lightnvm: pblk: gracefully handle GC vmalloc fail

Currently when we fail on rq data allocation in gc, it skips moving
active data and moves line straigt to its free state. Losing user
data in the process.

Move the data allocation to an earlier phase of GC, where we can still
fail gracefully by moving line back to the closed state.
Signed-off-by: Igor Konopko <igor.j.konopko@intel.com>
Reviewed-by: Javier González <javier@javigon.com>
Reviewed-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/lightnvm/pblk-gc.c

@@ -84,8 +84,6 @@ static void pblk_gc_line_ws(struct work_struct *work)
 	struct pblk_line_ws *gc_rq_ws = container_of(work,
 						struct pblk_line_ws, ws);
 	struct pblk *pblk = gc_rq_ws->pblk;
-	struct nvm_tgt_dev *dev = pblk->dev;
-	struct nvm_geo *geo = &dev->geo;
 	struct pblk_gc *gc = &pblk->gc;
 	struct pblk_line *line = gc_rq_ws->line;
 	struct pblk_gc_rq *gc_rq = gc_rq_ws->priv;
@@ -93,13 +91,6 @@ static void pblk_gc_line_ws(struct work_struct *work)
 
 	up(&gc->gc_sem);
 
-	gc_rq->data = vmalloc(array_size(gc_rq->nr_secs, geo->csecs));
-	if (!gc_rq->data) {
-		pblk_err(pblk, "could not GC line:%d (%d/%d)\n",
-					line->id, *line->vsc, gc_rq->nr_secs);
-		goto out;
-	}
-
 	/* Read from GC victim block */
 	ret = pblk_submit_read_gc(pblk, gc_rq);
 	if (ret) {
@@ -189,6 +180,8 @@ static void pblk_gc_line_prepare_ws(struct work_struct *work)
 	struct pblk_line *line = line_ws->line;
 	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 	struct pblk_line_meta *lm = &pblk->lm;
+	struct nvm_tgt_dev *dev = pblk->dev;
+	struct nvm_geo *geo = &dev->geo;
 	struct pblk_gc *gc = &pblk->gc;
 	struct pblk_line_ws *gc_rq_ws;
 	struct pblk_gc_rq *gc_rq;
@@ -247,9 +240,13 @@ static void pblk_gc_line_prepare_ws(struct work_struct *work)
 	gc_rq->nr_secs = nr_secs;
 	gc_rq->line = line;
 
+	gc_rq->data = vmalloc(array_size(gc_rq->nr_secs, geo->csecs));
+	if (!gc_rq->data)
+		goto fail_free_gc_rq;
+
 	gc_rq_ws = kmalloc(sizeof(struct pblk_line_ws), GFP_KERNEL);
 	if (!gc_rq_ws)
-		goto fail_free_gc_rq;
+		goto fail_free_gc_data;
 
 	gc_rq_ws->pblk = pblk;
 	gc_rq_ws->line = line;
@@ -281,6 +278,8 @@ static void pblk_gc_line_prepare_ws(struct work_struct *work)
 
 	return;
 
+fail_free_gc_data:
+	vfree(gc_rq->data);
 fail_free_gc_rq:
 	kfree(gc_rq);
 fail_free_lba_list: