lightnvm: make ppa_list const in nvm_set_rqd_list

The passed by reference ppa list in nvm_set_rqd_list() is updated when
multiple planes are available. In that case, each PPA plane is
incremented when the device side PPA list is created. This prevents the
caller to rely on the PPA list to be unmodified after a call.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/lightnvm/core.c

@@ -237,9 +237,10 @@ void nvm_generic_to_addr_mode(struct nvm_dev *dev, struct nvm_rq *rqd)
 EXPORT_SYMBOL(nvm_generic_to_addr_mode);
 
 int nvm_set_rqd_ppalist(struct nvm_dev *dev, struct nvm_rq *rqd,
-				struct ppa_addr *ppas, int nr_ppas, int vblk)
+			const struct ppa_addr *ppas, int nr_ppas, int vblk)
 {
 	int i, plane_cnt, pl_idx;
+	struct ppa_addr ppa;
 
 	if ((!vblk || dev->plane_mode == NVM_PLANE_SINGLE) && nr_ppas == 1) {
 		rqd->nr_ppas = nr_ppas;
@@ -264,8 +265,9 @@ int nvm_set_rqd_ppalist(struct nvm_dev *dev, struct nvm_rq *rqd,
 
 		for (i = 0; i < nr_ppas; i++) {
 			for (pl_idx = 0; pl_idx < plane_cnt; pl_idx++) {
-				ppas[i].g.pl = pl_idx;
-				rqd->ppa_list[(pl_idx * nr_ppas) + i] = ppas[i];
+				ppa = ppas[i];
+				ppa.g.pl = pl_idx;
+				rqd->ppa_list[(pl_idx * nr_ppas) + i] = ppa;
 			}
 		}
 	}

include/linux/lightnvm.h

@@ -534,7 +534,7 @@ extern int nvm_submit_io(struct nvm_dev *, struct nvm_rq *);
 extern void nvm_generic_to_addr_mode(struct nvm_dev *, struct nvm_rq *);
 extern void nvm_addr_to_generic_mode(struct nvm_dev *, struct nvm_rq *);
 extern int nvm_set_rqd_ppalist(struct nvm_dev *, struct nvm_rq *,
-						struct ppa_addr *, int, int);
+					const struct ppa_addr *, int, int);
 extern void nvm_free_rqd_ppalist(struct nvm_dev *, struct nvm_rq *);
 extern int nvm_erase_ppa(struct nvm_dev *, struct ppa_addr *, int);
 extern int nvm_erase_blk(struct nvm_dev *, struct nvm_block *);