Merge branch 'linux-linaro-lsk-v4.4' of git://git.linaro.org/kernel/linux-linaro-stable.git

* linux-linaro-lsk-v4.4: (519 commits)
  Linux 4.4.154
  cdrom: Fix info leak/OOB read in cdrom_ioctl_drive_status
  iscsi target: fix session creation failure handling
  scsi: core: Avoid that SCSI device removal through sysfs triggers a deadlock
  scsi: sysfs: Introduce sysfs_{un,}break_active_protection()
  MIPS: lib: Provide MIPS64r6 __multi3() for GCC < 7
  MIPS: Correct the 64-bit DSP accumulator register size
  kprobes: Make list and blacklist root user read only
  s390/pci: fix out of bounds access during irq setup
  s390/qdio: reset old sbal_state flags
  s390: fix br_r1_trampoline for machines without exrl
  x86/spectre: Add missing family 6 check to microcode check
  x86/irqflags: Mark native_restore_fl extern inline
  pinctrl: freescale: off by one in imx1_pinconf_group_dbg_show()
  ASoC: sirf: Fix potential NULL pointer dereference
  ASoC: dpcm: don't merge format from invalid codec dai
  udl-kms: fix crash due to uninitialized memory
  udl-kms: handle allocation failure
  udl-kms: change down_interruptible to down
  fuse: Add missed unlock_page() to fuse_readpages_fill()
  ...

Conflicts:
	Makefile
	arch/arm64/mm/init.c
	fs/squashfs/block.c
	include/uapi/linux/prctl.h
	kernel/sys.c

Change-Id: Ie03b5adfbbb4ab2bf16bc55d99f0d8a9c540a53b

7 files changed, 302 insertions, 75 deletions

diff --git a/drivers/mtd/nand/fsl_ifc_nand.c b/drivers/mtd/nand/fsl_ifc_nand.c
index 5e3fa5861039..2c0bbaed3609 100644
--- a/drivers/mtd/nand/fsl_ifc_nand.c
+++ b/drivers/mtd/nand/fsl_ifc_nand.c
@@ -449,9 +449,16 @@ static void fsl_ifc_cmdfunc(struct mtd_info *mtd, unsigned int command,
 
 	case NAND_CMD_READID:
 	case NAND_CMD_PARAM: {
+		/*
+		 * For READID, read 8 bytes that are currently used.
+		 * For PARAM, read all 3 copies of 256-bytes pages.
+		 */
+		int len = 8;
 		int timing = IFC_FIR_OP_RB;
-		if (command == NAND_CMD_PARAM)
+		if (command == NAND_CMD_PARAM) {
 			timing = IFC_FIR_OP_RBCD;
+			len = 256 * 3;
+		}
 
 		ifc_out32((IFC_FIR_OP_CW0 << IFC_NAND_FIR0_OP0_SHIFT) |
 			  (IFC_FIR_OP_UA  << IFC_NAND_FIR0_OP1_SHIFT) |
@@ -461,12 +468,8 @@ static void fsl_ifc_cmdfunc(struct mtd_info *mtd, unsigned int command,
 			  &ifc->ifc_nand.nand_fcr0);
 		ifc_out32(column, &ifc->ifc_nand.row3);
 
-		/*
-		 * although currently it's 8 bytes for READID, we always read
-		 * the maximum 256 bytes(for PARAM)
-		 */
-		ifc_out32(256, &ifc->ifc_nand.nand_fbcr);
-		ifc_nand_ctrl->read_bytes = 256;
+		ifc_out32(len, &ifc->ifc_nand.nand_fbcr);
+		ifc_nand_ctrl->read_bytes = len;
 
 		set_addr(mtd, 0, 0, 0);
 		fsl_ifc_run_command(mtd);
diff --git a/drivers/mtd/ubi/attach.c b/drivers/mtd/ubi/attach.c
index c1aaf0336cf2..5cde3ad1665e 100644
--- a/drivers/mtd/ubi/attach.c
+++ b/drivers/mtd/ubi/attach.c
@@ -175,6 +175,40 @@ static int add_corrupted(struct ubi_attach_info *ai, int pnum, int ec)
 }
 
 /**
+ * add_fastmap - add a Fastmap related physical eraseblock.
+ * @ai: attaching information
+ * @pnum: physical eraseblock number the VID header came from
+ * @vid_hdr: the volume identifier header
+ * @ec: erase counter of the physical eraseblock
+ *
+ * This function allocates a 'struct ubi_ainf_peb' object for a Fastamp
+ * physical eraseblock @pnum and adds it to the 'fastmap' list.
+ * Such blocks can be Fastmap super and data blocks from both the most
+ * recent Fastmap we're attaching from or from old Fastmaps which will
+ * be erased.
+ */
+static int add_fastmap(struct ubi_attach_info *ai, int pnum,
+		       struct ubi_vid_hdr *vid_hdr, int ec)
+{
+	struct ubi_ainf_peb *aeb;
+
+	aeb = kmem_cache_alloc(ai->aeb_slab_cache, GFP_KERNEL);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->pnum = pnum;
+	aeb->vol_id = be32_to_cpu(vidh->vol_id);
+	aeb->sqnum = be64_to_cpu(vidh->sqnum);
+	aeb->ec = ec;
+	list_add(&aeb->u.list, &ai->fastmap);
+
+	dbg_bld("add to fastmap list: PEB %d, vol_id %d, sqnum: %llu", pnum,
+		aeb->vol_id, aeb->sqnum);
+
+	return 0;
+}
+
+/**
  * validate_vid_hdr - check volume identifier header.
  * @ubi: UBI device description object
  * @vid_hdr: the volume identifier header to check
@@ -803,13 +837,26 @@ out_unlock:
 	return err;
 }
 
+static bool vol_ignored(int vol_id)
+{
+	switch (vol_id) {
+		case UBI_LAYOUT_VOLUME_ID:
+		return true;
+	}
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	return ubi_is_fm_vol(vol_id);
+#else
+	return false;
+#endif
+}
+
 /**
  * scan_peb - scan and process UBI headers of a PEB.
  * @ubi: UBI device description object
  * @ai: attaching information
  * @pnum: the physical eraseblock number
- * @vid: The volume ID of the found volume will be stored in this pointer
- * @sqnum: The sqnum of the found volume will be stored in this pointer
+ * @fast: true if we're scanning for a Fastmap
  *
  * This function reads UBI headers of PEB @pnum, checks them, and adds
  * information about this PEB to the corresponding list or RB-tree in the
@@ -817,9 +864,9 @@ out_unlock:
  * successfully handled and a negative error code in case of failure.
  */
 static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
-		    int pnum, int *vid, unsigned long long *sqnum)
+		    int pnum, bool fast)
 {
-	long long uninitialized_var(ec);
+	long long ec;
 	int err, bitflips = 0, vol_id = -1, ec_err = 0;
 
 	dbg_bld("scan PEB %d", pnum);
@@ -935,6 +982,20 @@ static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
 			 */
 			ai->maybe_bad_peb_count += 1;
 	case UBI_IO_BAD_HDR:
+			/*
+			 * If we're facing a bad VID header we have to drop *all*
+			 * Fastmap data structures we find. The most recent Fastmap
+			 * could be bad and therefore there is a chance that we attach
+			 * from an old one. On a fine MTD stack a PEB must not render
+			 * bad all of a sudden, but the reality is different.
+			 * So, let's be paranoid and help finding the root cause by
+			 * falling back to scanning mode instead of attaching with a
+			 * bad EBA table and cause data corruption which is hard to
+			 * analyze.
+			 */
+			if (fast)
+				ai->force_full_scan = 1;
+
 		if (ec_err)
 			/*
 			 * Both headers are corrupted. There is a possibility
@@ -991,21 +1052,15 @@ static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
 	}
 
 	vol_id = be32_to_cpu(vidh->vol_id);
-	if (vid)
-		*vid = vol_id;
-	if (sqnum)
-		*sqnum = be64_to_cpu(vidh->sqnum);
-	if (vol_id > UBI_MAX_VOLUMES && vol_id != UBI_LAYOUT_VOLUME_ID) {
+	if (vol_id > UBI_MAX_VOLUMES && !vol_ignored(vol_id)) {
 		int lnum = be32_to_cpu(vidh->lnum);
 
 		/* Unsupported internal volume */
 		switch (vidh->compat) {
 		case UBI_COMPAT_DELETE:
-			if (vol_id != UBI_FM_SB_VOLUME_ID
-			    && vol_id != UBI_FM_DATA_VOLUME_ID) {
-				ubi_msg(ubi, "\"delete\" compatible internal volume %d:%d found, will remove it",
-					vol_id, lnum);
-			}
+			ubi_msg(ubi, "\"delete\" compatible internal volume %d:%d found, will remove it",
+				vol_id, lnum);
+
 			err = add_to_list(ai, pnum, vol_id, lnum,
 					  ec, 1, &ai->erase);
 			if (err)
@@ -1037,7 +1092,12 @@ static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
 	if (ec_err)
 		ubi_warn(ubi, "valid VID header but corrupted EC header at PEB %d",
 			 pnum);
-	err = ubi_add_to_av(ubi, ai, pnum, ec, vidh, bitflips);
+
+	if (ubi_is_fm_vol(vol_id))
+		err = add_fastmap(ai, pnum, vidh, ec);
+	else
+		err = ubi_add_to_av(ubi, ai, pnum, ec, vidh, bitflips);
+
 	if (err)
 		return err;
 
@@ -1186,6 +1246,10 @@ static void destroy_ai(struct ubi_attach_info *ai)
 		list_del(&aeb->u.list);
 		kmem_cache_free(ai->aeb_slab_cache, aeb);
 	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->fastmap, u.list) {
+		list_del(&aeb->u.list);
+		kmem_cache_free(ai->aeb_slab_cache, aeb);
+	}
 
 	/* Destroy the volume RB-tree */
 	rb = ai->volumes.rb_node;
@@ -1245,7 +1309,7 @@ static int scan_all(struct ubi_device *ubi, struct ubi_attach_info *ai,
 		cond_resched();
 
 		dbg_gen("process PEB %d", pnum);
-		err = scan_peb(ubi, ai, pnum, NULL, NULL);
+		err = scan_peb(ubi, ai, pnum, false);
 		if (err < 0)
 			goto out_vidh;
 	}
@@ -1311,6 +1375,7 @@ static struct ubi_attach_info *alloc_ai(void)
 	INIT_LIST_HEAD(&ai->free);
 	INIT_LIST_HEAD(&ai->erase);
 	INIT_LIST_HEAD(&ai->alien);
+	INIT_LIST_HEAD(&ai->fastmap);
 	ai->volumes = RB_ROOT;
 	ai->aeb_slab_cache = kmem_cache_create("ubi_aeb_slab_cache",
 					       sizeof(struct ubi_ainf_peb),
@@ -1337,52 +1402,58 @@ static struct ubi_attach_info *alloc_ai(void)
  */
 static int scan_fast(struct ubi_device *ubi, struct ubi_attach_info **ai)
 {
-	int err, pnum, fm_anchor = -1;
-	unsigned long long max_sqnum = 0;
+	int err, pnum;
+	struct ubi_attach_info *scan_ai;
 
 	err = -ENOMEM;
 
+	scan_ai = alloc_ai();
+	if (!scan_ai)
+		goto out;
+
 	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
 	if (!ech)
-		goto out;
+		goto out_ai;
 
 	vidh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
 	if (!vidh)
 		goto out_ech;
 
 	for (pnum = 0; pnum < UBI_FM_MAX_START; pnum++) {
-		int vol_id = -1;
-		unsigned long long sqnum = -1;
 		cond_resched();
 
 		dbg_gen("process PEB %d", pnum);
-		err = scan_peb(ubi, *ai, pnum, &vol_id, &sqnum);
+		err = scan_peb(ubi, scan_ai, pnum, true);
 		if (err < 0)
 			goto out_vidh;
-
-		if (vol_id == UBI_FM_SB_VOLUME_ID && sqnum > max_sqnum) {
-			max_sqnum = sqnum;
-			fm_anchor = pnum;
-		}
 	}
 
 	ubi_free_vid_hdr(ubi, vidh);
 	kfree(ech);
 
-	if (fm_anchor < 0)
-		return UBI_NO_FASTMAP;
+	if (scan_ai->force_full_scan)
+		err = UBI_NO_FASTMAP;
+	else
+		err = ubi_scan_fastmap(ubi, *ai, scan_ai);
 
-	destroy_ai(*ai);
-	*ai = alloc_ai();
-	if (!*ai)
-		return -ENOMEM;
+	if (err) {
+		/*
+		 * Didn't attach via fastmap, do a full scan but reuse what
+		 * we've aready scanned.
+		 */
+		destroy_ai(*ai);
+		*ai = scan_ai;
+	} else
+		destroy_ai(scan_ai);
 
-	return ubi_scan_fastmap(ubi, *ai, fm_anchor);
+	return err;
 
 out_vidh:
 	ubi_free_vid_hdr(ubi, vidh);
 out_ech:
 	kfree(ech);
+out_ai:
+	destroy_ai(scan_ai);
 out:
 	return err;
 }
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index c4a25c858c07..03cf0553ec1b 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -1178,6 +1178,8 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 	struct ubi_volume *vol;
 	uint32_t crc;
 
+	ubi_assert(rwsem_is_locked(&ubi->fm_eba_sem));
+
 	vol_id = be32_to_cpu(vid_hdr->vol_id);
 	lnum = be32_to_cpu(vid_hdr->lnum);
 
@@ -1346,9 +1348,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 	}
 
 	ubi_assert(vol->eba_tbl[lnum] == from);
-	down_read(&ubi->fm_eba_sem);
 	vol->eba_tbl[lnum] = to;
-	up_read(&ubi->fm_eba_sem);
 
 out_unlock_buf:
 	mutex_unlock(&ubi->buf_mutex);
diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c
index ed62f1efe6eb..69dd21679a30 100644
--- a/drivers/mtd/ubi/fastmap-wl.c
+++ b/drivers/mtd/ubi/fastmap-wl.c
@@ -262,6 +262,8 @@ static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
 	struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
 	int pnum;
 
+	ubi_assert(rwsem_is_locked(&ubi->fm_eba_sem));
+
 	if (pool->used == pool->size) {
 		/* We cannot update the fastmap here because this
 		 * function is called in atomic context.
@@ -303,7 +305,7 @@ int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
 
 	wrk->anchor = 1;
 	wrk->func = &wear_leveling_worker;
-	schedule_ubi_work(ubi, wrk);
+	__schedule_ubi_work(ubi, wrk);
 	return 0;
 }
 
@@ -344,7 +346,7 @@ int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
 	spin_unlock(&ubi->wl_lock);
 
 	vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
-	return schedule_erase(ubi, e, vol_id, lnum, torture);
+	return schedule_erase(ubi, e, vol_id, lnum, torture, true);
 }
 
 /**
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index bba7dd1b5ebf..72e89b352034 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -326,6 +326,7 @@ static int update_vol(struct ubi_device *ubi, struct ubi_attach_info *ai,
 			aeb->pnum = new_aeb->pnum;
 			aeb->copy_flag = new_vh->copy_flag;
 			aeb->scrub = new_aeb->scrub;
+			aeb->sqnum = new_aeb->sqnum;
 			kmem_cache_free(ai->aeb_slab_cache, new_aeb);
 
 		/* new_aeb is older */
@@ -851,27 +852,57 @@ fail:
 }
 
 /**
+ * find_fm_anchor - find the most recent Fastmap superblock (anchor)
+ * @ai: UBI attach info to be filled
+ */
+static int find_fm_anchor(struct ubi_attach_info *ai)
+{
+	int ret = -1;
+	struct ubi_ainf_peb *aeb;
+	unsigned long long max_sqnum = 0;
+
+	list_for_each_entry(aeb, &ai->fastmap, u.list) {
+		if (aeb->vol_id == UBI_FM_SB_VOLUME_ID && aeb->sqnum > max_sqnum) {
+			max_sqnum = aeb->sqnum;
+			ret = aeb->pnum;
+		}
+	}
+
+	return ret;
+}
+
+/**
  * ubi_scan_fastmap - scan the fastmap.
  * @ubi: UBI device object
  * @ai: UBI attach info to be filled
- * @fm_anchor: The fastmap starts at this PEB
+ * @scan_ai: UBI attach info from the first 64 PEBs,
+ *           used to find the most recent Fastmap data structure
  *
  * Returns 0 on success, UBI_NO_FASTMAP if no fastmap was found,
  * UBI_BAD_FASTMAP if one was found but is not usable.
  * < 0 indicates an internal error.
  */
 int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
-		     int fm_anchor)
+		     struct ubi_attach_info *scan_ai)
 {
 	struct ubi_fm_sb *fmsb, *fmsb2;
 	struct ubi_vid_hdr *vh;
 	struct ubi_ec_hdr *ech;
 	struct ubi_fastmap_layout *fm;
-	int i, used_blocks, pnum, ret = 0;
+	struct ubi_ainf_peb *tmp_aeb, *aeb;
+	int i, used_blocks, pnum, fm_anchor, ret = 0;
 	size_t fm_size;
 	__be32 crc, tmp_crc;
 	unsigned long long sqnum = 0;
 
+	fm_anchor = find_fm_anchor(scan_ai);
+	if (fm_anchor < 0)
+		return UBI_NO_FASTMAP;
+
+	/* Move all (possible) fastmap blocks into our new attach structure. */
+	list_for_each_entry_safe(aeb, tmp_aeb, &scan_ai->fastmap, u.list)
+		list_move_tail(&aeb->u.list, &ai->fastmap);
+
 	down_write(&ubi->fm_protect);
 	memset(ubi->fm_buf, 0, ubi->fm_size);
 
@@ -1484,22 +1515,30 @@ int ubi_update_fastmap(struct ubi_device *ubi)
 	struct ubi_wl_entry *tmp_e;
 
 	down_write(&ubi->fm_protect);
+	down_write(&ubi->work_sem);
+	down_write(&ubi->fm_eba_sem);
 
 	ubi_refill_pools(ubi);
 
 	if (ubi->ro_mode || ubi->fm_disabled) {
+		up_write(&ubi->fm_eba_sem);
+		up_write(&ubi->work_sem);
 		up_write(&ubi->fm_protect);
 		return 0;
 	}
 
 	ret = ubi_ensure_anchor_pebs(ubi);
 	if (ret) {
+		up_write(&ubi->fm_eba_sem);
+		up_write(&ubi->work_sem);
 		up_write(&ubi->fm_protect);
 		return ret;
 	}
 
 	new_fm = kzalloc(sizeof(*new_fm), GFP_KERNEL);
 	if (!new_fm) {
+		up_write(&ubi->fm_eba_sem);
+		up_write(&ubi->work_sem);
 		up_write(&ubi->fm_protect);
 		return -ENOMEM;
 	}
@@ -1608,16 +1647,14 @@ int ubi_update_fastmap(struct ubi_device *ubi)
 		new_fm->e[0] = tmp_e;
 	}
 
-	down_write(&ubi->work_sem);
-	down_write(&ubi->fm_eba_sem);
 	ret = ubi_write_fastmap(ubi, new_fm);
-	up_write(&ubi->fm_eba_sem);
-	up_write(&ubi->work_sem);
 
 	if (ret)
 		goto err;
 
 out_unlock:
+	up_write(&ubi->fm_eba_sem);
+	up_write(&ubi->work_sem);
 	up_write(&ubi->fm_protect);
 	kfree(old_fm);
 	return ret;
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index de1ea2e4c37d..05d9ec66437c 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -699,6 +699,8 @@ struct ubi_ainf_volume {
  * @erase: list of physical eraseblocks which have to be erased
  * @alien: list of physical eraseblocks which should not be used by UBI (e.g.,
  *         those belonging to "preserve"-compatible internal volumes)
+ * @fastmap: list of physical eraseblocks which relate to fastmap (e.g.,
+ *           eraseblocks of the current and not yet erased old fastmap blocks)
  * @corr_peb_count: count of PEBs in the @corr list
  * @empty_peb_count: count of PEBs which are presumably empty (contain only
  *                   0xFF bytes)
@@ -709,6 +711,8 @@ struct ubi_ainf_volume {
  * @vols_found: number of volumes found
  * @highest_vol_id: highest volume ID
  * @is_empty: flag indicating whether the MTD device is empty or not
+ * @force_full_scan: flag indicating whether we need to do a full scan and drop
+		     all existing Fastmap data structures
  * @min_ec: lowest erase counter value
  * @max_ec: highest erase counter value
  * @max_sqnum: highest sequence number value
@@ -727,6 +731,7 @@ struct ubi_attach_info {
 	struct list_head free;
 	struct list_head erase;
 	struct list_head alien;
+	struct list_head fastmap;
 	int corr_peb_count;
 	int empty_peb_count;
 	int alien_peb_count;
@@ -735,6 +740,7 @@ struct ubi_attach_info {
 	int vols_found;
 	int highest_vol_id;
 	int is_empty;
+	int force_full_scan;
 	int min_ec;
 	int max_ec;
 	unsigned long long max_sqnum;
@@ -907,7 +913,7 @@ int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
 size_t ubi_calc_fm_size(struct ubi_device *ubi);
 int ubi_update_fastmap(struct ubi_device *ubi);
 int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
-		     int fm_anchor);
+		     struct ubi_attach_info *scan_ai);
 #else
 static inline int ubi_update_fastmap(struct ubi_device *ubi) { return 0; }
 #endif
@@ -1101,4 +1107,42 @@ static inline int idx2vol_id(const struct ubi_device *ubi, int idx)
 		return idx;
 }
 
+/**
+ * ubi_is_fm_vol - check whether a volume ID is a Fastmap volume.
+ * @vol_id: volume ID
+ */
+static inline bool ubi_is_fm_vol(int vol_id)
+{
+	switch (vol_id) {
+		case UBI_FM_SB_VOLUME_ID:
+		case UBI_FM_DATA_VOLUME_ID:
+		return true;
+	}
+
+	return false;
+}
+
+/**
+ * ubi_find_fm_block - check whether a PEB is part of the current Fastmap.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock to look for
+ *
+ * This function returns a wear leveling object if @pnum relates to the current
+ * fastmap, @NULL otherwise.
+ */
+static inline struct ubi_wl_entry *ubi_find_fm_block(const struct ubi_device *ubi,
+						     int pnum)
+{
+	int i;
+
+	if (ubi->fm) {
+		for (i = 0; i < ubi->fm->used_blocks; i++) {
+			if (ubi->fm->e[i]->pnum == pnum)
+				return ubi->fm->e[i];
+		}
+	}
+
+	return NULL;
+}
+
 #endif /* !__UBI_UBI_H__ */
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index ca9746f41ff1..b3c1b8106a68 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;
 }
 
@@ -658,6 +661,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 	if (!vid_hdr)
 		return -ENOMEM;
 
+	down_read(&ubi->fm_eba_sem);
 	mutex_lock(&ubi->move_mutex);
 	spin_lock(&ubi->wl_lock);
 	ubi_assert(!ubi->move_from && !ubi->move_to);
@@ -884,6 +888,7 @@ 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;
 
 	/*
@@ -925,6 +930,7 @@ out_not_moved:
 	}
 
 	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
 	return 0;
 
 out_error:
@@ -946,6 +952,7 @@ 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;
 
@@ -953,6 +960,7 @@ 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_hdr(ubi, vid_hdr);
 	return 0;
 }
@@ -1075,7 +1083,7 @@ 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;
@@ -1256,7 +1264,7 @@ 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);
@@ -1501,6 +1509,46 @@ static void shutdown_work(struct ubi_device *ubi)
 }
 
 /**
+ * erase_aeb - erase a PEB given in UBI attach info PEB
+ * @ubi: UBI device description object
+ * @aeb: UBI attach info PEB
+ * @sync: If true, erase synchronously. Otherwise schedule for erasure
+ */
+static int erase_aeb(struct ubi_device *ubi, struct ubi_ainf_peb *aeb, bool sync)
+{
+	struct ubi_wl_entry *e;
+	int err;
+
+	e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+	if (!e)
+		return -ENOMEM;
+
+	e->pnum = aeb->pnum;
+	e->ec = aeb->ec;
+	ubi->lookuptbl[e->pnum] = e;
+
+	if (sync) {
+		err = sync_erase(ubi, e, false);
+		if (err)
+			goto out_free;
+
+		wl_tree_add(e, &ubi->free);
+		ubi->free_count++;
+	} else {
+		err = schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false);
+		if (err)
+			goto out_free;
+	}
+
+	return 0;
+
+out_free:
+	wl_entry_destroy(ubi, e);
+
+	return err;
+}
+
+/**
  * ubi_wl_init - initialize the WL sub-system using attaching information.
  * @ubi: UBI device description object
  * @ai: attaching information
@@ -1537,17 +1585,9 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 	list_for_each_entry_safe(aeb, tmp, &ai->erase, u.list) {
 		cond_resched();
 
-		e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
-		if (!e)
-			goto out_free;
-
-		e->pnum = aeb->pnum;
-		e->ec = aeb->ec;
-		ubi->lookuptbl[e->pnum] = e;
-		if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {
-			wl_entry_destroy(ubi, e);
+		err = erase_aeb(ubi, aeb, false);
+		if (err)
 			goto out_free;
-		}
 
 		found_pebs++;
 	}
@@ -1598,19 +1638,49 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 		}
 	}
 
-	dbg_wl("found %i PEBs", found_pebs);
+	list_for_each_entry(aeb, &ai->fastmap, u.list) {
+		cond_resched();
 
-	if (ubi->fm) {
-		ubi_assert(ubi->good_peb_count ==
-			   found_pebs + ubi->fm->used_blocks);
+		e = ubi_find_fm_block(ubi, aeb->pnum);
 
-		for (i = 0; i < ubi->fm->used_blocks; i++) {
-			e = ubi->fm->e[i];
+		if (e) {
+			ubi_assert(!ubi->lookuptbl[e->pnum]);
 			ubi->lookuptbl[e->pnum] = e;
+		} else {
+			bool sync = false;
+
+			/*
+			 * Usually old Fastmap PEBs are scheduled for erasure
+			 * and we don't have to care about them but if we face
+			 * an power cut before scheduling them we need to
+			 * take care of them here.
+			 */
+			if (ubi->lookuptbl[aeb->pnum])
+				continue;
+
+			/*
+			 * The fastmap update code might not find a free PEB for
+			 * writing the fastmap anchor to and then reuses the
+			 * current fastmap anchor PEB. When this PEB gets erased
+			 * and a power cut happens before it is written again we
+			 * must make sure that the fastmap attach code doesn't
+			 * find any outdated fastmap anchors, hence we erase the
+			 * outdated fastmap anchor PEBs synchronously here.
+			 */
+			if (aeb->vol_id == UBI_FM_SB_VOLUME_ID)
+				sync = true;
+
+			err = erase_aeb(ubi, aeb, sync);
+			if (err)
+				goto out_free;
 		}
+
+		found_pebs++;
 	}
-	else
-		ubi_assert(ubi->good_peb_count == found_pebs);
+
+	dbg_wl("found %i PEBs", found_pebs);
+
+	ubi_assert(ubi->good_peb_count == found_pebs);
 
 	reserved_pebs = WL_RESERVED_PEBS;
 	ubi_fastmap_init(ubi, &reserved_pebs);