NFSv4.1: unify pnfs_pageio_init functions

Use common code for pnfs_pageio_init_{read,write} and use
a common generic pg_test function.

Note that this function always assumes the the layout driver's
pg_test method is implemented.

[Fix BUG]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>

fs/nfs/pagelist.c

@@ -229,6 +229,8 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 	desc->pg_ioflags = io_flags;
 	desc->pg_error = 0;
 	desc->pg_lseg = NULL;
+	desc->pg_test = NULL;
+	pnfs_pageio_init(desc, inode);
 }
 
 /**

fs/nfs/pnfs.c

@@ -1043,46 +1043,30 @@ pnfs_layout_process(struct nfs4_layoutget *lgp)
 	goto out;
 }
 
-static int pnfs_read_pg_test(struct nfs_pageio_descriptor *pgio,
-			     struct nfs_page *prev,
-			     struct nfs_page *req)
-{
-	if (pgio->pg_count == prev->wb_bytes) {
-		/* This is first coelesce call for a series of nfs_pages */
-		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
-						   prev->wb_context,
-						   req_offset(req),
-						   pgio->pg_count,
-						   IOMODE_READ,
-						   GFP_KERNEL);
-	} else if (pgio->pg_lseg &&
-		   req_offset(req) > end_offset(pgio->pg_lseg->pls_range.offset,
-						pgio->pg_lseg->pls_range.length))
-		return 0;
-	return NFS_SERVER(pgio->pg_inode)->pnfs_curr_ld->pg_test(pgio, prev, req);
-}
-
-void
-pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode)
+int
+pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
+		     struct nfs_page *req)
 {
-	struct pnfs_layoutdriver_type *ld;
+	enum pnfs_iomode access_type;
+	gfp_t gfp_flags;
 
-	ld = NFS_SERVER(inode)->pnfs_curr_ld;
-	pgio->pg_test = (ld && ld->pg_test) ? pnfs_read_pg_test : NULL;
-}
+	/* We assume that pg_ioflags == 0 iff we're reading a page */
+	if (pgio->pg_ioflags == 0) {
+		access_type = IOMODE_READ;
+		gfp_flags = GFP_KERNEL;
+	} else {
+		access_type = IOMODE_RW;
+		gfp_flags = GFP_NOFS;
+	}
 
-static int pnfs_write_pg_test(struct nfs_pageio_descriptor *pgio,
-			      struct nfs_page *prev,
-			      struct nfs_page *req)
-{
 	if (pgio->pg_count == prev->wb_bytes) {
 		/* This is first coelesce call for a series of nfs_pages */
 		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
 						   prev->wb_context,
 						   req_offset(req),
 						   pgio->pg_count,
-						   IOMODE_RW,
-						   GFP_NOFS);
+						   access_type,
+						   gfp_flags);
 	} else if (pgio->pg_lseg &&
 		   req_offset(req) > end_offset(pgio->pg_lseg->pls_range.offset,
 						pgio->pg_lseg->pls_range.length))
@@ -1090,15 +1074,6 @@ static int pnfs_write_pg_test(struct nfs_pageio_descriptor *pgio,
 	return NFS_SERVER(pgio->pg_inode)->pnfs_curr_ld->pg_test(pgio, prev, req);
 }
 
-void
-pnfs_pageio_init_write(struct nfs_pageio_descriptor *pgio, struct inode *inode)
-{
-	struct pnfs_layoutdriver_type *ld;
-
-	ld = NFS_SERVER(inode)->pnfs_curr_ld;
-	pgio->pg_test = (ld && ld->pg_test) ? pnfs_write_pg_test : NULL;
-}
-
 /*
  * Called by non rpc-based layout drivers
  */

fs/nfs/pnfs.h

@@ -158,8 +158,7 @@ enum pnfs_try_status pnfs_try_to_write_data(struct nfs_write_data *,
 					     const struct rpc_call_ops *, int);
 enum pnfs_try_status pnfs_try_to_read_data(struct nfs_read_data *,
 					    const struct rpc_call_ops *);
-void pnfs_pageio_init_read(struct nfs_pageio_descriptor *, struct inode *);
-void pnfs_pageio_init_write(struct nfs_pageio_descriptor *, struct inode *);
+int pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev, struct nfs_page *req);
 int pnfs_layout_process(struct nfs4_layoutget *lgp);
 void pnfs_free_lseg_list(struct list_head *tmp_list);
 void pnfs_destroy_layout(struct nfs_inode *);
@@ -293,6 +292,13 @@ static inline int pnfs_return_layout(struct inode *ino)
 	return 0;
 }
 
+static inline void pnfs_pageio_init(struct nfs_pageio_descriptor *pgio,
+				    struct inode *inode)
+{
+	if (NFS_SERVER(inode)->pnfs_curr_ld)
+		pgio->pg_test = pnfs_generic_pg_test;
+}
+
 #else  /* CONFIG_NFS_V4_1 */
 
 static inline void pnfs_destroy_all_layouts(struct nfs_client *clp)
@@ -376,16 +382,9 @@ static inline void unset_pnfs_layoutdriver(struct nfs_server *s)
 {
 }
 
-static inline void
-pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *ino)
-{
-	pgio->pg_test = NULL;
-}
-
-static inline void
-pnfs_pageio_init_write(struct nfs_pageio_descriptor *pgio, struct inode *ino)
+static inline void pnfs_pageio_init(struct nfs_pageio_descriptor *pgio,
+				    struct inode *inode)
 {
-	pgio->pg_test = NULL;
 }
 
 static inline void

fs/nfs/read.c

@@ -664,7 +664,6 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
 	if (ret == 0)
 		goto read_complete; /* all pages were read */
 
-	pnfs_pageio_init_read(&pgio, inode);
 	if (rsize < PAGE_CACHE_SIZE)
 		nfs_pageio_init(&pgio, inode, nfs_pagein_multi, rsize, 0);
 	else

fs/nfs/write.c

@@ -1036,8 +1036,6 @@ static void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
 {
 	size_t wsize = NFS_SERVER(inode)->wsize;
 
-	pnfs_pageio_init_write(pgio, inode);
-
 	if (wsize < PAGE_CACHE_SIZE)
 		nfs_pageio_init(pgio, inode, nfs_flush_multi, wsize, ioflags);
 	else