NFSv4.1: Add an initialisation callback for pNFS

Ensure that we always get a layout before setting up the i/o request.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4filelayout.c

@@ -682,11 +682,13 @@ filelayout_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 }
 
 static const struct nfs_pageio_ops filelayout_pg_read_ops = {
+	.pg_init = pnfs_generic_pg_init_read,
 	.pg_test = filelayout_pg_test,
 	.pg_doio = nfs_generic_pg_readpages,
 };
 
 static const struct nfs_pageio_ops filelayout_pg_write_ops = {
+	.pg_init = pnfs_generic_pg_init_write,
 	.pg_test = filelayout_pg_test,
 	.pg_doio = nfs_generic_pg_writepages,
 };

fs/nfs/objlayout/objio_osd.c

@@ -1008,11 +1008,13 @@ static bool objio_pg_test(struct nfs_pageio_descriptor *pgio,
 }
 
 static const struct nfs_pageio_ops objio_pg_read_ops = {
+	.pg_init = pnfs_generic_pg_init_read,
 	.pg_test = objio_pg_test,
 	.pg_doio = nfs_generic_pg_readpages,
 };
 
 static const struct nfs_pageio_ops objio_pg_write_ops = {
+	.pg_init = pnfs_generic_pg_init_write,
 	.pg_test = objio_pg_test,
 	.pg_doio = nfs_generic_pg_writepages,
 };

fs/nfs/pagelist.c

@@ -295,6 +295,8 @@ static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 		if (!nfs_can_coalesce_requests(prev, req, desc))
 			return 0;
 	} else {
+		if (desc->pg_ops->pg_init)
+			desc->pg_ops->pg_init(desc, req);
 		desc->pg_base = req->wb_pgbase;
 	}
 	nfs_list_remove_request(req);

fs/nfs/pnfs.c

@@ -911,7 +911,7 @@ pnfs_find_lseg(struct pnfs_layout_hdr *lo,
  * Layout segment is retreived from the server if not cached.
  * The appropriate layout segment is referenced and returned to the caller.
  */
-struct pnfs_layout_segment *
+static struct pnfs_layout_segment *
 pnfs_update_layout(struct inode *ino,
 		   struct nfs_open_context *ctx,
 		   loff_t pos,
@@ -1055,6 +1055,34 @@ pnfs_layout_process(struct nfs4_layoutget *lgp)
 	goto out;
 }
 
+void
+pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
+{
+	BUG_ON(pgio->pg_lseg != NULL);
+
+	pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+					   req->wb_context,
+					   req_offset(req),
+					   req->wb_bytes,
+					   IOMODE_READ,
+					   GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_read);
+
+void
+pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
+{
+	BUG_ON(pgio->pg_lseg != NULL);
+
+	pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+					   req->wb_context,
+					   req_offset(req),
+					   req->wb_bytes,
+					   IOMODE_RW,
+					   GFP_NOFS);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_write);
+
 bool
 pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode)
 {
@@ -1083,31 +1111,8 @@ bool
 pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 		     struct nfs_page *req)
 {
-	enum pnfs_iomode access_type;
-	gfp_t gfp_flags;
-
-	/* 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;
-	}
-
-	if (pgio->pg_lseg == NULL) {
-		if (pgio->pg_count != prev->wb_bytes)
-			return true;
-		/* 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(prev),
-						   pgio->pg_count,
-						   access_type,
-						   gfp_flags);
 	if (pgio->pg_lseg == NULL)
-			return true;
-	}
+		return nfs_generic_pg_test(pgio, prev, req);
 
 	/*
 	 * Test if a nfs_page is fully contained in the pnfs_layout_range.

fs/nfs/pnfs.h

@@ -149,10 +149,6 @@ extern int nfs4_proc_layoutreturn(struct nfs4_layoutreturn *lrp);
 /* pnfs.c */
 void get_layout_hdr(struct pnfs_layout_hdr *lo);
 void put_lseg(struct pnfs_layout_segment *lseg);
-struct pnfs_layout_segment *
-pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
-		   loff_t pos, u64 count, enum pnfs_iomode access_type,
-		   gfp_t gfp_flags);
 
 bool pnfs_pageio_init_read(struct nfs_pageio_descriptor *, struct inode *);
 bool pnfs_pageio_init_write(struct nfs_pageio_descriptor *, struct inode *, int);
@@ -163,6 +159,8 @@ 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_generic_pg_init_read(struct nfs_pageio_descriptor *, struct nfs_page *);
+void pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *, struct nfs_page *);
 bool 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);
@@ -318,14 +316,6 @@ static inline void put_lseg(struct pnfs_layout_segment *lseg)
 {
 }
 
-static inline struct pnfs_layout_segment *
-pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
-		   loff_t pos, u64 count, enum pnfs_iomode access_type,
-		   gfp_t gfp_flags)
-{
-	return NULL;
-}
-
 static inline enum pnfs_try_status
 pnfs_try_to_read_data(struct nfs_read_data *data,
 		      const struct rpc_call_ops *call_ops)

fs/nfs/read.c

@@ -147,9 +147,7 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
 		zero_user_segment(page, len, PAGE_CACHE_SIZE);
 
 	nfs_pageio_init_read(&pgio, inode);
-	nfs_list_add_request(new, &pgio.pg_list);
-	pgio.pg_count = len;
-
+	nfs_pageio_add_request(&pgio, new);
 	nfs_pageio_complete(&pgio);
 	return 0;
 }
@@ -281,7 +279,7 @@ static int nfs_pagein_multi(struct nfs_pageio_descriptor *desc)
 	unsigned int offset;
 	int requests = 0;
 	int ret = 0;
-	struct pnfs_layout_segment *lseg;
+	struct pnfs_layout_segment *lseg = desc->pg_lseg;
 	LIST_HEAD(list);
 
 	nfs_list_remove_request(req);
@@ -299,10 +297,6 @@ static int nfs_pagein_multi(struct nfs_pageio_descriptor *desc)
 	} while(nbytes != 0);
 	atomic_set(&req->wb_complete, requests);
 
-	BUG_ON(desc->pg_lseg != NULL);
-	lseg = pnfs_update_layout(desc->pg_inode, req->wb_context,
-				  req_offset(req), desc->pg_count,
-				  IOMODE_READ, GFP_KERNEL);
 	ClearPageError(page);
 	offset = 0;
 	nbytes = desc->pg_count;
@@ -336,6 +330,8 @@ static int nfs_pagein_multi(struct nfs_pageio_descriptor *desc)
 	}
 	SetPageError(page);
 	nfs_readpage_release(req);
+	put_lseg(lseg);
+	desc->pg_lseg = NULL;
 	return -ENOMEM;
 }
 
@@ -364,10 +360,6 @@ static int nfs_pagein_one(struct nfs_pageio_descriptor *desc)
 		*pages++ = req->wb_page;
 	}
 	req = nfs_list_entry(data->pages.next);
-	if ((!lseg) && list_is_singular(&data->pages))
-		lseg = pnfs_update_layout(desc->pg_inode, req->wb_context,
-					  req_offset(req), desc->pg_count,
-					  IOMODE_READ, GFP_KERNEL);
 
 	ret = nfs_read_rpcsetup(req, data, &nfs_read_full_ops, desc->pg_count,
 				0, lseg);

fs/nfs/write.c

@@ -916,7 +916,7 @@ static int nfs_flush_multi(struct nfs_pageio_descriptor *desc)
 	unsigned int offset;
 	int requests = 0;
 	int ret = 0;
-	struct pnfs_layout_segment *lseg;
+	struct pnfs_layout_segment *lseg = desc->pg_lseg;
 	LIST_HEAD(list);
 
 	nfs_list_remove_request(req);
@@ -940,10 +940,6 @@ static int nfs_flush_multi(struct nfs_pageio_descriptor *desc)
 	} while (nbytes != 0);
 	atomic_set(&req->wb_complete, requests);
 
-	BUG_ON(desc->pg_lseg);
-	lseg = pnfs_update_layout(desc->pg_inode, req->wb_context,
-				  req_offset(req), desc->pg_count,
-				  IOMODE_RW, GFP_NOFS);
 	ClearPageError(page);
 	offset = 0;
 	nbytes = desc->pg_count;
@@ -976,6 +972,8 @@ static int nfs_flush_multi(struct nfs_pageio_descriptor *desc)
 		nfs_writedata_free(data);
 	}
 	nfs_redirty_request(req);
+	put_lseg(lseg);
+	desc->pg_lseg = NULL;
 	return -ENOMEM;
 }
 
@@ -1016,10 +1014,6 @@ static int nfs_flush_one(struct nfs_pageio_descriptor *desc)
 		*pages++ = req->wb_page;
 	}
 	req = nfs_list_entry(data->pages.next);
-	if ((!lseg) && list_is_singular(&data->pages))
-		lseg = pnfs_update_layout(desc->pg_inode, req->wb_context,
-					  req_offset(req), desc->pg_count,
-					  IOMODE_RW, GFP_NOFS);
 
 	if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 	    (desc->pg_moreio || NFS_I(desc->pg_inode)->ncommit))

include/linux/nfs_page.h

@@ -57,6 +57,7 @@ struct nfs_page {
 
 struct nfs_pageio_descriptor;
 struct nfs_pageio_ops {
+	void	(*pg_init)(struct nfs_pageio_descriptor *, struct nfs_page *);
 	bool	(*pg_test)(struct nfs_pageio_descriptor *, struct nfs_page *, struct nfs_page *);
 	int	(*pg_doio)(struct nfs_pageio_descriptor *);
 };