[PATCH 2/2] ubi: fastmap: wl: Schedule fm_work if wear-leveling pool is empty

[Zhihao Cheng]

Since commit 14072ee33d5a ("ubi: fastmap: Check wl_pool for free peb
before wear leveling"), wear_leveling_worker() won't schedule fm_work
if wear-leveling pool is empty, which could temporarily disable the
wear-leveling until the fastmap is updated(eg. pool becomes empty).
Fix it by scheduling fm_work if wl_pool is empty during wear-leveing.

Fixes: 14072ee33d5a ("ubi: fastmap: Check wl_pool for free peb before wear leveling")
Signed-off-by: Zhihao Cheng <chengzhihao1 at huawei.com>
---
 drivers/mtd/ubi/fastmap-wl.c | 19 ++++++++++++++++---
 drivers/mtd/ubi/wl.c         |  2 +-
 drivers/mtd/ubi/wl.h         |  3 ++-
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c
index 2a9cc9413c42..9bdb6525f128 100644
--- a/drivers/mtd/ubi/fastmap-wl.c
+++ b/drivers/mtd/ubi/fastmap-wl.c
@@ -346,14 +346,27 @@ int ubi_wl_get_peb(struct ubi_device *ubi)
  * WL sub-system.
  *
  * @ubi: UBI device description object
+ * @need_fill: whether to fill wear-leveling pool when no PEBs are found
  */
-static struct ubi_wl_entry *next_peb_for_wl(struct ubi_device *ubi)
+static struct ubi_wl_entry *next_peb_for_wl(struct ubi_device *ubi,
+					    bool need_fill)
 {
 	struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
 	int pnum;
 
-	if (pool->used == pool->size)
+	if (pool->used == pool->size) {
+		if (need_fill && !ubi->fm_work_scheduled) {
+			/*
+			 * We cannot update the fastmap here because this
+			 * function is called in atomic context.
+			 * Let's fail here and refill/update it as soon as
+			 * possible.
+			 */
+			ubi->fm_work_scheduled = 1;
+			schedule_work(&ubi->fm_work);
+		}
 		return NULL;
+	}
 
 	pnum = pool->pebs[pool->used];
 	return ubi->lookuptbl[pnum];
@@ -375,7 +388,7 @@ static bool need_wear_leveling(struct ubi_device *ubi)
 	if (!ubi->used.rb_node)
 		return false;
 
-	e = next_peb_for_wl(ubi);
+	e = next_peb_for_wl(ubi, false);
 	if (!e) {
 		if (!ubi->free.rb_node)
 			return false;
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 8a26968aba11..fbd399cf6503 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -683,7 +683,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 	ubi_assert(!ubi->move_to_put);
 
 #ifdef CONFIG_MTD_UBI_FASTMAP
-	if (!next_peb_for_wl(ubi) ||
+	if (!next_peb_for_wl(ubi, true) ||
 #else
 	if (!ubi->free.rb_node ||
 #endif
diff --git a/drivers/mtd/ubi/wl.h b/drivers/mtd/ubi/wl.h
index 7b6715ef6d4a..a69169c35e31 100644
--- a/drivers/mtd/ubi/wl.h
+++ b/drivers/mtd/ubi/wl.h
@@ -5,7 +5,8 @@
 static void update_fastmap_work_fn(struct work_struct *wrk);
 static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root);
 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi);
-static struct ubi_wl_entry *next_peb_for_wl(struct ubi_device *ubi);
+static struct ubi_wl_entry *next_peb_for_wl(struct ubi_device *ubi,
+					    bool need_fill);
 static bool need_wear_leveling(struct ubi_device *ubi);
 static void ubi_fastmap_close(struct ubi_device *ubi);
 static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count)
-- 
2.39.2