ubi: Fix races around ubi_refill_pools()

When writing a new Fastmap the first thing that happens
is refilling the pools in memory.
At this stage it is possible that new PEBs from the new pools
get already claimed and written with data.
If this happens before the new Fastmap data structure hits the
flash and we face power cut the freshly written PEB will not
scanned and unnoticed.

Solve the issue by locking the pools until Fastmap is written.

Cc: <stable@vger.kernel.org>
Fixes: dbb7d2a88d ("UBI: Add fastmap core")
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 14 insertions, 6 deletions

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 19206ad677b2..b5b8cd6f481c 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -580,7 +580,7 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
  * failure.
  */
 static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
-			  int vol_id, int lnum, int torture)
+			  int vol_id, int lnum, int torture, bool nested)
 {
 	struct ubi_work *wl_wrk;
 
@@ -599,7 +599,10 @@ static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
 	wl_wrk->lnum = lnum;
 	wl_wrk->torture = torture;
 
-	schedule_ubi_work(ubi, wl_wrk);
+	if (nested)
+		__schedule_ubi_work(ubi, wl_wrk);
+	else
+		schedule_ubi_work(ubi, wl_wrk);
 	return 0;
 }
 
@@ -663,6 +666,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 
 	vid_hdr = ubi_get_vid_hdr(vidb);
 
+	down_read(&ubi->fm_eba_sem);
 	mutex_lock(&ubi->move_mutex);
 	spin_lock(&ubi->wl_lock);
 	ubi_assert(!ubi->move_from && !ubi->move_to);
@@ -893,6 +897,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 
 	dbg_wl("done");
 	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
 	return 0;
 
 	/*
@@ -943,6 +948,7 @@ out_not_moved:
 	}
 
 	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
 	return 0;
 
 out_error:
@@ -964,6 +970,7 @@ out_error:
 out_ro:
 	ubi_ro_mode(ubi);
 	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
 	ubi_assert(err != 0);
 	return err < 0 ? err : -EIO;
 
@@ -971,6 +978,7 @@ out_cancel:
 	ubi->wl_scheduled = 0;
 	spin_unlock(&ubi->wl_lock);
 	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
 	ubi_free_vid_buf(vidb);
 	return 0;
 }
@@ -1093,7 +1101,7 @@ static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
 		int err1;
 
 		/* Re-schedule the LEB for erasure */
-		err1 = schedule_erase(ubi, e, vol_id, lnum, 0);
+		err1 = schedule_erase(ubi, e, vol_id, lnum, 0, false);
 		if (err1) {
 			wl_entry_destroy(ubi, e);
 			err = err1;
@@ -1274,7 +1282,7 @@ retry:
 	}
 	spin_unlock(&ubi->wl_lock);
 
-	err = schedule_erase(ubi, e, vol_id, lnum, torture);
+	err = schedule_erase(ubi, e, vol_id, lnum, torture, false);
 	if (err) {
 		spin_lock(&ubi->wl_lock);
 		wl_tree_add(e, &ubi->used);
@@ -1565,7 +1573,7 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 		e->pnum = aeb->pnum;
 		e->ec = aeb->ec;
 		ubi->lookuptbl[e->pnum] = e;
-		if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {
+		if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false)) {
 			wl_entry_destroy(ubi, e);
 			goto out_free;
 		}
@@ -1644,7 +1652,7 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 			e->ec = aeb->ec;
 			ubi_assert(!ubi->lookuptbl[e->pnum]);
 			ubi->lookuptbl[e->pnum] = e;
-			if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {
+			if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false)) {
 				wl_entry_destroy(ubi, e);
 				goto out_free;
 			}