NFS: rewrite directio read to use async coalesce code

This also has the advantage that it allows directio to use pnfs.
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/internal.h

@@ -304,8 +304,9 @@ struct nfs_pgio_completion_ops;
 /* read.c */
 extern struct nfs_read_header *nfs_readhdr_alloc(void);
 extern void nfs_readhdr_free(struct nfs_pgio_header *hdr);
-extern struct nfs_read_data *nfs_readdata_alloc(struct nfs_pgio_header *hdr,
-						unsigned int pagecount);
+extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
+			struct inode *inode,
+			const struct nfs_pgio_completion_ops *compl_ops);
 extern int nfs_initiate_read(struct rpc_clnt *clnt,
 			     struct nfs_read_data *data,
 			     const struct rpc_call_ops *call_ops);

fs/nfs/pagelist.c

@@ -48,8 +48,11 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
 	hdr->cred = hdr->req->wb_context->cred;
 	hdr->io_start = req_offset(hdr->req);
 	hdr->good_bytes = desc->pg_count;
+	hdr->dreq = desc->pg_dreq;
 	hdr->release = release;
 	hdr->completion_ops = desc->pg_completion_ops;
+	if (hdr->completion_ops->init_hdr)
+		hdr->completion_ops->init_hdr(hdr);
 }
 
 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
@@ -116,9 +119,6 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
 	req->wb_page    = page;
 	req->wb_index	= page->index;
 	page_cache_get(page);
-	BUG_ON(PagePrivate(page));
-	BUG_ON(!PageLocked(page));
-	BUG_ON(page->mapping->host != inode);
 	req->wb_offset  = offset;
 	req->wb_pgbase	= offset;
 	req->wb_bytes   = count;
@@ -257,6 +257,7 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 	desc->pg_ioflags = io_flags;
 	desc->pg_error = 0;
 	desc->pg_lseg = NULL;
+	desc->pg_dreq = NULL;
 }
 
 /**

fs/nfs/read.c

@@ -51,8 +51,8 @@ struct nfs_read_header *nfs_readhdr_alloc()
 	return rhdr;
 }
 
-struct nfs_read_data *nfs_readdata_alloc(struct nfs_pgio_header *hdr,
-					 unsigned int pagecount)
+static struct nfs_read_data *nfs_readdata_alloc(struct nfs_pgio_header *hdr,
+						unsigned int pagecount)
 {
 	struct nfs_read_data *data, *prealloc;
 
@@ -123,9 +123,9 @@ void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
 
-static void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
-				struct inode *inode,
-				const struct nfs_pgio_completion_ops *compl_ops)
+void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
+			  struct inode *inode,
+			  const struct nfs_pgio_completion_ops *compl_ops)
 {
 	if (!pnfs_pageio_init_read(pgio, inode, compl_ops))
 		nfs_pageio_init_read_mds(pgio, inode, compl_ops);

include/linux/nfs_page.h

@@ -68,6 +68,7 @@ struct nfs_pageio_descriptor {
 	const struct rpc_call_ops *pg_rpc_callops;
 	const struct nfs_pgio_completion_ops *pg_completion_ops;
 	struct pnfs_layout_segment *pg_lseg;
+	struct nfs_direct_req	*pg_dreq;
 };
 
 #define NFS_WBACK_BUSY(req)	(test_bit(PG_BUSY,&(req)->wb_flags))

include/linux/nfs_xdr.h

@@ -1208,6 +1208,7 @@ struct nfs_pgio_header {
 	const struct rpc_call_ops *mds_ops;
 	void (*release) (struct nfs_pgio_header *hdr);
 	const struct nfs_pgio_completion_ops *completion_ops;
+	struct nfs_direct_req	*dreq;
 	spinlock_t		lock;
 	/* fields protected by lock */
 	int			pnfs_error;
@@ -1221,8 +1222,6 @@ struct nfs_read_header {
 	struct nfs_read_data	rpc_data;
 };
 
-struct nfs_direct_req;
-
 struct nfs_write_data {
 	struct nfs_pgio_header	*header;
 	struct list_head	list;
@@ -1264,6 +1263,7 @@ struct nfs_commit_data {
 
 struct nfs_pgio_completion_ops {
 	void	(*error_cleanup)(struct list_head *head);
+	void	(*init_hdr)(struct nfs_pgio_header *hdr);
 	void	(*completion)(struct nfs_pgio_header *hdr);
 };