--- zzzz-none-000/linux-3.10.107/fs/nfs/write.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/nfs/write.c	2021-02-04 17:41:59.000000000 +0000
@@ -31,6 +31,8 @@
 #include "fscache.h"
 #include "pnfs.h"
 
+#include "nfstrace.h"
+
 #define NFSDBG_FACILITY		NFSDBG_PAGECACHE
 
 #define MIN_POOL_WRITE		(32)
@@ -40,10 +42,16 @@
  * Local function declarations
  */
 static void nfs_redirty_request(struct nfs_page *req);
-static const struct rpc_call_ops nfs_write_common_ops;
 static const struct rpc_call_ops nfs_commit_ops;
 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
+static const struct nfs_rw_ops nfs_rw_write_ops;
+static void nfs_clear_request_commit(struct nfs_page *req);
+static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
+				      struct inode *inode);
+static struct nfs_page *
+nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
+						struct page *page);
 
 static struct kmem_cache *nfs_wdata_cachep;
 static mempool_t *nfs_wdata_mempool;
@@ -68,76 +76,19 @@
 }
 EXPORT_SYMBOL_GPL(nfs_commit_free);
 
-struct nfs_write_header *nfs_writehdr_alloc(void)
+static struct nfs_pgio_header *nfs_writehdr_alloc(void)
 {
-	struct nfs_write_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOIO);
-
-	if (p) {
-		struct nfs_pgio_header *hdr = &p->header;
+	struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOIO);
 
+	if (p)
 		memset(p, 0, sizeof(*p));
-		INIT_LIST_HEAD(&hdr->pages);
-		INIT_LIST_HEAD(&hdr->rpc_list);
-		spin_lock_init(&hdr->lock);
-		atomic_set(&hdr->refcnt, 0);
-		hdr->verf = &p->verf;
-	}
 	return p;
 }
-EXPORT_SYMBOL_GPL(nfs_writehdr_alloc);
-
-static struct nfs_write_data *nfs_writedata_alloc(struct nfs_pgio_header *hdr,
-						  unsigned int pagecount)
-{
-	struct nfs_write_data *data, *prealloc;
-
-	prealloc = &container_of(hdr, struct nfs_write_header, header)->rpc_data;
-	if (prealloc->header == NULL)
-		data = prealloc;
-	else
-		data = kzalloc(sizeof(*data), GFP_KERNEL);
-	if (!data)
-		goto out;
-
-	if (nfs_pgarray_set(&data->pages, pagecount)) {
-		data->header = hdr;
-		atomic_inc(&hdr->refcnt);
-	} else {
-		if (data != prealloc)
-			kfree(data);
-		data = NULL;
-	}
-out:
-	return data;
-}
-
-void nfs_writehdr_free(struct nfs_pgio_header *hdr)
-{
-	struct nfs_write_header *whdr = container_of(hdr, struct nfs_write_header, header);
-	mempool_free(whdr, nfs_wdata_mempool);
-}
-EXPORT_SYMBOL_GPL(nfs_writehdr_free);
 
-void nfs_writedata_release(struct nfs_write_data *wdata)
+static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 {
-	struct nfs_pgio_header *hdr = wdata->header;
-	struct nfs_write_header *write_header = container_of(hdr, struct nfs_write_header, header);
-
-	put_nfs_open_context(wdata->args.context);
-	if (wdata->pages.pagevec != wdata->pages.page_array)
-		kfree(wdata->pages.pagevec);
-	if (wdata == &write_header->rpc_data) {
-		wdata->header = NULL;
-		wdata = NULL;
-	}
-	if (atomic_dec_and_test(&hdr->refcnt))
-		hdr->completion_ops->completion(hdr);
-	/* Note: we only free the rpc_task after callbacks are done.
-	 * See the comment in rpc_free_task() for why
-	 */
-	kfree(wdata);
+	mempool_free(hdr, nfs_wdata_mempool);
 }
-EXPORT_SYMBOL_GPL(nfs_writedata_release);
 
 static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
 {
@@ -146,38 +97,44 @@
 	set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 }
 
+/*
+ * nfs_page_find_head_request_locked - find head request associated with @page
+ *
+ * must be called while holding the inode lock.
+ *
+ * returns matching head request with reference held, or NULL if not found.
+ */
 static struct nfs_page *
-nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page)
+nfs_page_find_head_request_locked(struct nfs_inode *nfsi, struct page *page)
 {
 	struct nfs_page *req = NULL;
 
 	if (PagePrivate(page))
 		req = (struct nfs_page *)page_private(page);
-	else if (unlikely(PageSwapCache(page))) {
-		struct nfs_page *freq, *t;
-
-		/* Linearly search the commit list for the correct req */
-		list_for_each_entry_safe(freq, t, &nfsi->commit_info.list, wb_list) {
-			if (freq->wb_page == page) {
-				req = freq;
-				break;
-			}
-		}
-	}
+	else if (unlikely(PageSwapCache(page)))
+		req = nfs_page_search_commits_for_head_request_locked(nfsi,
+			page);
 
-	if (req)
+	if (req) {
+		WARN_ON_ONCE(req->wb_head != req);
 		kref_get(&req->wb_kref);
+	}
 
 	return req;
 }
 
-static struct nfs_page *nfs_page_find_request(struct page *page)
+/*
+ * nfs_page_find_head_request - find head request associated with @page
+ *
+ * returns matching head request with reference held, or NULL if not found.
+ */
+static struct nfs_page *nfs_page_find_head_request(struct page *page)
 {
 	struct inode *inode = page_file_mapping(page)->host;
 	struct nfs_page *req = NULL;
 
 	spin_lock(&inode->i_lock);
-	req = nfs_page_find_request_locked(NFS_I(inode), page);
+	req = nfs_page_find_head_request_locked(NFS_I(inode), page);
 	spin_unlock(&inode->i_lock);
 	return req;
 }
@@ -209,27 +166,90 @@
 	nfs_zap_mapping(page_file_mapping(page)->host, page_file_mapping(page));
 }
 
+/*
+ * nfs_page_group_search_locked
+ * @head - head request of page group
+ * @page_offset - offset into page
+ *
+ * Search page group with head @head to find a request that contains the
+ * page offset @page_offset.
+ *
+ * Returns a pointer to the first matching nfs request, or NULL if no
+ * match is found.
+ *
+ * Must be called with the page group lock held
+ */
+static struct nfs_page *
+nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
+{
+	struct nfs_page *req;
+
+	WARN_ON_ONCE(head != head->wb_head);
+	WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_head->wb_flags));
+
+	req = head;
+	do {
+		if (page_offset >= req->wb_pgbase &&
+		    page_offset < (req->wb_pgbase + req->wb_bytes))
+			return req;
+
+		req = req->wb_this_page;
+	} while (req != head);
+
+	return NULL;
+}
+
+/*
+ * nfs_page_group_covers_page
+ * @head - head request of page group
+ *
+ * Return true if the page group with head @head covers the whole page,
+ * returns false otherwise
+ */
+static bool nfs_page_group_covers_page(struct nfs_page *req)
+{
+	struct nfs_page *tmp;
+	unsigned int pos = 0;
+	unsigned int len = nfs_page_length(req->wb_page);
+
+	nfs_page_group_lock(req, false);
+
+	do {
+		tmp = nfs_page_group_search_locked(req->wb_head, pos);
+		if (tmp) {
+			/* no way this should happen */
+			WARN_ON_ONCE(tmp->wb_pgbase != pos);
+			pos += tmp->wb_bytes - (pos - tmp->wb_pgbase);
+		}
+	} while (tmp && pos < len);
+
+	nfs_page_group_unlock(req);
+	WARN_ON_ONCE(pos > len);
+	return pos == len;
+}
+
 /* We can set the PG_uptodate flag if we see that a write request
  * covers the full page.
  */
-static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
+static void nfs_mark_uptodate(struct nfs_page *req)
 {
-	if (PageUptodate(page))
-		return;
-	if (base != 0)
+	if (PageUptodate(req->wb_page))
 		return;
-	if (count != nfs_page_length(page))
+	if (!nfs_page_group_covers_page(req))
 		return;
-	SetPageUptodate(page);
+	SetPageUptodate(req->wb_page);
 }
 
 static int wb_priority(struct writeback_control *wbc)
 {
+	int ret = 0;
 	if (wbc->for_reclaim)
 		return FLUSH_HIGHPRI | FLUSH_STABLE;
+	if (wbc->sync_mode == WB_SYNC_ALL)
+		ret = FLUSH_COND_STABLE;
 	if (wbc->for_kupdate || wbc->for_background)
-		return FLUSH_LOWPRI | FLUSH_COND_STABLE;
-	return FLUSH_COND_STABLE;
+		ret |= FLUSH_LOWPRI;
+	return ret;
 }
 
 /*
@@ -256,46 +276,273 @@
 	}
 }
 
-static void nfs_end_page_writeback(struct page *page)
+static void nfs_end_page_writeback(struct nfs_page *req)
 {
-	struct inode *inode = page_file_mapping(page)->host;
+	struct inode *inode = page_file_mapping(req->wb_page)->host;
 	struct nfs_server *nfss = NFS_SERVER(inode);
 
-	end_page_writeback(page);
+	if (!nfs_page_group_sync_on_bit(req, PG_WB_END))
+		return;
+
+	end_page_writeback(req->wb_page);
 	if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 		clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
 }
 
-static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblock)
+
+/* nfs_page_group_clear_bits
+ *   @req - an nfs request
+ * clears all page group related bits from @req
+ */
+static void
+nfs_page_group_clear_bits(struct nfs_page *req)
+{
+	clear_bit(PG_TEARDOWN, &req->wb_flags);
+	clear_bit(PG_UNLOCKPAGE, &req->wb_flags);
+	clear_bit(PG_UPTODATE, &req->wb_flags);
+	clear_bit(PG_WB_END, &req->wb_flags);
+	clear_bit(PG_REMOVE, &req->wb_flags);
+}
+
+
+/*
+ * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
+ *
+ * this is a helper function for nfs_lock_and_join_requests
+ *
+ * @inode - inode associated with request page group, must be holding inode lock
+ * @head  - head request of page group, must be holding head lock
+ * @req   - request that couldn't lock and needs to wait on the req bit lock
+ * @nonblock - if true, don't actually wait
+ *
+ * NOTE: this must be called holding page_group bit lock and inode spin lock
+ *       and BOTH will be released before returning.
+ *
+ * returns 0 on success, < 0 on error.
+ */
+static int
+nfs_unroll_locks_and_wait(struct inode *inode, struct nfs_page *head,
+			  struct nfs_page *req, bool nonblock)
+	__releases(&inode->i_lock)
+{
+	struct nfs_page *tmp;
+	int ret;
+
+	/* relinquish all the locks successfully grabbed this run */
+	for (tmp = head ; tmp != req; tmp = tmp->wb_this_page)
+		nfs_unlock_request(tmp);
+
+	WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
+
+	/* grab a ref on the request that will be waited on */
+	kref_get(&req->wb_kref);
+
+	nfs_page_group_unlock(head);
+	spin_unlock(&inode->i_lock);
+
+	/* release ref from nfs_page_find_head_request_locked */
+	nfs_release_request(head);
+
+	if (!nonblock)
+		ret = nfs_wait_on_request(req);
+	else
+		ret = -EAGAIN;
+	nfs_release_request(req);
+
+	return ret;
+}
+
+/*
+ * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
+ *
+ * @destroy_list - request list (using wb_this_page) terminated by @old_head
+ * @old_head - the old head of the list
+ *
+ * All subrequests must be locked and removed from all lists, so at this point
+ * they are only "active" in this function, and possibly in nfs_wait_on_request
+ * with a reference held by some other context.
+ */
+static void
+nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
+				 struct nfs_page *old_head)
+{
+	while (destroy_list) {
+		struct nfs_page *subreq = destroy_list;
+
+		destroy_list = (subreq->wb_this_page == old_head) ?
+				   NULL : subreq->wb_this_page;
+
+		WARN_ON_ONCE(old_head != subreq->wb_head);
+
+		/* make sure old group is not used */
+		subreq->wb_head = subreq;
+		subreq->wb_this_page = subreq;
+
+		/* subreq is now totally disconnected from page group or any
+		 * write / commit lists. last chance to wake any waiters */
+		nfs_unlock_request(subreq);
+
+		if (!test_bit(PG_TEARDOWN, &subreq->wb_flags)) {
+			/* release ref on old head request */
+			nfs_release_request(old_head);
+
+			nfs_page_group_clear_bits(subreq);
+
+			/* release the PG_INODE_REF reference */
+			if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags))
+				nfs_release_request(subreq);
+			else
+				WARN_ON_ONCE(1);
+		} else {
+			WARN_ON_ONCE(test_bit(PG_CLEAN, &subreq->wb_flags));
+			/* zombie requests have already released the last
+			 * reference and were waiting on the rest of the
+			 * group to complete. Since it's no longer part of a
+			 * group, simply free the request */
+			nfs_page_group_clear_bits(subreq);
+			nfs_free_request(subreq);
+		}
+	}
+}
+
+/*
+ * nfs_lock_and_join_requests - join all subreqs to the head req and return
+ *                              a locked reference, cancelling any pending
+ *                              operations for this page.
+ *
+ * @page - the page used to lookup the "page group" of nfs_page structures
+ * @nonblock - if true, don't block waiting for request locks
+ *
+ * This function joins all sub requests to the head request by first
+ * locking all requests in the group, cancelling any pending operations
+ * and finally updating the head request to cover the whole range covered by
+ * the (former) group.  All subrequests are removed from any write or commit
+ * lists, unlinked from the group and destroyed.
+ *
+ * Returns a locked, referenced pointer to the head request - which after
+ * this call is guaranteed to be the only request associated with the page.
+ * Returns NULL if no requests are found for @page, or a ERR_PTR if an
+ * error was encountered.
+ */
+static struct nfs_page *
+nfs_lock_and_join_requests(struct page *page, bool nonblock)
 {
 	struct inode *inode = page_file_mapping(page)->host;
-	struct nfs_page *req;
+	struct nfs_page *head, *subreq;
+	struct nfs_page *destroy_list = NULL;
+	unsigned int total_bytes;
 	int ret;
 
+try_again:
+	total_bytes = 0;
+
+	WARN_ON_ONCE(destroy_list);
+
 	spin_lock(&inode->i_lock);
-	for (;;) {
-		req = nfs_page_find_request_locked(NFS_I(inode), page);
-		if (req == NULL)
-			break;
-		if (nfs_lock_request(req))
-			break;
-		/* Note: If we hold the page lock, as is the case in nfs_writepage,
-		 *	 then the call to nfs_lock_request() will always
-		 *	 succeed provided that someone hasn't already marked the
-		 *	 request as dirty (in which case we don't care).
-		 */
+
+	/*
+	 * A reference is taken only on the head request which acts as a
+	 * reference to the whole page group - the group will not be destroyed
+	 * until the head reference is released.
+	 */
+	head = nfs_page_find_head_request_locked(NFS_I(inode), page);
+
+	if (!head) {
 		spin_unlock(&inode->i_lock);
-		if (!nonblock)
-			ret = nfs_wait_on_request(req);
-		else
-			ret = -EAGAIN;
-		nfs_release_request(req);
-		if (ret != 0)
+		return NULL;
+	}
+
+	/* holding inode lock, so always make a non-blocking call to try the
+	 * page group lock */
+	ret = nfs_page_group_lock(head, true);
+	if (ret < 0) {
+		spin_unlock(&inode->i_lock);
+
+		if (!nonblock && ret == -EAGAIN) {
+			nfs_page_group_lock_wait(head);
+			nfs_release_request(head);
+			goto try_again;
+		}
+
+		nfs_release_request(head);
+		return ERR_PTR(ret);
+	}
+
+	/* lock each request in the page group */
+	subreq = head;
+	do {
+		/*
+		 * Subrequests are always contiguous, non overlapping
+		 * and in order - but may be repeated (mirrored writes).
+		 */
+		if (subreq->wb_offset == (head->wb_offset + total_bytes)) {
+			/* keep track of how many bytes this group covers */
+			total_bytes += subreq->wb_bytes;
+		} else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
+			    ((subreq->wb_offset + subreq->wb_bytes) >
+			     (head->wb_offset + total_bytes)))) {
+			nfs_page_group_unlock(head);
+			spin_unlock(&inode->i_lock);
+			return ERR_PTR(-EIO);
+		}
+
+		if (!nfs_lock_request(subreq)) {
+			/* releases page group bit lock and
+			 * inode spin lock and all references */
+			ret = nfs_unroll_locks_and_wait(inode, head,
+				subreq, nonblock);
+
+			if (ret == 0)
+				goto try_again;
+
 			return ERR_PTR(ret);
-		spin_lock(&inode->i_lock);
+		}
+
+		subreq = subreq->wb_this_page;
+	} while (subreq != head);
+
+	/* Now that all requests are locked, make sure they aren't on any list.
+	 * Commit list removal accounting is done after locks are dropped */
+	subreq = head;
+	do {
+		nfs_clear_request_commit(subreq);
+		subreq = subreq->wb_this_page;
+	} while (subreq != head);
+
+	/* unlink subrequests from head, destroy them later */
+	if (head->wb_this_page != head) {
+		/* destroy list will be terminated by head */
+		destroy_list = head->wb_this_page;
+		head->wb_this_page = head;
+
+		/* change head request to cover whole range that
+		 * the former page group covered */
+		head->wb_bytes = total_bytes;
 	}
+
+	/*
+	 * prepare head request to be added to new pgio descriptor
+	 */
+	nfs_page_group_clear_bits(head);
+
+	/*
+	 * some part of the group was still on the inode list - otherwise
+	 * the group wouldn't be involved in async write.
+	 * grab a reference for the head request, iff it needs one.
+	 */
+	if (!test_and_set_bit(PG_INODE_REF, &head->wb_flags))
+		kref_get(&head->wb_kref);
+
+	nfs_page_group_unlock(head);
+
+	/* drop lock to clean uprequests on destroy list */
 	spin_unlock(&inode->i_lock);
-	return req;
+
+	nfs_destroy_unlinked_subrequests(destroy_list, head);
+
+	/* still holds ref on head from nfs_page_find_head_request_locked
+	 * and still has lock on head from lock loop */
+	return head;
 }
 
 /*
@@ -308,7 +555,7 @@
 	struct nfs_page *req;
 	int ret = 0;
 
-	req = nfs_find_and_lock_request(page, nonblock);
+	req = nfs_lock_and_join_requests(page, nonblock);
 	if (!req)
 		goto out;
 	ret = PTR_ERR(req);
@@ -322,19 +569,17 @@
 	if (!nfs_pageio_add_request(pgio, req)) {
 		nfs_redirty_request(req);
 		ret = pgio->pg_error;
-	}
+	} else
+		nfs_add_stats(page_file_mapping(page)->host,
+				NFSIOS_WRITEPAGES, 1);
 out:
 	return ret;
 }
 
 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 {
-	struct inode *inode = page_file_mapping(page)->host;
 	int ret;
 
-	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
-	nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
-
 	nfs_pageio_cond_complete(pgio, page_file_index(page));
 	ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);
 	if (ret == -EAGAIN) {
@@ -350,12 +595,12 @@
 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 {
 	struct nfs_pageio_descriptor pgio;
+	struct inode *inode = page_file_mapping(page)->host;
 	int err;
 
-	NFS_PROTO(page_file_mapping(page)->host)->write_pageio_init(&pgio,
-							  page->mapping->host,
-							  wb_priority(wbc),
-							  &nfs_async_write_completion_ops);
+	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
+	nfs_pageio_init_write(&pgio, inode, wb_priority(wbc),
+				false, &nfs_async_write_completion_ops);
 	err = nfs_do_writepage(page, wbc, &pgio);
 	nfs_pageio_complete(&pgio);
 	if (err < 0)
@@ -391,19 +636,20 @@
 	int err;
 
 	/* Stop dirtying of new pages while we sync */
-	err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
+	err = wait_on_bit_lock_action(bitlock, NFS_INO_FLUSHING,
 			nfs_wait_bit_killable, TASK_KILLABLE);
 	if (err)
 		goto out_err;
 
 	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 
-	NFS_PROTO(inode)->write_pageio_init(&pgio, inode, wb_priority(wbc), &nfs_async_write_completion_ops);
+	nfs_pageio_init_write(&pgio, inode, wb_priority(wbc), false,
+				&nfs_async_write_completion_ops);
 	err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 	nfs_pageio_complete(&pgio);
 
 	clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
-	smp_mb__after_clear_bit();
+	smp_mb__after_atomic();
 	wake_up_bit(bitlock, NFS_INO_FLUSHING);
 
 	if (err < 0)
@@ -423,11 +669,14 @@
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
 
+	WARN_ON_ONCE(req->wb_this_page != req);
+
 	/* Lock the request! */
 	nfs_lock_request(req);
 
 	spin_lock(&inode->i_lock);
-	if (!nfsi->npages && NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
+	if (!nfsi->nrequests &&
+	    NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
 		inode->i_version++;
 	/*
 	 * Swap-space should not get truncated. Hence no need to plug the race
@@ -438,7 +687,12 @@
 		SetPagePrivate(req->wb_page);
 		set_page_private(req->wb_page, (unsigned long)req);
 	}
-	nfsi->npages++;
+	nfsi->nrequests++;
+	/* this a head request for a page group - mark it as having an
+	 * extra reference so sub groups can follow suit.
+	 * This flag also informs pgio layer when to bump nrequests when
+	 * adding subrequests. */
+	WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
 	kref_get(&req->wb_kref);
 	spin_unlock(&inode->i_lock);
 }
@@ -448,18 +702,31 @@
  */
 static void nfs_inode_remove_request(struct nfs_page *req)
 {
-	struct inode *inode = req->wb_context->dentry->d_inode;
+	struct inode *inode = d_inode(req->wb_context->dentry);
 	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs_page *head;
 
-	spin_lock(&inode->i_lock);
-	if (likely(!PageSwapCache(req->wb_page))) {
-		set_page_private(req->wb_page, 0);
-		ClearPagePrivate(req->wb_page);
-		clear_bit(PG_MAPPED, &req->wb_flags);
+	if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
+		head = req->wb_head;
+
+		spin_lock(&inode->i_lock);
+		if (likely(!PageSwapCache(head->wb_page))) {
+			set_page_private(head->wb_page, 0);
+			ClearPagePrivate(head->wb_page);
+			smp_mb__after_atomic();
+			wake_up_page(head->wb_page, PG_private);
+			clear_bit(PG_MAPPED, &head->wb_flags);
+		}
+		nfsi->nrequests--;
+		spin_unlock(&inode->i_lock);
+	} else {
+		spin_lock(&inode->i_lock);
+		nfsi->nrequests--;
+		spin_unlock(&inode->i_lock);
 	}
-	nfsi->npages--;
-	spin_unlock(&inode->i_lock);
-	nfs_release_request(req);
+
+	if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))
+		nfs_release_request(req);
 }
 
 static void
@@ -468,7 +735,60 @@
 	__set_page_dirty_nobuffers(req->wb_page);
 }
 
-#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
+/*
+ * nfs_page_search_commits_for_head_request_locked
+ *
+ * Search through commit lists on @inode for the head request for @page.
+ * Must be called while holding the inode (which is cinfo) lock.
+ *
+ * Returns the head request if found, or NULL if not found.
+ */
+static struct nfs_page *
+nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
+						struct page *page)
+{
+	struct nfs_page *freq, *t;
+	struct nfs_commit_info cinfo;
+	struct inode *inode = &nfsi->vfs_inode;
+
+	nfs_init_cinfo_from_inode(&cinfo, inode);
+
+	/* search through pnfs commit lists */
+	freq = pnfs_search_commit_reqs(inode, &cinfo, page);
+	if (freq)
+		return freq->wb_head;
+
+	/* Linearly search the commit list for the correct request */
+	list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
+		if (freq->wb_page == page)
+			return freq->wb_head;
+	}
+
+	return NULL;
+}
+
+/**
+ * nfs_request_add_commit_list_locked - add request to a commit list
+ * @req: pointer to a struct nfs_page
+ * @dst: commit list head
+ * @cinfo: holds list lock and accounting info
+ *
+ * This sets the PG_CLEAN bit, updates the cinfo count of
+ * number of outstanding requests requiring a commit as well as
+ * the MM page stats.
+ *
+ * The caller must hold the cinfo->lock, and the nfs_page lock.
+ */
+void
+nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
+			    struct nfs_commit_info *cinfo)
+{
+	set_bit(PG_CLEAN, &req->wb_flags);
+	nfs_list_add_request(req, dst);
+	cinfo->mds->ncommit++;
+}
+EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
+
 /**
  * nfs_request_add_commit_list - add request to a commit list
  * @req: pointer to a struct nfs_page
@@ -486,18 +806,10 @@
 nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
 			    struct nfs_commit_info *cinfo)
 {
-	set_bit(PG_CLEAN, &(req)->wb_flags);
 	spin_lock(cinfo->lock);
-	nfs_list_add_request(req, dst);
-	cinfo->mds->ncommit++;
+	nfs_request_add_commit_list_locked(req, dst, cinfo);
 	spin_unlock(cinfo->lock);
-	if (!cinfo->dreq) {
-		inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
-		inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
-			     BDI_RECLAIMABLE);
-		__mark_inode_dirty(req->wb_context->dentry->d_inode,
-				   I_DIRTY_DATASYNC);
-	}
+	nfs_mark_page_unstable(req->wb_page, cinfo);
 }
 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 
@@ -549,9 +861,9 @@
  */
 void
 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
-			struct nfs_commit_info *cinfo)
+			struct nfs_commit_info *cinfo, u32 ds_commit_idx)
 {
-	if (pnfs_mark_request_commit(req, lseg, cinfo))
+	if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
 		return;
 	nfs_request_add_commit_list(req, &cinfo->mds->list, cinfo);
 }
@@ -560,65 +872,33 @@
 nfs_clear_page_commit(struct page *page)
 {
 	dec_zone_page_state(page, NR_UNSTABLE_NFS);
-	dec_bdi_stat(page_file_mapping(page)->backing_dev_info, BDI_RECLAIMABLE);
+	dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
+		    WB_RECLAIMABLE);
 }
 
+/* Called holding inode (/cinfo) lock */
 static void
 nfs_clear_request_commit(struct nfs_page *req)
 {
 	if (test_bit(PG_CLEAN, &req->wb_flags)) {
-		struct inode *inode = req->wb_context->dentry->d_inode;
+		struct inode *inode = d_inode(req->wb_context->dentry);
 		struct nfs_commit_info cinfo;
 
 		nfs_init_cinfo_from_inode(&cinfo, inode);
 		if (!pnfs_clear_request_commit(req, &cinfo)) {
-			spin_lock(cinfo.lock);
 			nfs_request_remove_commit_list(req, &cinfo);
-			spin_unlock(cinfo.lock);
 		}
 		nfs_clear_page_commit(req->wb_page);
 	}
 }
 
-static inline
-int nfs_write_need_commit(struct nfs_write_data *data)
-{
-	if (data->verf.committed == NFS_DATA_SYNC)
-		return data->header->lseg == NULL;
-	return data->verf.committed != NFS_FILE_SYNC;
-}
-
-#else
-static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
-				      struct inode *inode)
-{
-}
-
-void nfs_init_cinfo(struct nfs_commit_info *cinfo,
-		    struct inode *inode,
-		    struct nfs_direct_req *dreq)
+int nfs_write_need_commit(struct nfs_pgio_header *hdr)
 {
+	if (hdr->verf.committed == NFS_DATA_SYNC)
+		return hdr->lseg == NULL;
+	return hdr->verf.committed != NFS_FILE_SYNC;
 }
 
-void
-nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
-			struct nfs_commit_info *cinfo)
-{
-}
-
-static void
-nfs_clear_request_commit(struct nfs_page *req)
-{
-}
-
-static inline
-int nfs_write_need_commit(struct nfs_write_data *data)
-{
-	return 0;
-}
-
-#endif
-
 static void nfs_write_completion(struct nfs_pgio_header *hdr)
 {
 	struct nfs_commit_info cinfo;
@@ -638,28 +918,24 @@
 			nfs_context_set_write_error(req->wb_context, hdr->error);
 			goto remove_req;
 		}
-		if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
-			nfs_mark_request_dirty(req);
-			goto next;
-		}
-		if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
-			memcpy(&req->wb_verf, &hdr->verf->verifier, sizeof(req->wb_verf));
-			nfs_mark_request_commit(req, hdr->lseg, &cinfo);
+		if (nfs_write_need_commit(hdr)) {
+			memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
+			nfs_mark_request_commit(req, hdr->lseg, &cinfo,
+				hdr->pgio_mirror_idx);
 			goto next;
 		}
 remove_req:
 		nfs_inode_remove_request(req);
 next:
 		nfs_unlock_request(req);
-		nfs_end_page_writeback(req->wb_page);
+		nfs_end_page_writeback(req);
 		nfs_release_request(req);
 	}
 out:
 	hdr->release(hdr);
 }
 
-#if  IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
-static unsigned long
+unsigned long
 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
 {
 	return cinfo->mds->ncommit;
@@ -715,19 +991,6 @@
 	return ret;
 }
 
-#else
-static unsigned long nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
-{
-	return 0;
-}
-
-int nfs_scan_commit(struct inode *inode, struct list_head *dst,
-		    struct nfs_commit_info *cinfo)
-{
-	return 0;
-}
-#endif
-
 /*
  * Search for an existing write request, and attempt to update
  * it to reflect a new dirty region on a given page.
@@ -752,10 +1015,14 @@
 	spin_lock(&inode->i_lock);
 
 	for (;;) {
-		req = nfs_page_find_request_locked(NFS_I(inode), page);
+		req = nfs_page_find_head_request_locked(NFS_I(inode), page);
 		if (req == NULL)
 			goto out_unlock;
 
+		/* should be handled by nfs_flush_incompatible */
+		WARN_ON_ONCE(req->wb_head != req);
+		WARN_ON_ONCE(req->wb_this_page != req);
+
 		rqend = req->wb_offset + req->wb_bytes;
 		/*
 		 * Tell the caller to flush out the request if
@@ -789,9 +1056,9 @@
 	else
 		req->wb_bytes = rqend - req->wb_offset;
 out_unlock:
-	spin_unlock(&inode->i_lock);
 	if (req)
 		nfs_clear_request_commit(req);
+	spin_unlock(&inode->i_lock);
 	return req;
 out_flushme:
 	spin_unlock(&inode->i_lock);
@@ -817,7 +1084,7 @@
 	req = nfs_try_to_update_request(inode, page, offset, bytes);
 	if (req != NULL)
 		goto out;
-	req = nfs_create_request(ctx, inode, page, offset, bytes);
+	req = nfs_create_request(ctx, page, NULL, offset, bytes);
 	if (IS_ERR(req))
 		goto out;
 	nfs_inode_add_request(inode, req);
@@ -835,7 +1102,7 @@
 		return PTR_ERR(req);
 	/* Update file length */
 	nfs_grow_file(page, offset, count);
-	nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
+	nfs_mark_uptodate(req);
 	nfs_mark_request_dirty(req);
 	nfs_unlock_and_release_request(req);
 	return 0;
@@ -845,6 +1112,7 @@
 {
 	struct nfs_open_context *ctx = nfs_file_open_context(file);
 	struct nfs_lock_context *l_ctx;
+	struct file_lock_context *flctx = file_inode(file)->i_flctx;
 	struct nfs_page	*req;
 	int do_flush, status;
 	/*
@@ -856,12 +1124,16 @@
 	 * dropped page.
 	 */
 	do {
-		req = nfs_page_find_request(page);
+		req = nfs_page_find_head_request(page);
 		if (req == NULL)
 			return 0;
 		l_ctx = req->wb_lock_context;
 		do_flush = req->wb_page != page || req->wb_context != ctx;
-		if (l_ctx) {
+		/* for now, flush if more than 1 request in page_group */
+		do_flush |= req->wb_this_page != req;
+		if (l_ctx && flctx &&
+		    !(list_empty_careful(&flctx->flc_posix) &&
+		      list_empty_careful(&flctx->flc_flock))) {
 			do_flush |= l_ctx->lockowner.l_owner != current->files
 				|| l_ctx->lockowner.l_pid != current->tgid;
 		}
@@ -874,20 +1146,103 @@
 }
 
 /*
+ * Avoid buffered writes when a open context credential's key would
+ * expire soon.
+ *
+ * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
+ *
+ * Return 0 and set a credential flag which triggers the inode to flush
+ * and performs  NFS_FILE_SYNC writes if the key will expired within
+ * RPC_KEY_EXPIRE_TIMEO.
+ */
+int
+nfs_key_timeout_notify(struct file *filp, struct inode *inode)
+{
+	struct nfs_open_context *ctx = nfs_file_open_context(filp);
+	struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
+
+	return rpcauth_key_timeout_notify(auth, ctx->cred);
+}
+
+/*
+ * Test if the open context credential key is marked to expire soon.
+ */
+bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx)
+{
+	return rpcauth_cred_key_to_expire(ctx->cred);
+}
+
+/*
  * If the page cache is marked as unsafe or invalid, then we can't rely on
  * the PageUptodate() flag. In this case, we will need to turn off
  * write optimisations that depend on the page contents being correct.
  */
 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
 {
+	struct nfs_inode *nfsi = NFS_I(inode);
+
 	if (nfs_have_delegated_attributes(inode))
 		goto out;
-	if (NFS_I(inode)->cache_validity & (NFS_INO_INVALID_DATA|NFS_INO_REVAL_PAGECACHE))
+	if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
+		return false;
+	smp_rmb();
+	if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
 		return false;
 out:
+	if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
+		return false;
 	return PageUptodate(page) != 0;
 }
 
+static bool
+is_whole_file_wrlock(struct file_lock *fl)
+{
+	return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
+			fl->fl_type == F_WRLCK;
+}
+
+/* If we know the page is up to date, and we're not using byte range locks (or
+ * if we have the whole file locked for writing), it may be more efficient to
+ * extend the write to cover the entire page in order to avoid fragmentation
+ * inefficiencies.
+ *
+ * If the file is opened for synchronous writes then we can just skip the rest
+ * of the checks.
+ */
+static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
+{
+	int ret;
+	struct file_lock_context *flctx = inode->i_flctx;
+	struct file_lock *fl;
+
+	if (file->f_flags & O_DSYNC)
+		return 0;
+	if (!nfs_write_pageuptodate(page, inode))
+		return 0;
+	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
+		return 1;
+	if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
+		       list_empty_careful(&flctx->flc_posix)))
+		return 1;
+
+	/* Check to see if there are whole file write locks */
+	ret = 0;
+	spin_lock(&flctx->flc_lock);
+	if (!list_empty(&flctx->flc_posix)) {
+		fl = list_first_entry(&flctx->flc_posix, struct file_lock,
+					fl_list);
+		if (is_whole_file_wrlock(fl))
+			ret = 1;
+	} else if (!list_empty(&flctx->flc_flock)) {
+		fl = list_first_entry(&flctx->flc_flock, struct file_lock,
+					fl_list);
+		if (fl->fl_type == F_WRLCK)
+			ret = 1;
+	}
+	spin_unlock(&flctx->flc_lock);
+	return ret;
+}
+
 /*
  * Update and possibly write a cached page of an NFS file.
  *
@@ -903,19 +1258,13 @@
 
 	nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 
-	dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
-		file->f_path.dentry->d_parent->d_name.name,
-		file->f_path.dentry->d_name.name, count,
-		(long long)(page_file_offset(page) + offset));
-
-	/* If we're not using byte range locks, and we know the page
-	 * is up to date, it may be more efficient to extend the write
-	 * to cover the entire page in order to avoid fragmentation
-	 * inefficiencies.
-	 */
-	if (nfs_write_pageuptodate(page, inode) &&
-			inode->i_flock == NULL &&
-			!(file->f_flags & O_DSYNC)) {
+	dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
+		file, count, (long long)(page_file_offset(page) + offset));
+
+	if (!count)
+		goto out;
+
+	if (nfs_can_extend_write(file, page, inode)) {
 		count = max(count + offset, nfs_page_length(page));
 		offset = 0;
 	}
@@ -925,7 +1274,7 @@
 		nfs_set_pageerror(page);
 	else
 		__set_page_dirty_nobuffers(page);
-
+out:
 	dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
 			status, (long long)i_size_read(inode));
 	return status;
@@ -942,123 +1291,18 @@
 	return RPC_PRIORITY_NORMAL;
 }
 
-int nfs_initiate_write(struct rpc_clnt *clnt,
-		       struct nfs_write_data *data,
-		       const struct rpc_call_ops *call_ops,
-		       int how, int flags)
+static void nfs_initiate_write(struct nfs_pgio_header *hdr,
+			       struct rpc_message *msg,
+			       const struct nfs_rpc_ops *rpc_ops,
+			       struct rpc_task_setup *task_setup_data, int how)
 {
-	struct inode *inode = data->header->inode;
 	int priority = flush_task_priority(how);
-	struct rpc_task *task;
-	struct rpc_message msg = {
-		.rpc_argp = &data->args,
-		.rpc_resp = &data->res,
-		.rpc_cred = data->header->cred,
-	};
-	struct rpc_task_setup task_setup_data = {
-		.rpc_client = clnt,
-		.task = &data->task,
-		.rpc_message = &msg,
-		.callback_ops = call_ops,
-		.callback_data = data,
-		.workqueue = nfsiod_workqueue,
-		.flags = RPC_TASK_ASYNC | flags,
-		.priority = priority,
-	};
-	int ret = 0;
-
-	/* Set up the initial task struct.  */
-	NFS_PROTO(inode)->write_setup(data, &msg);
-
-	dprintk("NFS: %5u initiated write call "
-		"(req %s/%lld, %u bytes @ offset %llu)\n",
-		data->task.tk_pid,
-		inode->i_sb->s_id,
-		(long long)NFS_FILEID(inode),
-		data->args.count,
-		(unsigned long long)data->args.offset);
-
-	task = rpc_run_task(&task_setup_data);
-	if (IS_ERR(task)) {
-		ret = PTR_ERR(task);
-		goto out;
-	}
-	if (how & FLUSH_SYNC) {
-		ret = rpc_wait_for_completion_task(task);
-		if (ret == 0)
-			ret = task->tk_status;
-	}
-	rpc_put_task(task);
-out:
-	return ret;
-}
-EXPORT_SYMBOL_GPL(nfs_initiate_write);
-
-/*
- * Set up the argument/result storage required for the RPC call.
- */
-static void nfs_write_rpcsetup(struct nfs_write_data *data,
-		unsigned int count, unsigned int offset,
-		int how, struct nfs_commit_info *cinfo)
-{
-	struct nfs_page *req = data->header->req;
-
-	/* Set up the RPC argument and reply structs
-	 * NB: take care not to mess about with data->commit et al. */
-
-	data->args.fh     = NFS_FH(data->header->inode);
-	data->args.offset = req_offset(req) + offset;
-	/* pnfs_set_layoutcommit needs this */
-	data->mds_offset = data->args.offset;
-	data->args.pgbase = req->wb_pgbase + offset;
-	data->args.pages  = data->pages.pagevec;
-	data->args.count  = count;
-	data->args.context = get_nfs_open_context(req->wb_context);
-	data->args.lock_context = req->wb_lock_context;
-	data->args.stable  = NFS_UNSTABLE;
-	switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
-	case 0:
-		break;
-	case FLUSH_COND_STABLE:
-		if (nfs_reqs_to_commit(cinfo))
-			break;
-	default:
-		data->args.stable = NFS_FILE_SYNC;
-	}
-
-	data->res.fattr   = &data->fattr;
-	data->res.count   = count;
-	data->res.verf    = &data->verf;
-	nfs_fattr_init(&data->fattr);
-}
 
-static int nfs_do_write(struct nfs_write_data *data,
-		const struct rpc_call_ops *call_ops,
-		int how)
-{
-	struct inode *inode = data->header->inode;
+	task_setup_data->priority = priority;
+	rpc_ops->write_setup(hdr, msg);
 
-	return nfs_initiate_write(NFS_CLIENT(inode), data, call_ops, how, 0);
-}
-
-static int nfs_do_multiple_writes(struct list_head *head,
-		const struct rpc_call_ops *call_ops,
-		int how)
-{
-	struct nfs_write_data *data;
-	int ret = 0;
-
-	while (!list_empty(head)) {
-		int ret2;
-
-		data = list_first_entry(head, struct nfs_write_data, list);
-		list_del_init(&data->list);
-		
-		ret2 = nfs_do_write(data, call_ops, how);
-		 if (ret == 0)
-			 ret = ret2;
-	}
-	return ret;
+	nfs4_state_protect_write(NFS_SERVER(hdr->inode)->nfs_client,
+				 &task_setup_data->rpc_client, msg, hdr);
 }
 
 /* If a nfs_flush_* function fails, it should remove reqs from @head and
@@ -1068,8 +1312,9 @@
 static void nfs_redirty_request(struct nfs_page *req)
 {
 	nfs_mark_request_dirty(req);
+	set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
 	nfs_unlock_request(req);
-	nfs_end_page_writeback(req->wb_page);
+	nfs_end_page_writeback(req);
 	nfs_release_request(req);
 }
 
@@ -1089,172 +1334,39 @@
 	.completion = nfs_write_completion,
 };
 
-static void nfs_flush_error(struct nfs_pageio_descriptor *desc,
-		struct nfs_pgio_header *hdr)
-{
-	set_bit(NFS_IOHDR_REDO, &hdr->flags);
-	while (!list_empty(&hdr->rpc_list)) {
-		struct nfs_write_data *data = list_first_entry(&hdr->rpc_list,
-				struct nfs_write_data, list);
-		list_del(&data->list);
-		nfs_writedata_release(data);
-	}
-	desc->pg_completion_ops->error_cleanup(&desc->pg_list);
-}
-
-/*
- * Generate multiple small requests to write out a single
- * contiguous dirty area on one page.
- */
-static int nfs_flush_multi(struct nfs_pageio_descriptor *desc,
-			   struct nfs_pgio_header *hdr)
+void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
+			       struct inode *inode, int ioflags, bool force_mds,
+			       const struct nfs_pgio_completion_ops *compl_ops)
 {
-	struct nfs_page *req = hdr->req;
-	struct page *page = req->wb_page;
-	struct nfs_write_data *data;
-	size_t wsize = desc->pg_bsize, nbytes;
-	unsigned int offset;
-	int requests = 0;
-	struct nfs_commit_info cinfo;
-
-	nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
-
-	if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
-	    (desc->pg_moreio || nfs_reqs_to_commit(&cinfo) ||
-	     desc->pg_count > wsize))
-		desc->pg_ioflags &= ~FLUSH_COND_STABLE;
-
-
-	offset = 0;
-	nbytes = desc->pg_count;
-	do {
-		size_t len = min(nbytes, wsize);
+	struct nfs_server *server = NFS_SERVER(inode);
+	const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
 
-		data = nfs_writedata_alloc(hdr, 1);
-		if (!data) {
-			nfs_flush_error(desc, hdr);
-			return -ENOMEM;
-		}
-		data->pages.pagevec[0] = page;
-		nfs_write_rpcsetup(data, len, offset, desc->pg_ioflags, &cinfo);
-		list_add(&data->list, &hdr->rpc_list);
-		requests++;
-		nbytes -= len;
-		offset += len;
-	} while (nbytes != 0);
-	nfs_list_remove_request(req);
-	nfs_list_add_request(req, &hdr->pages);
-	desc->pg_rpc_callops = &nfs_write_common_ops;
-	return 0;
-}
-
-/*
- * Create an RPC task for the given write request and kick it.
- * The page must have been locked by the caller.
- *
- * It may happen that the page we're passed is not marked dirty.
- * This is the case if nfs_updatepage detects a conflicting request
- * that has been written but not committed.
- */
-static int nfs_flush_one(struct nfs_pageio_descriptor *desc,
-			 struct nfs_pgio_header *hdr)
-{
-	struct nfs_page		*req;
-	struct page		**pages;
-	struct nfs_write_data	*data;
-	struct list_head *head = &desc->pg_list;
-	struct nfs_commit_info cinfo;
-
-	data = nfs_writedata_alloc(hdr, nfs_page_array_len(desc->pg_base,
-							   desc->pg_count));
-	if (!data) {
-		nfs_flush_error(desc, hdr);
-		return -ENOMEM;
-	}
-
-	nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
-	pages = data->pages.pagevec;
-	while (!list_empty(head)) {
-		req = nfs_list_entry(head->next);
-		nfs_list_remove_request(req);
-		nfs_list_add_request(req, &hdr->pages);
-		*pages++ = req->wb_page;
-	}
-
-	if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
-	    (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
-		desc->pg_ioflags &= ~FLUSH_COND_STABLE;
-
-	/* Set up the argument struct */
-	nfs_write_rpcsetup(data, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
-	list_add(&data->list, &hdr->rpc_list);
-	desc->pg_rpc_callops = &nfs_write_common_ops;
-	return 0;
+#ifdef CONFIG_NFS_V4_1
+	if (server->pnfs_curr_ld && !force_mds)
+		pg_ops = server->pnfs_curr_ld->pg_write_ops;
+#endif
+	nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
+			server->wsize, ioflags);
 }
+EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
 
-int nfs_generic_flush(struct nfs_pageio_descriptor *desc,
-		      struct nfs_pgio_header *hdr)
+void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
 {
-	if (desc->pg_bsize < PAGE_CACHE_SIZE)
-		return nfs_flush_multi(desc, hdr);
-	return nfs_flush_one(desc, hdr);
-}
-EXPORT_SYMBOL_GPL(nfs_generic_flush);
+	struct nfs_pgio_mirror *mirror;
 
-static int nfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
-{
-	struct nfs_write_header *whdr;
-	struct nfs_pgio_header *hdr;
-	int ret;
+	if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
+		pgio->pg_ops->pg_cleanup(pgio);
 
-	whdr = nfs_writehdr_alloc();
-	if (!whdr) {
-		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
-		return -ENOMEM;
-	}
-	hdr = &whdr->header;
-	nfs_pgheader_init(desc, hdr, nfs_writehdr_free);
-	atomic_inc(&hdr->refcnt);
-	ret = nfs_generic_flush(desc, hdr);
-	if (ret == 0)
-		ret = nfs_do_multiple_writes(&hdr->rpc_list,
-					     desc->pg_rpc_callops,
-					     desc->pg_ioflags);
-	if (atomic_dec_and_test(&hdr->refcnt))
-		hdr->completion_ops->completion(hdr);
-	return ret;
-}
+	pgio->pg_ops = &nfs_pgio_rw_ops;
 
-static const struct nfs_pageio_ops nfs_pageio_write_ops = {
-	.pg_test = nfs_generic_pg_test,
-	.pg_doio = nfs_generic_pg_writepages,
-};
+	nfs_pageio_stop_mirroring(pgio);
 
-void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
-			       struct inode *inode, int ioflags,
-			       const struct nfs_pgio_completion_ops *compl_ops)
-{
-	nfs_pageio_init(pgio, inode, &nfs_pageio_write_ops, compl_ops,
-				NFS_SERVER(inode)->wsize, ioflags);
-}
-EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
-
-void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
-{
-	pgio->pg_ops = &nfs_pageio_write_ops;
-	pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
+	mirror = &pgio->pg_mirrors[0];
+	mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
 
 
-void nfs_write_prepare(struct rpc_task *task, void *calldata)
-{
-	struct nfs_write_data *data = calldata;
-	NFS_PROTO(data->header->inode)->write_rpc_prepare(task, data);
-	if (unlikely(test_bit(NFS_CONTEXT_BAD, &data->args.context->flags)))
-		rpc_exit(task, -EIO);
-}
-
 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
 {
 	struct nfs_commit_data *data = calldata;
@@ -1263,58 +1375,72 @@
 }
 
 /*
- * Handle a write reply that flushes a whole page.
- *
- * FIXME: There is an inherent race with invalidate_inode_pages and
- *	  writebacks since the page->count is kept > 1 for as long
- *	  as the page has a write request pending.
+ * Special version of should_remove_suid() that ignores capabilities.
  */
-static void nfs_writeback_done_common(struct rpc_task *task, void *calldata)
+static int nfs_should_remove_suid(const struct inode *inode)
 {
-	struct nfs_write_data	*data = calldata;
+	umode_t mode = inode->i_mode;
+	int kill = 0;
+
+	/* suid always must be killed */
+	if (unlikely(mode & S_ISUID))
+		kill = ATTR_KILL_SUID;
+
+	/*
+	 * sgid without any exec bits is just a mandatory locking mark; leave
+	 * it alone.  If some exec bits are set, it's a real sgid; kill it.
+	 */
+	if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
+		kill |= ATTR_KILL_SGID;
+
+	if (unlikely(kill && S_ISREG(mode)))
+		return kill;
 
-	nfs_writeback_done(task, data);
+	return 0;
 }
 
-static void nfs_writeback_release_common(void *calldata)
+static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
+		struct nfs_fattr *fattr)
 {
-	struct nfs_write_data	*data = calldata;
-	struct nfs_pgio_header *hdr = data->header;
-	int status = data->task.tk_status;
+	struct nfs_pgio_args *argp = &hdr->args;
+	struct nfs_pgio_res *resp = &hdr->res;
+	u64 size = argp->offset + resp->count;
+
+	if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
+		fattr->size = size;
+	if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
+		fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
+		return;
+	}
+	if (size != fattr->size)
+		return;
+	/* Set attribute barrier */
+	nfs_fattr_set_barrier(fattr);
+	/* ...and update size */
+	fattr->valid |= NFS_ATTR_FATTR_SIZE;
+}
 
-	if ((status >= 0) && nfs_write_need_commit(data)) {
-		spin_lock(&hdr->lock);
-		if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags))
-			; /* Do nothing */
-		else if (!test_and_set_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags))
-			memcpy(hdr->verf, &data->verf, sizeof(*hdr->verf));
-		else if (memcmp(hdr->verf, &data->verf, sizeof(*hdr->verf)))
-			set_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags);
-		spin_unlock(&hdr->lock);
-	}
-	nfs_writedata_release(data);
-}
-
-static const struct rpc_call_ops nfs_write_common_ops = {
-	.rpc_call_prepare = nfs_write_prepare,
-	.rpc_call_done = nfs_writeback_done_common,
-	.rpc_release = nfs_writeback_release_common,
-};
+void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
+{
+	struct nfs_fattr *fattr = &hdr->fattr;
+	struct inode *inode = hdr->inode;
 
+	spin_lock(&inode->i_lock);
+	nfs_writeback_check_extend(hdr, fattr);
+	nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
+	spin_unlock(&inode->i_lock);
+}
+EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
 
 /*
  * This function is called when the WRITE call is complete.
  */
-void nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
+static int nfs_writeback_done(struct rpc_task *task,
+			      struct nfs_pgio_header *hdr,
+			      struct inode *inode)
 {
-	struct nfs_writeargs	*argp = &data->args;
-	struct nfs_writeres	*resp = &data->res;
-	struct inode		*inode = data->header->inode;
 	int status;
 
-	dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
-		task->tk_pid, task->tk_status);
-
 	/*
 	 * ->write_done will attempt to use post-op attributes to detect
 	 * conflicting writes by other clients.  A strict interpretation
@@ -1322,13 +1448,13 @@
 	 * another writer had changed the file, but some applications
 	 * depend on tighter cache coherency when writing.
 	 */
-	status = NFS_PROTO(inode)->write_done(task, data);
+	status = NFS_PROTO(inode)->write_done(task, hdr);
 	if (status != 0)
-		return;
-	nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
+		return status;
+	nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
 
-#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
-	if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
+	if (hdr->res.verf->committed < hdr->args.stable &&
+	    task->tk_status >= 0) {
 		/* We tried a write call, but the server did not
 		 * commit data to stable storage even though we
 		 * requested it.
@@ -1344,18 +1470,31 @@
 			dprintk("NFS:       faulty NFS server %s:"
 				" (committed = %d) != (stable = %d)\n",
 				NFS_SERVER(inode)->nfs_client->cl_hostname,
-				resp->verf->committed, argp->stable);
+				hdr->res.verf->committed, hdr->args.stable);
 			complain = jiffies + 300 * HZ;
 		}
 	}
-#endif
-	if (task->tk_status < 0)
-		nfs_set_pgio_error(data->header, task->tk_status, argp->offset);
-	else if (resp->count < argp->count) {
+
+	/* Deal with the suid/sgid bit corner case */
+	if (nfs_should_remove_suid(inode))
+		nfs_mark_for_revalidate(inode);
+	return 0;
+}
+
+/*
+ * This function is called when the WRITE call is complete.
+ */
+static void nfs_writeback_result(struct rpc_task *task,
+				 struct nfs_pgio_header *hdr)
+{
+	struct nfs_pgio_args	*argp = &hdr->args;
+	struct nfs_pgio_res	*resp = &hdr->res;
+
+	if (resp->count < argp->count) {
 		static unsigned long    complain;
 
 		/* This a short write! */
-		nfs_inc_stats(inode, NFSIOS_SHORTWRITE);
+		nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
 
 		/* Has the server at least made some progress? */
 		if (resp->count == 0) {
@@ -1365,14 +1504,21 @@
 				       argp->count);
 				complain = jiffies + 300 * HZ;
 			}
-			nfs_set_pgio_error(data->header, -EIO, argp->offset);
+			nfs_set_pgio_error(hdr, -EIO, argp->offset);
 			task->tk_status = -EIO;
 			return;
 		}
+
+		/* For non rpc-based layout drivers, retry-through-MDS */
+		if (!task->tk_ops) {
+			hdr->pnfs_error = -EAGAIN;
+			return;
+		}
+
 		/* Was this an NFSv2 write or an NFSv3 stable write? */
 		if (resp->verf->committed != NFS_UNSTABLE) {
 			/* Resend from where the server left off */
-			data->mds_offset += resp->count;
+			hdr->mds_offset += resp->count;
 			argp->offset += resp->count;
 			argp->pgbase += resp->count;
 			argp->count -= resp->count;
@@ -1387,7 +1533,6 @@
 }
 
 
-#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
 static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)
 {
 	int ret;
@@ -1406,7 +1551,7 @@
 static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
 {
 	clear_bit(NFS_INO_COMMIT, &nfsi->flags);
-	smp_mb__after_clear_bit();
+	smp_mb__after_atomic();
 	wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);
 }
 
@@ -1418,6 +1563,7 @@
 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
 
 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
+			const struct nfs_rpc_ops *nfs_ops,
 			const struct rpc_call_ops *call_ops,
 			int how, int flags)
 {
@@ -1439,9 +1585,12 @@
 		.priority = priority,
 	};
 	/* Set up the initial task struct.  */
-	NFS_PROTO(data->inode)->commit_setup(data, &msg);
+	nfs_ops->commit_setup(data, &msg);
 
-	dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
+	dprintk("NFS: initiated commit call\n");
+
+	nfs4_state_protect(NFS_SERVER(data->inode)->nfs_client,
+		NFS_SP4_MACH_CRED_COMMIT, &task_setup_data.rpc_client, &msg);
 
 	task = rpc_run_task(&task_setup_data);
 	if (IS_ERR(task))
@@ -1453,6 +1602,18 @@
 }
 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
 
+static loff_t nfs_get_lwb(struct list_head *head)
+{
+	loff_t lwb = 0;
+	struct nfs_page *req;
+
+	list_for_each_entry(req, head, wb_list)
+		if (lwb < (req_offset(req) + req->wb_bytes))
+			lwb = req_offset(req) + req->wb_bytes;
+
+	return lwb;
+}
+
 /*
  * Set up the argument/result storage required for the RPC call.
  */
@@ -1462,7 +1623,7 @@
 		     struct nfs_commit_info *cinfo)
 {
 	struct nfs_page *first = nfs_list_entry(head->next);
-	struct inode *inode = first->wb_context->dentry->d_inode;
+	struct inode *inode = d_inode(first->wb_context->dentry);
 
 	/* Set up the RPC argument and reply structs
 	 * NB: take care not to mess about with data->commit et al. */
@@ -1472,6 +1633,9 @@
 	data->inode	  = inode;
 	data->cred	  = first->wb_context->cred;
 	data->lseg	  = lseg; /* reference transferred */
+	/* only set lwb for pnfs commit */
+	if (lseg)
+		data->lwb = nfs_get_lwb(&data->pages);
 	data->mds_ops     = &nfs_commit_ops;
 	data->completion_ops = cinfo->completion_ops;
 	data->dreq	  = cinfo->dreq;
@@ -1489,19 +1653,17 @@
 
 void nfs_retry_commit(struct list_head *page_list,
 		      struct pnfs_layout_segment *lseg,
-		      struct nfs_commit_info *cinfo)
+		      struct nfs_commit_info *cinfo,
+		      u32 ds_commit_idx)
 {
 	struct nfs_page *req;
 
 	while (!list_empty(page_list)) {
 		req = nfs_list_entry(page_list->next);
 		nfs_list_remove_request(req);
-		nfs_mark_request_commit(req, lseg, cinfo);
-		if (!cinfo->dreq) {
-			dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
-			dec_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
-				     BDI_RECLAIMABLE);
-		}
+		nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
+		if (!cinfo->dreq)
+			nfs_clear_page_commit(req->wb_page);
 		nfs_unlock_and_release_request(req);
 	}
 }
@@ -1524,10 +1686,10 @@
 	/* Set up the argument struct */
 	nfs_init_commit(data, head, NULL, cinfo);
 	atomic_inc(&cinfo->mds->rpcs_out);
-	return nfs_initiate_commit(NFS_CLIENT(inode), data, data->mds_ops,
-				   how, 0);
+	return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
+				   data->mds_ops, how, 0);
  out_bad:
-	nfs_retry_commit(head, NULL, cinfo);
+	nfs_retry_commit(head, NULL, cinfo, 0);
 	cinfo->completion_ops->error_cleanup(NFS_I(inode));
 	return -ENOMEM;
 }
@@ -1551,15 +1713,16 @@
 	struct nfs_page	*req;
 	int status = data->task.tk_status;
 	struct nfs_commit_info cinfo;
+	struct nfs_server *nfss;
 
 	while (!list_empty(&data->pages)) {
 		req = nfs_list_entry(data->pages.next);
 		nfs_list_remove_request(req);
 		nfs_clear_page_commit(req->wb_page);
 
-		dprintk("NFS:       commit (%s/%lld %d@%lld)",
+		dprintk("NFS:       commit (%s/%llu %d@%lld)",
 			req->wb_context->dentry->d_sb->s_id,
-			(long long)NFS_FILEID(req->wb_context->dentry->d_inode),
+			(unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)),
 			req->wb_bytes,
 			(long long)req_offset(req));
 		if (status < 0) {
@@ -1584,6 +1747,10 @@
 	next:
 		nfs_unlock_and_release_request(req);
 	}
+	nfss = NFS_SERVER(data->inode);
+	if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
+		clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
+
 	nfs_init_cinfo(&cinfo, data->inode, data->dreq);
 	if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
 		nfs_commit_clear_lock(NFS_I(data->inode));
@@ -1639,7 +1806,7 @@
 			return error;
 		if (!may_wait)
 			goto out_mark_dirty;
-		error = wait_on_bit(&NFS_I(inode)->flags,
+		error = wait_on_bit_action(&NFS_I(inode)->flags,
 				NFS_INO_COMMIT,
 				nfs_wait_bit_killable,
 				TASK_KILLABLE);
@@ -1658,7 +1825,7 @@
 	return res;
 }
 
-static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
+int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
 	int flags = FLUSH_SYNC;
@@ -1672,7 +1839,7 @@
 		/* Don't commit yet if this is a non-blocking flush and there
 		 * are a lot of outstanding writes for this mapping.
 		 */
-		if (nfsi->commit_info.ncommit <= (nfsi->npages >> 1))
+		if (nfsi->commit_info.ncommit <= (nfsi->nrequests >> 1))
 			goto out_mark_dirty;
 
 		/* don't wait for the COMMIT response */
@@ -1693,17 +1860,6 @@
 	__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 	return ret;
 }
-#else
-static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_control *wbc)
-{
-	return 0;
-}
-#endif
-
-int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
-{
-	return nfs_commit_unstable_pages(inode, wbc);
-}
 EXPORT_SYMBOL_GPL(nfs_write_inode);
 
 /*
@@ -1711,14 +1867,22 @@
  */
 int nfs_wb_all(struct inode *inode)
 {
-	struct writeback_control wbc = {
-		.sync_mode = WB_SYNC_ALL,
-		.nr_to_write = LONG_MAX,
-		.range_start = 0,
-		.range_end = LLONG_MAX,
-	};
+	int ret;
+
+	trace_nfs_writeback_inode_enter(inode);
+
+	ret = filemap_write_and_wait(inode->i_mapping);
+	if (ret)
+		goto out;
+	ret = nfs_commit_inode(inode, FLUSH_SYNC);
+	if (ret < 0)
+		goto out;
+	pnfs_sync_inode(inode, true);
+	ret = 0;
 
-	return sync_inode(inode, &wbc);
+out:
+	trace_nfs_writeback_inode_exit(inode, ret);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(nfs_wb_all);
 
@@ -1727,27 +1891,23 @@
 	struct nfs_page *req;
 	int ret = 0;
 
-	for (;;) {
-		wait_on_page_writeback(page);
-		req = nfs_page_find_request(page);
-		if (req == NULL)
-			break;
-		if (nfs_lock_request(req)) {
-			nfs_clear_request_commit(req);
-			nfs_inode_remove_request(req);
-			/*
-			 * In case nfs_inode_remove_request has marked the
-			 * page as being dirty
-			 */
-			cancel_dirty_page(page, PAGE_CACHE_SIZE);
-			nfs_unlock_and_release_request(req);
-			break;
-		}
-		ret = nfs_wait_on_request(req);
-		nfs_release_request(req);
-		if (ret < 0)
-			break;
+	wait_on_page_writeback(page);
+
+	/* blocking call to cancel all requests and join to a single (head)
+	 * request */
+	req = nfs_lock_and_join_requests(page, false);
+
+	if (IS_ERR(req)) {
+		ret = PTR_ERR(req);
+	} else if (req) {
+		/* all requests from this page have been cancelled by
+		 * nfs_lock_and_join_requests, so just remove the head
+		 * request from the inode / page_private pointer and
+		 * release it */
+		nfs_inode_remove_request(req);
+		nfs_unlock_and_release_request(req);
 	}
+
 	return ret;
 }
 
@@ -1766,6 +1926,8 @@
 	};
 	int ret;
 
+	trace_nfs_writeback_page_enter(inode);
+
 	for (;;) {
 		wait_on_page_writeback(page);
 		if (clear_page_dirty_for_io(page)) {
@@ -1774,14 +1936,15 @@
 				goto out_error;
 			continue;
 		}
+		ret = 0;
 		if (!PagePrivate(page))
 			break;
 		ret = nfs_commit_inode(inode, FLUSH_SYNC);
 		if (ret < 0)
 			goto out_error;
 	}
-	return 0;
 out_error:
+	trace_nfs_writeback_page_exit(inode, ret);
 	return ret;
 }
 
@@ -1810,7 +1973,7 @@
 int __init nfs_init_writepagecache(void)
 {
 	nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
-					     sizeof(struct nfs_write_header),
+					     sizeof(struct nfs_pgio_header),
 					     0, SLAB_HWCACHE_ALIGN,
 					     NULL);
 	if (nfs_wdata_cachep == NULL)
@@ -1872,3 +2035,11 @@
 	kmem_cache_destroy(nfs_wdata_cachep);
 }
 
+static const struct nfs_rw_ops nfs_rw_write_ops = {
+	.rw_mode		= FMODE_WRITE,
+	.rw_alloc_header	= nfs_writehdr_alloc,
+	.rw_free_header		= nfs_writehdr_free,
+	.rw_done		= nfs_writeback_done,
+	.rw_result		= nfs_writeback_result,
+	.rw_initiate		= nfs_initiate_write,
+};