pNFS/flexfiles: Check the layout segment range before doing I/O

When starting to read or write with a layout segment, check that the
range matches our request.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -830,6 +830,14 @@ ff_layout_pg_get_read(struct nfs_pageio_descriptor *pgio,
 	}
 }
 
+static void
+ff_layout_pg_check_layout(struct nfs_pageio_descriptor *pgio,
+			  struct nfs_page *req)
+{
+	pnfs_generic_pg_check_layout(pgio);
+	pnfs_generic_pg_check_range(pgio, req);
+}
+
 static void
 ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio,
 			struct nfs_page *req)
@@ -840,7 +848,7 @@ ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio,
 	int ds_idx;
 
 retry:
-	pnfs_generic_pg_check_layout(pgio);
+	ff_layout_pg_check_layout(pgio, req);
 	/* Use full layout for now */
 	if (!pgio->pg_lseg) {
 		ff_layout_pg_get_read(pgio, req, false);
@@ -900,7 +908,7 @@ ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
 	int i;
 
 retry:
-	pnfs_generic_pg_check_layout(pgio);
+	ff_layout_pg_check_layout(pgio, req);
 	if (!pgio->pg_lseg) {
 		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
 						   nfs_req_openctx(req),

fs/nfs/pnfs.c

@@ -2611,7 +2611,7 @@ EXPORT_SYMBOL_GPL(pnfs_generic_pg_check_layout);
  * Check for any intersection between the request and the pgio->pg_lseg,
  * and if none, put this pgio->pg_lseg away.
  */
-static void
+void
 pnfs_generic_pg_check_range(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
 {
 	if (pgio->pg_lseg && !pnfs_lseg_request_intersecting(pgio->pg_lseg, req)) {
@@ -2619,6 +2619,7 @@ pnfs_generic_pg_check_range(struct nfs_pageio_descriptor *pgio, struct nfs_page
 		pgio->pg_lseg = NULL;
 	}
 }
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_check_range);
 
 void
 pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)

fs/nfs/pnfs.h

@@ -252,6 +252,7 @@ void pnfs_put_lseg(struct pnfs_layout_segment *lseg);
 void set_pnfs_layoutdriver(struct nfs_server *, const struct nfs_fh *, struct nfs_fsinfo *);
 void unset_pnfs_layoutdriver(struct nfs_server *);
 void pnfs_generic_pg_check_layout(struct nfs_pageio_descriptor *pgio);
+void pnfs_generic_pg_check_range(struct nfs_pageio_descriptor *pgio, struct nfs_page *req);
 void pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *, struct nfs_page *);
 int pnfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc);
 void pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio,