UBI: fix error handling in erase worker

Do not switch to read-only mode in case of -EINTR and some
other obvious cases. Switch to RO mode only when we do not
know what is the error.
Reported-by: Vinit Agnihotri <vinit.agnihotri@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/wl.c

@@ -1060,9 +1060,8 @@ static int ensure_wear_leveling(struct ubi_device *ubi)
 static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
 			int cancel)
 {
-	int err;
 	struct ubi_wl_entry *e = wl_wrk->e;
-	int pnum = e->pnum;
+	int pnum = e->pnum, err, need;
 
 	if (cancel) {
 		dbg_wl("cancel erasure of PEB %d EC %d", pnum, e->ec);
@@ -1097,24 +1096,32 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
 	kfree(wl_wrk);
 	kmem_cache_free(wl_entries_slab, e);
 
-	if (err != -EIO) {
+	if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
+	    err == -EBUSY) {
+		int err1;
+
+		/* Re-schedule the LEB for erasure */
+		err1 = schedule_erase(ubi, e, 0);
+		if (err1) {
+			err = err1;
+			goto out_ro;
+		}
+		return err;
+	} else if (err != -EIO) {
 		/*
 		 * If this is not %-EIO, we have no idea what to do. Scheduling
 		 * this physical eraseblock for erasure again would cause
 		 * errors again and again. Well, lets switch to RO mode.
 		 */
-		ubi_ro_mode(ubi);
-		return err;
+		goto out_ro;
 	}
 
 	/* It is %-EIO, the PEB went bad */
 
 	if (!ubi->bad_allowed) {
 		ubi_err("bad physical eraseblock %d detected", pnum);
-		ubi_ro_mode(ubi);
-		err = -EIO;
-	} else {
-		int need;
+		goto out_ro;
+	}
 
 	spin_lock(&ubi->volumes_lock);
 	need = ubi->beb_rsvd_level - ubi->beb_rsvd_pebs + 1;
@@ -1130,18 +1137,15 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
 	if (ubi->beb_rsvd_pebs == 0) {
 		spin_unlock(&ubi->volumes_lock);
 		ubi_err("no reserved physical eraseblocks");
-			ubi_ro_mode(ubi);
-			return -EIO;
+		goto out_ro;
 	}
 
 	spin_unlock(&ubi->volumes_lock);
 	ubi_msg("mark PEB %d as bad", pnum);
 
 	err = ubi_io_mark_bad(ubi, pnum);
-		if (err) {
-			ubi_ro_mode(ubi);
-			return err;
-		}
+	if (err)
+		goto out_ro;
 
 	spin_lock(&ubi->volumes_lock);
 	ubi->beb_rsvd_pebs -= 1;
@@ -1151,9 +1155,12 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
 	if (ubi->beb_rsvd_pebs == 0)
 		ubi_warn("last PEB from the reserved pool was used");
 	spin_unlock(&ubi->volumes_lock);
-	}
 
 	return err;
+
+out_ro:
+	ubi_ro_mode(ubi);
+	return err;
 }
 
 /**