7 @@ void afs_create_write_requests(struct netfs_io_request *wreq, loff_t start, size
 	if (subreq)
 		netfs_queue_write_request(subreq);
 }
+#endif
 
 /*
  * Writeback calls this when it finds a folio that needs uploading.  This isn't

fs/netfs/Makefile

@@ -11,7 +11,6 @@ netfs-y := \
 	main.o \
 	misc.o \
 	objects.o \
-	output.o \
 	write_collect.o \
 	write_issue.o
 

fs/netfs/buffered_write.c

@@ -26,8 +26,6 @@ enum netfs_how_to_modify {
 	NETFS_FLUSH_CONTENT,		/* Flush incompatible content. */
 };
 
-static void netfs_cleanup_buffered_write(struct netfs_io_request *wreq);
-
 static void netfs_set_group(struct folio *folio, struct netfs_group *netfs_group)
 {
 	void *priv = folio_get_private(folio);
@@ -180,7 +178,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 	};
 	struct netfs_io_request *wreq = NULL;
 	struct netfs_folio *finfo;
-	struct folio *folio;
+	struct folio *folio, *writethrough = NULL;
 	enum netfs_how_to_modify howto;
 	enum netfs_folio_trace trace;
 	unsigned int bdp_flags = (iocb->ki_flags & IOCB_SYNC) ? 0: BDP_ASYNC;
@@ -209,7 +207,6 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 		}
 		if (!is_sync_kiocb(iocb))
 			wreq->iocb = iocb;
-		wreq->cleanup = netfs_cleanup_buffered_write;
 		netfs_stat(&netfs_n_wh_writethrough);
 	} else {
 		netfs_stat(&netfs_n_wh_buffered_write);
@@ -253,6 +250,16 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 		offset = pos & (flen - 1);
 		part = min_t(size_t, flen - offset, part);
 
+		/* Wait for writeback to complete.  The writeback engine owns
+		 * the info in folio->private and may change it until it
+		 * removes the WB mark.
+		 */
+		if (folio_get_private(folio) &&
+		    folio_wait_writeback_killable(folio)) {
+			ret = written ? -EINTR : -ERESTARTSYS;
+			goto error_folio_unlock;
+		}
+
 		if (signal_pending(current)) {
 			ret = written ? -EINTR : -ERESTARTSYS;
 			goto error_folio_unlock;
@@ -327,6 +334,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 				maybe_trouble = true;
 				iov_iter_revert(iter, copied);
 				copied = 0;
+				folio_unlock(folio);
 				goto retry;
 			}
 			netfs_set_group(folio, netfs_group);
@@ -382,23 +390,14 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 
 		if (likely(!wreq)) {
 			folio_mark_dirty(folio);
+			folio_unlock(folio);
 		} else {
-			if (folio_test_dirty(folio))
-				/* Sigh.  mmap. */
-				folio_clear_dirty_for_io(folio);
-			/* We make multiple writes to the folio... */
-			if (!folio_test_writeback(folio)) {
-				folio_start_writeback(folio);
-				if (wreq->iter.count == 0)
-					trace_netfs_folio(folio, netfs_folio_trace_wthru);
-				else
-					trace_netfs_folio(folio, netfs_folio_trace_wthru_plus);
-			}
-			netfs_advance_writethrough(wreq, copied,
-						   offset + copied == flen);
+			netfs_advance_writethrough(wreq, &wbc, folio, copied,
+						   offset + copied == flen,
+						   &writethrough);
+			/* Folio unlocked */
 		}
 	retry:
-		folio_unlock(folio);
 		folio_put(folio);
 		folio = NULL;
 
@@ -407,7 +406,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 
 out:
 	if (unlikely(wreq)) {
-		ret2 = netfs_end_writethrough(wreq, iocb);
+		ret2 = netfs_end_writethrough(wreq, &wbc, writethrough);
 		wbc_detach_inode(&wbc);
 		if (ret2 == -EIOCBQUEUED)
 			return ret2;
@@ -529,11 +528,13 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr
 
 	sb_start_pagefault(inode->i_sb);
 
-	if (folio_wait_writeback_killable(folio))
+	if (folio_lock_killable(folio) < 0)
 		goto out;
 
-	if (folio_lock_killable(folio) < 0)
+	if (folio_wait_writeback_killable(folio)) {
+		ret = VM_FAULT_LOCKED;
 		goto out;
+	}
 
 	/* Can we see a streaming write here? */
 	if (WARN_ON(!folio_test_uptodate(folio))) {
@@ -573,6 +574,7 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr
 }
 EXPORT_SYMBOL(netfs_page_mkwrite);
 
+#if 0 // TODO: Remove
 /*
  * Kill all the pages in the given range
  */
@@ -1199,3 +1201,4 @@ int netfs_writepages(struct address_space *mapping,
 	return ret;
 }
 EXPORT_SYMBOL(netfs_writepages);
+#endif

fs/netfs/direct_write.c

@@ -34,6 +34,7 @@ static ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov
 	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("");
@@ -46,13 +47,17 @@ static ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov
 
 	_debug("uw %llx-%llx", start, end);
 
-	wreq = netfs_alloc_request(iocb->ki_filp->f_mapping, iocb->ki_filp,
-				   start, end - start,
-				   iocb->ki_flags & IOCB_DIRECT ?
-				   NETFS_DIO_WRITE : NETFS_UNBUFFERED_WRITE);
+	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
@@ -63,22 +68,23 @@ static ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov
 		 * request.
 		 */
 		if (async || user_backed_iter(iter)) {
-			n = netfs_extract_user_iter(iter, wreq->len, &wreq->iter, 0);
+			n = netfs_extract_user_iter(iter, len, &wreq->iter, 0);
 			if (n < 0) {
 				ret = n;
 				goto out;
 			}
 			wreq->direct_bv = (struct bio_vec *)wreq->iter.bvec;
 			wreq->direct_bv_count = n;
 			wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter);
-			wreq->len = iov_iter_count(&wreq->iter);
 		} else {
 			wreq->iter = *iter;
 		}
 
 		wreq->io_iter = wreq->iter;
 	}
 
+	__set_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags);
+
 	/* Copy the data into the bounce buffer and encrypt it. */
 	// TODO
 
@@ -87,10 +93,7 @@ static ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov
 	if (async)
 		wreq->iocb = iocb;
 	wreq->cleanup = netfs_cleanup_dio_write;
-	ret = netfs_begin_write(wreq, is_sync_kiocb(iocb),
-				iocb->ki_flags & IOCB_DIRECT ?
-				netfs_write_trace_dio_write :
-				netfs_write_trace_unbuffered_write);
+	ret = netfs_unbuffered_write(wreq, is_sync_kiocb(iocb), iov_iter_count(&wreq->io_iter));
 	if (ret < 0) {
 		_debug("begin = %zd", ret);
 		goto out;
@@ -100,9 +103,8 @@ static ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov
 		trace_netfs_rreq(wreq, netfs_rreq_trace_wait_ip);
 		wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS,
 			    TASK_UNINTERRUPTIBLE);
-
+		smp_rmb(); /* Read error/transferred after RIP flag */
 		ret = wreq->error;
-		_debug("waited = %zd", ret);
 		if (ret == 0) {
 			ret = wreq->transferred;
 			iocb->ki_pos += ret;

fs/netfs/internal.h

@@ -92,15 +92,6 @@ static inline void netfs_see_request(struct netfs_io_request *rreq,
 	trace_netfs_rreq_ref(rreq->debug_id, refcount_read(&rreq->ref), what);
 }
 
-/*
- * output.c
- */
-int netfs_begin_write(struct netfs_io_request *wreq, bool may_wait,
-		      enum netfs_write_trace what);
-struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len);
-int netfs_advance_writethrough(struct netfs_io_request *wreq, size_t copied, bool to_page_end);
-int netfs_end_writethrough(struct netfs_io_request *wreq, struct kiocb *iocb);
-
 /*
  * stats.c
  */
@@ -172,12 +163,12 @@ void netfs_reissue_write(struct netfs_io_stream *stream,
 int netfs_advance_write(struct netfs_io_request *wreq,
 			struct netfs_io_stream *stream,
 			loff_t start, size_t len, bool to_eof);
-struct netfs_io_request *new_netfs_begin_writethrough(struct kiocb *iocb, size_t len);
-int new_netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
-				   struct folio *folio, size_t copied, bool to_page_end,
-				   struct folio **writethrough_cache);
-int new_netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
-			       struct folio *writethrough_cache);
+struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len);
+int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
+			       struct folio *folio, size_t copied, bool to_page_end,
+			       struct folio **writethrough_cache);
+int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
+			   struct folio *writethrough_cache);
 int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t len);
 
 /*

fs/netfs/write_collect.c

@@ -709,7 +709,7 @@ void netfs_wake_write_collector(struct netfs_io_request *wreq, bool was_async)
 }
 
 /**
- * new_netfs_write_subrequest_terminated - Note the termination of a write operation.
+ * netfs_write_subrequest_terminated - Note the termination of a write operation.
  * @_op: The I/O request that has terminated.
  * @transferred_or_error: The amount of data transferred or an error code.
  * @was_async: The termination was asynchronous
@@ -731,8 +731,8 @@ void netfs_wake_write_collector(struct netfs_io_request *wreq, bool was_async)
  * Note that %_op is a void* so that the function can be passed to
  * kiocb::term_func without the need for a casting wrapper.
  */
-void new_netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
-					   bool was_async)
+void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
+				       bool was_async)
 {
 	struct netfs_io_subrequest *subreq = _op;
 	struct netfs_io_request *wreq = subreq->rreq;
@@ -800,4 +800,4 @@ void new_netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_err
 
 	netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);
 }
-EXPORT_SYMBOL(new_netfs_write_subrequest_terminated);
+EXPORT_SYMBOL(netfs_write_subrequest_terminated);

fs/netfs/write_issue.c

@@ -494,8 +494,8 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
 /*
  * Write some of the pending data back to the server
  */
-int new_netfs_writepages(struct address_space *mapping,
-			 struct writeback_control *wbc)
+int netfs_writepages(struct address_space *mapping,
+		     struct writeback_control *wbc)
 {
 	struct netfs_inode *ictx = netfs_inode(mapping->host);
 	struct netfs_io_request *wreq = NULL;
@@ -556,12 +556,12 @@ int new_netfs_writepages(struct address_space *mapping,
 	_leave(" = %d", error);
 	return error;
 }
-EXPORT_SYMBOL(new_netfs_writepages);
+EXPORT_SYMBOL(netfs_writepages);
 
 /*
  * Begin a write operation for writing through the pagecache.
  */
-struct netfs_io_request *new_netfs_begin_writethrough(struct kiocb *iocb, size_t len)
+struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len)
 {
 	struct netfs_io_request *wreq = NULL;
 	struct netfs_inode *ictx = netfs_inode(file_inode(iocb->ki_filp));
@@ -586,9 +586,9 @@ struct netfs_io_request *new_netfs_begin_writethrough(struct kiocb *iocb, size_t
  * to the request.  If we've added more than wsize then we need to create a new
  * subrequest.
  */
-int new_netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
-				   struct folio *folio, size_t copied, bool to_page_end,
-				   struct folio **writethrough_cache)
+int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
+			       struct folio *folio, size_t copied, bool to_page_end,
+			       struct folio **writethrough_cache)
 {
 	_enter("R=%x ic=%zu ws=%u cp=%zu tp=%u",
 	       wreq->debug_id, wreq->iter.count, wreq->wsize, copied, to_page_end);
@@ -618,8 +618,8 @@ int new_netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeba
 /*
  * End a write operation used when writing through the pagecache.
  */
-int new_netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
-			       struct folio *writethrough_cache)
+int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
+			   struct folio *writethrough_cache)
 {
 	struct netfs_inode *ictx = netfs_inode(wreq->inode);
 	int ret;