Merge tag 'upstream-4.8-rc1' of git://git.infradead.org/linux-ubifs

Pull UBI/UBIFS updates from Richard Weinberger:
 "This contains mostly cleanups and minor improvements of UBI and UBIFS"

* tag 'upstream-4.8-rc1' of git://git.infradead.org/linux-ubifs:
  ubi: Use bitmaps in Fastmap self-check code
  ubi: Be more paranoid while seaching for the most recent Fastmap
  ubi: Check whether the Fastmap anchor matches the super block
  ubi: Rework Fastmap attach base code
  ubi: Fix whitespace issue in count_fastmap_pebs()
  ubi: Introduce vol_ignored()
  ubi: Fix scan_fast() comment
  ubifs: switch_gc_head: Remove redondant sync of wbuf
  ubi: Make volume resize power cut aware
  ubi: Fix early logging
  ubi: gluebi: Fix double refcounting
  ubifs: Silence early error messages if MS_SILENT is set
  ubi: Fix race condition between ubi device creation and udev
  ubifs: Update comment for ubifs_errc
  ubi: Only read necessary size when reading the VID header
  ubifs: Make xattr structures static
  ubifs: Silence error output if MS_SILENT is set

8 files changed, 263 insertions, 75 deletions

diff --git a/drivers/mtd/ubi/attach.c b/drivers/mtd/ubi/attach.c
index c1aaf03..903becd 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),
@@ -1326,7 +1391,7 @@ static struct ubi_attach_info *alloc_ai(void)
 #ifdef CONFIG_MTD_UBI_FASTMAP
 
 /**
- * scan_fastmap - try to find a fastmap and attach from it.
+ * scan_fast - try to find a fastmap and attach from it.
  * @ubi: UBI device description object
  * @ai: attach info object
  *
@@ -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/build.c b/drivers/mtd/ubi/build.c
index ef36182..0680516 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -874,7 +874,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 	for (i = 0; i < UBI_MAX_DEVICES; i++) {
 		ubi = ubi_devices[i];
 		if (ubi && mtd->index == ubi->mtd->index) {
-			ubi_err(ubi, "mtd%d is already attached to ubi%d",
+			pr_err("ubi: mtd%d is already attached to ubi%d",
 				mtd->index, i);
 			return -EEXIST;
 		}
@@ -889,7 +889,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 	 * no sense to attach emulated MTD devices, so we prohibit this.
 	 */
 	if (mtd->type == MTD_UBIVOLUME) {
-		ubi_err(ubi, "refuse attaching mtd%d - it is already emulated on top of UBI",
+		pr_err("ubi: refuse attaching mtd%d - it is already emulated on top of UBI",
 			mtd->index);
 		return -EINVAL;
 	}
@@ -900,7 +900,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 			if (!ubi_devices[ubi_num])
 				break;
 		if (ubi_num == UBI_MAX_DEVICES) {
-			ubi_err(ubi, "only %d UBI devices may be created",
+			pr_err("ubi: only %d UBI devices may be created",
 				UBI_MAX_DEVICES);
 			return -ENFILE;
 		}
@@ -910,7 +910,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 
 		/* Make sure ubi_num is not busy */
 		if (ubi_devices[ubi_num]) {
-			ubi_err(ubi, "already exists");
+			pr_err("ubi: ubi%i already exists", ubi_num);
 			return -EEXIST;
 		}
 	}
@@ -992,6 +992,9 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 			goto out_detach;
 	}
 
+	/* Make device "available" before it becomes accessible via sysfs */
+	ubi_devices[ubi_num] = ubi;
+
 	err = uif_init(ubi, &ref);
 	if (err)
 		goto out_detach;
@@ -1036,7 +1039,6 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 	wake_up_process(ubi->bgt_thread);
 	spin_unlock(&ubi->wl_lock);
 
-	ubi_devices[ubi_num] = ubi;
 	ubi_notify_all(ubi, UBI_VOLUME_ADDED, NULL);
 	return ubi_num;
 
@@ -1047,6 +1049,7 @@ out_uif:
 	ubi_assert(ref);
 	uif_close(ubi);
 out_detach:
+	ubi_devices[ubi_num] = NULL;
 	ubi_wl_close(ubi);
 	ubi_free_internal_volumes(ubi);
 	vfree(ubi->vtbl);
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 990898b..48eb55f 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -15,20 +15,22 @@
  */
 
 #include <linux/crc32.h>
+#include <linux/bitmap.h>
 #include "ubi.h"
 
 /**
  * init_seen - allocate memory for used for debugging.
  * @ubi: UBI device description object
  */
-static inline int *init_seen(struct ubi_device *ubi)
+static inline unsigned long *init_seen(struct ubi_device *ubi)
 {
-	int *ret;
+	unsigned long *ret;
 
 	if (!ubi_dbg_chk_fastmap(ubi))
 		return NULL;
 
-	ret = kcalloc(ubi->peb_count, sizeof(int), GFP_KERNEL);
+	ret = kcalloc(BITS_TO_LONGS(ubi->peb_count), sizeof(unsigned long),
+		      GFP_KERNEL);
 	if (!ret)
 		return ERR_PTR(-ENOMEM);
 
@@ -39,7 +41,7 @@ static inline int *init_seen(struct ubi_device *ubi)
  * free_seen - free the seen logic integer array.
  * @seen: integer array of @ubi->peb_count size
  */
-static inline void free_seen(int *seen)
+static inline void free_seen(unsigned long *seen)
 {
 	kfree(seen);
 }
@@ -50,12 +52,12 @@ static inline void free_seen(int *seen)
  * @pnum: The PEB to be makred as seen
  * @seen: integer array of @ubi->peb_count size
  */
-static inline void set_seen(struct ubi_device *ubi, int pnum, int *seen)
+static inline void set_seen(struct ubi_device *ubi, int pnum, unsigned long *seen)
 {
 	if (!ubi_dbg_chk_fastmap(ubi) || !seen)
 		return;
 
-	seen[pnum] = 1;
+	set_bit(pnum, seen);
 }
 
 /**
@@ -63,7 +65,7 @@ static inline void set_seen(struct ubi_device *ubi, int pnum, int *seen)
  * @ubi: UBI device description object
  * @seen: integer array of @ubi->peb_count size
  */
-static int self_check_seen(struct ubi_device *ubi, int *seen)
+static int self_check_seen(struct ubi_device *ubi, unsigned long *seen)
 {
 	int pnum, ret = 0;
 
@@ -71,7 +73,7 @@ static int self_check_seen(struct ubi_device *ubi, int *seen)
 		return 0;
 
 	for (pnum = 0; pnum < ubi->peb_count; pnum++) {
-		if (!seen[pnum] && ubi->lookuptbl[pnum]) {
+		if (test_bit(pnum, seen) && ubi->lookuptbl[pnum]) {
 			ubi_err(ubi, "self-check failed for PEB %d, fastmap didn't see it", pnum);
 			ret = -EINVAL;
 		}
@@ -578,7 +580,7 @@ static int count_fastmap_pebs(struct ubi_attach_info *ai)
 	list_for_each_entry(aeb, &ai->free, u.list)
 		n++;
 
-	 ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
 		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
 			n++;
 
@@ -850,27 +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);
 
@@ -945,6 +977,13 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
 			goto free_hdr;
 		}
 
+		if (i == 0 && pnum != fm_anchor) {
+			ubi_err(ubi, "Fastmap anchor PEB mismatch: PEB: %i vs. %i",
+				pnum, fm_anchor);
+			ret = UBI_BAD_FASTMAP;
+			goto free_hdr;
+		}
+
 		ret = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
 		if (ret && ret != UBI_IO_BITFLIPS) {
 			ubi_err(ubi, "unable to read fastmap block# %i EC (PEB: %i)",
@@ -1102,7 +1141,7 @@ static int ubi_write_fastmap(struct ubi_device *ubi,
 	struct rb_node *tmp_rb;
 	int ret, i, j, free_peb_count, used_peb_count, vol_count;
 	int scrub_peb_count, erase_peb_count;
-	int *seen_pebs = NULL;
+	unsigned long *seen_pebs = NULL;
 
 	fm_raw = ubi->fm_buf;
 	memset(ubi->fm_buf, 0, ubi->fm_size);
diff --git a/drivers/mtd/ubi/gluebi.c b/drivers/mtd/ubi/gluebi.c
index cb7c075..1cb287e 100644
--- a/drivers/mtd/ubi/gluebi.c
+++ b/drivers/mtd/ubi/gluebi.c
@@ -99,9 +99,6 @@ static int gluebi_get_device(struct mtd_info *mtd)
 	struct gluebi_device *gluebi;
 	int ubi_mode = UBI_READONLY;
 
-	if (!try_module_get(THIS_MODULE))
-		return -ENODEV;
-
 	if (mtd->flags & MTD_WRITEABLE)
 		ubi_mode = UBI_READWRITE;
 
@@ -129,7 +126,6 @@ static int gluebi_get_device(struct mtd_info *mtd)
 				       ubi_mode);
 	if (IS_ERR(gluebi->desc)) {
 		mutex_unlock(&devices_mutex);
-		module_put(THIS_MODULE);
 		return PTR_ERR(gluebi->desc);
 	}
 	gluebi->refcnt += 1;
@@ -153,7 +149,6 @@ static void gluebi_put_device(struct mtd_info *mtd)
 	gluebi->refcnt -= 1;
 	if (gluebi->refcnt == 0)
 		ubi_close_volume(gluebi->desc);
-	module_put(THIS_MODULE);
 	mutex_unlock(&devices_mutex);
 }
 
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index 10cf3b5..ff8cafe 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -1019,7 +1019,7 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
 
 	p = (char *)vid_hdr - ubi->vid_hdr_shift;
 	read_err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
-			  ubi->vid_hdr_alsize);
+			  ubi->vid_hdr_shift + UBI_VID_HDR_SIZE);
 	if (read_err && read_err != UBI_IO_BITFLIPS && !mtd_is_eccerr(read_err))
 		return read_err;
 
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 61d4e99..b616a115 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -703,6 +703,8 @@ 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)
@@ -713,6 +715,8 @@ 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
@@ -731,6 +735,7 @@ 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;
@@ -739,6 +744,7 @@ 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;
@@ -911,7 +917,7 @@ 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
@@ -1105,4 +1111,42 @@ 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/vmt.c b/drivers/mtd/ubi/vmt.c
index 10059df..0138f52 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -488,13 +488,6 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
 		spin_unlock(&ubi->volumes_lock);
 	}
 
-	/* Change volume table record */
-	vtbl_rec = ubi->vtbl[vol_id];
-	vtbl_rec.reserved_pebs = cpu_to_be32(reserved_pebs);
-	err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
-	if (err)
-		goto out_acc;
-
 	if (pebs < 0) {
 		for (i = 0; i < -pebs; i++) {
 			err = ubi_eba_unmap_leb(ubi, vol, reserved_pebs + i);
@@ -512,6 +505,24 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
 		spin_unlock(&ubi->volumes_lock);
 	}
 
+	/*
+	 * When we shrink a volume we have to flush all pending (erase) work.
+	 * Otherwise it can happen that upon next attach UBI finds a LEB with
+	 * lnum > highest_lnum and refuses to attach.
+	 */
+	if (pebs < 0) {
+		err = ubi_wl_flush(ubi, vol_id, UBI_ALL);
+		if (err)
+			goto out_acc;
+	}
+
+	/* Change volume table record */
+	vtbl_rec = ubi->vtbl[vol_id];
+	vtbl_rec.reserved_pebs = cpu_to_be32(reserved_pebs);
+	err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
+	if (err)
+		goto out_acc;
+
 	vol->reserved_pebs = reserved_pebs;
 	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
 		vol->used_ebs = reserved_pebs;
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 959c7b12..f453326 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1598,19 +1598,44 @@ 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();
+
+		e = ubi_find_fm_block(ubi, aeb->pnum);
 
-	if (ubi->fm) {
-		ubi_assert(ubi->good_peb_count ==
-			   found_pebs + ubi->fm->used_blocks);
+		if (e) {
+			ubi_assert(!ubi->lookuptbl[e->pnum]);
+			ubi->lookuptbl[e->pnum] = e;
+		} else {
+			/*
+			 * 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;
+
+			e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+			if (!e)
+				goto out_free;
 
-		for (i = 0; i < ubi->fm->used_blocks; i++) {
-			e = ubi->fm->e[i];
+			e->pnum = aeb->pnum;
+			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)) {
+				wl_entry_destroy(ubi, e);
+				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);