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Message-ID: <87d451ff8cd030a380b522b4dfc56ca42c9de444.camel@kernel.org>
Date: Mon, 15 Apr 2024 08:20:42 -0400
From: Jeff Layton <jlayton@...nel.org>
To: David Howells <dhowells@...hat.com>, Christian Brauner
	 <christian@...uner.io>, Gao Xiang <hsiangkao@...ux.alibaba.com>, Dominique
	Martinet <asmadeus@...ewreck.org>
Cc: Matthew Wilcox <willy@...radead.org>, Steve French <smfrench@...il.com>,
  Marc Dionne <marc.dionne@...istor.com>, Paulo Alcantara
 <pc@...guebit.com>, Shyam Prasad N <sprasad@...rosoft.com>, Tom Talpey
 <tom@...pey.com>, Eric Van Hensbergen <ericvh@...nel.org>, Ilya Dryomov
 <idryomov@...il.com>, netfs@...ts.linux.dev,  linux-cachefs@...hat.com,
 linux-afs@...ts.infradead.org,  linux-cifs@...r.kernel.org,
 linux-nfs@...r.kernel.org,  ceph-devel@...r.kernel.org,
 v9fs@...ts.linux.dev, linux-erofs@...ts.ozlabs.org, 
 linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Latchesar Ionkov <lucho@...kov.net>,
 Christian Schoenebeck <linux_oss@...debyte.com>
Subject: Re: [PATCH 24/26] netfs: Remove the old writeback code

On Thu, 2024-03-28 at 16:34 +0000, David Howells wrote:
> Remove the old writeback code.
> 
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: Jeff Layton <jlayton@...nel.org>
> cc: Eric Van Hensbergen <ericvh@...nel.org>
> cc: Latchesar Ionkov <lucho@...kov.net>
> cc: Dominique Martinet <asmadeus@...ewreck.org>
> cc: Christian Schoenebeck <linux_oss@...debyte.com>
> cc: Marc Dionne <marc.dionne@...istor.com>
> cc: v9fs@...ts.linux.dev
> cc: linux-afs@...ts.infradead.org
> cc: netfs@...ts.linux.dev
> cc: linux-fsdevel@...r.kernel.org
> ---
>  fs/9p/vfs_addr.c          |  34 ---
>  fs/afs/write.c            |  40 ---
>  fs/netfs/buffered_write.c | 629 --------------------------------------
>  fs/netfs/direct_write.c   |   2 +-
>  fs/netfs/output.c         | 477 -----------------------------
>  5 files changed, 1 insertion(+), 1181 deletions(-)
>  delete mode 100644 fs/netfs/output.c
> 
> diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
> index 4845e655bc39..a97ceb105cd8 100644
> --- a/fs/9p/vfs_addr.c
> +++ b/fs/9p/vfs_addr.c
> @@ -60,40 +60,6 @@ static void v9fs_issue_write(struct netfs_io_subrequest *subreq)
>  	netfs_write_subrequest_terminated(subreq, len ?: err, false);
>  }
>  
> -#if 0 // TODO: Remove

#23 and #24 should probably be merged. I don't see any reason to do the
two-step of ifdef'ing out the code and then removing it. Just go for it
at this point in the series.

> -static void v9fs_upload_to_server(struct netfs_io_subrequest *subreq)
> -{
> -	struct p9_fid *fid = subreq->rreq->netfs_priv;
> -	int err, len;
> -
> -	trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
> -	len = p9_client_write(fid, subreq->start, &subreq->io_iter, &err);
> -	netfs_write_subrequest_terminated(subreq, len ?: err, false);
> -}
> -
> -static void v9fs_upload_to_server_worker(struct work_struct *work)
> -{
> -	struct netfs_io_subrequest *subreq =
> -		container_of(work, struct netfs_io_subrequest, work);
> -
> -	v9fs_upload_to_server(subreq);
> -}
> -
> -/*
> - * Set up write requests for a writeback slice.  We need to add a write request
> - * for each write we want to make.
> - */
> -static void v9fs_create_write_requests(struct netfs_io_request *wreq, loff_t start, size_t len)
> -{
> -	struct netfs_io_subrequest *subreq;
> -
> -	subreq = netfs_create_write_request(wreq, NETFS_UPLOAD_TO_SERVER,
> -					    start, len, v9fs_upload_to_server_worker);
> -	if (subreq)
> -		netfs_queue_write_request(subreq);
> -}
> -#endif
> -
>  /**
>   * v9fs_issue_read - Issue a read from 9P
>   * @subreq: The read to make
> diff --git a/fs/afs/write.c b/fs/afs/write.c
> index 0ead204c84cb..6ef7d4cbc008 100644
> --- a/fs/afs/write.c
> +++ b/fs/afs/write.c
> @@ -156,46 +156,6 @@ 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);
> -	ssize_t ret;
> -
> -	_enter("%x[%x],%zx",
> -	       subreq->rreq->debug_id, subreq->debug_index, subreq->io_iter.count);
> -
> -	trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
> -	ret = afs_store_data(vnode, &subreq->io_iter, subreq->start);
> -	netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len,
> -					  false);
> -}
> -
> -static void afs_upload_to_server_worker(struct work_struct *work)
> -{
> -	struct netfs_io_subrequest *subreq =
> -		container_of(work, struct netfs_io_subrequest, work);
> -
> -	afs_upload_to_server(subreq);
> -}
> -
> -/*
> - * Set up write requests for a writeback slice.  We need to add a write request
> - * for each write we want to make.
> - */
> -void afs_create_write_requests(struct netfs_io_request *wreq, loff_t start, size_t len)
> -{
> -	struct netfs_io_subrequest *subreq;
> -
> -	_enter("%x,%llx-%llx", wreq->debug_id, start, start + len);
> -
> -	subreq = netfs_create_write_request(wreq, NETFS_UPLOAD_TO_SERVER,
> -					    start, len, afs_upload_to_server_worker);
> -	if (subreq)
> -		netfs_queue_write_request(subreq);
> -}
> -#endif
> -
>  /*
>   * Writeback calls this when it finds a folio that needs uploading.  This isn't
>   * called if writeback only has copy-to-cache to deal with.
> diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
> index 945e646cd2db..2da9905abec9 100644
> --- a/fs/netfs/buffered_write.c
> +++ b/fs/netfs/buffered_write.c
> @@ -575,632 +575,3 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr
>  	return ret;
>  }
>  EXPORT_SYMBOL(netfs_page_mkwrite);
> -
> -#if 0 // TODO: Remove
> -/*
> - * Kill all the pages in the given range
> - */
> -static void netfs_kill_pages(struct address_space *mapping,
> -			     loff_t start, loff_t len)
> -{
> -	struct folio *folio;
> -	pgoff_t index = start / PAGE_SIZE;
> -	pgoff_t last = (start + len - 1) / PAGE_SIZE, next;
> -
> -	_enter("%llx-%llx", start, start + len - 1);
> -
> -	do {
> -		_debug("kill %lx (to %lx)", index, last);
> -
> -		folio = filemap_get_folio(mapping, index);
> -		if (IS_ERR(folio)) {
> -			next = index + 1;
> -			continue;
> -		}
> -
> -		next = folio_next_index(folio);
> -
> -		trace_netfs_folio(folio, netfs_folio_trace_kill);
> -		folio_clear_uptodate(folio);
> -		folio_end_writeback(folio);
> -		folio_lock(folio);
> -		generic_error_remove_folio(mapping, folio);
> -		folio_unlock(folio);
> -		folio_put(folio);
> -
> -	} while (index = next, index <= last);
> -
> -	_leave("");
> -}
> -
> -/*
> - * Redirty all the pages in a given range.
> - */
> -static void netfs_redirty_pages(struct address_space *mapping,
> -				loff_t start, loff_t len)
> -{
> -	struct folio *folio;
> -	pgoff_t index = start / PAGE_SIZE;
> -	pgoff_t last = (start + len - 1) / PAGE_SIZE, next;
> -
> -	_enter("%llx-%llx", start, start + len - 1);
> -
> -	do {
> -		_debug("redirty %llx @%llx", len, start);
> -
> -		folio = filemap_get_folio(mapping, index);
> -		if (IS_ERR(folio)) {
> -			next = index + 1;
> -			continue;
> -		}
> -
> -		next = folio_next_index(folio);
> -		trace_netfs_folio(folio, netfs_folio_trace_redirty);
> -		filemap_dirty_folio(mapping, folio);
> -		folio_end_writeback(folio);
> -		folio_put(folio);
> -	} while (index = next, index <= last);
> -
> -	balance_dirty_pages_ratelimited(mapping);
> -
> -	_leave("");
> -}
> -
> -/*
> - * Completion of write to server
> - */
> -static void netfs_pages_written_back(struct netfs_io_request *wreq)
> -{
> -	struct address_space *mapping = wreq->mapping;
> -	struct netfs_folio *finfo;
> -	struct netfs_group *group = NULL;
> -	struct folio *folio;
> -	pgoff_t last;
> -	int gcount = 0;
> -
> -	XA_STATE(xas, &mapping->i_pages, wreq->start / PAGE_SIZE);
> -
> -	_enter("%llx-%llx", wreq->start, wreq->start + wreq->len);
> -
> -	rcu_read_lock();
> -
> -	last = (wreq->start + wreq->len - 1) / PAGE_SIZE;
> -	xas_for_each(&xas, folio, last) {
> -		WARN(!folio_test_writeback(folio),
> -		     "bad %llx @%llx page %lx %lx\n",
> -		     wreq->len, wreq->start, folio->index, last);
> -
> -		if ((finfo = netfs_folio_info(folio))) {
> -			/* Streaming writes cannot be redirtied whilst under
> -			 * writeback, so discard the streaming record.
> -			 */
> -			folio_detach_private(folio);
> -			group = finfo->netfs_group;
> -			gcount++;
> -			trace_netfs_folio(folio, netfs_folio_trace_clear_s);
> -			kfree(finfo);
> -		} else if ((group = netfs_folio_group(folio))) {
> -			/* Need to detach the group pointer if the page didn't
> -			 * get redirtied.  If it has been redirtied, then it
> -			 * must be within the same group.
> -			 */
> -			if (folio_test_dirty(folio)) {
> -				trace_netfs_folio(folio, netfs_folio_trace_redirtied);
> -				goto end_wb;
> -			}
> -			if (folio_trylock(folio)) {
> -				if (!folio_test_dirty(folio)) {
> -					folio_detach_private(folio);
> -					gcount++;
> -					if (group == NETFS_FOLIO_COPY_TO_CACHE)
> -						trace_netfs_folio(folio,
> -								  netfs_folio_trace_end_copy);
> -					else
> -						trace_netfs_folio(folio, netfs_folio_trace_clear_g);
> -				} else {
> -					trace_netfs_folio(folio, netfs_folio_trace_redirtied);
> -				}
> -				folio_unlock(folio);
> -				goto end_wb;
> -			}
> -
> -			xas_pause(&xas);
> -			rcu_read_unlock();
> -			folio_lock(folio);
> -			if (!folio_test_dirty(folio)) {
> -				folio_detach_private(folio);
> -				gcount++;
> -				trace_netfs_folio(folio, netfs_folio_trace_clear_g);
> -			} else {
> -				trace_netfs_folio(folio, netfs_folio_trace_redirtied);
> -			}
> -			folio_unlock(folio);
> -			rcu_read_lock();
> -		} else {
> -			trace_netfs_folio(folio, netfs_folio_trace_clear);
> -		}
> -	end_wb:
> -		xas_advance(&xas, folio_next_index(folio) - 1);
> -		folio_end_writeback(folio);
> -	}
> -
> -	rcu_read_unlock();
> -	netfs_put_group_many(group, gcount);
> -	_leave("");
> -}
> -
> -/*
> - * Deal with the disposition of the folios that are under writeback to close
> - * out the operation.
> - */
> -static void netfs_cleanup_buffered_write(struct netfs_io_request *wreq)
> -{
> -	struct address_space *mapping = wreq->mapping;
> -
> -	_enter("");
> -
> -	switch (wreq->error) {
> -	case 0:
> -		netfs_pages_written_back(wreq);
> -		break;
> -
> -	default:
> -		pr_notice("R=%08x Unexpected error %d\n", wreq->debug_id, wreq->error);
> -		fallthrough;
> -	case -EACCES:
> -	case -EPERM:
> -	case -ENOKEY:
> -	case -EKEYEXPIRED:
> -	case -EKEYREJECTED:
> -	case -EKEYREVOKED:
> -	case -ENETRESET:
> -	case -EDQUOT:
> -	case -ENOSPC:
> -		netfs_redirty_pages(mapping, wreq->start, wreq->len);
> -		break;
> -
> -	case -EROFS:
> -	case -EIO:
> -	case -EREMOTEIO:
> -	case -EFBIG:
> -	case -ENOENT:
> -	case -ENOMEDIUM:
> -	case -ENXIO:
> -		netfs_kill_pages(mapping, wreq->start, wreq->len);
> -		break;
> -	}
> -
> -	if (wreq->error)
> -		mapping_set_error(mapping, wreq->error);
> -	if (wreq->netfs_ops->done)
> -		wreq->netfs_ops->done(wreq);
> -}
> -
> -/*
> - * Extend the region to be written back to include subsequent contiguously
> - * dirty pages if possible, but don't sleep while doing so.
> - *
> - * If this page holds new content, then we can include filler zeros in the
> - * writeback.
> - */
> -static void netfs_extend_writeback(struct address_space *mapping,
> -				   struct netfs_group *group,
> -				   struct xa_state *xas,
> -				   long *_count,
> -				   loff_t start,
> -				   loff_t max_len,
> -				   size_t *_len,
> -				   size_t *_top)
> -{
> -	struct netfs_folio *finfo;
> -	struct folio_batch fbatch;
> -	struct folio *folio;
> -	unsigned int i;
> -	pgoff_t index = (start + *_len) / PAGE_SIZE;
> -	size_t len;
> -	void *priv;
> -	bool stop = true;
> -
> -	folio_batch_init(&fbatch);
> -
> -	do {
> -		/* Firstly, we gather up a batch of contiguous dirty pages
> -		 * under the RCU read lock - but we can't clear the dirty flags
> -		 * there if any of those pages are mapped.
> -		 */
> -		rcu_read_lock();
> -
> -		xas_for_each(xas, folio, ULONG_MAX) {
> -			stop = true;
> -			if (xas_retry(xas, folio))
> -				continue;
> -			if (xa_is_value(folio))
> -				break;
> -			if (folio->index != index) {
> -				xas_reset(xas);
> -				break;
> -			}
> -
> -			if (!folio_try_get_rcu(folio)) {
> -				xas_reset(xas);
> -				continue;
> -			}
> -
> -			/* Has the folio moved or been split? */
> -			if (unlikely(folio != xas_reload(xas))) {
> -				folio_put(folio);
> -				xas_reset(xas);
> -				break;
> -			}
> -
> -			if (!folio_trylock(folio)) {
> -				folio_put(folio);
> -				xas_reset(xas);
> -				break;
> -			}
> -			if (!folio_test_dirty(folio) ||
> -			    folio_test_writeback(folio)) {
> -				folio_unlock(folio);
> -				folio_put(folio);
> -				xas_reset(xas);
> -				break;
> -			}
> -
> -			stop = false;
> -			len = folio_size(folio);
> -			priv = folio_get_private(folio);
> -			if ((const struct netfs_group *)priv != group) {
> -				stop = true;
> -				finfo = netfs_folio_info(folio);
> -				if (!finfo ||
> -				    finfo->netfs_group != group ||
> -				    finfo->dirty_offset > 0) {
> -					folio_unlock(folio);
> -					folio_put(folio);
> -					xas_reset(xas);
> -					break;
> -				}
> -				len = finfo->dirty_len;
> -			}
> -
> -			*_top += folio_size(folio);
> -			index += folio_nr_pages(folio);
> -			*_count -= folio_nr_pages(folio);
> -			*_len += len;
> -			if (*_len >= max_len || *_count <= 0)
> -				stop = true;
> -
> -			if (!folio_batch_add(&fbatch, folio))
> -				break;
> -			if (stop)
> -				break;
> -		}
> -
> -		xas_pause(xas);
> -		rcu_read_unlock();
> -
> -		/* Now, if we obtained any folios, we can shift them to being
> -		 * writable and mark them for caching.
> -		 */
> -		if (!folio_batch_count(&fbatch))
> -			break;
> -
> -		for (i = 0; i < folio_batch_count(&fbatch); i++) {
> -			folio = fbatch.folios[i];
> -			if (group == NETFS_FOLIO_COPY_TO_CACHE)
> -				trace_netfs_folio(folio, netfs_folio_trace_copy_plus);
> -			else
> -				trace_netfs_folio(folio, netfs_folio_trace_store_plus);
> -
> -			if (!folio_clear_dirty_for_io(folio))
> -				BUG();
> -			folio_start_writeback(folio);
> -			folio_unlock(folio);
> -		}
> -
> -		folio_batch_release(&fbatch);
> -		cond_resched();
> -	} while (!stop);
> -}
> -
> -/*
> - * Synchronously write back the locked page and any subsequent non-locked dirty
> - * pages.
> - */
> -static ssize_t netfs_write_back_from_locked_folio(struct address_space *mapping,
> -						  struct writeback_control *wbc,
> -						  struct netfs_group *group,
> -						  struct xa_state *xas,
> -						  struct folio *folio,
> -						  unsigned long long start,
> -						  unsigned long long end)
> -{
> -	struct netfs_io_request *wreq;
> -	struct netfs_folio *finfo;
> -	struct netfs_inode *ctx = netfs_inode(mapping->host);
> -	unsigned long long i_size = i_size_read(&ctx->inode);
> -	size_t len, max_len;
> -	long count = wbc->nr_to_write;
> -	int ret;
> -
> -	_enter(",%lx,%llx-%llx", folio->index, start, end);
> -
> -	wreq = netfs_alloc_request(mapping, NULL, start, folio_size(folio),
> -				   group == NETFS_FOLIO_COPY_TO_CACHE ?
> -				   NETFS_COPY_TO_CACHE : NETFS_WRITEBACK);
> -	if (IS_ERR(wreq)) {
> -		folio_unlock(folio);
> -		return PTR_ERR(wreq);
> -	}
> -
> -	if (!folio_clear_dirty_for_io(folio))
> -		BUG();
> -	folio_start_writeback(folio);
> -
> -	count -= folio_nr_pages(folio);
> -
> -	/* Find all consecutive lockable dirty pages that have contiguous
> -	 * written regions, stopping when we find a page that is not
> -	 * immediately lockable, is not dirty or is missing, or we reach the
> -	 * end of the range.
> -	 */
> -	if (group == NETFS_FOLIO_COPY_TO_CACHE)
> -		trace_netfs_folio(folio, netfs_folio_trace_copy);
> -	else
> -		trace_netfs_folio(folio, netfs_folio_trace_store);
> -
> -	len = wreq->len;
> -	finfo = netfs_folio_info(folio);
> -	if (finfo) {
> -		start += finfo->dirty_offset;
> -		if (finfo->dirty_offset + finfo->dirty_len != len) {
> -			len = finfo->dirty_len;
> -			goto cant_expand;
> -		}
> -		len = finfo->dirty_len;
> -	}
> -
> -	if (start < i_size) {
> -		/* Trim the write to the EOF; the extra data is ignored.  Also
> -		 * put an upper limit on the size of a single storedata op.
> -		 */
> -		max_len = 65536 * 4096;
> -		max_len = min_t(unsigned long long, max_len, end - start + 1);
> -		max_len = min_t(unsigned long long, max_len, i_size - start);
> -
> -		if (len < max_len)
> -			netfs_extend_writeback(mapping, group, xas, &count, start,
> -					       max_len, &len, &wreq->upper_len);
> -	}
> -
> -cant_expand:
> -	len = min_t(unsigned long long, len, i_size - start);
> -
> -	/* We now have a contiguous set of dirty pages, each with writeback
> -	 * set; the first page is still locked at this point, but all the rest
> -	 * have been unlocked.
> -	 */
> -	folio_unlock(folio);
> -	wreq->start = start;
> -	wreq->len = len;
> -
> -	if (start < i_size) {
> -		_debug("write back %zx @%llx [%llx]", len, start, i_size);
> -
> -		/* Speculatively write to the cache.  We have to fix this up
> -		 * later if the store fails.
> -		 */
> -		wreq->cleanup = netfs_cleanup_buffered_write;
> -
> -		iov_iter_xarray(&wreq->iter, ITER_SOURCE, &mapping->i_pages, start,
> -				wreq->upper_len);
> -		if (group != NETFS_FOLIO_COPY_TO_CACHE) {
> -			__set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags);
> -			ret = netfs_begin_write(wreq, true, netfs_write_trace_writeback);
> -		} else {
> -			ret = netfs_begin_write(wreq, true, netfs_write_trace_copy_to_cache);
> -		}
> -		if (ret == 0 || ret == -EIOCBQUEUED)
> -			wbc->nr_to_write -= len / PAGE_SIZE;
> -	} else {
> -		_debug("write discard %zx @%llx [%llx]", len, start, i_size);
> -
> -		/* The dirty region was entirely beyond the EOF. */
> -		netfs_pages_written_back(wreq);
> -		ret = 0;
> -	}
> -
> -	netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
> -	_leave(" = 1");
> -	return 1;
> -}
> -
> -/*
> - * Write a region of pages back to the server
> - */
> -static ssize_t netfs_writepages_begin(struct address_space *mapping,
> -				      struct writeback_control *wbc,
> -				      struct netfs_group *group,
> -				      struct xa_state *xas,
> -				      unsigned long long *_start,
> -				      unsigned long long end)
> -{
> -	const struct netfs_folio *finfo;
> -	struct folio *folio;
> -	unsigned long long start = *_start;
> -	ssize_t ret;
> -	void *priv;
> -	int skips = 0;
> -
> -	_enter("%llx,%llx,", start, end);
> -
> -search_again:
> -	/* Find the first dirty page in the group. */
> -	rcu_read_lock();
> -
> -	for (;;) {
> -		folio = xas_find_marked(xas, end / PAGE_SIZE, PAGECACHE_TAG_DIRTY);
> -		if (xas_retry(xas, folio) || xa_is_value(folio))
> -			continue;
> -		if (!folio)
> -			break;
> -
> -		if (!folio_try_get_rcu(folio)) {
> -			xas_reset(xas);
> -			continue;
> -		}
> -
> -		if (unlikely(folio != xas_reload(xas))) {
> -			folio_put(folio);
> -			xas_reset(xas);
> -			continue;
> -		}
> -
> -		/* Skip any dirty folio that's not in the group of interest. */
> -		priv = folio_get_private(folio);
> -		if ((const struct netfs_group *)priv == NETFS_FOLIO_COPY_TO_CACHE) {
> -			group = NETFS_FOLIO_COPY_TO_CACHE;
> -		} else if ((const struct netfs_group *)priv != group) {
> -			finfo = __netfs_folio_info(priv);
> -			if (!finfo || finfo->netfs_group != group) {
> -				folio_put(folio);
> -				continue;
> -			}
> -		}
> -
> -		xas_pause(xas);
> -		break;
> -	}
> -	rcu_read_unlock();
> -	if (!folio)
> -		return 0;
> -
> -	start = folio_pos(folio); /* May regress with THPs */
> -
> -	_debug("wback %lx", folio->index);
> -
> -	/* At this point we hold neither the i_pages lock nor the page lock:
> -	 * the page may be truncated or invalidated (changing page->mapping to
> -	 * NULL), or even swizzled back from swapper_space to tmpfs file
> -	 * mapping
> -	 */
> -lock_again:
> -	if (wbc->sync_mode != WB_SYNC_NONE) {
> -		ret = folio_lock_killable(folio);
> -		if (ret < 0)
> -			return ret;
> -	} else {
> -		if (!folio_trylock(folio))
> -			goto search_again;
> -	}
> -
> -	if (folio->mapping != mapping ||
> -	    !folio_test_dirty(folio)) {
> -		start += folio_size(folio);
> -		folio_unlock(folio);
> -		goto search_again;
> -	}
> -
> -	if (folio_test_writeback(folio)) {
> -		folio_unlock(folio);
> -		if (wbc->sync_mode != WB_SYNC_NONE) {
> -			folio_wait_writeback(folio);
> -			goto lock_again;
> -		}
> -
> -		start += folio_size(folio);
> -		if (wbc->sync_mode == WB_SYNC_NONE) {
> -			if (skips >= 5 || need_resched()) {
> -				ret = 0;
> -				goto out;
> -			}
> -			skips++;
> -		}
> -		goto search_again;
> -	}
> -
> -	ret = netfs_write_back_from_locked_folio(mapping, wbc, group, xas,
> -						 folio, start, end);
> -out:
> -	if (ret > 0)
> -		*_start = start + ret;
> -	_leave(" = %zd [%llx]", ret, *_start);
> -	return ret;
> -}
> -
> -/*
> - * Write a region of pages back to the server
> - */
> -static int netfs_writepages_region(struct address_space *mapping,
> -				   struct writeback_control *wbc,
> -				   struct netfs_group *group,
> -				   unsigned long long *_start,
> -				   unsigned long long end)
> -{
> -	ssize_t ret;
> -
> -	XA_STATE(xas, &mapping->i_pages, *_start / PAGE_SIZE);
> -
> -	do {
> -		ret = netfs_writepages_begin(mapping, wbc, group, &xas,
> -					     _start, end);
> -		if (ret > 0 && wbc->nr_to_write > 0)
> -			cond_resched();
> -	} while (ret > 0 && wbc->nr_to_write > 0);
> -
> -	return ret > 0 ? 0 : ret;
> -}
> -
> -/*
> - * write some of the pending data back to the server
> - */
> -int netfs_writepages(struct address_space *mapping,
> -		     struct writeback_control *wbc)
> -{
> -	struct netfs_group *group = NULL;
> -	loff_t start, end;
> -	int ret;
> -
> -	_enter("");
> -
> -	/* We have to be careful as we can end up racing with setattr()
> -	 * truncating the pagecache since the caller doesn't take a lock here
> -	 * to prevent it.
> -	 */
> -
> -	if (wbc->range_cyclic && mapping->writeback_index) {
> -		start = mapping->writeback_index * PAGE_SIZE;
> -		ret = netfs_writepages_region(mapping, wbc, group,
> -					      &start, LLONG_MAX);
> -		if (ret < 0)
> -			goto out;
> -
> -		if (wbc->nr_to_write <= 0) {
> -			mapping->writeback_index = start / PAGE_SIZE;
> -			goto out;
> -		}
> -
> -		start = 0;
> -		end = mapping->writeback_index * PAGE_SIZE;
> -		mapping->writeback_index = 0;
> -		ret = netfs_writepages_region(mapping, wbc, group, &start, end);
> -		if (ret == 0)
> -			mapping->writeback_index = start / PAGE_SIZE;
> -	} else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
> -		start = 0;
> -		ret = netfs_writepages_region(mapping, wbc, group,
> -					      &start, LLONG_MAX);
> -		if (wbc->nr_to_write > 0 && ret == 0)
> -			mapping->writeback_index = start / PAGE_SIZE;
> -	} else {
> -		start = wbc->range_start;
> -		ret = netfs_writepages_region(mapping, wbc, group,
> -					      &start, wbc->range_end);
> -	}
> -
> -out:
> -	_leave(" = %d", ret);
> -	return ret;
> -}
> -EXPORT_SYMBOL(netfs_writepages);
> -#endif
> diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c
> index 330ba7cb3f10..e4a9cf7cd234 100644
> --- a/fs/netfs/direct_write.c
> +++ b/fs/netfs/direct_write.c
> @@ -37,7 +37,7 @@ static ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov
>  	size_t len = iov_iter_count(iter);
>  	bool async = !is_sync_kiocb(iocb);
>  
> -	_enter("");
> +	_enter("%lx", iov_iter_count(iter));
>  
>  	/* 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
> diff --git a/fs/netfs/output.c b/fs/netfs/output.c
> deleted file mode 100644
> index 85374322f10f..000000000000
> --- a/fs/netfs/output.c
> +++ /dev/null
> @@ -1,477 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-only
> -/* Network filesystem high-level write support.
> - *
> - * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
> - * Written by David Howells (dhowells@...hat.com)
> - */
> -
> -#include <linux/fs.h>
> -#include <linux/mm.h>
> -#include <linux/pagemap.h>
> -#include <linux/slab.h>
> -#include <linux/writeback.h>
> -#include <linux/pagevec.h>
> -#include "internal.h"
> -
> -/**
> - * netfs_create_write_request - Create a write operation.
> - * @wreq: The write request this is storing from.
> - * @dest: The destination type
> - * @start: Start of the region this write will modify
> - * @len: Length of the modification
> - * @worker: The worker function to handle the write(s)
> - *
> - * Allocate a write operation, set it up and add it to the list on a write
> - * request.
> - */
> -struct netfs_io_subrequest *netfs_create_write_request(struct netfs_io_request *wreq,
> -						       enum netfs_io_source dest,
> -						       loff_t start, size_t len,
> -						       work_func_t worker)
> -{
> -	struct netfs_io_subrequest *subreq;
> -
> -	subreq = netfs_alloc_subrequest(wreq);
> -	if (subreq) {
> -		INIT_WORK(&subreq->work, worker);
> -		subreq->source	= dest;
> -		subreq->start	= start;
> -		subreq->len	= len;
> -
> -		switch (subreq->source) {
> -		case NETFS_UPLOAD_TO_SERVER:
> -			netfs_stat(&netfs_n_wh_upload);
> -			break;
> -		case NETFS_WRITE_TO_CACHE:
> -			netfs_stat(&netfs_n_wh_write);
> -			break;
> -		default:
> -			BUG();
> -		}
> -
> -		subreq->io_iter = wreq->io_iter;
> -		iov_iter_advance(&subreq->io_iter, subreq->start - wreq->start);
> -		iov_iter_truncate(&subreq->io_iter, subreq->len);
> -
> -		trace_netfs_sreq_ref(wreq->debug_id, subreq->debug_index,
> -				     refcount_read(&subreq->ref),
> -				     netfs_sreq_trace_new);
> -		atomic_inc(&wreq->nr_outstanding);
> -		list_add_tail(&subreq->rreq_link, &wreq->subrequests);
> -		trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
> -	}
> -
> -	return subreq;
> -}
> -EXPORT_SYMBOL(netfs_create_write_request);
> -
> -/*
> - * Process a completed write request once all the component operations have
> - * been completed.
> - */
> -static void netfs_write_terminated(struct netfs_io_request *wreq, bool was_async)
> -{
> -	struct netfs_io_subrequest *subreq;
> -	struct netfs_inode *ctx = netfs_inode(wreq->inode);
> -	size_t transferred = 0;
> -
> -	_enter("R=%x[]", wreq->debug_id);
> -
> -	trace_netfs_rreq(wreq, netfs_rreq_trace_write_done);
> -
> -	list_for_each_entry(subreq, &wreq->subrequests, rreq_link) {
> -		if (subreq->error || subreq->transferred == 0)
> -			break;
> -		transferred += subreq->transferred;
> -		if (subreq->transferred < subreq->len)
> -			break;
> -	}
> -	wreq->transferred = transferred;
> -
> -	list_for_each_entry(subreq, &wreq->subrequests, rreq_link) {
> -		if (!subreq->error)
> -			continue;
> -		switch (subreq->source) {
> -		case NETFS_UPLOAD_TO_SERVER:
> -			/* Depending on the type of failure, this may prevent
> -			 * writeback completion unless we're in disconnected
> -			 * mode.
> -			 */
> -			if (!wreq->error)
> -				wreq->error = subreq->error;
> -			break;
> -
> -		case NETFS_WRITE_TO_CACHE:
> -			/* Failure doesn't prevent writeback completion unless
> -			 * we're in disconnected mode.
> -			 */
> -			if (subreq->error != -ENOBUFS)
> -				ctx->ops->invalidate_cache(wreq);
> -			break;
> -
> -		default:
> -			WARN_ON_ONCE(1);
> -			if (!wreq->error)
> -				wreq->error = -EIO;
> -			return;
> -		}
> -	}
> -
> -	wreq->cleanup(wreq);
> -
> -	if (wreq->origin == NETFS_DIO_WRITE &&
> -	    wreq->mapping->nrpages) {
> -		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");
> -	trace_netfs_rreq(wreq, netfs_rreq_trace_wake_ip);
> -	clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &wreq->flags);
> -	wake_up_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS);
> -
> -	if (wreq->iocb) {
> -		wreq->iocb->ki_pos += transferred;
> -		if (wreq->iocb->ki_complete)
> -			wreq->iocb->ki_complete(
> -				wreq->iocb, wreq->error ? wreq->error : transferred);
> -	}
> -
> -	netfs_clear_subrequests(wreq, was_async);
> -	netfs_put_request(wreq, was_async, netfs_rreq_trace_put_complete);
> -}
> -
> -/*
> - * Deal with the completion of writing the data to the cache.
> - */
> -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;
> -	unsigned int u;
> -
> -	_enter("%x[%x] %zd", wreq->debug_id, subreq->debug_index, transferred_or_error);
> -
> -	switch (subreq->source) {
> -	case NETFS_UPLOAD_TO_SERVER:
> -		netfs_stat(&netfs_n_wh_upload_done);
> -		break;
> -	case NETFS_WRITE_TO_CACHE:
> -		netfs_stat(&netfs_n_wh_write_done);
> -		break;
> -	case NETFS_INVALID_WRITE:
> -		break;
> -	default:
> -		BUG();
> -	}
> -
> -	if (IS_ERR_VALUE(transferred_or_error)) {
> -		subreq->error = transferred_or_error;
> -		trace_netfs_failure(wreq, subreq, transferred_or_error,
> -				    netfs_fail_write);
> -		goto failed;
> -	}
> -
> -	if (WARN(transferred_or_error > subreq->len - subreq->transferred,
> -		 "Subreq excess write: R%x[%x] %zd > %zu - %zu",
> -		 wreq->debug_id, subreq->debug_index,
> -		 transferred_or_error, subreq->len, subreq->transferred))
> -		transferred_or_error = subreq->len - subreq->transferred;
> -
> -	subreq->error = 0;
> -	subreq->transferred += transferred_or_error;
> -
> -	if (iov_iter_count(&subreq->io_iter) != subreq->len - subreq->transferred)
> -		pr_warn("R=%08x[%u] ITER POST-MISMATCH %zx != %zx-%zx %x\n",
> -			wreq->debug_id, subreq->debug_index,
> -			iov_iter_count(&subreq->io_iter), subreq->len,
> -			subreq->transferred, subreq->io_iter.iter_type);
> -
> -	if (subreq->transferred < subreq->len)
> -		goto incomplete;
> -
> -	__clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
> -out:
> -	trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
> -
> -	/* If we decrement nr_outstanding to 0, the ref belongs to us. */
> -	u = atomic_dec_return(&wreq->nr_outstanding);
> -	if (u == 0)
> -		netfs_write_terminated(wreq, was_async);
> -	else if (u == 1)
> -		wake_up_var(&wreq->nr_outstanding);
> -
> -	netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);
> -	return;
> -
> -incomplete:
> -	if (transferred_or_error == 0) {
> -		if (__test_and_set_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags)) {
> -			subreq->error = -ENODATA;
> -			goto failed;
> -		}
> -	} else {
> -		__clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
> -	}
> -
> -	__set_bit(NETFS_SREQ_SHORT_IO, &subreq->flags);
> -	set_bit(NETFS_RREQ_INCOMPLETE_IO, &wreq->flags);
> -	goto out;
> -
> -failed:
> -	switch (subreq->source) {
> -	case NETFS_WRITE_TO_CACHE:
> -		netfs_stat(&netfs_n_wh_write_failed);
> -		set_bit(NETFS_RREQ_INCOMPLETE_IO, &wreq->flags);
> -		break;
> -	case NETFS_UPLOAD_TO_SERVER:
> -		netfs_stat(&netfs_n_wh_upload_failed);
> -		set_bit(NETFS_RREQ_FAILED, &wreq->flags);
> -		wreq->error = subreq->error;
> -		break;
> -	default:
> -		break;
> -	}
> -	goto out;
> -}
> -EXPORT_SYMBOL(netfs_write_subrequest_terminated);
> -
> -static void netfs_write_to_cache_op(struct netfs_io_subrequest *subreq)
> -{
> -	struct netfs_io_request *wreq = subreq->rreq;
> -	struct netfs_cache_resources *cres = &wreq->cache_resources;
> -
> -	trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
> -
> -	cres->ops->write(cres, subreq->start, &subreq->io_iter,
> -			 netfs_write_subrequest_terminated, subreq);
> -}
> -
> -static void netfs_write_to_cache_op_worker(struct work_struct *work)
> -{
> -	struct netfs_io_subrequest *subreq =
> -		container_of(work, struct netfs_io_subrequest, work);
> -
> -	netfs_write_to_cache_op(subreq);
> -}
> -
> -/**
> - * netfs_queue_write_request - Queue a write request for attention
> - * @subreq: The write request to be queued
> - *
> - * Queue the specified write request for processing by a worker thread.  We
> - * pass the caller's ref on the request to the worker thread.
> - */
> -void netfs_queue_write_request(struct netfs_io_subrequest *subreq)
> -{
> -	if (!queue_work(system_unbound_wq, &subreq->work))
> -		netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_wip);
> -}
> -EXPORT_SYMBOL(netfs_queue_write_request);
> -
> -/*
> - * Set up a op for writing to the cache.
> - */
> -static void netfs_set_up_write_to_cache(struct netfs_io_request *wreq)
> -{
> -	struct netfs_cache_resources *cres = &wreq->cache_resources;
> -	struct netfs_io_subrequest *subreq;
> -	struct netfs_inode *ctx = netfs_inode(wreq->inode);
> -	struct fscache_cookie *cookie = netfs_i_cookie(ctx);
> -	loff_t start = wreq->start;
> -	size_t len = wreq->len;
> -	int ret;
> -
> -	if (!fscache_cookie_enabled(cookie)) {
> -		clear_bit(NETFS_RREQ_WRITE_TO_CACHE, &wreq->flags);
> -		return;
> -	}
> -
> -	_debug("write to cache");
> -	ret = fscache_begin_write_operation(cres, cookie);
> -	if (ret < 0)
> -		return;
> -
> -	ret = cres->ops->prepare_write(cres, &start, &len, wreq->upper_len,
> -				       i_size_read(wreq->inode), true);
> -	if (ret < 0)
> -		return;
> -
> -	subreq = netfs_create_write_request(wreq, NETFS_WRITE_TO_CACHE, start, len,
> -					    netfs_write_to_cache_op_worker);
> -	if (!subreq)
> -		return;
> -
> -	netfs_write_to_cache_op(subreq);
> -}
> -
> -/*
> - * Begin the process of writing out a chunk of data.
> - *
> - * We are given a write request that holds a series of dirty regions and
> - * (partially) covers a sequence of folios, all of which are present.  The
> - * pages must have been marked as writeback as appropriate.
> - *
> - * We need to perform the following steps:
> - *
> - * (1) If encrypting, create an output buffer and encrypt each block of the
> - *     data into it, otherwise the output buffer will point to the original
> - *     folios.
> - *
> - * (2) If the data is to be cached, set up a write op for the entire output
> - *     buffer to the cache, if the cache wants to accept it.
> - *
> - * (3) If the data is to be uploaded (ie. not merely cached):
> - *
> - *     (a) If the data is to be compressed, create a compression buffer and
> - *         compress the data into it.
> - *
> - *     (b) For each destination we want to upload to, set up write ops to write
> - *         to that destination.  We may need multiple writes if the data is not
> - *         contiguous or the span exceeds wsize for a server.
> - */
> -int netfs_begin_write(struct netfs_io_request *wreq, bool may_wait,
> -		      enum netfs_write_trace what)
> -{
> -	struct netfs_inode *ctx = netfs_inode(wreq->inode);
> -
> -	_enter("R=%x %llx-%llx f=%lx",
> -	       wreq->debug_id, wreq->start, wreq->start + wreq->len - 1,
> -	       wreq->flags);
> -
> -	trace_netfs_write(wreq, what);
> -	if (wreq->len == 0 || wreq->iter.count == 0) {
> -		pr_err("Zero-sized write [R=%x]\n", wreq->debug_id);
> -		return -EIO;
> -	}
> -
> -	if (wreq->origin == NETFS_DIO_WRITE)
> -		inode_dio_begin(wreq->inode);
> -
> -	wreq->io_iter = wreq->iter;
> -
> -	/* ->outstanding > 0 carries a ref */
> -	netfs_get_request(wreq, netfs_rreq_trace_get_for_outstanding);
> -	atomic_set(&wreq->nr_outstanding, 1);
> -
> -	/* Start the encryption/compression going.  We can do that in the
> -	 * background whilst we generate a list of write ops that we want to
> -	 * perform.
> -	 */
> -	// TODO: Encrypt or compress the region as appropriate
> -
> -	/* We need to write all of the region to the cache */
> -	if (test_bit(NETFS_RREQ_WRITE_TO_CACHE, &wreq->flags))
> -		netfs_set_up_write_to_cache(wreq);
> -
> -	/* However, we don't necessarily write all of the region to the server.
> -	 * Caching of reads is being managed this way also.
> -	 */
> -	if (test_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags))
> -		ctx->ops->create_write_requests(wreq, wreq->start, wreq->len);
> -
> -	if (atomic_dec_and_test(&wreq->nr_outstanding))
> -		netfs_write_terminated(wreq, false);
> -
> -	if (!may_wait)
> -		return -EIOCBQUEUED;
> -
> -	wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS,
> -		    TASK_UNINTERRUPTIBLE);
> -	return wreq->error;
> -}
> -
> -/*
> - * Begin a write operation for writing through the pagecache.
> - */
> -struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len)
> -{
> -	struct netfs_io_request *wreq;
> -	struct file *file = iocb->ki_filp;
> -
> -	wreq = netfs_alloc_request(file->f_mapping, file, iocb->ki_pos, len,
> -				   NETFS_WRITETHROUGH);
> -	if (IS_ERR(wreq))
> -		return wreq;
> -
> -	trace_netfs_write(wreq, netfs_write_trace_writethrough);
> -
> -	__set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags);
> -	iov_iter_xarray(&wreq->iter, ITER_SOURCE, &wreq->mapping->i_pages, wreq->start, 0);
> -	wreq->io_iter = wreq->iter;
> -
> -	/* ->outstanding > 0 carries a ref */
> -	netfs_get_request(wreq, netfs_rreq_trace_get_for_outstanding);
> -	atomic_set(&wreq->nr_outstanding, 1);
> -	return wreq;
> -}
> -
> -static void netfs_submit_writethrough(struct netfs_io_request *wreq, bool final)
> -{
> -	struct netfs_inode *ictx = netfs_inode(wreq->inode);
> -	unsigned long long start;
> -	size_t len;
> -
> -	if (!test_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags))
> -		return;
> -
> -	start = wreq->start + wreq->submitted;
> -	len = wreq->iter.count - wreq->submitted;
> -	if (!final) {
> -		len /= wreq->wsize; /* Round to number of maximum packets */
> -		len *= wreq->wsize;
> -	}
> -
> -	ictx->ops->create_write_requests(wreq, start, len);
> -	wreq->submitted += len;
> -}
> -
> -/*
> - * Advance the state of the write operation used when writing through the
> - * pagecache.  Data has been copied into the pagecache that we need to append
> - * to the request.  If we've added more than wsize then we need to create a new
> - * subrequest.
> - */
> -int netfs_advance_writethrough(struct netfs_io_request *wreq, size_t copied, bool to_page_end)
> -{
> -	_enter("ic=%zu sb=%llu ws=%u cp=%zu tp=%u",
> -	       wreq->iter.count, wreq->submitted, wreq->wsize, copied, to_page_end);
> -
> -	wreq->iter.count += copied;
> -	wreq->io_iter.count += copied;
> -	if (to_page_end && wreq->io_iter.count - wreq->submitted >= wreq->wsize)
> -		netfs_submit_writethrough(wreq, false);
> -
> -	return wreq->error;
> -}
> -
> -/*
> - * End a write operation used when writing through the pagecache.
> - */
> -int netfs_end_writethrough(struct netfs_io_request *wreq, struct kiocb *iocb)
> -{
> -	int ret = -EIOCBQUEUED;
> -
> -	_enter("ic=%zu sb=%llu ws=%u",
> -	       wreq->iter.count, wreq->submitted, wreq->wsize);
> -
> -	if (wreq->submitted < wreq->io_iter.count)
> -		netfs_submit_writethrough(wreq, true);
> -
> -	if (atomic_dec_and_test(&wreq->nr_outstanding))
> -		netfs_write_terminated(wreq, false);
> -
> -	if (is_sync_kiocb(iocb)) {
> -		wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS,
> -			    TASK_UNINTERRUPTIBLE);
> -		ret = wreq->error;
> -	}
> -
> -	netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
> -	return ret;
> -}
> 

-- 
Jeff Layton <jlayton@...nel.org>

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