nfs: remove ->read_pageio_init from rpc ops

The read_pageio_init method is just a very convoluted way to grab the
right nfs_pageio_ops vector.  The vector to chose is not a choice of
protocol version, but just a pNFS vs MDS I/O choice that can simply be
done inside nfs_pageio_init_read based on the presence of a layout
driver, and a new force_mds flag to the special case of falling back
to MDS I/O on a pNFS-capable volume.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/direct.c

@@ -424,7 +424,7 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
 	size_t requested_bytes = 0;
 	unsigned long seg;
 
-	NFS_PROTO(dreq->inode)->read_pageio_init(&desc, dreq->inode,
+	nfs_pageio_init_read(&desc, dreq->inode, false,
 			     &nfs_direct_read_completion_ops);
 	get_dreq(dreq);
 	desc.pg_dreq = dreq;

fs/nfs/internal.h

@@ -398,7 +398,7 @@ struct nfs_pgio_completion_ops;
 extern struct nfs_read_header *nfs_readhdr_alloc(void);
 extern void nfs_readhdr_free(struct nfs_pgio_header *hdr);
 extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
-			struct inode *inode,
+			struct inode *inode, bool force_mds,
 			const struct nfs_pgio_completion_ops *compl_ops);
 extern int nfs_initiate_read(struct rpc_clnt *clnt,
 			     struct nfs_read_data *data,

fs/nfs/nfs3proc.c

@@ -947,7 +947,6 @@ const struct nfs_rpc_ops nfs_v3_clientops = {
 	.pathconf	= nfs3_proc_pathconf,
 	.decode_dirent	= nfs3_decode_dirent,
 	.read_setup	= nfs3_proc_read_setup,
-	.read_pageio_init = nfs_pageio_init_read,
 	.read_rpc_prepare = nfs3_proc_read_rpc_prepare,
 	.read_done	= nfs3_read_done,
 	.write_setup	= nfs3_proc_write_setup,

fs/nfs/nfs4proc.c

@@ -8433,7 +8433,6 @@ const struct nfs_rpc_ops nfs_v4_clientops = {
 	.set_capabilities = nfs4_server_capabilities,
 	.decode_dirent	= nfs4_decode_dirent,
 	.read_setup	= nfs4_proc_read_setup,
-	.read_pageio_init = pnfs_pageio_init_read,
 	.read_rpc_prepare = nfs4_proc_read_rpc_prepare,
 	.read_done	= nfs4_read_done,
 	.write_setup	= nfs4_proc_write_setup,

fs/nfs/pnfs.c

@@ -1434,19 +1434,6 @@ pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio,
 }
 EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_write);
 
-void
-pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode,
-		      const struct nfs_pgio_completion_ops *compl_ops)
-{
-	struct nfs_server *server = NFS_SERVER(inode);
-	struct pnfs_layoutdriver_type *ld = server->pnfs_curr_ld;
-
-	if (ld == NULL)
-		nfs_pageio_init_read(pgio, inode, compl_ops);
-	else
-		nfs_pageio_init(pgio, inode, ld->pg_read_ops, compl_ops, server->rsize, 0);
-}
-
 bool
 pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 		     struct nfs_page *req)
@@ -1641,7 +1628,7 @@ int pnfs_read_done_resend_to_mds(struct inode *inode,
 	LIST_HEAD(failed);
 
 	/* Resend all requests through the MDS */
-	nfs_pageio_init_read(&pgio, inode, compl_ops);
+	nfs_pageio_init_read(&pgio, inode, true, compl_ops);
 	pgio.pg_dreq = dreq;
 	while (!list_empty(head)) {
 		struct nfs_page *req = nfs_list_entry(head->next);

fs/nfs/pnfs.h

@@ -180,9 +180,6 @@ extern int nfs4_proc_layoutreturn(struct nfs4_layoutreturn *lrp);
 void pnfs_get_layout_hdr(struct pnfs_layout_hdr *lo);
 void pnfs_put_lseg(struct pnfs_layout_segment *lseg);
 
-void pnfs_pageio_init_read(struct nfs_pageio_descriptor *, struct inode *,
-			   const struct nfs_pgio_completion_ops *);
-
 void set_pnfs_layoutdriver(struct nfs_server *, const struct nfs_fh *, u32);
 void unset_pnfs_layoutdriver(struct nfs_server *);
 void pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *, struct nfs_page *);
@@ -459,12 +456,6 @@ static inline void unset_pnfs_layoutdriver(struct nfs_server *s)
 {
 }
 
-static inline void pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode,
-					 const struct nfs_pgio_completion_ops *compl_ops)
-{
-	nfs_pageio_init_read(pgio, inode, compl_ops);
-}
-
 static inline int
 pnfs_commit_list(struct inode *inode, struct list_head *mds_pages, int how,
 		 struct nfs_commit_info *cinfo)

fs/nfs/proc.c

@@ -735,7 +735,6 @@ const struct nfs_rpc_ops nfs_v2_clientops = {
 	.pathconf	= nfs_proc_pathconf,
 	.decode_dirent	= nfs2_decode_dirent,
 	.read_setup	= nfs_proc_read_setup,
-	.read_pageio_init = nfs_pageio_init_read,
 	.read_rpc_prepare = nfs_proc_read_rpc_prepare,
 	.read_done	= nfs_read_done,
 	.write_setup	= nfs_proc_write_setup,

fs/nfs/read.c

@@ -24,6 +24,7 @@
 #include "internal.h"
 #include "iostat.h"
 #include "fscache.h"
+#include "pnfs.h"
 
 #define NFSDBG_FACILITY		NFSDBG_PAGECACHE
 
@@ -114,11 +115,17 @@ int nfs_return_empty_page(struct page *page)
 }
 
 void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
-			      struct inode *inode,
+			      struct inode *inode, bool force_mds,
 			      const struct nfs_pgio_completion_ops *compl_ops)
 {
-	nfs_pageio_init(pgio, inode, &nfs_pageio_read_ops, compl_ops,
-			NFS_SERVER(inode)->rsize, 0);
+	struct nfs_server *server = NFS_SERVER(inode);
+	const struct nfs_pageio_ops *pg_ops = &nfs_pageio_read_ops;
+
+#ifdef CONFIG_NFS_V4_1
+	if (server->pnfs_curr_ld && !force_mds)
+		pg_ops = server->pnfs_curr_ld->pg_read_ops;
+#endif
+	nfs_pageio_init(pgio, inode, pg_ops, compl_ops, server->rsize, 0);
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
 
@@ -147,7 +154,8 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
 	if (len < PAGE_CACHE_SIZE)
 		zero_user_segment(page, len, PAGE_CACHE_SIZE);
 
-	NFS_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops);
+	nfs_pageio_init_read(&pgio, inode, false,
+			     &nfs_async_read_completion_ops);
 	nfs_pageio_add_request(&pgio, new);
 	nfs_pageio_complete(&pgio);
 	NFS_I(inode)->read_io += pgio.pg_bytes_written;
@@ -654,7 +662,8 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
 	if (ret == 0)
 		goto read_complete; /* all pages were read */
 
-	NFS_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops);
+	nfs_pageio_init_read(&pgio, inode, false,
+			     &nfs_async_read_completion_ops);
 
 	ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
 

include/linux/nfs_xdr.h

@@ -1466,8 +1466,6 @@ struct nfs_rpc_ops {
 	int	(*set_capabilities)(struct nfs_server *, struct nfs_fh *);
 	int	(*decode_dirent)(struct xdr_stream *, struct nfs_entry *, int);
 	void	(*read_setup)   (struct nfs_read_data *, struct rpc_message *);
-	void	(*read_pageio_init)(struct nfs_pageio_descriptor *, struct inode *,
-				    const struct nfs_pgio_completion_ops *);
 	int	(*read_rpc_prepare)(struct rpc_task *, struct nfs_read_data *);
 	int	(*read_done)  (struct rpc_task *, struct nfs_read_data *);
 	void	(*write_setup)  (struct nfs_write_data *, struct rpc_message *);