Merge tag 'for-linus-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs

Pull UBI update from Richard Weinberger:
 "This contains a single change for UBI:

   - Select fastmap anchor PEBs considering wear level rules"

* tag 'for-linus-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs:
  ubi: Select fastmap anchor PEBs considering wear level rules

drivers/mtd/ubi/fastmap-wl.c

@@ -116,6 +116,21 @@ void ubi_refill_pools(struct ubi_device *ubi)
 	wl_pool->size = 0;
 	pool->size = 0;
 
+	if (ubi->fm_anchor) {
+		wl_tree_add(ubi->fm_anchor, &ubi->free);
+		ubi->free_count++;
+	}
+	if (ubi->fm_next_anchor) {
+		wl_tree_add(ubi->fm_next_anchor, &ubi->free);
+		ubi->free_count++;
+	}
+
+	/* All available PEBs are in ubi->free, now is the time to get
+	 * the best anchor PEBs.
+	 */
+	ubi->fm_anchor = ubi_wl_get_fm_peb(ubi, 1);
+	ubi->fm_next_anchor = ubi_wl_get_fm_peb(ubi, 1);
+
 	for (;;) {
 		enough = 0;
 		if (pool->size < pool->max_size) {
@@ -271,26 +286,20 @@ static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
 int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
 {
 	struct ubi_work *wrk;
-	struct ubi_wl_entry *anchor;
 
 	spin_lock(&ubi->wl_lock);
 
-	/* Do we already have an anchor? */
-	if (ubi->fm_anchor) {
-		spin_unlock(&ubi->wl_lock);
-		return 0;
-	}
-
-	/* See if we can find an anchor PEB on the list of free PEBs */
-	anchor = ubi_wl_get_fm_peb(ubi, 1);
-	if (anchor) {
-		ubi->fm_anchor = anchor;
-		spin_unlock(&ubi->wl_lock);
-		return 0;
+	/* Do we have a next anchor? */
+	if (!ubi->fm_next_anchor) {
+		ubi->fm_next_anchor = ubi_wl_get_fm_peb(ubi, 1);
+		if (!ubi->fm_next_anchor)
+			/* Tell wear leveling to produce a new anchor PEB */
+			ubi->fm_do_produce_anchor = 1;
 	}
 
-	/* No luck, trigger wear leveling to produce a new anchor PEB */
-	ubi->fm_do_produce_anchor = 1;
+	/* Do wear leveling to get a new anchor PEB or check the
+	 * existing next anchor candidate.
+	 */
 	if (ubi->wl_scheduled) {
 		spin_unlock(&ubi->wl_lock);
 		return 0;

drivers/mtd/ubi/fastmap.c

@@ -1220,6 +1220,17 @@ static int ubi_write_fastmap(struct ubi_device *ubi,
 		fm_pos += sizeof(*fec);
 		ubi_assert(fm_pos <= ubi->fm_size);
 	}
+	if (ubi->fm_next_anchor) {
+		fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+		fec->pnum = cpu_to_be32(ubi->fm_next_anchor->pnum);
+		set_seen(ubi, ubi->fm_next_anchor->pnum, seen_pebs);
+		fec->ec = cpu_to_be32(ubi->fm_next_anchor->ec);
+
+		free_peb_count++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= ubi->fm_size);
+	}
 	fmh->free_peb_count = cpu_to_be32(free_peb_count);
 
 	ubi_for_each_used_peb(ubi, wl_e, tmp_rb) {

drivers/mtd/ubi/ubi.h

@@ -491,7 +491,8 @@ struct ubi_debug_info {
  * @fm_work: fastmap work queue
  * @fm_work_scheduled: non-zero if fastmap work was scheduled
  * @fast_attach: non-zero if UBI was attached by fastmap
- * @fm_anchor: The next anchor PEB to use for fastmap
+ * @fm_anchor: The new anchor PEB used during fastmap update
+ * @fm_next_anchor: An anchor PEB candidate for the next time fastmap is updated
  * @fm_do_produce_anchor: If true produce an anchor PEB in wl
  *
  * @used: RB-tree of used physical eraseblocks
@@ -602,6 +603,7 @@ struct ubi_device {
 	int fm_work_scheduled;
 	int fast_attach;
 	struct ubi_wl_entry *fm_anchor;
+	struct ubi_wl_entry *fm_next_anchor;
 	int fm_do_produce_anchor;
 
 	/* Wear-leveling sub-system's stuff */

drivers/mtd/ubi/wl.c

@@ -687,20 +687,27 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 	}
 
 #ifdef CONFIG_MTD_UBI_FASTMAP
-	if (ubi->fm_do_produce_anchor) {
 	e1 = find_anchor_wl_entry(&ubi->used);
+	if (e1 && ubi->fm_next_anchor &&
+	    (ubi->fm_next_anchor->ec - e1->ec >= UBI_WL_THRESHOLD)) {
+		ubi->fm_do_produce_anchor = 1;
+		/* fm_next_anchor is no longer considered a good anchor
+		 * candidate.
+		 * NULL assignment also prevents multiple wear level checks
+		 * of this PEB.
+		 */
+		wl_tree_add(ubi->fm_next_anchor, &ubi->free);
+		ubi->fm_next_anchor = NULL;
+		ubi->free_count++;
+	}
+
+	if (ubi->fm_do_produce_anchor) {
 		if (!e1)
 			goto out_cancel;
 		e2 = get_peb_for_wl(ubi);
 		if (!e2)
 			goto out_cancel;
 
-		/*
-		 * Anchor move within the anchor area is useless.
-		 */
-		if (e2->pnum < UBI_FM_MAX_START)
-			goto out_cancel;
-
 		self_check_in_wl_tree(ubi, e1, &ubi->used);
 		rb_erase(&e1->u.rb, &ubi->used);
 		dbg_wl("anchor-move PEB %d to PEB %d", e1->pnum, e2->pnum);
@@ -1079,8 +1086,11 @@ static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
 	if (!err) {
 		spin_lock(&ubi->wl_lock);
 
-		if (!ubi->fm_anchor && e->pnum < UBI_FM_MAX_START) {
-			ubi->fm_anchor = e;
+		if (!ubi->fm_next_anchor && e->pnum < UBI_FM_MAX_START) {
+			/* Abort anchor production, if needed it will be
+			 * enabled again in the wear leveling started below.
+			 */
+			ubi->fm_next_anchor = e;
 			ubi->fm_do_produce_anchor = 0;
 		} else {
 			wl_tree_add(e, &ubi->free);