diff mbox series

[RFC,3/3] NFS: Convert nfs_read_folio and nfs_readahead to netfs APIs

Message ID 20220824093501.384755-4-dwysocha@redhat.com (mailing list archive)
State New, archived
Headers show
Series Convert NFS to the new netfs API | expand

Commit Message

David Wysochanski Aug. 24, 2022, 9:35 a.m. UTC
Convert the NFS non-direct read code paths to corresponding netfs APIs.
The netfs API defines struct netfs_request_ops which must be filled
in by the network filesystem.  For NFS, we only need to define 4 of
the functions, the main one being the issue_read() function.
The issue_read() function is called by the netfs layer when a read
cannot be fulfilled locally, and must be sent to the server (either
the cache is not active, or it is active but the data is not available).
Once the read from the server is complete, netfs requires a call to
netfs_subreq_terminated() which conveys either how many bytes were read
successfully, or an error.  Note that issue_read() is called with a
structure, netfs_io_subrequest, which defines the IO requested, and
contains a start and a length (both in bytes), and assumes the underlying
netfs will return a either an error on the whole region, or the number
of bytes successfully read (a short read).

The NFS pgio API layer is page based, and there is no way for the caller
of these APIs to know how many RPCs will be sent and how the pages
will be broken up into underlying RPCs, each of which will have their
own return code.  Thus, NFS needs some way to accommodate the netfs
API requirement on the single response to the whole request, while also
minimizing disruptive changes to the NFS pgio layer.  The approach taken
with this patch is to allocate a small structure for each call to
nfs_issue_read() to keep some accounting information for the outstanding
RPCs, as well as the final error value or the number of bytes successfully
read.  The accounting data is updated inside the pgio layer, when a
nfs_pgio_header contains a valid pointer to this data.  In the NFS read
completion routine, nfs_read_completion(), the final error value and
bytes read is updated, and the accounting data is used to determine
whether this completion represents the last RPC.  If this is the last RPC,
call netfs_subreq_terminated() with the final error value or the number
of bytes transferred.

Note that the final disposition of a netfs_io_subrequest is given by
transferred_or_error parameter to netfs_subreq_terminated(), which
conveys either the number of bytes transferred (all RPCs were successful),
or an error (one or more RPCs completed with an error).  In the error
case, the value of transferred_or_error is set to the error in the RPC
that completed last.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---
 fs/nfs/fscache.c         | 175 ++++++++++++++++++---------------------
 fs/nfs/fscache.h         |  68 ++++++++-------
 fs/nfs/inode.c           |   2 +
 fs/nfs/internal.h        |   8 ++
 fs/nfs/pagelist.c        |  14 ++++
 fs/nfs/read.c            |  99 +++++++---------------
 include/linux/nfs_page.h |   1 +
 include/linux/nfs_xdr.h  |   1 +
 8 files changed, 172 insertions(+), 196 deletions(-)
diff mbox series

Patch

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index a6fc1c8b6644..8e1f5c2ed8f2 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -15,6 +15,9 @@ 
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/iversion.h>
+#include <linux/xarray.h>
+#include <linux/fscache.h>
+#include <linux/netfs.h>
 
 #include "internal.h"
 #include "iostat.h"
@@ -235,112 +238,96 @@  void nfs_fscache_release_file(struct inode *inode, struct file *filp)
 	fscache_unuse_cookie(cookie, &auxdata, &i_size);
 }
 
-/*
- * Fallback page reading interface.
- */
-static int fscache_fallback_read_page(struct inode *inode, struct page *page)
+
+atomic_t nfs_netfs_debug_id;
+static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
 {
-	struct netfs_cache_resources cres;
-	struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
-	struct iov_iter iter;
-	struct bio_vec bvec[1];
-	int ret;
-
-	memset(&cres, 0, sizeof(cres));
-	bvec[0].bv_page		= page;
-	bvec[0].bv_offset	= 0;
-	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
-
-	ret = fscache_begin_read_operation(&cres, cookie);
-	if (ret < 0)
-		return ret;
-
-	ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
-			   NULL, NULL);
-	fscache_end_operation(&cres);
-	return ret;
+	struct nfs_open_context *ctx;
+
+	if (file == NULL) {
+		ctx = nfs_find_open_context(rreq->inode, NULL, FMODE_READ);
+		if (!ctx)
+			return -ENOMEM;
+	} else
+		ctx = get_nfs_open_context(nfs_file_open_context(file));
+
+	rreq->netfs_priv = ctx;
+
+	if (netfs_i_cookie(&NFS_I(rreq->inode)->netfs))
+		rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
+
+	return 0;
 }
 
-/*
- * Fallback page writing interface.
- */
-static int fscache_fallback_write_page(struct inode *inode, struct page *page,
-				       bool no_space_allocated_yet)
+static void nfs_netfs_free_request(struct netfs_io_request *rreq)
 {
-	struct netfs_cache_resources cres;
-	struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
-	struct iov_iter iter;
-	struct bio_vec bvec[1];
-	loff_t start = page_offset(page);
-	size_t len = PAGE_SIZE;
-	int ret;
-
-	memset(&cres, 0, sizeof(cres));
-	bvec[0].bv_page		= page;
-	bvec[0].bv_offset	= 0;
-	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
-
-	ret = fscache_begin_write_operation(&cres, cookie);
-	if (ret < 0)
-		return ret;
-
-	ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
-				      no_space_allocated_yet);
-	if (ret == 0)
-		ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
-	fscache_end_operation(&cres);
-	return ret;
+	put_nfs_open_context(rreq->netfs_priv);
 }
 
-/*
- * Retrieve a page from fscache
- */
-int __nfs_fscache_read_page(struct inode *inode, struct page *page)
+static inline int nfs_begin_cache_operation(struct netfs_io_request *rreq)
 {
-	int ret;
-
-	trace_nfs_fscache_read_page(inode, page);
-	if (PageChecked(page)) {
-		ClearPageChecked(page);
-		ret = 1;
-		goto out;
-	}
-
-	ret = fscache_fallback_read_page(inode, page);
-	if (ret < 0) {
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
-		SetPageChecked(page);
-		goto out;
-	}
-
-	/* Read completed synchronously */
-	nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
-	SetPageUptodate(page);
-	ret = 0;
-out:
-	trace_nfs_fscache_read_page_exit(inode, page, ret);
-	return ret;
+	return fscache_begin_read_operation(&rreq->cache_resources,
+					    netfs_i_cookie(&NFS_I(rreq->inode)->netfs));
 }
 
-/*
- * Store a newly fetched page in fscache.  We can be certain there's no page
- * stored in the cache as yet otherwise we would've read it from there.
- */
-void __nfs_fscache_write_page(struct inode *inode, struct page *page)
+static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
 {
-	int ret;
+	struct nfs_netfs_io_data *netfs;
+
+	netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
+	if (!netfs)
+		return NULL;
+	netfs->sreq = sreq;
+	refcount_set(&netfs->refcount, 1);
+	return netfs;
+}
 
-	trace_nfs_fscache_write_page(inode, page);
+static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
+{
+	size_t	rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
 
-	ret = fscache_fallback_write_page(inode, page, true);
+	sreq->len = min(sreq->len, rsize);
+	return true;
+}
 
-	if (ret != 0) {
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
-	} else {
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
+static void nfs_issue_read(struct netfs_io_subrequest *sreq)
+{
+	struct nfs_pageio_descriptor pgio;
+	struct inode *inode = sreq->rreq->inode;
+	struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
+	struct page *page;
+	int err;
+	pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
+	pgoff_t last = ((sreq->start + sreq->len -
+			 sreq->transferred - 1) >> PAGE_SHIFT);
+	XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
+
+	nfs_pageio_init_read(&pgio, inode, false,
+			     &nfs_async_read_completion_ops);
+
+	pgio.pg_netfs = nfs_netfs_alloc(sreq); /* used in completion */
+	if (!pgio.pg_netfs)
+		return netfs_subreq_terminated(sreq, -ENOMEM, false);
+
+	xas_lock(&xas);
+	xas_for_each(&xas, page, last) {
+		/* nfs_pageio_add_page() may schedule() due to pNFS layout and other RPCs  */
+		xas_pause(&xas);
+		xas_unlock(&xas);
+		err = nfs_pageio_add_page(&pgio, ctx, page);
+		if (err < 0)
+			return netfs_subreq_terminated(sreq, err, false);
+		xas_lock(&xas);
 	}
-	trace_nfs_fscache_write_page_exit(inode, page, ret);
+	xas_unlock(&xas);
+	nfs_pageio_complete_read(&pgio);
+	nfs_netfs_put(pgio.pg_netfs);
 }
+
+const struct netfs_request_ops nfs_netfs_ops = {
+	.init_request		= nfs_netfs_init_request,
+	.free_request		= nfs_netfs_free_request,
+	.begin_cache_operation	= nfs_begin_cache_operation,
+	.issue_read		= nfs_issue_read,
+	.clamp_length		= nfs_netfs_clamp_length
+};
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 38614ed8f951..90a20ce9c432 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -34,6 +34,41 @@  struct nfs_fscache_inode_auxdata {
 	u64	change_attr;
 };
 
+struct nfs_netfs_io_data {
+	refcount_t			refcount;
+	struct netfs_io_subrequest	*sreq;
+
+	/*
+	 * NFS may split a netfs_io_subrequest into multiple RPCs, each
+	 * with their own read completion.  In netfs, we can only call
+	 * netfs_subreq_terminated() once for each subrequest.  So we
+	 * must keep track of the rpcs and rpc_byte_count for what has
+	 * been submitted, and only call netfs via netfs_subreq_terminated()
+	 * when the final RPC has completed.
+	 */
+	atomic_t	rpcs;
+	unsigned long	rpc_byte_count;
+
+	/*
+	 * Final dispostion of the netfs_io_subrequest, sent in
+	 * netfs_subreq_terminated()
+	 */
+	ssize_t		transferred;
+	int		error;
+};
+
+static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)
+{
+	refcount_inc(&netfs->refcount);
+}
+
+static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
+{
+	if (!refcount_dec_and_test(&netfs->refcount))
+		return;
+	kfree(netfs);
+}
+
 /*
  * fscache.c
  */
@@ -45,43 +80,17 @@  extern void nfs_fscache_clear_inode(struct inode *);
 extern void nfs_fscache_open_file(struct inode *, struct file *);
 extern void nfs_fscache_release_file(struct inode *, struct file *);
 
-extern int __nfs_fscache_read_page(struct inode *, struct page *);
-extern void __nfs_fscache_write_page(struct inode *, struct page *);
-
 static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
 {
 	if (folio_test_fscache(folio)) {
 		if (current_is_kswapd() || !(gfp & __GFP_FS))
 			return false;
 		folio_wait_fscache(folio);
-		fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
-		nfs_inc_fscache_stats(folio->mapping->host,
-				      NFSIOS_FSCACHE_PAGES_UNCACHED);
 	}
+	fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)->netfs));
 	return true;
 }
 
-/*
- * Retrieve a page from an inode data storage object.
- */
-static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
-{
-	if (netfs_inode(inode)->cache)
-		return __nfs_fscache_read_page(inode, page);
-	return -ENOBUFS;
-}
-
-/*
- * Store a page newly fetched from the server in an inode data storage object
- * in the cache.
- */
-static inline void nfs_fscache_write_page(struct inode *inode,
-					   struct page *page)
-{
-	if (netfs_inode(inode)->cache)
-		__nfs_fscache_write_page(inode, page);
-}
-
 static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
 					      struct inode *inode)
 {
@@ -130,11 +139,6 @@  static inline bool nfs_fscache_release_folio(struct folio *folio, gfp_t gfp)
 {
 	return true; /* may release folio */
 }
-static inline int nfs_fscache_read_page(struct inode *inode, struct page *page)
-{
-	return -ENOBUFS;
-}
-static inline void nfs_fscache_write_page(struct inode *inode, struct page *page) {}
 static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
 
 static inline const char *nfs_server_fscache_state(struct nfs_server *server)
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 3acddec41ba7..dea13500003f 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -2248,6 +2248,8 @@  struct inode *nfs_alloc_inode(struct super_block *sb)
 #ifdef CONFIG_NFS_V4_2
 	nfsi->xattr_cache = NULL;
 #endif
+	netfs_inode_init(&nfsi->netfs, &nfs_netfs_ops);
+
 	return &nfsi->netfs.inode;
 }
 EXPORT_SYMBOL_GPL(nfs_alloc_inode);
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 29cfee4660c5..2895e9ada22e 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -453,6 +453,9 @@  extern void nfs_sb_deactive(struct super_block *sb);
 extern int nfs_client_for_each_server(struct nfs_client *clp,
 				      int (*fn)(struct nfs_server *, void *),
 				      void *data);
+/* fscache.c */
+extern const struct netfs_request_ops nfs_netfs_ops;
+
 /* io.c */
 extern void nfs_start_io_read(struct inode *inode);
 extern void nfs_end_io_read(struct inode *inode);
@@ -482,9 +485,14 @@  extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
 
 struct nfs_pgio_completion_ops;
 /* read.c */
+extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
 extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
 			struct inode *inode, bool force_mds,
 			const struct nfs_pgio_completion_ops *compl_ops);
+extern int nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
+			       struct nfs_open_context *ctx,
+			       struct page *page);
+extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio);
 extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
 extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
 
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 317cedfa52bf..93458da76e32 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -25,6 +25,7 @@ 
 #include "internal.h"
 #include "pnfs.h"
 #include "nfstrace.h"
+#include "fscache.h"
 
 #define NFSDBG_FACILITY		NFSDBG_PAGECACHE
 
@@ -68,6 +69,10 @@  void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
 	hdr->good_bytes = mirror->pg_count;
 	hdr->io_completion = desc->pg_io_completion;
 	hdr->dreq = desc->pg_dreq;
+	if (desc->pg_netfs) {
+		hdr->netfs = desc->pg_netfs;
+		nfs_netfs_get(desc->pg_netfs);
+	}
 	hdr->release = release;
 	hdr->completion_ops = desc->pg_completion_ops;
 	if (hdr->completion_ops->init_hdr)
@@ -846,6 +851,7 @@  void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 	desc->pg_lseg = NULL;
 	desc->pg_io_completion = NULL;
 	desc->pg_dreq = NULL;
+	desc->pg_netfs = NULL;
 	desc->pg_bsize = bsize;
 
 	desc->pg_mirror_count = 1;
@@ -896,6 +902,7 @@  int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 	struct nfs_page_array *pg_array = &hdr->page_array;
 	unsigned int pagecount, pageused;
 	gfp_t gfp_flags = nfs_io_gfp_mask();
+	struct nfs_netfs_io_data	*netfs = hdr->netfs;
 
 	pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 	pg_array->npages = pagecount;
@@ -940,6 +947,12 @@  int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 	/* Set up the argument struct */
 	nfs_pgio_rpcsetup(hdr, mirror->pg_count, desc->pg_ioflags, &cinfo);
 	desc->pg_rpc_callops = &nfs_pgio_common_ops;
+
+	/* Record netfs RPC count */
+	if (netfs) {
+		atomic_inc(&netfs->rpcs);
+		netfs->rpc_byte_count += hdr->args.count;
+	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
@@ -1360,6 +1373,7 @@  int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
 
 	desc->pg_io_completion = hdr->io_completion;
 	desc->pg_dreq = hdr->dreq;
+	desc->pg_netfs = hdr->netfs;
 	list_splice_init(&hdr->pages, &pages);
 	while (!list_empty(&pages)) {
 		struct nfs_page *req = nfs_list_entry(pages.next);
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 525e82ea9a9e..f7dcb72530ee 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -30,7 +30,7 @@ 
 
 #define NFSDBG_FACILITY		NFSDBG_PAGECACHE
 
-static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
+const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
 static const struct nfs_rw_ops nfs_rw_read_ops;
 
 static struct kmem_cache *nfs_rdata_cachep;
@@ -74,7 +74,7 @@  void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
 
-static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
+void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
 {
 	struct nfs_pgio_mirror *pgm;
 	unsigned long npages;
@@ -119,11 +119,7 @@  static void nfs_readpage_release(struct nfs_page *req, int error)
 
 	if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
 		SetPageError(page);
-	if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
-		if (PageUptodate(page))
-			nfs_fscache_write_page(inode, page);
-		unlock_page(page);
-	}
+
 	nfs_release_request(req);
 }
 
@@ -137,6 +133,8 @@  static void nfs_read_completion(struct nfs_pgio_header *hdr)
 {
 	unsigned long bytes = 0;
 	int error;
+	struct nfs_netfs_io_data	*netfs = hdr->netfs;
+	struct netfs_io_subrequest	*sreq = netfs->sreq;
 
 	if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 		goto out;
@@ -177,6 +175,24 @@  static void nfs_read_completion(struct nfs_pgio_header *hdr)
 		nfs_list_remove_request(req);
 		nfs_readpage_release(req, error);
 	}
+	if (netfs) {
+		if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
+			__set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
+
+		/* FIXME: What if multiple RPCs race, need locking (spinlock?) or is this ok? */
+		if (hdr->error)
+			netfs->error = hdr->error;
+		else
+			netfs->transferred += hdr->res.count;
+
+		/* Only the last RPC completion should call netfs_subreq_terminated() */
+		if (atomic_dec_and_test(&netfs->rpcs) &&
+		    (netfs->rpc_byte_count >= sreq->len)) { /* Could have EOF */
+			netfs_subreq_terminated(sreq, netfs->error ?: netfs->transferred, false);
+			nfs_netfs_put(netfs);
+			hdr->netfs = NULL;
+		}
+	}
 out:
 	hdr->release(hdr);
 }
@@ -202,7 +218,7 @@  nfs_async_read_error(struct list_head *head, int error)
 	}
 }
 
-static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
+const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 	.error_cleanup = nfs_async_read_error,
 	.completion = nfs_read_completion,
 };
@@ -294,12 +310,6 @@  nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
 
 	aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
 
-	if (!IS_SYNC(page->mapping->host)) {
-		error = nfs_fscache_read_page(page->mapping->host, page);
-		if (error == 0)
-			goto out_unlock;
-	}
-
 	new = nfs_create_request(ctx, page, 0, aligned_len);
 	if (IS_ERR(new))
 		goto out_error;
@@ -315,8 +325,6 @@  nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
 	return 0;
 out_error:
 	error = PTR_ERR(new);
-out_unlock:
-	unlock_page(page);
 out:
 	return error;
 }
@@ -330,8 +338,6 @@  nfs_pageio_add_page(struct nfs_pageio_descriptor *pgio,
 int nfs_read_folio(struct file *file, struct folio *folio)
 {
 	struct page *page = &folio->page;
-	struct nfs_pageio_descriptor pgio;
-	struct nfs_open_context *ctx;
 	struct inode *inode = page_file_mapping(page)->host;
 	int ret;
 
@@ -355,47 +361,19 @@  int nfs_read_folio(struct file *file, struct folio *folio)
 	if (NFS_STALE(inode))
 		goto out_unlock;
 
-	if (file == NULL) {
-		ret = -EBADF;
-		ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
-		if (ctx == NULL)
-			goto out_unlock;
-	} else
-		ctx = get_nfs_open_context(nfs_file_open_context(file));
-
-	xchg(&ctx->error, 0);
-	nfs_pageio_init_read(&pgio, inode, false,
-			     &nfs_async_read_completion_ops);
-
-	ret = nfs_pageio_add_page(&pgio, ctx, page);
-	if (ret)
-		goto out;
-
-	nfs_pageio_complete_read(&pgio);
-	ret = pgio.pg_error < 0 ? pgio.pg_error : 0;
-	if (!ret) {
-		ret = wait_on_page_locked_killable(page);
-		if (!PageUptodate(page) && !ret)
-			ret = xchg(&ctx->error, 0);
-	}
-out:
-	put_nfs_open_context(ctx);
-	trace_nfs_aop_readpage_done(inode, page, ret);
-	return ret;
+	ret = netfs_read_folio(file, folio);
+	goto out;
 out_unlock:
 	unlock_page(page);
+out:
 	trace_nfs_aop_readpage_done(inode, page, ret);
 	return ret;
 }
 
 void nfs_readahead(struct readahead_control *ractl)
 {
-	struct nfs_pageio_descriptor pgio;
-	struct nfs_open_context *ctx;
 	unsigned int nr_pages = readahead_count(ractl);
-	struct file *file = ractl->file;
 	struct inode *inode = ractl->mapping->host;
-	struct page *page;
 	int ret;
 
 	trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
@@ -405,27 +383,8 @@  void nfs_readahead(struct readahead_control *ractl)
 	if (NFS_STALE(inode))
 		goto out;
 
-	if (file == NULL) {
-		ret = -EBADF;
-		ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
-		if (ctx == NULL)
-			goto out;
-	} else
-		ctx = get_nfs_open_context(nfs_file_open_context(file));
-
-	nfs_pageio_init_read(&pgio, inode, false,
-			     &nfs_async_read_completion_ops);
-
-	while ((page = readahead_page(ractl)) != NULL) {
-		ret = nfs_pageio_add_page(&pgio, ctx, page);
-		put_page(page);
-		if (ret)
-			break;
-	}
-
-	nfs_pageio_complete_read(&pgio);
-
-	put_nfs_open_context(ctx);
+	ret = 0;
+	netfs_readahead(ractl);
 out:
 	trace_nfs_aop_readahead_done(inode, nr_pages, ret);
 }
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index ba7e2e4b0926..f942ed3f7215 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -101,6 +101,7 @@  struct nfs_pageio_descriptor {
 	struct pnfs_layout_segment *pg_lseg;
 	struct nfs_io_completion *pg_io_completion;
 	struct nfs_direct_req	*pg_dreq;
+	void			*pg_netfs;
 	unsigned int		pg_bsize;	/* default bsize for mirrors */
 
 	u32			pg_mirror_count;
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index e86cf6642d21..770c3348b696 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1619,6 +1619,7 @@  struct nfs_pgio_header {
 	const struct nfs_rw_ops	*rw_ops;
 	struct nfs_io_completion *io_completion;
 	struct nfs_direct_req	*dreq;
+	void			*netfs;
 
 	int			pnfs_error;
 	int			error;		/* merge with pnfs_error */